[PATCH 0/10] Add yaffs2 file system: Fourth patchset

[PATCH 0/10] Add yaffs2 file system: Fourth patchset

[Charles Manning]

This is the fourth submission of a yaffs2 patchset.

I would like to thank everyone that has given comments so far. They
have been most helpful.

I would like to thank CELF (now part of Linux Foundation) and Google
for sponsoring the effort to get yaffs2 mainlined.

This code is patched from 371b2eaad7d9c4947ec1e5c5f0576b7e118df617
at git://www.aleph1.co.uk/yaffs2.

This patch set takes onboard almost all the comments provided since the
last set of patches. Most noteably :
* Removal of almost all the wrapper macros. Pretty much all that remains
is some wrapping (YCHAR --> char) to allow Unicode compilation.
* Huge amount of reformating. Code passes checkpatch.pl except for what
* appears to be a checkpatch.pl bug (reported).
* Fixes since last submission.

This code ran various tests for the whole night with no problems seen.

Comments/feedback welcome, but I'm hopefully getting pretty close to
acceptance :-).

-- Charles

[PATCH 01/10] Add yaffs2 file system: Allocation, block handling and bitmapping code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_allocator.c    |  387 ++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_allocator.h    |   30 +++
 fs/yaffs2/yaffs_bitmap.c       |   97 ++++++++++
 fs/yaffs2/yaffs_bitmap.h       |   33 ++++
 fs/yaffs2/yaffs_getblockinfo.h |   35 ++++
 5 files changed, 582 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_allocator.c
 create mode 100644 fs/yaffs2/yaffs_allocator.h
 create mode 100644 fs/yaffs2/yaffs_bitmap.c
 create mode 100644 fs/yaffs2/yaffs_bitmap.h
 create mode 100644 fs/yaffs2/yaffs_getblockinfo.h

diff --git a/fs/yaffs2/yaffs_allocator.c b/fs/yaffs2/yaffs_allocator.c
new file mode 100644
index 0000000..59cce04
--- /dev/null
+++ b/fs/yaffs2/yaffs_allocator.c
@@ -0,0 +1,387 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_allocator.h"
+#include "yaffs_guts.h"
+#include "yaffs_trace.h"
+#include "yportenv.h"
+
+#ifdef CONFIG_YAFFS_KMALLOC_ALLOCATOR
+/* This is an alternative debug allocator. Don't use for production code. */
+
+void yaffs_deinit_raw_tnodes_and_objs(struct yaffs_dev *dev)
+{
+	dev = dev;
+}
+
+void yaffs_init_raw_tnodes_and_objs(struct yaffs_dev *dev)
+{
+	dev = dev;
+}
+
+struct yaffs_tnode *yaffs_alloc_raw_tnode(struct yaffs_dev *dev)
+{
+	return kmalloc(dev->tnode_size, GFP_NOFS);
+}
+
+void yaffs_free_raw_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn)
+{
+	dev = dev;
+	kfree(tn);
+}
+
+void yaffs_init_raw_objs(struct yaffs_dev *dev)
+{
+	dev = dev;
+}
+
+void yaffs_deinit_raw_objs(struct yaffs_dev *dev)
+{
+	dev = dev;
+}
+
+struct yaffs_obj *yaffs_alloc_raw_obj(struct yaffs_dev *dev)
+{
+	dev = dev;
+	return kmalloc(sizeof(struct yaffs_obj));
+}
+
+void yaffs_free_raw_obj(struct yaffs_dev *dev, struct yaffs_obj *obj)
+{
+
+	dev = dev;
+	kfree(obj);
+}
+
+#else
+
+struct yaffs_tnode_list {
+	struct yaffs_tnode_list *next;
+	struct yaffs_tnode *tnodes;
+};
+
+struct yaffs_obj_list {
+	struct yaffs_obj_list *next;
+	struct yaffs_obj *objects;
+};
+
+struct yaffs_allocator {
+	int n_tnodes_created;
+	struct yaffs_tnode *free_tnodes;
+	int n_free_tnodes;
+	struct yaffs_tnode_list *alloc_tnode_list;
+
+	int n_obj_created;
+	struct yaffs_obj *free_objs;
+	int n_free_objects;
+
+	struct yaffs_obj_list *allocated_obj_list;
+};
+
+static void yaffs_deinit_raw_tnodes(struct yaffs_dev *dev)
+{
+	struct yaffs_allocator *allocator =
+	    (struct yaffs_allocator *)dev->allocator;
+	struct yaffs_tnode_list *tmp;
+
+	if (!allocator) {
+		YBUG();
+		return;
+	}
+
+	while (allocator->alloc_tnode_list) {
+		tmp = allocator->alloc_tnode_list->next;
+
+		kfree(allocator->alloc_tnode_list->tnodes);
+		kfree(allocator->alloc_tnode_list);
+		allocator->alloc_tnode_list = tmp;
+	}
+
+	allocator->free_tnodes = NULL;
+	allocator->n_free_tnodes = 0;
+	allocator->n_tnodes_created = 0;
+}
+
+static void yaffs_init_raw_tnodes(struct yaffs_dev *dev)
+{
+	struct yaffs_allocator *allocator = dev->allocator;
+
+	if (allocator) {
+		allocator->alloc_tnode_list = NULL;
+		allocator->free_tnodes = NULL;
+		allocator->n_free_tnodes = 0;
+		allocator->n_tnodes_created = 0;
+	} else {
+		YBUG();
+	}
+}
+
+static int yaffs_create_tnodes(struct yaffs_dev *dev, int n_tnodes)
+{
+	struct yaffs_allocator *allocator =
+	    (struct yaffs_allocator *)dev->allocator;
+	int i;
+	struct yaffs_tnode *new_tnodes;
+	u8 *mem;
+	struct yaffs_tnode *curr;
+	struct yaffs_tnode *next;
+	struct yaffs_tnode_list *tnl;
+
+	if (!allocator) {
+		YBUG();
+		return YAFFS_FAIL;
+	}
+
+	if (n_tnodes < 1)
+		return YAFFS_OK;
+
+	/* make these things */
+	new_tnodes = kmalloc(n_tnodes * dev->tnode_size, GFP_NOFS);
+	mem = (u8 *) new_tnodes;
+
+	if (!new_tnodes) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"yaffs: Could not allocate Tnodes");
+		return YAFFS_FAIL;
+	}
+
+	/* New hookup for wide tnodes */
+	for (i = 0; i < n_tnodes - 1; i++) {
+		curr = (struct yaffs_tnode *)&mem[i * dev->tnode_size];
+		next = (struct yaffs_tnode *)&mem[(i + 1) * dev->tnode_size];
+		curr->internal[0] = next;
+	}
+
+	curr = (struct yaffs_tnode *)&mem[(n_tnodes - 1) * dev->tnode_size];
+	curr->internal[0] = allocator->free_tnodes;
+	allocator->free_tnodes = (struct yaffs_tnode *)mem;
+
+	allocator->n_free_tnodes += n_tnodes;
+	allocator->n_tnodes_created += n_tnodes;
+
+	/* Now add this bunch of tnodes to a list for freeing up.
+	 * NB If we can't add this to the management list it isn't fatal
+	 * but it just means we can't free this bunch of tnodes later.
+	 */
+	tnl = kmalloc(sizeof(struct yaffs_tnode_list), GFP_NOFS);
+	if (!tnl) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"Could not add tnodes to management list");
+		return YAFFS_FAIL;
+	} else {
+		tnl->tnodes = new_tnodes;
+		tnl->next = allocator->alloc_tnode_list;
+		allocator->alloc_tnode_list = tnl;
+	}
+
+	yaffs_trace(YAFFS_TRACE_ALLOCATE, "Tnodes added");
+
+	return YAFFS_OK;
+}
+
+struct yaffs_tnode *yaffs_alloc_raw_tnode(struct yaffs_dev *dev)
+{
+	struct yaffs_allocator *allocator =
+	    (struct yaffs_allocator *)dev->allocator;
+	struct yaffs_tnode *tn = NULL;
+
+	if (!allocator) {
+		YBUG();
+		return NULL;
+	}
+
+	/* If there are none left make more */
+	if (!allocator->free_tnodes)
+		yaffs_create_tnodes(dev, YAFFS_ALLOCATION_NTNODES);
+
+	if (allocator->free_tnodes) {
+		tn = allocator->free_tnodes;
+		allocator->free_tnodes = allocator->free_tnodes->internal[0];
+		allocator->n_free_tnodes--;
+	}
+
+	return tn;
+}
+
+/* FreeTnode frees up a tnode and puts it back on the free list */
+void yaffs_free_raw_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn)
+{
+	struct yaffs_allocator *allocator = dev->allocator;
+
+	if (!allocator) {
+		YBUG();
+		return;
+	}
+
+	if (tn) {
+		tn->internal[0] = allocator->free_tnodes;
+		allocator->free_tnodes = tn;
+		allocator->n_free_tnodes++;
+	}
+	dev->checkpoint_blocks_required = 0;	/* force recalculation */
+}
+
+static void yaffs_init_raw_objs(struct yaffs_dev *dev)
+{
+	struct yaffs_allocator *allocator = dev->allocator;
+
+	if (allocator) {
+		allocator->allocated_obj_list = NULL;
+		allocator->free_objs = NULL;
+		allocator->n_free_objects = 0;
+	} else {
+		YBUG();
+	}
+}
+
+static void yaffs_deinit_raw_objs(struct yaffs_dev *dev)
+{
+	struct yaffs_allocator *allocator = dev->allocator;
+	struct yaffs_obj_list *tmp;
+
+	if (!allocator) {
+		YBUG();
+		return;
+	}
+
+	while (allocator->allocated_obj_list) {
+		tmp = allocator->allocated_obj_list->next;
+		kfree(allocator->allocated_obj_list->objects);
+		kfree(allocator->allocated_obj_list);
+
+		allocator->allocated_obj_list = tmp;
+	}
+
+	allocator->free_objs = NULL;
+	allocator->n_free_objects = 0;
+	allocator->n_obj_created = 0;
+}
+
+static int yaffs_create_free_objs(struct yaffs_dev *dev, int n_obj)
+{
+	struct yaffs_allocator *allocator = dev->allocator;
+	int i;
+	struct yaffs_obj *new_objs;
+	struct yaffs_obj_list *list;
+
+	if (!allocator) {
+		YBUG();
+		return YAFFS_FAIL;
+	}
+
+	if (n_obj < 1)
+		return YAFFS_OK;
+
+	/* make these things */
+	new_objs = kmalloc(n_obj * sizeof(struct yaffs_obj), GFP_NOFS);
+	list = kmalloc(sizeof(struct yaffs_obj_list), GFP_NOFS);
+
+	if (!new_objs || !list) {
+		kfree(new_objs);
+		new_objs = NULL;
+		kfree(list);
+		list = NULL;
+		yaffs_trace(YAFFS_TRACE_ALLOCATE,
+			"Could not allocate more objects");
+		return YAFFS_FAIL;
+	}
+
+	/* Hook them into the free list */
+	for (i = 0; i < n_obj - 1; i++) {
+		new_objs[i].siblings.next =
+		    (struct list_head *)(&new_objs[i + 1]);
+	}
+
+	new_objs[n_obj - 1].siblings.next = (void *)allocator->free_objs;
+	allocator->free_objs = new_objs;
+	allocator->n_free_objects += n_obj;
+	allocator->n_obj_created += n_obj;
+
+	/* Now add this bunch of Objects to a list for freeing up. */
+
+	list->objects = new_objs;
+	list->next = allocator->allocated_obj_list;
+	allocator->allocated_obj_list = list;
+
+	return YAFFS_OK;
+}
+
+struct yaffs_obj *yaffs_alloc_raw_obj(struct yaffs_dev *dev)
+{
+	struct yaffs_obj *obj = NULL;
+	struct yaffs_allocator *allocator = dev->allocator;
+
+	if (!allocator) {
+		YBUG();
+		return obj;
+	}
+
+	/* If there are none left make more */
+	if (!allocator->free_objs)
+		yaffs_create_free_objs(dev, YAFFS_ALLOCATION_NOBJECTS);
+
+	if (allocator->free_objs) {
+		obj = allocator->free_objs;
+		allocator->free_objs =
+		    (struct yaffs_obj *)(allocator->free_objs->siblings.next);
+		allocator->n_free_objects--;
+	}
+
+	return obj;
+}
+
+void yaffs_free_raw_obj(struct yaffs_dev *dev, struct yaffs_obj *obj)
+{
+
+	struct yaffs_allocator *allocator = dev->allocator;
+
+	if (!allocator)
+		YBUG();
+	else {
+		/* Link into the free list. */
+		obj->siblings.next = (struct list_head *)(allocator->free_objs);
+		allocator->free_objs = obj;
+		allocator->n_free_objects++;
+	}
+}
+
+void yaffs_deinit_raw_tnodes_and_objs(struct yaffs_dev *dev)
+{
+	if (dev->allocator) {
+		yaffs_deinit_raw_tnodes(dev);
+		yaffs_deinit_raw_objs(dev);
+
+		kfree(dev->allocator);
+		dev->allocator = NULL;
+	} else {
+		YBUG();
+	}
+}
+
+void yaffs_init_raw_tnodes_and_objs(struct yaffs_dev *dev)
+{
+	struct yaffs_allocator *allocator;
+
+	if (!dev->allocator) {
+		allocator = kmalloc(sizeof(struct yaffs_allocator), GFP_NOFS);
+		if (allocator) {
+			dev->allocator = allocator;
+			yaffs_init_raw_tnodes(dev);
+			yaffs_init_raw_objs(dev);
+		}
+	} else {
+		YBUG();
+	}
+}
+
+#endif
diff --git a/fs/yaffs2/yaffs_allocator.h b/fs/yaffs2/yaffs_allocator.h
new file mode 100644
index 0000000..4d5f2ae
--- /dev/null
+++ b/fs/yaffs2/yaffs_allocator.h
@@ -0,0 +1,30 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_ALLOCATOR_H__
+#define __YAFFS_ALLOCATOR_H__
+
+#include "yaffs_guts.h"
+
+void yaffs_init_raw_tnodes_and_objs(struct yaffs_dev *dev);
+void yaffs_deinit_raw_tnodes_and_objs(struct yaffs_dev *dev);
+
+struct yaffs_tnode *yaffs_alloc_raw_tnode(struct yaffs_dev *dev);
+void yaffs_free_raw_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn);
+
+struct yaffs_obj *yaffs_alloc_raw_obj(struct yaffs_dev *dev);
+void yaffs_free_raw_obj(struct yaffs_dev *dev, struct yaffs_obj *obj);
+
+#endif
diff --git a/fs/yaffs2/yaffs_bitmap.c b/fs/yaffs2/yaffs_bitmap.c
new file mode 100644
index 0000000..dc673e8
--- /dev/null
+++ b/fs/yaffs2/yaffs_bitmap.c
@@ -0,0 +1,97 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_bitmap.h"
+#include "yaffs_trace.h"
+/*
+ * Chunk bitmap manipulations
+ */
+
+static inline u8 *yaffs_block_bits(struct yaffs_dev *dev, int blk)
+{
+	if (blk < dev->internal_start_block || blk > dev->internal_end_block) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"BlockBits block %d is not valid",
+			blk);
+		YBUG();
+	}
+	return dev->chunk_bits +
+	    (dev->chunk_bit_stride * (blk - dev->internal_start_block));
+}
+
+void yaffs_verify_chunk_bit_id(struct yaffs_dev *dev, int blk, int chunk)
+{
+	if (blk < dev->internal_start_block || blk > dev->internal_end_block ||
+	    chunk < 0 || chunk >= dev->param.chunks_per_block) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"Chunk Id (%d:%d) invalid",
+			blk, chunk);
+		YBUG();
+	}
+}
+
+void yaffs_clear_chunk_bits(struct yaffs_dev *dev, int blk)
+{
+	u8 *blk_bits = yaffs_block_bits(dev, blk);
+
+	memset(blk_bits, 0, dev->chunk_bit_stride);
+}
+
+void yaffs_clear_chunk_bit(struct yaffs_dev *dev, int blk, int chunk)
+{
+	u8 *blk_bits = yaffs_block_bits(dev, blk);
+
+	yaffs_verify_chunk_bit_id(dev, blk, chunk);
+	blk_bits[chunk / 8] &= ~(1 << (chunk & 7));
+}
+
+void yaffs_set_chunk_bit(struct yaffs_dev *dev, int blk, int chunk)
+{
+	u8 *blk_bits = yaffs_block_bits(dev, blk);
+
+	yaffs_verify_chunk_bit_id(dev, blk, chunk);
+	blk_bits[chunk / 8] |= (1 << (chunk & 7));
+}
+
+int yaffs_check_chunk_bit(struct yaffs_dev *dev, int blk, int chunk)
+{
+	u8 *blk_bits = yaffs_block_bits(dev, blk);
+
+	yaffs_verify_chunk_bit_id(dev, blk, chunk);
+	return (blk_bits[chunk / 8] & (1 << (chunk & 7))) ? 1 : 0;
+}
+
+int yaffs_still_some_chunks(struct yaffs_dev *dev, int blk)
+{
+	u8 *blk_bits = yaffs_block_bits(dev, blk);
+	int i;
+
+	for (i = 0; i < dev->chunk_bit_stride; i++) {
+		if (*blk_bits)
+			return 1;
+		blk_bits++;
+	}
+	return 0;
+}
+
+int yaffs_count_chunk_bits(struct yaffs_dev *dev, int blk)
+{
+	u8 *blk_bits = yaffs_block_bits(dev, blk);
+	int i;
+	int n = 0;
+
+	for (i = 0; i < dev->chunk_bit_stride; i++, blk_bits++)
+		n += hweight8(*blk_bits);
+
+	return n;
+}
diff --git a/fs/yaffs2/yaffs_bitmap.h b/fs/yaffs2/yaffs_bitmap.h
new file mode 100644
index 0000000..cf9ea58
--- /dev/null
+++ b/fs/yaffs2/yaffs_bitmap.h
@@ -0,0 +1,33 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+/*
+ * Chunk bitmap manipulations
+ */
+
+#ifndef __YAFFS_BITMAP_H__
+#define __YAFFS_BITMAP_H__
+
+#include "yaffs_guts.h"
+
+void yaffs_verify_chunk_bit_id(struct yaffs_dev *dev, int blk, int chunk);
+void yaffs_clear_chunk_bits(struct yaffs_dev *dev, int blk);
+void yaffs_clear_chunk_bit(struct yaffs_dev *dev, int blk, int chunk);
+void yaffs_set_chunk_bit(struct yaffs_dev *dev, int blk, int chunk);
+int yaffs_check_chunk_bit(struct yaffs_dev *dev, int blk, int chunk);
+int yaffs_still_some_chunks(struct yaffs_dev *dev, int blk);
+int yaffs_count_chunk_bits(struct yaffs_dev *dev, int blk);
+
+#endif
diff --git a/fs/yaffs2/yaffs_getblockinfo.h b/fs/yaffs2/yaffs_getblockinfo.h
new file mode 100644
index 0000000..d87acbd
--- /dev/null
+++ b/fs/yaffs2/yaffs_getblockinfo.h
@@ -0,0 +1,35 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_GETBLOCKINFO_H__
+#define __YAFFS_GETBLOCKINFO_H__
+
+#include "yaffs_guts.h"
+#include "yaffs_trace.h"
+
+/* Function to manipulate block info */
+static inline struct yaffs_block_info *yaffs_get_block_info(struct yaffs_dev
+							      *dev, int blk)
+{
+	if (blk < dev->internal_start_block || blk > dev->internal_end_block) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"**>> yaffs: get_block_info block %d is not valid",
+			blk);
+		YBUG();
+	}
+	return &dev->block_info[blk - dev->internal_start_block];
+}
+
+#endif
-- 
1.7.1

Re: [PATCH 01/10] Add yaffs2 file system: Allocation, block handling and bitmapping code

[Ryan Mallon]

On 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Hi Charles,

A few comments below.

~Ryan

> ---
>  fs/yaffs2/yaffs_allocator.c    |  387 ++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_allocator.h    |   30 +++
>  fs/yaffs2/yaffs_bitmap.c       |   97 ++++++++++
>  fs/yaffs2/yaffs_bitmap.h       |   33 ++++
>  fs/yaffs2/yaffs_getblockinfo.h |   35 ++++
>  5 files changed, 582 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_allocator.c
>  create mode 100644 fs/yaffs2/yaffs_allocator.h
>  create mode 100644 fs/yaffs2/yaffs_bitmap.c
>  create mode 100644 fs/yaffs2/yaffs_bitmap.h
>  create mode 100644 fs/yaffs2/yaffs_getblockinfo.h
> 
> diff --git a/fs/yaffs2/yaffs_allocator.c b/fs/yaffs2/yaffs_allocator.c
> new file mode 100644
> index 0000000..59cce04
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_allocator.c
> @@ -0,0 +1,387 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_allocator.h"
> +#include "yaffs_guts.h"
> +#include "yaffs_trace.h"
> +#include "yportenv.h"
> +
> +#ifdef CONFIG_YAFFS_KMALLOC_ALLOCATOR

I still don't understand what this is for. It's not in Kconfig. If it is
a debugging feature then there should be a comment to that effect.

Also, if you do want to keep the two alternative versions of the code
here, it may be better to put them in separate files and use Makefile
rules to include the correct one.

> +/* This is an alternative debug allocator. Don't use for production code. */
> +
> +void yaffs_deinit_raw_tnodes_and_objs(struct yaffs_dev *dev)

You can use the __always_unused attribute instead of the self
assignments. Do you actually get warnings without the assignment?

> +{
> +	dev = dev;
> +}
> +
> +void yaffs_init_raw_tnodes_and_objs(struct yaffs_dev *dev)
> +{
> +	dev = dev;
> +}
> +
> +struct yaffs_tnode *yaffs_alloc_raw_tnode(struct yaffs_dev *dev)
> +{
> +	return kmalloc(dev->tnode_size, GFP_NOFS);
> +}
> +
> +void yaffs_free_raw_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn)
> +{
> +	dev = dev;
> +	kfree(tn);
> +}
> +
> +void yaffs_init_raw_objs(struct yaffs_dev *dev)
> +{
> +	dev = dev;
> +}
> +
> +void yaffs_deinit_raw_objs(struct yaffs_dev *dev)
> +{
> +	dev = dev;
> +}
> +
> +struct yaffs_obj *yaffs_alloc_raw_obj(struct yaffs_dev *dev)
> +{
> +	dev = dev;
> +	return kmalloc(sizeof(struct yaffs_obj));
> +}
> +
> +void yaffs_free_raw_obj(struct yaffs_dev *dev, struct yaffs_obj *obj)
> +{
> +
> +	dev = dev;
> +	kfree(obj);
> +}
> +
> +#else
> +
> +struct yaffs_tnode_list {
> +	struct yaffs_tnode_list *next;
> +	struct yaffs_tnode *tnodes;
> +};
> +
> +struct yaffs_obj_list {
> +	struct yaffs_obj_list *next;
> +	struct yaffs_obj *objects;
> +};
> +
> +struct yaffs_allocator {
> +	int n_tnodes_created;
> +	struct yaffs_tnode *free_tnodes;
> +	int n_free_tnodes;
> +	struct yaffs_tnode_list *alloc_tnode_list;
> +
> +	int n_obj_created;
> +	struct yaffs_obj *free_objs;
> +	int n_free_objects;
> +
> +	struct yaffs_obj_list *allocated_obj_list;
> +};
> +
> +static void yaffs_deinit_raw_tnodes(struct yaffs_dev *dev)
> +{
> +	struct yaffs_allocator *allocator =
> +	    (struct yaffs_allocator *)dev->allocator;

yaffs_dev->allocator is type void *. Is this necessary? It looks like it
is always used as struct yaffs_allocator, so would be better to change
the type and remove all of the casting.

> +	struct yaffs_tnode_list *tmp;
> +
> +	if (!allocator) {
> +		YBUG();
> +		return;
> +	}

You don't need this bug, the dereference of allocator below will oops
with all the same information as bug.

> +	while (allocator->alloc_tnode_list) {
> +		tmp = allocator->alloc_tnode_list->next;
> +
> +		kfree(allocator->alloc_tnode_list->tnodes);
> +		kfree(allocator->alloc_tnode_list);
> +		allocator->alloc_tnode_list = tmp;
> +	}
> +
> +	allocator->free_tnodes = NULL;
> +	allocator->n_free_tnodes = 0;
> +	allocator->n_tnodes_created = 0;
> +}
> +
> +static void yaffs_init_raw_tnodes(struct yaffs_dev *dev)
> +{
> +	struct yaffs_allocator *allocator = dev->allocator;
> +
> +	if (allocator) {
> +		allocator->alloc_tnode_list = NULL;
> +		allocator->free_tnodes = NULL;
> +		allocator->n_free_tnodes = 0;
> +		allocator->n_tnodes_created = 0;
> +	} else {
> +		YBUG();
> +	}

Again, you don't need the explicit bug. Just dereference allocator and
you will oops if it is null. There are several other places where bug
can be removed also.

> +}
> +
> +static int yaffs_create_tnodes(struct yaffs_dev *dev, int n_tnodes)
> +{
> +	struct yaffs_allocator *allocator =
> +	    (struct yaffs_allocator *)dev->allocator;
> +	int i;
> +	struct yaffs_tnode *new_tnodes;
> +	u8 *mem;
> +	struct yaffs_tnode *curr;
> +	struct yaffs_tnode *next;
> +	struct yaffs_tnode_list *tnl;
> +
> +	if (!allocator) {
> +		YBUG();
> +		return YAFFS_FAIL;
> +	}
> +
> +	if (n_tnodes < 1)
> +		return YAFFS_OK;
> +
> +	/* make these things */
> +	new_tnodes = kmalloc(n_tnodes * dev->tnode_size, GFP_NOFS);
> +	mem = (u8 *) new_tnodes;
> +
> +	if (!new_tnodes) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"yaffs: Could not allocate Tnodes");
> +		return YAFFS_FAIL;
> +	}
> +
> +	/* New hookup for wide tnodes */
> +	for (i = 0; i < n_tnodes - 1; i++) {
> +		curr = (struct yaffs_tnode *)&mem[i * dev->tnode_size];
> +		next = (struct yaffs_tnode *)&mem[(i + 1) * dev->tnode_size];

mem is declared u8 * but is being used as type (struct yaffs_tnode *). I
realise that pointer addition won't work correctly because you use
dev->tnode_size rather than sizeof(struct yaffs_tnode), but is there a
cleaner way to do this without the casting?

> +		curr->internal[0] = next;
> +	}
> +
> +	curr = (struct yaffs_tnode *)&mem[(n_tnodes - 1) * dev->tnode_size];
> +	curr->internal[0] = allocator->free_tnodes;
> +	allocator->free_tnodes = (struct yaffs_tnode *)mem;
> +
> +	allocator->n_free_tnodes += n_tnodes;
> +	allocator->n_tnodes_created += n_tnodes;
> +
> +	/* Now add this bunch of tnodes to a list for freeing up.
> +	 * NB If we can't add this to the management list it isn't fatal
> +	 * but it just means we can't free this bunch of tnodes later.
> +	 */
> +	tnl = kmalloc(sizeof(struct yaffs_tnode_list), GFP_NOFS);
> +	if (!tnl) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"Could not add tnodes to management list");

Should new_nodes be freed here?

> +		return YAFFS_FAIL;
> +	} else {
> +		tnl->tnodes = new_tnodes;
> +		tnl->next = allocator->alloc_tnode_list;
> +		allocator->alloc_tnode_list = tnl;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_ALLOCATE, "Tnodes added");
> +
> +	return YAFFS_OK;
> +}
> +
> +struct yaffs_tnode *yaffs_alloc_raw_tnode(struct yaffs_dev *dev)
> +{
> +	struct yaffs_allocator *allocator =
> +	    (struct yaffs_allocator *)dev->allocator;
> +	struct yaffs_tnode *tn = NULL;
> +
> +	if (!allocator) {
> +		YBUG();
> +		return NULL;
> +	}
> +
> +	/* If there are none left make more */
> +	if (!allocator->free_tnodes)
> +		yaffs_create_tnodes(dev, YAFFS_ALLOCATION_NTNODES);
> +
> +	if (allocator->free_tnodes) {
> +		tn = allocator->free_tnodes;
> +		allocator->free_tnodes = allocator->free_tnodes->internal[0];
> +		allocator->n_free_tnodes--;
> +	}
> +
> +	return tn;
> +}
> +
> +/* FreeTnode frees up a tnode and puts it back on the free list */
> +void yaffs_free_raw_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn)
> +{
> +	struct yaffs_allocator *allocator = dev->allocator;
> +
> +	if (!allocator) {
> +		YBUG();
> +		return;
> +	}
> +	if (tn) {
> +		tn->internal[0] = allocator->free_tnodes;
> +		allocator->free_tnodes = tn;
> +		allocator->n_free_tnodes++;
> +	}
> +	dev->checkpoint_blocks_required = 0;	/* force recalculation */
> +}
> +
> +static void yaffs_init_raw_objs(struct yaffs_dev *dev)
> +{
> +	struct yaffs_allocator *allocator = dev->allocator;
> +
> +	if (allocator) {
> +		allocator->allocated_obj_list = NULL;
> +		allocator->free_objs = NULL;
> +		allocator->n_free_objects = 0;
> +	} else {
> +		YBUG();
> +	}
> +}
> +
> +static void yaffs_deinit_raw_objs(struct yaffs_dev *dev)
> +{
> +	struct yaffs_allocator *allocator = dev->allocator;
> +	struct yaffs_obj_list *tmp;
> +
> +	if (!allocator) {
> +		YBUG();
> +		return;
> +	}
> +
> +	while (allocator->allocated_obj_list) {
> +		tmp = allocator->allocated_obj_list->next;
> +		kfree(allocator->allocated_obj_list->objects);
> +		kfree(allocator->allocated_obj_list);
> +
> +		allocator->allocated_obj_list = tmp;
> +	}
> +
> +	allocator->free_objs = NULL;
> +	allocator->n_free_objects = 0;
> +	allocator->n_obj_created = 0;
> +}
> +
> +static int yaffs_create_free_objs(struct yaffs_dev *dev, int n_obj)
> +{
> +	struct yaffs_allocator *allocator = dev->allocator;
> +	int i;
> +	struct yaffs_obj *new_objs;
> +	struct yaffs_obj_list *list;
> +
> +	if (!allocator) {
> +		YBUG();
> +		return YAFFS_FAIL;
> +	}
> +
> +	if (n_obj < 1)
> +		return YAFFS_OK;
> +
> +	/* make these things */
> +	new_objs = kmalloc(n_obj * sizeof(struct yaffs_obj), GFP_NOFS);
> +	list = kmalloc(sizeof(struct yaffs_obj_list), GFP_NOFS);
> +
> +	if (!new_objs || !list) {
> +		kfree(new_objs);
> +		new_objs = NULL;
> +		kfree(list);
> +		list = NULL;

You don't need to set new_objs and list to NULL here.

> +		yaffs_trace(YAFFS_TRACE_ALLOCATE,
> +			"Could not allocate more objects");
> +		return YAFFS_FAIL;
> +	}
> +
> +	/* Hook them into the free list */
> +	for (i = 0; i < n_obj - 1; i++) {
> +		new_objs[i].siblings.next =
> +		    (struct list_head *)(&new_objs[i + 1]);

This cast looks like you are doing something with odd with list_head.

> +	}
> +
> +	new_objs[n_obj - 1].siblings.next = (void *)allocator->free_objs;

You shouldn't need the void * cast here.

> +	allocator->free_objs = new_objs;
> +	allocator->n_free_objects += n_obj;
> +	allocator->n_obj_created += n_obj;
> +
> +	/* Now add this bunch of Objects to a list for freeing up. */
> +
> +	list->objects = new_objs;
> +	list->next = allocator->allocated_obj_list;
> +	allocator->allocated_obj_list = list;
> +
> +	return YAFFS_OK;
> +}
> +
> +struct yaffs_obj *yaffs_alloc_raw_obj(struct yaffs_dev *dev)
> +{
> +	struct yaffs_obj *obj = NULL;
> +	struct yaffs_allocator *allocator = dev->allocator;
> +
> +	if (!allocator) {
> +		YBUG();
> +		return obj;
> +	}
> +
> +	/* If there are none left make more */
> +	if (!allocator->free_objs)
> +		yaffs_create_free_objs(dev, YAFFS_ALLOCATION_NOBJECTS);
> +
> +	if (allocator->free_objs) {
> +		obj = allocator->free_objs;
> +		allocator->free_objs =
> +		    (struct yaffs_obj *)(allocator->free_objs->siblings.next);
> +		allocator->n_free_objects--;
> +	}
> +
> +	return obj;
> +}
> +
> +void yaffs_free_raw_obj(struct yaffs_dev *dev, struct yaffs_obj *obj)
> +{
> +
> +	struct yaffs_allocator *allocator = dev->allocator;
> +
> +	if (!allocator)
> +		YBUG();
> +	else {
> +		/* Link into the free list. */
> +		obj->siblings.next = (struct list_head *)(allocator->free_objs);

More list_head weirdness.

> +		allocator->free_objs = obj;
> +		allocator->n_free_objects++;
> +	}
> +}
> +
> +void yaffs_deinit_raw_tnodes_and_objs(struct yaffs_dev *dev)
> +{
> +	if (dev->allocator) {
> +		yaffs_deinit_raw_tnodes(dev);
> +		yaffs_deinit_raw_objs(dev);
> +
> +		kfree(dev->allocator);
> +		dev->allocator = NULL;
> +	} else {
> +		YBUG();
> +	}
> +}
> +
> +void yaffs_init_raw_tnodes_and_objs(struct yaffs_dev *dev)
> +{
> +	struct yaffs_allocator *allocator;
> +
> +	if (!dev->allocator) {
> +		allocator = kmalloc(sizeof(struct yaffs_allocator), GFP_NOFS);
> +		if (allocator) {
> +			dev->allocator = allocator;
> +			yaffs_init_raw_tnodes(dev);
> +			yaffs_init_raw_objs(dev);
> +		}
> +	} else {
> +		YBUG();
> +	}
> +}
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_allocator.h b/fs/yaffs2/yaffs_allocator.h
> new file mode 100644
> index 0000000..4d5f2ae
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_allocator.h
> @@ -0,0 +1,30 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_ALLOCATOR_H__
> +#define __YAFFS_ALLOCATOR_H__
> +
> +#include "yaffs_guts.h"
> +
> +void yaffs_init_raw_tnodes_and_objs(struct yaffs_dev *dev);
> +void yaffs_deinit_raw_tnodes_and_objs(struct yaffs_dev *dev);
> +
> +struct yaffs_tnode *yaffs_alloc_raw_tnode(struct yaffs_dev *dev);
> +void yaffs_free_raw_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn);
> +
> +struct yaffs_obj *yaffs_alloc_raw_obj(struct yaffs_dev *dev);
> +void yaffs_free_raw_obj(struct yaffs_dev *dev, struct yaffs_obj *obj);
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_bitmap.c b/fs/yaffs2/yaffs_bitmap.c
> new file mode 100644
> index 0000000..dc673e8
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_bitmap.c
> @@ -0,0 +1,97 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_bitmap.h"
> +#include "yaffs_trace.h"
> +/*
> + * Chunk bitmap manipulations
> + */
> +
> +static inline u8 *yaffs_block_bits(struct yaffs_dev *dev, int blk)
> +{
> +	if (blk < dev->internal_start_block || blk > dev->internal_end_block) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"BlockBits block %d is not valid",
> +			blk);
> +		YBUG();
> +	}
> +	return dev->chunk_bits +
> +	    (dev->chunk_bit_stride * (blk - dev->internal_start_block));
> +}
> +
> +void yaffs_verify_chunk_bit_id(struct yaffs_dev *dev, int blk, int chunk)
> +{
> +	if (blk < dev->internal_start_block || blk > dev->internal_end_block ||
> +	    chunk < 0 || chunk >= dev->param.chunks_per_block) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"Chunk Id (%d:%d) invalid",
> +			blk, chunk);
> +		YBUG();
> +	}
> +}
> +
> +void yaffs_clear_chunk_bits(struct yaffs_dev *dev, int blk)
> +{
> +	u8 *blk_bits = yaffs_block_bits(dev, blk);
> +
> +	memset(blk_bits, 0, dev->chunk_bit_stride);
> +}
> +
> +void yaffs_clear_chunk_bit(struct yaffs_dev *dev, int blk, int chunk)
> +{
> +	u8 *blk_bits = yaffs_block_bits(dev, blk);
> +
> +	yaffs_verify_chunk_bit_id(dev, blk, chunk);
> +	blk_bits[chunk / 8] &= ~(1 << (chunk & 7));
> +}
> +
> +void yaffs_set_chunk_bit(struct yaffs_dev *dev, int blk, int chunk)
> +{
> +	u8 *blk_bits = yaffs_block_bits(dev, blk);
> +
> +	yaffs_verify_chunk_bit_id(dev, blk, chunk);
> +	blk_bits[chunk / 8] |= (1 << (chunk & 7));
> +}
> +
> +int yaffs_check_chunk_bit(struct yaffs_dev *dev, int blk, int chunk)
> +{
> +	u8 *blk_bits = yaffs_block_bits(dev, blk);
> +
> +	yaffs_verify_chunk_bit_id(dev, blk, chunk);
> +	return (blk_bits[chunk / 8] & (1 << (chunk & 7))) ? 1 : 0;
> +}
> +
> +int yaffs_still_some_chunks(struct yaffs_dev *dev, int blk)
> +{
> +	u8 *blk_bits = yaffs_block_bits(dev, blk);
> +	int i;
> +
> +	for (i = 0; i < dev->chunk_bit_stride; i++) {
> +		if (*blk_bits)
> +			return 1;
> +		blk_bits++;
> +	}
> +	return 0;
> +}
> +
> +int yaffs_count_chunk_bits(struct yaffs_dev *dev, int blk)
> +{
> +	u8 *blk_bits = yaffs_block_bits(dev, blk);
> +	int i;
> +	int n = 0;
> +
> +	for (i = 0; i < dev->chunk_bit_stride; i++, blk_bits++)
> +		n += hweight8(*blk_bits);
> +
> +	return n;
> +}
> diff --git a/fs/yaffs2/yaffs_bitmap.h b/fs/yaffs2/yaffs_bitmap.h
> new file mode 100644
> index 0000000..cf9ea58
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_bitmap.h
> @@ -0,0 +1,33 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +/*
> + * Chunk bitmap manipulations
> + */
> +
> +#ifndef __YAFFS_BITMAP_H__
> +#define __YAFFS_BITMAP_H__
> +
> +#include "yaffs_guts.h"
> +
> +void yaffs_verify_chunk_bit_id(struct yaffs_dev *dev, int blk, int chunk);
> +void yaffs_clear_chunk_bits(struct yaffs_dev *dev, int blk);
> +void yaffs_clear_chunk_bit(struct yaffs_dev *dev, int blk, int chunk);
> +void yaffs_set_chunk_bit(struct yaffs_dev *dev, int blk, int chunk);
> +int yaffs_check_chunk_bit(struct yaffs_dev *dev, int blk, int chunk);
> +int yaffs_still_some_chunks(struct yaffs_dev *dev, int blk);
> +int yaffs_count_chunk_bits(struct yaffs_dev *dev, int blk);
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_getblockinfo.h b/fs/yaffs2/yaffs_getblockinfo.h
> new file mode 100644
> index 0000000..d87acbd
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_getblockinfo.h
> @@ -0,0 +1,35 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_GETBLOCKINFO_H__
> +#define __YAFFS_GETBLOCKINFO_H__
> +
> +#include "yaffs_guts.h"
> +#include "yaffs_trace.h"
> +
> +/* Function to manipulate block info */
> +static inline struct yaffs_block_info *yaffs_get_block_info(struct yaffs_dev
> +							      *dev, int blk)
> +{
> +	if (blk < dev->internal_start_block || blk > dev->internal_end_block) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"**>> yaffs: get_block_info block %d is not valid",
> +			blk);
> +		YBUG();
> +	}
> +	return &dev->block_info[blk - dev->internal_start_block];
> +}
> +
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

Re: [PATCH 01/10] Add yaffs2 file system: Allocation, block handling and bitmapping code

[David Daney]

On 01/19/2011 12:25 PM, Ryan Mallon wrote:
> On 01/14/2011 04:06 PM, Charles Manning wrote:
[...]
>> +	if (!allocator) {
>> +		YBUG();
>> +		return;
>> +	}
>
> You don't need this bug, the dereference of allocator below will oops
> with all the same information as bug.
>

Is that true for nommu systems too?

David Daney

Re: [PATCH 01/10] Add yaffs2 file system: Allocation, block handling and bitmapping code

[Ryan Mallon]

On 01/20/2011 09:37 AM, David Daney wrote:
> On 01/19/2011 12:25 PM, Ryan Mallon wrote:
>> On 01/14/2011 04:06 PM, Charles Manning wrote:
> [...]
>>> +    if (!allocator) {
>>> +        YBUG();
>>> +        return;
>>> +    }
>>
>> You don't need this bug, the dereference of allocator below will oops
>> with all the same information as bug.
>>
> 
> Is that true for nommu systems too?

Actually, I'm not too sure. I understood that best practice was to avoid
putting BUG in places that will normally oops. Maybe someone can shed
some light on this?

~Ryan

-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 02/10] Add yaffs2 file system: Attribute and xattrib handling code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_attribs.c |  124 +++++++++++++++++++++++++++
 fs/yaffs2/yaffs_attribs.h |   28 ++++++
 fs/yaffs2/yaffs_nameval.c |  204 +++++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_nameval.h |   28 ++++++
 4 files changed, 384 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_attribs.c
 create mode 100644 fs/yaffs2/yaffs_attribs.h
 create mode 100644 fs/yaffs2/yaffs_nameval.c
 create mode 100644 fs/yaffs2/yaffs_nameval.h

diff --git a/fs/yaffs2/yaffs_attribs.c b/fs/yaffs2/yaffs_attribs.c
new file mode 100644
index 0000000..9b47d37
--- /dev/null
+++ b/fs/yaffs2/yaffs_attribs.c
@@ -0,0 +1,124 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_guts.h"
+#include "yaffs_attribs.h"
+
+void yaffs_load_attribs(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh)
+{
+	obj->yst_uid = oh->yst_uid;
+	obj->yst_gid = oh->yst_gid;
+	obj->yst_atime = oh->yst_atime;
+	obj->yst_mtime = oh->yst_mtime;
+	obj->yst_ctime = oh->yst_ctime;
+	obj->yst_rdev = oh->yst_rdev;
+}
+
+void yaffs_load_attribs_oh(struct yaffs_obj_hdr *oh, struct yaffs_obj *obj)
+{
+	oh->yst_uid = obj->yst_uid;
+	oh->yst_gid = obj->yst_gid;
+	oh->yst_atime = obj->yst_atime;
+	oh->yst_mtime = obj->yst_mtime;
+	oh->yst_ctime = obj->yst_ctime;
+	oh->yst_rdev = obj->yst_rdev;
+
+}
+
+void yaffs_load_current_time(struct yaffs_obj *obj, int do_a, int do_c)
+{
+	obj->yst_mtime = Y_CURRENT_TIME;
+	if (do_a)
+		obj->yst_atime = obj->yst_mtime;
+	if (do_c)
+		obj->yst_ctime = obj->yst_mtime;
+}
+
+void yaffs_attribs_init(struct yaffs_obj *obj, u32 gid, u32 uid, u32 rdev)
+{
+	yaffs_load_current_time(obj, 1, 1);
+	obj->yst_rdev = rdev;
+	obj->yst_uid = uid;
+	obj->yst_gid = gid;
+}
+
+loff_t yaffs_get_file_size(struct yaffs_obj *obj)
+{
+	YCHAR *alias = NULL;
+	obj = yaffs_get_equivalent_obj(obj);
+
+	switch (obj->variant_type) {
+	case YAFFS_OBJECT_TYPE_FILE:
+		return obj->variant.file_variant.file_size;
+	case YAFFS_OBJECT_TYPE_SYMLINK:
+		alias = obj->variant.symlink_variant.alias;
+		if (!alias)
+			return 0;
+		return strnlen(alias, YAFFS_MAX_ALIAS_LENGTH);
+	default:
+		return 0;
+	}
+}
+
+int yaffs_set_attribs(struct yaffs_obj *obj, struct iattr *attr)
+{
+	unsigned int valid = attr->ia_valid;
+
+	if (valid & ATTR_MODE)
+		obj->yst_mode = attr->ia_mode;
+	if (valid & ATTR_UID)
+		obj->yst_uid = attr->ia_uid;
+	if (valid & ATTR_GID)
+		obj->yst_gid = attr->ia_gid;
+
+	if (valid & ATTR_ATIME)
+		obj->yst_atime = Y_TIME_CONVERT(attr->ia_atime);
+	if (valid & ATTR_CTIME)
+		obj->yst_ctime = Y_TIME_CONVERT(attr->ia_ctime);
+	if (valid & ATTR_MTIME)
+		obj->yst_mtime = Y_TIME_CONVERT(attr->ia_mtime);
+
+	if (valid & ATTR_SIZE)
+		yaffs_resize_file(obj, attr->ia_size);
+
+	yaffs_update_oh(obj, NULL, 1, 0, 0, NULL);
+
+	return YAFFS_OK;
+
+}
+
+int yaffs_get_attribs(struct yaffs_obj *obj, struct iattr *attr)
+{
+	unsigned int valid = 0;
+
+	attr->ia_mode = obj->yst_mode;
+	valid |= ATTR_MODE;
+	attr->ia_uid = obj->yst_uid;
+	valid |= ATTR_UID;
+	attr->ia_gid = obj->yst_gid;
+	valid |= ATTR_GID;
+
+	Y_TIME_CONVERT(attr->ia_atime) = obj->yst_atime;
+	valid |= ATTR_ATIME;
+	Y_TIME_CONVERT(attr->ia_ctime) = obj->yst_ctime;
+	valid |= ATTR_CTIME;
+	Y_TIME_CONVERT(attr->ia_mtime) = obj->yst_mtime;
+	valid |= ATTR_MTIME;
+
+	attr->ia_size = yaffs_get_file_size(obj);
+	valid |= ATTR_SIZE;
+
+	attr->ia_valid = valid;
+
+	return YAFFS_OK;
+}
diff --git a/fs/yaffs2/yaffs_attribs.h b/fs/yaffs2/yaffs_attribs.h
new file mode 100644
index 0000000..33d541d
--- /dev/null
+++ b/fs/yaffs2/yaffs_attribs.h
@@ -0,0 +1,28 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_ATTRIBS_H__
+#define __YAFFS_ATTRIBS_H__
+
+#include "yaffs_guts.h"
+
+void yaffs_load_attribs(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh);
+void yaffs_load_attribs_oh(struct yaffs_obj_hdr *oh, struct yaffs_obj *obj);
+void yaffs_attribs_init(struct yaffs_obj *obj, u32 gid, u32 uid, u32 rdev);
+void yaffs_load_current_time(struct yaffs_obj *obj, int do_a, int do_c);
+int yaffs_set_attribs(struct yaffs_obj *obj, struct iattr *attr);
+int yaffs_get_attribs(struct yaffs_obj *obj, struct iattr *attr);
+
+#endif
diff --git a/fs/yaffs2/yaffs_nameval.c b/fs/yaffs2/yaffs_nameval.c
new file mode 100644
index 0000000..18c30b3
--- /dev/null
+++ b/fs/yaffs2/yaffs_nameval.c
@@ -0,0 +1,204 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * This simple implementation of a name-value store assumes a small number of
+* values and fits into a small finite buffer.
+ *
+ * Each attribute is stored as a record:
+ *  sizeof(int) bytes   record size.
+ *  strnlen+1 bytes name null terminated.
+ *  nbytes    value.
+ *  ----------
+ *  total size  stored in record size
+ *
+ * This code has not been tested with unicode yet.
+ */
+
+#include "yaffs_nameval.h"
+
+#include "yportenv.h"
+
+static int nval_find(const char *xb, int xb_size, const YCHAR *name,
+		     int *exist_size)
+{
+	int pos = 0;
+	int size;
+
+	memcpy(&size, xb, sizeof(int));
+	while (size > 0 && (size < xb_size) && (pos + size < xb_size)) {
+		if (strncmp
+		    ((YCHAR *) (xb + pos + sizeof(int)), name, size) == 0) {
+			if (exist_size)
+				*exist_size = size;
+			return pos;
+		}
+		pos += size;
+		if (pos < xb_size - sizeof(int))
+			memcpy(&size, xb + pos, sizeof(int));
+		else
+			size = 0;
+	}
+	if (exist_size)
+		*exist_size = 0;
+	return -1;
+}
+
+static int nval_used(const char *xb, int xb_size)
+{
+	int pos = 0;
+	int size;
+
+	memcpy(&size, xb + pos, sizeof(int));
+	while (size > 0 && (size < xb_size) && (pos + size < xb_size)) {
+		pos += size;
+		if (pos < xb_size - sizeof(int))
+			memcpy(&size, xb + pos, sizeof(int));
+		else
+			size = 0;
+	}
+	return pos;
+}
+
+int nval_del(char *xb, int xb_size, const YCHAR *name)
+{
+	int pos = nval_find(xb, xb_size, name, NULL);
+	int size;
+
+	if (pos >= 0 && pos < xb_size) {
+		/* Find size, shift rest over this record,
+		 * then zero out the rest of buffer */
+		memcpy(&size, xb + pos, sizeof(int));
+		memcpy(xb + pos, xb + pos + size, xb_size - (pos + size));
+		memset(xb + (xb_size - size), 0, size);
+		return 0;
+	} else {
+		return -ENODATA;
+	}
+}
+
+int nval_set(char *xb, int xb_size, const YCHAR *name, const char *buf,
+		int bsize, int flags)
+{
+	int pos;
+	int namelen = strnlen(name, xb_size);
+	int reclen;
+	int size_exist = 0;
+	int space;
+	int start;
+
+	pos = nval_find(xb, xb_size, name, &size_exist);
+
+	if (flags & XATTR_CREATE && pos >= 0)
+		return -EEXIST;
+	if (flags & XATTR_REPLACE && pos < 0)
+		return -ENODATA;
+
+	start = nval_used(xb, xb_size);
+	space = xb_size - start + size_exist;
+
+	reclen = (sizeof(int) + namelen + 1 + bsize);
+
+	if (reclen > space)
+		return -ENOSPC;
+
+	if (pos >= 0) {
+		nval_del(xb, xb_size, name);
+		start = nval_used(xb, xb_size);
+	}
+
+	pos = start;
+
+	memcpy(xb + pos, &reclen, sizeof(int));
+	pos += sizeof(int);
+	strncpy((YCHAR *) (xb + pos), name, reclen);
+	pos += (namelen + 1);
+	memcpy(xb + pos, buf, bsize);
+	return 0;
+}
+
+int nval_get(const char *xb, int xb_size, const YCHAR * name, char *buf,
+	     int bsize)
+{
+	int pos = nval_find(xb, xb_size, name, NULL);
+	int size;
+
+	if (pos >= 0 && pos < xb_size) {
+
+		memcpy(&size, xb + pos, sizeof(int));
+		pos += sizeof(int);	/* advance past record length */
+		size -= sizeof(int);
+
+		/* Advance over name string */
+		while (xb[pos] && size > 0 && pos < xb_size) {
+			pos++;
+			size--;
+		}
+		/*Advance over NUL */
+		pos++;
+		size--;
+
+		if (size <= bsize) {
+			memcpy(buf, xb + pos, size);
+			return size;
+		}
+
+	}
+	if (pos >= 0)
+		return -ERANGE;
+	else
+		return -ENODATA;
+}
+
+int nval_list(const char *xb, int xb_size, char *buf, int bsize)
+{
+	int pos = 0;
+	int size;
+	int name_len;
+	int ncopied = 0;
+	int filled = 0;
+
+	memcpy(&size, xb + pos, sizeof(int));
+	while (size > sizeof(int) &&
+		size <= xb_size &&
+		(pos + size) < xb_size &&
+		!filled) {
+		pos += sizeof(int);
+		size -= sizeof(int);
+		name_len = strnlen((YCHAR *) (xb + pos), size);
+		if (ncopied + name_len + 1 < bsize) {
+			memcpy(buf, xb + pos, name_len * sizeof(YCHAR));
+			buf += name_len;
+			*buf = '\0';
+			buf++;
+			if (sizeof(YCHAR) > 1) {
+				*buf = '\0';
+				buf++;
+			}
+			ncopied += (name_len + 1);
+		} else {
+			filled = 1;
+		}
+		pos += size;
+		if (pos < xb_size - sizeof(int))
+			memcpy(&size, xb + pos, sizeof(int));
+		else
+			size = 0;
+	}
+	return ncopied;
+}
+
+int nval_hasvalues(const char *xb, int xb_size)
+{
+	return nval_used(xb, xb_size) > 0;
+}
diff --git a/fs/yaffs2/yaffs_nameval.h b/fs/yaffs2/yaffs_nameval.h
new file mode 100644
index 0000000..2bb02b6
--- /dev/null
+++ b/fs/yaffs2/yaffs_nameval.h
@@ -0,0 +1,28 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __NAMEVAL_H__
+#define __NAMEVAL_H__
+
+#include "yportenv.h"
+
+int nval_del(char *xb, int xb_size, const YCHAR * name);
+int nval_set(char *xb, int xb_size, const YCHAR * name, const char *buf,
+	     int bsize, int flags);
+int nval_get(const char *xb, int xb_size, const YCHAR * name, char *buf,
+	     int bsize);
+int nval_list(const char *xb, int xb_size, char *buf, int bsize);
+int nval_hasvalues(const char *xb, int xb_size);
+#endif
-- 
1.7.1

Re: [PATCH 02/10] Add yaffs2 file system: Attribute and xattrib handling code

[Ryan Mallon]

On 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Couple of comments below.

~Ryan

> ---
>  fs/yaffs2/yaffs_attribs.c |  124 +++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_attribs.h |   28 ++++++
>  fs/yaffs2/yaffs_nameval.c |  204 +++++++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_nameval.h |   28 ++++++
>  4 files changed, 384 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_attribs.c
>  create mode 100644 fs/yaffs2/yaffs_attribs.h
>  create mode 100644 fs/yaffs2/yaffs_nameval.c
>  create mode 100644 fs/yaffs2/yaffs_nameval.h
> 
> diff --git a/fs/yaffs2/yaffs_attribs.c b/fs/yaffs2/yaffs_attribs.c
> new file mode 100644
> index 0000000..9b47d37
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_attribs.c
> @@ -0,0 +1,124 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_guts.h"
> +#include "yaffs_attribs.h"
> +
> +void yaffs_load_attribs(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh)
> +{
> +	obj->yst_uid = oh->yst_uid;
> +	obj->yst_gid = oh->yst_gid;
> +	obj->yst_atime = oh->yst_atime;
> +	obj->yst_mtime = oh->yst_mtime;
> +	obj->yst_ctime = oh->yst_ctime;
> +	obj->yst_rdev = oh->yst_rdev;
> +}
> +
> +void yaffs_load_attribs_oh(struct yaffs_obj_hdr *oh, struct yaffs_obj *obj)
> +{
> +	oh->yst_uid = obj->yst_uid;
> +	oh->yst_gid = obj->yst_gid;
> +	oh->yst_atime = obj->yst_atime;
> +	oh->yst_mtime = obj->yst_mtime;
> +	oh->yst_ctime = obj->yst_ctime;
> +	oh->yst_rdev = obj->yst_rdev;
> +
> +}
> +
> +void yaffs_load_current_time(struct yaffs_obj *obj, int do_a, int do_c)
> +{
> +	obj->yst_mtime = Y_CURRENT_TIME;
> +	if (do_a)
> +		obj->yst_atime = obj->yst_mtime;
> +	if (do_c)
> +		obj->yst_ctime = obj->yst_mtime;
> +}
> +
> +void yaffs_attribs_init(struct yaffs_obj *obj, u32 gid, u32 uid, u32 rdev)
> +{
> +	yaffs_load_current_time(obj, 1, 1);
> +	obj->yst_rdev = rdev;
> +	obj->yst_uid = uid;
> +	obj->yst_gid = gid;
> +}
> +
> +loff_t yaffs_get_file_size(struct yaffs_obj *obj)
> +{
> +	YCHAR *alias = NULL;

You shouldn't need to initialise alias to NULL here.

> +	obj = yaffs_get_equivalent_obj(obj);
> +
> +	switch (obj->variant_type) {
> +	case YAFFS_OBJECT_TYPE_FILE:
> +		return obj->variant.file_variant.file_size;
> +	case YAFFS_OBJECT_TYPE_SYMLINK:
> +		alias = obj->variant.symlink_variant.alias;
> +		if (!alias)
> +			return 0;
> +		return strnlen(alias, YAFFS_MAX_ALIAS_LENGTH);
> +	default:
> +		return 0;
> +	}
> +}
> +
> +int yaffs_set_attribs(struct yaffs_obj *obj, struct iattr *attr)
> +{
> +	unsigned int valid = attr->ia_valid;
> +
> +	if (valid & ATTR_MODE)
> +		obj->yst_mode = attr->ia_mode;
> +	if (valid & ATTR_UID)
> +		obj->yst_uid = attr->ia_uid;
> +	if (valid & ATTR_GID)
> +		obj->yst_gid = attr->ia_gid;
> +
> +	if (valid & ATTR_ATIME)
> +		obj->yst_atime = Y_TIME_CONVERT(attr->ia_atime);
> +	if (valid & ATTR_CTIME)
> +		obj->yst_ctime = Y_TIME_CONVERT(attr->ia_ctime);
> +	if (valid & ATTR_MTIME)
> +		obj->yst_mtime = Y_TIME_CONVERT(attr->ia_mtime);
> +
> +	if (valid & ATTR_SIZE)
> +		yaffs_resize_file(obj, attr->ia_size);
> +
> +	yaffs_update_oh(obj, NULL, 1, 0, 0, NULL);
> +
> +	return YAFFS_OK;
> +
> +}
> +
> +int yaffs_get_attribs(struct yaffs_obj *obj, struct iattr *attr)
> +{
> +	unsigned int valid = 0;
> +
> +	attr->ia_mode = obj->yst_mode;
> +	valid |= ATTR_MODE;
> +	attr->ia_uid = obj->yst_uid;
> +	valid |= ATTR_UID;
> +	attr->ia_gid = obj->yst_gid;
> +	valid |= ATTR_GID;
> +
> +	Y_TIME_CONVERT(attr->ia_atime) = obj->yst_atime;
> +	valid |= ATTR_ATIME;
> +	Y_TIME_CONVERT(attr->ia_ctime) = obj->yst_ctime;
> +	valid |= ATTR_CTIME;
> +	Y_TIME_CONVERT(attr->ia_mtime) = obj->yst_mtime;
> +	valid |= ATTR_MTIME;
> +
> +	attr->ia_size = yaffs_get_file_size(obj);
> +	valid |= ATTR_SIZE;
> +
> +	attr->ia_valid = valid;
> +
> +	return YAFFS_OK;
> +}
> diff --git a/fs/yaffs2/yaffs_attribs.h b/fs/yaffs2/yaffs_attribs.h
> new file mode 100644
> index 0000000..33d541d
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_attribs.h
> @@ -0,0 +1,28 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_ATTRIBS_H__
> +#define __YAFFS_ATTRIBS_H__
> +
> +#include "yaffs_guts.h"
> +
> +void yaffs_load_attribs(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh);
> +void yaffs_load_attribs_oh(struct yaffs_obj_hdr *oh, struct yaffs_obj *obj);
> +void yaffs_attribs_init(struct yaffs_obj *obj, u32 gid, u32 uid, u32 rdev);
> +void yaffs_load_current_time(struct yaffs_obj *obj, int do_a, int do_c);
> +int yaffs_set_attribs(struct yaffs_obj *obj, struct iattr *attr);
> +int yaffs_get_attribs(struct yaffs_obj *obj, struct iattr *attr);
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_nameval.c b/fs/yaffs2/yaffs_nameval.c
> new file mode 100644
> index 0000000..18c30b3
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_nameval.c
> @@ -0,0 +1,204 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +/*
> + * This simple implementation of a name-value store assumes a small number of
> +* values and fits into a small finite buffer.
> + *
> + * Each attribute is stored as a record:
> + *  sizeof(int) bytes   record size.
> + *  strnlen+1 bytes name null terminated.
> + *  nbytes    value.
> + *  ----------
> + *  total size  stored in record size
> + *
> + * This code has not been tested with unicode yet.
> + */
> +
> +#include "yaffs_nameval.h"
> +
> +#include "yportenv.h"
> +
> +static int nval_find(const char *xb, int xb_size, const YCHAR *name,
> +		     int *exist_size)
> +{
> +	int pos = 0;
> +	int size;
> +
> +	memcpy(&size, xb, sizeof(int));
> +	while (size > 0 && (size < xb_size) && (pos + size < xb_size)) {
> +		if (strncmp
> +		    ((YCHAR *) (xb + pos + sizeof(int)), name, size) == 0) {

Maybe more readable as:

	YCHAR *tmp = xb + pos + sizeof(int);

	if (strncmp(tmp, name, size) == 0) {
		...

> +			if (exist_size)
> +				*exist_size = size;
> +			return pos;
> +		}
> +		pos += size;
> +		if (pos < xb_size - sizeof(int))
> +			memcpy(&size, xb + pos, sizeof(int));
> +		else
> +			size = 0;
> +	}
> +	if (exist_size)
> +		*exist_size = 0;
> +	return -1;

Return a proper errno value.

> +}
> +
> +static int nval_used(const char *xb, int xb_size)
> +{
> +	int pos = 0;
> +	int size;
> +
> +	memcpy(&size, xb + pos, sizeof(int));
> +	while (size > 0 && (size < xb_size) && (pos + size < xb_size)) {
> +		pos += size;
> +		if (pos < xb_size - sizeof(int))
> +			memcpy(&size, xb + pos, sizeof(int));
> +		else
> +			size = 0;
> +	}
> +	return pos;
> +}
> +
> +int nval_del(char *xb, int xb_size, const YCHAR *name)
> +{
> +	int pos = nval_find(xb, xb_size, name, NULL);
> +	int size;
> +
> +	if (pos >= 0 && pos < xb_size) {
> +		/* Find size, shift rest over this record,
> +		 * then zero out the rest of buffer */
> +		memcpy(&size, xb + pos, sizeof(int));
> +		memcpy(xb + pos, xb + pos + size, xb_size - (pos + size));
> +		memset(xb + (xb_size - size), 0, size);
> +		return 0;
> +	} else {
> +		return -ENODATA;
> +	}
> +}
> +
> +int nval_set(char *xb, int xb_size, const YCHAR *name, const char *buf,
> +		int bsize, int flags)
> +{
> +	int pos;
> +	int namelen = strnlen(name, xb_size);
> +	int reclen;
> +	int size_exist = 0;
> +	int space;
> +	int start;
> +
> +	pos = nval_find(xb, xb_size, name, &size_exist);
> +
> +	if (flags & XATTR_CREATE && pos >= 0)
> +		return -EEXIST;
> +	if (flags & XATTR_REPLACE && pos < 0)
> +		return -ENODATA;
> +
> +	start = nval_used(xb, xb_size);
> +	space = xb_size - start + size_exist;
> +
> +	reclen = (sizeof(int) + namelen + 1 + bsize);
> +
> +	if (reclen > space)
> +		return -ENOSPC;
> +
> +	if (pos >= 0) {
> +		nval_del(xb, xb_size, name);
> +		start = nval_used(xb, xb_size);
> +	}
> +
> +	pos = start;
> +
> +	memcpy(xb + pos, &reclen, sizeof(int));
> +	pos += sizeof(int);
> +	strncpy((YCHAR *) (xb + pos), name, reclen);
> +	pos += (namelen + 1);
> +	memcpy(xb + pos, buf, bsize);
> +	return 0;
> +}
> +
> +int nval_get(const char *xb, int xb_size, const YCHAR * name, char *buf,
> +	     int bsize)
> +{
> +	int pos = nval_find(xb, xb_size, name, NULL);
> +	int size;
> +
> +	if (pos >= 0 && pos < xb_size) {
> +
> +		memcpy(&size, xb + pos, sizeof(int));
> +		pos += sizeof(int);	/* advance past record length */
> +		size -= sizeof(int);
> +
> +		/* Advance over name string */
> +		while (xb[pos] && size > 0 && pos < xb_size) {
> +			pos++;
> +			size--;
> +		}
> +		/*Advance over NUL */
> +		pos++;
> +		size--;
> +
> +		if (size <= bsize) {
> +			memcpy(buf, xb + pos, size);
> +			return size;
> +		}
> +
> +	}
> +	if (pos >= 0)
> +		return -ERANGE;
> +	else
> +		return -ENODATA;
> +}
> +
> +int nval_list(const char *xb, int xb_size, char *buf, int bsize)
> +{
> +	int pos = 0;
> +	int size;
> +	int name_len;
> +	int ncopied = 0;
> +	int filled = 0;
> +
> +	memcpy(&size, xb + pos, sizeof(int));
> +	while (size > sizeof(int) &&
> +		size <= xb_size &&
> +		(pos + size) < xb_size &&
> +		!filled) {
> +		pos += sizeof(int);
> +		size -= sizeof(int);
> +		name_len = strnlen((YCHAR *) (xb + pos), size);
> +		if (ncopied + name_len + 1 < bsize) {
> +			memcpy(buf, xb + pos, name_len * sizeof(YCHAR));
> +			buf += name_len;
> +			*buf = '\0';
> +			buf++;
> +			if (sizeof(YCHAR) > 1) {
> +				*buf = '\0';
> +				buf++;
> +			}
> +			ncopied += (name_len + 1);
> +		} else {
> +			filled = 1;
> +		}
> +		pos += size;
> +		if (pos < xb_size - sizeof(int))
> +			memcpy(&size, xb + pos, sizeof(int));
> +		else
> +			size = 0;
> +	}
> +	return ncopied;
> +}
> +
> +int nval_hasvalues(const char *xb, int xb_size)
> +{
> +	return nval_used(xb, xb_size) > 0;
> +}
> diff --git a/fs/yaffs2/yaffs_nameval.h b/fs/yaffs2/yaffs_nameval.h
> new file mode 100644
> index 0000000..2bb02b6
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_nameval.h
> @@ -0,0 +1,28 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __NAMEVAL_H__
> +#define __NAMEVAL_H__
> +
> +#include "yportenv.h"
> +
> +int nval_del(char *xb, int xb_size, const YCHAR * name);
> +int nval_set(char *xb, int xb_size, const YCHAR * name, const char *buf,
> +	     int bsize, int flags);
> +int nval_get(const char *xb, int xb_size, const YCHAR * name, char *buf,
> +	     int bsize);
> +int nval_list(const char *xb, int xb_size, char *buf, int bsize);
> +int nval_hasvalues(const char *xb, int xb_size);
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 03/10] Add yaffs2 file system: Checkpoint handing code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_checkptrw.c |  407 +++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_checkptrw.h |   33 ++++
 2 files changed, 440 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_checkptrw.c
 create mode 100644 fs/yaffs2/yaffs_checkptrw.h

diff --git a/fs/yaffs2/yaffs_checkptrw.c b/fs/yaffs2/yaffs_checkptrw.c
new file mode 100644
index 0000000..711df13
--- /dev/null
+++ b/fs/yaffs2/yaffs_checkptrw.c
@@ -0,0 +1,407 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_checkptrw.h"
+#include "yaffs_getblockinfo.h"
+
+static int yaffs2_checkpt_space_ok(struct yaffs_dev *dev)
+{
+	int blocks_avail = dev->n_erased_blocks - dev->param.n_reserved_blocks;
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"checkpt blocks_avail = %d", blocks_avail);
+
+	return (blocks_avail <= 0) ? 0 : 1;
+}
+
+static int yaffs_checkpt_erase(struct yaffs_dev *dev)
+{
+	int i;
+
+	if (!dev->param.erase_fn)
+		return 0;
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"checking blocks %d to %d",
+		dev->internal_start_block, dev->internal_end_block);
+
+	for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
+		struct yaffs_block_info *bi = yaffs_get_block_info(dev, i);
+		if (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT) {
+			yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"erasing checkpt block %d", i);
+
+			dev->n_erasures++;
+
+			if (dev->param.
+			    erase_fn(dev,
+				     i - dev->block_offset /* realign */)) {
+				bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
+				dev->n_erased_blocks++;
+				dev->n_free_chunks +=
+				    dev->param.chunks_per_block;
+			} else {
+				dev->param.bad_block_fn(dev, i);
+				bi->block_state = YAFFS_BLOCK_STATE_DEAD;
+			}
+		}
+	}
+
+	dev->blocks_in_checkpt = 0;
+
+	return 1;
+}
+
+static void yaffs2_checkpt_find_erased_block(struct yaffs_dev *dev)
+{
+	int i;
+	int blocks_avail = dev->n_erased_blocks - dev->param.n_reserved_blocks;
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"allocating checkpt block: erased %d reserved %d avail %d next %d ",
+		dev->n_erased_blocks, dev->param.n_reserved_blocks,
+		blocks_avail, dev->checkpt_next_block);
+
+	if (dev->checkpt_next_block >= 0 &&
+	    dev->checkpt_next_block <= dev->internal_end_block &&
+	    blocks_avail > 0) {
+
+		for (i = dev->checkpt_next_block; i <= dev->internal_end_block;
+		     i++) {
+			struct yaffs_block_info *bi =
+			    yaffs_get_block_info(dev, i);
+			if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
+				dev->checkpt_next_block = i + 1;
+				dev->checkpt_cur_block = i;
+				yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+					"allocating checkpt block %d", i);
+				return;
+			}
+		}
+	}
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT, "out of checkpt blocks");
+
+	dev->checkpt_next_block = -1;
+	dev->checkpt_cur_block = -1;
+}
+
+static void yaffs2_checkpt_find_block(struct yaffs_dev *dev)
+{
+	int i;
+	struct yaffs_ext_tags tags;
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"find next checkpt block: start:  blocks %d next %d",
+		dev->blocks_in_checkpt, dev->checkpt_next_block);
+
+	if (dev->blocks_in_checkpt < dev->checkpt_max_blocks)
+		for (i = dev->checkpt_next_block; i <= dev->internal_end_block;
+		     i++) {
+			int chunk = i * dev->param.chunks_per_block;
+			int realigned_chunk = chunk - dev->chunk_offset;
+
+			dev->param.read_chunk_tags_fn(dev, realigned_chunk,
+						      NULL, &tags);
+			yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+				"find next checkpt block: search: block %d oid %d seq %d eccr %d",
+				i, tags.obj_id, tags.seq_number,
+				tags.ecc_result);
+
+			if (tags.seq_number == YAFFS_SEQUENCE_CHECKPOINT_DATA) {
+				/* Right kind of block */
+				dev->checkpt_next_block = tags.obj_id;
+				dev->checkpt_cur_block = i;
+				dev->checkpt_block_list[dev->
+							blocks_in_checkpt] = i;
+				dev->blocks_in_checkpt++;
+				yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+					"found checkpt block %d", i);
+				return;
+			}
+		}
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT, "found no more checkpt blocks");
+
+	dev->checkpt_next_block = -1;
+	dev->checkpt_cur_block = -1;
+}
+
+int yaffs2_checkpt_open(struct yaffs_dev *dev, int writing)
+{
+	dev->checkpt_open_write = writing;
+
+	/* Got the functions we need? */
+	if (!dev->param.write_chunk_tags_fn ||
+	    !dev->param.read_chunk_tags_fn ||
+	    !dev->param.erase_fn || !dev->param.bad_block_fn)
+		return 0;
+
+	if (writing && !yaffs2_checkpt_space_ok(dev))
+		return 0;
+
+	if (!dev->checkpt_buffer)
+		dev->checkpt_buffer =
+		    kmalloc(dev->param.total_bytes_per_chunk, GFP_NOFS);
+	if (!dev->checkpt_buffer)
+		return 0;
+
+	dev->checkpt_page_seq = 0;
+	dev->checkpt_byte_count = 0;
+	dev->checkpt_sum = 0;
+	dev->checkpt_xor = 0;
+	dev->checkpt_cur_block = -1;
+	dev->checkpt_cur_chunk = -1;
+	dev->checkpt_next_block = dev->internal_start_block;
+
+	/* Erase all the blocks in the checkpoint area */
+	if (writing) {
+		memset(dev->checkpt_buffer, 0, dev->data_bytes_per_chunk);
+		dev->checkpt_byte_offs = 0;
+		return yaffs_checkpt_erase(dev);
+	} else {
+		int i;
+		/* Set to a value that will kick off a read */
+		dev->checkpt_byte_offs = dev->data_bytes_per_chunk;
+		/* A checkpoint block list of 1 checkpoint block per 16 block is
+		 * (hopefully) going to be way more than we need */
+		dev->blocks_in_checkpt = 0;
+		dev->checkpt_max_blocks =
+		    (dev->internal_end_block - dev->internal_start_block) / 16 +
+		    2;
+		dev->checkpt_block_list =
+		    kmalloc(sizeof(int) * dev->checkpt_max_blocks, GFP_NOFS);
+		if (!dev->checkpt_block_list)
+			return 0;
+
+		for (i = 0; i < dev->checkpt_max_blocks; i++)
+			dev->checkpt_block_list[i] = -1;
+	}
+
+	return 1;
+}
+
+int yaffs2_get_checkpt_sum(struct yaffs_dev *dev, u32 * sum)
+{
+	u32 composite_sum;
+
+	composite_sum = (dev->checkpt_sum << 8) | (dev->checkpt_xor & 0xFF);
+	*sum = composite_sum;
+	return 1;
+}
+
+static int yaffs2_checkpt_flush_buffer(struct yaffs_dev *dev)
+{
+	int chunk;
+	int realigned_chunk;
+	struct yaffs_ext_tags tags;
+
+	if (dev->checkpt_cur_block < 0) {
+		yaffs2_checkpt_find_erased_block(dev);
+		dev->checkpt_cur_chunk = 0;
+	}
+
+	if (dev->checkpt_cur_block < 0)
+		return 0;
+
+	tags.is_deleted = 0;
+	tags.obj_id = dev->checkpt_next_block;	/* Hint to next place to look */
+	tags.chunk_id = dev->checkpt_page_seq + 1;
+	tags.seq_number = YAFFS_SEQUENCE_CHECKPOINT_DATA;
+	tags.n_bytes = dev->data_bytes_per_chunk;
+	if (dev->checkpt_cur_chunk == 0) {
+		/* First chunk we write for the block? Set block state to
+		   checkpoint */
+		struct yaffs_block_info *bi =
+		    yaffs_get_block_info(dev, dev->checkpt_cur_block);
+		bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
+		dev->blocks_in_checkpt++;
+	}
+
+	chunk =
+	    dev->checkpt_cur_block * dev->param.chunks_per_block +
+	    dev->checkpt_cur_chunk;
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"checkpoint wite buffer nand %d(%d:%d) objid %d chId %d",
+		chunk, dev->checkpt_cur_block, dev->checkpt_cur_chunk,
+		tags.obj_id, tags.chunk_id);
+
+	realigned_chunk = chunk - dev->chunk_offset;
+
+	dev->n_page_writes++;
+
+	dev->param.write_chunk_tags_fn(dev, realigned_chunk,
+				       dev->checkpt_buffer, &tags);
+	dev->checkpt_byte_offs = 0;
+	dev->checkpt_page_seq++;
+	dev->checkpt_cur_chunk++;
+	if (dev->checkpt_cur_chunk >= dev->param.chunks_per_block) {
+		dev->checkpt_cur_chunk = 0;
+		dev->checkpt_cur_block = -1;
+	}
+	memset(dev->checkpt_buffer, 0, dev->data_bytes_per_chunk);
+
+	return 1;
+}
+
+int yaffs2_checkpt_wr(struct yaffs_dev *dev, const void *data, int n_bytes)
+{
+	int i = 0;
+	int ok = 1;
+	u8 *data_bytes = (u8 *) data;
+
+	if (!dev->checkpt_buffer)
+		return 0;
+
+	if (!dev->checkpt_open_write)
+		return -1;
+
+	while (i < n_bytes && ok) {
+		dev->checkpt_buffer[dev->checkpt_byte_offs] = *data_bytes;
+		dev->checkpt_sum += *data_bytes;
+		dev->checkpt_xor ^= *data_bytes;
+
+		dev->checkpt_byte_offs++;
+		i++;
+		data_bytes++;
+		dev->checkpt_byte_count++;
+
+		if (dev->checkpt_byte_offs < 0 ||
+		    dev->checkpt_byte_offs >= dev->data_bytes_per_chunk)
+			ok = yaffs2_checkpt_flush_buffer(dev);
+	}
+
+	return i;
+}
+
+int yaffs2_checkpt_rd(struct yaffs_dev *dev, void *data, int n_bytes)
+{
+	int i = 0;
+	int ok = 1;
+	struct yaffs_ext_tags tags;
+	int chunk;
+	int realigned_chunk;
+	u8 *data_bytes = (u8 *) data;
+
+	if (!dev->checkpt_buffer)
+		return 0;
+
+	if (dev->checkpt_open_write)
+		return -1;
+
+	while (i < n_bytes && ok) {
+
+		if (dev->checkpt_byte_offs < 0 ||
+		    dev->checkpt_byte_offs >= dev->data_bytes_per_chunk) {
+
+			if (dev->checkpt_cur_block < 0) {
+				yaffs2_checkpt_find_block(dev);
+				dev->checkpt_cur_chunk = 0;
+			}
+
+			if (dev->checkpt_cur_block < 0)
+				ok = 0;
+			else {
+				chunk = dev->checkpt_cur_block *
+				    dev->param.chunks_per_block +
+				    dev->checkpt_cur_chunk;
+
+				realigned_chunk = chunk - dev->chunk_offset;
+
+				dev->n_page_reads++;
+
+				/* read in the next chunk */
+				dev->param.read_chunk_tags_fn(dev,
+							realigned_chunk,
+							dev->checkpt_buffer,
+							&tags);
+
+				if (tags.chunk_id != (dev->checkpt_page_seq + 1)
+				    || tags.ecc_result > YAFFS_ECC_RESULT_FIXED
+				    || tags.seq_number !=
+				    YAFFS_SEQUENCE_CHECKPOINT_DATA)
+					ok = 0;
+
+				dev->checkpt_byte_offs = 0;
+				dev->checkpt_page_seq++;
+				dev->checkpt_cur_chunk++;
+
+				if (dev->checkpt_cur_chunk >=
+				    dev->param.chunks_per_block)
+					dev->checkpt_cur_block = -1;
+			}
+		}
+
+		if (ok) {
+			*data_bytes =
+			    dev->checkpt_buffer[dev->checkpt_byte_offs];
+			dev->checkpt_sum += *data_bytes;
+			dev->checkpt_xor ^= *data_bytes;
+			dev->checkpt_byte_offs++;
+			i++;
+			data_bytes++;
+			dev->checkpt_byte_count++;
+		}
+	}
+
+	return i;
+}
+
+int yaffs_checkpt_close(struct yaffs_dev *dev)
+{
+	if (dev->checkpt_open_write) {
+		if (dev->checkpt_byte_offs != 0)
+			yaffs2_checkpt_flush_buffer(dev);
+	} else if (dev->checkpt_block_list) {
+		int i;
+		for (i = 0;
+		     i < dev->blocks_in_checkpt
+		     && dev->checkpt_block_list[i] >= 0; i++) {
+			int blk = dev->checkpt_block_list[i];
+			struct yaffs_block_info *bi = NULL;
+			if (dev->internal_start_block <= blk
+			    && blk <= dev->internal_end_block)
+				bi = yaffs_get_block_info(dev, blk);
+			if (bi && bi->block_state == YAFFS_BLOCK_STATE_EMPTY)
+				bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
+		}
+		kfree(dev->checkpt_block_list);
+		dev->checkpt_block_list = NULL;
+	}
+
+	dev->n_free_chunks -=
+	    dev->blocks_in_checkpt * dev->param.chunks_per_block;
+	dev->n_erased_blocks -= dev->blocks_in_checkpt;
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT, "checkpoint byte count %d",
+		dev->checkpt_byte_count);
+
+	if (dev->checkpt_buffer) {
+		/* free the buffer */
+		kfree(dev->checkpt_buffer);
+		dev->checkpt_buffer = NULL;
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+int yaffs2_checkpt_invalidate_stream(struct yaffs_dev *dev)
+{
+	/* Erase the checkpoint data */
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"checkpoint invalidate of %d blocks",
+		dev->blocks_in_checkpt);
+
+	return yaffs_checkpt_erase(dev);
+}
diff --git a/fs/yaffs2/yaffs_checkptrw.h b/fs/yaffs2/yaffs_checkptrw.h
new file mode 100644
index 0000000..361c606
--- /dev/null
+++ b/fs/yaffs2/yaffs_checkptrw.h
@@ -0,0 +1,33 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_CHECKPTRW_H__
+#define __YAFFS_CHECKPTRW_H__
+
+#include "yaffs_guts.h"
+
+int yaffs2_checkpt_open(struct yaffs_dev *dev, int writing);
+
+int yaffs2_checkpt_wr(struct yaffs_dev *dev, const void *data, int n_bytes);
+
+int yaffs2_checkpt_rd(struct yaffs_dev *dev, void *data, int n_bytes);
+
+int yaffs2_get_checkpt_sum(struct yaffs_dev *dev, u32 * sum);
+
+int yaffs_checkpt_close(struct yaffs_dev *dev);
+
+int yaffs2_checkpt_invalidate_stream(struct yaffs_dev *dev);
+
+#endif
-- 
1.7.1

Re: [PATCH 03/10] Add yaffs2 file system: Checkpoint handing code

[Ryan Mallon]

On 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Comments below.
~Ryan

> ---
>  fs/yaffs2/yaffs_checkptrw.c |  407 +++++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_checkptrw.h |   33 ++++
>  2 files changed, 440 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_checkptrw.c
>  create mode 100644 fs/yaffs2/yaffs_checkptrw.h
> 
> diff --git a/fs/yaffs2/yaffs_checkptrw.c b/fs/yaffs2/yaffs_checkptrw.c
> new file mode 100644
> index 0000000..711df13
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_checkptrw.c
> @@ -0,0 +1,407 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_checkptrw.h"
> +#include "yaffs_getblockinfo.h"
> +
> +static int yaffs2_checkpt_space_ok(struct yaffs_dev *dev)
> +{
> +	int blocks_avail = dev->n_erased_blocks - dev->param.n_reserved_blocks;
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"checkpt blocks_avail = %d", blocks_avail);
> +
> +	return (blocks_avail <= 0) ? 0 : 1;

return blocks_avail > 0; ?

> +}
> +
> +static int yaffs_checkpt_erase(struct yaffs_dev *dev)
> +{
> +	int i;
> +
> +	if (!dev->param.erase_fn)
> +		return 0;
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"checking blocks %d to %d",
> +		dev->internal_start_block, dev->internal_end_block);
> +
> +	for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
> +		struct yaffs_block_info *bi = yaffs_get_block_info(dev, i);
> +		if (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT) {
> +			yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"erasing checkpt block %d", i);
> +
> +			dev->n_erasures++;
> +
> +			if (dev->param.
> +			    erase_fn(dev,
> +				     i - dev->block_offset /* realign */)) {

Stuff like this gets really hard to read. Try not to split lines on the
. operator. Move the comment to the next at least.

> +				bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
> +				dev->n_erased_blocks++;
> +				dev->n_free_chunks +=
> +				    dev->param.chunks_per_block;
> +			} else {
> +				dev->param.bad_block_fn(dev, i);
> +				bi->block_state = YAFFS_BLOCK_STATE_DEAD;
> +			}
> +		}
> +	}
> +
> +	dev->blocks_in_checkpt = 0;
> +
> +	return 1;
> +}
> +
> +static void yaffs2_checkpt_find_erased_block(struct yaffs_dev *dev)
> +{
> +	int i;
> +	int blocks_avail = dev->n_erased_blocks - dev->param.n_reserved_blocks;
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"allocating checkpt block: erased %d reserved %d avail %d next %d ",
> +		dev->n_erased_blocks, dev->param.n_reserved_blocks,
> +		blocks_avail, dev->checkpt_next_block);
> +
> +	if (dev->checkpt_next_block >= 0 &&
> +	    dev->checkpt_next_block <= dev->internal_end_block &&
> +	    blocks_avail > 0) {
> +
> +		for (i = dev->checkpt_next_block; i <= dev->internal_end_block;
> +		     i++) {
> +			struct yaffs_block_info *bi =
> +			    yaffs_get_block_info(dev, i);
> +			if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
> +				dev->checkpt_next_block = i + 1;
> +				dev->checkpt_cur_block = i;
> +				yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +					"allocating checkpt block %d", i);
> +				return;
> +			}
> +		}
> +	}
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT, "out of checkpt blocks");
> +
> +	dev->checkpt_next_block = -1;
> +	dev->checkpt_cur_block = -1;
> +}
> +
> +static void yaffs2_checkpt_find_block(struct yaffs_dev *dev)
> +{
> +	int i;
> +	struct yaffs_ext_tags tags;
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"find next checkpt block: start:  blocks %d next %d",
> +		dev->blocks_in_checkpt, dev->checkpt_next_block);
> +
> +	if (dev->blocks_in_checkpt < dev->checkpt_max_blocks)
> +		for (i = dev->checkpt_next_block; i <= dev->internal_end_block;
> +		     i++) {
> +			int chunk = i * dev->param.chunks_per_block;
> +			int realigned_chunk = chunk - dev->chunk_offset;
> +
> +			dev->param.read_chunk_tags_fn(dev, realigned_chunk,
> +						      NULL, &tags);
> +			yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +				"find next checkpt block: search: block %d oid %d seq %d eccr %d",
> +				i, tags.obj_id, tags.seq_number,
> +				tags.ecc_result);
> +
> +			if (tags.seq_number == YAFFS_SEQUENCE_CHECKPOINT_DATA) {
> +				/* Right kind of block */
> +				dev->checkpt_next_block = tags.obj_id;
> +				dev->checkpt_cur_block = i;
> +				dev->checkpt_block_list[dev->
> +							blocks_in_checkpt] = i;

Lines like this can probably just go on one line. It will only just
break the 80 columns 'limit' and it makes it a bit more readable.

> +				dev->blocks_in_checkpt++;
> +				yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +					"found checkpt block %d", i);
> +				return;
> +			}
> +		}
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT, "found no more checkpt blocks");
> +
> +	dev->checkpt_next_block = -1;
> +	dev->checkpt_cur_block = -1;
> +}
> +
> +int yaffs2_checkpt_open(struct yaffs_dev *dev, int writing)
> +{
> +	dev->checkpt_open_write = writing;
> +
> +	/* Got the functions we need? */
> +	if (!dev->param.write_chunk_tags_fn ||
> +	    !dev->param.read_chunk_tags_fn ||
> +	    !dev->param.erase_fn || !dev->param.bad_block_fn)
> +		return 0;
> +
> +	if (writing && !yaffs2_checkpt_space_ok(dev))
> +		return 0;
> +
> +	if (!dev->checkpt_buffer)
> +		dev->checkpt_buffer =
> +		    kmalloc(dev->param.total_bytes_per_chunk, GFP_NOFS);
> +	if (!dev->checkpt_buffer)
> +		return 0;

Possibly this function should return 0 on success and a negative errno
value on error?

> +	dev->checkpt_page_seq = 0;
> +	dev->checkpt_byte_count = 0;
> +	dev->checkpt_sum = 0;
> +	dev->checkpt_xor = 0;
> +	dev->checkpt_cur_block = -1;
> +	dev->checkpt_cur_chunk = -1;
> +	dev->checkpt_next_block = dev->internal_start_block;
> +
> +	/* Erase all the blocks in the checkpoint area */
> +	if (writing) {
> +		memset(dev->checkpt_buffer, 0, dev->data_bytes_per_chunk);
> +		dev->checkpt_byte_offs = 0;
> +		return yaffs_checkpt_erase(dev);
> +	} else {
> +		int i;
> +		/* Set to a value that will kick off a read */
> +		dev->checkpt_byte_offs = dev->data_bytes_per_chunk;
> +		/* A checkpoint block list of 1 checkpoint block per 16 block is
> +		 * (hopefully) going to be way more than we need */
> +		dev->blocks_in_checkpt = 0;
> +		dev->checkpt_max_blocks =
> +		    (dev->internal_end_block - dev->internal_start_block) / 16 +
> +		    2;
> +		dev->checkpt_block_list =
> +		    kmalloc(sizeof(int) * dev->checkpt_max_blocks, GFP_NOFS);
> +		if (!dev->checkpt_block_list)
> +			return 0;
> +
> +		for (i = 0; i < dev->checkpt_max_blocks; i++)
> +			dev->checkpt_block_list[i] = -1;
> +	}
> +
> +	return 1;
> +}
> +
> +int yaffs2_get_checkpt_sum(struct yaffs_dev *dev, u32 * sum)
> +{
> +	u32 composite_sum;
> +
> +	composite_sum = (dev->checkpt_sum << 8) | (dev->checkpt_xor & 0xFF);
> +	*sum = composite_sum;

You don't need the composite_sum temporary, just assign directly to
*sum. The return type of this function can probably be changed to void also.

> +	return 1;
> +}
> +
> +static int yaffs2_checkpt_flush_buffer(struct yaffs_dev *dev)
> +{
> +	int chunk;
> +	int realigned_chunk;
> +	struct yaffs_ext_tags tags;
> +
> +	if (dev->checkpt_cur_block < 0) {
> +		yaffs2_checkpt_find_erased_block(dev);
> +		dev->checkpt_cur_chunk = 0;
> +	}
> +
> +	if (dev->checkpt_cur_block < 0)
> +		return 0;
> +
> +	tags.is_deleted = 0;
> +	tags.obj_id = dev->checkpt_next_block;	/* Hint to next place to look */
> +	tags.chunk_id = dev->checkpt_page_seq + 1;
> +	tags.seq_number = YAFFS_SEQUENCE_CHECKPOINT_DATA;
> +	tags.n_bytes = dev->data_bytes_per_chunk;
> +	if (dev->checkpt_cur_chunk == 0) {
> +		/* First chunk we write for the block? Set block state to
> +		   checkpoint */
> +		struct yaffs_block_info *bi =
> +		    yaffs_get_block_info(dev, dev->checkpt_cur_block);
> +		bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
> +		dev->blocks_in_checkpt++;
> +	}
> +
> +	chunk =
> +	    dev->checkpt_cur_block * dev->param.chunks_per_block +
> +	    dev->checkpt_cur_chunk;
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"checkpoint wite buffer nand %d(%d:%d) objid %d chId %d",
> +		chunk, dev->checkpt_cur_block, dev->checkpt_cur_chunk,
> +		tags.obj_id, tags.chunk_id);
> +
> +	realigned_chunk = chunk - dev->chunk_offset;
> +
> +	dev->n_page_writes++;
> +
> +	dev->param.write_chunk_tags_fn(dev, realigned_chunk,
> +				       dev->checkpt_buffer, &tags);
> +	dev->checkpt_byte_offs = 0;
> +	dev->checkpt_page_seq++;
> +	dev->checkpt_cur_chunk++;
> +	if (dev->checkpt_cur_chunk >= dev->param.chunks_per_block) {
> +		dev->checkpt_cur_chunk = 0;
> +		dev->checkpt_cur_block = -1;
> +	}
> +	memset(dev->checkpt_buffer, 0, dev->data_bytes_per_chunk);
> +
> +	return 1;
> +}
> +
> +int yaffs2_checkpt_wr(struct yaffs_dev *dev, const void *data, int n_bytes)
> +{
> +	int i = 0;
> +	int ok = 1;
> +	u8 *data_bytes = (u8 *) data;
> +
> +	if (!dev->checkpt_buffer)
> +		return 0;
> +
> +	if (!dev->checkpt_open_write)
> +		return -1;

errno value?

> +
> +	while (i < n_bytes && ok) {
> +		dev->checkpt_buffer[dev->checkpt_byte_offs] = *data_bytes;
> +		dev->checkpt_sum += *data_bytes;
> +		dev->checkpt_xor ^= *data_bytes;
> +
> +		dev->checkpt_byte_offs++;
> +		i++;
> +		data_bytes++;
> +		dev->checkpt_byte_count++;
> +
> +		if (dev->checkpt_byte_offs < 0 ||
> +		    dev->checkpt_byte_offs >= dev->data_bytes_per_chunk)
> +			ok = yaffs2_checkpt_flush_buffer(dev);
> +	}
> +
> +	return i;
> +}
> +
> +int yaffs2_checkpt_rd(struct yaffs_dev *dev, void *data, int n_bytes)
> +{
> +	int i = 0;
> +	int ok = 1;
> +	struct yaffs_ext_tags tags;
> +	int chunk;
> +	int realigned_chunk;
> +	u8 *data_bytes = (u8 *) data;

Shouldn't need the cast here.

> +
> +	if (!dev->checkpt_buffer)
> +		return 0;
> +
> +	if (dev->checkpt_open_write)
> +		return -1;

errno value?

> +
> +	while (i < n_bytes && ok) {
> +
> +		if (dev->checkpt_byte_offs < 0 ||
> +		    dev->checkpt_byte_offs >= dev->data_bytes_per_chunk) {
> +
> +			if (dev->checkpt_cur_block < 0) {
> +				yaffs2_checkpt_find_block(dev);
> +				dev->checkpt_cur_chunk = 0;
> +			}
> +
> +			if (dev->checkpt_cur_block < 0)
> +				ok = 0;

The if should have braces here. If either the if or the else has braces,
then both should.

> +			else {

Possibly worth moving the body of this else to a separate function to
reduce indentation craziness.

> +				chunk = dev->checkpt_cur_block *
> +				    dev->param.chunks_per_block +
> +				    dev->checkpt_cur_chunk;
> +
> +				realigned_chunk = chunk - dev->chunk_offset;
> +
> +				dev->n_page_reads++;
> +
> +				/* read in the next chunk */
> +				dev->param.read_chunk_tags_fn(dev,
> +							realigned_chunk,
> +							dev->checkpt_buffer,
> +							&tags);
> +
> +				if (tags.chunk_id != (dev->checkpt_page_seq + 1)
> +				    || tags.ecc_result > YAFFS_ECC_RESULT_FIXED
> +				    || tags.seq_number !=

There is a mix of putting && and || at the end and the beginning of
lines in this file. Pick one and be consistent. I think that end of line
is generally preferred.

> +				    YAFFS_SEQUENCE_CHECKPOINT_DATA)
> +					ok = 0;
> +
> +				dev->checkpt_byte_offs = 0;
> +				dev->checkpt_page_seq++;
> +				dev->checkpt_cur_chunk++;
> +
> +				if (dev->checkpt_cur_chunk >=
> +				    dev->param.chunks_per_block)
> +					dev->checkpt_cur_block = -1;
> +			}
> +		}
> +
> +		if (ok) {
> +			*data_bytes =
> +			    dev->checkpt_buffer[dev->checkpt_byte_offs];
> +			dev->checkpt_sum += *data_bytes;
> +			dev->checkpt_xor ^= *data_bytes;
> +			dev->checkpt_byte_offs++;
> +			i++;
> +			data_bytes++;
> +			dev->checkpt_byte_count++;
> +		}
> +	}
> +
> +	return i;
> +}
> +
> +int yaffs_checkpt_close(struct yaffs_dev *dev)
> +{
> +	if (dev->checkpt_open_write) {
> +		if (dev->checkpt_byte_offs != 0)
> +			yaffs2_checkpt_flush_buffer(dev);
> +	} else if (dev->checkpt_block_list) {
> +		int i;
> +		for (i = 0;
> +		     i < dev->blocks_in_checkpt
> +		     && dev->checkpt_block_list[i] >= 0; i++) {
> +			int blk = dev->checkpt_block_list[i];
> +			struct yaffs_block_info *bi = NULL;

Blank line between variable declarations and code.

> +			if (dev->internal_start_block <= blk
> +			    && blk <= dev->internal_end_block)
> +				bi = yaffs_get_block_info(dev, blk);
> +			if (bi && bi->block_state == YAFFS_BLOCK_STATE_EMPTY)
> +				bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
> +		}
> +		kfree(dev->checkpt_block_list);
> +		dev->checkpt_block_list = NULL;
> +	}
> +
> +	dev->n_free_chunks -=
> +	    dev->blocks_in_checkpt * dev->param.chunks_per_block;
> +	dev->n_erased_blocks -= dev->blocks_in_checkpt;
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT, "checkpoint byte count %d",
> +		dev->checkpt_byte_count);
> +
> +	if (dev->checkpt_buffer) {
> +		/* free the buffer */

Pointless comment :-).

> +		kfree(dev->checkpt_buffer);
> +		dev->checkpt_buffer = NULL;
> +		return 1;
> +	} else {
> +		return 0;
> +	}

You don't really need the else, just put return 0 at the end of the
function.

> +}
> +
> +int yaffs2_checkpt_invalidate_stream(struct yaffs_dev *dev)
> +{
> +	/* Erase the checkpoint data */
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"checkpoint invalidate of %d blocks",
> +		dev->blocks_in_checkpt);
> +
> +	return yaffs_checkpt_erase(dev);
> +}
> diff --git a/fs/yaffs2/yaffs_checkptrw.h b/fs/yaffs2/yaffs_checkptrw.h
> new file mode 100644
> index 0000000..361c606
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_checkptrw.h
> @@ -0,0 +1,33 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_CHECKPTRW_H__
> +#define __YAFFS_CHECKPTRW_H__
> +
> +#include "yaffs_guts.h"
> +
> +int yaffs2_checkpt_open(struct yaffs_dev *dev, int writing);
> +
> +int yaffs2_checkpt_wr(struct yaffs_dev *dev, const void *data, int n_bytes);
> +
> +int yaffs2_checkpt_rd(struct yaffs_dev *dev, void *data, int n_bytes);
> +
> +int yaffs2_get_checkpt_sum(struct yaffs_dev *dev, u32 * sum);
> +
> +int yaffs_checkpt_close(struct yaffs_dev *dev);
> +
> +int yaffs2_checkpt_invalidate_stream(struct yaffs_dev *dev);
> +
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 04/10] Add yaffs2 file system: Flash interfacing and ECC handling code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_ecc.c    |  296 +++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_ecc.h    |   44 ++++++
 fs/yaffs2/yaffs_mtdif.c  |   53 ++++++++
 fs/yaffs2/yaffs_mtdif.h  |   23 ++++
 fs/yaffs2/yaffs_mtdif1.c |  329 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_mtdif1.h |   29 ++++
 fs/yaffs2/yaffs_mtdif2.c |  215 ++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_mtdif2.h |   29 ++++
 fs/yaffs2/yaffs_nand.c   |  120 +++++++++++++++++
 fs/yaffs2/yaffs_nand.h   |   38 ++++++
 10 files changed, 1176 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_ecc.c
 create mode 100644 fs/yaffs2/yaffs_ecc.h
 create mode 100644 fs/yaffs2/yaffs_mtdif.c
 create mode 100644 fs/yaffs2/yaffs_mtdif.h
 create mode 100644 fs/yaffs2/yaffs_mtdif1.c
 create mode 100644 fs/yaffs2/yaffs_mtdif1.h
 create mode 100644 fs/yaffs2/yaffs_mtdif2.c
 create mode 100644 fs/yaffs2/yaffs_mtdif2.h
 create mode 100644 fs/yaffs2/yaffs_nand.c
 create mode 100644 fs/yaffs2/yaffs_nand.h

diff --git a/fs/yaffs2/yaffs_ecc.c b/fs/yaffs2/yaffs_ecc.c
new file mode 100644
index 0000000..4f29b80
--- /dev/null
+++ b/fs/yaffs2/yaffs_ecc.c
@@ -0,0 +1,296 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * This code implements the ECC algorithm used in SmartMedia.
+ *
+ * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
+ * The two unused bit are set to 1.
+ * The ECC can correct single bit errors in a 256-byte page of data. Thus, two
+ * such ECC blocks are used on a 512-byte NAND page.
+ *
+ */
+
+/* Table generated by gen-ecc.c
+ * Using a table means we do not have to calculate p1..p4 and p1'..p4'
+ * for each byte of data. These are instead provided in a table in bits7..2.
+ * Bit 0 of each entry indicates whether the entry has an odd or even parity,
+ * and therefore this bytes influence on the line parity.
+ */
+
+#include "yportenv.h"
+
+#include "yaffs_ecc.h"
+
+static const unsigned char column_parity_table[] = {
+	0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
+	0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
+	0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
+	0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
+	0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
+	0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
+	0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
+	0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
+	0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
+	0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
+	0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
+	0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
+	0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
+	0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
+	0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
+	0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
+	0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
+	0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
+	0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
+	0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
+	0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
+	0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
+	0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
+	0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
+	0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
+	0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
+	0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
+	0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
+	0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
+	0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
+	0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
+	0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
+};
+
+
+/* Calculate the ECC for a 256-byte block of data */
+void yaffs_ecc_cacl(const unsigned char *data, unsigned char *ecc)
+{
+	unsigned int i;
+	unsigned char col_parity = 0;
+	unsigned char line_parity = 0;
+	unsigned char line_parity_prime = 0;
+	unsigned char t;
+	unsigned char b;
+
+	for (i = 0; i < 256; i++) {
+		b = column_parity_table[*data++];
+		col_parity ^= b;
+
+		if (b & 0x01) {	/* odd number of bits in the byte */
+			line_parity ^= i;
+			line_parity_prime ^= ~i;
+		}
+	}
+
+	ecc[2] = (~col_parity) | 0x03;
+
+	t = 0;
+	if (line_parity & 0x80)
+		t |= 0x80;
+	if (line_parity_prime & 0x80)
+		t |= 0x40;
+	if (line_parity & 0x40)
+		t |= 0x20;
+	if (line_parity_prime & 0x40)
+		t |= 0x10;
+	if (line_parity & 0x20)
+		t |= 0x08;
+	if (line_parity_prime & 0x20)
+		t |= 0x04;
+	if (line_parity & 0x10)
+		t |= 0x02;
+	if (line_parity_prime & 0x10)
+		t |= 0x01;
+	ecc[1] = ~t;
+
+	t = 0;
+	if (line_parity & 0x08)
+		t |= 0x80;
+	if (line_parity_prime & 0x08)
+		t |= 0x40;
+	if (line_parity & 0x04)
+		t |= 0x20;
+	if (line_parity_prime & 0x04)
+		t |= 0x10;
+	if (line_parity & 0x02)
+		t |= 0x08;
+	if (line_parity_prime & 0x02)
+		t |= 0x04;
+	if (line_parity & 0x01)
+		t |= 0x02;
+	if (line_parity_prime & 0x01)
+		t |= 0x01;
+	ecc[0] = ~t;
+
+#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
+	/* Swap the bytes into the wrong order */
+	t = ecc[0];
+	ecc[0] = ecc[1];
+	ecc[1] = t;
+#endif
+}
+
+/* Correct the ECC on a 256 byte block of data */
+
+int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
+		      const unsigned char *test_ecc)
+{
+	unsigned char d0, d1, d2;	/* deltas */
+
+	d0 = read_ecc[0] ^ test_ecc[0];
+	d1 = read_ecc[1] ^ test_ecc[1];
+	d2 = read_ecc[2] ^ test_ecc[2];
+
+	if ((d0 | d1 | d2) == 0)
+		return 0;	/* no error */
+
+	if (((d0 ^ (d0 >> 1)) & 0x55) == 0x55 &&
+	    ((d1 ^ (d1 >> 1)) & 0x55) == 0x55 &&
+	    ((d2 ^ (d2 >> 1)) & 0x54) == 0x54) {
+		/* Single bit (recoverable) error in data */
+
+		unsigned byte;
+		unsigned bit;
+
+#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
+		/* swap the bytes to correct for the wrong order */
+		unsigned char t;
+
+		t = d0;
+		d0 = d1;
+		d1 = t;
+#endif
+
+		bit = byte = 0;
+
+		if (d1 & 0x80)
+			byte |= 0x80;
+		if (d1 & 0x20)
+			byte |= 0x40;
+		if (d1 & 0x08)
+			byte |= 0x20;
+		if (d1 & 0x02)
+			byte |= 0x10;
+		if (d0 & 0x80)
+			byte |= 0x08;
+		if (d0 & 0x20)
+			byte |= 0x04;
+		if (d0 & 0x08)
+			byte |= 0x02;
+		if (d0 & 0x02)
+			byte |= 0x01;
+
+		if (d2 & 0x80)
+			bit |= 0x04;
+		if (d2 & 0x20)
+			bit |= 0x02;
+		if (d2 & 0x08)
+			bit |= 0x01;
+
+		data[byte] ^= (1 << bit);
+
+		return 1;	/* Corrected the error */
+	}
+
+	if ((hweight8(d0) + hweight8(d1) + hweight8(d2)) == 1) {
+		/* Reccoverable error in ecc */
+
+		read_ecc[0] = test_ecc[0];
+		read_ecc[1] = test_ecc[1];
+		read_ecc[2] = test_ecc[2];
+
+		return 1;	/* Corrected the error */
+	}
+
+	/* Unrecoverable error */
+
+	return -1;
+
+}
+
+/*
+ * ECCxxxOther does ECC calcs on arbitrary n bytes of data
+ */
+void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes,
+			  struct yaffs_ecc_other *ecc_other)
+{
+	unsigned int i;
+	unsigned char col_parity = 0;
+	unsigned line_parity = 0;
+	unsigned line_parity_prime = 0;
+	unsigned char b;
+
+	for (i = 0; i < n_bytes; i++) {
+		b = column_parity_table[*data++];
+		col_parity ^= b;
+
+		if (b & 0x01) {
+			/* odd number of bits in the byte */
+			line_parity ^= i;
+			line_parity_prime ^= ~i;
+		}
+
+	}
+
+	ecc_other->col_parity = (col_parity >> 2) & 0x3f;
+	ecc_other->line_parity = line_parity;
+	ecc_other->line_parity_prime = line_parity_prime;
+}
+
+int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes,
+			    struct yaffs_ecc_other *read_ecc,
+			    const struct yaffs_ecc_other *test_ecc)
+{
+	unsigned char delta_col;	/* column parity delta */
+	unsigned delta_line;	/* line parity delta */
+	unsigned delta_line_prime;	/* line parity delta */
+	unsigned bit;
+
+	delta_col = read_ecc->col_parity ^ test_ecc->col_parity;
+	delta_line = read_ecc->line_parity ^ test_ecc->line_parity;
+	delta_line_prime =
+	    read_ecc->line_parity_prime ^ test_ecc->line_parity_prime;
+
+	if ((delta_col | delta_line | delta_line_prime) == 0)
+		return 0;	/* no error */
+
+	if (delta_line == ~delta_line_prime &&
+	    (((delta_col ^ (delta_col >> 1)) & 0x15) == 0x15)) {
+		/* Single bit (recoverable) error in data */
+
+		bit = 0;
+
+		if (delta_col & 0x20)
+			bit |= 0x04;
+		if (delta_col & 0x08)
+			bit |= 0x02;
+		if (delta_col & 0x02)
+			bit |= 0x01;
+
+		if (delta_line >= n_bytes)
+			return -1;
+
+		data[delta_line] ^= (1 << bit);
+
+		return 1;	/* corrected */
+	}
+
+	if ((hweight32(delta_line) +
+	     hweight32(delta_line_prime) +
+	     hweight8(delta_col)) == 1) {
+		/* Reccoverable error in ecc */
+
+		*read_ecc = *test_ecc;
+		return 1;	/* corrected */
+	}
+
+	/* Unrecoverable error */
+
+	return -1;
+}
diff --git a/fs/yaffs2/yaffs_ecc.h b/fs/yaffs2/yaffs_ecc.h
new file mode 100644
index 0000000..a84e801
--- /dev/null
+++ b/fs/yaffs2/yaffs_ecc.h
@@ -0,0 +1,44 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+/*
+ * This code implements the ECC algorithm used in SmartMedia.
+ *
+ * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
+ * The two unused bit are set to 1.
+ * The ECC can correct single bit errors in a 256-byte page of data.
+ * Thus, two such ECC blocks are used on a 512-byte NAND page.
+ *
+ */
+
+#ifndef __YAFFS_ECC_H__
+#define __YAFFS_ECC_H__
+
+struct yaffs_ecc_other {
+	unsigned char col_parity;
+	unsigned line_parity;
+	unsigned line_parity_prime;
+};
+
+void yaffs_ecc_cacl(const unsigned char *data, unsigned char *ecc);
+int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
+		      const unsigned char *test_ecc);
+
+void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes,
+			  struct yaffs_ecc_other *ecc);
+int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes,
+			    struct yaffs_ecc_other *read_ecc,
+			    const struct yaffs_ecc_other *test_ecc);
+#endif
diff --git a/fs/yaffs2/yaffs_mtdif.c b/fs/yaffs2/yaffs_mtdif.c
new file mode 100644
index 0000000..b36a8be
--- /dev/null
+++ b/fs/yaffs2/yaffs_mtdif.c
@@ -0,0 +1,53 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yportenv.h"
+
+#include "yaffs_mtdif.h"
+
+#include "linux/mtd/mtd.h"
+#include "linux/types.h"
+#include "linux/time.h"
+#include "linux/mtd/nand.h"
+
+#include "yaffs_linux.h"
+
+int nandmtd_erase_block(struct yaffs_dev *dev, int block_no)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	u32 addr =
+	    ((loff_t) block_no) * dev->param.total_bytes_per_chunk
+	    * dev->param.chunks_per_block;
+	struct erase_info ei;
+	int retval = 0;
+
+	ei.mtd = mtd;
+	ei.addr = addr;
+	ei.len = dev->param.total_bytes_per_chunk * dev->param.chunks_per_block;
+	ei.time = 1000;
+	ei.retries = 2;
+	ei.callback = NULL;
+	ei.priv = (u_long) dev;
+
+	retval = mtd->erase(mtd, &ei);
+
+	if (retval == 0)
+		return YAFFS_OK;
+	else
+		return YAFFS_FAIL;
+}
+
+int nandmtd_initialise(struct yaffs_dev *dev)
+{
+	return YAFFS_OK;
+}
diff --git a/fs/yaffs2/yaffs_mtdif.h b/fs/yaffs2/yaffs_mtdif.h
new file mode 100644
index 0000000..6665074
--- /dev/null
+++ b/fs/yaffs2/yaffs_mtdif.h
@@ -0,0 +1,23 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_MTDIF_H__
+#define __YAFFS_MTDIF_H__
+
+#include "yaffs_guts.h"
+
+int nandmtd_erase_block(struct yaffs_dev *dev, int block_no);
+int nandmtd_initialise(struct yaffs_dev *dev);
+#endif
diff --git a/fs/yaffs2/yaffs_mtdif1.c b/fs/yaffs2/yaffs_mtdif1.c
new file mode 100644
index 0000000..182870c
--- /dev/null
+++ b/fs/yaffs2/yaffs_mtdif1.c
@@ -0,0 +1,329 @@
+/*
+ * YAFFS: Yet another FFS. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * This module provides the interface between yaffs_nand.c and the
+ * MTD API.  This version is used when the MTD interface supports the
+ * 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
+ * and we have small-page NAND device.
+ *
+ * These functions are invoked via function pointers in yaffs_nand.c.
+ * This replaces functionality provided by functions in yaffs_mtdif.c
+ * and the yaffs_tags compatability functions in yaffs_tagscompat.c that are
+ * called in yaffs_mtdif.c when the function pointers are NULL.
+ * We assume the MTD layer is performing ECC (use_nand_ecc is true).
+ */
+
+#include "yportenv.h"
+#include "yaffs_trace.h"
+#include "yaffs_guts.h"
+#include "yaffs_packedtags1.h"
+#include "yaffs_tagscompat.h"	/* for yaffs_calc_tags_ecc */
+#include "yaffs_linux.h"
+#include "linux/kernel.h"
+#include "linux/version.h"
+#include "linux/types.h"
+#include "linux/mtd/mtd.h"
+
+#ifndef CONFIG_YAFFS_9BYTE_TAGS
+# define YTAG1_SIZE 8
+#else
+# define YTAG1_SIZE 9
+#endif
+
+/* Write a chunk (page) of data to NAND.
+ *
+ * Caller always provides ExtendedTags data which are converted to a more
+ * compact (packed) form for storage in NAND.  A mini-ECC runs over the
+ * contents of the tags meta-data; used to valid the tags when read.
+ *
+ *  - Pack ExtendedTags to packed_tags1 form
+ *  - Compute mini-ECC for packed_tags1
+ *  - Write data and packed tags to NAND.
+ *
+ * Note: Due to the use of the packed_tags1 meta-data which does not include
+ * a full sequence number (as found in the larger packed_tags2 form) it is
+ * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
+ * discarded and dirty.  This is not ideal: newer NAND parts are supposed
+ * to be written just once.  When Yaffs performs this operation, this
+ * function is called with a NULL data pointer -- calling MTD write_oob
+ * without data is valid usage (2.6.17).
+ *
+ * Any underlying MTD error results in YAFFS_FAIL.
+ * Returns YAFFS_OK or YAFFS_FAIL.
+ */
+int nandmtd1_write_chunk_tags(struct yaffs_dev *dev,
+			      int nand_chunk, const u8 *data,
+			      const struct yaffs_ext_tags *etags)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	int chunk_bytes = dev->data_bytes_per_chunk;
+	loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
+	struct mtd_oob_ops ops;
+	struct yaffs_packed_tags1 pt1;
+	int retval;
+
+	/* we assume that packed_tags1 and struct yaffs_tags are compatible */
+	compile_time_assertion(sizeof(struct yaffs_packed_tags1) == 12);
+	compile_time_assertion(sizeof(struct yaffs_tags) == 8);
+
+	yaffs_pack_tags1(&pt1, etags);
+	yaffs_calc_tags_ecc((struct yaffs_tags *)&pt1);
+
+	/* When deleting a chunk, the upper layer provides only skeletal
+	 * etags, one with is_deleted set.  However, we need to update the
+	 * tags, not erase them completely.  So we use the NAND write property
+	 * that only zeroed-bits stick and set tag bytes to all-ones and
+	 * zero just the (not) deleted bit.
+	 */
+#ifndef CONFIG_YAFFS_9BYTE_TAGS
+	if (etags->is_deleted) {
+		memset(&pt1, 0xff, 8);
+		/* clear delete status bit to indicate deleted */
+		pt1.deleted = 0;
+	}
+#else
+	((u8 *) &pt1)[8] = 0xff;
+	if (etags->is_deleted) {
+		memset(&pt1, 0xff, 8);
+		/* zero page_status byte to indicate deleted */
+		((u8 *) &pt1)[8] = 0;
+	}
+#endif
+
+	memset(&ops, 0, sizeof(ops));
+	ops.mode = MTD_OOB_AUTO;
+	ops.len = (data) ? chunk_bytes : 0;
+	ops.ooblen = YTAG1_SIZE;
+	ops.datbuf = (u8 *) data;
+	ops.oobbuf = (u8 *) &pt1;
+
+	retval = mtd->write_oob(mtd, addr, &ops);
+	if (retval) {
+		yaffs_trace(YAFFS_TRACE_MTD,
+			"write_oob failed, chunk %d, mtd error %d",
+			nand_chunk, retval);
+	}
+	return retval ? YAFFS_FAIL : YAFFS_OK;
+}
+
+/* Return with empty ExtendedTags but add ecc_result.
+ */
+static int rettags(struct yaffs_ext_tags *etags, int ecc_result, int retval)
+{
+	if (etags) {
+		memset(etags, 0, sizeof(*etags));
+		etags->ecc_result = ecc_result;
+	}
+	return retval;
+}
+
+/* Read a chunk (page) from NAND.
+ *
+ * Caller expects ExtendedTags data to be usable even on error; that is,
+ * all members except ecc_result and block_bad are zeroed.
+ *
+ *  - Check ECC results for data (if applicable)
+ *  - Check for blank/erased block (return empty ExtendedTags if blank)
+ *  - Check the packed_tags1 mini-ECC (correct if necessary/possible)
+ *  - Convert packed_tags1 to ExtendedTags
+ *  - Update ecc_result and block_bad members to refect state.
+ *
+ * Returns YAFFS_OK or YAFFS_FAIL.
+ */
+int nandmtd1_read_chunk_tags(struct yaffs_dev *dev,
+			     int nand_chunk, u8 *data,
+			     struct yaffs_ext_tags *etags)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	int chunk_bytes = dev->data_bytes_per_chunk;
+	loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
+	int eccres = YAFFS_ECC_RESULT_NO_ERROR;
+	struct mtd_oob_ops ops;
+	struct yaffs_packed_tags1 pt1;
+	int retval;
+	int deleted;
+
+	memset(&ops, 0, sizeof(ops));
+	ops.mode = MTD_OOB_AUTO;
+	ops.len = (data) ? chunk_bytes : 0;
+	ops.ooblen = YTAG1_SIZE;
+	ops.datbuf = data;
+	ops.oobbuf = (u8 *) &pt1;
+
+	/* Read page and oob using MTD.
+	 * Check status and determine ECC result.
+	 */
+	retval = mtd->read_oob(mtd, addr, &ops);
+	if (retval) {
+		yaffs_trace(YAFFS_TRACE_MTD,
+			"read_oob failed, chunk %d, mtd error %d",
+			nand_chunk, retval);
+	}
+
+	switch (retval) {
+	case 0:
+		/* no error */
+		break;
+
+	case -EUCLEAN:
+		/* MTD's ECC fixed the data */
+		eccres = YAFFS_ECC_RESULT_FIXED;
+		dev->n_ecc_fixed++;
+		break;
+
+	case -EBADMSG:
+		/* MTD's ECC could not fix the data */
+		dev->n_ecc_unfixed++;
+		/* fall into... */
+	default:
+		rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
+		etags->block_bad = (mtd->block_isbad) (mtd, addr);
+		return YAFFS_FAIL;
+	}
+
+	/* Check for a blank/erased chunk.
+	 */
+	if (yaffs_check_ff((u8 *) &pt1, 8)) {
+		/* when blank, upper layers want ecc_result to be <= NO_ERROR */
+		return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
+	}
+#ifndef CONFIG_YAFFS_9BYTE_TAGS
+	/* Read deleted status (bit) then return it to it's non-deleted
+	 * state before performing tags mini-ECC check. pt1.deleted is
+	 * inverted.
+	 */
+	deleted = !pt1.deleted;
+	pt1.deleted = 1;
+#else
+	deleted = (hweight8(((u8 *) &pt1)[8]) < 7);
+#endif
+
+	/* Check the packed tags mini-ECC and correct if necessary/possible.
+	 */
+	retval = yaffs_check_tags_ecc((struct yaffs_tags *)&pt1);
+	switch (retval) {
+	case 0:
+		/* no tags error, use MTD result */
+		break;
+	case 1:
+		/* recovered tags-ECC error */
+		dev->n_tags_ecc_fixed++;
+		if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
+			eccres = YAFFS_ECC_RESULT_FIXED;
+		break;
+	default:
+		/* unrecovered tags-ECC error */
+		dev->n_tags_ecc_unfixed++;
+		return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
+	}
+
+	/* Unpack the tags to extended form and set ECC result.
+	 * [set should_be_ff just to keep yaffs_unpack_tags1 happy]
+	 */
+	pt1.should_be_ff = 0xFFFFFFFF;
+	yaffs_unpack_tags1(etags, &pt1);
+	etags->ecc_result = eccres;
+
+	/* Set deleted state */
+	etags->is_deleted = deleted;
+	return YAFFS_OK;
+}
+
+/* Mark a block bad.
+ *
+ * This is a persistant state.
+ * Use of this function should be rare.
+ *
+ * Returns YAFFS_OK or YAFFS_FAIL.
+ */
+int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
+	int retval;
+
+	yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
+		"marking block %d bad", block_no);
+
+	retval = mtd->block_markbad(mtd, (loff_t) blocksize * block_no);
+	return (retval) ? YAFFS_FAIL : YAFFS_OK;
+}
+
+/* Check any MTD prerequists.
+ *
+ * Returns YAFFS_OK or YAFFS_FAIL.
+ */
+static int nandmtd1_test_prerequists(struct mtd_info *mtd)
+{
+	/* 2.6.18 has mtd->ecclayout->oobavail */
+	/* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
+	int oobavail = mtd->ecclayout->oobavail;
+
+	if (oobavail < YTAG1_SIZE) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"mtd device has only %d bytes for tags, need %d",
+			oobavail, YTAG1_SIZE);
+		return YAFFS_FAIL;
+	}
+	return YAFFS_OK;
+}
+
+/* Query for the current state of a specific block.
+ *
+ * Examine the tags of the first chunk of the block and return the state:
+ *  - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
+ *  - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
+ *  - YAFFS_BLOCK_STATE_EMPTY, the block is clean
+ *
+ * Always returns YAFFS_OK.
+ */
+int nandmtd1_query_block(struct yaffs_dev *dev, int block_no,
+			 enum yaffs_block_state *state_ptr, u32 * seq_ptr)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	int chunk_num = block_no * dev->param.chunks_per_block;
+	loff_t addr = (loff_t) chunk_num * dev->data_bytes_per_chunk;
+	struct yaffs_ext_tags etags;
+	int state = YAFFS_BLOCK_STATE_DEAD;
+	int seqnum = 0;
+	int retval;
+
+	/* We don't yet have a good place to test for MTD config prerequists.
+	 * Do it here as we are called during the initial scan.
+	 */
+	if (nandmtd1_test_prerequists(mtd) != YAFFS_OK)
+		return YAFFS_FAIL;
+
+	retval = nandmtd1_read_chunk_tags(dev, chunk_num, NULL, &etags);
+	etags.block_bad = (mtd->block_isbad) (mtd, addr);
+	if (etags.block_bad) {
+		yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
+			"block %d is marked bad", block_no);
+		state = YAFFS_BLOCK_STATE_DEAD;
+	} else if (etags.ecc_result != YAFFS_ECC_RESULT_NO_ERROR) {
+		/* bad tags, need to look more closely */
+		state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
+	} else if (etags.chunk_used) {
+		state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
+		seqnum = etags.seq_number;
+	} else {
+		state = YAFFS_BLOCK_STATE_EMPTY;
+	}
+
+	*state_ptr = state;
+	*seq_ptr = seqnum;
+
+	/* query always succeeds */
+	return YAFFS_OK;
+}
diff --git a/fs/yaffs2/yaffs_mtdif1.h b/fs/yaffs2/yaffs_mtdif1.h
new file mode 100644
index 0000000..034c680
--- /dev/null
+++ b/fs/yaffs2/yaffs_mtdif1.h
@@ -0,0 +1,29 @@
+/*
+ * YAFFS: Yet another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_MTDIF1_H__
+#define __YAFFS_MTDIF1_H__
+
+int nandmtd1_write_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
+			      const u8 *data,
+			      const struct yaffs_ext_tags *tags);
+
+int nandmtd1_read_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
+			     u8 *data, struct yaffs_ext_tags *tags);
+
+int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no);
+
+int nandmtd1_query_block(struct yaffs_dev *dev, int block_no,
+			 enum yaffs_block_state *state, u32 *seq_number);
+
+#endif
diff --git a/fs/yaffs2/yaffs_mtdif2.c b/fs/yaffs2/yaffs_mtdif2.c
new file mode 100644
index 0000000..18340bd
--- /dev/null
+++ b/fs/yaffs2/yaffs_mtdif2.c
@@ -0,0 +1,215 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/* mtd interface for YAFFS2 */
+
+#include "yportenv.h"
+#include "yaffs_trace.h"
+#include "yaffs_mtdif2.h"
+#include "yaffs_packedtags2.h"
+#include "yaffs_linux.h"
+#include "linux/mtd/mtd.h"
+#include "linux/types.h"
+#include "linux/time.h"
+
+
+/* NB For use with inband tags....
+ * We assume that the data buffer is of size total_bytes_per_chunk so that
+ * we can also use it to load the tags.
+ */
+int nandmtd2_write_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
+			      const u8 *data,
+			      const struct yaffs_ext_tags *tags)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	struct mtd_oob_ops ops;
+	int retval = 0;
+	loff_t addr;
+	struct yaffs_packed_tags2 pt;
+	int packed_tags_size =
+	    dev->param.no_tags_ecc ? sizeof(pt.t) : sizeof(pt);
+	void *packed_tags_ptr =
+	    dev->param.no_tags_ecc ? (void *)&pt.t : (void *)&pt;
+
+	yaffs_trace(YAFFS_TRACE_MTD,
+		"nandmtd2_write_chunk_tags chunk %d data %p tags %p",
+		nand_chunk, data, tags);
+
+	addr = ((loff_t) nand_chunk) * dev->param.total_bytes_per_chunk;
+
+	/* For yaffs2 writing there must be both data and tags.
+	 * If we're using inband tags, then the tags are stuffed into
+	 * the end of the data buffer.
+	 */
+	if (!data || !tags)
+		BUG();
+	else if (dev->param.inband_tags) {
+		struct yaffs_packed_tags2_tags_only *pt2tp;
+
+		pt2tp =
+		    (struct yaffs_packed_tags2_tags_only *)(data +
+							dev->
+							data_bytes_per_chunk);
+		yaffs_pack_tags2_tags_only(pt2tp, tags);
+	} else {
+		yaffs_pack_tags2(&pt, tags, !dev->param.no_tags_ecc);
+	}
+
+	ops.mode = MTD_OOB_AUTO;
+	ops.ooblen = (dev->param.inband_tags) ? 0 : packed_tags_size;
+	ops.len = dev->param.total_bytes_per_chunk;
+	ops.ooboffs = 0;
+	ops.datbuf = (u8 *) data;
+	ops.oobbuf = (dev->param.inband_tags) ? NULL : packed_tags_ptr;
+	retval = mtd->write_oob(mtd, addr, &ops);
+
+	if (retval == 0)
+		return YAFFS_OK;
+	else
+		return YAFFS_FAIL;
+}
+
+int nandmtd2_read_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
+			     u8 *data, struct yaffs_ext_tags *tags)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	struct mtd_oob_ops ops;
+	size_t dummy;
+	int retval = 0;
+	int local_data = 0;
+	loff_t addr = ((loff_t) nand_chunk) * dev->param.total_bytes_per_chunk;
+	struct yaffs_packed_tags2 pt;
+	int packed_tags_size =
+	    dev->param.no_tags_ecc ? sizeof(pt.t) : sizeof(pt);
+	void *packed_tags_ptr =
+	    dev->param.no_tags_ecc ? (void *)&pt.t : (void *)&pt;
+
+	yaffs_trace(YAFFS_TRACE_MTD,
+		"nandmtd2_read_chunk_tags chunk %d data %p tags %p",
+		nand_chunk, data, tags);
+
+	if (dev->param.inband_tags) {
+
+		if (!data) {
+			local_data = 1;
+			data = yaffs_get_temp_buffer(dev, __LINE__);
+		}
+	}
+
+	if (dev->param.inband_tags || (data && !tags))
+		retval = mtd->read(mtd, addr, dev->param.total_bytes_per_chunk,
+				   &dummy, data);
+	else if (tags) {
+		ops.mode = MTD_OOB_AUTO;
+		ops.ooblen = packed_tags_size;
+		ops.len = data ? dev->data_bytes_per_chunk : packed_tags_size;
+		ops.ooboffs = 0;
+		ops.datbuf = data;
+		ops.oobbuf = yaffs_dev_to_lc(dev)->spare_buffer;
+		retval = mtd->read_oob(mtd, addr, &ops);
+	}
+
+	if (dev->param.inband_tags) {
+		if (tags) {
+			struct yaffs_packed_tags2_tags_only *pt2tp;
+			pt2tp =
+				(struct yaffs_packed_tags2_tags_only *)
+					&data[dev->data_bytes_per_chunk];
+			yaffs_unpack_tags2_tags_only(tags, pt2tp);
+		}
+	} else {
+		if (tags) {
+			memcpy(packed_tags_ptr,
+			       yaffs_dev_to_lc(dev)->spare_buffer,
+			       packed_tags_size);
+			yaffs_unpack_tags2(tags, &pt, !dev->param.no_tags_ecc);
+		}
+	}
+
+	if (local_data)
+		yaffs_release_temp_buffer(dev, data, __LINE__);
+
+	if (tags && retval == -EBADMSG
+	    && tags->ecc_result == YAFFS_ECC_RESULT_NO_ERROR) {
+		tags->ecc_result = YAFFS_ECC_RESULT_UNFIXED;
+		dev->n_ecc_unfixed++;
+	}
+	if (tags && retval == -EUCLEAN
+	    && tags->ecc_result == YAFFS_ECC_RESULT_NO_ERROR) {
+		tags->ecc_result = YAFFS_ECC_RESULT_FIXED;
+		dev->n_ecc_fixed++;
+	}
+	if (retval == 0)
+		return YAFFS_OK;
+	else
+		return YAFFS_FAIL;
+}
+
+int nandmtd2_mark_block_bad(struct yaffs_dev *dev, int block_no)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	int retval;
+
+	yaffs_trace(YAFFS_TRACE_MTD,
+		"nandmtd2_mark_block_bad %d", block_no);
+
+	retval =
+	    mtd->block_markbad(mtd,
+			       block_no * dev->param.chunks_per_block *
+			       dev->param.total_bytes_per_chunk);
+
+	if (retval == 0)
+		return YAFFS_OK;
+	else
+		return YAFFS_FAIL;
+}
+
+int nandmtd2_query_block(struct yaffs_dev *dev, int block_no,
+			 enum yaffs_block_state *state, u32 * seq_number)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
+	int retval;
+
+	yaffs_trace(YAFFS_TRACE_MTD, "nandmtd2_query_block %d", block_no);
+	retval =
+	    mtd->block_isbad(mtd,
+			     block_no * dev->param.chunks_per_block *
+			     dev->param.total_bytes_per_chunk);
+
+	if (retval) {
+		yaffs_trace(YAFFS_TRACE_MTD, "block is bad");
+
+		*state = YAFFS_BLOCK_STATE_DEAD;
+		*seq_number = 0;
+	} else {
+		struct yaffs_ext_tags t;
+		nandmtd2_read_chunk_tags(dev, block_no *
+					 dev->param.chunks_per_block, NULL, &t);
+
+		if (t.chunk_used) {
+			*seq_number = t.seq_number;
+			*state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
+		} else {
+			*seq_number = 0;
+			*state = YAFFS_BLOCK_STATE_EMPTY;
+		}
+	}
+	yaffs_trace(YAFFS_TRACE_MTD,
+		"block is bad seq %d state %d", *seq_number, *state);
+
+	if (retval == 0)
+		return YAFFS_OK;
+	else
+		return YAFFS_FAIL;
+}
+
diff --git a/fs/yaffs2/yaffs_mtdif2.h b/fs/yaffs2/yaffs_mtdif2.h
new file mode 100644
index 0000000..78babf5
--- /dev/null
+++ b/fs/yaffs2/yaffs_mtdif2.h
@@ -0,0 +1,29 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_MTDIF2_H__
+#define __YAFFS_MTDIF2_H__
+
+#include "yaffs_guts.h"
+int nandmtd2_write_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
+			      const u8 *data,
+			      const struct yaffs_ext_tags *tags);
+int nandmtd2_read_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
+			     u8 *data, struct yaffs_ext_tags *tags);
+int nandmtd2_mark_block_bad(struct yaffs_dev *dev, int block_no);
+int nandmtd2_query_block(struct yaffs_dev *dev, int block_no,
+			 enum yaffs_block_state *state, u32 *seq_number);
+
+#endif
diff --git a/fs/yaffs2/yaffs_nand.c b/fs/yaffs2/yaffs_nand.c
new file mode 100644
index 0000000..ee061a8
--- /dev/null
+++ b/fs/yaffs2/yaffs_nand.c
@@ -0,0 +1,120 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_nand.h"
+#include "yaffs_tagscompat.h"
+#include "yaffs_tagsvalidity.h"
+
+#include "yaffs_getblockinfo.h"
+
+int yaffs_rd_chunk_tags_nand(struct yaffs_dev *dev, int nand_chunk,
+			     u8 *buffer, struct yaffs_ext_tags *tags)
+{
+	int result;
+	struct yaffs_ext_tags local_tags;
+	int realigned_chunk = nand_chunk - dev->chunk_offset;
+
+	dev->n_page_reads++;
+
+	/* If there are no tags provided use local tags. */
+	if (!tags)
+		tags = &local_tags;
+
+	if (dev->param.read_chunk_tags_fn)
+		result =
+		    dev->param.read_chunk_tags_fn(dev, realigned_chunk, buffer,
+						  tags);
+	else
+		result = yaffs_tags_compat_rd(dev,
+					      realigned_chunk, buffer, tags);
+	if (tags && tags->ecc_result > YAFFS_ECC_RESULT_NO_ERROR) {
+
+		struct yaffs_block_info *bi;
+		bi = yaffs_get_block_info(dev,
+					  nand_chunk /
+					  dev->param.chunks_per_block);
+		yaffs_handle_chunk_error(dev, bi);
+	}
+	return result;
+}
+
+int yaffs_wr_chunk_tags_nand(struct yaffs_dev *dev,
+				int nand_chunk,
+				const u8 *buffer, struct yaffs_ext_tags *tags)
+{
+	dev->n_page_writes++;
+	nand_chunk -= dev->chunk_offset;
+
+	if (tags) {
+		tags->seq_number = dev->seq_number;
+		tags->chunk_used = 1;
+		if (!yaffs_validate_tags(tags)) {
+			yaffs_trace(YAFFS_TRACE_ERROR,
+				"Writing uninitialised tags");
+			YBUG();
+		}
+		yaffs_trace(YAFFS_TRACE_WRITE,
+			"Writing chunk %d tags %d %d",
+			nand_chunk, tags->obj_id, tags->chunk_id);
+	} else {
+		yaffs_trace(YAFFS_TRACE_ERROR, "Writing with no tags");
+		YBUG();
+		return YAFFS_FAIL;
+	}
+
+	if (dev->param.write_chunk_tags_fn)
+		return dev->param.write_chunk_tags_fn(dev, nand_chunk, buffer,
+							tags);
+	else
+		return yaffs_tags_compat_wr(dev, nand_chunk, buffer, tags);
+}
+
+int yaffs_mark_bad(struct yaffs_dev *dev, int block_no)
+{
+	block_no -= dev->block_offset;
+	if (dev->param.bad_block_fn)
+		return dev->param.bad_block_fn(dev, block_no);
+	else
+		return yaffs_tags_compat_mark_bad(dev, block_no);
+}
+
+int yaffs_query_init_block_state(struct yaffs_dev *dev,
+				 int block_no,
+				 enum yaffs_block_state *state,
+				 u32 *seq_number)
+{
+	block_no -= dev->block_offset;
+	if (dev->param.query_block_fn)
+		return dev->param.query_block_fn(dev, block_no, state,
+						 seq_number);
+	else
+		return yaffs_tags_compat_query_block(dev, block_no,
+						     state, seq_number);
+}
+
+int yaffs_erase_block(struct yaffs_dev *dev, int flash_block)
+{
+	int result;
+
+	flash_block -= dev->block_offset;
+	dev->n_erasures++;
+	result = dev->param.erase_fn(dev, flash_block);
+	return result;
+}
+
+int yaffs_init_nand(struct yaffs_dev *dev)
+{
+	if (dev->param.initialise_flash_fn)
+		return dev->param.initialise_flash_fn(dev);
+	return YAFFS_OK;
+}
diff --git a/fs/yaffs2/yaffs_nand.h b/fs/yaffs2/yaffs_nand.h
new file mode 100644
index 0000000..a36498a
--- /dev/null
+++ b/fs/yaffs2/yaffs_nand.h
@@ -0,0 +1,38 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_NAND_H__
+#define __YAFFS_NAND_H__
+#include "yaffs_guts.h"
+
+int yaffs_rd_chunk_tags_nand(struct yaffs_dev *dev, int nand_chunk,
+			     u8 *buffer, struct yaffs_ext_tags *tags);
+
+int yaffs_wr_chunk_tags_nand(struct yaffs_dev *dev,
+			     int nand_chunk,
+			     const u8 *buffer, struct yaffs_ext_tags *tags);
+
+int yaffs_mark_bad(struct yaffs_dev *dev, int block_no);
+
+int yaffs_query_init_block_state(struct yaffs_dev *dev,
+				 int block_no,
+				 enum yaffs_block_state *state,
+				 unsigned *seq_number);
+
+int yaffs_erase_block(struct yaffs_dev *dev, int flash_block);
+
+int yaffs_init_nand(struct yaffs_dev *dev);
+
+#endif
-- 
1.7.1

Re: [PATCH 04/10] Add yaffs2 file system: Flash interfacing and ECC handling code

[Ryan Mallon]

cOn 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Hi Charles,

Is it possible to make features like yaffs doing its own ecc, ecc wrong
order and 9 byte tags mount options? It would reduce the number of
Kconfig options and the amount of ifdefery in these files.

More comments below.

~Ryan

> ---
>  fs/yaffs2/yaffs_ecc.c    |  296 +++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_ecc.h    |   44 ++++++
>  fs/yaffs2/yaffs_mtdif.c  |   53 ++++++++
>  fs/yaffs2/yaffs_mtdif.h  |   23 ++++
>  fs/yaffs2/yaffs_mtdif1.c |  329 ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_mtdif1.h |   29 ++++
>  fs/yaffs2/yaffs_mtdif2.c |  215 ++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_mtdif2.h |   29 ++++
>  fs/yaffs2/yaffs_nand.c   |  120 +++++++++++++++++
>  fs/yaffs2/yaffs_nand.h   |   38 ++++++
>  10 files changed, 1176 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_ecc.c
>  create mode 100644 fs/yaffs2/yaffs_ecc.h
>  create mode 100644 fs/yaffs2/yaffs_mtdif.c
>  create mode 100644 fs/yaffs2/yaffs_mtdif.h
>  create mode 100644 fs/yaffs2/yaffs_mtdif1.c
>  create mode 100644 fs/yaffs2/yaffs_mtdif1.h
>  create mode 100644 fs/yaffs2/yaffs_mtdif2.c
>  create mode 100644 fs/yaffs2/yaffs_mtdif2.h
>  create mode 100644 fs/yaffs2/yaffs_nand.c
>  create mode 100644 fs/yaffs2/yaffs_nand.h
> 
> diff --git a/fs/yaffs2/yaffs_ecc.c b/fs/yaffs2/yaffs_ecc.c
> new file mode 100644
> index 0000000..4f29b80
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_ecc.c
> @@ -0,0 +1,296 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +/*
> + * This code implements the ECC algorithm used in SmartMedia.
> + *
> + * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
> + * The two unused bit are set to 1.
> + * The ECC can correct single bit errors in a 256-byte page of data. Thus, two
> + * such ECC blocks are used on a 512-byte NAND page.
> + *
> + */
> +
> +/* Table generated by gen-ecc.c
> + * Using a table means we do not have to calculate p1..p4 and p1'..p4'
> + * for each byte of data. These are instead provided in a table in bits7..2.
> + * Bit 0 of each entry indicates whether the entry has an odd or even parity,
> + * and therefore this bytes influence on the line parity.
> + */
> +
> +#include "yportenv.h"
> +
> +#include "yaffs_ecc.h"
> +
> +static const unsigned char column_parity_table[] = {
> +	0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
> +	0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
> +	0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
> +	0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
> +	0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
> +	0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
> +	0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
> +	0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
> +	0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
> +	0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
> +	0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
> +	0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
> +	0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
> +	0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
> +	0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
> +	0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
> +	0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
> +	0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
> +	0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
> +	0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
> +	0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
> +	0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
> +	0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
> +	0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
> +	0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
> +	0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
> +	0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
> +	0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
> +	0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
> +	0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
> +	0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
> +	0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
> +};
> +
> +
> +/* Calculate the ECC for a 256-byte block of data */
> +void yaffs_ecc_cacl(const unsigned char *data, unsigned char *ecc)
> +{
> +	unsigned int i;
> +	unsigned char col_parity = 0;
> +	unsigned char line_parity = 0;
> +	unsigned char line_parity_prime = 0;
> +	unsigned char t;
> +	unsigned char b;
> +
> +	for (i = 0; i < 256; i++) {
> +		b = column_parity_table[*data++];
> +		col_parity ^= b;
> +
> +		if (b & 0x01) {	/* odd number of bits in the byte */
> +			line_parity ^= i;
> +			line_parity_prime ^= ~i;
> +		}
> +	}
> +
> +	ecc[2] = (~col_parity) | 0x03;
> +
> +	t = 0;
> +	if (line_parity & 0x80)
> +		t |= 0x80;
> +	if (line_parity_prime & 0x80)
> +		t |= 0x40;
> +	if (line_parity & 0x40)
> +		t |= 0x20;
> +	if (line_parity_prime & 0x40)
> +		t |= 0x10;
> +	if (line_parity & 0x20)
> +		t |= 0x08;
> +	if (line_parity_prime & 0x20)
> +		t |= 0x04;
> +	if (line_parity & 0x10)
> +		t |= 0x02;
> +	if (line_parity_prime & 0x10)
> +		t |= 0x01;
> +	ecc[1] = ~t;
> +
> +	t = 0;
> +	if (line_parity & 0x08)
> +		t |= 0x80;
> +	if (line_parity_prime & 0x08)
> +		t |= 0x40;
> +	if (line_parity & 0x04)
> +		t |= 0x20;
> +	if (line_parity_prime & 0x04)
> +		t |= 0x10;
> +	if (line_parity & 0x02)
> +		t |= 0x08;
> +	if (line_parity_prime & 0x02)
> +		t |= 0x04;
> +	if (line_parity & 0x01)
> +		t |= 0x02;
> +	if (line_parity_prime & 0x01)
> +		t |= 0x01;
> +	ecc[0] = ~t;
> +
> +#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
> +	/* Swap the bytes into the wrong order */
> +	t = ecc[0];
> +	ecc[0] = ecc[1];
> +	ecc[1] = t;
> +#endif
> +}
> +
> +/* Correct the ECC on a 256 byte block of data */
> +
> +int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
> +		      const unsigned char *test_ecc)
> +{
> +	unsigned char d0, d1, d2;	/* deltas */
> +
> +	d0 = read_ecc[0] ^ test_ecc[0];
> +	d1 = read_ecc[1] ^ test_ecc[1];
> +	d2 = read_ecc[2] ^ test_ecc[2];
> +
> +	if ((d0 | d1 | d2) == 0)
> +		return 0;	/* no error */
> +
> +	if (((d0 ^ (d0 >> 1)) & 0x55) == 0x55 &&
> +	    ((d1 ^ (d1 >> 1)) & 0x55) == 0x55 &&
> +	    ((d2 ^ (d2 >> 1)) & 0x54) == 0x54) {
> +		/* Single bit (recoverable) error in data */
> +
> +		unsigned byte;
> +		unsigned bit;
> +
> +#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
> +		/* swap the bytes to correct for the wrong order */
> +		unsigned char t;
> +
> +		t = d0;
> +		d0 = d1;
> +		d1 = t;
> +#endif
> +
> +		bit = byte = 0;
> +
> +		if (d1 & 0x80)
> +			byte |= 0x80;
> +		if (d1 & 0x20)
> +			byte |= 0x40;
> +		if (d1 & 0x08)
> +			byte |= 0x20;
> +		if (d1 & 0x02)
> +			byte |= 0x10;
> +		if (d0 & 0x80)
> +			byte |= 0x08;
> +		if (d0 & 0x20)
> +			byte |= 0x04;
> +		if (d0 & 0x08)
> +			byte |= 0x02;
> +		if (d0 & 0x02)
> +			byte |= 0x01;
> +
> +		if (d2 & 0x80)
> +			bit |= 0x04;
> +		if (d2 & 0x20)
> +			bit |= 0x02;
> +		if (d2 & 0x08)
> +			bit |= 0x01;
> +
> +		data[byte] ^= (1 << bit);
> +
> +		return 1;	/* Corrected the error */
> +	}
> +
> +	if ((hweight8(d0) + hweight8(d1) + hweight8(d2)) == 1) {
> +		/* Reccoverable error in ecc */
> +
> +		read_ecc[0] = test_ecc[0];
> +		read_ecc[1] = test_ecc[1];
> +		read_ecc[2] = test_ecc[2];
> +
> +		return 1;	/* Corrected the error */
> +	}
> +
> +	/* Unrecoverable error */
> +
> +	return -1;

errno value?

> +}
> +
> +/*
> + * ECCxxxOther does ECC calcs on arbitrary n bytes of data
> + */
> +void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes,
> +			  struct yaffs_ecc_other *ecc_other)
> +{
> +	unsigned int i;
> +	unsigned char col_parity = 0;
> +	unsigned line_parity = 0;
> +	unsigned line_parity_prime = 0;
> +	unsigned char b;
> +
> +	for (i = 0; i < n_bytes; i++) {
> +		b = column_parity_table[*data++];
> +		col_parity ^= b;
> +
> +		if (b & 0x01) {
> +			/* odd number of bits in the byte */
> +			line_parity ^= i;
> +			line_parity_prime ^= ~i;
> +		}
> +
> +	}
> +
> +	ecc_other->col_parity = (col_parity >> 2) & 0x3f;
> +	ecc_other->line_parity = line_parity;
> +	ecc_other->line_parity_prime = line_parity_prime;
> +}
> +
> +int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes,
> +			    struct yaffs_ecc_other *read_ecc,
> +			    const struct yaffs_ecc_other *test_ecc)
> +{
> +	unsigned char delta_col;	/* column parity delta */
> +	unsigned delta_line;	/* line parity delta */
> +	unsigned delta_line_prime;	/* line parity delta */
> +	unsigned bit;
> +
> +	delta_col = read_ecc->col_parity ^ test_ecc->col_parity;
> +	delta_line = read_ecc->line_parity ^ test_ecc->line_parity;
> +	delta_line_prime =
> +	    read_ecc->line_parity_prime ^ test_ecc->line_parity_prime;
> +
> +	if ((delta_col | delta_line | delta_line_prime) == 0)
> +		return 0;	/* no error */
> +
> +	if (delta_line == ~delta_line_prime &&
> +	    (((delta_col ^ (delta_col >> 1)) & 0x15) == 0x15)) {
> +		/* Single bit (recoverable) error in data */
> +
> +		bit = 0;
> +
> +		if (delta_col & 0x20)
> +			bit |= 0x04;
> +		if (delta_col & 0x08)
> +			bit |= 0x02;
> +		if (delta_col & 0x02)
> +			bit |= 0x01;
> +
> +		if (delta_line >= n_bytes)
> +			return -1;
> +
> +		data[delta_line] ^= (1 << bit);
> +
> +		return 1;	/* corrected */
> +	}
> +
> +	if ((hweight32(delta_line) +
> +	     hweight32(delta_line_prime) +
> +	     hweight8(delta_col)) == 1) {
> +		/* Reccoverable error in ecc */
> +
> +		*read_ecc = *test_ecc;
> +		return 1;	/* corrected */
> +	}
> +
> +	/* Unrecoverable error */
> +
> +	return -1;

errno value?

> +}
> diff --git a/fs/yaffs2/yaffs_ecc.h b/fs/yaffs2/yaffs_ecc.h
> new file mode 100644
> index 0000000..a84e801
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_ecc.h
> @@ -0,0 +1,44 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +/*
> + * This code implements the ECC algorithm used in SmartMedia.
> + *
> + * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
> + * The two unused bit are set to 1.
> + * The ECC can correct single bit errors in a 256-byte page of data.
> + * Thus, two such ECC blocks are used on a 512-byte NAND page.
> + *
> + */
> +
> +#ifndef __YAFFS_ECC_H__
> +#define __YAFFS_ECC_H__
> +
> +struct yaffs_ecc_other {
> +	unsigned char col_parity;
> +	unsigned line_parity;
> +	unsigned line_parity_prime;
> +};
> +
> +void yaffs_ecc_cacl(const unsigned char *data, unsigned char *ecc);
> +int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
> +		      const unsigned char *test_ecc);
> +
> +void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes,
> +			  struct yaffs_ecc_other *ecc);
> +int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes,
> +			    struct yaffs_ecc_other *read_ecc,
> +			    const struct yaffs_ecc_other *test_ecc);
> +#endif
> diff --git a/fs/yaffs2/yaffs_mtdif.c b/fs/yaffs2/yaffs_mtdif.c
> new file mode 100644
> index 0000000..b36a8be
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_mtdif.c
> @@ -0,0 +1,53 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yportenv.h"
> +
> +#include "yaffs_mtdif.h"
> +
> +#include "linux/mtd/mtd.h"
> +#include "linux/types.h"
> +#include "linux/time.h"
> +#include "linux/mtd/nand.h"
> +
> +#include "yaffs_linux.h"
> +
> +int nandmtd_erase_block(struct yaffs_dev *dev, int block_no)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	u32 addr =
> +	    ((loff_t) block_no) * dev->param.total_bytes_per_chunk
> +	    * dev->param.chunks_per_block;
> +	struct erase_info ei;
> +	int retval = 0;
> +
> +	ei.mtd = mtd;
> +	ei.addr = addr;
> +	ei.len = dev->param.total_bytes_per_chunk * dev->param.chunks_per_block;
> +	ei.time = 1000;
> +	ei.retries = 2;
> +	ei.callback = NULL;
> +	ei.priv = (u_long) dev;

Nitpick: Casts should be written like this:

	ei.prov = (u_long)dev;

This applies across the whole patch series.

> +
> +	retval = mtd->erase(mtd, &ei);
> +
> +	if (retval == 0)
> +		return YAFFS_OK;
> +	else
> +		return YAFFS_FAIL;
> +}
> +
> +int nandmtd_initialise(struct yaffs_dev *dev)
> +{
> +	return YAFFS_OK;
> +}
> diff --git a/fs/yaffs2/yaffs_mtdif.h b/fs/yaffs2/yaffs_mtdif.h
> new file mode 100644
> index 0000000..6665074
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_mtdif.h
> @@ -0,0 +1,23 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_MTDIF_H__
> +#define __YAFFS_MTDIF_H__
> +
> +#include "yaffs_guts.h"
> +
> +int nandmtd_erase_block(struct yaffs_dev *dev, int block_no);
> +int nandmtd_initialise(struct yaffs_dev *dev);
> +#endif
> diff --git a/fs/yaffs2/yaffs_mtdif1.c b/fs/yaffs2/yaffs_mtdif1.c
> new file mode 100644
> index 0000000..182870c
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_mtdif1.c
> @@ -0,0 +1,329 @@
> +/*
> + * YAFFS: Yet another FFS. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +/*
> + * This module provides the interface between yaffs_nand.c and the
> + * MTD API.  This version is used when the MTD interface supports the
> + * 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
> + * and we have small-page NAND device.
> + *
> + * These functions are invoked via function pointers in yaffs_nand.c.
> + * This replaces functionality provided by functions in yaffs_mtdif.c
> + * and the yaffs_tags compatability functions in yaffs_tagscompat.c that are
> + * called in yaffs_mtdif.c when the function pointers are NULL.
> + * We assume the MTD layer is performing ECC (use_nand_ecc is true).
> + */
> +
> +#include "yportenv.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_guts.h"
> +#include "yaffs_packedtags1.h"
> +#include "yaffs_tagscompat.h"	/* for yaffs_calc_tags_ecc */
> +#include "yaffs_linux.h"
> +#include "linux/kernel.h"
> +#include "linux/version.h"
> +#include "linux/types.h"
> +#include "linux/mtd/mtd.h"
> +
> +#ifndef CONFIG_YAFFS_9BYTE_TAGS
> +# define YTAG1_SIZE 8
> +#else
> +# define YTAG1_SIZE 9
> +#endif
> +
> +/* Write a chunk (page) of data to NAND.
> + *
> + * Caller always provides ExtendedTags data which are converted to a more
> + * compact (packed) form for storage in NAND.  A mini-ECC runs over the
> + * contents of the tags meta-data; used to valid the tags when read.
> + *
> + *  - Pack ExtendedTags to packed_tags1 form
> + *  - Compute mini-ECC for packed_tags1
> + *  - Write data and packed tags to NAND.
> + *
> + * Note: Due to the use of the packed_tags1 meta-data which does not include
> + * a full sequence number (as found in the larger packed_tags2 form) it is
> + * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
> + * discarded and dirty.  This is not ideal: newer NAND parts are supposed
> + * to be written just once.  When Yaffs performs this operation, this
> + * function is called with a NULL data pointer -- calling MTD write_oob
> + * without data is valid usage (2.6.17).
> + *
> + * Any underlying MTD error results in YAFFS_FAIL.
> + * Returns YAFFS_OK or YAFFS_FAIL.
> + */
> +int nandmtd1_write_chunk_tags(struct yaffs_dev *dev,
> +			      int nand_chunk, const u8 *data,
> +			      const struct yaffs_ext_tags *etags)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	int chunk_bytes = dev->data_bytes_per_chunk;
> +	loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
> +	struct mtd_oob_ops ops;
> +	struct yaffs_packed_tags1 pt1;
> +	int retval;
> +
> +	/* we assume that packed_tags1 and struct yaffs_tags are compatible */
> +	compile_time_assertion(sizeof(struct yaffs_packed_tags1) == 12);
> +	compile_time_assertion(sizeof(struct yaffs_tags) == 8);

Can use one of the BUILD_BUG_ON macros rather than rolling your own?

> +
> +	yaffs_pack_tags1(&pt1, etags);
> +	yaffs_calc_tags_ecc((struct yaffs_tags *)&pt1);
> +
> +	/* When deleting a chunk, the upper layer provides only skeletal
> +	 * etags, one with is_deleted set.  However, we need to update the
> +	 * tags, not erase them completely.  So we use the NAND write property
> +	 * that only zeroed-bits stick and set tag bytes to all-ones and
> +	 * zero just the (not) deleted bit.
> +	 */
> +#ifndef CONFIG_YAFFS_9BYTE_TAGS
> +	if (etags->is_deleted) {
> +		memset(&pt1, 0xff, 8);
> +		/* clear delete status bit to indicate deleted */
> +		pt1.deleted = 0;
> +	}
> +#else
> +	((u8 *) &pt1)[8] = 0xff;
> +	if (etags->is_deleted) {
> +		memset(&pt1, 0xff, 8);
> +		/* zero page_status byte to indicate deleted */
> +		((u8 *) &pt1)[8] = 0;
> +	}
> +#endif
> +
> +	memset(&ops, 0, sizeof(ops));
> +	ops.mode = MTD_OOB_AUTO;
> +	ops.len = (data) ? chunk_bytes : 0;
> +	ops.ooblen = YTAG1_SIZE;
> +	ops.datbuf = (u8 *) data;
> +	ops.oobbuf = (u8 *) &pt1;
> +
> +	retval = mtd->write_oob(mtd, addr, &ops);
> +	if (retval) {
> +		yaffs_trace(YAFFS_TRACE_MTD,
> +			"write_oob failed, chunk %d, mtd error %d",
> +			nand_chunk, retval);
> +	}
> +	return retval ? YAFFS_FAIL : YAFFS_OK;
> +}
> +
> +/* Return with empty ExtendedTags but add ecc_result.
> + */
> +static int rettags(struct yaffs_ext_tags *etags, int ecc_result, int retval)
> +{
> +	if (etags) {
> +		memset(etags, 0, sizeof(*etags));
> +		etags->ecc_result = ecc_result;
> +	}
> +	return retval;
> +}
> +
> +/* Read a chunk (page) from NAND.
> + *
> + * Caller expects ExtendedTags data to be usable even on error; that is,
> + * all members except ecc_result and block_bad are zeroed.
> + *
> + *  - Check ECC results for data (if applicable)
> + *  - Check for blank/erased block (return empty ExtendedTags if blank)
> + *  - Check the packed_tags1 mini-ECC (correct if necessary/possible)
> + *  - Convert packed_tags1 to ExtendedTags
> + *  - Update ecc_result and block_bad members to refect state.
> + *
> + * Returns YAFFS_OK or YAFFS_FAIL.
> + */
> +int nandmtd1_read_chunk_tags(struct yaffs_dev *dev,
> +			     int nand_chunk, u8 *data,
> +			     struct yaffs_ext_tags *etags)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	int chunk_bytes = dev->data_bytes_per_chunk;
> +	loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
> +	int eccres = YAFFS_ECC_RESULT_NO_ERROR;
> +	struct mtd_oob_ops ops;

Change this to:

	struct mtd_oob_ops ops = {0};

> +	struct yaffs_packed_tags1 pt1;
> +	int retval;
> +	int deleted;
> +
> +	memset(&ops, 0, sizeof(ops));

and then remove this memset.

> +	ops.mode = MTD_OOB_AUTO;
> +	ops.len = (data) ? chunk_bytes : 0;
> +	ops.ooblen = YTAG1_SIZE;
> +	ops.datbuf = data;
> +	ops.oobbuf = (u8 *) &pt1;
> +
> +	/* Read page and oob using MTD.
> +	 * Check status and determine ECC result.
> +	 */
> +	retval = mtd->read_oob(mtd, addr, &ops);
> +	if (retval) {
> +		yaffs_trace(YAFFS_TRACE_MTD,
> +			"read_oob failed, chunk %d, mtd error %d",
> +			nand_chunk, retval);
> +	}
> +
> +	switch (retval) {
> +	case 0:
> +		/* no error */
> +		break;
> +
> +	case -EUCLEAN:
> +		/* MTD's ECC fixed the data */
> +		eccres = YAFFS_ECC_RESULT_FIXED;
> +		dev->n_ecc_fixed++;
> +		break;
> +
> +	case -EBADMSG:
> +		/* MTD's ECC could not fix the data */
> +		dev->n_ecc_unfixed++;
> +		/* fall into... */
> +	default:
> +		rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
> +		etags->block_bad = (mtd->block_isbad) (mtd, addr);
> +		return YAFFS_FAIL;
> +	}
> +
> +	/* Check for a blank/erased chunk.
> +	 */
> +	if (yaffs_check_ff((u8 *) &pt1, 8)) {
> +		/* when blank, upper layers want ecc_result to be <= NO_ERROR */
> +		return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
> +	}
> +#ifndef CONFIG_YAFFS_9BYTE_TAGS
> +	/* Read deleted status (bit) then return it to it's non-deleted
> +	 * state before performing tags mini-ECC check. pt1.deleted is
> +	 * inverted.
> +	 */
> +	deleted = !pt1.deleted;
> +	pt1.deleted = 1;
> +#else
> +	deleted = (hweight8(((u8 *) &pt1)[8]) < 7);
> +#endif
> +
> +	/* Check the packed tags mini-ECC and correct if necessary/possible.
> +	 */
> +	retval = yaffs_check_tags_ecc((struct yaffs_tags *)&pt1);
> +	switch (retval) {
> +	case 0:
> +		/* no tags error, use MTD result */
> +		break;
> +	case 1:
> +		/* recovered tags-ECC error */
> +		dev->n_tags_ecc_fixed++;
> +		if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
> +			eccres = YAFFS_ECC_RESULT_FIXED;
> +		break;
> +	default:
> +		/* unrecovered tags-ECC error */
> +		dev->n_tags_ecc_unfixed++;
> +		return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
> +	}
> +
> +	/* Unpack the tags to extended form and set ECC result.
> +	 * [set should_be_ff just to keep yaffs_unpack_tags1 happy]
> +	 */
> +	pt1.should_be_ff = 0xFFFFFFFF;
> +	yaffs_unpack_tags1(etags, &pt1);
> +	etags->ecc_result = eccres;
> +
> +	/* Set deleted state */
> +	etags->is_deleted = deleted;
> +	return YAFFS_OK;
> +}
> +
> +/* Mark a block bad.
> + *
> + * This is a persistant state.
> + * Use of this function should be rare.
> + *
> + * Returns YAFFS_OK or YAFFS_FAIL.
> + */
> +int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
> +	int retval;
> +
> +	yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
> +		"marking block %d bad", block_no);
> +
> +	retval = mtd->block_markbad(mtd, (loff_t) blocksize * block_no);
> +	return (retval) ? YAFFS_FAIL : YAFFS_OK;
> +}
> +
> +/* Check any MTD prerequists.
> + *
> + * Returns YAFFS_OK or YAFFS_FAIL.
> + */
> +static int nandmtd1_test_prerequists(struct mtd_info *mtd)
> +{
> +	/* 2.6.18 has mtd->ecclayout->oobavail */
> +	/* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */

This comment is not applicable for mainline.

> +	int oobavail = mtd->ecclayout->oobavail;
> +
> +	if (oobavail < YTAG1_SIZE) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"mtd device has only %d bytes for tags, need %d",
> +			oobavail, YTAG1_SIZE);
> +		return YAFFS_FAIL;
> +	}
> +	return YAFFS_OK;
> +}
> +
> +/* Query for the current state of a specific block.
> + *
> + * Examine the tags of the first chunk of the block and return the state:
> + *  - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
> + *  - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
> + *  - YAFFS_BLOCK_STATE_EMPTY, the block is clean
> + *
> + * Always returns YAFFS_OK.
> + */
> +int nandmtd1_query_block(struct yaffs_dev *dev, int block_no,
> +			 enum yaffs_block_state *state_ptr, u32 * seq_ptr)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	int chunk_num = block_no * dev->param.chunks_per_block;
> +	loff_t addr = (loff_t) chunk_num * dev->data_bytes_per_chunk;
> +	struct yaffs_ext_tags etags;
> +	int state = YAFFS_BLOCK_STATE_DEAD;
> +	int seqnum = 0;
> +	int retval;
> +
> +	/* We don't yet have a good place to test for MTD config prerequists.
> +	 * Do it here as we are called during the initial scan.
> +	 */
> +	if (nandmtd1_test_prerequists(mtd) != YAFFS_OK)
> +		return YAFFS_FAIL;
> +
> +	retval = nandmtd1_read_chunk_tags(dev, chunk_num, NULL, &etags);
> +	etags.block_bad = (mtd->block_isbad) (mtd, addr);
> +	if (etags.block_bad) {
> +		yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
> +			"block %d is marked bad", block_no);
> +		state = YAFFS_BLOCK_STATE_DEAD;
> +	} else if (etags.ecc_result != YAFFS_ECC_RESULT_NO_ERROR) {
> +		/* bad tags, need to look more closely */
> +		state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
> +	} else if (etags.chunk_used) {
> +		state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
> +		seqnum = etags.seq_number;
> +	} else {
> +		state = YAFFS_BLOCK_STATE_EMPTY;
> +	}
> +
> +	*state_ptr = state;
> +	*seq_ptr = seqnum;
> +
> +	/* query always succeeds */
> +	return YAFFS_OK;
> +}
> diff --git a/fs/yaffs2/yaffs_mtdif1.h b/fs/yaffs2/yaffs_mtdif1.h
> new file mode 100644
> index 0000000..034c680
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_mtdif1.h
> @@ -0,0 +1,29 @@
> +/*
> + * YAFFS: Yet another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_MTDIF1_H__
> +#define __YAFFS_MTDIF1_H__
> +
> +int nandmtd1_write_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
> +			      const u8 *data,
> +			      const struct yaffs_ext_tags *tags);
> +
> +int nandmtd1_read_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
> +			     u8 *data, struct yaffs_ext_tags *tags);
> +
> +int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no);
> +
> +int nandmtd1_query_block(struct yaffs_dev *dev, int block_no,
> +			 enum yaffs_block_state *state, u32 *seq_number);
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_mtdif2.c b/fs/yaffs2/yaffs_mtdif2.c
> new file mode 100644
> index 0000000..18340bd
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_mtdif2.c
> @@ -0,0 +1,215 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +/* mtd interface for YAFFS2 */
> +
> +#include "yportenv.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_mtdif2.h"
> +#include "yaffs_packedtags2.h"
> +#include "yaffs_linux.h"
> +#include "linux/mtd/mtd.h"
> +#include "linux/types.h"
> +#include "linux/time.h"
> +
> +
> +/* NB For use with inband tags....
> + * We assume that the data buffer is of size total_bytes_per_chunk so that
> + * we can also use it to load the tags.
> + */
> +int nandmtd2_write_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
> +			      const u8 *data,
> +			      const struct yaffs_ext_tags *tags)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	struct mtd_oob_ops ops;
> +	int retval = 0;
> +	loff_t addr;
> +	struct yaffs_packed_tags2 pt;
> +	int packed_tags_size =
> +	    dev->param.no_tags_ecc ? sizeof(pt.t) : sizeof(pt);
> +	void *packed_tags_ptr =
> +	    dev->param.no_tags_ecc ? (void *)&pt.t : (void *)&pt;

Shouldn't need void * casts.

> +
> +	yaffs_trace(YAFFS_TRACE_MTD,
> +		"nandmtd2_write_chunk_tags chunk %d data %p tags %p",
> +		nand_chunk, data, tags);
> +
> +	addr = ((loff_t) nand_chunk) * dev->param.total_bytes_per_chunk;
> +
> +	/* For yaffs2 writing there must be both data and tags.
> +	 * If we're using inband tags, then the tags are stuffed into
> +	 * the end of the data buffer.
> +	 */
> +	if (!data || !tags)
> +		BUG();
> +	else if (dev->param.inband_tags) {

This should be a separate if statement to the one for BUG. If you don't
want fall through when BUG is not enabled, then just have:

	if (!data || !tags) {
		BUG();
		return YAFFS_FAILED;
	}

> +		struct yaffs_packed_tags2_tags_only *pt2tp;
> +
> +		pt2tp =
> +		    (struct yaffs_packed_tags2_tags_only *)(data +
> +							dev->
> +							data_bytes_per_chunk);
> +		yaffs_pack_tags2_tags_only(pt2tp, tags);
> +	} else {
> +		yaffs_pack_tags2(&pt, tags, !dev->param.no_tags_ecc);
> +	}
> +
> +	ops.mode = MTD_OOB_AUTO;
> +	ops.ooblen = (dev->param.inband_tags) ? 0 : packed_tags_size;
> +	ops.len = dev->param.total_bytes_per_chunk;
> +	ops.ooboffs = 0;
> +	ops.datbuf = (u8 *) data;
> +	ops.oobbuf = (dev->param.inband_tags) ? NULL : packed_tags_ptr;
> +	retval = mtd->write_oob(mtd, addr, &ops);
> +
> +	if (retval == 0)
> +		return YAFFS_OK;
> +	else
> +		return YAFFS_FAIL;
> +}
> +
> +int nandmtd2_read_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
> +			     u8 *data, struct yaffs_ext_tags *tags)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	struct mtd_oob_ops ops;
> +	size_t dummy;
> +	int retval = 0;
> +	int local_data = 0;
> +	loff_t addr = ((loff_t) nand_chunk) * dev->param.total_bytes_per_chunk;
> +	struct yaffs_packed_tags2 pt;
> +	int packed_tags_size =
> +	    dev->param.no_tags_ecc ? sizeof(pt.t) : sizeof(pt);
> +	void *packed_tags_ptr =
> +	    dev->param.no_tags_ecc ? (void *)&pt.t : (void *)&pt;

Shouldn't need void * casts.

> +	yaffs_trace(YAFFS_TRACE_MTD,
> +		"nandmtd2_read_chunk_tags chunk %d data %p tags %p",
> +		nand_chunk, data, tags);
> +
> +	if (dev->param.inband_tags) {
> +
> +		if (!data) {

if (dev->param.inband_tags && !data) ?

> +			local_data = 1;
> +			data = yaffs_get_temp_buffer(dev, __LINE__);
> +		}
> +	}
> +
> +	if (dev->param.inband_tags || (data && !tags))
> +		retval = mtd->read(mtd, addr, dev->param.total_bytes_per_chunk,
> +				   &dummy, data);
> +	else if (tags) {
> +		ops.mode = MTD_OOB_AUTO;
> +		ops.ooblen = packed_tags_size;
> +		ops.len = data ? dev->data_bytes_per_chunk : packed_tags_size;
> +		ops.ooboffs = 0;
> +		ops.datbuf = data;
> +		ops.oobbuf = yaffs_dev_to_lc(dev)->spare_buffer;
> +		retval = mtd->read_oob(mtd, addr, &ops);
> +	}
> +
> +	if (dev->param.inband_tags) {
> +		if (tags) {
> +			struct yaffs_packed_tags2_tags_only *pt2tp;
> +			pt2tp =
> +				(struct yaffs_packed_tags2_tags_only *)
> +					&data[dev->data_bytes_per_chunk];
> +			yaffs_unpack_tags2_tags_only(tags, pt2tp);
> +		}
> +	} else {
> +		if (tags) {
> +			memcpy(packed_tags_ptr,
> +			       yaffs_dev_to_lc(dev)->spare_buffer,
> +			       packed_tags_size);
> +			yaffs_unpack_tags2(tags, &pt, !dev->param.no_tags_ecc);
> +		}
> +	}
> +
> +	if (local_data)
> +		yaffs_release_temp_buffer(dev, data, __LINE__);
> +
> +	if (tags && retval == -EBADMSG
> +	    && tags->ecc_result == YAFFS_ECC_RESULT_NO_ERROR) {
> +		tags->ecc_result = YAFFS_ECC_RESULT_UNFIXED;
> +		dev->n_ecc_unfixed++;
> +	}
> +	if (tags && retval == -EUCLEAN
> +	    && tags->ecc_result == YAFFS_ECC_RESULT_NO_ERROR) {
> +		tags->ecc_result = YAFFS_ECC_RESULT_FIXED;
> +		dev->n_ecc_fixed++;
> +	}
> +	if (retval == 0)
> +		return YAFFS_OK;
> +	else
> +		return YAFFS_FAIL;
> +}
> +
> +int nandmtd2_mark_block_bad(struct yaffs_dev *dev, int block_no)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	int retval;
> +
> +	yaffs_trace(YAFFS_TRACE_MTD,
> +		"nandmtd2_mark_block_bad %d", block_no);
> +
> +	retval =
> +	    mtd->block_markbad(mtd,
> +			       block_no * dev->param.chunks_per_block *
> +			       dev->param.total_bytes_per_chunk);
> +
> +	if (retval == 0)
> +		return YAFFS_OK;
> +	else
> +		return YAFFS_FAIL;
> +}
> +
> +int nandmtd2_query_block(struct yaffs_dev *dev, int block_no,
> +			 enum yaffs_block_state *state, u32 * seq_number)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
> +	int retval;
> +
> +	yaffs_trace(YAFFS_TRACE_MTD, "nandmtd2_query_block %d", block_no);
> +	retval =
> +	    mtd->block_isbad(mtd,
> +			     block_no * dev->param.chunks_per_block *
> +			     dev->param.total_bytes_per_chunk);
> +
> +	if (retval) {
> +		yaffs_trace(YAFFS_TRACE_MTD, "block is bad");
> +
> +		*state = YAFFS_BLOCK_STATE_DEAD;
> +		*seq_number = 0;
> +	} else {
> +		struct yaffs_ext_tags t;
> +		nandmtd2_read_chunk_tags(dev, block_no *
> +					 dev->param.chunks_per_block, NULL, &t);
> +
> +		if (t.chunk_used) {
> +			*seq_number = t.seq_number;
> +			*state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
> +		} else {
> +			*seq_number = 0;
> +			*state = YAFFS_BLOCK_STATE_EMPTY;
> +		}
> +	}
> +	yaffs_trace(YAFFS_TRACE_MTD,
> +		"block is bad seq %d state %d", *seq_number, *state);
> +
> +	if (retval == 0)
> +		return YAFFS_OK;
> +	else
> +		return YAFFS_FAIL;
> +}
> +
> diff --git a/fs/yaffs2/yaffs_mtdif2.h b/fs/yaffs2/yaffs_mtdif2.h
> new file mode 100644
> index 0000000..78babf5
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_mtdif2.h
> @@ -0,0 +1,29 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_MTDIF2_H__
> +#define __YAFFS_MTDIF2_H__
> +
> +#include "yaffs_guts.h"
> +int nandmtd2_write_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
> +			      const u8 *data,
> +			      const struct yaffs_ext_tags *tags);
> +int nandmtd2_read_chunk_tags(struct yaffs_dev *dev, int nand_chunk,
> +			     u8 *data, struct yaffs_ext_tags *tags);
> +int nandmtd2_mark_block_bad(struct yaffs_dev *dev, int block_no);
> +int nandmtd2_query_block(struct yaffs_dev *dev, int block_no,
> +			 enum yaffs_block_state *state, u32 *seq_number);
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_nand.c b/fs/yaffs2/yaffs_nand.c
> new file mode 100644
> index 0000000..ee061a8
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_nand.c
> @@ -0,0 +1,120 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_nand.h"
> +#include "yaffs_tagscompat.h"
> +#include "yaffs_tagsvalidity.h"
> +
> +#include "yaffs_getblockinfo.h"
> +
> +int yaffs_rd_chunk_tags_nand(struct yaffs_dev *dev, int nand_chunk,
> +			     u8 *buffer, struct yaffs_ext_tags *tags)
> +{
> +	int result;
> +	struct yaffs_ext_tags local_tags;
> +	int realigned_chunk = nand_chunk - dev->chunk_offset;
> +
> +	dev->n_page_reads++;
> +
> +	/* If there are no tags provided use local tags. */
> +	if (!tags)
> +		tags = &local_tags;
> +
> +	if (dev->param.read_chunk_tags_fn)
> +		result =
> +		    dev->param.read_chunk_tags_fn(dev, realigned_chunk, buffer,
> +						  tags);
> +	else
> +		result = yaffs_tags_compat_rd(dev,
> +					      realigned_chunk, buffer, tags);
> +	if (tags && tags->ecc_result > YAFFS_ECC_RESULT_NO_ERROR) {
> +
> +		struct yaffs_block_info *bi;
> +		bi = yaffs_get_block_info(dev,
> +					  nand_chunk /
> +					  dev->param.chunks_per_block);
> +		yaffs_handle_chunk_error(dev, bi);
> +	}
> +	return result;
> +}
> +
> +int yaffs_wr_chunk_tags_nand(struct yaffs_dev *dev,
> +				int nand_chunk,
> +				const u8 *buffer, struct yaffs_ext_tags *tags)
> +{
> +	dev->n_page_writes++;
> +	nand_chunk -= dev->chunk_offset;
> +
> +	if (tags) {
> +		tags->seq_number = dev->seq_number;
> +		tags->chunk_used = 1;
> +		if (!yaffs_validate_tags(tags)) {
> +			yaffs_trace(YAFFS_TRACE_ERROR,
> +				"Writing uninitialised tags");
> +			YBUG();
> +		}
> +		yaffs_trace(YAFFS_TRACE_WRITE,
> +			"Writing chunk %d tags %d %d",
> +			nand_chunk, tags->obj_id, tags->chunk_id);
> +	} else {
> +		yaffs_trace(YAFFS_TRACE_ERROR, "Writing with no tags");
> +		YBUG();
> +		return YAFFS_FAIL;
> +	}

I would rearrange this to make the BUG case prominent and then drop the
indentation for the case where tags is valid, ie:

	if (!tags) {
		yaffs_trace(YAFFS_TRACE_ERROR, "Writing with no tags");
		YBUG();
		return YAFFS_FAIL;
	}

	tags->seq_number = dev->seq_number;
	...

> +
> +	if (dev->param.write_chunk_tags_fn)
> +		return dev->param.write_chunk_tags_fn(dev, nand_chunk, buffer,
> +							tags);
> +	else
> +		return yaffs_tags_compat_wr(dev, nand_chunk, buffer, tags);
> +}
> +
> +int yaffs_mark_bad(struct yaffs_dev *dev, int block_no)
> +{
> +	block_no -= dev->block_offset;
> +	if (dev->param.bad_block_fn)
> +		return dev->param.bad_block_fn(dev, block_no);
> +	else
> +		return yaffs_tags_compat_mark_bad(dev, block_no);
> +}
> +
> +int yaffs_query_init_block_state(struct yaffs_dev *dev,
> +				 int block_no,
> +				 enum yaffs_block_state *state,
> +				 u32 *seq_number)
> +{
> +	block_no -= dev->block_offset;
> +	if (dev->param.query_block_fn)
> +		return dev->param.query_block_fn(dev, block_no, state,
> +						 seq_number);
> +	else
> +		return yaffs_tags_compat_query_block(dev, block_no,
> +						     state, seq_number);
> +}
> +
> +int yaffs_erase_block(struct yaffs_dev *dev, int flash_block)
> +{
> +	int result;
> +
> +	flash_block -= dev->block_offset;
> +	dev->n_erasures++;
> +	result = dev->param.erase_fn(dev, flash_block);
> +	return result;

Just:
	return dev->param.erase_fn(dev, flash_block);

> +}
> +
> +int yaffs_init_nand(struct yaffs_dev *dev)
> +{
> +	if (dev->param.initialise_flash_fn)
> +		return dev->param.initialise_flash_fn(dev);
> +	return YAFFS_OK;
> +}
> diff --git a/fs/yaffs2/yaffs_nand.h b/fs/yaffs2/yaffs_nand.h
> new file mode 100644
> index 0000000..a36498a
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_nand.h
> @@ -0,0 +1,38 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_NAND_H__
> +#define __YAFFS_NAND_H__
> +#include "yaffs_guts.h"
> +
> +int yaffs_rd_chunk_tags_nand(struct yaffs_dev *dev, int nand_chunk,
> +			     u8 *buffer, struct yaffs_ext_tags *tags);
> +
> +int yaffs_wr_chunk_tags_nand(struct yaffs_dev *dev,
> +			     int nand_chunk,
> +			     const u8 *buffer, struct yaffs_ext_tags *tags);
> +
> +int yaffs_mark_bad(struct yaffs_dev *dev, int block_no);
> +
> +int yaffs_query_init_block_state(struct yaffs_dev *dev,
> +				 int block_no,
> +				 enum yaffs_block_state *state,
> +				 unsigned *seq_number);
> +
> +int yaffs_erase_block(struct yaffs_dev *dev, int flash_block);
> +
> +int yaffs_init_nand(struct yaffs_dev *dev);
> +
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 05/10] Add yaffs2 file system: Tags processing code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_packedtags1.c |   53 ++++++
 fs/yaffs2/yaffs_packedtags1.h |   39 ++++
 fs/yaffs2/yaffs_packedtags2.c |  187 +++++++++++++++++++
 fs/yaffs2/yaffs_packedtags2.h |   47 +++++
 fs/yaffs2/yaffs_tagscompat.c  |  413 +++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_tagscompat.h  |   36 ++++
 6 files changed, 775 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_packedtags1.c
 create mode 100644 fs/yaffs2/yaffs_packedtags1.h
 create mode 100644 fs/yaffs2/yaffs_packedtags2.c
 create mode 100644 fs/yaffs2/yaffs_packedtags2.h
 create mode 100644 fs/yaffs2/yaffs_tagscompat.c
 create mode 100644 fs/yaffs2/yaffs_tagscompat.h

diff --git a/fs/yaffs2/yaffs_packedtags1.c b/fs/yaffs2/yaffs_packedtags1.c
new file mode 100644
index 0000000..873f065
--- /dev/null
+++ b/fs/yaffs2/yaffs_packedtags1.c
@@ -0,0 +1,53 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_packedtags1.h"
+#include "yportenv.h"
+
+void yaffs_pack_tags1(struct yaffs_packed_tags1 *pt,
+		      const struct yaffs_ext_tags *t)
+{
+	pt->chunk_id = t->chunk_id;
+	pt->serial_number = t->serial_number;
+	pt->n_bytes = t->n_bytes;
+	pt->obj_id = t->obj_id;
+	pt->ecc = 0;
+	pt->deleted = (t->is_deleted) ? 0 : 1;
+	pt->unused_stuff = 0;
+	pt->should_be_ff = 0xFFFFFFFF;
+}
+
+void yaffs_unpack_tags1(struct yaffs_ext_tags *t,
+			const struct yaffs_packed_tags1 *pt)
+{
+	static const u8 all_ff[12] = {
+		0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff
+	};
+
+	if (memcmp(all_ff, pt, sizeof(struct yaffs_packed_tags1))) {
+		t->block_bad = 0;
+		if (pt->should_be_ff != 0xFFFFFFFF)
+			t->block_bad = 1;
+		t->chunk_used = 1;
+		t->obj_id = pt->obj_id;
+		t->chunk_id = pt->chunk_id;
+		t->n_bytes = pt->n_bytes;
+		t->ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
+		t->is_deleted = (pt->deleted) ? 0 : 1;
+		t->serial_number = pt->serial_number;
+	} else {
+		memset(t, 0, sizeof(struct yaffs_ext_tags));
+	}
+}
diff --git a/fs/yaffs2/yaffs_packedtags1.h b/fs/yaffs2/yaffs_packedtags1.h
new file mode 100644
index 0000000..d6861ff
--- /dev/null
+++ b/fs/yaffs2/yaffs_packedtags1.h
@@ -0,0 +1,39 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+/* This is used to pack YAFFS1 tags, not YAFFS2 tags. */
+
+#ifndef __YAFFS_PACKEDTAGS1_H__
+#define __YAFFS_PACKEDTAGS1_H__
+
+#include "yaffs_guts.h"
+
+struct yaffs_packed_tags1 {
+	unsigned chunk_id:20;
+	unsigned serial_number:2;
+	unsigned n_bytes:10;
+	unsigned obj_id:18;
+	unsigned ecc:12;
+	unsigned deleted:1;
+	unsigned unused_stuff:1;
+	unsigned should_be_ff;
+
+};
+
+void yaffs_pack_tags1(struct yaffs_packed_tags1 *pt,
+		      const struct yaffs_ext_tags *t);
+void yaffs_unpack_tags1(struct yaffs_ext_tags *t,
+			const struct yaffs_packed_tags1 *pt);
+#endif
diff --git a/fs/yaffs2/yaffs_packedtags2.c b/fs/yaffs2/yaffs_packedtags2.c
new file mode 100644
index 0000000..2bb31b0
--- /dev/null
+++ b/fs/yaffs2/yaffs_packedtags2.c
@@ -0,0 +1,187 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_packedtags2.h"
+#include "yportenv.h"
+#include "yaffs_trace.h"
+#include "yaffs_tagsvalidity.h"
+
+/* This code packs a set of extended tags into a binary structure for
+ * NAND storage
+ */
+
+/* Some of the information is "extra" struff which can be packed in to
+ * speed scanning
+ * This is defined by having the EXTRA_HEADER_INFO_FLAG set.
+ */
+
+/* Extra flags applied to chunk_id */
+
+#define EXTRA_HEADER_INFO_FLAG	0x80000000
+#define EXTRA_SHRINK_FLAG	0x40000000
+#define EXTRA_SHADOWS_FLAG	0x20000000
+#define EXTRA_SPARE_FLAGS	0x10000000
+
+#define ALL_EXTRA_FLAGS		0xF0000000
+
+/* Also, the top 4 bits of the object Id are set to the object type. */
+#define EXTRA_OBJECT_TYPE_SHIFT (28)
+#define EXTRA_OBJECT_TYPE_MASK  ((0x0F) << EXTRA_OBJECT_TYPE_SHIFT)
+
+static void yaffs_dump_packed_tags2_tags_only(
+				const struct yaffs_packed_tags2_tags_only *ptt)
+{
+	yaffs_trace(YAFFS_TRACE_MTD,
+		"packed tags obj %d chunk %d byte %d seq %d",
+		ptt->obj_id, ptt->chunk_id, ptt->n_bytes, ptt->seq_number);
+}
+
+static void yaffs_dump_packed_tags2(const struct yaffs_packed_tags2 *pt)
+{
+	yaffs_dump_packed_tags2_tags_only(&pt->t);
+}
+
+static void yaffs_dump_tags2(const struct yaffs_ext_tags *t)
+{
+	yaffs_trace(YAFFS_TRACE_MTD,
+		"ext.tags eccres %d blkbad %d chused %d obj %d chunk%d byte %d del %d ser %d seq %d",
+		t->ecc_result, t->block_bad, t->chunk_used, t->obj_id,
+		t->chunk_id, t->n_bytes, t->is_deleted, t->serial_number,
+		t->seq_number);
+
+}
+
+void yaffs_pack_tags2_tags_only(struct yaffs_packed_tags2_tags_only *ptt,
+				const struct yaffs_ext_tags *t)
+{
+	ptt->chunk_id = t->chunk_id;
+	ptt->seq_number = t->seq_number;
+	ptt->n_bytes = t->n_bytes;
+	ptt->obj_id = t->obj_id;
+
+	if (t->chunk_id == 0 && t->extra_available) {
+		/* Store the extra header info instead */
+		/* We save the parent object in the chunk_id */
+		ptt->chunk_id = EXTRA_HEADER_INFO_FLAG | t->extra_parent_id;
+		if (t->extra_is_shrink)
+			ptt->chunk_id |= EXTRA_SHRINK_FLAG;
+		if (t->extra_shadows)
+			ptt->chunk_id |= EXTRA_SHADOWS_FLAG;
+
+		ptt->obj_id &= ~EXTRA_OBJECT_TYPE_MASK;
+		ptt->obj_id |= (t->extra_obj_type << EXTRA_OBJECT_TYPE_SHIFT);
+
+		if (t->extra_obj_type == YAFFS_OBJECT_TYPE_HARDLINK)
+			ptt->n_bytes = t->extra_equiv_id;
+		else if (t->extra_obj_type == YAFFS_OBJECT_TYPE_FILE)
+			ptt->n_bytes = t->extra_length;
+		else
+			ptt->n_bytes = 0;
+	}
+
+	yaffs_dump_packed_tags2_tags_only(ptt);
+	yaffs_dump_tags2(t);
+}
+
+void yaffs_pack_tags2(struct yaffs_packed_tags2 *pt,
+		      const struct yaffs_ext_tags *t, int tags_ecc)
+{
+	yaffs_pack_tags2_tags_only(&pt->t, t);
+
+	if (tags_ecc)
+		yaffs_ecc_calc_other((unsigned char *)&pt->t,
+				     sizeof(struct
+					    yaffs_packed_tags2_tags_only),
+				     &pt->ecc);
+}
+
+void yaffs_unpack_tags2_tags_only(struct yaffs_ext_tags *t,
+				  struct yaffs_packed_tags2_tags_only *ptt)
+{
+	memset(t, 0, sizeof(struct yaffs_ext_tags));
+	yaffs_init_tags(t);
+
+	if (ptt->seq_number != 0xFFFFFFFF) {
+		t->block_bad = 0;
+		t->chunk_used = 1;
+		t->obj_id = ptt->obj_id;
+		t->chunk_id = ptt->chunk_id;
+		t->n_bytes = ptt->n_bytes;
+		t->is_deleted = 0;
+		t->serial_number = 0;
+		t->seq_number = ptt->seq_number;
+
+		/* Do extra header info stuff */
+		if (ptt->chunk_id & EXTRA_HEADER_INFO_FLAG) {
+			t->chunk_id = 0;
+			t->n_bytes = 0;
+
+			t->extra_available = 1;
+			t->extra_parent_id =
+			    ptt->chunk_id & (~(ALL_EXTRA_FLAGS));
+			t->extra_is_shrink =
+			    (ptt->chunk_id & EXTRA_SHRINK_FLAG) ? 1 : 0;
+			t->extra_shadows =
+			    (ptt->chunk_id & EXTRA_SHADOWS_FLAG) ? 1 : 0;
+			t->extra_obj_type =
+			    ptt->obj_id >> EXTRA_OBJECT_TYPE_SHIFT;
+			t->obj_id &= ~EXTRA_OBJECT_TYPE_MASK;
+
+			if (t->extra_obj_type == YAFFS_OBJECT_TYPE_HARDLINK)
+				t->extra_equiv_id = ptt->n_bytes;
+			else
+				t->extra_length = ptt->n_bytes;
+		}
+	}
+	yaffs_dump_packed_tags2_tags_only(ptt);
+	yaffs_dump_tags2(t);
+}
+
+void yaffs_unpack_tags2(struct yaffs_ext_tags *t, struct yaffs_packed_tags2 *pt,
+			int tags_ecc)
+{
+	enum yaffs_ecc_result ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
+
+	if (pt->t.seq_number != 0xFFFFFFFF && tags_ecc) {
+		/* Chunk is in use and we need to do ECC */
+
+		struct yaffs_ecc_other ecc;
+		int result;
+		yaffs_ecc_calc_other((unsigned char *)&pt->t,
+				sizeof(struct yaffs_packed_tags2_tags_only),
+				&ecc);
+		result =
+		    yaffs_ecc_correct_other((unsigned char *)&pt->t,
+				sizeof(struct yaffs_packed_tags2_tags_only),
+				&pt->ecc, &ecc);
+		switch (result) {
+		case 0:
+			ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
+			break;
+		case 1:
+			ecc_result = YAFFS_ECC_RESULT_FIXED;
+			break;
+		case -1:
+			ecc_result = YAFFS_ECC_RESULT_UNFIXED;
+			break;
+		default:
+			ecc_result = YAFFS_ECC_RESULT_UNKNOWN;
+		}
+	}
+	yaffs_unpack_tags2_tags_only(t, &pt->t);
+
+	t->ecc_result = ecc_result;
+
+	yaffs_dump_packed_tags2(pt);
+	yaffs_dump_tags2(t);
+}
diff --git a/fs/yaffs2/yaffs_packedtags2.h b/fs/yaffs2/yaffs_packedtags2.h
new file mode 100644
index 0000000..f329669
--- /dev/null
+++ b/fs/yaffs2/yaffs_packedtags2.h
@@ -0,0 +1,47 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+/* This is used to pack YAFFS2 tags, not YAFFS1tags. */
+
+#ifndef __YAFFS_PACKEDTAGS2_H__
+#define __YAFFS_PACKEDTAGS2_H__
+
+#include "yaffs_guts.h"
+#include "yaffs_ecc.h"
+
+struct yaffs_packed_tags2_tags_only {
+	unsigned seq_number;
+	unsigned obj_id;
+	unsigned chunk_id;
+	unsigned n_bytes;
+};
+
+struct yaffs_packed_tags2 {
+	struct yaffs_packed_tags2_tags_only t;
+	struct yaffs_ecc_other ecc;
+};
+
+/* Full packed tags with ECC, used for oob tags */
+void yaffs_pack_tags2(struct yaffs_packed_tags2 *pt,
+		      const struct yaffs_ext_tags *t, int tags_ecc);
+void yaffs_unpack_tags2(struct yaffs_ext_tags *t, struct yaffs_packed_tags2 *pt,
+			int tags_ecc);
+
+/* Only the tags part (no ECC for use with inband tags */
+void yaffs_pack_tags2_tags_only(struct yaffs_packed_tags2_tags_only *pt,
+				const struct yaffs_ext_tags *t);
+void yaffs_unpack_tags2_tags_only(struct yaffs_ext_tags *t,
+				  struct yaffs_packed_tags2_tags_only *pt);
+#endif
diff --git a/fs/yaffs2/yaffs_tagscompat.c b/fs/yaffs2/yaffs_tagscompat.c
new file mode 100644
index 0000000..35d33c9
--- /dev/null
+++ b/fs/yaffs2/yaffs_tagscompat.c
@@ -0,0 +1,413 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_guts.h"
+#include "yaffs_tagscompat.h"
+#include "yaffs_ecc.h"
+#include "yaffs_getblockinfo.h"
+#include "yaffs_trace.h"
+
+static void yaffs_handle_rd_data_error(struct yaffs_dev *dev, int nand_chunk);
+
+
+/********** Tags ECC calculations  *********/
+
+void yaffs_calc_ecc(const u8 *data, struct yaffs_spare *spare)
+{
+	yaffs_ecc_cacl(data, spare->ecc1);
+	yaffs_ecc_cacl(&data[256], spare->ecc2);
+}
+
+void yaffs_calc_tags_ecc(struct yaffs_tags *tags)
+{
+	/* Calculate an ecc */
+	unsigned char *b = ((union yaffs_tags_union *)tags)->as_bytes;
+	unsigned i, j;
+	unsigned ecc = 0;
+	unsigned bit = 0;
+
+	tags->ecc = 0;
+
+	for (i = 0; i < 8; i++) {
+		for (j = 1; j & 0xff; j <<= 1) {
+			bit++;
+			if (b[i] & j)
+				ecc ^= bit;
+		}
+	}
+	tags->ecc = ecc;
+}
+
+int yaffs_check_tags_ecc(struct yaffs_tags *tags)
+{
+	unsigned ecc = tags->ecc;
+
+	yaffs_calc_tags_ecc(tags);
+
+	ecc ^= tags->ecc;
+
+	if (ecc && ecc <= 64) {
+		/* TODO: Handle the failure better. Retire? */
+		unsigned char *b = ((union yaffs_tags_union *)tags)->as_bytes;
+
+		ecc--;
+
+		b[ecc / 8] ^= (1 << (ecc & 7));
+
+		/* Now recvalc the ecc */
+		yaffs_calc_tags_ecc(tags);
+
+		return 1;	/* recovered error */
+	} else if (ecc) {
+		/* Wierd ecc failure value */
+		/* TODO Need to do somethiong here */
+		return -1;	/* unrecovered error */
+	}
+	return 0;
+}
+
+/********** Tags **********/
+
+static void yaffs_load_tags_to_spare(struct yaffs_spare *spare_ptr,
+				     struct yaffs_tags *tags_ptr)
+{
+	union yaffs_tags_union *tu = (union yaffs_tags_union *)tags_ptr;
+
+	yaffs_calc_tags_ecc(tags_ptr);
+
+	spare_ptr->tb0 = tu->as_bytes[0];
+	spare_ptr->tb1 = tu->as_bytes[1];
+	spare_ptr->tb2 = tu->as_bytes[2];
+	spare_ptr->tb3 = tu->as_bytes[3];
+	spare_ptr->tb4 = tu->as_bytes[4];
+	spare_ptr->tb5 = tu->as_bytes[5];
+	spare_ptr->tb6 = tu->as_bytes[6];
+	spare_ptr->tb7 = tu->as_bytes[7];
+}
+
+static void yaffs_get_tags_from_spare(struct yaffs_dev *dev,
+				      struct yaffs_spare *spare_ptr,
+				      struct yaffs_tags *tags_ptr)
+{
+	union yaffs_tags_union *tu = (union yaffs_tags_union *)tags_ptr;
+	int result;
+
+	tu->as_bytes[0] = spare_ptr->tb0;
+	tu->as_bytes[1] = spare_ptr->tb1;
+	tu->as_bytes[2] = spare_ptr->tb2;
+	tu->as_bytes[3] = spare_ptr->tb3;
+	tu->as_bytes[4] = spare_ptr->tb4;
+	tu->as_bytes[5] = spare_ptr->tb5;
+	tu->as_bytes[6] = spare_ptr->tb6;
+	tu->as_bytes[7] = spare_ptr->tb7;
+
+	result = yaffs_check_tags_ecc(tags_ptr);
+	if (result > 0)
+		dev->n_tags_ecc_fixed++;
+	else if (result < 0)
+		dev->n_tags_ecc_unfixed++;
+}
+
+static void yaffs_spare_init(struct yaffs_spare *spare)
+{
+	memset(spare, 0xFF, sizeof(struct yaffs_spare));
+}
+
+static int yaffs_wr_nand(struct yaffs_dev *dev,
+			 int nand_chunk, const u8 *data,
+			 struct yaffs_spare *spare)
+{
+	if (nand_chunk < dev->param.start_block * dev->param.chunks_per_block) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"**>> yaffs chunk %d is not valid",
+			nand_chunk);
+		return YAFFS_FAIL;
+	}
+
+	return dev->param.write_chunk_fn(dev, nand_chunk, data, spare);
+}
+
+static int yaffs_rd_chunk_nand(struct yaffs_dev *dev,
+			       int nand_chunk,
+			       u8 *data,
+			       struct yaffs_spare *spare,
+			       enum yaffs_ecc_result *ecc_result,
+			       int correct_errors)
+{
+	int ret_val;
+	struct yaffs_spare local_spare;
+
+	if (!spare) {
+		/* If we don't have a real spare, then we use a local one. */
+		/* Need this for the calculation of the ecc */
+		spare = &local_spare;
+	}
+
+	if (!dev->param.use_nand_ecc) {
+		ret_val =
+		    dev->param.read_chunk_fn(dev, nand_chunk, data, spare);
+		if (data && correct_errors) {
+			/* Do ECC correction */
+			/* Todo handle any errors */
+			int ecc_result1, ecc_result2;
+			u8 calc_ecc[3];
+
+			yaffs_ecc_cacl(data, calc_ecc);
+			ecc_result1 =
+			    yaffs_ecc_correct(data, spare->ecc1, calc_ecc);
+			yaffs_ecc_cacl(&data[256], calc_ecc);
+			ecc_result2 =
+			    yaffs_ecc_correct(&data[256], spare->ecc2,
+					      calc_ecc);
+
+			if (ecc_result1 > 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>yaffs ecc error fix performed on chunk %d:0",
+					nand_chunk);
+				dev->n_ecc_fixed++;
+			} else if (ecc_result1 < 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>yaffs ecc error unfixed on chunk %d:0",
+					nand_chunk);
+				dev->n_ecc_unfixed++;
+			}
+
+			if (ecc_result2 > 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>yaffs ecc error fix performed on chunk %d:1",
+					nand_chunk);
+				dev->n_ecc_fixed++;
+			} else if (ecc_result2 < 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>yaffs ecc error unfixed on chunk %d:1",
+					nand_chunk);
+				dev->n_ecc_unfixed++;
+			}
+
+			if (ecc_result1 || ecc_result2) {
+				/* We had a data problem on this page */
+				yaffs_handle_rd_data_error(dev, nand_chunk);
+			}
+
+			if (ecc_result1 < 0 || ecc_result2 < 0)
+				*ecc_result = YAFFS_ECC_RESULT_UNFIXED;
+			else if (ecc_result1 > 0 || ecc_result2 > 0)
+				*ecc_result = YAFFS_ECC_RESULT_FIXED;
+			else
+				*ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
+		}
+	} else {
+		/* Must allocate enough memory for spare+2*sizeof(int) */
+		/* for ecc results from device. */
+		struct yaffs_nand_spare nspare;
+
+		memset(&nspare, 0, sizeof(nspare));
+
+		ret_val = dev->param.read_chunk_fn(dev, nand_chunk, data,
+						   (struct yaffs_spare *)
+						   &nspare);
+		memcpy(spare, &nspare, sizeof(struct yaffs_spare));
+		if (data && correct_errors) {
+			if (nspare.eccres1 > 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>mtd ecc error fix performed on chunk %d:0",
+					nand_chunk);
+			} else if (nspare.eccres1 < 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>mtd ecc error unfixed on chunk %d:0",
+					nand_chunk);
+			}
+
+			if (nspare.eccres2 > 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>mtd ecc error fix performed on chunk %d:1",
+					nand_chunk);
+			} else if (nspare.eccres2 < 0) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"**>>mtd ecc error unfixed on chunk %d:1",
+					nand_chunk);
+			}
+
+			if (nspare.eccres1 || nspare.eccres2) {
+				/* We had a data problem on this page */
+				yaffs_handle_rd_data_error(dev, nand_chunk);
+			}
+
+			if (nspare.eccres1 < 0 || nspare.eccres2 < 0)
+				*ecc_result = YAFFS_ECC_RESULT_UNFIXED;
+			else if (nspare.eccres1 > 0 || nspare.eccres2 > 0)
+				*ecc_result = YAFFS_ECC_RESULT_FIXED;
+			else
+				*ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
+
+		}
+	}
+	return ret_val;
+}
+
+/*
+ * Functions for robustisizing
+ */
+
+static void yaffs_handle_rd_data_error(struct yaffs_dev *dev, int nand_chunk)
+{
+	int flash_block = nand_chunk / dev->param.chunks_per_block;
+
+	/* Mark the block for retirement */
+	yaffs_get_block_info(dev, flash_block + dev->block_offset)->
+		needs_retiring = 1;
+	yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
+		"**>>Block %d marked for retirement",
+		flash_block);
+
+	/* TODO:
+	 * Just do a garbage collection on the affected block
+	 * then retire the block
+	 * NB recursion
+	 */
+}
+
+int yaffs_tags_compat_wr(struct yaffs_dev *dev,
+			 int nand_chunk,
+			 const u8 *data, const struct yaffs_ext_tags *ext_tags)
+{
+	struct yaffs_spare spare;
+	struct yaffs_tags tags;
+
+	yaffs_spare_init(&spare);
+
+	if (ext_tags->is_deleted)
+		spare.page_status = 0;
+	else {
+		tags.obj_id = ext_tags->obj_id;
+		tags.chunk_id = ext_tags->chunk_id;
+
+		tags.n_bytes_lsb = ext_tags->n_bytes & 0x3ff;
+
+		if (dev->data_bytes_per_chunk >= 1024)
+			tags.n_bytes_msb = (ext_tags->n_bytes >> 10) & 3;
+		else
+			tags.n_bytes_msb = 3;
+
+		tags.serial_number = ext_tags->serial_number;
+
+		if (!dev->param.use_nand_ecc && data)
+			yaffs_calc_ecc(data, &spare);
+
+		yaffs_load_tags_to_spare(&spare, &tags);
+
+	}
+
+	return yaffs_wr_nand(dev, nand_chunk, data, &spare);
+}
+
+int yaffs_tags_compat_rd(struct yaffs_dev *dev,
+			 int nand_chunk,
+			 u8 *data, struct yaffs_ext_tags *ext_tags)
+{
+	struct yaffs_spare spare;
+	struct yaffs_tags tags;
+	enum yaffs_ecc_result ecc_result = YAFFS_ECC_RESULT_UNKNOWN;
+	static struct yaffs_spare spare_ff;
+	static int init;
+
+	if (!init) {
+		memset(&spare_ff, 0xFF, sizeof(spare_ff));
+		init = 1;
+	}
+
+	if (yaffs_rd_chunk_nand(dev, nand_chunk,
+					data, &spare, &ecc_result, 1)) {
+		/* ext_tags may be NULL */
+		if (ext_tags) {
+
+			int deleted =
+			    (hweight8(spare.page_status) < 7) ? 1 : 0;
+
+			ext_tags->is_deleted = deleted;
+			ext_tags->ecc_result = ecc_result;
+			ext_tags->block_bad = 0;	/* We're reading it */
+			/* therefore it is not a bad block */
+			ext_tags->chunk_used =
+			    (memcmp(&spare_ff, &spare, sizeof(spare_ff)) !=
+			     0) ? 1 : 0;
+
+			if (ext_tags->chunk_used) {
+				yaffs_get_tags_from_spare(dev, &spare, &tags);
+
+				ext_tags->obj_id = tags.obj_id;
+				ext_tags->chunk_id = tags.chunk_id;
+				ext_tags->n_bytes = tags.n_bytes_lsb;
+
+				if (dev->data_bytes_per_chunk >= 1024)
+					ext_tags->n_bytes |=
+					    (((unsigned)tags.
+					      n_bytes_msb) << 10);
+
+				ext_tags->serial_number = tags.serial_number;
+			}
+		}
+
+		return YAFFS_OK;
+	} else {
+		return YAFFS_FAIL;
+	}
+}
+
+int yaffs_tags_compat_mark_bad(struct yaffs_dev *dev, int flash_block)
+{
+	struct yaffs_spare spare;
+
+	memset(&spare, 0xff, sizeof(struct yaffs_spare));
+
+	spare.block_status = 'Y';
+
+	yaffs_wr_nand(dev, flash_block * dev->param.chunks_per_block, NULL,
+		      &spare);
+	yaffs_wr_nand(dev, flash_block * dev->param.chunks_per_block + 1,
+		      NULL, &spare);
+
+	return YAFFS_OK;
+}
+
+int yaffs_tags_compat_query_block(struct yaffs_dev *dev,
+				  int block_no,
+				  enum yaffs_block_state *state,
+				  u32 *seq_number)
+{
+	struct yaffs_spare spare0, spare1;
+	static struct yaffs_spare spare_ff;
+	static int init;
+	enum yaffs_ecc_result dummy;
+
+	if (!init) {
+		memset(&spare_ff, 0xFF, sizeof(spare_ff));
+		init = 1;
+	}
+
+	*seq_number = 0;
+
+	yaffs_rd_chunk_nand(dev, block_no * dev->param.chunks_per_block, NULL,
+			    &spare0, &dummy, 1);
+	yaffs_rd_chunk_nand(dev, block_no * dev->param.chunks_per_block + 1,
+			    NULL, &spare1, &dummy, 1);
+
+	if (hweight8(spare0.block_status & spare1.block_status) < 7)
+		*state = YAFFS_BLOCK_STATE_DEAD;
+	else if (memcmp(&spare_ff, &spare0, sizeof(spare_ff)) == 0)
+		*state = YAFFS_BLOCK_STATE_EMPTY;
+	else
+		*state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
+
+	return YAFFS_OK;
+}
diff --git a/fs/yaffs2/yaffs_tagscompat.h b/fs/yaffs2/yaffs_tagscompat.h
new file mode 100644
index 0000000..ae15e0b
--- /dev/null
+++ b/fs/yaffs2/yaffs_tagscompat.h
@@ -0,0 +1,36 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_TAGSCOMPAT_H__
+#define __YAFFS_TAGSCOMPAT_H__
+
+#include "yaffs_guts.h"
+int yaffs_tags_compat_wr(struct yaffs_dev *dev,
+			 int nand_chunk,
+			 const u8 *data, const struct yaffs_ext_tags *tags);
+int yaffs_tags_compat_rd(struct yaffs_dev *dev,
+			 int nand_chunk,
+			 u8 *data, struct yaffs_ext_tags *tags);
+int yaffs_tags_compat_mark_bad(struct yaffs_dev *dev, int block_no);
+int yaffs_tags_compat_query_block(struct yaffs_dev *dev,
+				  int block_no,
+				  enum yaffs_block_state *state,
+				  u32 *seq_number);
+
+void yaffs_calc_tags_ecc(struct yaffs_tags *tags);
+int yaffs_check_tags_ecc(struct yaffs_tags *tags);
+int yaffs_count_bits(u8 byte);
+
+#endif
-- 
1.7.1

Re: [PATCH 05/10] Add yaffs2 file system: Tags processing code

[Ryan Mallon]

On 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

A few comments below.

~Ryan

> ---
>  fs/yaffs2/yaffs_packedtags1.c |   53 ++++++
>  fs/yaffs2/yaffs_packedtags1.h |   39 ++++
>  fs/yaffs2/yaffs_packedtags2.c |  187 +++++++++++++++++++
>  fs/yaffs2/yaffs_packedtags2.h |   47 +++++
>  fs/yaffs2/yaffs_tagscompat.c  |  413 +++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_tagscompat.h  |   36 ++++
>  6 files changed, 775 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_packedtags1.c
>  create mode 100644 fs/yaffs2/yaffs_packedtags1.h
>  create mode 100644 fs/yaffs2/yaffs_packedtags2.c
>  create mode 100644 fs/yaffs2/yaffs_packedtags2.h
>  create mode 100644 fs/yaffs2/yaffs_tagscompat.c
>  create mode 100644 fs/yaffs2/yaffs_tagscompat.h
> 
> diff --git a/fs/yaffs2/yaffs_packedtags1.c b/fs/yaffs2/yaffs_packedtags1.c
> new file mode 100644
> index 0000000..873f065
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_packedtags1.c
> @@ -0,0 +1,53 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_packedtags1.h"
> +#include "yportenv.h"
> +
> +void yaffs_pack_tags1(struct yaffs_packed_tags1 *pt,
> +		      const struct yaffs_ext_tags *t)
> +{
> +	pt->chunk_id = t->chunk_id;
> +	pt->serial_number = t->serial_number;
> +	pt->n_bytes = t->n_bytes;
> +	pt->obj_id = t->obj_id;
> +	pt->ecc = 0;
> +	pt->deleted = (t->is_deleted) ? 0 : 1;
> +	pt->unused_stuff = 0;
> +	pt->should_be_ff = 0xFFFFFFFF;
> +}
> +
> +void yaffs_unpack_tags1(struct yaffs_ext_tags *t,
> +			const struct yaffs_packed_tags1 *pt)
> +{
> +	static const u8 all_ff[12] = {
> +		0xff, 0xff, 0xff, 0xff,
> +		0xff, 0xff, 0xff, 0xff,
> +		0xff, 0xff, 0xff, 0xff
> +	};
> +
> +	if (memcmp(all_ff, pt, sizeof(struct yaffs_packed_tags1))) {
> +		t->block_bad = 0;
> +		if (pt->should_be_ff != 0xFFFFFFFF)

You have a combination of upper and lower letters for hex constants. You
should pick one and be consistent.

> +			t->block_bad = 1;
> +		t->chunk_used = 1;
> +		t->obj_id = pt->obj_id;
> +		t->chunk_id = pt->chunk_id;
> +		t->n_bytes = pt->n_bytes;
> +		t->ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
> +		t->is_deleted = (pt->deleted) ? 0 : 1;
> +		t->serial_number = pt->serial_number;
> +	} else {
> +		memset(t, 0, sizeof(struct yaffs_ext_tags));
> +	}
> +}
> diff --git a/fs/yaffs2/yaffs_packedtags1.h b/fs/yaffs2/yaffs_packedtags1.h
> new file mode 100644
> index 0000000..d6861ff
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_packedtags1.h
> @@ -0,0 +1,39 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +/* This is used to pack YAFFS1 tags, not YAFFS2 tags. */
> +
> +#ifndef __YAFFS_PACKEDTAGS1_H__
> +#define __YAFFS_PACKEDTAGS1_H__
> +
> +#include "yaffs_guts.h"
> +
> +struct yaffs_packed_tags1 {
> +	unsigned chunk_id:20;
> +	unsigned serial_number:2;
> +	unsigned n_bytes:10;
> +	unsigned obj_id:18;
> +	unsigned ecc:12;
> +	unsigned deleted:1;
> +	unsigned unused_stuff:1;
> +	unsigned should_be_ff;
> +
> +};
> +
> +void yaffs_pack_tags1(struct yaffs_packed_tags1 *pt,
> +		      const struct yaffs_ext_tags *t);
> +void yaffs_unpack_tags1(struct yaffs_ext_tags *t,
> +			const struct yaffs_packed_tags1 *pt);
> +#endif
> diff --git a/fs/yaffs2/yaffs_packedtags2.c b/fs/yaffs2/yaffs_packedtags2.c
> new file mode 100644
> index 0000000..2bb31b0
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_packedtags2.c
> @@ -0,0 +1,187 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_packedtags2.h"
> +#include "yportenv.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_tagsvalidity.h"
> +
> +/* This code packs a set of extended tags into a binary structure for
> + * NAND storage
> + */
> +
> +/* Some of the information is "extra" struff which can be packed in to
> + * speed scanning
> + * This is defined by having the EXTRA_HEADER_INFO_FLAG set.
> + */
> +
> +/* Extra flags applied to chunk_id */
> +
> +#define EXTRA_HEADER_INFO_FLAG	0x80000000
> +#define EXTRA_SHRINK_FLAG	0x40000000
> +#define EXTRA_SHADOWS_FLAG	0x20000000
> +#define EXTRA_SPARE_FLAGS	0x10000000
> +
> +#define ALL_EXTRA_FLAGS		0xF0000000
> +
> +/* Also, the top 4 bits of the object Id are set to the object type. */
> +#define EXTRA_OBJECT_TYPE_SHIFT (28)
> +#define EXTRA_OBJECT_TYPE_MASK  ((0x0F) << EXTRA_OBJECT_TYPE_SHIFT)
> +
> +static void yaffs_dump_packed_tags2_tags_only(
> +				const struct yaffs_packed_tags2_tags_only *ptt)
> +{
> +	yaffs_trace(YAFFS_TRACE_MTD,
> +		"packed tags obj %d chunk %d byte %d seq %d",
> +		ptt->obj_id, ptt->chunk_id, ptt->n_bytes, ptt->seq_number);
> +}
> +
> +static void yaffs_dump_packed_tags2(const struct yaffs_packed_tags2 *pt)
> +{
> +	yaffs_dump_packed_tags2_tags_only(&pt->t);
> +}
> +
> +static void yaffs_dump_tags2(const struct yaffs_ext_tags *t)
> +{
> +	yaffs_trace(YAFFS_TRACE_MTD,
> +		"ext.tags eccres %d blkbad %d chused %d obj %d chunk%d byte %d del %d ser %d seq %d",
> +		t->ecc_result, t->block_bad, t->chunk_used, t->obj_id,
> +		t->chunk_id, t->n_bytes, t->is_deleted, t->serial_number,
> +		t->seq_number);
> +
> +}
> +
> +void yaffs_pack_tags2_tags_only(struct yaffs_packed_tags2_tags_only *ptt,
> +				const struct yaffs_ext_tags *t)
> +{
> +	ptt->chunk_id = t->chunk_id;
> +	ptt->seq_number = t->seq_number;
> +	ptt->n_bytes = t->n_bytes;
> +	ptt->obj_id = t->obj_id;
> +
> +	if (t->chunk_id == 0 && t->extra_available) {
> +		/* Store the extra header info instead */
> +		/* We save the parent object in the chunk_id */
> +		ptt->chunk_id = EXTRA_HEADER_INFO_FLAG | t->extra_parent_id;
> +		if (t->extra_is_shrink)
> +			ptt->chunk_id |= EXTRA_SHRINK_FLAG;
> +		if (t->extra_shadows)
> +			ptt->chunk_id |= EXTRA_SHADOWS_FLAG;
> +
> +		ptt->obj_id &= ~EXTRA_OBJECT_TYPE_MASK;
> +		ptt->obj_id |= (t->extra_obj_type << EXTRA_OBJECT_TYPE_SHIFT);
> +
> +		if (t->extra_obj_type == YAFFS_OBJECT_TYPE_HARDLINK)
> +			ptt->n_bytes = t->extra_equiv_id;
> +		else if (t->extra_obj_type == YAFFS_OBJECT_TYPE_FILE)
> +			ptt->n_bytes = t->extra_length;
> +		else
> +			ptt->n_bytes = 0;
> +	}
> +
> +	yaffs_dump_packed_tags2_tags_only(ptt);
> +	yaffs_dump_tags2(t);
> +}
> +
> +void yaffs_pack_tags2(struct yaffs_packed_tags2 *pt,
> +		      const struct yaffs_ext_tags *t, int tags_ecc)
> +{
> +	yaffs_pack_tags2_tags_only(&pt->t, t);
> +
> +	if (tags_ecc)
> +		yaffs_ecc_calc_other((unsigned char *)&pt->t,
> +				     sizeof(struct
> +					    yaffs_packed_tags2_tags_only),
> +				     &pt->ecc);
> +}
> +
> +void yaffs_unpack_tags2_tags_only(struct yaffs_ext_tags *t,
> +				  struct yaffs_packed_tags2_tags_only *ptt)
> +{
> +	memset(t, 0, sizeof(struct yaffs_ext_tags));
> +	yaffs_init_tags(t);
> +
> +	if (ptt->seq_number != 0xFFFFFFFF) {
> +		t->block_bad = 0;
> +		t->chunk_used = 1;
> +		t->obj_id = ptt->obj_id;
> +		t->chunk_id = ptt->chunk_id;
> +		t->n_bytes = ptt->n_bytes;
> +		t->is_deleted = 0;
> +		t->serial_number = 0;
> +		t->seq_number = ptt->seq_number;
> +
> +		/* Do extra header info stuff */
> +		if (ptt->chunk_id & EXTRA_HEADER_INFO_FLAG) {
> +			t->chunk_id = 0;
> +			t->n_bytes = 0;
> +
> +			t->extra_available = 1;
> +			t->extra_parent_id =
> +			    ptt->chunk_id & (~(ALL_EXTRA_FLAGS));
> +			t->extra_is_shrink =
> +			    (ptt->chunk_id & EXTRA_SHRINK_FLAG) ? 1 : 0;
> +			t->extra_shadows =
> +			    (ptt->chunk_id & EXTRA_SHADOWS_FLAG) ? 1 : 0;
> +			t->extra_obj_type =
> +			    ptt->obj_id >> EXTRA_OBJECT_TYPE_SHIFT;
> +			t->obj_id &= ~EXTRA_OBJECT_TYPE_MASK;
> +
> +			if (t->extra_obj_type == YAFFS_OBJECT_TYPE_HARDLINK)
> +				t->extra_equiv_id = ptt->n_bytes;
> +			else
> +				t->extra_length = ptt->n_bytes;
> +		}
> +	}
> +	yaffs_dump_packed_tags2_tags_only(ptt);
> +	yaffs_dump_tags2(t);
> +}
> +
> +void yaffs_unpack_tags2(struct yaffs_ext_tags *t, struct yaffs_packed_tags2 *pt,
> +			int tags_ecc)
> +{
> +	enum yaffs_ecc_result ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
> +
> +	if (pt->t.seq_number != 0xFFFFFFFF && tags_ecc) {
> +		/* Chunk is in use and we need to do ECC */
> +
> +		struct yaffs_ecc_other ecc;
> +		int result;
> +		yaffs_ecc_calc_other((unsigned char *)&pt->t,
> +				sizeof(struct yaffs_packed_tags2_tags_only),
> +				&ecc);
> +		result =
> +		    yaffs_ecc_correct_other((unsigned char *)&pt->t,
> +				sizeof(struct yaffs_packed_tags2_tags_only),
> +				&pt->ecc, &ecc);
> +		switch (result) {
> +		case 0:
> +			ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
> +			break;
> +		case 1:
> +			ecc_result = YAFFS_ECC_RESULT_FIXED;
> +			break;
> +		case -1:
> +			ecc_result = YAFFS_ECC_RESULT_UNFIXED;
> +			break;
> +		default:
> +			ecc_result = YAFFS_ECC_RESULT_UNKNOWN;
> +		}
> +	}
> +	yaffs_unpack_tags2_tags_only(t, &pt->t);
> +
> +	t->ecc_result = ecc_result;
> +
> +	yaffs_dump_packed_tags2(pt);
> +	yaffs_dump_tags2(t);
> +}
> diff --git a/fs/yaffs2/yaffs_packedtags2.h b/fs/yaffs2/yaffs_packedtags2.h
> new file mode 100644
> index 0000000..f329669
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_packedtags2.h
> @@ -0,0 +1,47 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +/* This is used to pack YAFFS2 tags, not YAFFS1tags. */
> +
> +#ifndef __YAFFS_PACKEDTAGS2_H__
> +#define __YAFFS_PACKEDTAGS2_H__
> +
> +#include "yaffs_guts.h"
> +#include "yaffs_ecc.h"
> +
> +struct yaffs_packed_tags2_tags_only {
> +	unsigned seq_number;
> +	unsigned obj_id;
> +	unsigned chunk_id;
> +	unsigned n_bytes;
> +};
> +
> +struct yaffs_packed_tags2 {
> +	struct yaffs_packed_tags2_tags_only t;
> +	struct yaffs_ecc_other ecc;
> +};
> +
> +/* Full packed tags with ECC, used for oob tags */
> +void yaffs_pack_tags2(struct yaffs_packed_tags2 *pt,
> +		      const struct yaffs_ext_tags *t, int tags_ecc);
> +void yaffs_unpack_tags2(struct yaffs_ext_tags *t, struct yaffs_packed_tags2 *pt,
> +			int tags_ecc);
> +
> +/* Only the tags part (no ECC for use with inband tags */
> +void yaffs_pack_tags2_tags_only(struct yaffs_packed_tags2_tags_only *pt,
> +				const struct yaffs_ext_tags *t);
> +void yaffs_unpack_tags2_tags_only(struct yaffs_ext_tags *t,
> +				  struct yaffs_packed_tags2_tags_only *pt);
> +#endif
> diff --git a/fs/yaffs2/yaffs_tagscompat.c b/fs/yaffs2/yaffs_tagscompat.c
> new file mode 100644
> index 0000000..35d33c9
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_tagscompat.c
> @@ -0,0 +1,413 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_guts.h"
> +#include "yaffs_tagscompat.h"
> +#include "yaffs_ecc.h"
> +#include "yaffs_getblockinfo.h"
> +#include "yaffs_trace.h"
> +
> +static void yaffs_handle_rd_data_error(struct yaffs_dev *dev, int nand_chunk);
> +
> +
> +/********** Tags ECC calculations  *********/
> +
> +void yaffs_calc_ecc(const u8 *data, struct yaffs_spare *spare)
> +{
> +	yaffs_ecc_cacl(data, spare->ecc1);
> +	yaffs_ecc_cacl(&data[256], spare->ecc2);
> +}
> +
> +void yaffs_calc_tags_ecc(struct yaffs_tags *tags)
> +{
> +	/* Calculate an ecc */
> +	unsigned char *b = ((union yaffs_tags_union *)tags)->as_bytes;
> +	unsigned i, j;
> +	unsigned ecc = 0;
> +	unsigned bit = 0;
> +
> +	tags->ecc = 0;
> +
> +	for (i = 0; i < 8; i++) {
> +		for (j = 1; j & 0xff; j <<= 1) {
> +			bit++;
> +			if (b[i] & j)
> +				ecc ^= bit;
> +		}
> +	}
> +	tags->ecc = ecc;
> +}
> +
> +int yaffs_check_tags_ecc(struct yaffs_tags *tags)
> +{
> +	unsigned ecc = tags->ecc;
> +
> +	yaffs_calc_tags_ecc(tags);
> +
> +	ecc ^= tags->ecc;
> +
> +	if (ecc && ecc <= 64) {
> +		/* TODO: Handle the failure better. Retire? */
> +		unsigned char *b = ((union yaffs_tags_union *)tags)->as_bytes;
> +
> +		ecc--;
> +
> +		b[ecc / 8] ^= (1 << (ecc & 7));
> +
> +		/* Now recvalc the ecc */
> +		yaffs_calc_tags_ecc(tags);
> +
> +		return 1;	/* recovered error */
> +	} else if (ecc) {
> +		/* Wierd ecc failure value */
> +		/* TODO Need to do somethiong here */

Maybe print a warning at least?

> +		return -1;	/* unrecovered error */
> +	}
> +	return 0;
> +}
> +
> +/********** Tags **********/
> +
> +static void yaffs_load_tags_to_spare(struct yaffs_spare *spare_ptr,
> +				     struct yaffs_tags *tags_ptr)
> +{
> +	union yaffs_tags_union *tu = (union yaffs_tags_union *)tags_ptr;
> +
> +	yaffs_calc_tags_ecc(tags_ptr);
> +
> +	spare_ptr->tb0 = tu->as_bytes[0];
> +	spare_ptr->tb1 = tu->as_bytes[1];
> +	spare_ptr->tb2 = tu->as_bytes[2];
> +	spare_ptr->tb3 = tu->as_bytes[3];
> +	spare_ptr->tb4 = tu->as_bytes[4];
> +	spare_ptr->tb5 = tu->as_bytes[5];
> +	spare_ptr->tb6 = tu->as_bytes[6];
> +	spare_ptr->tb7 = tu->as_bytes[7];
> +}
> +
> +static void yaffs_get_tags_from_spare(struct yaffs_dev *dev,
> +				      struct yaffs_spare *spare_ptr,
> +				      struct yaffs_tags *tags_ptr)
> +{
> +	union yaffs_tags_union *tu = (union yaffs_tags_union *)tags_ptr;
> +	int result;
> +
> +	tu->as_bytes[0] = spare_ptr->tb0;
> +	tu->as_bytes[1] = spare_ptr->tb1;
> +	tu->as_bytes[2] = spare_ptr->tb2;
> +	tu->as_bytes[3] = spare_ptr->tb3;
> +	tu->as_bytes[4] = spare_ptr->tb4;
> +	tu->as_bytes[5] = spare_ptr->tb5;
> +	tu->as_bytes[6] = spare_ptr->tb6;
> +	tu->as_bytes[7] = spare_ptr->tb7;
> +
> +	result = yaffs_check_tags_ecc(tags_ptr);
> +	if (result > 0)
> +		dev->n_tags_ecc_fixed++;
> +	else if (result < 0)
> +		dev->n_tags_ecc_unfixed++;
> +}
> +
> +static void yaffs_spare_init(struct yaffs_spare *spare)
> +{
> +	memset(spare, 0xFF, sizeof(struct yaffs_spare));
> +}

This could be replaced by having a global:

static const struct yaffs_spare_ff = {
	.tb0	= 0xff;
	.tb1	= 0xff;
	...
};

> +
> +static int yaffs_wr_nand(struct yaffs_dev *dev,
> +			 int nand_chunk, const u8 *data,
> +			 struct yaffs_spare *spare)
> +{
> +	if (nand_chunk < dev->param.start_block * dev->param.chunks_per_block) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"**>> yaffs chunk %d is not valid",
> +			nand_chunk);
> +		return YAFFS_FAIL;
> +	}
> +
> +	return dev->param.write_chunk_fn(dev, nand_chunk, data, spare);
> +}
> +
> +static int yaffs_rd_chunk_nand(struct yaffs_dev *dev,
> +			       int nand_chunk,
> +			       u8 *data,
> +			       struct yaffs_spare *spare,
> +			       enum yaffs_ecc_result *ecc_result,
> +			       int correct_errors)
> +{
> +	int ret_val;
> +	struct yaffs_spare local_spare;
> +
> +	if (!spare) {
> +		/* If we don't have a real spare, then we use a local one. */
> +		/* Need this for the calculation of the ecc */
> +		spare = &local_spare;

Is this safe? Can we get left pointing at something which isn't there
anymore?

> +	}
> +
> +	if (!dev->param.use_nand_ecc) {
> +		ret_val =
> +		    dev->param.read_chunk_fn(dev, nand_chunk, data, spare);
> +		if (data && correct_errors) {
> +			/* Do ECC correction */
> +			/* Todo handle any errors */
> +			int ecc_result1, ecc_result2;
> +			u8 calc_ecc[3];
> +
> +			yaffs_ecc_cacl(data, calc_ecc);
> +			ecc_result1 =
> +			    yaffs_ecc_correct(data, spare->ecc1, calc_ecc);
> +			yaffs_ecc_cacl(&data[256], calc_ecc);
> +			ecc_result2 =
> +			    yaffs_ecc_correct(&data[256], spare->ecc2,
> +					      calc_ecc);
> +
> +			if (ecc_result1 > 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>yaffs ecc error fix performed on chunk %d:0",
> +					nand_chunk);
> +				dev->n_ecc_fixed++;
> +			} else if (ecc_result1 < 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>yaffs ecc error unfixed on chunk %d:0",
> +					nand_chunk);
> +				dev->n_ecc_unfixed++;
> +			}
> +
> +			if (ecc_result2 > 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>yaffs ecc error fix performed on chunk %d:1",
> +					nand_chunk);
> +				dev->n_ecc_fixed++;
> +			} else if (ecc_result2 < 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>yaffs ecc error unfixed on chunk %d:1",
> +					nand_chunk);
> +				dev->n_ecc_unfixed++;
> +			}
> +
> +			if (ecc_result1 || ecc_result2) {
> +				/* We had a data problem on this page */
> +				yaffs_handle_rd_data_error(dev, nand_chunk);
> +			}
> +
> +			if (ecc_result1 < 0 || ecc_result2 < 0)
> +				*ecc_result = YAFFS_ECC_RESULT_UNFIXED;
> +			else if (ecc_result1 > 0 || ecc_result2 > 0)
> +				*ecc_result = YAFFS_ECC_RESULT_FIXED;
> +			else
> +				*ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
> +		}
> +	} else {
> +		/* Must allocate enough memory for spare+2*sizeof(int) */
> +		/* for ecc results from device. */
> +		struct yaffs_nand_spare nspare;
> +
> +		memset(&nspare, 0, sizeof(nspare));
> +
> +		ret_val = dev->param.read_chunk_fn(dev, nand_chunk, data,
> +						   (struct yaffs_spare *)
> +						   &nspare);
> +		memcpy(spare, &nspare, sizeof(struct yaffs_spare));
> +		if (data && correct_errors) {
> +			if (nspare.eccres1 > 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>mtd ecc error fix performed on chunk %d:0",
> +					nand_chunk);
> +			} else if (nspare.eccres1 < 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>mtd ecc error unfixed on chunk %d:0",
> +					nand_chunk);
> +			}
> +
> +			if (nspare.eccres2 > 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>mtd ecc error fix performed on chunk %d:1",
> +					nand_chunk);
> +			} else if (nspare.eccres2 < 0) {
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"**>>mtd ecc error unfixed on chunk %d:1",
> +					nand_chunk);
> +			}
> +
> +			if (nspare.eccres1 || nspare.eccres2) {
> +				/* We had a data problem on this page */
> +				yaffs_handle_rd_data_error(dev, nand_chunk);
> +			}
> +
> +			if (nspare.eccres1 < 0 || nspare.eccres2 < 0)
> +				*ecc_result = YAFFS_ECC_RESULT_UNFIXED;
> +			else if (nspare.eccres1 > 0 || nspare.eccres2 > 0)
> +				*ecc_result = YAFFS_ECC_RESULT_FIXED;
> +			else
> +				*ecc_result = YAFFS_ECC_RESULT_NO_ERROR;
> +
> +		}
> +	}
> +	return ret_val;
> +}
> +
> +/*
> + * Functions for robustisizing
> + */
> +
> +static void yaffs_handle_rd_data_error(struct yaffs_dev *dev, int nand_chunk)
> +{
> +	int flash_block = nand_chunk / dev->param.chunks_per_block;
> +
> +	/* Mark the block for retirement */
> +	yaffs_get_block_info(dev, flash_block + dev->block_offset)->
> +		needs_retiring = 1;
> +	yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
> +		"**>>Block %d marked for retirement",
> +		flash_block);
> +
> +	/* TODO:
> +	 * Just do a garbage collection on the affected block
> +	 * then retire the block
> +	 * NB recursion
> +	 */
> +}
> +
> +int yaffs_tags_compat_wr(struct yaffs_dev *dev,
> +			 int nand_chunk,
> +			 const u8 *data, const struct yaffs_ext_tags *ext_tags)
> +{
> +	struct yaffs_spare spare;
> +	struct yaffs_tags tags;
> +
> +	yaffs_spare_init(&spare);
> +
> +	if (ext_tags->is_deleted)
> +		spare.page_status = 0;
> +	else {
> +		tags.obj_id = ext_tags->obj_id;
> +		tags.chunk_id = ext_tags->chunk_id;
> +
> +		tags.n_bytes_lsb = ext_tags->n_bytes & 0x3ff;
> +
> +		if (dev->data_bytes_per_chunk >= 1024)
> +			tags.n_bytes_msb = (ext_tags->n_bytes >> 10) & 3;
> +		else
> +			tags.n_bytes_msb = 3;
> +
> +		tags.serial_number = ext_tags->serial_number;
> +
> +		if (!dev->param.use_nand_ecc && data)
> +			yaffs_calc_ecc(data, &spare);
> +
> +		yaffs_load_tags_to_spare(&spare, &tags);
> +
> +	}
> +
> +	return yaffs_wr_nand(dev, nand_chunk, data, &spare);
> +}
> +
> +int yaffs_tags_compat_rd(struct yaffs_dev *dev,
> +			 int nand_chunk,
> +			 u8 *data, struct yaffs_ext_tags *ext_tags)
> +{
> +	struct yaffs_spare spare;
> +	struct yaffs_tags tags;
> +	enum yaffs_ecc_result ecc_result = YAFFS_ECC_RESULT_UNKNOWN;
> +	static struct yaffs_spare spare_ff;
> +	static int init;
> +
> +	if (!init) {
> +		memset(&spare_ff, 0xFF, sizeof(spare_ff));
> +		init = 1;

Don't do this. Just have a const initialised struct.

> +	}
> +
> +	if (yaffs_rd_chunk_nand(dev, nand_chunk,
> +					data, &spare, &ecc_result, 1)) {
> +		/* ext_tags may be NULL */
> +		if (ext_tags) {
> +
> +			int deleted =
> +			    (hweight8(spare.page_status) < 7) ? 1 : 0;
> +
> +			ext_tags->is_deleted = deleted;
> +			ext_tags->ecc_result = ecc_result;
> +			ext_tags->block_bad = 0;	/* We're reading it */
> +			/* therefore it is not a bad block */
> +			ext_tags->chunk_used =
> +			    (memcmp(&spare_ff, &spare, sizeof(spare_ff)) !=
> +			     0) ? 1 : 0;
> +
> +			if (ext_tags->chunk_used) {
> +				yaffs_get_tags_from_spare(dev, &spare, &tags);
> +
> +				ext_tags->obj_id = tags.obj_id;
> +				ext_tags->chunk_id = tags.chunk_id;
> +				ext_tags->n_bytes = tags.n_bytes_lsb;
> +
> +				if (dev->data_bytes_per_chunk >= 1024)
> +					ext_tags->n_bytes |=
> +					    (((unsigned)tags.
> +					      n_bytes_msb) << 10);
> +
> +				ext_tags->serial_number = tags.serial_number;
> +			}
> +		}
> +
> +		return YAFFS_OK;
> +	} else {
> +		return YAFFS_FAIL;
> +	}
> +}
> +
> +int yaffs_tags_compat_mark_bad(struct yaffs_dev *dev, int flash_block)
> +{
> +	struct yaffs_spare spare;
> +
> +	memset(&spare, 0xff, sizeof(struct yaffs_spare));
> +
> +	spare.block_status = 'Y';
> +
> +	yaffs_wr_nand(dev, flash_block * dev->param.chunks_per_block, NULL,
> +		      &spare);
> +	yaffs_wr_nand(dev, flash_block * dev->param.chunks_per_block + 1,
> +		      NULL, &spare);
> +
> +	return YAFFS_OK;
> +}
> +
> +int yaffs_tags_compat_query_block(struct yaffs_dev *dev,
> +				  int block_no,
> +				  enum yaffs_block_state *state,
> +				  u32 *seq_number)
> +{
> +	struct yaffs_spare spare0, spare1;
> +	static struct yaffs_spare spare_ff;
> +	static int init;
> +	enum yaffs_ecc_result dummy;
> +
> +	if (!init) {
> +		memset(&spare_ff, 0xFF, sizeof(spare_ff));
> +		init = 1;
> +	}
> +
> +	*seq_number = 0;
> +
> +	yaffs_rd_chunk_nand(dev, block_no * dev->param.chunks_per_block, NULL,
> +			    &spare0, &dummy, 1);
> +	yaffs_rd_chunk_nand(dev, block_no * dev->param.chunks_per_block + 1,
> +			    NULL, &spare1, &dummy, 1);
> +
> +	if (hweight8(spare0.block_status & spare1.block_status) < 7)
> +		*state = YAFFS_BLOCK_STATE_DEAD;
> +	else if (memcmp(&spare_ff, &spare0, sizeof(spare_ff)) == 0)
> +		*state = YAFFS_BLOCK_STATE_EMPTY;
> +	else
> +		*state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
> +
> +	return YAFFS_OK;
> +}
> diff --git a/fs/yaffs2/yaffs_tagscompat.h b/fs/yaffs2/yaffs_tagscompat.h
> new file mode 100644
> index 0000000..ae15e0b
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_tagscompat.h
> @@ -0,0 +1,36 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_TAGSCOMPAT_H__
> +#define __YAFFS_TAGSCOMPAT_H__
> +
> +#include "yaffs_guts.h"
> +int yaffs_tags_compat_wr(struct yaffs_dev *dev,
> +			 int nand_chunk,
> +			 const u8 *data, const struct yaffs_ext_tags *tags);
> +int yaffs_tags_compat_rd(struct yaffs_dev *dev,
> +			 int nand_chunk,
> +			 u8 *data, struct yaffs_ext_tags *tags);
> +int yaffs_tags_compat_mark_bad(struct yaffs_dev *dev, int block_no);
> +int yaffs_tags_compat_query_block(struct yaffs_dev *dev,
> +				  int block_no,
> +				  enum yaffs_block_state *state,
> +				  u32 *seq_number);
> +
> +void yaffs_calc_tags_ecc(struct yaffs_tags *tags);
> +int yaffs_check_tags_ecc(struct yaffs_tags *tags);
> +int yaffs_count_bits(u8 byte);
> +
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 06/10] Add yaffs2 file system: Tracing and verification code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_tagsvalidity.c |   26 ++
 fs/yaffs2/yaffs_tagsvalidity.h |   23 ++
 fs/yaffs2/yaffs_trace.h        |   57 +++++
 fs/yaffs2/yaffs_verify.c       |  524 ++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_verify.h       |   43 ++++
 5 files changed, 673 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_tagsvalidity.c
 create mode 100644 fs/yaffs2/yaffs_tagsvalidity.h
 create mode 100644 fs/yaffs2/yaffs_trace.h
 create mode 100644 fs/yaffs2/yaffs_verify.c
 create mode 100644 fs/yaffs2/yaffs_verify.h

diff --git a/fs/yaffs2/yaffs_tagsvalidity.c b/fs/yaffs2/yaffs_tagsvalidity.c
new file mode 100644
index 0000000..582f36a
--- /dev/null
+++ b/fs/yaffs2/yaffs_tagsvalidity.c
@@ -0,0 +1,26 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_tagsvalidity.h"
+
+void yaffs_init_tags(struct yaffs_ext_tags *tags)
+{
+	memset(tags, 0, sizeof(struct yaffs_ext_tags));
+	tags->validity0 = 0xAAAAAAAA;
+	tags->validity1 = 0x55555555;
+}
+
+int yaffs_validate_tags(struct yaffs_ext_tags *tags)
+{
+	return (tags->validity0 == 0xAAAAAAAA && tags->validity1 == 0x55555555);
+}
diff --git a/fs/yaffs2/yaffs_tagsvalidity.h b/fs/yaffs2/yaffs_tagsvalidity.h
new file mode 100644
index 0000000..36a021f
--- /dev/null
+++ b/fs/yaffs2/yaffs_tagsvalidity.h
@@ -0,0 +1,23 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_TAGS_VALIDITY_H__
+#define __YAFFS_TAGS_VALIDITY_H__
+
+#include "yaffs_guts.h"
+
+void yaffs_init_tags(struct yaffs_ext_tags *tags);
+int yaffs_validate_tags(struct yaffs_ext_tags *tags);
+#endif
diff --git a/fs/yaffs2/yaffs_trace.h b/fs/yaffs2/yaffs_trace.h
new file mode 100644
index 0000000..6273dbf
--- /dev/null
+++ b/fs/yaffs2/yaffs_trace.h
@@ -0,0 +1,57 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YTRACE_H__
+#define __YTRACE_H__
+
+extern unsigned int yaffs_trace_mask;
+extern unsigned int yaffs_wr_attempts;
+
+/*
+ * Tracing flags.
+ * The flags masked in YAFFS_TRACE_ALWAYS are always traced.
+ */
+
+#define YAFFS_TRACE_OS			0x00000002
+#define YAFFS_TRACE_ALLOCATE		0x00000004
+#define YAFFS_TRACE_SCAN		0x00000008
+#define YAFFS_TRACE_BAD_BLOCKS		0x00000010
+#define YAFFS_TRACE_ERASE		0x00000020
+#define YAFFS_TRACE_GC			0x00000040
+#define YAFFS_TRACE_WRITE		0x00000080
+#define YAFFS_TRACE_TRACING		0x00000100
+#define YAFFS_TRACE_DELETION		0x00000200
+#define YAFFS_TRACE_BUFFERS		0x00000400
+#define YAFFS_TRACE_NANDACCESS		0x00000800
+#define YAFFS_TRACE_GC_DETAIL		0x00001000
+#define YAFFS_TRACE_SCAN_DEBUG		0x00002000
+#define YAFFS_TRACE_MTD			0x00004000
+#define YAFFS_TRACE_CHECKPOINT		0x00008000
+
+#define YAFFS_TRACE_VERIFY		0x00010000
+#define YAFFS_TRACE_VERIFY_NAND		0x00020000
+#define YAFFS_TRACE_VERIFY_FULL		0x00040000
+#define YAFFS_TRACE_VERIFY_ALL		0x000F0000
+
+#define YAFFS_TRACE_SYNC		0x00100000
+#define YAFFS_TRACE_BACKGROUND		0x00200000
+#define YAFFS_TRACE_LOCK		0x00400000
+#define YAFFS_TRACE_MOUNT		0x00800000
+
+#define YAFFS_TRACE_ERROR		0x40000000
+#define YAFFS_TRACE_BUG			0x80000000
+#define YAFFS_TRACE_ALWAYS		0xF0000000
+
+#endif
diff --git a/fs/yaffs2/yaffs_verify.c b/fs/yaffs2/yaffs_verify.c
new file mode 100644
index 0000000..1a5ed9a
--- /dev/null
+++ b/fs/yaffs2/yaffs_verify.c
@@ -0,0 +1,524 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_verify.h"
+#include "yaffs_trace.h"
+#include "yaffs_bitmap.h"
+#include "yaffs_getblockinfo.h"
+#include "yaffs_nand.h"
+
+int yaffs_skip_verification(struct yaffs_dev *dev)
+{
+	dev = dev;
+	return !(yaffs_trace_mask &
+		 (YAFFS_TRACE_VERIFY | YAFFS_TRACE_VERIFY_FULL));
+}
+
+static int yaffs_skip_full_verification(struct yaffs_dev *dev)
+{
+	dev = dev;
+	return !(yaffs_trace_mask & (YAFFS_TRACE_VERIFY_FULL));
+}
+
+static int yaffs_skip_nand_verification(struct yaffs_dev *dev)
+{
+	dev = dev;
+	return !(yaffs_trace_mask & (YAFFS_TRACE_VERIFY_NAND));
+}
+
+static const char * const block_state_name[] = {
+	"Unknown",
+	"Needs scanning",
+	"Scanning",
+	"Empty",
+	"Allocating",
+	"Full",
+	"Dirty",
+	"Checkpoint",
+	"Collecting",
+	"Dead"
+};
+
+void yaffs_verify_blk(struct yaffs_dev *dev, struct yaffs_block_info *bi, int n)
+{
+	int actually_used;
+	int in_use;
+
+	if (yaffs_skip_verification(dev))
+		return;
+
+	/* Report illegal runtime states */
+	if (bi->block_state >= YAFFS_NUMBER_OF_BLOCK_STATES)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Block %d has undefined state %d",
+			n, bi->block_state);
+
+	switch (bi->block_state) {
+	case YAFFS_BLOCK_STATE_UNKNOWN:
+	case YAFFS_BLOCK_STATE_SCANNING:
+	case YAFFS_BLOCK_STATE_NEEDS_SCANNING:
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Block %d has bad run-state %s",
+			n, block_state_name[bi->block_state]);
+	}
+
+	/* Check pages in use and soft deletions are legal */
+
+	actually_used = bi->pages_in_use - bi->soft_del_pages;
+
+	if (bi->pages_in_use < 0
+	    || bi->pages_in_use > dev->param.chunks_per_block
+	    || bi->soft_del_pages < 0
+	    || bi->soft_del_pages > dev->param.chunks_per_block
+	    || actually_used < 0 || actually_used > dev->param.chunks_per_block)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Block %d has illegal values pages_in_used %d soft_del_pages %d",
+			n, bi->pages_in_use, bi->soft_del_pages);
+
+	/* Check chunk bitmap legal */
+	in_use = yaffs_count_chunk_bits(dev, n);
+	if (in_use != bi->pages_in_use)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Block %d has inconsistent values pages_in_use %d counted chunk bits %d",
+			n, bi->pages_in_use, in_use);
+}
+
+void yaffs_verify_collected_blk(struct yaffs_dev *dev,
+				struct yaffs_block_info *bi, int n)
+{
+	yaffs_verify_blk(dev, bi, n);
+
+	/* After collection the block should be in the erased state */
+
+	if (bi->block_state != YAFFS_BLOCK_STATE_COLLECTING &&
+	    bi->block_state != YAFFS_BLOCK_STATE_EMPTY) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"Block %d is in state %d after gc, should be erased",
+			n, bi->block_state);
+	}
+}
+
+void yaffs_verify_blocks(struct yaffs_dev *dev)
+{
+	int i;
+	int state_count[YAFFS_NUMBER_OF_BLOCK_STATES];
+	int illegal_states = 0;
+
+	if (yaffs_skip_verification(dev))
+		return;
+
+	memset(state_count, 0, sizeof(state_count));
+
+	for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
+		struct yaffs_block_info *bi = yaffs_get_block_info(dev, i);
+		yaffs_verify_blk(dev, bi, i);
+
+		if (bi->block_state < YAFFS_NUMBER_OF_BLOCK_STATES)
+			state_count[bi->block_state]++;
+		else
+			illegal_states++;
+	}
+
+	yaffs_trace(YAFFS_TRACE_VERIFY,	"Block summary");
+
+	yaffs_trace(YAFFS_TRACE_VERIFY,
+		"%d blocks have illegal states",
+		illegal_states);
+	if (state_count[YAFFS_BLOCK_STATE_ALLOCATING] > 1)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Too many allocating blocks");
+
+	for (i = 0; i < YAFFS_NUMBER_OF_BLOCK_STATES; i++)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"%s %d blocks",
+			block_state_name[i], state_count[i]);
+
+	if (dev->blocks_in_checkpt != state_count[YAFFS_BLOCK_STATE_CHECKPOINT])
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Checkpoint block count wrong dev %d count %d",
+			dev->blocks_in_checkpt,
+			state_count[YAFFS_BLOCK_STATE_CHECKPOINT]);
+
+	if (dev->n_erased_blocks != state_count[YAFFS_BLOCK_STATE_EMPTY])
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Erased block count wrong dev %d count %d",
+			dev->n_erased_blocks,
+			state_count[YAFFS_BLOCK_STATE_EMPTY]);
+
+	if (state_count[YAFFS_BLOCK_STATE_COLLECTING] > 1)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Too many collecting blocks %d (max is 1)",
+			state_count[YAFFS_BLOCK_STATE_COLLECTING]);
+}
+
+/*
+ * Verify the object header. oh must be valid, but obj and tags may be NULL in
+ * which case those tests will not be performed.
+ */
+void yaffs_verify_oh(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh,
+		     struct yaffs_ext_tags *tags, int parent_check)
+{
+	if (obj && yaffs_skip_verification(obj->my_dev))
+		return;
+
+	if (!(tags && obj && oh)) {
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Verifying object header tags %p obj %p oh %p",
+			tags, obj, oh);
+		return;
+	}
+
+	if (oh->type <= YAFFS_OBJECT_TYPE_UNKNOWN ||
+	    oh->type > YAFFS_OBJECT_TYPE_MAX)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d header type is illegal value 0x%x",
+			tags->obj_id, oh->type);
+
+	if (tags->obj_id != obj->obj_id)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d header mismatch obj_id %d",
+			tags->obj_id, obj->obj_id);
+
+	/*
+	 * Check that the object's parent ids match if parent_check requested.
+	 *
+	 * Tests do not apply to the root object.
+	 */
+
+	if (parent_check && tags->obj_id > 1 && !obj->parent)
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d header mismatch parent_id %d obj->parent is NULL",
+			tags->obj_id, oh->parent_obj_id);
+
+	if (parent_check && obj->parent &&
+	    oh->parent_obj_id != obj->parent->obj_id &&
+	    (oh->parent_obj_id != YAFFS_OBJECTID_UNLINKED ||
+	     obj->parent->obj_id != YAFFS_OBJECTID_DELETED))
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d header mismatch parent_id %d parent_obj_id %d",
+			tags->obj_id, oh->parent_obj_id,
+			obj->parent->obj_id);
+
+	if (tags->obj_id > 1 && oh->name[0] == 0)	/* Null name */
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d header name is NULL",
+			obj->obj_id);
+
+	if (tags->obj_id > 1 && ((u8) (oh->name[0])) == 0xff)	/* Junk name */
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d header name is 0xFF",
+			obj->obj_id);
+}
+
+void yaffs_verify_file(struct yaffs_obj *obj)
+{
+	int required_depth;
+	int actual_depth;
+	u32 last_chunk;
+	u32 x;
+	u32 i;
+	struct yaffs_dev *dev;
+	struct yaffs_ext_tags tags;
+	struct yaffs_tnode *tn;
+	u32 obj_id;
+
+	if (!obj)
+		return;
+
+	if (yaffs_skip_verification(obj->my_dev))
+		return;
+
+	dev = obj->my_dev;
+	obj_id = obj->obj_id;
+
+	/* Check file size is consistent with tnode depth */
+	last_chunk =
+	    obj->variant.file_variant.file_size / dev->data_bytes_per_chunk + 1;
+	x = last_chunk >> YAFFS_TNODES_LEVEL0_BITS;
+	required_depth = 0;
+	while (x > 0) {
+		x >>= YAFFS_TNODES_INTERNAL_BITS;
+		required_depth++;
+	}
+
+	actual_depth = obj->variant.file_variant.top_level;
+
+	/* Check that the chunks in the tnode tree are all correct.
+	 * We do this by scanning through the tnode tree and
+	 * checking the tags for every chunk match.
+	 */
+
+	if (yaffs_skip_nand_verification(dev))
+		return;
+
+	for (i = 1; i <= last_chunk; i++) {
+		tn = yaffs_find_tnode_0(dev, &obj->variant.file_variant, i);
+
+		if (tn) {
+			u32 the_chunk = yaffs_get_group_base(dev, tn, i);
+			if (the_chunk > 0) {
+				yaffs_rd_chunk_tags_nand(dev, the_chunk, NULL,
+							 &tags);
+				if (tags.obj_id != obj_id || tags.chunk_id != i)
+					yaffs_trace(YAFFS_TRACE_VERIFY,
+						"Object %d chunk_id %d NAND mismatch chunk %d tags (%d:%d)",
+						obj_id, i, the_chunk,
+						tags.obj_id, tags.chunk_id);
+			}
+		}
+	}
+}
+
+void yaffs_verify_link(struct yaffs_obj *obj)
+{
+	if (obj && yaffs_skip_verification(obj->my_dev))
+		return;
+
+	/* Verify sane equivalent object */
+}
+
+void yaffs_verify_symlink(struct yaffs_obj *obj)
+{
+	if (obj && yaffs_skip_verification(obj->my_dev))
+		return;
+
+	/* Verify symlink string */
+}
+
+void yaffs_verify_special(struct yaffs_obj *obj)
+{
+	if (obj && yaffs_skip_verification(obj->my_dev))
+		return;
+}
+
+void yaffs_verify_obj(struct yaffs_obj *obj)
+{
+	struct yaffs_dev *dev;
+	u32 chunk_min;
+	u32 chunk_max;
+	u32 chunk_id_ok;
+	u32 chunk_in_range;
+	u32 chunk_wrongly_deleted;
+	u32 chunk_valid;
+
+	if (!obj)
+		return;
+
+	if (obj->being_created)
+		return;
+
+	dev = obj->my_dev;
+
+	if (yaffs_skip_verification(dev))
+		return;
+
+	/* Check sane object header chunk */
+
+	chunk_min = dev->internal_start_block * dev->param.chunks_per_block;
+	chunk_max =
+	    (dev->internal_end_block + 1) * dev->param.chunks_per_block - 1;
+
+	chunk_in_range = (((unsigned)(obj->hdr_chunk)) >= chunk_min &&
+			  ((unsigned)(obj->hdr_chunk)) <= chunk_max);
+	chunk_id_ok = chunk_in_range || (obj->hdr_chunk == 0);
+	chunk_valid = chunk_in_range &&
+	    yaffs_check_chunk_bit(dev,
+				  obj->hdr_chunk / dev->param.chunks_per_block,
+				  obj->hdr_chunk % dev->param.chunks_per_block);
+	chunk_wrongly_deleted = chunk_in_range && !chunk_valid;
+
+	if (!obj->fake && (!chunk_id_ok || chunk_wrongly_deleted))
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d has chunk_id %d %s %s",
+			obj->obj_id, obj->hdr_chunk,
+			chunk_id_ok ? "" : ",out of range",
+			chunk_wrongly_deleted ? ",marked as deleted" : "");
+
+	if (chunk_valid && !yaffs_skip_nand_verification(dev)) {
+		struct yaffs_ext_tags tags;
+		struct yaffs_obj_hdr *oh;
+		u8 *buffer = yaffs_get_temp_buffer(dev, __LINE__);
+
+		oh = (struct yaffs_obj_hdr *)buffer;
+
+		yaffs_rd_chunk_tags_nand(dev, obj->hdr_chunk, buffer, &tags);
+
+		yaffs_verify_oh(obj, oh, &tags, 1);
+
+		yaffs_release_temp_buffer(dev, buffer, __LINE__);
+	}
+
+	/* Verify it has a parent */
+	if (obj && !obj->fake && (!obj->parent || obj->parent->my_dev != dev)) {
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d has parent pointer %p which does not look like an object",
+			obj->obj_id, obj->parent);
+	}
+
+	/* Verify parent is a directory */
+	if (obj->parent
+	    && obj->parent->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d's parent is not a directory (type %d)",
+			obj->obj_id, obj->parent->variant_type);
+	}
+
+	switch (obj->variant_type) {
+	case YAFFS_OBJECT_TYPE_FILE:
+		yaffs_verify_file(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_SYMLINK:
+		yaffs_verify_symlink(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_DIRECTORY:
+		yaffs_verify_dir(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_HARDLINK:
+		yaffs_verify_link(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_SPECIAL:
+		yaffs_verify_special(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_UNKNOWN:
+	default:
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Obj %d has illegaltype %d",
+		   obj->obj_id, obj->variant_type);
+		break;
+	}
+}
+
+void yaffs_verify_objects(struct yaffs_dev *dev)
+{
+	struct yaffs_obj *obj;
+	int i;
+	struct list_head *lh;
+
+	if (yaffs_skip_verification(dev))
+		return;
+
+	/* Iterate through the objects in each hash entry */
+
+	for (i = 0; i < YAFFS_NOBJECT_BUCKETS; i++) {
+		list_for_each(lh, &dev->obj_bucket[i].list) {
+			obj = list_entry(lh, struct yaffs_obj, hash_link);
+			yaffs_verify_obj(obj);
+		}
+	}
+}
+
+void yaffs_verify_obj_in_dir(struct yaffs_obj *obj)
+{
+	struct list_head *lh;
+	struct yaffs_obj *list_obj;
+	int count = 0;
+
+	if (!obj) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "No object to verify");
+		YBUG();
+		return;
+	}
+
+	if (yaffs_skip_verification(obj->my_dev))
+		return;
+
+	if (!obj->parent) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "Object does not have parent");
+		YBUG();
+		return;
+	}
+
+	if (obj->parent->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "Parent is not directory");
+		YBUG();
+	}
+
+	/* Iterate through the objects in each hash entry */
+
+	list_for_each(lh, &obj->parent->variant.dir_variant.children) {
+		list_obj = list_entry(lh, struct yaffs_obj, siblings);
+		yaffs_verify_obj(list_obj);
+		if (obj == list_obj)
+			count++;
+	}
+
+	if (count != 1) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"Object in directory %d times",
+			count);
+		YBUG();
+	}
+}
+
+void yaffs_verify_dir(struct yaffs_obj *directory)
+{
+	struct list_head *lh;
+	struct yaffs_obj *list_obj;
+
+	if (!directory) {
+		YBUG();
+		return;
+	}
+
+	if (yaffs_skip_full_verification(directory->my_dev))
+		return;
+
+	if (directory->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"Directory has wrong type: %d",
+			directory->variant_type);
+		YBUG();
+	}
+
+	/* Iterate through the objects in each hash entry */
+
+	list_for_each(lh, &directory->variant.dir_variant.children) {
+		list_obj = list_entry(lh, struct yaffs_obj, siblings);
+		if (list_obj->parent != directory) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"Object in directory list has wrong parent %p",
+				list_obj->parent);
+			YBUG();
+		}
+		yaffs_verify_obj_in_dir(list_obj);
+	}
+}
+
+static int yaffs_free_verification_failures;
+
+void yaffs_verify_free_chunks(struct yaffs_dev *dev)
+{
+	int counted;
+	int difference;
+
+	if (yaffs_skip_verification(dev))
+		return;
+
+	counted = yaffs_count_free_chunks(dev);
+
+	difference = dev->n_free_chunks - counted;
+
+	if (difference) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"Freechunks verification failure %d %d %d",
+			dev->n_free_chunks, counted, difference);
+		yaffs_free_verification_failures++;
+	}
+}
+
+int yaffs_verify_file_sane(struct yaffs_obj *in)
+{
+	in = in;
+	return YAFFS_OK;
+}
+
diff --git a/fs/yaffs2/yaffs_verify.h b/fs/yaffs2/yaffs_verify.h
new file mode 100644
index 0000000..cc6f889
--- /dev/null
+++ b/fs/yaffs2/yaffs_verify.h
@@ -0,0 +1,43 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_VERIFY_H__
+#define __YAFFS_VERIFY_H__
+
+#include "yaffs_guts.h"
+
+void yaffs_verify_blk(struct yaffs_dev *dev, struct yaffs_block_info *bi,
+		      int n);
+void yaffs_verify_collected_blk(struct yaffs_dev *dev,
+				struct yaffs_block_info *bi, int n);
+void yaffs_verify_blocks(struct yaffs_dev *dev);
+
+void yaffs_verify_oh(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh,
+		     struct yaffs_ext_tags *tags, int parent_check);
+void yaffs_verify_file(struct yaffs_obj *obj);
+void yaffs_verify_link(struct yaffs_obj *obj);
+void yaffs_verify_symlink(struct yaffs_obj *obj);
+void yaffs_verify_special(struct yaffs_obj *obj);
+void yaffs_verify_obj(struct yaffs_obj *obj);
+void yaffs_verify_objects(struct yaffs_dev *dev);
+void yaffs_verify_obj_in_dir(struct yaffs_obj *obj);
+void yaffs_verify_dir(struct yaffs_obj *directory);
+void yaffs_verify_free_chunks(struct yaffs_dev *dev);
+
+int yaffs_verify_file_sane(struct yaffs_obj *obj);
+
+int yaffs_skip_verification(struct yaffs_dev *dev);
+
+#endif
-- 
1.7.1

Re: [PATCH 06/10] Add yaffs2 file system: Tracing and verification code

[Ryan Mallon]

On 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Some comments below.

~Ryan

> ---
>  fs/yaffs2/yaffs_tagsvalidity.c |   26 ++
>  fs/yaffs2/yaffs_tagsvalidity.h |   23 ++
>  fs/yaffs2/yaffs_trace.h        |   57 +++++
>  fs/yaffs2/yaffs_verify.c       |  524 ++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_verify.h       |   43 ++++
>  5 files changed, 673 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_tagsvalidity.c
>  create mode 100644 fs/yaffs2/yaffs_tagsvalidity.h
>  create mode 100644 fs/yaffs2/yaffs_trace.h
>  create mode 100644 fs/yaffs2/yaffs_verify.c
>  create mode 100644 fs/yaffs2/yaffs_verify.h
> 
> diff --git a/fs/yaffs2/yaffs_tagsvalidity.c b/fs/yaffs2/yaffs_tagsvalidity.c
> new file mode 100644
> index 0000000..582f36a
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_tagsvalidity.c
> @@ -0,0 +1,26 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_tagsvalidity.h"
> +
> +void yaffs_init_tags(struct yaffs_ext_tags *tags)
> +{
> +	memset(tags, 0, sizeof(struct yaffs_ext_tags));
> +	tags->validity0 = 0xAAAAAAAA;
> +	tags->validity1 = 0x55555555;
> +}
> +
> +int yaffs_validate_tags(struct yaffs_ext_tags *tags)
> +{
> +	return (tags->validity0 == 0xAAAAAAAA && tags->validity1 == 0x55555555);
> +}

These are simple enough that they could be made static inline in the
yaffs_tagsvalidity.h header file and drop the c file altogether. You
could further reduce the file count by merging it all with
yaffs_tagscompat.[ch]

> diff --git a/fs/yaffs2/yaffs_tagsvalidity.h b/fs/yaffs2/yaffs_tagsvalidity.h
> new file mode 100644
> index 0000000..36a021f
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_tagsvalidity.h
> @@ -0,0 +1,23 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_TAGS_VALIDITY_H__
> +#define __YAFFS_TAGS_VALIDITY_H__
> +
> +#include "yaffs_guts.h"
> +
> +void yaffs_init_tags(struct yaffs_ext_tags *tags);
> +int yaffs_validate_tags(struct yaffs_ext_tags *tags);
> +#endif
> diff --git a/fs/yaffs2/yaffs_trace.h b/fs/yaffs2/yaffs_trace.h
> new file mode 100644
> index 0000000..6273dbf
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_trace.h
> @@ -0,0 +1,57 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YTRACE_H__
> +#define __YTRACE_H__
> +
> +extern unsigned int yaffs_trace_mask;
> +extern unsigned int yaffs_wr_attempts;
> +
> +/*
> + * Tracing flags.
> + * The flags masked in YAFFS_TRACE_ALWAYS are always traced.
> + */
> +
> +#define YAFFS_TRACE_OS			0x00000002
> +#define YAFFS_TRACE_ALLOCATE		0x00000004
> +#define YAFFS_TRACE_SCAN		0x00000008
> +#define YAFFS_TRACE_BAD_BLOCKS		0x00000010
> +#define YAFFS_TRACE_ERASE		0x00000020
> +#define YAFFS_TRACE_GC			0x00000040
> +#define YAFFS_TRACE_WRITE		0x00000080
> +#define YAFFS_TRACE_TRACING		0x00000100
> +#define YAFFS_TRACE_DELETION		0x00000200
> +#define YAFFS_TRACE_BUFFERS		0x00000400
> +#define YAFFS_TRACE_NANDACCESS		0x00000800
> +#define YAFFS_TRACE_GC_DETAIL		0x00001000
> +#define YAFFS_TRACE_SCAN_DEBUG		0x00002000
> +#define YAFFS_TRACE_MTD			0x00004000
> +#define YAFFS_TRACE_CHECKPOINT		0x00008000
> +
> +#define YAFFS_TRACE_VERIFY		0x00010000
> +#define YAFFS_TRACE_VERIFY_NAND		0x00020000
> +#define YAFFS_TRACE_VERIFY_FULL		0x00040000
> +#define YAFFS_TRACE_VERIFY_ALL		0x000F0000
> +
> +#define YAFFS_TRACE_SYNC		0x00100000
> +#define YAFFS_TRACE_BACKGROUND		0x00200000
> +#define YAFFS_TRACE_LOCK		0x00400000
> +#define YAFFS_TRACE_MOUNT		0x00800000
> +
> +#define YAFFS_TRACE_ERROR		0x40000000
> +#define YAFFS_TRACE_BUG			0x80000000
> +#define YAFFS_TRACE_ALWAYS		0xF0000000
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_verify.c b/fs/yaffs2/yaffs_verify.c
> new file mode 100644
> index 0000000..1a5ed9a
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_verify.c
> @@ -0,0 +1,524 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_verify.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_bitmap.h"
> +#include "yaffs_getblockinfo.h"
> +#include "yaffs_nand.h"
> +
> +int yaffs_skip_verification(struct yaffs_dev *dev)
> +{
> +	dev = dev;

Mark dev as __always_unused if this causes a build warning. Same in
other functions.

> +	return !(yaffs_trace_mask &
> +		 (YAFFS_TRACE_VERIFY | YAFFS_TRACE_VERIFY_FULL));
> +}
> +
> +static int yaffs_skip_full_verification(struct yaffs_dev *dev)
> +{
> +	dev = dev;
> +	return !(yaffs_trace_mask & (YAFFS_TRACE_VERIFY_FULL));
> +}
> +
> +static int yaffs_skip_nand_verification(struct yaffs_dev *dev)
> +{
> +	dev = dev;
> +	return !(yaffs_trace_mask & (YAFFS_TRACE_VERIFY_NAND));
> +}
> +
> +static const char * const block_state_name[] = {
> +	"Unknown",
> +	"Needs scanning",
> +	"Scanning",
> +	"Empty",
> +	"Allocating",
> +	"Full",
> +	"Dirty",
> +	"Checkpoint",
> +	"Collecting",
> +	"Dead"
> +};
> +
> +void yaffs_verify_blk(struct yaffs_dev *dev, struct yaffs_block_info *bi, int n)
> +{
> +	int actually_used;
> +	int in_use;
> +
> +	if (yaffs_skip_verification(dev))
> +		return;
> +
> +	/* Report illegal runtime states */
> +	if (bi->block_state >= YAFFS_NUMBER_OF_BLOCK_STATES)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Block %d has undefined state %d",
> +			n, bi->block_state);
> +
> +	switch (bi->block_state) {
> +	case YAFFS_BLOCK_STATE_UNKNOWN:
> +	case YAFFS_BLOCK_STATE_SCANNING:
> +	case YAFFS_BLOCK_STATE_NEEDS_SCANNING:
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Block %d has bad run-state %s",
> +			n, block_state_name[bi->block_state]);
> +	}
> +
> +	/* Check pages in use and soft deletions are legal */
> +
> +	actually_used = bi->pages_in_use - bi->soft_del_pages;
> +
> +	if (bi->pages_in_use < 0
> +	    || bi->pages_in_use > dev->param.chunks_per_block
> +	    || bi->soft_del_pages < 0
> +	    || bi->soft_del_pages > dev->param.chunks_per_block
> +	    || actually_used < 0 || actually_used > dev->param.chunks_per_block)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Block %d has illegal values pages_in_used %d soft_del_pages %d",
> +			n, bi->pages_in_use, bi->soft_del_pages);
> +
> +	/* Check chunk bitmap legal */
> +	in_use = yaffs_count_chunk_bits(dev, n);
> +	if (in_use != bi->pages_in_use)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Block %d has inconsistent values pages_in_use %d counted chunk bits %d",
> +			n, bi->pages_in_use, in_use);
> +}
> +
> +void yaffs_verify_collected_blk(struct yaffs_dev *dev,
> +				struct yaffs_block_info *bi, int n)
> +{
> +	yaffs_verify_blk(dev, bi, n);
> +
> +	/* After collection the block should be in the erased state */
> +
> +	if (bi->block_state != YAFFS_BLOCK_STATE_COLLECTING &&
> +	    bi->block_state != YAFFS_BLOCK_STATE_EMPTY) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"Block %d is in state %d after gc, should be erased",
> +			n, bi->block_state);
> +	}
> +}
> +
> +void yaffs_verify_blocks(struct yaffs_dev *dev)
> +{
> +	int i;
> +	int state_count[YAFFS_NUMBER_OF_BLOCK_STATES];
> +	int illegal_states = 0;
> +
> +	if (yaffs_skip_verification(dev))
> +		return;
> +
> +	memset(state_count, 0, sizeof(state_count));
> +
> +	for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
> +		struct yaffs_block_info *bi = yaffs_get_block_info(dev, i);
> +		yaffs_verify_blk(dev, bi, i);
> +
> +		if (bi->block_state < YAFFS_NUMBER_OF_BLOCK_STATES)
> +			state_count[bi->block_state]++;
> +		else
> +			illegal_states++;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_VERIFY,	"Block summary");
> +
> +	yaffs_trace(YAFFS_TRACE_VERIFY,
> +		"%d blocks have illegal states",
> +		illegal_states);
> +	if (state_count[YAFFS_BLOCK_STATE_ALLOCATING] > 1)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Too many allocating blocks");
> +
> +	for (i = 0; i < YAFFS_NUMBER_OF_BLOCK_STATES; i++)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"%s %d blocks",
> +			block_state_name[i], state_count[i]);
> +
> +	if (dev->blocks_in_checkpt != state_count[YAFFS_BLOCK_STATE_CHECKPOINT])
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Checkpoint block count wrong dev %d count %d",
> +			dev->blocks_in_checkpt,
> +			state_count[YAFFS_BLOCK_STATE_CHECKPOINT]);
> +
> +	if (dev->n_erased_blocks != state_count[YAFFS_BLOCK_STATE_EMPTY])
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Erased block count wrong dev %d count %d",
> +			dev->n_erased_blocks,
> +			state_count[YAFFS_BLOCK_STATE_EMPTY]);
> +
> +	if (state_count[YAFFS_BLOCK_STATE_COLLECTING] > 1)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Too many collecting blocks %d (max is 1)",
> +			state_count[YAFFS_BLOCK_STATE_COLLECTING]);
> +}
> +
> +/*
> + * Verify the object header. oh must be valid, but obj and tags may be NULL in
> + * which case those tests will not be performed.
> + */
> +void yaffs_verify_oh(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh,
> +		     struct yaffs_ext_tags *tags, int parent_check)
> +{
> +	if (obj && yaffs_skip_verification(obj->my_dev))
> +		return;
> +
> +	if (!(tags && obj && oh)) {
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Verifying object header tags %p obj %p oh %p",
> +			tags, obj, oh);
> +		return;
> +	}
> +
> +	if (oh->type <= YAFFS_OBJECT_TYPE_UNKNOWN ||
> +	    oh->type > YAFFS_OBJECT_TYPE_MAX)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d header type is illegal value 0x%x",
> +			tags->obj_id, oh->type);
> +
> +	if (tags->obj_id != obj->obj_id)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d header mismatch obj_id %d",
> +			tags->obj_id, obj->obj_id);
> +
> +	/*
> +	 * Check that the object's parent ids match if parent_check requested.
> +	 *
> +	 * Tests do not apply to the root object.
> +	 */
> +
> +	if (parent_check && tags->obj_id > 1 && !obj->parent)
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d header mismatch parent_id %d obj->parent is NULL",
> +			tags->obj_id, oh->parent_obj_id);
> +
> +	if (parent_check && obj->parent &&
> +	    oh->parent_obj_id != obj->parent->obj_id &&
> +	    (oh->parent_obj_id != YAFFS_OBJECTID_UNLINKED ||
> +	     obj->parent->obj_id != YAFFS_OBJECTID_DELETED))
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d header mismatch parent_id %d parent_obj_id %d",
> +			tags->obj_id, oh->parent_obj_id,
> +			obj->parent->obj_id);
> +
> +	if (tags->obj_id > 1 && oh->name[0] == 0)	/* Null name */
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d header name is NULL",
> +			obj->obj_id);
> +
> +	if (tags->obj_id > 1 && ((u8) (oh->name[0])) == 0xff)	/* Junk name */
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d header name is 0xFF",
> +			obj->obj_id);
> +}
> +
> +void yaffs_verify_file(struct yaffs_obj *obj)
> +{
> +	int required_depth;
> +	int actual_depth;
> +	u32 last_chunk;
> +	u32 x;
> +	u32 i;
> +	struct yaffs_dev *dev;
> +	struct yaffs_ext_tags tags;
> +	struct yaffs_tnode *tn;
> +	u32 obj_id;
> +
> +	if (!obj)
> +		return;
> +
> +	if (yaffs_skip_verification(obj->my_dev))
> +		return;
> +
> +	dev = obj->my_dev;
> +	obj_id = obj->obj_id;
> +
> +	/* Check file size is consistent with tnode depth */
> +	last_chunk =
> +	    obj->variant.file_variant.file_size / dev->data_bytes_per_chunk + 1;
> +	x = last_chunk >> YAFFS_TNODES_LEVEL0_BITS;
> +	required_depth = 0;
> +	while (x > 0) {
> +		x >>= YAFFS_TNODES_INTERNAL_BITS;
> +		required_depth++;
> +	}
> +
> +	actual_depth = obj->variant.file_variant.top_level;
> +
> +	/* Check that the chunks in the tnode tree are all correct.
> +	 * We do this by scanning through the tnode tree and
> +	 * checking the tags for every chunk match.
> +	 */
> +
> +	if (yaffs_skip_nand_verification(dev))
> +		return;
> +
> +	for (i = 1; i <= last_chunk; i++) {
> +		tn = yaffs_find_tnode_0(dev, &obj->variant.file_variant, i);
> +
> +		if (tn) {
> +			u32 the_chunk = yaffs_get_group_base(dev, tn, i);
> +			if (the_chunk > 0) {


You can reduce the indentation level by doing:
		
		if (!tn)
			continue;

		the_chunk = yaffs_get_group_base(dev, tn, i);
		if (!the_chunk)
			continue;

> +				yaffs_rd_chunk_tags_nand(dev, the_chunk, NULL,
> +							 &tags);
> +				if (tags.obj_id != obj_id || tags.chunk_id != i)
> +					yaffs_trace(YAFFS_TRACE_VERIFY,
> +						"Object %d chunk_id %d NAND mismatch chunk %d tags (%d:%d)",
> +						obj_id, i, the_chunk,
> +						tags.obj_id, tags.chunk_id);
> +			}
> +		}
> +	}
> +}
> +
> +void yaffs_verify_link(struct yaffs_obj *obj)
> +{
> +	if (obj && yaffs_skip_verification(obj->my_dev))
> +		return;
> +

This (and the functions below) doesn't do anything. What's it for?

> +	/* Verify sane equivalent object */
> +}
> +
> +void yaffs_verify_symlink(struct yaffs_obj *obj)
> +{
> +	if (obj && yaffs_skip_verification(obj->my_dev))
> +		return;
> +
> +	/* Verify symlink string */
> +}
> +
> +void yaffs_verify_special(struct yaffs_obj *obj)
> +{
> +	if (obj && yaffs_skip_verification(obj->my_dev))
> +		return;
> +}
> +
> +void yaffs_verify_obj(struct yaffs_obj *obj)
> +{
> +	struct yaffs_dev *dev;
> +	u32 chunk_min;
> +	u32 chunk_max;
> +	u32 chunk_id_ok;
> +	u32 chunk_in_range;
> +	u32 chunk_wrongly_deleted;
> +	u32 chunk_valid;
> +
> +	if (!obj)
> +		return;
> +
> +	if (obj->being_created)
> +		return;
> +
> +	dev = obj->my_dev;
> +
> +	if (yaffs_skip_verification(dev))
> +		return;
> +
> +	/* Check sane object header chunk */
> +
> +	chunk_min = dev->internal_start_block * dev->param.chunks_per_block;
> +	chunk_max =
> +	    (dev->internal_end_block + 1) * dev->param.chunks_per_block - 1;
> +
> +	chunk_in_range = (((unsigned)(obj->hdr_chunk)) >= chunk_min &&
> +			  ((unsigned)(obj->hdr_chunk)) <= chunk_max);
> +	chunk_id_ok = chunk_in_range || (obj->hdr_chunk == 0);
> +	chunk_valid = chunk_in_range &&
> +	    yaffs_check_chunk_bit(dev,
> +				  obj->hdr_chunk / dev->param.chunks_per_block,
> +				  obj->hdr_chunk % dev->param.chunks_per_block);
> +	chunk_wrongly_deleted = chunk_in_range && !chunk_valid;
> +
> +	if (!obj->fake && (!chunk_id_ok || chunk_wrongly_deleted))
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d has chunk_id %d %s %s",
> +			obj->obj_id, obj->hdr_chunk,
> +			chunk_id_ok ? "" : ",out of range",
> +			chunk_wrongly_deleted ? ",marked as deleted" : "");
> +
> +	if (chunk_valid && !yaffs_skip_nand_verification(dev)) {
> +		struct yaffs_ext_tags tags;
> +		struct yaffs_obj_hdr *oh;
> +		u8 *buffer = yaffs_get_temp_buffer(dev, __LINE__);
> +
> +		oh = (struct yaffs_obj_hdr *)buffer;
> +
> +		yaffs_rd_chunk_tags_nand(dev, obj->hdr_chunk, buffer, &tags);
> +
> +		yaffs_verify_oh(obj, oh, &tags, 1);
> +
> +		yaffs_release_temp_buffer(dev, buffer, __LINE__);
> +	}
> +
> +	/* Verify it has a parent */
> +	if (obj && !obj->fake && (!obj->parent || obj->parent->my_dev != dev)) {
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d has parent pointer %p which does not look like an object",
> +			obj->obj_id, obj->parent);
> +	}
> +
> +	/* Verify parent is a directory */
> +	if (obj->parent
> +	    && obj->parent->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d's parent is not a directory (type %d)",
> +			obj->obj_id, obj->parent->variant_type);
> +	}
> +
> +	switch (obj->variant_type) {
> +	case YAFFS_OBJECT_TYPE_FILE:
> +		yaffs_verify_file(obj);
> +		break;
> +	case YAFFS_OBJECT_TYPE_SYMLINK:
> +		yaffs_verify_symlink(obj);
> +		break;
> +	case YAFFS_OBJECT_TYPE_DIRECTORY:
> +		yaffs_verify_dir(obj);
> +		break;
> +	case YAFFS_OBJECT_TYPE_HARDLINK:
> +		yaffs_verify_link(obj);
> +		break;
> +	case YAFFS_OBJECT_TYPE_SPECIAL:
> +		yaffs_verify_special(obj);
> +		break;

Print a warning/do nothing for the verifications which have empty functions?

> +	case YAFFS_OBJECT_TYPE_UNKNOWN:
> +	default:
> +		yaffs_trace(YAFFS_TRACE_VERIFY,
> +			"Obj %d has illegaltype %d",
> +		   obj->obj_id, obj->variant_type);
> +		break;
> +	}
> +}
> +
> +void yaffs_verify_objects(struct yaffs_dev *dev)
> +{
> +	struct yaffs_obj *obj;
> +	int i;
> +	struct list_head *lh;
> +
> +	if (yaffs_skip_verification(dev))
> +		return;
> +
> +	/* Iterate through the objects in each hash entry */
> +
> +	for (i = 0; i < YAFFS_NOBJECT_BUCKETS; i++) {
> +		list_for_each(lh, &dev->obj_bucket[i].list) {
> +			obj = list_entry(lh, struct yaffs_obj, hash_link);

	list_for_each_entry(lh, &dev->obj_bucket[i].list, hash_link)

> +			yaffs_verify_obj(obj);
> +		}
> +	}
> +}
> +
> +void yaffs_verify_obj_in_dir(struct yaffs_obj *obj)
> +{
> +	struct list_head *lh;
> +	struct yaffs_obj *list_obj;
> +	int count = 0;
> +
> +	if (!obj) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS, "No object to verify");
> +		YBUG();
> +		return;
> +	}
> +
> +	if (yaffs_skip_verification(obj->my_dev))
> +		return;
> +
> +	if (!obj->parent) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS, "Object does not have parent");
> +		YBUG();
> +		return;
> +	}
> +
> +	if (obj->parent->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS, "Parent is not directory");
> +		YBUG();
> +	}
> +
> +	/* Iterate through the objects in each hash entry */
> +
> +	list_for_each(lh, &obj->parent->variant.dir_variant.children) {
> +		list_obj = list_entry(lh, struct yaffs_obj, siblings);

	list_for_each_entry(lh,
		&obj->parent->variant.dir_variant.children, siblings) {

> +		yaffs_verify_obj(list_obj);
> +		if (obj == list_obj)
> +			count++;
> +	}
> +
> +	if (count != 1) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"Object in directory %d times",
> +			count);
> +		YBUG();
> +	}
> +}
> +
> +void yaffs_verify_dir(struct yaffs_obj *directory)
> +{
> +	struct list_head *lh;
> +	struct yaffs_obj *list_obj;
> +
> +	if (!directory) {
> +		YBUG();
> +		return;
> +	}
> +
> +	if (yaffs_skip_full_verification(directory->my_dev))
> +		return;
> +
> +	if (directory->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"Directory has wrong type: %d",
> +			directory->variant_type);
> +		YBUG();
> +	}
> +
> +	/* Iterate through the objects in each hash entry */
> +
> +	list_for_each(lh, &directory->variant.dir_variant.children) {
> +		list_obj = list_entry(lh, struct yaffs_obj, siblings);

	list_for_each_entry(lh,
		&directory->variant.dir_variant.children, siblings)

> +		if (list_obj->parent != directory) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"Object in directory list has wrong parent %p",
> +				list_obj->parent);
> +			YBUG();
> +		}
> +		yaffs_verify_obj_in_dir(list_obj);
> +	}
> +}
> +
> +static int yaffs_free_verification_failures;
> +
> +void yaffs_verify_free_chunks(struct yaffs_dev *dev)
> +{
> +	int counted;
> +	int difference;
> +
> +	if (yaffs_skip_verification(dev))
> +		return;
> +
> +	counted = yaffs_count_free_chunks(dev);
> +
> +	difference = dev->n_free_chunks - counted;
> +
> +	if (difference) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"Freechunks verification failure %d %d %d",
> +			dev->n_free_chunks, counted, difference);
> +		yaffs_free_verification_failures++;
> +	}
> +}
> +
> +int yaffs_verify_file_sane(struct yaffs_obj *in)
> +{
> +	in = in;
> +	return YAFFS_OK;
> +}

Useless function.

> +
> diff --git a/fs/yaffs2/yaffs_verify.h b/fs/yaffs2/yaffs_verify.h
> new file mode 100644
> index 0000000..cc6f889
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_verify.h
> @@ -0,0 +1,43 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_VERIFY_H__
> +#define __YAFFS_VERIFY_H__
> +
> +#include "yaffs_guts.h"
> +
> +void yaffs_verify_blk(struct yaffs_dev *dev, struct yaffs_block_info *bi,
> +		      int n);
> +void yaffs_verify_collected_blk(struct yaffs_dev *dev,
> +				struct yaffs_block_info *bi, int n);
> +void yaffs_verify_blocks(struct yaffs_dev *dev);
> +
> +void yaffs_verify_oh(struct yaffs_obj *obj, struct yaffs_obj_hdr *oh,
> +		     struct yaffs_ext_tags *tags, int parent_check);
> +void yaffs_verify_file(struct yaffs_obj *obj);
> +void yaffs_verify_link(struct yaffs_obj *obj);
> +void yaffs_verify_symlink(struct yaffs_obj *obj);
> +void yaffs_verify_special(struct yaffs_obj *obj);
> +void yaffs_verify_obj(struct yaffs_obj *obj);
> +void yaffs_verify_objects(struct yaffs_dev *dev);
> +void yaffs_verify_obj_in_dir(struct yaffs_obj *obj);
> +void yaffs_verify_dir(struct yaffs_obj *directory);
> +void yaffs_verify_free_chunks(struct yaffs_dev *dev);
> +
> +int yaffs_verify_file_sane(struct yaffs_obj *obj);
> +
> +int yaffs_skip_verification(struct yaffs_dev *dev);
> +
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 07/10] Add yaffs2 file system: yaffs1 and yaffs2 mode specific code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_yaffs1.c |  423 +++++++++++++
 fs/yaffs2/yaffs_yaffs1.h |   22 +
 fs/yaffs2/yaffs_yaffs2.c | 1516 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_yaffs2.h |   39 ++
 4 files changed, 2000 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_yaffs1.c
 create mode 100644 fs/yaffs2/yaffs_yaffs1.h
 create mode 100644 fs/yaffs2/yaffs_yaffs2.c
 create mode 100644 fs/yaffs2/yaffs_yaffs2.h

diff --git a/fs/yaffs2/yaffs_yaffs1.c b/fs/yaffs2/yaffs_yaffs1.c
new file mode 100644
index 0000000..6ee91a1
--- /dev/null
+++ b/fs/yaffs2/yaffs_yaffs1.c
@@ -0,0 +1,423 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_yaffs1.h"
+#include "yportenv.h"
+#include "yaffs_trace.h"
+#include "yaffs_bitmap.h"
+#include "yaffs_getblockinfo.h"
+#include "yaffs_nand.h"
+#include "yaffs_attribs.h"
+
+int yaffs1_scan(struct yaffs_dev *dev)
+{
+	struct yaffs_ext_tags tags;
+	int blk;
+	int result;
+	int chunk;
+	int c;
+	int deleted;
+	enum yaffs_block_state state;
+	struct yaffs_obj *hard_list = NULL;
+	struct yaffs_block_info *bi;
+	u32 seq_number;
+	struct yaffs_obj_hdr *oh;
+	struct yaffs_obj *in;
+	struct yaffs_obj *parent;
+	int alloc_failed = 0;
+	struct yaffs_shadow_fixer *shadow_fixers = NULL;
+	u8 *chunk_data;
+
+	yaffs_trace(YAFFS_TRACE_SCAN,
+		"yaffs1_scan starts  intstartblk %d intendblk %d...",
+		dev->internal_start_block, dev->internal_end_block);
+
+	chunk_data = yaffs_get_temp_buffer(dev, __LINE__);
+
+	dev->seq_number = YAFFS_LOWEST_SEQUENCE_NUMBER;
+
+	/* Scan all the blocks to determine their state */
+	bi = dev->block_info;
+	for (blk = dev->internal_start_block; blk <= dev->internal_end_block;
+	     blk++) {
+		yaffs_clear_chunk_bits(dev, blk);
+		bi->pages_in_use = 0;
+		bi->soft_del_pages = 0;
+
+		yaffs_query_init_block_state(dev, blk, &state, &seq_number);
+
+		bi->block_state = state;
+		bi->seq_number = seq_number;
+
+		if (bi->seq_number == YAFFS_SEQUENCE_BAD_BLOCK)
+			bi->block_state = state = YAFFS_BLOCK_STATE_DEAD;
+
+		yaffs_trace(YAFFS_TRACE_SCAN_DEBUG,
+			"Block scanning block %d state %d seq %d",
+			blk, state, seq_number);
+
+		if (state == YAFFS_BLOCK_STATE_DEAD) {
+			yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
+				"block %d is bad", blk);
+		} else if (state == YAFFS_BLOCK_STATE_EMPTY) {
+			yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "Block empty ");
+			dev->n_erased_blocks++;
+			dev->n_free_chunks += dev->param.chunks_per_block;
+		}
+		bi++;
+	}
+
+	/* For each block.... */
+	for (blk = dev->internal_start_block;
+	     !alloc_failed && blk <= dev->internal_end_block; blk++) {
+
+		cond_resched();
+
+		bi = yaffs_get_block_info(dev, blk);
+		state = bi->block_state;
+
+		deleted = 0;
+
+		/* For each chunk in each block that needs scanning.... */
+		for (c = 0; !alloc_failed && c < dev->param.chunks_per_block &&
+		     state == YAFFS_BLOCK_STATE_NEEDS_SCANNING; c++) {
+			/* Read the tags and decide what to do */
+			chunk = blk * dev->param.chunks_per_block + c;
+
+			result = yaffs_rd_chunk_tags_nand(dev, chunk, NULL,
+							  &tags);
+
+			/* Let's have a good look at this chunk... */
+
+			if (tags.ecc_result == YAFFS_ECC_RESULT_UNFIXED
+			    || tags.is_deleted) {
+				/* YAFFS1 only...
+				 * A deleted chunk
+				 */
+				deleted++;
+				dev->n_free_chunks++;
+			} else if (!tags.chunk_used) {
+				/* An unassigned chunk in the block
+				 * This means that either the block is empty or
+				 * this is the one being allocated from
+				 */
+
+				if (c == 0) {
+					/* We're looking at the first chunk in
+					 *the block so the block is unused */
+					state = YAFFS_BLOCK_STATE_EMPTY;
+					dev->n_erased_blocks++;
+				} else {
+					/* this is the block being allocated */
+					yaffs_trace(YAFFS_TRACE_SCAN,
+						" Allocating from %d %d",
+						blk, c);
+					state = YAFFS_BLOCK_STATE_ALLOCATING;
+					dev->alloc_block = blk;
+					dev->alloc_page = c;
+					dev->alloc_block_finder = blk;
+
+				}
+
+				dev->n_free_chunks +=
+				    (dev->param.chunks_per_block - c);
+			} else if (tags.chunk_id > 0) {
+				/* chunk_id > 0 so it is a data chunk... */
+				unsigned int endpos;
+
+				yaffs_set_chunk_bit(dev, blk, c);
+				bi->pages_in_use++;
+
+				in = yaffs_find_or_create_by_number(dev,
+							tags.obj_id,
+							YAFFS_OBJECT_TYPE_FILE);
+				/* PutChunkIntoFile checks for a clash
+				 * (two data chunks with the same chunk_id).
+				 */
+
+				if (!in)
+					alloc_failed = 1;
+
+				if (in) {
+					if (!yaffs_put_chunk_in_file
+					    (in, tags.chunk_id, chunk, 1))
+						alloc_failed = 1;
+				}
+
+				endpos =
+				    (tags.chunk_id - 1) *
+				    dev->data_bytes_per_chunk +
+				    tags.n_bytes;
+				if (in &&
+				    in->variant_type ==
+				    YAFFS_OBJECT_TYPE_FILE &&
+				    in->variant.file_variant.scanned_size <
+				    endpos) {
+					in->variant.file_variant.scanned_size =
+					    endpos;
+					if (!dev->param.use_header_file_size) {
+						in->variant.
+						    file_variant.file_size =
+						    in->variant.
+						    file_variant.scanned_size;
+					}
+
+				}
+			} else {
+				/* chunk_id == 0, so it is an ObjectHeader.
+				 * Make the object
+				 */
+				yaffs_set_chunk_bit(dev, blk, c);
+				bi->pages_in_use++;
+
+				result = yaffs_rd_chunk_tags_nand(dev, chunk,
+								  chunk_data,
+								  NULL);
+
+				oh = (struct yaffs_obj_hdr *)chunk_data;
+
+				in = yaffs_find_by_number(dev, tags.obj_id);
+				if (in && in->variant_type != oh->type) {
+					/* This should not happen, but somehow
+					 * Wev'e ended up with an obj_id that
+					 * has been reused but not yet deleted,
+					 * and worse still it has changed type.
+					 * Delete the old object.
+					 */
+
+					yaffs_del_obj(in);
+					in = NULL;
+				}
+
+				in = yaffs_find_or_create_by_number(dev,
+								tags.obj_id,
+								oh->type);
+
+				if (!in)
+					alloc_failed = 1;
+
+				if (in && oh->shadows_obj > 0) {
+
+					struct yaffs_shadow_fixer *fixer;
+					fixer =
+						kmalloc(sizeof
+						(struct yaffs_shadow_fixer),
+						GFP_NOFS);
+					if (fixer) {
+						fixer->next = shadow_fixers;
+						shadow_fixers = fixer;
+						fixer->obj_id = tags.obj_id;
+						fixer->shadowed_id =
+						    oh->shadows_obj;
+						yaffs_trace(YAFFS_TRACE_SCAN,
+							" Shadow fixer: %d shadows %d",
+							fixer->obj_id,
+							fixer->shadowed_id);
+
+					}
+
+				}
+
+				if (in && in->valid) {
+					/* We have already filled this one.
+					 * We have a duplicate and need to
+					 * resolve it. */
+
+					unsigned existing_serial = in->serial;
+					unsigned new_serial =
+					    tags.serial_number;
+
+					if (((existing_serial + 1) & 3) ==
+					    new_serial) {
+						/* Use new one - destroy the
+						 * exisiting one */
+						yaffs_chunk_del(dev,
+								in->hdr_chunk,
+								1, __LINE__);
+						in->valid = 0;
+					} else {
+						/* Use existing - destroy
+						 * this one. */
+						yaffs_chunk_del(dev, chunk, 1,
+								__LINE__);
+					}
+				}
+
+				if (in && !in->valid &&
+				    (tags.obj_id == YAFFS_OBJECTID_ROOT ||
+				     tags.obj_id ==
+				     YAFFS_OBJECTID_LOSTNFOUND)) {
+					/* We only load some info, don't fiddle
+					 * with directory structure */
+					in->valid = 1;
+					in->variant_type = oh->type;
+
+					in->yst_mode = oh->yst_mode;
+					yaffs_load_attribs(in, oh);
+					in->hdr_chunk = chunk;
+					in->serial = tags.serial_number;
+
+				} else if (in && !in->valid) {
+					/* we need to load this info */
+
+					in->valid = 1;
+					in->variant_type = oh->type;
+
+					in->yst_mode = oh->yst_mode;
+					yaffs_load_attribs(in, oh);
+					in->hdr_chunk = chunk;
+					in->serial = tags.serial_number;
+
+					yaffs_set_obj_name_from_oh(in, oh);
+					in->dirty = 0;
+
+					/* directory stuff...
+					 * hook up to parent
+					 */
+
+					parent =
+					    yaffs_find_or_create_by_number
+					    (dev, oh->parent_obj_id,
+					     YAFFS_OBJECT_TYPE_DIRECTORY);
+					if (!parent)
+						alloc_failed = 1;
+					if (parent && parent->variant_type ==
+					    YAFFS_OBJECT_TYPE_UNKNOWN) {
+						/* Set up as a directory */
+						parent->variant_type =
+						    YAFFS_OBJECT_TYPE_DIRECTORY;
+						INIT_LIST_HEAD(&parent->
+							variant.dir_variant.
+							children);
+					} else if (!parent ||
+						parent->variant_type !=
+						YAFFS_OBJECT_TYPE_DIRECTORY) {
+						/* Hoosterman, a problem....
+						 * We're trying to use a
+						 * non-directory as a directory
+						 */
+
+						yaffs_trace(YAFFS_TRACE_ERROR,
+							"yaffs tragedy: attempting to use non-directory as a directory in scan. Put in lost+found."
+							);
+						parent = dev->lost_n_found;
+					}
+
+					yaffs_add_obj_to_dir(parent, in);
+
+					switch (in->variant_type) {
+					case YAFFS_OBJECT_TYPE_UNKNOWN:
+						/* Todo got a problem */
+						break;
+					case YAFFS_OBJECT_TYPE_FILE:
+						if (dev->param.
+						    use_header_file_size)
+
+							in->variant.
+							 file_variant.file_size
+							    = oh->file_size;
+
+						break;
+					case YAFFS_OBJECT_TYPE_HARDLINK:
+						in->variant.
+						    hardlink_variant.equiv_id =
+						    oh->equiv_id;
+						in->hard_links.next =
+						    (struct list_head *)
+						    hard_list;
+						hard_list = in;
+						break;
+					case YAFFS_OBJECT_TYPE_DIRECTORY:
+						/* Do nothing */
+						break;
+					case YAFFS_OBJECT_TYPE_SPECIAL:
+						/* Do nothing */
+						break;
+					case YAFFS_OBJECT_TYPE_SYMLINK:
+						in->variant.symlink_variant.
+						    alias =
+						    yaffs_clone_str(oh->alias);
+						if (!in->variant.
+						    symlink_variant.alias)
+							alloc_failed = 1;
+						break;
+					}
+				}
+			}
+		}
+
+		if (state == YAFFS_BLOCK_STATE_NEEDS_SCANNING) {
+			/* If we got this far while scanning,
+			 * then the block is fully allocated. */
+			state = YAFFS_BLOCK_STATE_FULL;
+		}
+
+		if (state == YAFFS_BLOCK_STATE_ALLOCATING) {
+			/* If the block was partially allocated then
+			 * treat it as fully allocated. */
+			state = YAFFS_BLOCK_STATE_FULL;
+			dev->alloc_block = -1;
+		}
+
+		bi->block_state = state;
+
+		/* Now let's see if it was dirty */
+		if (bi->pages_in_use == 0 &&
+		    !bi->has_shrink_hdr &&
+		    bi->block_state == YAFFS_BLOCK_STATE_FULL) {
+			yaffs_block_became_dirty(dev, blk);
+		}
+	}
+
+	/* Ok, we've done all the scanning.
+	 * Fix up the hard link chains.
+	 * We should now have scanned all the objects, now it's time to add
+	 * these hardlinks.
+	 */
+
+	yaffs_link_fixup(dev, hard_list);
+
+	/* Fix up any shadowed objects */
+	{
+		struct yaffs_shadow_fixer *fixer;
+		struct yaffs_obj *obj;
+
+		while (shadow_fixers) {
+			fixer = shadow_fixers;
+			shadow_fixers = fixer->next;
+			/* Complete the rename transaction by deleting the
+			 * shadowed object then setting the object header
+			 to unshadowed.
+			 */
+			obj = yaffs_find_by_number(dev, fixer->shadowed_id);
+			if (obj)
+				yaffs_del_obj(obj);
+
+			obj = yaffs_find_by_number(dev, fixer->obj_id);
+
+			if (obj)
+				yaffs_update_oh(obj, NULL, 1, 0, 0, NULL);
+
+			kfree(fixer);
+		}
+	}
+
+	yaffs_release_temp_buffer(dev, chunk_data, __LINE__);
+
+	if (alloc_failed)
+		return YAFFS_FAIL;
+
+	yaffs_trace(YAFFS_TRACE_SCAN, "yaffs1_scan ends");
+
+	return YAFFS_OK;
+}
diff --git a/fs/yaffs2/yaffs_yaffs1.h b/fs/yaffs2/yaffs_yaffs1.h
new file mode 100644
index 0000000..db23e04
--- /dev/null
+++ b/fs/yaffs2/yaffs_yaffs1.h
@@ -0,0 +1,22 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_YAFFS1_H__
+#define __YAFFS_YAFFS1_H__
+
+#include "yaffs_guts.h"
+int yaffs1_scan(struct yaffs_dev *dev);
+
+#endif
diff --git a/fs/yaffs2/yaffs_yaffs2.c b/fs/yaffs2/yaffs_yaffs2.c
new file mode 100644
index 0000000..77101e7
--- /dev/null
+++ b/fs/yaffs2/yaffs_yaffs2.c
@@ -0,0 +1,1516 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yaffs_guts.h"
+#include "yaffs_trace.h"
+#include "yaffs_yaffs2.h"
+#include "yaffs_checkptrw.h"
+#include "yaffs_bitmap.h"
+#include "yaffs_nand.h"
+#include "yaffs_getblockinfo.h"
+#include "yaffs_verify.h"
+#include "yaffs_attribs.h"
+
+/*
+ * Checkpoints are really no benefit on very small partitions.
+ *
+ * To save space on small partitions don't bother with checkpoints unless
+ * the partition is at least this big.
+ */
+#define YAFFS_CHECKPOINT_MIN_BLOCKS 60
+#define YAFFS_SMALL_HOLE_THRESHOLD 4
+
+/*
+ * Oldest Dirty Sequence Number handling.
+ */
+
+/* yaffs_calc_oldest_dirty_seq()
+ * yaffs2_find_oldest_dirty_seq()
+ * Calculate the oldest dirty sequence number if we don't know it.
+ */
+void yaffs_calc_oldest_dirty_seq(struct yaffs_dev *dev)
+{
+	int i;
+	unsigned seq;
+	unsigned block_no = 0;
+	struct yaffs_block_info *b;
+
+	if (!dev->param.is_yaffs2)
+		return;
+
+	/* Find the oldest dirty sequence number. */
+	seq = dev->seq_number + 1;
+	b = dev->block_info;
+	for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
+		if (b->block_state == YAFFS_BLOCK_STATE_FULL &&
+		    (b->pages_in_use - b->soft_del_pages) <
+		    dev->param.chunks_per_block && b->seq_number < seq) {
+			seq = b->seq_number;
+			block_no = i;
+		}
+		b++;
+	}
+
+	if (block_no) {
+		dev->oldest_dirty_seq = seq;
+		dev->oldest_dirty_block = block_no;
+	}
+}
+
+void yaffs2_find_oldest_dirty_seq(struct yaffs_dev *dev)
+{
+	if (!dev->param.is_yaffs2)
+		return;
+
+	if (!dev->oldest_dirty_seq)
+		yaffs_calc_oldest_dirty_seq(dev);
+}
+
+/*
+ * yaffs_clear_oldest_dirty_seq()
+ * Called when a block is erased or marked bad. (ie. when its seq_number
+ * becomes invalid). If the value matches the oldest then we clear
+ * dev->oldest_dirty_seq to force its recomputation.
+ */
+void yaffs2_clear_oldest_dirty_seq(struct yaffs_dev *dev,
+				   struct yaffs_block_info *bi)
+{
+
+	if (!dev->param.is_yaffs2)
+		return;
+
+	if (!bi || bi->seq_number == dev->oldest_dirty_seq) {
+		dev->oldest_dirty_seq = 0;
+		dev->oldest_dirty_block = 0;
+	}
+}
+
+/*
+ * yaffs2_update_oldest_dirty_seq()
+ * Update the oldest dirty sequence number whenever we dirty a block.
+ * Only do this if the oldest_dirty_seq is actually being tracked.
+ */
+void yaffs2_update_oldest_dirty_seq(struct yaffs_dev *dev, unsigned block_no,
+				    struct yaffs_block_info *bi)
+{
+	if (!dev->param.is_yaffs2)
+		return;
+
+	if (dev->oldest_dirty_seq) {
+		if (dev->oldest_dirty_seq > bi->seq_number) {
+			dev->oldest_dirty_seq = bi->seq_number;
+			dev->oldest_dirty_block = block_no;
+		}
+	}
+}
+
+int yaffs_block_ok_for_gc(struct yaffs_dev *dev, struct yaffs_block_info *bi)
+{
+
+	if (!dev->param.is_yaffs2)
+		return 1;	/* disqualification only applies to yaffs2. */
+
+	if (!bi->has_shrink_hdr)
+		return 1;	/* can gc */
+
+	yaffs2_find_oldest_dirty_seq(dev);
+
+	/* Can't do gc of this block if there are any blocks older than this
+	 * one that have discarded pages.
+	 */
+	return (bi->seq_number <= dev->oldest_dirty_seq);
+}
+
+/*
+ * yaffs2_find_refresh_block()
+ * periodically finds the oldest full block by sequence number for refreshing.
+ * Only for yaffs2.
+ */
+u32 yaffs2_find_refresh_block(struct yaffs_dev *dev)
+{
+	u32 b;
+	u32 oldest = 0;
+	u32 oldest_seq = 0;
+	struct yaffs_block_info *bi;
+
+	if (!dev->param.is_yaffs2)
+		return oldest;
+
+	/*
+	 * If refresh period < 10 then refreshing is disabled.
+	 */
+	if (dev->param.refresh_period < 10)
+		return oldest;
+
+	/*
+	 * Fix broken values.
+	 */
+	if (dev->refresh_skip > dev->param.refresh_period)
+		dev->refresh_skip = dev->param.refresh_period;
+
+	if (dev->refresh_skip > 0)
+		return oldest;
+
+	/*
+	 * Refresh skip is now zero.
+	 * We'll do a refresh this time around....
+	 * Update the refresh skip and find the oldest block.
+	 */
+	dev->refresh_skip = dev->param.refresh_period;
+	dev->refresh_count++;
+	bi = dev->block_info;
+	for (b = dev->internal_start_block; b <= dev->internal_end_block; b++) {
+
+		if (bi->block_state == YAFFS_BLOCK_STATE_FULL) {
+
+			if (oldest < 1 || bi->seq_number < oldest_seq) {
+				oldest = b;
+				oldest_seq = bi->seq_number;
+			}
+		}
+		bi++;
+	}
+
+	if (oldest > 0) {
+		yaffs_trace(YAFFS_TRACE_GC,
+			"GC refresh count %d selected block %d with seq_number %d",
+			dev->refresh_count, oldest, oldest_seq);
+	}
+
+	return oldest;
+}
+
+int yaffs2_checkpt_required(struct yaffs_dev *dev)
+{
+	int nblocks;
+
+	if (!dev->param.is_yaffs2)
+		return 0;
+
+	nblocks = dev->internal_end_block - dev->internal_start_block + 1;
+
+	return !dev->param.skip_checkpt_wr &&
+	    !dev->read_only && (nblocks >= YAFFS_CHECKPOINT_MIN_BLOCKS);
+}
+
+int yaffs_calc_checkpt_blocks_required(struct yaffs_dev *dev)
+{
+	int retval;
+
+	if (!dev->param.is_yaffs2)
+		return 0;
+
+	if (!dev->checkpoint_blocks_required && yaffs2_checkpt_required(dev)) {
+		/* Not a valid value so recalculate */
+		int n_bytes = 0;
+		int n_blocks;
+		int dev_blocks =
+		    (dev->param.end_block - dev->param.start_block + 1);
+
+		n_bytes += sizeof(struct yaffs_checkpt_validity);
+		n_bytes += sizeof(struct yaffs_checkpt_dev);
+		n_bytes += dev_blocks * sizeof(struct yaffs_block_info);
+		n_bytes += dev_blocks * dev->chunk_bit_stride;
+		n_bytes +=
+		    (sizeof(struct yaffs_checkpt_obj) + sizeof(u32)) *
+		    dev->n_obj;
+		n_bytes += (dev->tnode_size + sizeof(u32)) * dev->n_tnodes;
+		n_bytes += sizeof(struct yaffs_checkpt_validity);
+		n_bytes += sizeof(u32);	/* checksum */
+
+		/* Round up and add 2 blocks to allow for some bad blocks,
+		 * so add 3 */
+
+		n_blocks =
+		    (n_bytes /
+		     (dev->data_bytes_per_chunk *
+		      dev->param.chunks_per_block)) + 3;
+
+		dev->checkpoint_blocks_required = n_blocks;
+	}
+
+	retval = dev->checkpoint_blocks_required - dev->blocks_in_checkpt;
+	if (retval < 0)
+		retval = 0;
+	return retval;
+}
+
+/*--------------------- Checkpointing --------------------*/
+
+static int yaffs2_wr_checkpt_validity_marker(struct yaffs_dev *dev, int head)
+{
+	struct yaffs_checkpt_validity cp;
+
+	memset(&cp, 0, sizeof(cp));
+
+	cp.struct_type = sizeof(cp);
+	cp.magic = YAFFS_MAGIC;
+	cp.version = YAFFS_CHECKPOINT_VERSION;
+	cp.head = (head) ? 1 : 0;
+
+	return (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp)) ? 1 : 0;
+}
+
+static int yaffs2_rd_checkpt_validity_marker(struct yaffs_dev *dev, int head)
+{
+	struct yaffs_checkpt_validity cp;
+	int ok;
+
+	ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
+
+	if (ok)
+		ok = (cp.struct_type == sizeof(cp)) &&
+		    (cp.magic == YAFFS_MAGIC) &&
+		    (cp.version == YAFFS_CHECKPOINT_VERSION) &&
+		    (cp.head == ((head) ? 1 : 0));
+	return ok ? 1 : 0;
+}
+
+static void yaffs2_dev_to_checkpt_dev(struct yaffs_checkpt_dev *cp,
+				      struct yaffs_dev *dev)
+{
+	cp->n_erased_blocks = dev->n_erased_blocks;
+	cp->alloc_block = dev->alloc_block;
+	cp->alloc_page = dev->alloc_page;
+	cp->n_free_chunks = dev->n_free_chunks;
+
+	cp->n_deleted_files = dev->n_deleted_files;
+	cp->n_unlinked_files = dev->n_unlinked_files;
+	cp->n_bg_deletions = dev->n_bg_deletions;
+	cp->seq_number = dev->seq_number;
+
+}
+
+static void yaffs_checkpt_dev_to_dev(struct yaffs_dev *dev,
+				     struct yaffs_checkpt_dev *cp)
+{
+	dev->n_erased_blocks = cp->n_erased_blocks;
+	dev->alloc_block = cp->alloc_block;
+	dev->alloc_page = cp->alloc_page;
+	dev->n_free_chunks = cp->n_free_chunks;
+
+	dev->n_deleted_files = cp->n_deleted_files;
+	dev->n_unlinked_files = cp->n_unlinked_files;
+	dev->n_bg_deletions = cp->n_bg_deletions;
+	dev->seq_number = cp->seq_number;
+}
+
+static int yaffs2_wr_checkpt_dev(struct yaffs_dev *dev)
+{
+	struct yaffs_checkpt_dev cp;
+	u32 n_bytes;
+	u32 n_blocks =
+	    (dev->internal_end_block - dev->internal_start_block + 1);
+	int ok;
+
+	/* Write device runtime values */
+	yaffs2_dev_to_checkpt_dev(&cp, dev);
+	cp.struct_type = sizeof(cp);
+
+	ok = (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp));
+
+	/* Write block info */
+	if (ok) {
+		n_bytes = n_blocks * sizeof(struct yaffs_block_info);
+		ok = (yaffs2_checkpt_wr(dev, dev->block_info, n_bytes) ==
+		      n_bytes);
+	}
+
+	/* Write chunk bits */
+	if (ok) {
+		n_bytes = n_blocks * dev->chunk_bit_stride;
+		ok = (yaffs2_checkpt_wr(dev, dev->chunk_bits, n_bytes) ==
+		      n_bytes);
+	}
+	return ok ? 1 : 0;
+}
+
+static int yaffs2_rd_checkpt_dev(struct yaffs_dev *dev)
+{
+	struct yaffs_checkpt_dev cp;
+	u32 n_bytes;
+	u32 n_blocks =
+	    (dev->internal_end_block - dev->internal_start_block + 1);
+	int ok;
+
+	ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
+	if (!ok)
+		return 0;
+
+	if (cp.struct_type != sizeof(cp))
+		return 0;
+
+	yaffs_checkpt_dev_to_dev(dev, &cp);
+
+	n_bytes = n_blocks * sizeof(struct yaffs_block_info);
+
+	ok = (yaffs2_checkpt_rd(dev, dev->block_info, n_bytes) == n_bytes);
+
+	if (!ok)
+		return 0;
+	n_bytes = n_blocks * dev->chunk_bit_stride;
+
+	ok = (yaffs2_checkpt_rd(dev, dev->chunk_bits, n_bytes) == n_bytes);
+
+	return ok ? 1 : 0;
+}
+
+static void yaffs2_obj_checkpt_obj(struct yaffs_checkpt_obj *cp,
+				   struct yaffs_obj *obj)
+{
+	cp->obj_id = obj->obj_id;
+	cp->parent_id = (obj->parent) ? obj->parent->obj_id : 0;
+	cp->hdr_chunk = obj->hdr_chunk;
+	cp->variant_type = obj->variant_type;
+	cp->deleted = obj->deleted;
+	cp->soft_del = obj->soft_del;
+	cp->unlinked = obj->unlinked;
+	cp->fake = obj->fake;
+	cp->rename_allowed = obj->rename_allowed;
+	cp->unlink_allowed = obj->unlink_allowed;
+	cp->serial = obj->serial;
+	cp->n_data_chunks = obj->n_data_chunks;
+
+	if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
+		cp->size_or_equiv_obj = obj->variant.file_variant.file_size;
+	else if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK)
+		cp->size_or_equiv_obj = obj->variant.hardlink_variant.equiv_id;
+}
+
+static int taffs2_checkpt_obj_to_obj(struct yaffs_obj *obj,
+				     struct yaffs_checkpt_obj *cp)
+{
+	struct yaffs_obj *parent;
+
+	if (obj->variant_type != cp->variant_type) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"Checkpoint read object %d type %d chunk %d does not match existing object type %d",
+			cp->obj_id, cp->variant_type, cp->hdr_chunk,
+			obj->variant_type);
+		return 0;
+	}
+
+	obj->obj_id = cp->obj_id;
+
+	if (cp->parent_id)
+		parent = yaffs_find_or_create_by_number(obj->my_dev,
+						cp->parent_id,
+						YAFFS_OBJECT_TYPE_DIRECTORY);
+	else
+		parent = NULL;
+
+	if (parent) {
+		if (parent->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"Checkpoint read object %d parent %d type %d chunk %d Parent type, %d, not directory",
+				cp->obj_id, cp->parent_id,
+				cp->variant_type, cp->hdr_chunk,
+				parent->variant_type);
+			return 0;
+		}
+		yaffs_add_obj_to_dir(parent, obj);
+	}
+
+	obj->hdr_chunk = cp->hdr_chunk;
+	obj->variant_type = cp->variant_type;
+	obj->deleted = cp->deleted;
+	obj->soft_del = cp->soft_del;
+	obj->unlinked = cp->unlinked;
+	obj->fake = cp->fake;
+	obj->rename_allowed = cp->rename_allowed;
+	obj->unlink_allowed = cp->unlink_allowed;
+	obj->serial = cp->serial;
+	obj->n_data_chunks = cp->n_data_chunks;
+
+	if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
+		obj->variant.file_variant.file_size = cp->size_or_equiv_obj;
+	else if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK)
+		obj->variant.hardlink_variant.equiv_id = cp->size_or_equiv_obj;
+
+	if (obj->hdr_chunk > 0)
+		obj->lazy_loaded = 1;
+	return 1;
+}
+
+static int yaffs2_checkpt_tnode_worker(struct yaffs_obj *in,
+				       struct yaffs_tnode *tn, u32 level,
+				       int chunk_offset)
+{
+	int i;
+	struct yaffs_dev *dev = in->my_dev;
+	int ok = 1;
+
+	if (tn) {
+		if (level > 0) {
+
+			for (i = 0; i < YAFFS_NTNODES_INTERNAL && ok; i++) {
+				if (tn->internal[i]) {
+					ok = yaffs2_checkpt_tnode_worker(in,
+						 tn->internal[i],
+						 level - 1,
+						 (chunk_offset <<
+						  YAFFS_TNODES_INTERNAL_BITS)
+						 + i);
+				}
+			}
+		} else if (level == 0) {
+			u32 base_offset =
+			    chunk_offset << YAFFS_TNODES_LEVEL0_BITS;
+			ok = (yaffs2_checkpt_wr
+			      (dev, &base_offset,
+			       sizeof(base_offset)) == sizeof(base_offset));
+			if (ok)
+				ok = (yaffs2_checkpt_wr
+				      (dev, tn,
+				       dev->tnode_size) == dev->tnode_size);
+		}
+	}
+
+	return ok;
+}
+
+static int yaffs2_wr_checkpt_tnodes(struct yaffs_obj *obj)
+{
+	u32 end_marker = ~0;
+	int ok = 1;
+
+	if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE) {
+		ok = yaffs2_checkpt_tnode_worker(obj,
+						 obj->variant.file_variant.top,
+						 obj->variant.file_variant.
+						 top_level, 0);
+		if (ok)
+			ok = (yaffs2_checkpt_wr
+			      (obj->my_dev, &end_marker,
+			       sizeof(end_marker)) == sizeof(end_marker));
+	}
+
+	return ok ? 1 : 0;
+}
+
+static int yaffs2_rd_checkpt_tnodes(struct yaffs_obj *obj)
+{
+	u32 base_chunk;
+	int ok = 1;
+	struct yaffs_dev *dev = obj->my_dev;
+	struct yaffs_file_var *file_stuct_ptr = &obj->variant.file_variant;
+	struct yaffs_tnode *tn;
+	int nread = 0;
+
+	ok = (yaffs2_checkpt_rd(dev, &base_chunk, sizeof(base_chunk)) ==
+	      sizeof(base_chunk));
+
+	while (ok && (~base_chunk)) {
+		nread++;
+		/* Read level 0 tnode */
+
+		tn = yaffs_get_tnode(dev);
+		if (tn)
+			ok = (yaffs2_checkpt_rd(dev, tn, dev->tnode_size) ==
+				dev->tnode_size);
+		else
+			ok = 0;
+
+		if (tn && ok)
+			ok = yaffs_add_find_tnode_0(dev,
+						    file_stuct_ptr,
+						    base_chunk, tn) ? 1 : 0;
+
+		if (ok)
+			ok = (yaffs2_checkpt_rd
+			      (dev, &base_chunk,
+			       sizeof(base_chunk)) == sizeof(base_chunk));
+	}
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"Checkpoint read tnodes %d records, last %d. ok %d",
+		nread, base_chunk, ok);
+
+	return ok ? 1 : 0;
+}
+
+static int yaffs2_wr_checkpt_objs(struct yaffs_dev *dev)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_checkpt_obj cp;
+	int i;
+	int ok = 1;
+	struct list_head *lh;
+
+	/* Iterate through the objects in each hash entry,
+	 * dumping them to the checkpointing stream.
+	 */
+
+	for (i = 0; ok && i < YAFFS_NOBJECT_BUCKETS; i++) {
+		list_for_each(lh, &dev->obj_bucket[i].list) {
+			obj = list_entry(lh, struct yaffs_obj, hash_link);
+			if (!obj->defered_free) {
+				yaffs2_obj_checkpt_obj(&cp, obj);
+				cp.struct_type = sizeof(cp);
+
+				yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+					"Checkpoint write object %d parent %d type %d chunk %d obj addr %p",
+					cp.obj_id, cp.parent_id,
+					cp.variant_type, cp.hdr_chunk, obj);
+
+				ok = (yaffs2_checkpt_wr(dev, &cp,
+						sizeof(cp)) == sizeof(cp));
+
+				if (ok &&
+					obj->variant_type ==
+					YAFFS_OBJECT_TYPE_FILE)
+					ok = yaffs2_wr_checkpt_tnodes(obj);
+			}
+		}
+	}
+
+	/* Dump end of list */
+	memset(&cp, 0xFF, sizeof(struct yaffs_checkpt_obj));
+	cp.struct_type = sizeof(cp);
+
+	if (ok)
+		ok = (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp));
+
+	return ok ? 1 : 0;
+}
+
+static int yaffs2_rd_checkpt_objs(struct yaffs_dev *dev)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_checkpt_obj cp;
+	int ok = 1;
+	int done = 0;
+	struct yaffs_obj *hard_list = NULL;
+
+	while (ok && !done) {
+		ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
+		if (cp.struct_type != sizeof(cp)) {
+			yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+				"struct size %d instead of %d ok %d",
+				cp.struct_type, (int)sizeof(cp), ok);
+			ok = 0;
+		}
+
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"Checkpoint read object %d parent %d type %d chunk %d ",
+			cp.obj_id, cp.parent_id, cp.variant_type,
+			cp.hdr_chunk);
+
+		if (ok && cp.obj_id == ~0) {
+			done = 1;
+		} else if (ok) {
+			obj =
+			    yaffs_find_or_create_by_number(dev, cp.obj_id,
+							   cp.variant_type);
+			if (obj) {
+				ok = taffs2_checkpt_obj_to_obj(obj, &cp);
+				if (!ok)
+					break;
+				if (obj->variant_type ==
+					YAFFS_OBJECT_TYPE_FILE) {
+					ok = yaffs2_rd_checkpt_tnodes(obj);
+				} else if (obj->variant_type ==
+					YAFFS_OBJECT_TYPE_HARDLINK) {
+					obj->hard_links.next =
+					    (struct list_head *)hard_list;
+					hard_list = obj;
+				}
+			} else {
+				ok = 0;
+			}
+		}
+	}
+
+	if (ok)
+		yaffs_link_fixup(dev, hard_list);
+
+	return ok ? 1 : 0;
+}
+
+static int yaffs2_wr_checkpt_sum(struct yaffs_dev *dev)
+{
+	u32 checkpt_sum;
+	int ok;
+
+	yaffs2_get_checkpt_sum(dev, &checkpt_sum);
+
+	ok = (yaffs2_checkpt_wr(dev, &checkpt_sum, sizeof(checkpt_sum)) ==
+		sizeof(checkpt_sum));
+
+	if (!ok)
+		return 0;
+
+	return 1;
+}
+
+static int yaffs2_rd_checkpt_sum(struct yaffs_dev *dev)
+{
+	u32 checkpt_sum0;
+	u32 checkpt_sum1;
+	int ok;
+
+	yaffs2_get_checkpt_sum(dev, &checkpt_sum0);
+
+	ok = (yaffs2_checkpt_rd(dev, &checkpt_sum1, sizeof(checkpt_sum1)) ==
+		sizeof(checkpt_sum1));
+
+	if (!ok)
+		return 0;
+
+	if (checkpt_sum0 != checkpt_sum1)
+		return 0;
+
+	return 1;
+}
+
+static int yaffs2_wr_checkpt_data(struct yaffs_dev *dev)
+{
+	int ok = 1;
+
+	if (!yaffs2_checkpt_required(dev)) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"skipping checkpoint write");
+		ok = 0;
+	}
+
+	if (ok)
+		ok = yaffs2_checkpt_open(dev, 1);
+
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"write checkpoint validity");
+		ok = yaffs2_wr_checkpt_validity_marker(dev, 1);
+	}
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"write checkpoint device");
+		ok = yaffs2_wr_checkpt_dev(dev);
+	}
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"write checkpoint objects");
+		ok = yaffs2_wr_checkpt_objs(dev);
+	}
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"write checkpoint validity");
+		ok = yaffs2_wr_checkpt_validity_marker(dev, 0);
+	}
+
+	if (ok)
+		ok = yaffs2_wr_checkpt_sum(dev);
+
+	if (!yaffs_checkpt_close(dev))
+		ok = 0;
+
+	if (ok)
+		dev->is_checkpointed = 1;
+	else
+		dev->is_checkpointed = 0;
+
+	return dev->is_checkpointed;
+}
+
+static int yaffs2_rd_checkpt_data(struct yaffs_dev *dev)
+{
+	int ok = 1;
+
+	if (!dev->param.is_yaffs2)
+		ok = 0;
+
+	if (ok && dev->param.skip_checkpt_rd) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"skipping checkpoint read");
+		ok = 0;
+	}
+
+	if (ok)
+		ok = yaffs2_checkpt_open(dev, 0); /* open for read */
+
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"read checkpoint validity");
+		ok = yaffs2_rd_checkpt_validity_marker(dev, 1);
+	}
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"read checkpoint device");
+		ok = yaffs2_rd_checkpt_dev(dev);
+	}
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"read checkpoint objects");
+		ok = yaffs2_rd_checkpt_objs(dev);
+	}
+	if (ok) {
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"read checkpoint validity");
+		ok = yaffs2_rd_checkpt_validity_marker(dev, 0);
+	}
+
+	if (ok) {
+		ok = yaffs2_rd_checkpt_sum(dev);
+		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+			"read checkpoint checksum %d", ok);
+	}
+
+	if (!yaffs_checkpt_close(dev))
+		ok = 0;
+
+	if (ok)
+		dev->is_checkpointed = 1;
+	else
+		dev->is_checkpointed = 0;
+
+	return ok ? 1 : 0;
+}
+
+void yaffs2_checkpt_invalidate(struct yaffs_dev *dev)
+{
+	if (dev->is_checkpointed || dev->blocks_in_checkpt > 0) {
+		dev->is_checkpointed = 0;
+		yaffs2_checkpt_invalidate_stream(dev);
+	}
+	if (dev->param.sb_dirty_fn)
+		dev->param.sb_dirty_fn(dev);
+}
+
+int yaffs_checkpoint_save(struct yaffs_dev *dev)
+{
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"save entry: is_checkpointed %d",
+		dev->is_checkpointed);
+
+	yaffs_verify_objects(dev);
+	yaffs_verify_blocks(dev);
+	yaffs_verify_free_chunks(dev);
+
+	if (!dev->is_checkpointed) {
+		yaffs2_checkpt_invalidate(dev);
+		yaffs2_wr_checkpt_data(dev);
+	}
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT | YAFFS_TRACE_MOUNT,
+		"save exit: is_checkpointed %d",
+		dev->is_checkpointed);
+
+	return dev->is_checkpointed;
+}
+
+int yaffs2_checkpt_restore(struct yaffs_dev *dev)
+{
+	int retval;
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"restore entry: is_checkpointed %d",
+		dev->is_checkpointed);
+
+	retval = yaffs2_rd_checkpt_data(dev);
+
+	if (dev->is_checkpointed) {
+		yaffs_verify_objects(dev);
+		yaffs_verify_blocks(dev);
+		yaffs_verify_free_chunks(dev);
+	}
+
+	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
+		"restore exit: is_checkpointed %d",
+		dev->is_checkpointed);
+
+	return retval;
+}
+
+int yaffs2_handle_hole(struct yaffs_obj *obj, loff_t new_size)
+{
+	/* if new_size > old_file_size.
+	 * We're going to be writing a hole.
+	 * If the hole is small then write zeros otherwise write a start
+	 * of hole marker.
+	 */
+	loff_t old_file_size;
+	int increase;
+	int small_hole;
+	int result = YAFFS_OK;
+	struct yaffs_dev *dev = NULL;
+	u8 *local_buffer = NULL;
+	int small_increase_ok = 0;
+
+	if (!obj)
+		return YAFFS_FAIL;
+
+	if (obj->variant_type != YAFFS_OBJECT_TYPE_FILE)
+		return YAFFS_FAIL;
+
+	dev = obj->my_dev;
+
+	/* Bail out if not yaffs2 mode */
+	if (!dev->param.is_yaffs2)
+		return YAFFS_OK;
+
+	old_file_size = obj->variant.file_variant.file_size;
+
+	if (new_size <= old_file_size)
+		return YAFFS_OK;
+
+	increase = new_size - old_file_size;
+
+	if (increase < YAFFS_SMALL_HOLE_THRESHOLD * dev->data_bytes_per_chunk &&
+	    yaffs_check_alloc_available(dev, YAFFS_SMALL_HOLE_THRESHOLD + 1))
+		small_hole = 1;
+	else
+		small_hole = 0;
+
+	if (small_hole)
+		local_buffer = yaffs_get_temp_buffer(dev, __LINE__);
+
+	if (local_buffer) {
+		/* fill hole with zero bytes */
+		int pos = old_file_size;
+		int this_write;
+		int written;
+		memset(local_buffer, 0, dev->data_bytes_per_chunk);
+		small_increase_ok = 1;
+
+		while (increase > 0 && small_increase_ok) {
+			this_write = increase;
+			if (this_write > dev->data_bytes_per_chunk)
+				this_write = dev->data_bytes_per_chunk;
+			written =
+			    yaffs_do_file_wr(obj, local_buffer, pos, this_write,
+					     0);
+			if (written == this_write) {
+				pos += this_write;
+				increase -= this_write;
+			} else {
+				small_increase_ok = 0;
+			}
+		}
+
+		yaffs_release_temp_buffer(dev, local_buffer, __LINE__);
+
+		/* If out of space then reverse any chunks we've added */
+		if (!small_increase_ok)
+			yaffs_resize_file_down(obj, old_file_size);
+	}
+
+	if (!small_increase_ok &&
+	    obj->parent &&
+	    obj->parent->obj_id != YAFFS_OBJECTID_UNLINKED &&
+	    obj->parent->obj_id != YAFFS_OBJECTID_DELETED) {
+		/* Write a hole start header with the old file size */
+		yaffs_update_oh(obj, NULL, 0, 1, 0, NULL);
+	}
+
+	return result;
+}
+
+struct yaffs_block_index {
+	int seq;
+	int block;
+};
+
+static int yaffs2_ybicmp(const void *a, const void *b)
+{
+	int aseq = ((struct yaffs_block_index *)a)->seq;
+	int bseq = ((struct yaffs_block_index *)b)->seq;
+	int ablock = ((struct yaffs_block_index *)a)->block;
+	int bblock = ((struct yaffs_block_index *)b)->block;
+
+	if (aseq == bseq)
+		return ablock - bblock;
+	else
+		return aseq - bseq;
+}
+
+static inline int yaffs2_scan_chunk(struct yaffs_dev *dev,
+		struct yaffs_block_info *bi,
+		int blk, int chunk_in_block,
+		int *found_chunks,
+		u8 *chunk_data,
+		struct yaffs_obj **hard_list)
+{
+	struct yaffs_obj_hdr *oh;
+	struct yaffs_obj *in;
+	struct yaffs_obj *parent;
+	int equiv_id;
+	int file_size;
+	int is_shrink;
+	int is_unlinked;
+	struct yaffs_ext_tags tags;
+	int result;
+	int alloc_failed = 0;
+	int chunk = blk * dev->param.chunks_per_block + chunk_in_block;
+	struct yaffs_file_var *file_var;
+	struct yaffs_hardlink_var *hl_var;
+	struct yaffs_symlink_var *sl_var;
+
+	result = yaffs_rd_chunk_tags_nand(dev, chunk, NULL, &tags);
+
+	/* Let's have a good look at this chunk... */
+
+	if (!tags.chunk_used) {
+		/* An unassigned chunk in the block.
+		 * If there are used chunks after this one, then
+		 * it is a chunk that was skipped due to failing
+		 * the erased check. Just skip it so that it can
+		 * be deleted.
+		 * But, more typically, We get here when this is
+		 * an unallocated chunk and his means that
+		 * either the block is empty or this is the one
+		 * being allocated from
+		 */
+
+		if (*found_chunks) {
+			/* This is a chunk that was skipped due
+			 * to failing the erased check */
+		} else if (chunk_in_block == 0) {
+			/* We're looking at the first chunk in
+			 * the block so the block is unused */
+			bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
+			dev->n_erased_blocks++;
+		} else {
+			if (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCANNING
+			   || bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING) {
+				if (dev->seq_number == bi->seq_number) {
+					/* Allocating from this block*/
+					yaffs_trace(YAFFS_TRACE_SCAN,
+					    " Allocating from %d %d",
+					    blk, chunk_in_block);
+
+					bi->block_state =
+						YAFFS_BLOCK_STATE_ALLOCATING;
+					dev->alloc_block = blk;
+					dev->alloc_page = chunk_in_block;
+					dev->alloc_block_finder = blk;
+				} else {
+					/* This is a partially written block
+					 * that is not the current
+					 * allocation block.
+					 */
+					yaffs_trace(YAFFS_TRACE_SCAN,
+						"Partially written block %d detected. gc will fix this.",
+						blk);
+				}
+			}
+		}
+
+		dev->n_free_chunks++;
+
+	} else if (tags.ecc_result ==
+		YAFFS_ECC_RESULT_UNFIXED) {
+		yaffs_trace(YAFFS_TRACE_SCAN,
+			" Unfixed ECC in chunk(%d:%d), chunk ignored",
+			blk, chunk_in_block);
+			dev->n_free_chunks++;
+	} else if (tags.obj_id > YAFFS_MAX_OBJECT_ID ||
+		   tags.chunk_id > YAFFS_MAX_CHUNK_ID ||
+		   (tags.chunk_id > 0 &&
+		     tags.n_bytes > dev->data_bytes_per_chunk) ||
+		   tags.seq_number != bi->seq_number) {
+		yaffs_trace(YAFFS_TRACE_SCAN,
+			"Chunk (%d:%d) with bad tags:obj = %d, chunk_id = %d, n_bytes = %d, ignored",
+			blk, chunk_in_block, tags.obj_id,
+			tags.chunk_id, tags.n_bytes);
+		dev->n_free_chunks++;
+	} else if (tags.chunk_id > 0) {
+		/* chunk_id > 0 so it is a data chunk... */
+		unsigned int endpos;
+		u32 chunk_base = (tags.chunk_id - 1) *
+					dev->data_bytes_per_chunk;
+
+		*found_chunks = 1;
+
+		yaffs_set_chunk_bit(dev, blk, chunk_in_block);
+		bi->pages_in_use++;
+
+		in = yaffs_find_or_create_by_number(dev,
+					tags.obj_id,
+					YAFFS_OBJECT_TYPE_FILE);
+		if (!in)
+			/* Out of memory */
+			alloc_failed = 1;
+
+		if (in &&
+		    in->variant_type == YAFFS_OBJECT_TYPE_FILE &&
+		    chunk_base < in->variant.file_variant.shrink_size) {
+			/* This has not been invalidated by
+			 * a resize */
+			if (!yaffs_put_chunk_in_file(in, tags.chunk_id,
+								chunk, -1))
+				alloc_failed = 1;
+
+			/* File size is calculated by looking at
+			 * the data chunks if we have not
+			 * seen an object header yet.
+			 * Stop this practice once we find an
+			 * object header.
+			 */
+			endpos = chunk_base + tags.n_bytes;
+
+			if (!in->valid &&
+			    in->variant.file_variant.scanned_size < endpos) {
+				in->variant.file_variant.
+				    scanned_size = endpos;
+				in->variant.file_variant.
+				    file_size = endpos;
+			}
+		} else if (in) {
+			/* This chunk has been invalidated by a
+			 * resize, or a past file deletion
+			 * so delete the chunk*/
+			yaffs_chunk_del(dev, chunk, 1, __LINE__);
+		}
+	} else {
+		/* chunk_id == 0, so it is an ObjectHeader.
+		 * Thus, we read in the object header and make
+		 * the object
+		 */
+		*found_chunks = 1;
+
+		yaffs_set_chunk_bit(dev, blk, chunk_in_block);
+		bi->pages_in_use++;
+
+		oh = NULL;
+		in = NULL;
+
+		if (tags.extra_available) {
+			in = yaffs_find_or_create_by_number(dev,
+					tags.obj_id,
+					tags.extra_obj_type);
+			if (!in)
+				alloc_failed = 1;
+		}
+
+		if (!in ||
+		    (!in->valid && dev->param.disable_lazy_load)
+		    || tags.extra_shadows ||
+		    (!in->valid && (tags.obj_id ==
+				YAFFS_OBJECTID_ROOT
+				|| tags.obj_id ==
+				YAFFS_OBJECTID_LOSTNFOUND))) {
+
+			/* If we don't have  valid info then we
+			 * need to read the chunk
+			 * TODO In future we can probably defer
+			 * reading the chunk and living with
+			 * invalid data until needed.
+			 */
+
+			result = yaffs_rd_chunk_tags_nand(dev,
+						  chunk,
+						  chunk_data,
+						  NULL);
+
+			oh = (struct yaffs_obj_hdr *)chunk_data;
+
+			if (dev->param.inband_tags) {
+				/* Fix up the header if they got
+				 * corrupted by inband tags */
+				oh->shadows_obj =
+				    oh->inband_shadowed_obj_id;
+				oh->is_shrink =
+				    oh->inband_is_shrink;
+			}
+
+			if (!in) {
+				in = yaffs_find_or_create_by_number(dev,
+							tags.obj_id, oh->type);
+				if (!in)
+					alloc_failed = 1;
+			}
+		}
+
+		if (!in) {
+			/* TODO Hoosterman we have a problem! */
+			yaffs_trace(YAFFS_TRACE_ERROR,
+				"yaffs tragedy: Could not make object for object  %d at chunk %d during scan",
+				tags.obj_id, chunk);
+			return YAFFS_FAIL;
+		}
+
+		if (in->valid) {
+			/* We have already filled this one.
+			 * We have a duplicate that will be
+			 * discarded, but we first have to suck
+			 * out resize info if it is a file.
+			 */
+			if ((in->variant_type == YAFFS_OBJECT_TYPE_FILE) &&
+				((oh && oh->type == YAFFS_OBJECT_TYPE_FILE) ||
+				 (tags.extra_available &&
+				  tags.extra_obj_type == YAFFS_OBJECT_TYPE_FILE)
+				)) {
+				u32 this_size = (oh) ?
+					oh->file_size :
+					tags.extra_length;
+				u32 parent_obj_id = (oh) ?
+					oh->parent_obj_id :
+					tags.extra_parent_id;
+
+				is_shrink = (oh) ?
+					oh->is_shrink :
+					tags.extra_is_shrink;
+
+				/* If it is deleted (unlinked
+				 * at start also means deleted)
+				 * we treat the file size as
+				 * being zeroed at this point.
+				 */
+				if (parent_obj_id == YAFFS_OBJECTID_DELETED ||
+				    parent_obj_id == YAFFS_OBJECTID_UNLINKED) {
+					this_size = 0;
+					is_shrink = 1;
+				}
+
+				if (is_shrink &&
+				    in->variant.file_variant.shrink_size >
+				    this_size)
+					in->variant.file_variant.shrink_size =
+					this_size;
+
+				if (is_shrink)
+					bi->has_shrink_hdr = 1;
+			}
+			/* Use existing - destroy this one. */
+			yaffs_chunk_del(dev, chunk, 1, __LINE__);
+		}
+
+		if (!in->valid && in->variant_type !=
+		    (oh ? oh->type : tags.extra_obj_type))
+			yaffs_trace(YAFFS_TRACE_ERROR,
+				"yaffs tragedy: Bad object type, %d != %d, for object %d at chunk %d during scan",
+				oh ? oh->type : tags.extra_obj_type,
+				in->variant_type, tags.obj_id,
+				chunk);
+
+		if (!in->valid &&
+		    (tags.obj_id == YAFFS_OBJECTID_ROOT ||
+		     tags.obj_id == YAFFS_OBJECTID_LOSTNFOUND)) {
+			/* We only load some info, don't fiddle
+			 * with directory structure */
+			in->valid = 1;
+
+			if (oh) {
+				in->yst_mode = oh->yst_mode;
+				yaffs_load_attribs(in, oh);
+				in->lazy_loaded = 0;
+			} else {
+				in->lazy_loaded = 1;
+			}
+			in->hdr_chunk = chunk;
+
+		} else if (!in->valid) {
+			/* we need to load this info */
+			in->valid = 1;
+			in->hdr_chunk = chunk;
+			if (oh) {
+				in->variant_type = oh->type;
+				in->yst_mode = oh->yst_mode;
+				yaffs_load_attribs(in, oh);
+
+				if (oh->shadows_obj > 0)
+					yaffs_handle_shadowed_obj(dev,
+					     oh->shadows_obj, 1);
+
+				yaffs_set_obj_name_from_oh(in, oh);
+				parent = yaffs_find_or_create_by_number(dev,
+						oh->parent_obj_id,
+						YAFFS_OBJECT_TYPE_DIRECTORY);
+				file_size = oh->file_size;
+				is_shrink = oh->is_shrink;
+				equiv_id = oh->equiv_id;
+			} else {
+				in->variant_type = tags.extra_obj_type;
+				parent = yaffs_find_or_create_by_number(dev,
+						tags.extra_parent_id,
+						YAFFS_OBJECT_TYPE_DIRECTORY);
+				file_size = tags.extra_length;
+				is_shrink = tags.extra_is_shrink;
+				equiv_id = tags.extra_equiv_id;
+				in->lazy_loaded = 1;
+			}
+			in->dirty = 0;
+
+			if (!parent)
+				alloc_failed = 1;
+
+			/* directory stuff...
+			 * hook up to parent
+			 */
+
+			if (parent &&
+			    parent->variant_type == YAFFS_OBJECT_TYPE_UNKNOWN) {
+				/* Set up as a directory */
+				parent->variant_type =
+					YAFFS_OBJECT_TYPE_DIRECTORY;
+				INIT_LIST_HEAD(&parent->
+						variant.dir_variant.children);
+			} else if (!parent ||
+				   parent->variant_type !=
+					YAFFS_OBJECT_TYPE_DIRECTORY) {
+				/* Hoosterman, another problem....
+				 * Trying to use a non-directory as a directory
+				 */
+
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"yaffs tragedy: attempting to use non-directory as a directory in scan. Put in lost+found."
+					);
+				parent = dev->lost_n_found;
+			}
+			yaffs_add_obj_to_dir(parent, in);
+
+			is_unlinked = (parent == dev->del_dir) ||
+					(parent == dev->unlinked_dir);
+
+			if (is_shrink)
+				/* Mark the block */
+				bi->has_shrink_hdr = 1;
+
+			/* Note re hardlinks.
+			 * Since we might scan a hardlink before its equivalent
+			 * object is scanned we put them all in a list.
+			 * After scanning is complete, we should have all the
+			 * objects, so we run through this list and fix up all
+			 * the chains.
+			 */
+
+			switch (in->variant_type) {
+			case YAFFS_OBJECT_TYPE_UNKNOWN:
+				/* Todo got a problem */
+				break;
+			case YAFFS_OBJECT_TYPE_FILE:
+				file_var = &in->variant.file_variant;
+				if (file_var->scanned_size < file_size) {
+					/* This covers the case where the file
+					 * size is greater than the data held.
+					 * This will happen if the file is
+					 * resized to be larger than its
+					 * current data extents.
+					 */
+					file_var->file_size = file_size;
+					file_var->scanned_size = file_size;
+				}
+
+				if (file_var->shrink_size > file_size)
+					file_var->shrink_size = file_size;
+
+				break;
+			case YAFFS_OBJECT_TYPE_HARDLINK:
+				hl_var = &in->variant.hardlink_variant;
+				if (!is_unlinked) {
+					hl_var->equiv_id = equiv_id;
+					in->hard_links.next =
+					    (struct list_head *) *hard_list;
+					*hard_list = in;
+				}
+				break;
+			case YAFFS_OBJECT_TYPE_DIRECTORY:
+				/* Do nothing */
+				break;
+			case YAFFS_OBJECT_TYPE_SPECIAL:
+				/* Do nothing */
+				break;
+			case YAFFS_OBJECT_TYPE_SYMLINK:
+				sl_var = &in->variant.symlink_variant;
+				if (oh) {
+					sl_var->alias =
+					    yaffs_clone_str(oh->alias);
+					if (!sl_var->alias)
+						alloc_failed = 1;
+				}
+				break;
+			}
+		}
+	}
+	return alloc_failed ? YAFFS_FAIL : YAFFS_OK;
+}
+
+int yaffs2_scan_backwards(struct yaffs_dev *dev)
+{
+	int blk;
+	int block_iter;
+	int start_iter;
+	int end_iter;
+	int n_to_scan = 0;
+	enum yaffs_block_state state;
+	int c;
+	int deleted;
+	struct yaffs_obj *hard_list = NULL;
+	struct yaffs_block_info *bi;
+	u32 seq_number;
+	int n_blocks = dev->internal_end_block - dev->internal_start_block + 1;
+	u8 *chunk_data;
+	int found_chunks;
+	int alloc_failed = 0;
+	struct yaffs_block_index *block_index = NULL;
+	int alt_block_index = 0;
+
+	yaffs_trace(YAFFS_TRACE_SCAN,
+		"yaffs2_scan_backwards starts  intstartblk %d intendblk %d...",
+		dev->internal_start_block, dev->internal_end_block);
+
+	dev->seq_number = YAFFS_LOWEST_SEQUENCE_NUMBER;
+
+	block_index = kmalloc(n_blocks * sizeof(struct yaffs_block_index),
+			GFP_NOFS);
+
+	if (!block_index) {
+		block_index =
+		    vmalloc(n_blocks * sizeof(struct yaffs_block_index));
+		alt_block_index = 1;
+	}
+
+	if (!block_index) {
+		yaffs_trace(YAFFS_TRACE_SCAN,
+			"yaffs2_scan_backwards() could not allocate block index!"
+			);
+		return YAFFS_FAIL;
+	}
+
+	dev->blocks_in_checkpt = 0;
+
+	chunk_data = yaffs_get_temp_buffer(dev, __LINE__);
+
+	/* Scan all the blocks to determine their state */
+	bi = dev->block_info;
+	for (blk = dev->internal_start_block; blk <= dev->internal_end_block;
+	     blk++) {
+		yaffs_clear_chunk_bits(dev, blk);
+		bi->pages_in_use = 0;
+		bi->soft_del_pages = 0;
+
+		yaffs_query_init_block_state(dev, blk, &state, &seq_number);
+
+		bi->block_state = state;
+		bi->seq_number = seq_number;
+
+		if (bi->seq_number == YAFFS_SEQUENCE_CHECKPOINT_DATA)
+			bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
+		if (bi->seq_number == YAFFS_SEQUENCE_BAD_BLOCK)
+			bi->block_state = YAFFS_BLOCK_STATE_DEAD;
+
+		yaffs_trace(YAFFS_TRACE_SCAN_DEBUG,
+			"Block scanning block %d state %d seq %d",
+			blk, bi->block_state, seq_number);
+
+		if (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT) {
+			dev->blocks_in_checkpt++;
+
+		} else if (bi->block_state == YAFFS_BLOCK_STATE_DEAD) {
+			yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
+				"block %d is bad", blk);
+		} else if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
+			yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "Block empty ");
+			dev->n_erased_blocks++;
+			dev->n_free_chunks += dev->param.chunks_per_block;
+		} else if (bi->block_state ==
+				YAFFS_BLOCK_STATE_NEEDS_SCANNING) {
+			/* Determine the highest sequence number */
+			if (seq_number >= YAFFS_LOWEST_SEQUENCE_NUMBER &&
+			    seq_number < YAFFS_HIGHEST_SEQUENCE_NUMBER) {
+				block_index[n_to_scan].seq = seq_number;
+				block_index[n_to_scan].block = blk;
+				n_to_scan++;
+				if (seq_number >= dev->seq_number)
+					dev->seq_number = seq_number;
+			} else {
+				/* TODO: Nasty sequence number! */
+				yaffs_trace(YAFFS_TRACE_SCAN,
+					"Block scanning block %d has bad sequence number %d",
+					blk, seq_number);
+			}
+		}
+		bi++;
+	}
+
+	yaffs_trace(YAFFS_TRACE_SCAN, "%d blocks to be sorted...", n_to_scan);
+
+	cond_resched();
+
+	/* Sort the blocks by sequence number */
+	sort(block_index, n_to_scan, sizeof(struct yaffs_block_index),
+		   yaffs2_ybicmp, NULL);
+
+	cond_resched();
+
+	yaffs_trace(YAFFS_TRACE_SCAN, "...done");
+
+	/* Now scan the blocks looking at the data. */
+	start_iter = 0;
+	end_iter = n_to_scan - 1;
+	yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "%d blocks to scan", n_to_scan);
+
+	/* For each block.... backwards */
+	for (block_iter = end_iter; !alloc_failed && block_iter >= start_iter;
+	     block_iter--) {
+		/* Cooperative multitasking! This loop can run for so
+		   long that watchdog timers expire. */
+		cond_resched();
+
+		/* get the block to scan in the correct order */
+		blk = block_index[block_iter].block;
+		bi = yaffs_get_block_info(dev, blk);
+		deleted = 0;
+
+		/* For each chunk in each block that needs scanning.... */
+		found_chunks = 0;
+		for (c = dev->param.chunks_per_block - 1;
+		     !alloc_failed && c >= 0 &&
+		     (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCANNING ||
+		      bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING); c--) {
+			/* Scan backwards...
+			 * Read the tags and decide what to do
+			 */
+			if (yaffs2_scan_chunk(dev, bi, blk, c,
+					&found_chunks, chunk_data,
+					&hard_list) ==
+				YAFFS_FAIL)
+				alloc_failed = 1;
+		}
+
+		if (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCANNING) {
+			/* If we got this far while scanning, then the block
+			 * is fully allocated. */
+			bi->block_state = YAFFS_BLOCK_STATE_FULL;
+		}
+
+		/* Now let's see if it was dirty */
+		if (bi->pages_in_use == 0 &&
+		    !bi->has_shrink_hdr &&
+		    bi->block_state == YAFFS_BLOCK_STATE_FULL) {
+			yaffs_block_became_dirty(dev, blk);
+		}
+	}
+
+	yaffs_skip_rest_of_block(dev);
+
+	if (alt_block_index)
+		vfree(block_index);
+	else
+		kfree(block_index);
+
+	/* Ok, we've done all the scanning.
+	 * Fix up the hard link chains.
+	 * We have scanned all the objects, now it's time to add these
+	 * hardlinks.
+	 */
+	yaffs_link_fixup(dev, hard_list);
+
+	yaffs_release_temp_buffer(dev, chunk_data, __LINE__);
+
+	if (alloc_failed)
+		return YAFFS_FAIL;
+
+	yaffs_trace(YAFFS_TRACE_SCAN, "yaffs2_scan_backwards ends");
+
+	return YAFFS_OK;
+}
diff --git a/fs/yaffs2/yaffs_yaffs2.h b/fs/yaffs2/yaffs_yaffs2.h
new file mode 100644
index 0000000..e1a9287
--- /dev/null
+++ b/fs/yaffs2/yaffs_yaffs2.h
@@ -0,0 +1,39 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_YAFFS2_H__
+#define __YAFFS_YAFFS2_H__
+
+#include "yaffs_guts.h"
+
+void yaffs_calc_oldest_dirty_seq(struct yaffs_dev *dev);
+void yaffs2_find_oldest_dirty_seq(struct yaffs_dev *dev);
+void yaffs2_clear_oldest_dirty_seq(struct yaffs_dev *dev,
+				   struct yaffs_block_info *bi);
+void yaffs2_update_oldest_dirty_seq(struct yaffs_dev *dev, unsigned block_no,
+				    struct yaffs_block_info *bi);
+int yaffs_block_ok_for_gc(struct yaffs_dev *dev, struct yaffs_block_info *bi);
+u32 yaffs2_find_refresh_block(struct yaffs_dev *dev);
+int yaffs2_checkpt_required(struct yaffs_dev *dev);
+int yaffs_calc_checkpt_blocks_required(struct yaffs_dev *dev);
+
+void yaffs2_checkpt_invalidate(struct yaffs_dev *dev);
+int yaffs2_checkpt_save(struct yaffs_dev *dev);
+int yaffs2_checkpt_restore(struct yaffs_dev *dev);
+
+int yaffs2_handle_hole(struct yaffs_obj *obj, loff_t new_size);
+int yaffs2_scan_backwards(struct yaffs_dev *dev);
+
+#endif
-- 
1.7.1

Re: [PATCH 07/10] Add yaffs2 file system: yaffs1 and yaffs2 mode specific code

[Ryan Mallon]

On 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

More comments below.

~Ryan

> ---
>  fs/yaffs2/yaffs_yaffs1.c |  423 +++++++++++++
>  fs/yaffs2/yaffs_yaffs1.h |   22 +
>  fs/yaffs2/yaffs_yaffs2.c | 1516 ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yaffs_yaffs2.h |   39 ++
>  4 files changed, 2000 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_yaffs1.c
>  create mode 100644 fs/yaffs2/yaffs_yaffs1.h
>  create mode 100644 fs/yaffs2/yaffs_yaffs2.c
>  create mode 100644 fs/yaffs2/yaffs_yaffs2.h
> 
> diff --git a/fs/yaffs2/yaffs_yaffs1.c b/fs/yaffs2/yaffs_yaffs1.c
> new file mode 100644
> index 0000000..6ee91a1
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_yaffs1.c
> @@ -0,0 +1,423 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_yaffs1.h"
> +#include "yportenv.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_bitmap.h"
> +#include "yaffs_getblockinfo.h"
> +#include "yaffs_nand.h"
> +#include "yaffs_attribs.h"
> +
> +int yaffs1_scan(struct yaffs_dev *dev)
> +{
> +	struct yaffs_ext_tags tags;
> +	int blk;
> +	int result;
> +	int chunk;
> +	int c;
> +	int deleted;

int blk, result, chunk, c, deleted;

etc, will save some lines.

> +	enum yaffs_block_state state;
> +	struct yaffs_obj *hard_list = NULL;
> +	struct yaffs_block_info *bi;
> +	u32 seq_number;
> +	struct yaffs_obj_hdr *oh;
> +	struct yaffs_obj *in;
> +	struct yaffs_obj *parent;
> +	int alloc_failed = 0;
> +	struct yaffs_shadow_fixer *shadow_fixers = NULL;
> +	u8 *chunk_data;
> +
> +	yaffs_trace(YAFFS_TRACE_SCAN,
> +		"yaffs1_scan starts  intstartblk %d intendblk %d...",
> +		dev->internal_start_block, dev->internal_end_block);
> +
> +	chunk_data = yaffs_get_temp_buffer(dev, __LINE__);
> +
> +	dev->seq_number = YAFFS_LOWEST_SEQUENCE_NUMBER;
> +
> +	/* Scan all the blocks to determine their state */
> +	bi = dev->block_info;
> +	for (blk = dev->internal_start_block; blk <= dev->internal_end_block;
> +	     blk++) {
> +		yaffs_clear_chunk_bits(dev, blk);
> +		bi->pages_in_use = 0;
> +		bi->soft_del_pages = 0;
> +
> +		yaffs_query_init_block_state(dev, blk, &state, &seq_number);
> +
> +		bi->block_state = state;
> +		bi->seq_number = seq_number;
> +
> +		if (bi->seq_number == YAFFS_SEQUENCE_BAD_BLOCK)
> +			bi->block_state = state = YAFFS_BLOCK_STATE_DEAD;
> +
> +		yaffs_trace(YAFFS_TRACE_SCAN_DEBUG,
> +			"Block scanning block %d state %d seq %d",
> +			blk, state, seq_number);
> +
> +		if (state == YAFFS_BLOCK_STATE_DEAD) {
> +			yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
> +				"block %d is bad", blk);
> +		} else if (state == YAFFS_BLOCK_STATE_EMPTY) {
> +			yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "Block empty ");
> +			dev->n_erased_blocks++;
> +			dev->n_free_chunks += dev->param.chunks_per_block;
> +		}
> +		bi++;
> +	}
> +
> +	/* For each block.... */
> +	for (blk = dev->internal_start_block;
> +	     !alloc_failed && blk <= dev->internal_end_block; blk++) {
> +
> +		cond_resched();
> +
> +		bi = yaffs_get_block_info(dev, blk);
> +		state = bi->block_state;
> +
> +		deleted = 0;
> +
> +		/* For each chunk in each block that needs scanning.... */
> +		for (c = 0; !alloc_failed && c < dev->param.chunks_per_block &&
> +		     state == YAFFS_BLOCK_STATE_NEEDS_SCANNING; c++) {

Maybe worth breaking parts of the body of this loop into sub functions
to reduce the indentation level and make everything a bit more readable.

> +			/* Read the tags and decide what to do */
> +			chunk = blk * dev->param.chunks_per_block + c;
> +
> +			result = yaffs_rd_chunk_tags_nand(dev, chunk, NULL,
> +							  &tags);
> +
> +			/* Let's have a good look at this chunk... */
> +
> +			if (tags.ecc_result == YAFFS_ECC_RESULT_UNFIXED
> +			    || tags.is_deleted) {
> +				/* YAFFS1 only...
> +				 * A deleted chunk
> +				 */
> +				deleted++;
> +				dev->n_free_chunks++;
> +			} else if (!tags.chunk_used) {
> +				/* An unassigned chunk in the block
> +				 * This means that either the block is empty or
> +				 * this is the one being allocated from
> +				 */
> +
> +				if (c == 0) {
> +					/* We're looking at the first chunk in
> +					 *the block so the block is unused */
> +					state = YAFFS_BLOCK_STATE_EMPTY;
> +					dev->n_erased_blocks++;
> +				} else {
> +					/* this is the block being allocated */
> +					yaffs_trace(YAFFS_TRACE_SCAN,
> +						" Allocating from %d %d",
> +						blk, c);
> +					state = YAFFS_BLOCK_STATE_ALLOCATING;
> +					dev->alloc_block = blk;
> +					dev->alloc_page = c;
> +					dev->alloc_block_finder = blk;
> +
> +				}
> +
> +				dev->n_free_chunks +=
> +				    (dev->param.chunks_per_block - c);
> +			} else if (tags.chunk_id > 0) {
> +				/* chunk_id > 0 so it is a data chunk... */
> +				unsigned int endpos;
> +
> +				yaffs_set_chunk_bit(dev, blk, c);
> +				bi->pages_in_use++;
> +
> +				in = yaffs_find_or_create_by_number(dev,
> +							tags.obj_id,
> +							YAFFS_OBJECT_TYPE_FILE);
> +				/* PutChunkIntoFile checks for a clash
> +				 * (two data chunks with the same chunk_id).
> +				 */
> +
> +				if (!in)
> +					alloc_failed = 1;
> +
> +				if (in) {
> +					if (!yaffs_put_chunk_in_file
> +					    (in, tags.chunk_id, chunk, 1))
> +						alloc_failed = 1;
> +				}

This looks like it could be simplified a little by replacing
'alloc_failed = 1' statement with a 'goto alloc_failed'. It means that
you don't have keep checking to make sure in is valid.

> +
> +				endpos =
> +				    (tags.chunk_id - 1) *
> +				    dev->data_bytes_per_chunk +
> +				    tags.n_bytes;
> +				if (in &&
> +				    in->variant_type ==
> +				    YAFFS_OBJECT_TYPE_FILE &&
> +				    in->variant.file_variant.scanned_size <
> +				    endpos) {
> +					in->variant.file_variant.scanned_size =
> +					    endpos;
> +					if (!dev->param.use_header_file_size) {
> +						in->variant.
> +						    file_variant.file_size =
> +						    in->variant.
> +						    file_variant.scanned_size;
> +					}
> +
> +				}
> +			} else {
> +				/* chunk_id == 0, so it is an ObjectHeader.
> +				 * Make the object
> +				 */
> +				yaffs_set_chunk_bit(dev, blk, c);
> +				bi->pages_in_use++;
> +
> +				result = yaffs_rd_chunk_tags_nand(dev, chunk,
> +								  chunk_data,
> +								  NULL);
> +
> +				oh = (struct yaffs_obj_hdr *)chunk_data;
> +
> +				in = yaffs_find_by_number(dev, tags.obj_id);
> +				if (in && in->variant_type != oh->type) {
> +					/* This should not happen, but somehow
> +					 * Wev'e ended up with an obj_id that
> +					 * has been reused but not yet deleted,
> +					 * and worse still it has changed type.
> +					 * Delete the old object.
> +					 */
> +
> +					yaffs_del_obj(in);
> +					in = NULL;

You don't need the assignment to NULL here.

> +				}
> +
> +				in = yaffs_find_or_create_by_number(dev,
> +								tags.obj_id,
> +								oh->type);
> +
> +				if (!in)
> +					alloc_failed = 1;
> +
> +				if (in && oh->shadows_obj > 0) {
> +
> +					struct yaffs_shadow_fixer *fixer;
> +					fixer =
> +						kmalloc(sizeof
> +						(struct yaffs_shadow_fixer),
> +						GFP_NOFS);

if (!fixer)? Do we want a warning?

Fixers could also use struct list_head rather than their own (albeit
simple) linked list implementation.

> +					if (fixer) {
> +						fixer->next = shadow_fixers;
> +						shadow_fixers = fixer;
> +						fixer->obj_id = tags.obj_id;
> +						fixer->shadowed_id =
> +						    oh->shadows_obj;
> +						yaffs_trace(YAFFS_TRACE_SCAN,
> +							" Shadow fixer: %d shadows %d",
> +							fixer->obj_id,
> +							fixer->shadowed_id);
> +
> +					}
> +
> +				}
> +
> +				if (in && in->valid) {
> +					/* We have already filled this one.
> +					 * We have a duplicate and need to
> +					 * resolve it. */
> +
> +					unsigned existing_serial = in->serial;
> +					unsigned new_serial =
> +					    tags.serial_number;
> +
> +					if (((existing_serial + 1) & 3) ==
> +					    new_serial) {
> +						/* Use new one - destroy the
> +						 * exisiting one */
> +						yaffs_chunk_del(dev,
> +								in->hdr_chunk,
> +								1, __LINE__);
> +						in->valid = 0;
> +					} else {
> +						/* Use existing - destroy
> +						 * this one. */
> +						yaffs_chunk_del(dev, chunk, 1,
> +								__LINE__);
> +					}
> +				}
> +
> +				if (in && !in->valid &&
> +				    (tags.obj_id == YAFFS_OBJECTID_ROOT ||
> +				     tags.obj_id ==
> +				     YAFFS_OBJECTID_LOSTNFOUND)) {
> +					/* We only load some info, don't fiddle
> +					 * with directory structure */
> +					in->valid = 1;
> +					in->variant_type = oh->type;
> +
> +					in->yst_mode = oh->yst_mode;
> +					yaffs_load_attribs(in, oh);
> +					in->hdr_chunk = chunk;
> +					in->serial = tags.serial_number;
> +
> +				} else if (in && !in->valid) {
> +					/* we need to load this info */
> +
> +					in->valid = 1;
> +					in->variant_type = oh->type;
> +
> +					in->yst_mode = oh->yst_mode;
> +					yaffs_load_attribs(in, oh);
> +					in->hdr_chunk = chunk;
> +					in->serial = tags.serial_number;
> +
> +					yaffs_set_obj_name_from_oh(in, oh);
> +					in->dirty = 0;
> +
> +					/* directory stuff...
> +					 * hook up to parent
> +					 */
> +
> +					parent =
> +					    yaffs_find_or_create_by_number
> +					    (dev, oh->parent_obj_id,
> +					     YAFFS_OBJECT_TYPE_DIRECTORY);
> +					if (!parent)
> +						alloc_failed = 1;

Again, using a goto to get out of the loop here will simplify the if
statements below.

> +					if (parent && parent->variant_type ==
> +					    YAFFS_OBJECT_TYPE_UNKNOWN) {
> +						/* Set up as a directory */
> +						parent->variant_type =
> +						    YAFFS_OBJECT_TYPE_DIRECTORY;
> +						INIT_LIST_HEAD(&parent->
> +							variant.dir_variant.
> +							children);
> +					} else if (!parent ||
> +						parent->variant_type !=
> +						YAFFS_OBJECT_TYPE_DIRECTORY) {
> +						/* Hoosterman, a problem....
> +						 * We're trying to use a
> +						 * non-directory as a directory
> +						 */

You can drop this comment, the yaffs_trace has the same information.

> +
> +						yaffs_trace(YAFFS_TRACE_ERROR,
> +							"yaffs tragedy: attempting to use non-directory as a directory in scan. Put in lost+found."
> +							);
> +						parent = dev->lost_n_found;
> +					}
> +
> +					yaffs_add_obj_to_dir(parent, in);
> +
> +					switch (in->variant_type) {
> +					case YAFFS_OBJECT_TYPE_UNKNOWN:
> +						/* Todo got a problem */

Warning?

> +						break;
> +					case YAFFS_OBJECT_TYPE_FILE:
> +						if (dev->param.
> +						    use_header_file_size)
> +
> +							in->variant.
> +							 file_variant.file_size
> +							    = oh->file_size;
> +
> +						break;
> +					case YAFFS_OBJECT_TYPE_HARDLINK:
> +						in->variant.
> +						    hardlink_variant.equiv_id =
> +						    oh->equiv_id;
> +						in->hard_links.next =
> +						    (struct list_head *)
> +						    hard_list;

More linked list casting weirdness?

> +						hard_list = in;
> +						break;
> +					case YAFFS_OBJECT_TYPE_DIRECTORY:
> +						/* Do nothing */
> +						break;
> +					case YAFFS_OBJECT_TYPE_SPECIAL:
> +						/* Do nothing */
> +						break;
> +					case YAFFS_OBJECT_TYPE_SYMLINK:
> +						in->variant.symlink_variant.
> +						    alias =
> +						    yaffs_clone_str(oh->alias);
> +						if (!in->variant.
> +						    symlink_variant.alias)
> +							alloc_failed = 1;
> +						break;
> +					}
> +				}
> +			}
> +		}
> +
> +		if (state == YAFFS_BLOCK_STATE_NEEDS_SCANNING) {
> +			/* If we got this far while scanning,
> +			 * then the block is fully allocated. */
> +			state = YAFFS_BLOCK_STATE_FULL;
> +		}
> +
> +		if (state == YAFFS_BLOCK_STATE_ALLOCATING) {
> +			/* If the block was partially allocated then
> +			 * treat it as fully allocated. */
> +			state = YAFFS_BLOCK_STATE_FULL;
> +			dev->alloc_block = -1;
> +		}
> +
> +		bi->block_state = state;
> +
> +		/* Now let's see if it was dirty */
> +		if (bi->pages_in_use == 0 &&
> +		    !bi->has_shrink_hdr &&
> +		    bi->block_state == YAFFS_BLOCK_STATE_FULL) {
> +			yaffs_block_became_dirty(dev, blk);
> +		}
> +	}
> +
> +	/* Ok, we've done all the scanning.
> +	 * Fix up the hard link chains.
> +	 * We should now have scanned all the objects, now it's time to add
> +	 * these hardlinks.
> +	 */
> +
> +	yaffs_link_fixup(dev, hard_list);
> +
> +	/* Fix up any shadowed objects */
> +	{
> +		struct yaffs_shadow_fixer *fixer;
> +		struct yaffs_obj *obj;

Move these to the top of the function (or reuse existing ones) and
remove a level of indentation :-)

> +
> +		while (shadow_fixers) {
> +			fixer = shadow_fixers;
> +			shadow_fixers = fixer->next;
> +			/* Complete the rename transaction by deleting the
> +			 * shadowed object then setting the object header
> +			 to unshadowed.
> +			 */
> +			obj = yaffs_find_by_number(dev, fixer->shadowed_id);
> +			if (obj)
> +				yaffs_del_obj(obj);
> +
> +			obj = yaffs_find_by_number(dev, fixer->obj_id);
> +
> +			if (obj)
> +				yaffs_update_oh(obj, NULL, 1, 0, 0, NULL);
> +
> +			kfree(fixer);
> +		}
> +	}
> +
> +	yaffs_release_temp_buffer(dev, chunk_data, __LINE__);
> +
> +	if (alloc_failed)
> +		return YAFFS_FAIL;
> +
> +	yaffs_trace(YAFFS_TRACE_SCAN, "yaffs1_scan ends");
> +
> +	return YAFFS_OK;
> +}
> diff --git a/fs/yaffs2/yaffs_yaffs1.h b/fs/yaffs2/yaffs_yaffs1.h
> new file mode 100644
> index 0000000..db23e04
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_yaffs1.h
> @@ -0,0 +1,22 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_YAFFS1_H__
> +#define __YAFFS_YAFFS1_H__
> +
> +#include "yaffs_guts.h"
> +int yaffs1_scan(struct yaffs_dev *dev);
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_yaffs2.c b/fs/yaffs2/yaffs_yaffs2.c
> new file mode 100644
> index 0000000..77101e7
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_yaffs2.c
> @@ -0,0 +1,1516 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include "yaffs_guts.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_yaffs2.h"
> +#include "yaffs_checkptrw.h"
> +#include "yaffs_bitmap.h"
> +#include "yaffs_nand.h"
> +#include "yaffs_getblockinfo.h"
> +#include "yaffs_verify.h"
> +#include "yaffs_attribs.h"
> +
> +/*
> + * Checkpoints are really no benefit on very small partitions.
> + *
> + * To save space on small partitions don't bother with checkpoints unless
> + * the partition is at least this big.
> + */
> +#define YAFFS_CHECKPOINT_MIN_BLOCKS 60
> +#define YAFFS_SMALL_HOLE_THRESHOLD 4
> +
> +/*
> + * Oldest Dirty Sequence Number handling.
> + */
> +
> +/* yaffs_calc_oldest_dirty_seq()
> + * yaffs2_find_oldest_dirty_seq()
> + * Calculate the oldest dirty sequence number if we don't know it.
> + */
> +void yaffs_calc_oldest_dirty_seq(struct yaffs_dev *dev)
> +{
> +	int i;
> +	unsigned seq;
> +	unsigned block_no = 0;
> +	struct yaffs_block_info *b;
> +
> +	if (!dev->param.is_yaffs2)
> +		return;
> +
> +	/* Find the oldest dirty sequence number. */
> +	seq = dev->seq_number + 1;
> +	b = dev->block_info;
> +	for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
> +		if (b->block_state == YAFFS_BLOCK_STATE_FULL &&
> +		    (b->pages_in_use - b->soft_del_pages) <
> +		    dev->param.chunks_per_block && b->seq_number < seq) {
> +			seq = b->seq_number;
> +			block_no = i;
> +		}
> +		b++;
> +	}
> +
> +	if (block_no) {
> +		dev->oldest_dirty_seq = seq;
> +		dev->oldest_dirty_block = block_no;
> +	}
> +}
> +
> +void yaffs2_find_oldest_dirty_seq(struct yaffs_dev *dev)
> +{
> +	if (!dev->param.is_yaffs2)
> +		return;
> +
> +	if (!dev->oldest_dirty_seq)
> +		yaffs_calc_oldest_dirty_seq(dev);

if (dev->param.is_yaffs2 && !dev->oldest_dirty_seq)
	yaffs_calc_oldest_dirty_seq(dev);

Similar reductions are possible for other functions. Also, can we
actually end up here if dev->param.is_yaffs2 is not set?

> +}
> +
> +/*
> + * yaffs_clear_oldest_dirty_seq()
> + * Called when a block is erased or marked bad. (ie. when its seq_number
> + * becomes invalid). If the value matches the oldest then we clear
> + * dev->oldest_dirty_seq to force its recomputation.
> + */
> +void yaffs2_clear_oldest_dirty_seq(struct yaffs_dev *dev,
> +				   struct yaffs_block_info *bi)
> +{
> +
> +	if (!dev->param.is_yaffs2)
> +		return;
> +
> +	if (!bi || bi->seq_number == dev->oldest_dirty_seq) {
> +		dev->oldest_dirty_seq = 0;
> +		dev->oldest_dirty_block = 0;
> +	}
> +}
> +
> +/*
> + * yaffs2_update_oldest_dirty_seq()
> + * Update the oldest dirty sequence number whenever we dirty a block.
> + * Only do this if the oldest_dirty_seq is actually being tracked.
> + */
> +void yaffs2_update_oldest_dirty_seq(struct yaffs_dev *dev, unsigned block_no,
> +				    struct yaffs_block_info *bi)
> +{
> +	if (!dev->param.is_yaffs2)
> +		return;
> +
> +	if (dev->oldest_dirty_seq) {
> +		if (dev->oldest_dirty_seq > bi->seq_number) {
> +			dev->oldest_dirty_seq = bi->seq_number;
> +			dev->oldest_dirty_block = block_no;
> +		}
> +	}
> +}
> +
> +int yaffs_block_ok_for_gc(struct yaffs_dev *dev, struct yaffs_block_info *bi)
> +{
> +
> +	if (!dev->param.is_yaffs2)
> +		return 1;	/* disqualification only applies to yaffs2. */
> +
> +	if (!bi->has_shrink_hdr)
> +		return 1;	/* can gc */
> +
> +	yaffs2_find_oldest_dirty_seq(dev);
> +
> +	/* Can't do gc of this block if there are any blocks older than this
> +	 * one that have discarded pages.
> +	 */
> +	return (bi->seq_number <= dev->oldest_dirty_seq);
> +}
> +
> +/*
> + * yaffs2_find_refresh_block()
> + * periodically finds the oldest full block by sequence number for refreshing.
> + * Only for yaffs2.
> + */
> +u32 yaffs2_find_refresh_block(struct yaffs_dev *dev)
> +{
> +	u32 b;
> +	u32 oldest = 0;
> +	u32 oldest_seq = 0;
> +	struct yaffs_block_info *bi;
> +
> +	if (!dev->param.is_yaffs2)
> +		return oldest;
> +
> +	/*
> +	 * If refresh period < 10 then refreshing is disabled.
> +	 */
> +	if (dev->param.refresh_period < 10)
> +		return oldest;
> +
> +	/*
> +	 * Fix broken values.
> +	 */
> +	if (dev->refresh_skip > dev->param.refresh_period)
> +		dev->refresh_skip = dev->param.refresh_period;
> +
> +	if (dev->refresh_skip > 0)
> +		return oldest;
> +
> +	/*
> +	 * Refresh skip is now zero.
> +	 * We'll do a refresh this time around....
> +	 * Update the refresh skip and find the oldest block.
> +	 */
> +	dev->refresh_skip = dev->param.refresh_period;
> +	dev->refresh_count++;
> +	bi = dev->block_info;
> +	for (b = dev->internal_start_block; b <= dev->internal_end_block; b++) {
> +
> +		if (bi->block_state == YAFFS_BLOCK_STATE_FULL) {
> +
> +			if (oldest < 1 || bi->seq_number < oldest_seq) {
> +				oldest = b;
> +				oldest_seq = bi->seq_number;
> +			}
> +		}
> +		bi++;
> +	}
> +
> +	if (oldest > 0) {
> +		yaffs_trace(YAFFS_TRACE_GC,
> +			"GC refresh count %d selected block %d with seq_number %d",
> +			dev->refresh_count, oldest, oldest_seq);
> +	}
> +
> +	return oldest;
> +}
> +
> +int yaffs2_checkpt_required(struct yaffs_dev *dev)
> +{
> +	int nblocks;
> +
> +	if (!dev->param.is_yaffs2)
> +		return 0;
> +
> +	nblocks = dev->internal_end_block - dev->internal_start_block + 1;
> +
> +	return !dev->param.skip_checkpt_wr &&
> +	    !dev->read_only && (nblocks >= YAFFS_CHECKPOINT_MIN_BLOCKS);
> +}
> +
> +int yaffs_calc_checkpt_blocks_required(struct yaffs_dev *dev)
> +{
> +	int retval;
> +
> +	if (!dev->param.is_yaffs2)
> +		return 0;
> +
> +	if (!dev->checkpoint_blocks_required && yaffs2_checkpt_required(dev)) {
> +		/* Not a valid value so recalculate */
> +		int n_bytes = 0;
> +		int n_blocks;
> +		int dev_blocks =
> +		    (dev->param.end_block - dev->param.start_block + 1);
> +
> +		n_bytes += sizeof(struct yaffs_checkpt_validity);
> +		n_bytes += sizeof(struct yaffs_checkpt_dev);
> +		n_bytes += dev_blocks * sizeof(struct yaffs_block_info);
> +		n_bytes += dev_blocks * dev->chunk_bit_stride;
> +		n_bytes +=
> +		    (sizeof(struct yaffs_checkpt_obj) + sizeof(u32)) *
> +		    dev->n_obj;
> +		n_bytes += (dev->tnode_size + sizeof(u32)) * dev->n_tnodes;
> +		n_bytes += sizeof(struct yaffs_checkpt_validity);
> +		n_bytes += sizeof(u32);	/* checksum */
> +
> +		/* Round up and add 2 blocks to allow for some bad blocks,
> +		 * so add 3 */
> +
> +		n_blocks =
> +		    (n_bytes /
> +		     (dev->data_bytes_per_chunk *
> +		      dev->param.chunks_per_block)) + 3;
> +
> +		dev->checkpoint_blocks_required = n_blocks;
> +	}
> +
> +	retval = dev->checkpoint_blocks_required - dev->blocks_in_checkpt;
> +	if (retval < 0)
> +		retval = 0;
> +	return retval;
> +}
> +
> +/*--------------------- Checkpointing --------------------*/
> +
> +static int yaffs2_wr_checkpt_validity_marker(struct yaffs_dev *dev, int head)
> +{
> +	struct yaffs_checkpt_validity cp;
> +
> +	memset(&cp, 0, sizeof(cp));

Just initialise cp = {0} and drop the memset.

> +	cp.struct_type = sizeof(cp);
> +	cp.magic = YAFFS_MAGIC;
> +	cp.version = YAFFS_CHECKPOINT_VERSION;
> +	cp.head = (head) ? 1 : 0;

Don't need parens around head. Can also do:

	cp.head = !!head;

> +
> +	return (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp)) ? 1 : 0;
> +}
> +
> +static int yaffs2_rd_checkpt_validity_marker(struct yaffs_dev *dev, int head)
> +{
> +	struct yaffs_checkpt_validity cp;
> +	int ok;
> +
> +	ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
> +
> +	if (ok)
> +		ok = (cp.struct_type == sizeof(cp)) &&
> +		    (cp.magic == YAFFS_MAGIC) &&
> +		    (cp.version == YAFFS_CHECKPOINT_VERSION) &&
> +		    (cp.head == ((head) ? 1 : 0));

just cp.head == head should suffice.

> +	return ok ? 1 : 0;
> +}
> +
> +static void yaffs2_dev_to_checkpt_dev(struct yaffs_checkpt_dev *cp,
> +				      struct yaffs_dev *dev)
> +{
> +	cp->n_erased_blocks = dev->n_erased_blocks;
> +	cp->alloc_block = dev->alloc_block;
> +	cp->alloc_page = dev->alloc_page;
> +	cp->n_free_chunks = dev->n_free_chunks;
> +
> +	cp->n_deleted_files = dev->n_deleted_files;
> +	cp->n_unlinked_files = dev->n_unlinked_files;
> +	cp->n_bg_deletions = dev->n_bg_deletions;
> +	cp->seq_number = dev->seq_number;
> +
> +}
> +
> +static void yaffs_checkpt_dev_to_dev(struct yaffs_dev *dev,
> +				     struct yaffs_checkpt_dev *cp)
> +{
> +	dev->n_erased_blocks = cp->n_erased_blocks;
> +	dev->alloc_block = cp->alloc_block;
> +	dev->alloc_page = cp->alloc_page;
> +	dev->n_free_chunks = cp->n_free_chunks;
> +
> +	dev->n_deleted_files = cp->n_deleted_files;
> +	dev->n_unlinked_files = cp->n_unlinked_files;
> +	dev->n_bg_deletions = cp->n_bg_deletions;
> +	dev->seq_number = cp->seq_number;
> +}
> +
> +static int yaffs2_wr_checkpt_dev(struct yaffs_dev *dev)
> +{
> +	struct yaffs_checkpt_dev cp;
> +	u32 n_bytes;
> +	u32 n_blocks =
> +	    (dev->internal_end_block - dev->internal_start_block + 1);
> +	int ok;
> +
> +	/* Write device runtime values */
> +	yaffs2_dev_to_checkpt_dev(&cp, dev);
> +	cp.struct_type = sizeof(cp);
> +
> +	ok = (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp));
> +
> +	/* Write block info */
> +	if (ok) {
> +		n_bytes = n_blocks * sizeof(struct yaffs_block_info);
> +		ok = (yaffs2_checkpt_wr(dev, dev->block_info, n_bytes) ==
> +		      n_bytes);
> +	}
> +
> +	/* Write chunk bits */
> +	if (ok) {
> +		n_bytes = n_blocks * dev->chunk_bit_stride;
> +		ok = (yaffs2_checkpt_wr(dev, dev->chunk_bits, n_bytes) ==
> +		      n_bytes);
> +	}
> +	return ok ? 1 : 0;

Just return ok. You shouldn't need ? 1 : 0 everywhere.

> +}
> +
> +static int yaffs2_rd_checkpt_dev(struct yaffs_dev *dev)
> +{
> +	struct yaffs_checkpt_dev cp;
> +	u32 n_bytes;
> +	u32 n_blocks =
> +	    (dev->internal_end_block - dev->internal_start_block + 1);
> +	int ok;
> +
> +	ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
> +	if (!ok)
> +		return 0;
> +
> +	if (cp.struct_type != sizeof(cp))
> +		return 0;
> +
> +	yaffs_checkpt_dev_to_dev(dev, &cp);
> +
> +	n_bytes = n_blocks * sizeof(struct yaffs_block_info);
> +
> +	ok = (yaffs2_checkpt_rd(dev, dev->block_info, n_bytes) == n_bytes);
> +
> +	if (!ok)
> +		return 0;
> +	n_bytes = n_blocks * dev->chunk_bit_stride;
> +
> +	ok = (yaffs2_checkpt_rd(dev, dev->chunk_bits, n_bytes) == n_bytes);
> +
> +	return ok ? 1 : 0;
> +}
> +
> +static void yaffs2_obj_checkpt_obj(struct yaffs_checkpt_obj *cp,
> +				   struct yaffs_obj *obj)
> +{
> +	cp->obj_id = obj->obj_id;
> +	cp->parent_id = (obj->parent) ? obj->parent->obj_id : 0;
> +	cp->hdr_chunk = obj->hdr_chunk;
> +	cp->variant_type = obj->variant_type;
> +	cp->deleted = obj->deleted;
> +	cp->soft_del = obj->soft_del;
> +	cp->unlinked = obj->unlinked;
> +	cp->fake = obj->fake;
> +	cp->rename_allowed = obj->rename_allowed;
> +	cp->unlink_allowed = obj->unlink_allowed;
> +	cp->serial = obj->serial;
> +	cp->n_data_chunks = obj->n_data_chunks;
> +
> +	if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
> +		cp->size_or_equiv_obj = obj->variant.file_variant.file_size;
> +	else if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK)
> +		cp->size_or_equiv_obj = obj->variant.hardlink_variant.equiv_id;
> +}
> +
> +static int taffs2_checkpt_obj_to_obj(struct yaffs_obj *obj,
> +				     struct yaffs_checkpt_obj *cp)
> +{
> +	struct yaffs_obj *parent;
> +
> +	if (obj->variant_type != cp->variant_type) {
> +		yaffs_trace(YAFFS_TRACE_ERROR,
> +			"Checkpoint read object %d type %d chunk %d does not match existing object type %d",
> +			cp->obj_id, cp->variant_type, cp->hdr_chunk,
> +			obj->variant_type);
> +		return 0;
> +	}
> +
> +	obj->obj_id = cp->obj_id;
> +
> +	if (cp->parent_id)
> +		parent = yaffs_find_or_create_by_number(obj->my_dev,
> +						cp->parent_id,
> +						YAFFS_OBJECT_TYPE_DIRECTORY);
> +	else
> +		parent = NULL;
> +
> +	if (parent) {
> +		if (parent->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"Checkpoint read object %d parent %d type %d chunk %d Parent type, %d, not directory",
> +				cp->obj_id, cp->parent_id,
> +				cp->variant_type, cp->hdr_chunk,
> +				parent->variant_type);
> +			return 0;
> +		}
> +		yaffs_add_obj_to_dir(parent, obj);
> +	}
> +
> +	obj->hdr_chunk = cp->hdr_chunk;
> +	obj->variant_type = cp->variant_type;
> +	obj->deleted = cp->deleted;
> +	obj->soft_del = cp->soft_del;
> +	obj->unlinked = cp->unlinked;
> +	obj->fake = cp->fake;
> +	obj->rename_allowed = cp->rename_allowed;
> +	obj->unlink_allowed = cp->unlink_allowed;
> +	obj->serial = cp->serial;
> +	obj->n_data_chunks = cp->n_data_chunks;
> +
> +	if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
> +		obj->variant.file_variant.file_size = cp->size_or_equiv_obj;
> +	else if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK)
> +		obj->variant.hardlink_variant.equiv_id = cp->size_or_equiv_obj;
> +
> +	if (obj->hdr_chunk > 0)
> +		obj->lazy_loaded = 1;
> +	return 1;
> +}
> +
> +static int yaffs2_checkpt_tnode_worker(struct yaffs_obj *in,
> +				       struct yaffs_tnode *tn, u32 level,
> +				       int chunk_offset)
> +{
> +	int i;
> +	struct yaffs_dev *dev = in->my_dev;
> +	int ok = 1;
> +
> +	if (tn) {

	if (!tn)
		return 1;

Then reduce the indentation :-).

> +		if (level > 0) {
> +
> +			for (i = 0; i < YAFFS_NTNODES_INTERNAL && ok; i++) {
> +				if (tn->internal[i]) {
> +					ok = yaffs2_checkpt_tnode_worker(in,
> +						 tn->internal[i],
> +						 level - 1,
> +						 (chunk_offset <<
> +						  YAFFS_TNODES_INTERNAL_BITS)
> +						 + i);
> +				}
> +			}
> +		} else if (level == 0) {
> +			u32 base_offset =
> +			    chunk_offset << YAFFS_TNODES_LEVEL0_BITS;
> +			ok = (yaffs2_checkpt_wr
> +			      (dev, &base_offset,
> +			       sizeof(base_offset)) == sizeof(base_offset));
> +			if (ok)
> +				ok = (yaffs2_checkpt_wr
> +				      (dev, tn,
> +				       dev->tnode_size) == dev->tnode_size);
> +		}
> +	}
> +
> +	return ok;
> +}
> +
> +static int yaffs2_wr_checkpt_tnodes(struct yaffs_obj *obj)
> +{
> +	u32 end_marker = ~0;
> +	int ok = 1;
> +
> +	if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE) {

Same here, reverse the if statement and reduce the indentation.

> +		ok = yaffs2_checkpt_tnode_worker(obj,
> +						 obj->variant.file_variant.top,
> +						 obj->variant.file_variant.
> +						 top_level, 0);
> +		if (ok)
> +			ok = (yaffs2_checkpt_wr
> +			      (obj->my_dev, &end_marker,
> +			       sizeof(end_marker)) == sizeof(end_marker));
> +	}
> +
> +	return ok ? 1 : 0;
> +}
> +
> +static int yaffs2_rd_checkpt_tnodes(struct yaffs_obj *obj)
> +{
> +	u32 base_chunk;
> +	int ok = 1;
> +	struct yaffs_dev *dev = obj->my_dev;
> +	struct yaffs_file_var *file_stuct_ptr = &obj->variant.file_variant;
> +	struct yaffs_tnode *tn;
> +	int nread = 0;
> +
> +	ok = (yaffs2_checkpt_rd(dev, &base_chunk, sizeof(base_chunk)) ==
> +	      sizeof(base_chunk));
> +
> +	while (ok && (~base_chunk)) {
> +		nread++;
> +		/* Read level 0 tnode */
> +
> +		tn = yaffs_get_tnode(dev);
> +		if (tn)
> +			ok = (yaffs2_checkpt_rd(dev, tn, dev->tnode_size) ==
> +				dev->tnode_size);
> +		else
> +			ok = 0;
> +
> +		if (tn && ok)
> +			ok = yaffs_add_find_tnode_0(dev,
> +						    file_stuct_ptr,
> +						    base_chunk, tn) ? 1 : 0;
> +
> +		if (ok)
> +			ok = (yaffs2_checkpt_rd
> +			      (dev, &base_chunk,
> +			       sizeof(base_chunk)) == sizeof(base_chunk));
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"Checkpoint read tnodes %d records, last %d. ok %d",
> +		nread, base_chunk, ok);
> +
> +	return ok ? 1 : 0;
> +}
> +
> +static int yaffs2_wr_checkpt_objs(struct yaffs_dev *dev)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_checkpt_obj cp;
> +	int i;
> +	int ok = 1;
> +	struct list_head *lh;
> +
> +	/* Iterate through the objects in each hash entry,
> +	 * dumping them to the checkpointing stream.
> +	 */
> +
> +	for (i = 0; ok && i < YAFFS_NOBJECT_BUCKETS; i++) {
> +		list_for_each(lh, &dev->obj_bucket[i].list) {
> +			obj = list_entry(lh, struct yaffs_obj, hash_link);

	list_for_each_entry(lh, &dev->obj_bucket[i].list, hash_link)

> +			if (!obj->defered_free) {
> +				yaffs2_obj_checkpt_obj(&cp, obj);
> +				cp.struct_type = sizeof(cp);
> +
> +				yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +					"Checkpoint write object %d parent %d type %d chunk %d obj addr %p",
> +					cp.obj_id, cp.parent_id,
> +					cp.variant_type, cp.hdr_chunk, obj);
> +
> +				ok = (yaffs2_checkpt_wr(dev, &cp,
> +						sizeof(cp)) == sizeof(cp));
> +
> +				if (ok &&
> +					obj->variant_type ==
> +					YAFFS_OBJECT_TYPE_FILE)
> +					ok = yaffs2_wr_checkpt_tnodes(obj);
> +			}
> +		}
> +	}
> +
> +	/* Dump end of list */
> +	memset(&cp, 0xFF, sizeof(struct yaffs_checkpt_obj));
> +	cp.struct_type = sizeof(cp);
> +
> +	if (ok)
> +		ok = (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp));
> +
> +	return ok ? 1 : 0;
> +}
> +
> +static int yaffs2_rd_checkpt_objs(struct yaffs_dev *dev)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_checkpt_obj cp;
> +	int ok = 1;
> +	int done = 0;
> +	struct yaffs_obj *hard_list = NULL;
> +
> +	while (ok && !done) {
> +		ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
> +		if (cp.struct_type != sizeof(cp)) {
> +			yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +				"struct size %d instead of %d ok %d",
> +				cp.struct_type, (int)sizeof(cp), ok);
> +			ok = 0;
> +		}
> +
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"Checkpoint read object %d parent %d type %d chunk %d ",
> +			cp.obj_id, cp.parent_id, cp.variant_type,
> +			cp.hdr_chunk);
> +
> +		if (ok && cp.obj_id == ~0) {
> +			done = 1;
> +		} else if (ok) {
> +			obj =
> +			    yaffs_find_or_create_by_number(dev, cp.obj_id,
> +							   cp.variant_type);
> +			if (obj) {
> +				ok = taffs2_checkpt_obj_to_obj(obj, &cp);
> +				if (!ok)
> +					break;
> +				if (obj->variant_type ==
> +					YAFFS_OBJECT_TYPE_FILE) {
> +					ok = yaffs2_rd_checkpt_tnodes(obj);
> +				} else if (obj->variant_type ==
> +					YAFFS_OBJECT_TYPE_HARDLINK) {
> +					obj->hard_links.next =
> +					    (struct list_head *)hard_list;
> +					hard_list = obj;
> +				}
> +			} else {
> +				ok = 0;
> +			}
> +		}
> +	}
> +
> +	if (ok)
> +		yaffs_link_fixup(dev, hard_list);
> +
> +	return ok ? 1 : 0;
> +}
> +
> +static int yaffs2_wr_checkpt_sum(struct yaffs_dev *dev)
> +{
> +	u32 checkpt_sum;
> +	int ok;
> +
> +	yaffs2_get_checkpt_sum(dev, &checkpt_sum);
> +
> +	ok = (yaffs2_checkpt_wr(dev, &checkpt_sum, sizeof(checkpt_sum)) ==
> +		sizeof(checkpt_sum));
> +
> +	if (!ok)
> +		return 0;
> +
> +	return 1;

return ok; ?

> +}
> +
> +static int yaffs2_rd_checkpt_sum(struct yaffs_dev *dev)
> +{
> +	u32 checkpt_sum0;
> +	u32 checkpt_sum1;
> +	int ok;
> +
> +	yaffs2_get_checkpt_sum(dev, &checkpt_sum0);
> +
> +	ok = (yaffs2_checkpt_rd(dev, &checkpt_sum1, sizeof(checkpt_sum1)) ==
> +		sizeof(checkpt_sum1));
> +
> +	if (!ok)
> +		return 0;
> +
> +	if (checkpt_sum0 != checkpt_sum1)
> +		return 0;
> +
> +	return 1;
> +}
> +
> +static int yaffs2_wr_checkpt_data(struct yaffs_dev *dev)
> +{
> +	int ok = 1;
> +
> +	if (!yaffs2_checkpt_required(dev)) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"skipping checkpoint write");
> +		ok = 0;
> +	}
> +
> +	if (ok)
> +		ok = yaffs2_checkpt_open(dev, 1);
> +
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"write checkpoint validity");
> +		ok = yaffs2_wr_checkpt_validity_marker(dev, 1);
> +	}
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"write checkpoint device");
> +		ok = yaffs2_wr_checkpt_dev(dev);
> +	}
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"write checkpoint objects");
> +		ok = yaffs2_wr_checkpt_objs(dev);
> +	}
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"write checkpoint validity");
> +		ok = yaffs2_wr_checkpt_validity_marker(dev, 0);
> +	}
> +
> +	if (ok)
> +		ok = yaffs2_wr_checkpt_sum(dev);
> +
> +	if (!yaffs_checkpt_close(dev))
> +		ok = 0;
> +
> +	if (ok)
> +		dev->is_checkpointed = 1;
> +	else
> +		dev->is_checkpointed = 0;

dev->is_checkpointed = ok;

> +
> +	return dev->is_checkpointed;
> +}
> +
> +static int yaffs2_rd_checkpt_data(struct yaffs_dev *dev)
> +{
> +	int ok = 1;
> +
> +	if (!dev->param.is_yaffs2)
> +		ok = 0;
> +
> +	if (ok && dev->param.skip_checkpt_rd) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"skipping checkpoint read");
> +		ok = 0;
> +	}
> +
> +	if (ok)
> +		ok = yaffs2_checkpt_open(dev, 0); /* open for read */
> +
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"read checkpoint validity");
> +		ok = yaffs2_rd_checkpt_validity_marker(dev, 1);
> +	}
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"read checkpoint device");
> +		ok = yaffs2_rd_checkpt_dev(dev);
> +	}
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"read checkpoint objects");
> +		ok = yaffs2_rd_checkpt_objs(dev);
> +	}
> +	if (ok) {
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"read checkpoint validity");
> +		ok = yaffs2_rd_checkpt_validity_marker(dev, 0);
> +	}
> +
> +	if (ok) {
> +		ok = yaffs2_rd_checkpt_sum(dev);
> +		yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +			"read checkpoint checksum %d", ok);
> +	}
> +
> +	if (!yaffs_checkpt_close(dev))
> +		ok = 0;
> +
> +	if (ok)
> +		dev->is_checkpointed = 1;
> +	else
> +		dev->is_checkpointed = 0;

dev->is_checkpointed = ok;

> +
> +	return ok ? 1 : 0;
> +}
> +
> +void yaffs2_checkpt_invalidate(struct yaffs_dev *dev)
> +{
> +	if (dev->is_checkpointed || dev->blocks_in_checkpt > 0) {
> +		dev->is_checkpointed = 0;
> +		yaffs2_checkpt_invalidate_stream(dev);
> +	}
> +	if (dev->param.sb_dirty_fn)
> +		dev->param.sb_dirty_fn(dev);
> +}
> +
> +int yaffs_checkpoint_save(struct yaffs_dev *dev)
> +{
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"save entry: is_checkpointed %d",
> +		dev->is_checkpointed);
> +
> +	yaffs_verify_objects(dev);
> +	yaffs_verify_blocks(dev);
> +	yaffs_verify_free_chunks(dev);
> +
> +	if (!dev->is_checkpointed) {
> +		yaffs2_checkpt_invalidate(dev);
> +		yaffs2_wr_checkpt_data(dev);
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT | YAFFS_TRACE_MOUNT,
> +		"save exit: is_checkpointed %d",
> +		dev->is_checkpointed);
> +
> +	return dev->is_checkpointed;
> +}
> +
> +int yaffs2_checkpt_restore(struct yaffs_dev *dev)
> +{
> +	int retval;
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"restore entry: is_checkpointed %d",
> +		dev->is_checkpointed);
> +
> +	retval = yaffs2_rd_checkpt_data(dev);
> +
> +	if (dev->is_checkpointed) {
> +		yaffs_verify_objects(dev);
> +		yaffs_verify_blocks(dev);
> +		yaffs_verify_free_chunks(dev);
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_CHECKPOINT,
> +		"restore exit: is_checkpointed %d",
> +		dev->is_checkpointed);
> +
> +	return retval;
> +}
> +
> +int yaffs2_handle_hole(struct yaffs_obj *obj, loff_t new_size)
> +{
> +	/* if new_size > old_file_size.
> +	 * We're going to be writing a hole.
> +	 * If the hole is small then write zeros otherwise write a start
> +	 * of hole marker.
> +	 */
> +	loff_t old_file_size;
> +	int increase;
> +	int small_hole;
> +	int result = YAFFS_OK;
> +	struct yaffs_dev *dev = NULL;
> +	u8 *local_buffer = NULL;
> +	int small_increase_ok = 0;
> +
> +	if (!obj)
> +		return YAFFS_FAIL;
> +
> +	if (obj->variant_type != YAFFS_OBJECT_TYPE_FILE)
> +		return YAFFS_FAIL;
> +
> +	dev = obj->my_dev;
> +
> +	/* Bail out if not yaffs2 mode */
> +	if (!dev->param.is_yaffs2)
> +		return YAFFS_OK;
> +
> +	old_file_size = obj->variant.file_variant.file_size;
> +
> +	if (new_size <= old_file_size)
> +		return YAFFS_OK;
> +
> +	increase = new_size - old_file_size;
> +
> +	if (increase < YAFFS_SMALL_HOLE_THRESHOLD * dev->data_bytes_per_chunk &&
> +	    yaffs_check_alloc_available(dev, YAFFS_SMALL_HOLE_THRESHOLD + 1))
> +		small_hole = 1;
> +	else
> +		small_hole = 0;
> +
> +	if (small_hole)
> +		local_buffer = yaffs_get_temp_buffer(dev, __LINE__);

small_hole only gets used for this test? Remove the small_hole variable
and make the if happen directly.

> +
> +	if (local_buffer) {
> +		/* fill hole with zero bytes */
> +		int pos = old_file_size;
> +		int this_write;
> +		int written;
> +		memset(local_buffer, 0, dev->data_bytes_per_chunk);
> +		small_increase_ok = 1;
> +
> +		while (increase > 0 && small_increase_ok) {
> +			this_write = increase;
> +			if (this_write > dev->data_bytes_per_chunk)
> +				this_write = dev->data_bytes_per_chunk;
> +			written =
> +			    yaffs_do_file_wr(obj, local_buffer, pos, this_write,
> +					     0);
> +			if (written == this_write) {
> +				pos += this_write;
> +				increase -= this_write;
> +			} else {
> +				small_increase_ok = 0;
> +			}
> +		}
> +
> +		yaffs_release_temp_buffer(dev, local_buffer, __LINE__);
> +
> +		/* If out of space then reverse any chunks we've added */
> +		if (!small_increase_ok)
> +			yaffs_resize_file_down(obj, old_file_size);
> +	}
> +
> +	if (!small_increase_ok &&
> +	    obj->parent &&
> +	    obj->parent->obj_id != YAFFS_OBJECTID_UNLINKED &&
> +	    obj->parent->obj_id != YAFFS_OBJECTID_DELETED) {
> +		/* Write a hole start header with the old file size */
> +		yaffs_update_oh(obj, NULL, 0, 1, 0, NULL);
> +	}
> +
> +	return result;
> +}
> +
> +struct yaffs_block_index {
> +	int seq;
> +	int block;
> +};
> +
> +static int yaffs2_ybicmp(const void *a, const void *b)
> +{
> +	int aseq = ((struct yaffs_block_index *)a)->seq;
> +	int bseq = ((struct yaffs_block_index *)b)->seq;
> +	int ablock = ((struct yaffs_block_index *)a)->block;
> +	int bblock = ((struct yaffs_block_index *)b)->block;
> +
> +	if (aseq == bseq)
> +		return ablock - bblock;
> +	else
> +		return aseq - bseq;
> +}
> +
> +static inline int yaffs2_scan_chunk(struct yaffs_dev *dev,
> +		struct yaffs_block_info *bi,
> +		int blk, int chunk_in_block,
> +		int *found_chunks,
> +		u8 *chunk_data,
> +		struct yaffs_obj **hard_list)
> +{
> +	struct yaffs_obj_hdr *oh;
> +	struct yaffs_obj *in;
> +	struct yaffs_obj *parent;
> +	int equiv_id;
> +	int file_size;
> +	int is_shrink;
> +	int is_unlinked;
> +	struct yaffs_ext_tags tags;
> +	int result;
> +	int alloc_failed = 0;
> +	int chunk = blk * dev->param.chunks_per_block + chunk_in_block;
> +	struct yaffs_file_var *file_var;
> +	struct yaffs_hardlink_var *hl_var;
> +	struct yaffs_symlink_var *sl_var;
> +
> +	result = yaffs_rd_chunk_tags_nand(dev, chunk, NULL, &tags);
> +
> +	/* Let's have a good look at this chunk... */
> +
> +	if (!tags.chunk_used) {
> +		/* An unassigned chunk in the block.
> +		 * If there are used chunks after this one, then
> +		 * it is a chunk that was skipped due to failing
> +		 * the erased check. Just skip it so that it can
> +		 * be deleted.
> +		 * But, more typically, We get here when this is
> +		 * an unallocated chunk and his means that
> +		 * either the block is empty or this is the one
> +		 * being allocated from
> +		 */
> +
> +		if (*found_chunks) {
> +			/* This is a chunk that was skipped due
> +			 * to failing the erased check */
> +		} else if (chunk_in_block == 0) {
> +			/* We're looking at the first chunk in
> +			 * the block so the block is unused */
> +			bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
> +			dev->n_erased_blocks++;
> +		} else {
> +			if (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCANNING
> +			   || bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING) {
> +				if (dev->seq_number == bi->seq_number) {
> +					/* Allocating from this block*/
> +					yaffs_trace(YAFFS_TRACE_SCAN,
> +					    " Allocating from %d %d",
> +					    blk, chunk_in_block);
> +
> +					bi->block_state =
> +						YAFFS_BLOCK_STATE_ALLOCATING;
> +					dev->alloc_block = blk;
> +					dev->alloc_page = chunk_in_block;
> +					dev->alloc_block_finder = blk;
> +				} else {
> +					/* This is a partially written block
> +					 * that is not the current
> +					 * allocation block.
> +					 */
> +					yaffs_trace(YAFFS_TRACE_SCAN,
> +						"Partially written block %d detected. gc will fix this.",
> +						blk);
> +				}
> +			}
> +		}
> +
> +		dev->n_free_chunks++;
> +
> +	} else if (tags.ecc_result ==
> +		YAFFS_ECC_RESULT_UNFIXED) {
> +		yaffs_trace(YAFFS_TRACE_SCAN,
> +			" Unfixed ECC in chunk(%d:%d), chunk ignored",
> +			blk, chunk_in_block);
> +			dev->n_free_chunks++;
> +	} else if (tags.obj_id > YAFFS_MAX_OBJECT_ID ||
> +		   tags.chunk_id > YAFFS_MAX_CHUNK_ID ||
> +		   (tags.chunk_id > 0 &&
> +		     tags.n_bytes > dev->data_bytes_per_chunk) ||
> +		   tags.seq_number != bi->seq_number) {
> +		yaffs_trace(YAFFS_TRACE_SCAN,
> +			"Chunk (%d:%d) with bad tags:obj = %d, chunk_id = %d, n_bytes = %d, ignored",
> +			blk, chunk_in_block, tags.obj_id,
> +			tags.chunk_id, tags.n_bytes);
> +		dev->n_free_chunks++;
> +	} else if (tags.chunk_id > 0) {
> +		/* chunk_id > 0 so it is a data chunk... */
> +		unsigned int endpos;
> +		u32 chunk_base = (tags.chunk_id - 1) *
> +					dev->data_bytes_per_chunk;
> +
> +		*found_chunks = 1;
> +
> +		yaffs_set_chunk_bit(dev, blk, chunk_in_block);
> +		bi->pages_in_use++;
> +
> +		in = yaffs_find_or_create_by_number(dev,
> +					tags.obj_id,
> +					YAFFS_OBJECT_TYPE_FILE);
> +		if (!in)
> +			/* Out of memory */
> +			alloc_failed = 1;

Bail: goto alloc_failed;

> +
> +		if (in &&
> +		    in->variant_type == YAFFS_OBJECT_TYPE_FILE &&
> +		    chunk_base < in->variant.file_variant.shrink_size) {
> +			/* This has not been invalidated by
> +			 * a resize */
> +			if (!yaffs_put_chunk_in_file(in, tags.chunk_id,
> +								chunk, -1))
> +				alloc_failed = 1;
> +
> +			/* File size is calculated by looking at
> +			 * the data chunks if we have not
> +			 * seen an object header yet.
> +			 * Stop this practice once we find an
> +			 * object header.
> +			 */
> +			endpos = chunk_base + tags.n_bytes;
> +
> +			if (!in->valid &&
> +			    in->variant.file_variant.scanned_size < endpos) {
> +				in->variant.file_variant.
> +				    scanned_size = endpos;
> +				in->variant.file_variant.
> +				    file_size = endpos;
> +			}
> +		} else if (in) {
> +			/* This chunk has been invalidated by a
> +			 * resize, or a past file deletion
> +			 * so delete the chunk*/
> +			yaffs_chunk_del(dev, chunk, 1, __LINE__);
> +		}
> +	} else {
> +		/* chunk_id == 0, so it is an ObjectHeader.
> +		 * Thus, we read in the object header and make
> +		 * the object
> +		 */
> +		*found_chunks = 1;
> +
> +		yaffs_set_chunk_bit(dev, blk, chunk_in_block);
> +		bi->pages_in_use++;
> +
> +		oh = NULL;
> +		in = NULL;
> +
> +		if (tags.extra_available) {
> +			in = yaffs_find_or_create_by_number(dev,
> +					tags.obj_id,
> +					tags.extra_obj_type);
> +			if (!in)
> +				alloc_failed = 1;
> +		}
> +
> +		if (!in ||
> +		    (!in->valid && dev->param.disable_lazy_load)
> +		    || tags.extra_shadows ||
> +		    (!in->valid && (tags.obj_id ==
> +				YAFFS_OBJECTID_ROOT
> +				|| tags.obj_id ==
> +				YAFFS_OBJECTID_LOSTNFOUND))) {

My brain hurts :-).

> +
> +			/* If we don't have  valid info then we
> +			 * need to read the chunk
> +			 * TODO In future we can probably defer
> +			 * reading the chunk and living with
> +			 * invalid data until needed.
> +			 */
> +
> +			result = yaffs_rd_chunk_tags_nand(dev,
> +						  chunk,
> +						  chunk_data,
> +						  NULL);
> +
> +			oh = (struct yaffs_obj_hdr *)chunk_data;
> +
> +			if (dev->param.inband_tags) {
> +				/* Fix up the header if they got
> +				 * corrupted by inband tags */
> +				oh->shadows_obj =
> +				    oh->inband_shadowed_obj_id;
> +				oh->is_shrink =
> +				    oh->inband_is_shrink;
> +			}
> +
> +			if (!in) {
> +				in = yaffs_find_or_create_by_number(dev,
> +							tags.obj_id, oh->type);
> +				if (!in)
> +					alloc_failed = 1;
> +			}
> +		}
> +
> +		if (!in) {
> +			/* TODO Hoosterman we have a problem! */
> +			yaffs_trace(YAFFS_TRACE_ERROR,
> +				"yaffs tragedy: Could not make object for object  %d at chunk %d during scan",
> +				tags.obj_id, chunk);
> +			return YAFFS_FAIL;
> +		}
> +
> +		if (in->valid) {
> +			/* We have already filled this one.
> +			 * We have a duplicate that will be
> +			 * discarded, but we first have to suck
> +			 * out resize info if it is a file.
> +			 */
> +			if ((in->variant_type == YAFFS_OBJECT_TYPE_FILE) &&
> +				((oh && oh->type == YAFFS_OBJECT_TYPE_FILE) ||
> +				 (tags.extra_available &&
> +				  tags.extra_obj_type == YAFFS_OBJECT_TYPE_FILE)
> +				)) {
> +				u32 this_size = (oh) ?
> +					oh->file_size :
> +					tags.extra_length;
> +				u32 parent_obj_id = (oh) ?
> +					oh->parent_obj_id :
> +					tags.extra_parent_id;
> +
> +				is_shrink = (oh) ?
> +					oh->is_shrink :
> +					tags.extra_is_shrink;
> +
> +				/* If it is deleted (unlinked
> +				 * at start also means deleted)
> +				 * we treat the file size as
> +				 * being zeroed at this point.
> +				 */
> +				if (parent_obj_id == YAFFS_OBJECTID_DELETED ||
> +				    parent_obj_id == YAFFS_OBJECTID_UNLINKED) {
> +					this_size = 0;
> +					is_shrink = 1;
> +				}
> +
> +				if (is_shrink &&
> +				    in->variant.file_variant.shrink_size >
> +				    this_size)
> +					in->variant.file_variant.shrink_size =
> +					this_size;
> +
> +				if (is_shrink)
> +					bi->has_shrink_hdr = 1;
> +			}
> +			/* Use existing - destroy this one. */
> +			yaffs_chunk_del(dev, chunk, 1, __LINE__);
> +		}
> +
> +		if (!in->valid && in->variant_type !=
> +		    (oh ? oh->type : tags.extra_obj_type))
> +			yaffs_trace(YAFFS_TRACE_ERROR,
> +				"yaffs tragedy: Bad object type, %d != %d, for object %d at chunk %d during scan",
> +				oh ? oh->type : tags.extra_obj_type,
> +				in->variant_type, tags.obj_id,
> +				chunk);
> +
> +		if (!in->valid &&
> +		    (tags.obj_id == YAFFS_OBJECTID_ROOT ||
> +		     tags.obj_id == YAFFS_OBJECTID_LOSTNFOUND)) {
> +			/* We only load some info, don't fiddle
> +			 * with directory structure */
> +			in->valid = 1;
> +
> +			if (oh) {
> +				in->yst_mode = oh->yst_mode;
> +				yaffs_load_attribs(in, oh);
> +				in->lazy_loaded = 0;
> +			} else {
> +				in->lazy_loaded = 1;
> +			}
> +			in->hdr_chunk = chunk;
> +
> +		} else if (!in->valid) {
> +			/* we need to load this info */
> +			in->valid = 1;
> +			in->hdr_chunk = chunk;
> +			if (oh) {
> +				in->variant_type = oh->type;
> +				in->yst_mode = oh->yst_mode;
> +				yaffs_load_attribs(in, oh);
> +
> +				if (oh->shadows_obj > 0)
> +					yaffs_handle_shadowed_obj(dev,
> +					     oh->shadows_obj, 1);
> +
> +				yaffs_set_obj_name_from_oh(in, oh);
> +				parent = yaffs_find_or_create_by_number(dev,
> +						oh->parent_obj_id,
> +						YAFFS_OBJECT_TYPE_DIRECTORY);
> +				file_size = oh->file_size;
> +				is_shrink = oh->is_shrink;
> +				equiv_id = oh->equiv_id;
> +			} else {
> +				in->variant_type = tags.extra_obj_type;
> +				parent = yaffs_find_or_create_by_number(dev,
> +						tags.extra_parent_id,
> +						YAFFS_OBJECT_TYPE_DIRECTORY);
> +				file_size = tags.extra_length;
> +				is_shrink = tags.extra_is_shrink;
> +				equiv_id = tags.extra_equiv_id;
> +				in->lazy_loaded = 1;
> +			}
> +			in->dirty = 0;
> +
> +			if (!parent)
> +				alloc_failed = 1;
> +
> +			/* directory stuff...
> +			 * hook up to parent
> +			 */
> +
> +			if (parent &&
> +			    parent->variant_type == YAFFS_OBJECT_TYPE_UNKNOWN) {
> +				/* Set up as a directory */
> +				parent->variant_type =
> +					YAFFS_OBJECT_TYPE_DIRECTORY;
> +				INIT_LIST_HEAD(&parent->
> +						variant.dir_variant.children);
> +			} else if (!parent ||
> +				   parent->variant_type !=
> +					YAFFS_OBJECT_TYPE_DIRECTORY) {
> +				/* Hoosterman, another problem....
> +				 * Trying to use a non-directory as a directory
> +				 */
> +
> +				yaffs_trace(YAFFS_TRACE_ERROR,
> +					"yaffs tragedy: attempting to use non-directory as a directory in scan. Put in lost+found."
> +					);
> +				parent = dev->lost_n_found;
> +			}
> +			yaffs_add_obj_to_dir(parent, in);
> +
> +			is_unlinked = (parent == dev->del_dir) ||
> +					(parent == dev->unlinked_dir);
> +
> +			if (is_shrink)
> +				/* Mark the block */
> +				bi->has_shrink_hdr = 1;
> +
> +			/* Note re hardlinks.
> +			 * Since we might scan a hardlink before its equivalent
> +			 * object is scanned we put them all in a list.
> +			 * After scanning is complete, we should have all the
> +			 * objects, so we run through this list and fix up all
> +			 * the chains.
> +			 */
> +
> +			switch (in->variant_type) {
> +			case YAFFS_OBJECT_TYPE_UNKNOWN:
> +				/* Todo got a problem */
> +				break;
> +			case YAFFS_OBJECT_TYPE_FILE:
> +				file_var = &in->variant.file_variant;
> +				if (file_var->scanned_size < file_size) {
> +					/* This covers the case where the file
> +					 * size is greater than the data held.
> +					 * This will happen if the file is
> +					 * resized to be larger than its
> +					 * current data extents.
> +					 */
> +					file_var->file_size = file_size;
> +					file_var->scanned_size = file_size;
> +				}
> +
> +				if (file_var->shrink_size > file_size)
> +					file_var->shrink_size = file_size;
> +
> +				break;
> +			case YAFFS_OBJECT_TYPE_HARDLINK:
> +				hl_var = &in->variant.hardlink_variant;
> +				if (!is_unlinked) {
> +					hl_var->equiv_id = equiv_id;
> +					in->hard_links.next =
> +					    (struct list_head *) *hard_list;

List trickery?

> +					*hard_list = in;
> +				}
> +				break;
> +			case YAFFS_OBJECT_TYPE_DIRECTORY:
> +				/* Do nothing */
> +				break;
> +			case YAFFS_OBJECT_TYPE_SPECIAL:
> +				/* Do nothing */
> +				break;
> +			case YAFFS_OBJECT_TYPE_SYMLINK:
> +				sl_var = &in->variant.symlink_variant;
> +				if (oh) {
> +					sl_var->alias =
> +					    yaffs_clone_str(oh->alias);
> +					if (!sl_var->alias)
> +						alloc_failed = 1;
> +				}
> +				break;
> +			}
> +		}
> +	}
> +	return alloc_failed ? YAFFS_FAIL : YAFFS_OK;
> +}
> +
> +int yaffs2_scan_backwards(struct yaffs_dev *dev)
> +{
> +	int blk;
> +	int block_iter;
> +	int start_iter;
> +	int end_iter;
> +	int n_to_scan = 0;
> +	enum yaffs_block_state state;
> +	int c;
> +	int deleted;
> +	struct yaffs_obj *hard_list = NULL;
> +	struct yaffs_block_info *bi;
> +	u32 seq_number;
> +	int n_blocks = dev->internal_end_block - dev->internal_start_block + 1;
> +	u8 *chunk_data;
> +	int found_chunks;
> +	int alloc_failed = 0;
> +	struct yaffs_block_index *block_index = NULL;
> +	int alt_block_index = 0;
> +
> +	yaffs_trace(YAFFS_TRACE_SCAN,
> +		"yaffs2_scan_backwards starts  intstartblk %d intendblk %d...",
> +		dev->internal_start_block, dev->internal_end_block);
> +
> +	dev->seq_number = YAFFS_LOWEST_SEQUENCE_NUMBER;
> +
> +	block_index = kmalloc(n_blocks * sizeof(struct yaffs_block_index),
> +			GFP_NOFS);
> +
> +	if (!block_index) {
> +		block_index =
> +		    vmalloc(n_blocks * sizeof(struct yaffs_block_index));
> +		alt_block_index = 1;

How big is this alloc? Does it make more sense to just always use
vmalloc and simplify the code?

> +	}
> +
> +	if (!block_index) {
> +		yaffs_trace(YAFFS_TRACE_SCAN,
> +			"yaffs2_scan_backwards() could not allocate block index!"
> +			);
> +		return YAFFS_FAIL;
> +	}
> +
> +	dev->blocks_in_checkpt = 0;
> +
> +	chunk_data = yaffs_get_temp_buffer(dev, __LINE__);
> +
> +	/* Scan all the blocks to determine their state */
> +	bi = dev->block_info;
> +	for (blk = dev->internal_start_block; blk <= dev->internal_end_block;
> +	     blk++) {
> +		yaffs_clear_chunk_bits(dev, blk);
> +		bi->pages_in_use = 0;
> +		bi->soft_del_pages = 0;
> +
> +		yaffs_query_init_block_state(dev, blk, &state, &seq_number);
> +
> +		bi->block_state = state;
> +		bi->seq_number = seq_number;
> +
> +		if (bi->seq_number == YAFFS_SEQUENCE_CHECKPOINT_DATA)
> +			bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
> +		if (bi->seq_number == YAFFS_SEQUENCE_BAD_BLOCK)
> +			bi->block_state = YAFFS_BLOCK_STATE_DEAD;
> +
> +		yaffs_trace(YAFFS_TRACE_SCAN_DEBUG,
> +			"Block scanning block %d state %d seq %d",
> +			blk, bi->block_state, seq_number);
> +
> +		if (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT) {
> +			dev->blocks_in_checkpt++;
> +
> +		} else if (bi->block_state == YAFFS_BLOCK_STATE_DEAD) {
> +			yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
> +				"block %d is bad", blk);
> +		} else if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
> +			yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "Block empty ");
> +			dev->n_erased_blocks++;
> +			dev->n_free_chunks += dev->param.chunks_per_block;
> +		} else if (bi->block_state ==
> +				YAFFS_BLOCK_STATE_NEEDS_SCANNING) {
> +			/* Determine the highest sequence number */
> +			if (seq_number >= YAFFS_LOWEST_SEQUENCE_NUMBER &&
> +			    seq_number < YAFFS_HIGHEST_SEQUENCE_NUMBER) {
> +				block_index[n_to_scan].seq = seq_number;
> +				block_index[n_to_scan].block = blk;
> +				n_to_scan++;
> +				if (seq_number >= dev->seq_number)
> +					dev->seq_number = seq_number;
> +			} else {
> +				/* TODO: Nasty sequence number! */
> +				yaffs_trace(YAFFS_TRACE_SCAN,
> +					"Block scanning block %d has bad sequence number %d",
> +					blk, seq_number);
> +			}
> +		}
> +		bi++;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_SCAN, "%d blocks to be sorted...", n_to_scan);
> +
> +	cond_resched();
> +
> +	/* Sort the blocks by sequence number */
> +	sort(block_index, n_to_scan, sizeof(struct yaffs_block_index),
> +		   yaffs2_ybicmp, NULL);
> +
> +	cond_resched();
> +
> +	yaffs_trace(YAFFS_TRACE_SCAN, "...done");
> +
> +	/* Now scan the blocks looking at the data. */
> +	start_iter = 0;
> +	end_iter = n_to_scan - 1;
> +	yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "%d blocks to scan", n_to_scan);
> +
> +	/* For each block.... backwards */
> +	for (block_iter = end_iter; !alloc_failed && block_iter >= start_iter;
> +	     block_iter--) {
> +		/* Cooperative multitasking! This loop can run for so
> +		   long that watchdog timers expire. */
> +		cond_resched();

Can parts of it be moved to a tasklet, kernel thread, etc?

> +
> +		/* get the block to scan in the correct order */
> +		blk = block_index[block_iter].block;
> +		bi = yaffs_get_block_info(dev, blk);
> +		deleted = 0;
> +
> +		/* For each chunk in each block that needs scanning.... */
> +		found_chunks = 0;
> +		for (c = dev->param.chunks_per_block - 1;
> +		     !alloc_failed && c >= 0 &&
> +		     (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCANNING ||
> +		      bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING); c--) {
> +			/* Scan backwards...
> +			 * Read the tags and decide what to do
> +			 */
> +			if (yaffs2_scan_chunk(dev, bi, blk, c,
> +					&found_chunks, chunk_data,
> +					&hard_list) ==
> +				YAFFS_FAIL)
> +				alloc_failed = 1;
> +		}
> +
> +		if (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCANNING) {
> +			/* If we got this far while scanning, then the block
> +			 * is fully allocated. */
> +			bi->block_state = YAFFS_BLOCK_STATE_FULL;
> +		}
> +
> +		/* Now let's see if it was dirty */
> +		if (bi->pages_in_use == 0 &&
> +		    !bi->has_shrink_hdr &&
> +		    bi->block_state == YAFFS_BLOCK_STATE_FULL) {
> +			yaffs_block_became_dirty(dev, blk);
> +		}
> +	}
> +
> +	yaffs_skip_rest_of_block(dev);
> +
> +	if (alt_block_index)
> +		vfree(block_index);
> +	else
> +		kfree(block_index);
> +
> +	/* Ok, we've done all the scanning.
> +	 * Fix up the hard link chains.
> +	 * We have scanned all the objects, now it's time to add these
> +	 * hardlinks.
> +	 */
> +	yaffs_link_fixup(dev, hard_list);
> +
> +	yaffs_release_temp_buffer(dev, chunk_data, __LINE__);
> +
> +	if (alloc_failed)
> +		return YAFFS_FAIL;
> +
> +	yaffs_trace(YAFFS_TRACE_SCAN, "yaffs2_scan_backwards ends");
> +
> +	return YAFFS_OK;
> +}
> diff --git a/fs/yaffs2/yaffs_yaffs2.h b/fs/yaffs2/yaffs_yaffs2.h
> new file mode 100644
> index 0000000..e1a9287
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_yaffs2.h
> @@ -0,0 +1,39 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_YAFFS2_H__
> +#define __YAFFS_YAFFS2_H__
> +
> +#include "yaffs_guts.h"
> +
> +void yaffs_calc_oldest_dirty_seq(struct yaffs_dev *dev);
> +void yaffs2_find_oldest_dirty_seq(struct yaffs_dev *dev);
> +void yaffs2_clear_oldest_dirty_seq(struct yaffs_dev *dev,
> +				   struct yaffs_block_info *bi);
> +void yaffs2_update_oldest_dirty_seq(struct yaffs_dev *dev, unsigned block_no,
> +				    struct yaffs_block_info *bi);
> +int yaffs_block_ok_for_gc(struct yaffs_dev *dev, struct yaffs_block_info *bi);
> +u32 yaffs2_find_refresh_block(struct yaffs_dev *dev);
> +int yaffs2_checkpt_required(struct yaffs_dev *dev);
> +int yaffs_calc_checkpt_blocks_required(struct yaffs_dev *dev);
> +
> +void yaffs2_checkpt_invalidate(struct yaffs_dev *dev);
> +int yaffs2_checkpt_save(struct yaffs_dev *dev);
> +int yaffs2_checkpt_restore(struct yaffs_dev *dev);
> +
> +int yaffs2_handle_hole(struct yaffs_obj *obj, loff_t new_size);
> +int yaffs2_scan_backwards(struct yaffs_dev *dev);
> +
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 08/10] Add yaffs2 file system: Core guts code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_guts.c | 5028 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yaffs_guts.h |  938 +++++++++
 2 files changed, 5966 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_guts.c
 create mode 100644 fs/yaffs2/yaffs_guts.h

diff --git a/fs/yaffs2/yaffs_guts.c b/fs/yaffs2/yaffs_guts.c
new file mode 100644
index 0000000..a579eee
--- /dev/null
+++ b/fs/yaffs2/yaffs_guts.c
@@ -0,0 +1,5028 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "yportenv.h"
+#include "yaffs_trace.h"
+
+#include "yaffs_guts.h"
+#include "yaffs_tagsvalidity.h"
+#include "yaffs_getblockinfo.h"
+#include "yaffs_tagscompat.h"
+#include "yaffs_nand.h"
+#include "yaffs_yaffs1.h"
+#include "yaffs_yaffs2.h"
+#include "yaffs_bitmap.h"
+#include "yaffs_verify.h"
+#include "yaffs_nand.h"
+#include "yaffs_packedtags2.h"
+#include "yaffs_nameval.h"
+#include "yaffs_allocator.h"
+#include "yaffs_attribs.h"
+
+/* Note YAFFS_GC_GOOD_ENOUGH must be <= YAFFS_GC_PASSIVE_THRESHOLD */
+#define YAFFS_GC_GOOD_ENOUGH 2
+#define YAFFS_GC_PASSIVE_THRESHOLD 4
+
+#include "yaffs_ecc.h"
+
+/* Forward declarations */
+
+static int yaffs_wr_data_obj(struct yaffs_obj *in, int inode_chunk,
+			     const u8 *buffer, int n_bytes, int use_reserve);
+
+
+
+/* Function to calculate chunk and offset */
+
+static void yaffs_addr_to_chunk(struct yaffs_dev *dev, loff_t addr,
+				int *chunk_out, u32 *offset_out)
+{
+	int chunk;
+	u32 offset;
+
+	chunk = (u32) (addr >> dev->chunk_shift);
+
+	if (dev->chunk_div == 1) {
+		/* easy power of 2 case */
+		offset = (u32) (addr & dev->chunk_mask);
+	} else {
+		/* Non power-of-2 case */
+
+		loff_t chunk_base;
+
+		chunk /= dev->chunk_div;
+
+		chunk_base = ((loff_t) chunk) * dev->data_bytes_per_chunk;
+		offset = (u32) (addr - chunk_base);
+	}
+
+	*chunk_out = chunk;
+	*offset_out = offset;
+}
+
+/* Function to return the number of shifts for a power of 2 greater than or
+ * equal to the given number
+ * Note we don't try to cater for all possible numbers and this does not have to
+ * be hellishly efficient.
+ */
+
+static u32 calc_shifts_ceiling(u32 x)
+{
+	int extra_bits;
+	int shifts;
+
+	shifts = extra_bits = 0;
+
+	while (x > 1) {
+		if (x & 1)
+			extra_bits++;
+		x >>= 1;
+		shifts++;
+	}
+
+	if (extra_bits)
+		shifts++;
+
+	return shifts;
+}
+
+/* Function to return the number of shifts to get a 1 in bit 0
+ */
+
+static u32 calc_shifts(u32 x)
+{
+	u32 shifts;
+
+	shifts = 0;
+
+	if (!x)
+		return 0;
+
+	while (!(x & 1)) {
+		x >>= 1;
+		shifts++;
+	}
+
+	return shifts;
+}
+
+/*
+ * Temporary buffer manipulations.
+ */
+
+static int yaffs_init_tmp_buffers(struct yaffs_dev *dev)
+{
+	int i;
+	u8 *buf = (u8 *) 1;
+
+	memset(dev->temp_buffer, 0, sizeof(dev->temp_buffer));
+
+	for (i = 0; buf && i < YAFFS_N_TEMP_BUFFERS; i++) {
+		dev->temp_buffer[i].line = 0;	/* not in use */
+		dev->temp_buffer[i].buffer = buf =
+		    kmalloc(dev->param.total_bytes_per_chunk, GFP_NOFS);
+	}
+
+	return buf ? YAFFS_OK : YAFFS_FAIL;
+}
+
+u8 *yaffs_get_temp_buffer(struct yaffs_dev * dev, int line_no)
+{
+	int i;
+	int j;
+
+	dev->temp_in_use++;
+	if (dev->temp_in_use > dev->max_temp)
+		dev->max_temp = dev->temp_in_use;
+
+	for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++) {
+		if (dev->temp_buffer[i].line == 0) {
+			dev->temp_buffer[i].line = line_no;
+			if ((i + 1) > dev->max_temp) {
+				dev->max_temp = i + 1;
+				for (j = 0; j <= i; j++)
+					dev->temp_buffer[j].max_line =
+					    dev->temp_buffer[j].line;
+			}
+
+			return dev->temp_buffer[i].buffer;
+		}
+	}
+
+	yaffs_trace(YAFFS_TRACE_BUFFERS,
+		"Out of temp buffers at line %d, other held by lines:",
+		line_no);
+	for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++)
+		yaffs_trace(YAFFS_TRACE_BUFFERS,
+			" %d", dev->temp_buffer[i].line);
+
+	/*
+	 * If we got here then we have to allocate an unmanaged one
+	 * This is not good.
+	 */
+
+	dev->unmanaged_buffer_allocs++;
+	return kmalloc(dev->data_bytes_per_chunk, GFP_NOFS);
+
+}
+
+void yaffs_release_temp_buffer(struct yaffs_dev *dev, u8 *buffer, int line_no)
+{
+	int i;
+
+	dev->temp_in_use--;
+
+	for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++) {
+		if (dev->temp_buffer[i].buffer == buffer) {
+			dev->temp_buffer[i].line = 0;
+			return;
+		}
+	}
+
+	if (buffer) {
+		/* assume it is an unmanaged one. */
+		yaffs_trace(YAFFS_TRACE_BUFFERS,
+		  "Releasing unmanaged temp buffer in line %d",
+		   line_no);
+		kfree(buffer);
+		dev->unmanaged_buffer_deallocs++;
+	}
+
+}
+
+/*
+ * Determine if we have a managed buffer.
+ */
+int yaffs_is_managed_tmp_buffer(struct yaffs_dev *dev, const u8 *buffer)
+{
+	int i;
+
+	for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++) {
+		if (dev->temp_buffer[i].buffer == buffer)
+			return 1;
+	}
+
+	for (i = 0; i < dev->param.n_caches; i++) {
+		if (dev->cache[i].data == buffer)
+			return 1;
+	}
+
+	if (buffer == dev->checkpt_buffer)
+		return 1;
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+	  "yaffs: unmaged buffer detected.");
+	return 0;
+}
+
+/*
+ * Functions for robustisizing TODO
+ *
+ */
+
+static void yaffs_handle_chunk_wr_ok(struct yaffs_dev *dev, int nand_chunk,
+				     const u8 *data,
+				     const struct yaffs_ext_tags *tags)
+{
+	dev = dev;
+	nand_chunk = nand_chunk;
+	data = data;
+	tags = tags;
+}
+
+static void yaffs_handle_chunk_update(struct yaffs_dev *dev, int nand_chunk,
+				      const struct yaffs_ext_tags *tags)
+{
+	dev = dev;
+	nand_chunk = nand_chunk;
+	tags = tags;
+}
+
+void yaffs_handle_chunk_error(struct yaffs_dev *dev,
+			      struct yaffs_block_info *bi)
+{
+	if (!bi->gc_prioritise) {
+		bi->gc_prioritise = 1;
+		dev->has_pending_prioritised_gc = 1;
+		bi->chunk_error_strikes++;
+
+		if (bi->chunk_error_strikes > 3) {
+			bi->needs_retiring = 1;	/* Too many stikes, so retire */
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"yaffs: Block struck out");
+
+		}
+	}
+}
+
+static void yaffs_handle_chunk_wr_error(struct yaffs_dev *dev, int nand_chunk,
+					int erased_ok)
+{
+	int flash_block = nand_chunk / dev->param.chunks_per_block;
+	struct yaffs_block_info *bi = yaffs_get_block_info(dev, flash_block);
+
+	yaffs_handle_chunk_error(dev, bi);
+
+	if (erased_ok) {
+		/* Was an actual write failure,
+		 * so mark the block for retirement.*/
+		bi->needs_retiring = 1;
+		yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
+		  "**>> Block %d needs retiring", flash_block);
+	}
+
+	/* Delete the chunk */
+	yaffs_chunk_del(dev, nand_chunk, 1, __LINE__);
+	yaffs_skip_rest_of_block(dev);
+}
+
+/*
+ * Verification code
+ */
+
+/*
+ *  Simple hash function. Needs to have a reasonable spread
+ */
+
+static inline int yaffs_hash_fn(int n)
+{
+	n = abs(n);
+	return n % YAFFS_NOBJECT_BUCKETS;
+}
+
+/*
+ * Access functions to useful fake objects.
+ * Note that root might have a presence in NAND if permissions are set.
+ */
+
+struct yaffs_obj *yaffs_root(struct yaffs_dev *dev)
+{
+	return dev->root_dir;
+}
+
+struct yaffs_obj *yaffs_lost_n_found(struct yaffs_dev *dev)
+{
+	return dev->lost_n_found;
+}
+
+/*
+ *  Erased NAND checking functions
+ */
+
+int yaffs_check_ff(u8 *buffer, int n_bytes)
+{
+	/* Horrible, slow implementation */
+	while (n_bytes--) {
+		if (*buffer != 0xFF)
+			return 0;
+		buffer++;
+	}
+	return 1;
+}
+
+static int yaffs_check_chunk_erased(struct yaffs_dev *dev, int nand_chunk)
+{
+	int retval = YAFFS_OK;
+	u8 *data = yaffs_get_temp_buffer(dev, __LINE__);
+	struct yaffs_ext_tags tags;
+	int result;
+
+	result = yaffs_rd_chunk_tags_nand(dev, nand_chunk, data, &tags);
+
+	if (tags.ecc_result > YAFFS_ECC_RESULT_NO_ERROR)
+		retval = YAFFS_FAIL;
+
+	if (!yaffs_check_ff(data, dev->data_bytes_per_chunk) ||
+		tags.chunk_used) {
+		yaffs_trace(YAFFS_TRACE_NANDACCESS,
+			"Chunk %d not erased", nand_chunk);
+		retval = YAFFS_FAIL;
+	}
+
+	yaffs_release_temp_buffer(dev, data, __LINE__);
+
+	return retval;
+
+}
+
+static int yaffs_verify_chunk_written(struct yaffs_dev *dev,
+				      int nand_chunk,
+				      const u8 *data,
+				      struct yaffs_ext_tags *tags)
+{
+	int retval = YAFFS_OK;
+	struct yaffs_ext_tags temp_tags;
+	u8 *buffer = yaffs_get_temp_buffer(dev, __LINE__);
+	int result;
+
+	result = yaffs_rd_chunk_tags_nand(dev, nand_chunk, buffer, &temp_tags);
+	if (memcmp(buffer, data, dev->data_bytes_per_chunk) ||
+	    temp_tags.obj_id != tags->obj_id ||
+	    temp_tags.chunk_id != tags->chunk_id ||
+	    temp_tags.n_bytes != tags->n_bytes)
+		retval = YAFFS_FAIL;
+
+	yaffs_release_temp_buffer(dev, buffer, __LINE__);
+
+	return retval;
+}
+
+
+int yaffs_check_alloc_available(struct yaffs_dev *dev, int n_chunks)
+{
+	int reserved_chunks;
+	int reserved_blocks = dev->param.n_reserved_blocks;
+	int checkpt_blocks;
+
+	checkpt_blocks = yaffs_calc_checkpt_blocks_required(dev);
+
+	reserved_chunks =
+	    ((reserved_blocks + checkpt_blocks) * dev->param.chunks_per_block);
+
+	return (dev->n_free_chunks > (reserved_chunks + n_chunks));
+}
+
+static int yaffs_find_alloc_block(struct yaffs_dev *dev)
+{
+	int i;
+	struct yaffs_block_info *bi;
+
+	if (dev->n_erased_blocks < 1) {
+		/* Hoosterman we've got a problem.
+		 * Can't get space to gc
+		 */
+		yaffs_trace(YAFFS_TRACE_ERROR,
+		  "yaffs tragedy: no more erased blocks");
+
+		return -1;
+	}
+
+	/* Find an empty block. */
+
+	for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
+		dev->alloc_block_finder++;
+		if (dev->alloc_block_finder < dev->internal_start_block
+		    || dev->alloc_block_finder > dev->internal_end_block) {
+			dev->alloc_block_finder = dev->internal_start_block;
+		}
+
+		bi = yaffs_get_block_info(dev, dev->alloc_block_finder);
+
+		if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
+			bi->block_state = YAFFS_BLOCK_STATE_ALLOCATING;
+			dev->seq_number++;
+			bi->seq_number = dev->seq_number;
+			dev->n_erased_blocks--;
+			yaffs_trace(YAFFS_TRACE_ALLOCATE,
+			  "Allocated block %d, seq  %d, %d left" ,
+			   dev->alloc_block_finder, dev->seq_number,
+			   dev->n_erased_blocks);
+			return dev->alloc_block_finder;
+		}
+	}
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"yaffs tragedy: no more erased blocks, but there should have been %d",
+		dev->n_erased_blocks);
+
+	return -1;
+}
+
+static int yaffs_alloc_chunk(struct yaffs_dev *dev, int use_reserver,
+			     struct yaffs_block_info **block_ptr)
+{
+	int ret_val;
+	struct yaffs_block_info *bi;
+
+	if (dev->alloc_block < 0) {
+		/* Get next block to allocate off */
+		dev->alloc_block = yaffs_find_alloc_block(dev);
+		dev->alloc_page = 0;
+	}
+
+	if (!use_reserver && !yaffs_check_alloc_available(dev, 1)) {
+		/* No space unless we're allowed to use the reserve. */
+		return -1;
+	}
+
+	if (dev->n_erased_blocks < dev->param.n_reserved_blocks
+	    && dev->alloc_page == 0)
+		yaffs_trace(YAFFS_TRACE_ALLOCATE, "Allocating reserve");
+
+	/* Next page please.... */
+	if (dev->alloc_block >= 0) {
+		bi = yaffs_get_block_info(dev, dev->alloc_block);
+
+		ret_val = (dev->alloc_block * dev->param.chunks_per_block) +
+		    dev->alloc_page;
+		bi->pages_in_use++;
+		yaffs_set_chunk_bit(dev, dev->alloc_block, dev->alloc_page);
+
+		dev->alloc_page++;
+
+		dev->n_free_chunks--;
+
+		/* If the block is full set the state to full */
+		if (dev->alloc_page >= dev->param.chunks_per_block) {
+			bi->block_state = YAFFS_BLOCK_STATE_FULL;
+			dev->alloc_block = -1;
+		}
+
+		if (block_ptr)
+			*block_ptr = bi;
+
+		return ret_val;
+	}
+
+	yaffs_trace(YAFFS_TRACE_ERROR,
+		"!!!!!!!!! Allocator out !!!!!!!!!!!!!!!!!");
+
+	return -1;
+}
+
+static int yaffs_get_erased_chunks(struct yaffs_dev *dev)
+{
+	int n;
+
+	n = dev->n_erased_blocks * dev->param.chunks_per_block;
+
+	if (dev->alloc_block > 0)
+		n += (dev->param.chunks_per_block - dev->alloc_page);
+
+	return n;
+
+}
+
+/*
+ * yaffs_skip_rest_of_block() skips over the rest of the allocation block
+ * if we don't want to write to it.
+ */
+void yaffs_skip_rest_of_block(struct yaffs_dev *dev)
+{
+	if (dev->alloc_block > 0) {
+		struct yaffs_block_info *bi =
+		    yaffs_get_block_info(dev, dev->alloc_block);
+		if (bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING) {
+			bi->block_state = YAFFS_BLOCK_STATE_FULL;
+			dev->alloc_block = -1;
+		}
+	}
+}
+
+static int yaffs_write_new_chunk(struct yaffs_dev *dev,
+				 const u8 *data,
+				 struct yaffs_ext_tags *tags, int use_reserver)
+{
+	int attempts = 0;
+	int write_ok = 0;
+	int chunk;
+
+	yaffs2_checkpt_invalidate(dev);
+
+	do {
+		struct yaffs_block_info *bi = 0;
+		int erased_ok = 0;
+
+		chunk = yaffs_alloc_chunk(dev, use_reserver, &bi);
+		if (chunk < 0) {
+			/* no space */
+			break;
+		}
+
+		/* First check this chunk is erased, if it needs
+		 * checking.  The checking policy (unless forced
+		 * always on) is as follows:
+		 *
+		 * Check the first page we try to write in a block.
+		 * If the check passes then we don't need to check any
+		 * more.        If the check fails, we check again...
+		 * If the block has been erased, we don't need to check.
+		 *
+		 * However, if the block has been prioritised for gc,
+		 * then we think there might be something odd about
+		 * this block and stop using it.
+		 *
+		 * Rationale: We should only ever see chunks that have
+		 * not been erased if there was a partially written
+		 * chunk due to power loss.  This checking policy should
+		 * catch that case with very few checks and thus save a
+		 * lot of checks that are most likely not needed.
+		 *
+		 * Mods to the above
+		 * If an erase check fails or the write fails we skip the
+		 * rest of the block.
+		 */
+
+		/* let's give it a try */
+		attempts++;
+
+		if (dev->param.always_check_erased)
+			bi->skip_erased_check = 0;
+
+		if (!bi->skip_erased_check) {
+			erased_ok = yaffs_check_chunk_erased(dev, chunk);
+			if (erased_ok != YAFFS_OK) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+				  "**>> yaffs chunk %d was not erased",
+				  chunk);
+
+				/* If not erased, delete this one,
+				 * skip rest of block and
+				 * try another chunk */
+				yaffs_chunk_del(dev, chunk, 1, __LINE__);
+				yaffs_skip_rest_of_block(dev);
+				continue;
+			}
+		}
+
+		write_ok = yaffs_wr_chunk_tags_nand(dev, chunk, data, tags);
+
+		if (!bi->skip_erased_check)
+			write_ok =
+			    yaffs_verify_chunk_written(dev, chunk, data, tags);
+
+		if (write_ok != YAFFS_OK) {
+			/* Clean up aborted write, skip to next block and
+			 * try another chunk */
+			yaffs_handle_chunk_wr_error(dev, chunk, erased_ok);
+			continue;
+		}
+
+		bi->skip_erased_check = 1;
+
+		/* Copy the data into the robustification buffer */
+		yaffs_handle_chunk_wr_ok(dev, chunk, data, tags);
+
+	} while (write_ok != YAFFS_OK &&
+		 (yaffs_wr_attempts <= 0 || attempts <= yaffs_wr_attempts));
+
+	if (!write_ok)
+		chunk = -1;
+
+	if (attempts > 1) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"**>> yaffs write required %d attempts",
+			attempts);
+		dev->n_retired_writes += (attempts - 1);
+	}
+
+	return chunk;
+}
+
+/*
+ * Block retiring for handling a broken block.
+ */
+
+static void yaffs_retire_block(struct yaffs_dev *dev, int flash_block)
+{
+	struct yaffs_block_info *bi = yaffs_get_block_info(dev, flash_block);
+
+	yaffs2_checkpt_invalidate(dev);
+
+	yaffs2_clear_oldest_dirty_seq(dev, bi);
+
+	if (yaffs_mark_bad(dev, flash_block) != YAFFS_OK) {
+		if (yaffs_erase_block(dev, flash_block) != YAFFS_OK) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"yaffs: Failed to mark bad and erase block %d",
+				flash_block);
+		} else {
+			struct yaffs_ext_tags tags;
+			int chunk_id =
+			    flash_block * dev->param.chunks_per_block;
+
+			u8 *buffer = yaffs_get_temp_buffer(dev, __LINE__);
+
+			memset(buffer, 0xff, dev->data_bytes_per_chunk);
+			yaffs_init_tags(&tags);
+			tags.seq_number = YAFFS_SEQUENCE_BAD_BLOCK;
+			if (dev->param.write_chunk_tags_fn(dev, chunk_id -
+							   dev->chunk_offset,
+							   buffer,
+							   &tags) != YAFFS_OK)
+				yaffs_trace(YAFFS_TRACE_ALWAYS,
+					"yaffs: Failed to write bad block marker to block %d",
+					flash_block);
+
+			yaffs_release_temp_buffer(dev, buffer, __LINE__);
+		}
+	}
+
+	bi->block_state = YAFFS_BLOCK_STATE_DEAD;
+	bi->gc_prioritise = 0;
+	bi->needs_retiring = 0;
+
+	dev->n_retired_blocks++;
+}
+
+/*---------------- Name handling functions ------------*/
+
+static u16 yaffs_calc_name_sum(const YCHAR *name)
+{
+	u16 sum = 0;
+	u16 i = 1;
+	const YUCHAR *bname = (const YUCHAR *)name;
+
+	if (bname) {
+		while ((*bname) && (i < (YAFFS_MAX_NAME_LENGTH / 2))) {
+
+			/* 0x1f mask is case insensitive */
+			sum += ((*bname) & 0x1f) * i;
+			i++;
+			bname++;
+		}
+	}
+	return sum;
+}
+
+void yaffs_set_obj_name(struct yaffs_obj *obj, const YCHAR * name)
+{
+#ifndef CONFIG_YAFFS_NO_SHORT_NAMES
+	memset(obj->short_name, 0, sizeof(obj->short_name));
+	if (name &&
+		strnlen(name, YAFFS_SHORT_NAME_LENGTH + 1) <=
+		YAFFS_SHORT_NAME_LENGTH)
+		strcpy(obj->short_name, name);
+	else
+		obj->short_name[0] = _Y('\0');
+#endif
+	obj->sum = yaffs_calc_name_sum(name);
+}
+
+void yaffs_set_obj_name_from_oh(struct yaffs_obj *obj,
+				const struct yaffs_obj_hdr *oh)
+{
+#ifdef CONFIG_YAFFS_AUTO_UNICODE
+	YCHAR tmp_name[YAFFS_MAX_NAME_LENGTH + 1];
+	memset(tmp_name, 0, sizeof(tmp_name));
+	yaffs_load_name_from_oh(obj->my_dev, tmp_name, oh->name,
+				YAFFS_MAX_NAME_LENGTH + 1);
+	yaffs_set_obj_name(obj, tmp_name);
+#else
+	yaffs_set_obj_name(obj, oh->name);
+#endif
+}
+
+/*-------------------- TNODES -------------------
+
+ * List of spare tnodes
+ * The list is hooked together using the first pointer
+ * in the tnode.
+ */
+
+struct yaffs_tnode *yaffs_get_tnode(struct yaffs_dev *dev)
+{
+	struct yaffs_tnode *tn = yaffs_alloc_raw_tnode(dev);
+
+	if (tn) {
+		memset(tn, 0, dev->tnode_size);
+		dev->n_tnodes++;
+	}
+
+	dev->checkpoint_blocks_required = 0;	/* force recalculation */
+
+	return tn;
+}
+
+/* FreeTnode frees up a tnode and puts it back on the free list */
+static void yaffs_free_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn)
+{
+	yaffs_free_raw_tnode(dev, tn);
+	dev->n_tnodes--;
+	dev->checkpoint_blocks_required = 0;	/* force recalculation */
+}
+
+static void yaffs_deinit_tnodes_and_objs(struct yaffs_dev *dev)
+{
+	yaffs_deinit_raw_tnodes_and_objs(dev);
+	dev->n_obj = 0;
+	dev->n_tnodes = 0;
+}
+
+void yaffs_load_tnode_0(struct yaffs_dev *dev, struct yaffs_tnode *tn,
+			unsigned pos, unsigned val)
+{
+	u32 *map = (u32 *) tn;
+	u32 bit_in_map;
+	u32 bit_in_word;
+	u32 word_in_map;
+	u32 mask;
+
+	pos &= YAFFS_TNODES_LEVEL0_MASK;
+	val >>= dev->chunk_grp_bits;
+
+	bit_in_map = pos * dev->tnode_width;
+	word_in_map = bit_in_map / 32;
+	bit_in_word = bit_in_map & (32 - 1);
+
+	mask = dev->tnode_mask << bit_in_word;
+
+	map[word_in_map] &= ~mask;
+	map[word_in_map] |= (mask & (val << bit_in_word));
+
+	if (dev->tnode_width > (32 - bit_in_word)) {
+		bit_in_word = (32 - bit_in_word);
+		word_in_map++;;
+		mask =
+		    dev->tnode_mask >> bit_in_word;
+		map[word_in_map] &= ~mask;
+		map[word_in_map] |= (mask & (val >> bit_in_word));
+	}
+}
+
+u32 yaffs_get_group_base(struct yaffs_dev *dev, struct yaffs_tnode *tn,
+			 unsigned pos)
+{
+	u32 *map = (u32 *) tn;
+	u32 bit_in_map;
+	u32 bit_in_word;
+	u32 word_in_map;
+	u32 val;
+
+	pos &= YAFFS_TNODES_LEVEL0_MASK;
+
+	bit_in_map = pos * dev->tnode_width;
+	word_in_map = bit_in_map / 32;
+	bit_in_word = bit_in_map & (32 - 1);
+
+	val = map[word_in_map] >> bit_in_word;
+
+	if (dev->tnode_width > (32 - bit_in_word)) {
+		bit_in_word = (32 - bit_in_word);
+		word_in_map++;;
+		val |= (map[word_in_map] << bit_in_word);
+	}
+
+	val &= dev->tnode_mask;
+	val <<= dev->chunk_grp_bits;
+
+	return val;
+}
+
+/* ------------------- End of individual tnode manipulation -----------------*/
+
+/* ---------Functions to manipulate the look-up tree (made up of tnodes) ------
+ * The look up tree is represented by the top tnode and the number of top_level
+ * in the tree. 0 means only the level 0 tnode is in the tree.
+ */
+
+/* FindLevel0Tnode finds the level 0 tnode, if one exists. */
+struct yaffs_tnode *yaffs_find_tnode_0(struct yaffs_dev *dev,
+				       struct yaffs_file_var *file_struct,
+				       u32 chunk_id)
+{
+	struct yaffs_tnode *tn = file_struct->top;
+	u32 i;
+	int required_depth;
+	int level = file_struct->top_level;
+
+	dev = dev;
+
+	/* Check sane level and chunk Id */
+	if (level < 0 || level > YAFFS_TNODES_MAX_LEVEL)
+		return NULL;
+
+	if (chunk_id > YAFFS_MAX_CHUNK_ID)
+		return NULL;
+
+	/* First check we're tall enough (ie enough top_level) */
+
+	i = chunk_id >> YAFFS_TNODES_LEVEL0_BITS;
+	required_depth = 0;
+	while (i) {
+		i >>= YAFFS_TNODES_INTERNAL_BITS;
+		required_depth++;
+	}
+
+	if (required_depth > file_struct->top_level)
+		return NULL;	/* Not tall enough, so we can't find it */
+
+	/* Traverse down to level 0 */
+	while (level > 0 && tn) {
+		tn = tn->internal[(chunk_id >>
+				   (YAFFS_TNODES_LEVEL0_BITS +
+				    (level - 1) *
+				    YAFFS_TNODES_INTERNAL_BITS)) &
+				  YAFFS_TNODES_INTERNAL_MASK];
+		level--;
+	}
+
+	return tn;
+}
+
+/* add_find_tnode_0 finds the level 0 tnode if it exists,
+ * otherwise first expands the tree.
+ * This happens in two steps:
+ *  1. If the tree isn't tall enough, then make it taller.
+ *  2. Scan down the tree towards the level 0 tnode adding tnodes if required.
+ *
+ * Used when modifying the tree.
+ *
+ *  If the tn argument is NULL, then a fresh tnode will be added otherwise the
+ *  specified tn will be plugged into the ttree.
+ */
+
+struct yaffs_tnode *yaffs_add_find_tnode_0(struct yaffs_dev *dev,
+					   struct yaffs_file_var *file_struct,
+					   u32 chunk_id,
+					   struct yaffs_tnode *passed_tn)
+{
+	int required_depth;
+	int i;
+	int l;
+	struct yaffs_tnode *tn;
+	u32 x;
+
+	/* Check sane level and page Id */
+	if (file_struct->top_level < 0
+	    || file_struct->top_level > YAFFS_TNODES_MAX_LEVEL)
+		return NULL;
+
+	if (chunk_id > YAFFS_MAX_CHUNK_ID)
+		return NULL;
+
+	/* First check we're tall enough (ie enough top_level) */
+
+	x = chunk_id >> YAFFS_TNODES_LEVEL0_BITS;
+	required_depth = 0;
+	while (x) {
+		x >>= YAFFS_TNODES_INTERNAL_BITS;
+		required_depth++;
+	}
+
+	if (required_depth > file_struct->top_level) {
+		/* Not tall enough, gotta make the tree taller */
+		for (i = file_struct->top_level; i < required_depth; i++) {
+
+			tn = yaffs_get_tnode(dev);
+
+			if (tn) {
+				tn->internal[0] = file_struct->top;
+				file_struct->top = tn;
+				file_struct->top_level++;
+			} else {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"yaffs: no more tnodes");
+				return NULL;
+			}
+		}
+	}
+
+	/* Traverse down to level 0, adding anything we need */
+
+	l = file_struct->top_level;
+	tn = file_struct->top;
+
+	if (l > 0) {
+		while (l > 0 && tn) {
+			x = (chunk_id >>
+			     (YAFFS_TNODES_LEVEL0_BITS +
+			      (l - 1) * YAFFS_TNODES_INTERNAL_BITS)) &
+			    YAFFS_TNODES_INTERNAL_MASK;
+
+			if ((l > 1) && !tn->internal[x]) {
+				/* Add missing non-level-zero tnode */
+				tn->internal[x] = yaffs_get_tnode(dev);
+				if (!tn->internal[x])
+					return NULL;
+			} else if (l == 1) {
+				/* Looking from level 1 at level 0 */
+				if (passed_tn) {
+					/* If we already have one, release it */
+					if (tn->internal[x])
+						yaffs_free_tnode(dev,
+							tn->internal[x]);
+					tn->internal[x] = passed_tn;
+
+				} else if (!tn->internal[x]) {
+					/* Don't have one, none passed in */
+					tn->internal[x] = yaffs_get_tnode(dev);
+					if (!tn->internal[x])
+						return NULL;
+				}
+			}
+
+			tn = tn->internal[x];
+			l--;
+		}
+	} else {
+		/* top is level 0 */
+		if (passed_tn) {
+			memcpy(tn, passed_tn,
+			       (dev->tnode_width * YAFFS_NTNODES_LEVEL0) / 8);
+			yaffs_free_tnode(dev, passed_tn);
+		}
+	}
+
+	return tn;
+}
+
+static int yaffs_tags_match(const struct yaffs_ext_tags *tags, int obj_id,
+			    int chunk_obj)
+{
+	return (tags->chunk_id == chunk_obj &&
+		tags->obj_id == obj_id && !tags->is_deleted) ? 1 : 0;
+
+}
+
+static int yaffs_find_chunk_in_group(struct yaffs_dev *dev, int the_chunk,
+					struct yaffs_ext_tags *tags, int obj_id,
+					int inode_chunk)
+{
+	int j;
+
+	for (j = 0; the_chunk && j < dev->chunk_grp_size; j++) {
+		if (yaffs_check_chunk_bit
+		    (dev, the_chunk / dev->param.chunks_per_block,
+		     the_chunk % dev->param.chunks_per_block)) {
+
+			if (dev->chunk_grp_size == 1)
+				return the_chunk;
+			else {
+				yaffs_rd_chunk_tags_nand(dev, the_chunk, NULL,
+							 tags);
+				if (yaffs_tags_match(tags,
+							obj_id, inode_chunk)) {
+					/* found it; */
+					return the_chunk;
+				}
+			}
+		}
+		the_chunk++;
+	}
+	return -1;
+}
+
+static int yaffs_find_chunk_in_file(struct yaffs_obj *in, int inode_chunk,
+				    struct yaffs_ext_tags *tags)
+{
+	/*Get the Tnode, then get the level 0 offset chunk offset */
+	struct yaffs_tnode *tn;
+	int the_chunk = -1;
+	struct yaffs_ext_tags local_tags;
+	int ret_val = -1;
+	struct yaffs_dev *dev = in->my_dev;
+
+	if (!tags) {
+		/* Passed a NULL, so use our own tags space */
+		tags = &local_tags;
+	}
+
+	tn = yaffs_find_tnode_0(dev, &in->variant.file_variant, inode_chunk);
+
+	if (tn) {
+		the_chunk = yaffs_get_group_base(dev, tn, inode_chunk);
+
+		ret_val =
+		    yaffs_find_chunk_in_group(dev, the_chunk, tags, in->obj_id,
+					      inode_chunk);
+	}
+	return ret_val;
+}
+
+static int yaffs_find_del_file_chunk(struct yaffs_obj *in, int inode_chunk,
+				     struct yaffs_ext_tags *tags)
+{
+	/* Get the Tnode, then get the level 0 offset chunk offset */
+	struct yaffs_tnode *tn;
+	int the_chunk = -1;
+	struct yaffs_ext_tags local_tags;
+	struct yaffs_dev *dev = in->my_dev;
+	int ret_val = -1;
+
+	if (!tags) {
+		/* Passed a NULL, so use our own tags space */
+		tags = &local_tags;
+	}
+
+	tn = yaffs_find_tnode_0(dev, &in->variant.file_variant, inode_chunk);
+
+	if (tn) {
+
+		the_chunk = yaffs_get_group_base(dev, tn, inode_chunk);
+
+		ret_val =
+		    yaffs_find_chunk_in_group(dev, the_chunk, tags, in->obj_id,
+					      inode_chunk);
+
+		/* Delete the entry in the filestructure (if found) */
+		if (ret_val != -1)
+			yaffs_load_tnode_0(dev, tn, inode_chunk, 0);
+	}
+
+	return ret_val;
+}
+
+int yaffs_put_chunk_in_file(struct yaffs_obj *in, int inode_chunk,
+			    int nand_chunk, int in_scan)
+{
+	/* NB in_scan is zero unless scanning.
+	 * For forward scanning, in_scan is > 0;
+	 * for backward scanning in_scan is < 0
+	 *
+	 * nand_chunk = 0 is a dummy insert to make sure the tnodes are there.
+	 */
+
+	struct yaffs_tnode *tn;
+	struct yaffs_dev *dev = in->my_dev;
+	int existing_cunk;
+	struct yaffs_ext_tags existing_tags;
+	struct yaffs_ext_tags new_tags;
+	unsigned existing_serial, new_serial;
+
+	if (in->variant_type != YAFFS_OBJECT_TYPE_FILE) {
+		/* Just ignore an attempt at putting a chunk into a non-file
+		 * during scanning.
+		 * If it is not during Scanning then something went wrong!
+		 */
+		if (!in_scan) {
+			yaffs_trace(YAFFS_TRACE_ERROR,
+				"yaffs tragedy:attempt to put data chunk into a non-file"
+				);
+			YBUG();
+		}
+
+		yaffs_chunk_del(dev, nand_chunk, 1, __LINE__);
+		return YAFFS_OK;
+	}
+
+	tn = yaffs_add_find_tnode_0(dev,
+				    &in->variant.file_variant,
+				    inode_chunk, NULL);
+	if (!tn)
+		return YAFFS_FAIL;
+
+	if (!nand_chunk)
+		/* Dummy insert, bail now */
+		return YAFFS_OK;
+
+	existing_cunk = yaffs_get_group_base(dev, tn, inode_chunk);
+
+	if (in_scan != 0) {
+		/* If we're scanning then we need to test for duplicates
+		 * NB This does not need to be efficient since it should only
+		 * happen when the power fails during a write, then only one
+		 * chunk should ever be affected.
+		 *
+		 * Correction for YAFFS2: This could happen quite a lot and we
+		 * need to think about efficiency! TODO
+		 * Update: For backward scanning we don't need to re-read tags
+		 * so this is quite cheap.
+		 */
+
+		if (existing_cunk > 0) {
+			/* NB Right now existing chunk will not be real
+			 * chunk_id if the chunk group size > 1
+			 * thus we have to do a FindChunkInFile to get the
+			 * real chunk id.
+			 *
+			 * We have a duplicate now we need to decide which
+			 * one to use:
+			 *
+			 * Backwards scanning YAFFS2: The old one is what
+			 * we use, dump the new one.
+			 * YAFFS1: Get both sets of tags and compare serial
+			 * numbers.
+			 */
+
+			if (in_scan > 0) {
+				/* Only do this for forward scanning */
+				yaffs_rd_chunk_tags_nand(dev,
+							 nand_chunk,
+							 NULL, &new_tags);
+
+				/* Do a proper find */
+				existing_cunk =
+				    yaffs_find_chunk_in_file(in, inode_chunk,
+							     &existing_tags);
+			}
+
+			if (existing_cunk <= 0) {
+				/*Hoosterman - how did this happen? */
+
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					"yaffs tragedy: existing chunk < 0 in scan"
+					);
+
+			}
+
+			/* NB The deleted flags should be false, otherwise
+			 * the chunks will not be loaded during a scan
+			 */
+
+			if (in_scan > 0) {
+				new_serial = new_tags.serial_number;
+				existing_serial = existing_tags.serial_number;
+			}
+
+			if ((in_scan > 0) &&
+			    (existing_cunk <= 0 ||
+			     ((existing_serial + 1) & 3) == new_serial)) {
+				/* Forward scanning.
+				 * Use new
+				 * Delete the old one and drop through to
+				 * update the tnode
+				 */
+				yaffs_chunk_del(dev, existing_cunk, 1,
+						__LINE__);
+			} else {
+				/* Backward scanning or we want to use the
+				 * existing one
+				 * Delete the new one and return early so that
+				 * the tnode isn't changed
+				 */
+				yaffs_chunk_del(dev, nand_chunk, 1, __LINE__);
+				return YAFFS_OK;
+			}
+		}
+
+	}
+
+	if (existing_cunk == 0)
+		in->n_data_chunks++;
+
+	yaffs_load_tnode_0(dev, tn, inode_chunk, nand_chunk);
+
+	return YAFFS_OK;
+}
+
+static void yaffs_soft_del_chunk(struct yaffs_dev *dev, int chunk)
+{
+	struct yaffs_block_info *the_block;
+	unsigned block_no;
+
+	yaffs_trace(YAFFS_TRACE_DELETION, "soft delete chunk %d", chunk);
+
+	block_no = chunk / dev->param.chunks_per_block;
+	the_block = yaffs_get_block_info(dev, block_no);
+	if (the_block) {
+		the_block->soft_del_pages++;
+		dev->n_free_chunks++;
+		yaffs2_update_oldest_dirty_seq(dev, block_no, the_block);
+	}
+}
+
+/* SoftDeleteWorker scans backwards through the tnode tree and soft deletes all
+ * the chunks in the file.
+ * All soft deleting does is increment the block's softdelete count and pulls
+ * the chunk out of the tnode.
+ * Thus, essentially this is the same as DeleteWorker except that the chunks
+ * are soft deleted.
+ */
+
+static int yaffs_soft_del_worker(struct yaffs_obj *in, struct yaffs_tnode *tn,
+				 u32 level, int chunk_offset)
+{
+	int i;
+	int the_chunk;
+	int all_done = 1;
+	struct yaffs_dev *dev = in->my_dev;
+
+	if (tn) {
+		if (level > 0) {
+			for (i = YAFFS_NTNODES_INTERNAL - 1;
+				all_done && i >= 0;
+				i--) {
+				if (tn->internal[i]) {
+					all_done =
+					    yaffs_soft_del_worker(in,
+						tn->internal[i],
+						level - 1,
+						(chunk_offset <<
+						YAFFS_TNODES_INTERNAL_BITS)
+						+ i);
+					if (all_done) {
+						yaffs_free_tnode(dev,
+							tn->internal[i]);
+						tn->internal[i] = NULL;
+					} else {
+						/* Can this happen? */
+					}
+				}
+			}
+			return (all_done) ? 1 : 0;
+		} else if (level == 0) {
+			for (i = YAFFS_NTNODES_LEVEL0 - 1; i >= 0; i--) {
+				the_chunk = yaffs_get_group_base(dev, tn, i);
+				if (the_chunk) {
+					yaffs_soft_del_chunk(dev, the_chunk);
+					yaffs_load_tnode_0(dev, tn, i, 0);
+				}
+			}
+			return 1;
+		}
+	}
+	return 1;
+}
+
+static void yaffs_remove_obj_from_dir(struct yaffs_obj *obj)
+{
+	struct yaffs_dev *dev = obj->my_dev;
+	struct yaffs_obj *parent;
+
+	yaffs_verify_obj_in_dir(obj);
+	parent = obj->parent;
+
+	yaffs_verify_dir(parent);
+
+	if (dev && dev->param.remove_obj_fn)
+		dev->param.remove_obj_fn(obj);
+
+	list_del_init(&obj->siblings);
+	obj->parent = NULL;
+
+	yaffs_verify_dir(parent);
+}
+
+void yaffs_add_obj_to_dir(struct yaffs_obj *directory, struct yaffs_obj *obj)
+{
+	if (!directory) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"tragedy: Trying to add an object to a null pointer directory"
+			);
+		YBUG();
+		return;
+	}
+	if (directory->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"tragedy: Trying to add an object to a non-directory"
+			);
+		YBUG();
+	}
+
+	if (obj->siblings.prev == NULL) {
+		/* Not initialised */
+		YBUG();
+	}
+
+	yaffs_verify_dir(directory);
+
+	yaffs_remove_obj_from_dir(obj);
+
+	/* Now add it */
+	list_add(&obj->siblings, &directory->variant.dir_variant.children);
+	obj->parent = directory;
+
+	if (directory == obj->my_dev->unlinked_dir
+	    || directory == obj->my_dev->del_dir) {
+		obj->unlinked = 1;
+		obj->my_dev->n_unlinked_files++;
+		obj->rename_allowed = 0;
+	}
+
+	yaffs_verify_dir(directory);
+	yaffs_verify_obj_in_dir(obj);
+}
+
+static int yaffs_change_obj_name(struct yaffs_obj *obj,
+				 struct yaffs_obj *new_dir,
+				 const YCHAR *new_name, int force, int shadows)
+{
+	int unlink_op;
+	int del_op;
+	struct yaffs_obj *existing_target;
+
+	if (new_dir == NULL)
+		new_dir = obj->parent;	/* use the old directory */
+
+	if (new_dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"tragedy: yaffs_change_obj_name: new_dir is not a directory"
+			);
+		YBUG();
+	}
+
+	/* TODO: Do we need this different handling for YAFFS2 and YAFFS1?? */
+	if (obj->my_dev->param.is_yaffs2)
+		unlink_op = (new_dir == obj->my_dev->unlinked_dir);
+	else
+		unlink_op = (new_dir == obj->my_dev->unlinked_dir
+			     && obj->variant_type == YAFFS_OBJECT_TYPE_FILE);
+
+	del_op = (new_dir == obj->my_dev->del_dir);
+
+	existing_target = yaffs_find_by_name(new_dir, new_name);
+
+	/* If the object is a file going into the unlinked directory,
+	 *   then it is OK to just stuff it in since duplicate names are OK.
+	 *   else only proceed if the new name does not exist and we're putting
+	 *   it into a directory.
+	 */
+	if ((unlink_op ||
+	     del_op ||
+	     force ||
+	     (shadows > 0) ||
+	     !existing_target) &&
+	    new_dir->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY) {
+		yaffs_set_obj_name(obj, new_name);
+		obj->dirty = 1;
+
+		yaffs_add_obj_to_dir(new_dir, obj);
+
+		if (unlink_op)
+			obj->unlinked = 1;
+
+		/* If it is a deletion then we mark it as a shrink for gc  */
+		if (yaffs_update_oh(obj, new_name, 0, del_op, shadows, NULL) >=
+		    0)
+			return YAFFS_OK;
+	}
+	return YAFFS_FAIL;
+}
+
+/*------------------------ Short Operations Cache ------------------------------
+ *   In many situations where there is no high level buffering  a lot of
+ *   reads might be short sequential reads, and a lot of writes may be short
+ *   sequential writes. eg. scanning/writing a jpeg file.
+ *   In these cases, a short read/write cache can provide a huge perfomance
+ *   benefit with dumb-as-a-rock code.
+ *   In Linux, the page cache provides read buffering and the short op cache
+ *   provides write buffering.
+ *
+ *   There are a small number (~10) of cache chunks per device so that we don't
+ *   need a very intelligent search.
+ */
+
+static int yaffs_obj_cache_dirty(struct yaffs_obj *obj)
+{
+	struct yaffs_dev *dev = obj->my_dev;
+	int i;
+	struct yaffs_cache *cache;
+	int n_caches = obj->my_dev->param.n_caches;
+
+	for (i = 0; i < n_caches; i++) {
+		cache = &dev->cache[i];
+		if (cache->object == obj && cache->dirty)
+			return 1;
+	}
+
+	return 0;
+}
+
+static void yaffs_flush_file_cache(struct yaffs_obj *obj)
+{
+	struct yaffs_dev *dev = obj->my_dev;
+	int lowest = -99;	/* Stop compiler whining. */
+	int i;
+	struct yaffs_cache *cache;
+	int chunk_written = 0;
+	int n_caches = obj->my_dev->param.n_caches;
+
+	if (n_caches > 0) {
+		do {
+			cache = NULL;
+
+			/* Find the lowest dirty chunk for this object */
+			for (i = 0; i < n_caches; i++) {
+				if (dev->cache[i].object == obj &&
+				    dev->cache[i].dirty) {
+					if (!cache
+					    || dev->cache[i].chunk_id <
+					    lowest) {
+						cache = &dev->cache[i];
+						lowest = cache->chunk_id;
+					}
+				}
+			}
+
+			if (cache && !cache->locked) {
+				/* Write it out and free it up */
+				chunk_written =
+				    yaffs_wr_data_obj(cache->object,
+						      cache->chunk_id,
+						      cache->data,
+						      cache->n_bytes, 1);
+				cache->dirty = 0;
+				cache->object = NULL;
+			}
+		} while (cache && chunk_written > 0);
+
+		if (cache)
+			/* Hoosterman, disk full while writing cache out. */
+			yaffs_trace(YAFFS_TRACE_ERROR,
+				"yaffs tragedy: no space during cache write");
+	}
+}
+
+/*yaffs_flush_whole_cache(dev)
+ *
+ *
+ */
+
+void yaffs_flush_whole_cache(struct yaffs_dev *dev)
+{
+	struct yaffs_obj *obj;
+	int n_caches = dev->param.n_caches;
+	int i;
+
+	/* Find a dirty object in the cache and flush it...
+	 * until there are no further dirty objects.
+	 */
+	do {
+		obj = NULL;
+		for (i = 0; i < n_caches && !obj; i++) {
+			if (dev->cache[i].object && dev->cache[i].dirty)
+				obj = dev->cache[i].object;
+		}
+		if (obj)
+			yaffs_flush_file_cache(obj);
+	} while (obj);
+
+}
+
+/* Grab us a cache chunk for use.
+ * First look for an empty one.
+ * Then look for the least recently used non-dirty one.
+ * Then look for the least recently used dirty one...., flush and look again.
+ */
+static struct yaffs_cache *yaffs_grab_chunk_worker(struct yaffs_dev *dev)
+{
+	int i;
+
+	if (dev->param.n_caches > 0) {
+		for (i = 0; i < dev->param.n_caches; i++) {
+			if (!dev->cache[i].object)
+				return &dev->cache[i];
+		}
+	}
+	return NULL;
+}
+
+static struct yaffs_cache *yaffs_grab_chunk_cache(struct yaffs_dev *dev)
+{
+	struct yaffs_cache *cache;
+	struct yaffs_obj *the_obj;
+	int usage;
+	int i;
+	int pushout;
+
+	if (dev->param.n_caches > 0) {
+		/* Try find a non-dirty one... */
+
+		cache = yaffs_grab_chunk_worker(dev);
+
+		if (!cache) {
+			/* They were all dirty, find the LRU object and flush
+			 * its cache, then  find again.
+			 * NB what's here is not very accurate,
+			 * we actually flush the object with the LRU chunk.
+			 */
+
+			/* With locking we can't assume we can use entry zero,
+			 * Set the_obj to a valid pointer for Coverity. */
+
+			the_obj = dev->cache[0].object;
+			usage = -1;
+			cache = NULL;
+			pushout = -1;
+
+			for (i = 0; i < dev->param.n_caches; i++) {
+				if (dev->cache[i].object &&
+				    !dev->cache[i].locked &&
+				    (dev->cache[i].last_use < usage
+				     || !cache)) {
+					usage = dev->cache[i].last_use;
+					the_obj = dev->cache[i].object;
+					cache = &dev->cache[i];
+					pushout = i;
+				}
+			}
+
+			if (!cache || cache->dirty) {
+				/* Flush and try again */
+				yaffs_flush_file_cache(the_obj);
+				cache = yaffs_grab_chunk_worker(dev);
+			}
+		}
+		return cache;
+	} else {
+		return NULL;
+	}
+}
+
+/* Find a cached chunk */
+static struct yaffs_cache *yaffs_find_chunk_cache(const struct yaffs_obj *obj,
+						  int chunk_id)
+{
+	struct yaffs_dev *dev = obj->my_dev;
+	int i;
+
+	if (dev->param.n_caches > 0) {
+		for (i = 0; i < dev->param.n_caches; i++) {
+			if (dev->cache[i].object == obj &&
+			    dev->cache[i].chunk_id == chunk_id) {
+				dev->cache_hits++;
+
+				return &dev->cache[i];
+			}
+		}
+	}
+	return NULL;
+}
+
+/* Mark the chunk for the least recently used algorithym */
+static void yaffs_use_cache(struct yaffs_dev *dev, struct yaffs_cache *cache,
+			    int is_write)
+{
+	if (dev->param.n_caches > 0) {
+		if (dev->cache_last_use < 0 ||
+			dev->cache_last_use > 100000000) {
+			/* Reset the cache usages */
+			int i;
+			for (i = 1; i < dev->param.n_caches; i++)
+				dev->cache[i].last_use = 0;
+
+			dev->cache_last_use = 0;
+		}
+		dev->cache_last_use++;
+		cache->last_use = dev->cache_last_use;
+
+		if (is_write)
+			cache->dirty = 1;
+	}
+}
+
+/* Invalidate a single cache page.
+ * Do this when a whole page gets written,
+ * ie the short cache for this page is no longer valid.
+ */
+static void yaffs_invalidate_chunk_cache(struct yaffs_obj *object, int chunk_id)
+{
+	if (object->my_dev->param.n_caches > 0) {
+		struct yaffs_cache *cache =
+		    yaffs_find_chunk_cache(object, chunk_id);
+
+		if (cache)
+			cache->object = NULL;
+	}
+}
+
+/* Invalidate all the cache pages associated with this object
+ * Do this whenever ther file is deleted or resized.
+ */
+static void yaffs_invalidate_whole_cache(struct yaffs_obj *in)
+{
+	int i;
+	struct yaffs_dev *dev = in->my_dev;
+
+	if (dev->param.n_caches > 0) {
+		/* Invalidate it. */
+		for (i = 0; i < dev->param.n_caches; i++) {
+			if (dev->cache[i].object == in)
+				dev->cache[i].object = NULL;
+		}
+	}
+}
+
+static void yaffs_unhash_obj(struct yaffs_obj *obj)
+{
+	int bucket;
+	struct yaffs_dev *dev = obj->my_dev;
+
+	/* If it is still linked into the bucket list, free from the list */
+	if (!list_empty(&obj->hash_link)) {
+		list_del_init(&obj->hash_link);
+		bucket = yaffs_hash_fn(obj->obj_id);
+		dev->obj_bucket[bucket].count--;
+	}
+}
+
+/*  FreeObject frees up a Object and puts it back on the free list */
+static void yaffs_free_obj(struct yaffs_obj *obj)
+{
+	struct yaffs_dev *dev = obj->my_dev;
+
+	yaffs_trace(YAFFS_TRACE_OS, "FreeObject %p inode %p",
+		obj, obj->my_inode);
+
+	if (!obj) {
+		YBUG();
+		return;
+	}
+	if (obj->parent)
+		YBUG();
+	if (!list_empty(&obj->siblings))
+		YBUG();
+
+	if (obj->my_inode) {
+		/* We're still hooked up to a cached inode.
+		 * Don't delete now, but mark for later deletion
+		 */
+		obj->defered_free = 1;
+		return;
+	}
+
+	yaffs_unhash_obj(obj);
+
+	yaffs_free_raw_obj(dev, obj);
+	dev->n_obj--;
+	dev->checkpoint_blocks_required = 0;	/* force recalculation */
+}
+
+void yaffs_handle_defered_free(struct yaffs_obj *obj)
+{
+	if (obj->defered_free)
+		yaffs_free_obj(obj);
+}
+
+static int yaffs_generic_obj_del(struct yaffs_obj *in)
+{
+	/* Iinvalidate the file's data in the cache, without flushing. */
+	yaffs_invalidate_whole_cache(in);
+
+	if (in->my_dev->param.is_yaffs2 && in->parent != in->my_dev->del_dir) {
+		/* Move to unlinked directory so we have a deletion record */
+		yaffs_change_obj_name(in, in->my_dev->del_dir, _Y("deleted"), 0,
+				      0);
+	}
+
+	yaffs_remove_obj_from_dir(in);
+	yaffs_chunk_del(in->my_dev, in->hdr_chunk, 1, __LINE__);
+	in->hdr_chunk = 0;
+
+	yaffs_free_obj(in);
+	return YAFFS_OK;
+
+}
+
+static void yaffs_soft_del_file(struct yaffs_obj *obj)
+{
+	if (obj->deleted &&
+	    obj->variant_type == YAFFS_OBJECT_TYPE_FILE && !obj->soft_del) {
+		if (obj->n_data_chunks <= 0) {
+			/* Empty file with no duplicate object headers,
+			 * just delete it immediately */
+			yaffs_free_tnode(obj->my_dev,
+					 obj->variant.file_variant.top);
+			obj->variant.file_variant.top = NULL;
+			yaffs_trace(YAFFS_TRACE_TRACING,
+				"yaffs: Deleting empty file %d",
+				obj->obj_id);
+			yaffs_generic_obj_del(obj);
+		} else {
+			yaffs_soft_del_worker(obj,
+					      obj->variant.file_variant.top,
+					      obj->variant.
+					      file_variant.top_level, 0);
+			obj->soft_del = 1;
+		}
+	}
+}
+
+/* Pruning removes any part of the file structure tree that is beyond the
+ * bounds of the file (ie that does not point to chunks).
+ *
+ * A file should only get pruned when its size is reduced.
+ *
+ * Before pruning, the chunks must be pulled from the tree and the
+ * level 0 tnode entries must be zeroed out.
+ * Could also use this for file deletion, but that's probably better handled
+ * by a special case.
+ *
+ * This function is recursive. For levels > 0 the function is called again on
+ * any sub-tree. For level == 0 we just check if the sub-tree has data.
+ * If there is no data in a subtree then it is pruned.
+ */
+
+static struct yaffs_tnode *yaffs_prune_worker(struct yaffs_dev *dev,
+					      struct yaffs_tnode *tn, u32 level,
+					      int del0)
+{
+	int i;
+	int has_data;
+
+	if (tn) {
+		has_data = 0;
+
+		if (level > 0) {
+			for (i = 0; i < YAFFS_NTNODES_INTERNAL; i++) {
+				if (tn->internal[i]) {
+					tn->internal[i] =
+					    yaffs_prune_worker(dev,
+							tn->internal[i],
+							level - 1,
+							(i == 0) ? del0 : 1);
+				}
+
+				if (tn->internal[i])
+					has_data++;
+			}
+		} else {
+			int tnode_size_u32 = dev->tnode_size / sizeof(u32);
+			u32 *map = (u32 *) tn;
+
+			for (i = 0; !has_data && i < tnode_size_u32; i++) {
+				if (map[i])
+					has_data++;
+			}
+		}
+
+		if (has_data == 0 && del0) {
+			/* Free and return NULL */
+
+			yaffs_free_tnode(dev, tn);
+			tn = NULL;
+		}
+	}
+	return tn;
+}
+
+static int yaffs_prune_tree(struct yaffs_dev *dev,
+			    struct yaffs_file_var *file_struct)
+{
+	int i;
+	int has_data;
+	int done = 0;
+	struct yaffs_tnode *tn;
+
+	if (file_struct->top_level > 0) {
+		file_struct->top =
+		    yaffs_prune_worker(dev, file_struct->top,
+				       file_struct->top_level, 0);
+
+		/* Now we have a tree with all the non-zero branches NULL but
+		 * the height is the same as it was.
+		 * Let's see if we can trim internal tnodes to shorten the tree.
+		 * We can do this if only the 0th element in the tnode is in use
+		 * (ie all the non-zero are NULL)
+		 */
+
+		while (file_struct->top_level && !done) {
+			tn = file_struct->top;
+
+			has_data = 0;
+			for (i = 1; i < YAFFS_NTNODES_INTERNAL; i++) {
+				if (tn->internal[i])
+					has_data++;
+			}
+
+			if (!has_data) {
+				file_struct->top = tn->internal[0];
+				file_struct->top_level--;
+				yaffs_free_tnode(dev, tn);
+			} else {
+				done = 1;
+			}
+		}
+	}
+	return YAFFS_OK;
+}
+
+/*-------------------- End of File Structure functions.-------------------*/
+
+/* alloc_empty_obj gets us a clean Object.*/
+static struct yaffs_obj *yaffs_alloc_empty_obj(struct yaffs_dev *dev)
+{
+	struct yaffs_obj *obj = yaffs_alloc_raw_obj(dev);
+
+	if (obj) {
+		dev->n_obj++;
+
+		/* Now sweeten it up... */
+
+		memset(obj, 0, sizeof(struct yaffs_obj));
+		obj->being_created = 1;
+
+		obj->my_dev = dev;
+		obj->hdr_chunk = 0;
+		obj->variant_type = YAFFS_OBJECT_TYPE_UNKNOWN;
+		INIT_LIST_HEAD(&(obj->hard_links));
+		INIT_LIST_HEAD(&(obj->hash_link));
+		INIT_LIST_HEAD(&obj->siblings);
+
+		/* Now make the directory sane */
+		if (dev->root_dir) {
+			obj->parent = dev->root_dir;
+			list_add(&(obj->siblings),
+				 &dev->root_dir->variant.dir_variant.children);
+		}
+
+		/* Add it to the lost and found directory.
+		 * NB Can't put root or lost-n-found in lost-n-found so
+		 * check if lost-n-found exists first
+		 */
+		if (dev->lost_n_found)
+			yaffs_add_obj_to_dir(dev->lost_n_found, obj);
+
+		obj->being_created = 0;
+	}
+
+	dev->checkpoint_blocks_required = 0;	/* force recalculation */
+
+	return obj;
+}
+
+static int yaffs_find_nice_bucket(struct yaffs_dev *dev)
+{
+	int i;
+	int l = 999;
+	int lowest = 999999;
+
+	/* Search for the shortest list or one that
+	 * isn't too long.
+	 */
+
+	for (i = 0; i < 10 && lowest > 4; i++) {
+		dev->bucket_finder++;
+		dev->bucket_finder %= YAFFS_NOBJECT_BUCKETS;
+		if (dev->obj_bucket[dev->bucket_finder].count < lowest) {
+			lowest = dev->obj_bucket[dev->bucket_finder].count;
+			l = dev->bucket_finder;
+		}
+	}
+
+	return l;
+}
+
+static int yaffs_new_obj_id(struct yaffs_dev *dev)
+{
+	int bucket = yaffs_find_nice_bucket(dev);
+	int found = 0;
+	struct list_head *i;
+	u32 n = (u32) bucket;
+
+	/* Now find an object value that has not already been taken
+	 * by scanning the list.
+	 */
+
+	while (!found) {
+		found = 1;
+		n += YAFFS_NOBJECT_BUCKETS;
+		if (1 || dev->obj_bucket[bucket].count > 0) {
+			list_for_each(i, &dev->obj_bucket[bucket].list) {
+				/* If there is already one in the list */
+				if (i && list_entry(i, struct yaffs_obj,
+						    hash_link)->obj_id == n) {
+					found = 0;
+				}
+			}
+		}
+	}
+	return n;
+}
+
+static void yaffs_hash_obj(struct yaffs_obj *in)
+{
+	int bucket = yaffs_hash_fn(in->obj_id);
+	struct yaffs_dev *dev = in->my_dev;
+
+	list_add(&in->hash_link, &dev->obj_bucket[bucket].list);
+	dev->obj_bucket[bucket].count++;
+}
+
+struct yaffs_obj *yaffs_find_by_number(struct yaffs_dev *dev, u32 number)
+{
+	int bucket = yaffs_hash_fn(number);
+	struct list_head *i;
+	struct yaffs_obj *in;
+
+	list_for_each(i, &dev->obj_bucket[bucket].list) {
+		/* Look if it is in the list */
+		in = list_entry(i, struct yaffs_obj, hash_link);
+		if (in->obj_id == number) {
+			/* Don't show if it is defered free */
+			if (in->defered_free)
+				return NULL;
+			return in;
+		}
+	}
+
+	return NULL;
+}
+
+struct yaffs_obj *yaffs_new_obj(struct yaffs_dev *dev, int number,
+				enum yaffs_obj_type type)
+{
+	struct yaffs_obj *the_obj = NULL;
+	struct yaffs_tnode *tn = NULL;
+
+	if (number < 0)
+		number = yaffs_new_obj_id(dev);
+
+	if (type == YAFFS_OBJECT_TYPE_FILE) {
+		tn = yaffs_get_tnode(dev);
+		if (!tn)
+			return NULL;
+	}
+
+	the_obj = yaffs_alloc_empty_obj(dev);
+	if (!the_obj) {
+		if (tn)
+			yaffs_free_tnode(dev, tn);
+		return NULL;
+	}
+
+	if (the_obj) {
+		the_obj->fake = 0;
+		the_obj->rename_allowed = 1;
+		the_obj->unlink_allowed = 1;
+		the_obj->obj_id = number;
+		yaffs_hash_obj(the_obj);
+		the_obj->variant_type = type;
+		yaffs_load_current_time(the_obj, 1, 1);
+
+		switch (type) {
+		case YAFFS_OBJECT_TYPE_FILE:
+			the_obj->variant.file_variant.file_size = 0;
+			the_obj->variant.file_variant.scanned_size = 0;
+			the_obj->variant.file_variant.shrink_size = ~0;
+								/* max */
+			the_obj->variant.file_variant.top_level = 0;
+			the_obj->variant.file_variant.top = tn;
+			break;
+		case YAFFS_OBJECT_TYPE_DIRECTORY:
+			INIT_LIST_HEAD(&the_obj->variant.dir_variant.children);
+			INIT_LIST_HEAD(&the_obj->variant.dir_variant.dirty);
+			break;
+		case YAFFS_OBJECT_TYPE_SYMLINK:
+		case YAFFS_OBJECT_TYPE_HARDLINK:
+		case YAFFS_OBJECT_TYPE_SPECIAL:
+			/* No action required */
+			break;
+		case YAFFS_OBJECT_TYPE_UNKNOWN:
+			/* todo this should not happen */
+			break;
+		}
+	}
+
+	return the_obj;
+}
+
+static struct yaffs_obj *yaffs_create_fake_dir(struct yaffs_dev *dev,
+					       int number, u32 mode)
+{
+
+	struct yaffs_obj *obj =
+	    yaffs_new_obj(dev, number, YAFFS_OBJECT_TYPE_DIRECTORY);
+
+	if (obj) {
+		obj->fake = 1;	/* it is fake so it might not use NAND */
+		obj->rename_allowed = 0;
+		obj->unlink_allowed = 0;
+		obj->deleted = 0;
+		obj->unlinked = 0;
+		obj->yst_mode = mode;
+		obj->my_dev = dev;
+		obj->hdr_chunk = 0;	/* Not a valid chunk. */
+	}
+	return obj;
+
+}
+
+
+static void yaffs_init_tnodes_and_objs(struct yaffs_dev *dev)
+{
+	int i;
+
+	dev->n_obj = 0;
+	dev->n_tnodes = 0;
+	yaffs_init_raw_tnodes_and_objs(dev);
+
+	for (i = 0; i < YAFFS_NOBJECT_BUCKETS; i++) {
+		INIT_LIST_HEAD(&dev->obj_bucket[i].list);
+		dev->obj_bucket[i].count = 0;
+	}
+}
+
+struct yaffs_obj *yaffs_find_or_create_by_number(struct yaffs_dev *dev,
+						 int number,
+						 enum yaffs_obj_type type)
+{
+	struct yaffs_obj *the_obj = NULL;
+
+	if (number > 0)
+		the_obj = yaffs_find_by_number(dev, number);
+
+	if (!the_obj)
+		the_obj = yaffs_new_obj(dev, number, type);
+
+	return the_obj;
+
+}
+
+YCHAR *yaffs_clone_str(const YCHAR *str)
+{
+	YCHAR *new_str = NULL;
+	int len;
+
+	if (!str)
+		str = _Y("");
+
+	len = strnlen(str, YAFFS_MAX_ALIAS_LENGTH);
+	new_str = kmalloc((len + 1) * sizeof(YCHAR), GFP_NOFS);
+	if (new_str) {
+		strncpy(new_str, str, len);
+		new_str[len] = 0;
+	}
+	return new_str;
+
+}
+/*
+ *yaffs_update_parent() handles fixing a directories mtime and ctime when a new
+ * link (ie. name) is created or deleted in the directory.
+ *
+ * ie.
+ *   create dir/a : update dir's mtime/ctime
+ *   rm dir/a:   update dir's mtime/ctime
+ *   modify dir/a: don't update dir's mtimme/ctime
+ *
+ * This can be handled immediately or defered. Defering helps reduce the number
+ * of updates when many files in a directory are changed within a brief period.
+ *
+ * If the directory updating is defered then yaffs_update_dirty_dirs must be
+ * called periodically.
+ */
+
+static void yaffs_update_parent(struct yaffs_obj *obj)
+{
+	struct yaffs_dev *dev;
+
+	if (!obj)
+		return;
+	dev = obj->my_dev;
+	obj->dirty = 1;
+	yaffs_load_current_time(obj, 0, 1);
+	if (dev->param.defered_dir_update) {
+		struct list_head *link = &obj->variant.dir_variant.dirty;
+
+		if (list_empty(link)) {
+			list_add(link, &dev->dirty_dirs);
+			yaffs_trace(YAFFS_TRACE_BACKGROUND,
+			  "Added object %d to dirty directories",
+			   obj->obj_id);
+		}
+
+	} else {
+		yaffs_update_oh(obj, NULL, 0, 0, 0, NULL);
+	}
+}
+
+void yaffs_update_dirty_dirs(struct yaffs_dev *dev)
+{
+	struct list_head *link;
+	struct yaffs_obj *obj;
+	struct yaffs_dir_var *d_s;
+	union yaffs_obj_var *o_v;
+
+	yaffs_trace(YAFFS_TRACE_BACKGROUND, "Update dirty directories");
+
+	while (!list_empty(&dev->dirty_dirs)) {
+		link = dev->dirty_dirs.next;
+		list_del_init(link);
+
+		d_s = list_entry(link, struct yaffs_dir_var, dirty);
+		o_v = list_entry(d_s, union yaffs_obj_var, dir_variant);
+		obj = list_entry(o_v, struct yaffs_obj, variant);
+
+		yaffs_trace(YAFFS_TRACE_BACKGROUND, "Update directory %d",
+			obj->obj_id);
+
+		if (obj->dirty)
+			yaffs_update_oh(obj, NULL, 0, 0, 0, NULL);
+	}
+}
+
+/*
+ * Mknod (create) a new object.
+ * equiv_obj only has meaning for a hard link;
+ * alias_str only has meaning for a symlink.
+ * rdev only has meaning for devices (a subset of special objects)
+ */
+
+static struct yaffs_obj *yaffs_create_obj(enum yaffs_obj_type type,
+					  struct yaffs_obj *parent,
+					  const YCHAR *name,
+					  u32 mode,
+					  u32 uid,
+					  u32 gid,
+					  struct yaffs_obj *equiv_obj,
+					  const YCHAR *alias_str, u32 rdev)
+{
+	struct yaffs_obj *in;
+	YCHAR *str = NULL;
+	struct yaffs_dev *dev = parent->my_dev;
+
+	/* Check if the entry exists.
+	 * If it does then fail the call since we don't want a dup. */
+	if (yaffs_find_by_name(parent, name))
+		return NULL;
+
+	if (type == YAFFS_OBJECT_TYPE_SYMLINK) {
+		str = yaffs_clone_str(alias_str);
+		if (!str)
+			return NULL;
+	}
+
+	in = yaffs_new_obj(dev, -1, type);
+
+	if (!in) {
+		kfree(str);
+		return NULL;
+	}
+
+	if (in) {
+		in->hdr_chunk = 0;
+		in->valid = 1;
+		in->variant_type = type;
+
+		in->yst_mode = mode;
+
+		yaffs_attribs_init(in, gid, uid, rdev);
+
+		in->n_data_chunks = 0;
+
+		yaffs_set_obj_name(in, name);
+		in->dirty = 1;
+
+		yaffs_add_obj_to_dir(parent, in);
+
+		in->my_dev = parent->my_dev;
+
+		switch (type) {
+		case YAFFS_OBJECT_TYPE_SYMLINK:
+			in->variant.symlink_variant.alias = str;
+			break;
+		case YAFFS_OBJECT_TYPE_HARDLINK:
+			in->variant.hardlink_variant.equiv_obj = equiv_obj;
+			in->variant.hardlink_variant.equiv_id =
+			    equiv_obj->obj_id;
+			list_add(&in->hard_links, &equiv_obj->hard_links);
+			break;
+		case YAFFS_OBJECT_TYPE_FILE:
+		case YAFFS_OBJECT_TYPE_DIRECTORY:
+		case YAFFS_OBJECT_TYPE_SPECIAL:
+		case YAFFS_OBJECT_TYPE_UNKNOWN:
+			/* do nothing */
+			break;
+		}
+
+		if (yaffs_update_oh(in, name, 0, 0, 0, NULL) < 0) {
+			/* Could not create the object header, fail */
+			yaffs_del_obj(in);
+			in = NULL;
+		}
+
+		yaffs_update_parent(parent);
+	}
+
+	return in;
+}
+
+struct yaffs_obj *yaffs_create_file(struct yaffs_obj *parent,
+				    const YCHAR *name, u32 mode, u32 uid,
+				    u32 gid)
+{
+	return yaffs_create_obj(YAFFS_OBJECT_TYPE_FILE, parent, name, mode,
+				uid, gid, NULL, NULL, 0);
+}
+
+struct yaffs_obj *yaffs_create_dir(struct yaffs_obj *parent, const YCHAR *name,
+				   u32 mode, u32 uid, u32 gid)
+{
+	return yaffs_create_obj(YAFFS_OBJECT_TYPE_DIRECTORY, parent, name,
+				mode, uid, gid, NULL, NULL, 0);
+}
+
+struct yaffs_obj *yaffs_create_special(struct yaffs_obj *parent,
+				       const YCHAR *name, u32 mode, u32 uid,
+				       u32 gid, u32 rdev)
+{
+	return yaffs_create_obj(YAFFS_OBJECT_TYPE_SPECIAL, parent, name, mode,
+				uid, gid, NULL, NULL, rdev);
+}
+
+struct yaffs_obj *yaffs_create_symlink(struct yaffs_obj *parent,
+				       const YCHAR *name, u32 mode, u32 uid,
+				       u32 gid, const YCHAR *alias)
+{
+	return yaffs_create_obj(YAFFS_OBJECT_TYPE_SYMLINK, parent, name, mode,
+				uid, gid, NULL, alias, 0);
+}
+
+/* yaffs_link_obj returns the object id of the equivalent object.*/
+struct yaffs_obj *yaffs_link_obj(struct yaffs_obj *parent, const YCHAR * name,
+				 struct yaffs_obj *equiv_obj)
+{
+	/* Get the real object in case we were fed a hard link obj */
+	equiv_obj = yaffs_get_equivalent_obj(equiv_obj);
+
+	if (yaffs_create_obj
+	    (YAFFS_OBJECT_TYPE_HARDLINK, parent, name, 0, 0, 0,
+	     equiv_obj, NULL, 0))
+		return equiv_obj;
+	else
+		return NULL;
+
+}
+
+
+
+/*---------------------- Block Management and Page Allocation -------------*/
+
+static int yaffs_init_blocks(struct yaffs_dev *dev)
+{
+	int n_blocks = dev->internal_end_block - dev->internal_start_block + 1;
+
+	dev->block_info = NULL;
+	dev->chunk_bits = NULL;
+	dev->alloc_block = -1;	/* force it to get a new one */
+
+	/* If the first allocation strategy fails, thry the alternate one */
+	dev->block_info =
+		kmalloc(n_blocks * sizeof(struct yaffs_block_info), GFP_NOFS);
+	if (!dev->block_info) {
+		dev->block_info =
+		    vmalloc(n_blocks * sizeof(struct yaffs_block_info));
+		dev->block_info_alt = 1;
+	} else {
+		dev->block_info_alt = 0;
+	}
+
+	if (dev->block_info) {
+		/* Set up dynamic blockinfo stuff. Round up bytes. */
+		dev->chunk_bit_stride = (dev->param.chunks_per_block + 7) / 8;
+		dev->chunk_bits =
+			kmalloc(dev->chunk_bit_stride * n_blocks, GFP_NOFS);
+		if (!dev->chunk_bits) {
+			dev->chunk_bits =
+			    vmalloc(dev->chunk_bit_stride * n_blocks);
+			dev->chunk_bits_alt = 1;
+		} else {
+			dev->chunk_bits_alt = 0;
+		}
+	}
+
+	if (dev->block_info && dev->chunk_bits) {
+		memset(dev->block_info, 0,
+		       n_blocks * sizeof(struct yaffs_block_info));
+		memset(dev->chunk_bits, 0, dev->chunk_bit_stride * n_blocks);
+		return YAFFS_OK;
+	}
+
+	return YAFFS_FAIL;
+}
+
+static void yaffs_deinit_blocks(struct yaffs_dev *dev)
+{
+	if (dev->block_info_alt && dev->block_info)
+		vfree(dev->block_info);
+	else
+		kfree(dev->block_info);
+
+	dev->block_info_alt = 0;
+
+	dev->block_info = NULL;
+
+	if (dev->chunk_bits_alt && dev->chunk_bits)
+		vfree(dev->chunk_bits);
+	else
+		kfree(dev->chunk_bits);
+	dev->chunk_bits_alt = 0;
+	dev->chunk_bits = NULL;
+}
+
+void yaffs_block_became_dirty(struct yaffs_dev *dev, int block_no)
+{
+	struct yaffs_block_info *bi = yaffs_get_block_info(dev, block_no);
+	int erased_ok = 0;
+
+	/* If the block is still healthy erase it and mark as clean.
+	 * If the block has had a data failure, then retire it.
+	 */
+
+	yaffs_trace(YAFFS_TRACE_GC | YAFFS_TRACE_ERASE,
+		"yaffs_block_became_dirty block %d state %d %s",
+		block_no, bi->block_state,
+		(bi->needs_retiring) ? "needs retiring" : "");
+
+	yaffs2_clear_oldest_dirty_seq(dev, bi);
+
+	bi->block_state = YAFFS_BLOCK_STATE_DIRTY;
+
+	/* If this is the block being garbage collected then stop gc'ing */
+	if (block_no == dev->gc_block)
+		dev->gc_block = 0;
+
+	/* If this block is currently the best candidate for gc
+	 * then drop as a candidate */
+	if (block_no == dev->gc_dirtiest) {
+		dev->gc_dirtiest = 0;
+		dev->gc_pages_in_use = 0;
+	}
+
+	if (!bi->needs_retiring) {
+		yaffs2_checkpt_invalidate(dev);
+		erased_ok = yaffs_erase_block(dev, block_no);
+		if (!erased_ok) {
+			dev->n_erase_failures++;
+			yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
+			  "**>> Erasure failed %d", block_no);
+		}
+	}
+
+	if (erased_ok &&
+	    ((yaffs_trace_mask & YAFFS_TRACE_ERASE)
+	     || !yaffs_skip_verification(dev))) {
+		int i;
+		for (i = 0; i < dev->param.chunks_per_block; i++) {
+			if (!yaffs_check_chunk_erased
+			    (dev, block_no * dev->param.chunks_per_block + i)) {
+				yaffs_trace(YAFFS_TRACE_ERROR,
+					">>Block %d erasure supposedly OK, but chunk %d not erased",
+					block_no, i);
+			}
+		}
+	}
+
+	if (erased_ok) {
+		/* Clean it up... */
+		bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
+		bi->seq_number = 0;
+		dev->n_erased_blocks++;
+		bi->pages_in_use = 0;
+		bi->soft_del_pages = 0;
+		bi->has_shrink_hdr = 0;
+		bi->skip_erased_check = 1;	/* Clean, so no need to check */
+		bi->gc_prioritise = 0;
+		yaffs_clear_chunk_bits(dev, block_no);
+
+		yaffs_trace(YAFFS_TRACE_ERASE,
+			"Erased block %d", block_no);
+	} else {
+		/* We lost a block of free space */
+		dev->n_free_chunks -= dev->param.chunks_per_block;
+		yaffs_retire_block(dev, block_no);
+		yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
+			"**>> Block %d retired", block_no);
+	}
+}
+
+static int yaffs_gc_process_chunk(struct yaffs_dev *dev,
+				struct yaffs_block_info *bi,
+				int old_chunk, u8 *buffer)
+{
+	int new_chunk;
+	int mark_flash = 1;
+	struct yaffs_ext_tags tags;
+	struct yaffs_obj *object;
+	int matching_chunk;
+	int ret_val = YAFFS_OK;
+
+	yaffs_init_tags(&tags);
+	yaffs_rd_chunk_tags_nand(dev, old_chunk,
+				 buffer, &tags);
+	object = yaffs_find_by_number(dev, tags.obj_id);
+
+	yaffs_trace(YAFFS_TRACE_GC_DETAIL,
+		"Collecting chunk in block %d, %d %d %d ",
+		dev->gc_chunk, tags.obj_id,
+		tags.chunk_id, tags.n_bytes);
+
+	if (object && !yaffs_skip_verification(dev)) {
+		if (tags.chunk_id == 0)
+			matching_chunk =
+			    object->hdr_chunk;
+		else if (object->soft_del)
+			/* Defeat the test */
+			matching_chunk = old_chunk;
+		else
+			matching_chunk =
+			    yaffs_find_chunk_in_file
+			    (object, tags.chunk_id,
+			     NULL);
+
+		if (old_chunk != matching_chunk)
+			yaffs_trace(YAFFS_TRACE_ERROR,
+				"gc: page in gc mismatch: %d %d %d %d",
+				old_chunk,
+				matching_chunk,
+				tags.obj_id,
+				tags.chunk_id);
+	}
+
+	if (!object) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+			"page %d in gc has no object: %d %d %d ",
+			old_chunk,
+			tags.obj_id, tags.chunk_id,
+			tags.n_bytes);
+	}
+
+	if (object &&
+	    object->deleted &&
+	    object->soft_del && tags.chunk_id != 0) {
+		/* Data chunk in a soft deleted file,
+		 * throw it away.
+		 * It's a soft deleted data chunk,
+		 * No need to copy this, just forget
+		 * about it and fix up the object.
+		 */
+
+		/* Free chunks already includes
+		 * softdeleted chunks, how ever this
+		 * chunk is going to soon be really
+		 * deleted which will increment free
+		 * chunks. We have to decrement free
+		 * chunks so this works out properly.
+		 */
+		dev->n_free_chunks--;
+		bi->soft_del_pages--;
+
+		object->n_data_chunks--;
+		if (object->n_data_chunks <= 0) {
+			/* remeber to clean up obj */
+			dev->gc_cleanup_list[dev->n_clean_ups] = tags.obj_id;
+			dev->n_clean_ups++;
+		}
+		mark_flash = 0;
+	} else if (object) {
+		/* It's either a data chunk in a live
+		 * file or an ObjectHeader, so we're
+		 * interested in it.
+		 * NB Need to keep the ObjectHeaders of
+		 * deleted files until the whole file
+		 * has been deleted off
+		 */
+		tags.serial_number++;
+		dev->n_gc_copies++;
+
+		if (tags.chunk_id == 0) {
+			/* It is an object Id,
+			 * We need to nuke the
+			 * shrinkheader flags since its
+			 * work is done.
+			 * Also need to clean up
+			 * shadowing.
+			 */
+			struct yaffs_obj_hdr *oh;
+			oh = (struct yaffs_obj_hdr *) buffer;
+
+			oh->is_shrink = 0;
+			tags.extra_is_shrink = 0;
+			oh->shadows_obj = 0;
+			oh->inband_shadowed_obj_id = 0;
+			tags.extra_shadows = 0;
+
+			/* Update file size */
+			if (object->variant_type == YAFFS_OBJECT_TYPE_FILE) {
+				oh->file_size =
+				    object->variant.file_variant.file_size;
+				tags.extra_length = oh->file_size;
+			}
+
+			yaffs_verify_oh(object, oh, &tags, 1);
+			new_chunk =
+			    yaffs_write_new_chunk(dev, (u8 *) oh, &tags, 1);
+		} else {
+			new_chunk =
+			    yaffs_write_new_chunk(dev, buffer, &tags, 1);
+		}
+
+		if (new_chunk < 0) {
+			ret_val = YAFFS_FAIL;
+		} else {
+
+			/* Now fix up the Tnodes etc. */
+
+			if (tags.chunk_id == 0) {
+				/* It's a header */
+				object->hdr_chunk = new_chunk;
+				object->serial = tags.serial_number;
+			} else {
+				/* It's a data chunk */
+				yaffs_put_chunk_in_file(object, tags.chunk_id,
+							new_chunk, 0);
+			}
+		}
+	}
+	if (ret_val == YAFFS_OK)
+		yaffs_chunk_del(dev, old_chunk, mark_flash, __LINE__);
+	return ret_val;
+}
+
+static int yaffs_gc_block(struct yaffs_dev *dev, int block, int whole_block)
+{
+	int old_chunk;
+	int ret_val = YAFFS_OK;
+	int i;
+	int is_checkpt_block;
+	int max_copies;
+	int chunks_before = yaffs_get_erased_chunks(dev);
+	int chunks_after;
+	struct yaffs_block_info *bi = yaffs_get_block_info(dev, block);
+
+	is_checkpt_block = (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT);
+
+	yaffs_trace(YAFFS_TRACE_TRACING,
+		"Collecting block %d, in use %d, shrink %d, whole_block %d",
+		block, bi->pages_in_use, bi->has_shrink_hdr,
+		whole_block);
+
+	/*yaffs_verify_free_chunks(dev); */
+
+	if (bi->block_state == YAFFS_BLOCK_STATE_FULL)
+		bi->block_state = YAFFS_BLOCK_STATE_COLLECTING;
+
+	bi->has_shrink_hdr = 0;	/* clear the flag so that the block can erase */
+
+	dev->gc_disable = 1;
+
+	if (is_checkpt_block || !yaffs_still_some_chunks(dev, block)) {
+		yaffs_trace(YAFFS_TRACE_TRACING,
+			"Collecting block %d that has no chunks in use",
+			block);
+		yaffs_block_became_dirty(dev, block);
+	} else {
+
+		u8 *buffer = yaffs_get_temp_buffer(dev, __LINE__);
+
+		yaffs_verify_blk(dev, bi, block);
+
+		max_copies = (whole_block) ? dev->param.chunks_per_block : 5;
+		old_chunk = block * dev->param.chunks_per_block + dev->gc_chunk;
+
+		for (/* init already done */ ;
+		     ret_val == YAFFS_OK &&
+		     dev->gc_chunk < dev->param.chunks_per_block &&
+		     (bi->block_state == YAFFS_BLOCK_STATE_COLLECTING) &&
+		     max_copies > 0;
+		     dev->gc_chunk++, old_chunk++) {
+			if (yaffs_check_chunk_bit(dev, block, dev->gc_chunk)) {
+				/* Page is in use and might need to be copied */
+				max_copies--;
+				ret_val = yaffs_gc_process_chunk(dev, bi,
+							old_chunk, buffer);
+			}
+		}
+		yaffs_release_temp_buffer(dev, buffer, __LINE__);
+	}
+
+	yaffs_verify_collected_blk(dev, bi, block);
+
+	if (bi->block_state == YAFFS_BLOCK_STATE_COLLECTING) {
+		/*
+		 * The gc did not complete. Set block state back to FULL
+		 * because checkpointing does not restore gc.
+		 */
+		bi->block_state = YAFFS_BLOCK_STATE_FULL;
+	} else {
+		/* The gc completed. */
+		/* Do any required cleanups */
+		for (i = 0; i < dev->n_clean_ups; i++) {
+			/* Time to delete the file too */
+			struct yaffs_obj *object =
+			    yaffs_find_by_number(dev, dev->gc_cleanup_list[i]);
+			if (object) {
+				yaffs_free_tnode(dev,
+					  object->variant.file_variant.top);
+				object->variant.file_variant.top = NULL;
+				yaffs_trace(YAFFS_TRACE_GC,
+					"yaffs: About to finally delete object %d",
+					object->obj_id);
+				yaffs_generic_obj_del(object);
+				object->my_dev->n_deleted_files--;
+			}
+
+		}
+		chunks_after = yaffs_get_erased_chunks(dev);
+		if (chunks_before >= chunks_after)
+			yaffs_trace(YAFFS_TRACE_GC,
+				"gc did not increase free chunks before %d after %d",
+				chunks_before, chunks_after);
+		dev->gc_block = 0;
+		dev->gc_chunk = 0;
+		dev->n_clean_ups = 0;
+	}
+
+	dev->gc_disable = 0;
+
+	return ret_val;
+}
+
+/*
+ * find_gc_block() selects the dirtiest block (or close enough)
+ * for garbage collection.
+ */
+
+static unsigned yaffs_find_gc_block(struct yaffs_dev *dev,
+				    int aggressive, int background)
+{
+	int i;
+	int iterations;
+	unsigned selected = 0;
+	int prioritised = 0;
+	int prioritised_exist = 0;
+	struct yaffs_block_info *bi;
+	int threshold;
+
+	/* First let's see if we need to grab a prioritised block */
+	if (dev->has_pending_prioritised_gc && !aggressive) {
+		dev->gc_dirtiest = 0;
+		bi = dev->block_info;
+		for (i = dev->internal_start_block;
+		     i <= dev->internal_end_block && !selected; i++) {
+
+			if (bi->gc_prioritise) {
+				prioritised_exist = 1;
+				if (bi->block_state == YAFFS_BLOCK_STATE_FULL &&
+				    yaffs_block_ok_for_gc(dev, bi)) {
+					selected = i;
+					prioritised = 1;
+				}
+			}
+			bi++;
+		}
+
+		/*
+		 * If there is a prioritised block and none was selected then
+		 * this happened because there is at least one old dirty block
+		 * gumming up the works. Let's gc the oldest dirty block.
+		 */
+
+		if (prioritised_exist &&
+		    !selected && dev->oldest_dirty_block > 0)
+			selected = dev->oldest_dirty_block;
+
+		if (!prioritised_exist)	/* None found, so we can clear this */
+			dev->has_pending_prioritised_gc = 0;
+	}
+
+	/* If we're doing aggressive GC then we are happy to take a less-dirty
+	 * block, and search harder.
+	 * else (leasurely gc), then we only bother to do this if the
+	 * block has only a few pages in use.
+	 */
+
+	if (!selected) {
+		int pages_used;
+		int n_blocks =
+		    dev->internal_end_block - dev->internal_start_block + 1;
+		if (aggressive) {
+			threshold = dev->param.chunks_per_block;
+			iterations = n_blocks;
+		} else {
+			int max_threshold;
+
+			if (background)
+				max_threshold = dev->param.chunks_per_block / 2;
+			else
+				max_threshold = dev->param.chunks_per_block / 8;
+
+			if (max_threshold < YAFFS_GC_PASSIVE_THRESHOLD)
+				max_threshold = YAFFS_GC_PASSIVE_THRESHOLD;
+
+			threshold = background ? (dev->gc_not_done + 2) * 2 : 0;
+			if (threshold < YAFFS_GC_PASSIVE_THRESHOLD)
+				threshold = YAFFS_GC_PASSIVE_THRESHOLD;
+			if (threshold > max_threshold)
+				threshold = max_threshold;
+
+			iterations = n_blocks / 16 + 1;
+			if (iterations > 100)
+				iterations = 100;
+		}
+
+		for (i = 0;
+		     i < iterations &&
+		     (dev->gc_dirtiest < 1 ||
+		      dev->gc_pages_in_use > YAFFS_GC_GOOD_ENOUGH);
+		     i++) {
+			dev->gc_block_finder++;
+			if (dev->gc_block_finder < dev->internal_start_block ||
+			    dev->gc_block_finder > dev->internal_end_block)
+				dev->gc_block_finder =
+				    dev->internal_start_block;
+
+			bi = yaffs_get_block_info(dev, dev->gc_block_finder);
+
+			pages_used = bi->pages_in_use - bi->soft_del_pages;
+
+			if (bi->block_state == YAFFS_BLOCK_STATE_FULL &&
+			    pages_used < dev->param.chunks_per_block &&
+			    (dev->gc_dirtiest < 1 ||
+			     pages_used < dev->gc_pages_in_use) &&
+			    yaffs_block_ok_for_gc(dev, bi)) {
+				dev->gc_dirtiest = dev->gc_block_finder;
+				dev->gc_pages_in_use = pages_used;
+			}
+		}
+
+		if (dev->gc_dirtiest > 0 && dev->gc_pages_in_use <= threshold)
+			selected = dev->gc_dirtiest;
+	}
+
+	/*
+	 * If nothing has been selected for a while, try the oldest dirty
+	 * because that's gumming up the works.
+	 */
+
+	if (!selected && dev->param.is_yaffs2 &&
+	    dev->gc_not_done >= (background ? 10 : 20)) {
+		yaffs2_find_oldest_dirty_seq(dev);
+		if (dev->oldest_dirty_block > 0) {
+			selected = dev->oldest_dirty_block;
+			dev->gc_dirtiest = selected;
+			dev->oldest_dirty_gc_count++;
+			bi = yaffs_get_block_info(dev, selected);
+			dev->gc_pages_in_use =
+			    bi->pages_in_use - bi->soft_del_pages;
+		} else {
+			dev->gc_not_done = 0;
+		}
+	}
+
+	if (selected) {
+		yaffs_trace(YAFFS_TRACE_GC,
+			"GC Selected block %d with %d free, prioritised:%d",
+			selected,
+			dev->param.chunks_per_block - dev->gc_pages_in_use,
+			prioritised);
+
+		dev->n_gc_blocks++;
+		if (background)
+			dev->bg_gcs++;
+
+		dev->gc_dirtiest = 0;
+		dev->gc_pages_in_use = 0;
+		dev->gc_not_done = 0;
+		if (dev->refresh_skip > 0)
+			dev->refresh_skip--;
+	} else {
+		dev->gc_not_done++;
+		yaffs_trace(YAFFS_TRACE_GC,
+			"GC none: finder %d skip %d threshold %d dirtiest %d using %d oldest %d%s",
+			dev->gc_block_finder, dev->gc_not_done, threshold,
+			dev->gc_dirtiest, dev->gc_pages_in_use,
+			dev->oldest_dirty_block, background ? " bg" : "");
+	}
+
+	return selected;
+}
+
+/* New garbage collector
+ * If we're very low on erased blocks then we do aggressive garbage collection
+ * otherwise we do "leasurely" garbage collection.
+ * Aggressive gc looks further (whole array) and will accept less dirty blocks.
+ * Passive gc only inspects smaller areas and only accepts more dirty blocks.
+ *
+ * The idea is to help clear out space in a more spread-out manner.
+ * Dunno if it really does anything useful.
+ */
+static int yaffs_check_gc(struct yaffs_dev *dev, int background)
+{
+	int aggressive = 0;
+	int gc_ok = YAFFS_OK;
+	int max_tries = 0;
+	int min_erased;
+	int erased_chunks;
+	int checkpt_block_adjust;
+
+	if (dev->param.gc_control && (dev->param.gc_control(dev) & 1) == 0)
+		return YAFFS_OK;
+
+	if (dev->gc_disable) {
+		/* Bail out so we don't get recursive gc */
+		return YAFFS_OK;
+	}
+
+	/* This loop should pass the first time.
+	 * Only loops here if the collection does not increase space.
+	 */
+
+	do {
+		max_tries++;
+
+		checkpt_block_adjust = yaffs_calc_checkpt_blocks_required(dev);
+
+		min_erased =
+		    dev->param.n_reserved_blocks + checkpt_block_adjust + 1;
+		erased_chunks =
+		    dev->n_erased_blocks * dev->param.chunks_per_block;
+
+		/* If we need a block soon then do aggressive gc. */
+		if (dev->n_erased_blocks < min_erased)
+			aggressive = 1;
+		else {
+			if (!background
+			    && erased_chunks > (dev->n_free_chunks / 4))
+				break;
+
+			if (dev->gc_skip > 20)
+				dev->gc_skip = 20;
+			if (erased_chunks < dev->n_free_chunks / 2 ||
+			    dev->gc_skip < 1 || background)
+				aggressive = 0;
+			else {
+				dev->gc_skip--;
+				break;
+			}
+		}
+
+		dev->gc_skip = 5;
+
+		/* If we don't already have a block being gc'd then see if we
+		 * should start another */
+
+		if (dev->gc_block < 1 && !aggressive) {
+			dev->gc_block = yaffs2_find_refresh_block(dev);
+			dev->gc_chunk = 0;
+			dev->n_clean_ups = 0;
+		}
+		if (dev->gc_block < 1) {
+			dev->gc_block =
+			    yaffs_find_gc_block(dev, aggressive, background);
+			dev->gc_chunk = 0;
+			dev->n_clean_ups = 0;
+		}
+
+		if (dev->gc_block > 0) {
+			dev->all_gcs++;
+			if (!aggressive)
+				dev->passive_gc_count++;
+
+			yaffs_trace(YAFFS_TRACE_GC,
+				"yaffs: GC n_erased_blocks %d aggressive %d",
+				dev->n_erased_blocks, aggressive);
+
+			gc_ok = yaffs_gc_block(dev, dev->gc_block, aggressive);
+		}
+
+		if (dev->n_erased_blocks < (dev->param.n_reserved_blocks)
+		    && dev->gc_block > 0) {
+			yaffs_trace(YAFFS_TRACE_GC,
+				"yaffs: GC !!!no reclaim!!! n_erased_blocks %d after try %d block %d",
+				dev->n_erased_blocks, max_tries,
+				dev->gc_block);
+		}
+	} while ((dev->n_erased_blocks < dev->param.n_reserved_blocks) &&
+		 (dev->gc_block > 0) && (max_tries < 2));
+
+	return aggressive ? gc_ok : YAFFS_OK;
+}
+
+/*
+ * yaffs_bg_gc()
+ * Garbage collects. Intended to be called from a background thread.
+ * Returns non-zero if at least half the free chunks are erased.
+ */
+int yaffs_bg_gc(struct yaffs_dev *dev, unsigned urgency)
+{
+	int erased_chunks = dev->n_erased_blocks * dev->param.chunks_per_block;
+
+	yaffs_trace(YAFFS_TRACE_BACKGROUND, "Background gc %u", urgency);
+
+	yaffs_check_gc(dev, 1);
+	return erased_chunks > dev->n_free_chunks / 2;
+}
+
+/*-------------------- Data file manipulation -----------------*/
+
+static int yaffs_rd_data_obj(struct yaffs_obj *in, int inode_chunk, u8 * buffer)
+{
+	int nand_chunk = yaffs_find_chunk_in_file(in, inode_chunk, NULL);
+
+	if (nand_chunk >= 0)
+		return yaffs_rd_chunk_tags_nand(in->my_dev, nand_chunk,
+						buffer, NULL);
+	else {
+		yaffs_trace(YAFFS_TRACE_NANDACCESS,
+			"Chunk %d not found zero instead",
+			nand_chunk);
+		/* get sane (zero) data if you read a hole */
+		memset(buffer, 0, in->my_dev->data_bytes_per_chunk);
+		return 0;
+	}
+
+}
+
+void yaffs_chunk_del(struct yaffs_dev *dev, int chunk_id, int mark_flash,
+		     int lyn)
+{
+	int block;
+	int page;
+	struct yaffs_ext_tags tags;
+	struct yaffs_block_info *bi;
+
+	if (chunk_id <= 0)
+		return;
+
+	dev->n_deletions++;
+	block = chunk_id / dev->param.chunks_per_block;
+	page = chunk_id % dev->param.chunks_per_block;
+
+	if (!yaffs_check_chunk_bit(dev, block, page))
+		yaffs_trace(YAFFS_TRACE_VERIFY,
+			"Deleting invalid chunk %d", chunk_id);
+
+	bi = yaffs_get_block_info(dev, block);
+
+	yaffs2_update_oldest_dirty_seq(dev, block, bi);
+
+	yaffs_trace(YAFFS_TRACE_DELETION,
+		"line %d delete of chunk %d",
+		lyn, chunk_id);
+
+	if (!dev->param.is_yaffs2 && mark_flash &&
+	    bi->block_state != YAFFS_BLOCK_STATE_COLLECTING) {
+
+		yaffs_init_tags(&tags);
+		tags.is_deleted = 1;
+		yaffs_wr_chunk_tags_nand(dev, chunk_id, NULL, &tags);
+		yaffs_handle_chunk_update(dev, chunk_id, &tags);
+	} else {
+		dev->n_unmarked_deletions++;
+	}
+
+	/* Pull out of the management area.
+	 * If the whole block became dirty, this will kick off an erasure.
+	 */
+	if (bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING ||
+	    bi->block_state == YAFFS_BLOCK_STATE_FULL ||
+	    bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCANNING ||
+	    bi->block_state == YAFFS_BLOCK_STATE_COLLECTING) {
+		dev->n_free_chunks++;
+		yaffs_clear_chunk_bit(dev, block, page);
+		bi->pages_in_use--;
+
+		if (bi->pages_in_use == 0 &&
+		    !bi->has_shrink_hdr &&
+		    bi->block_state != YAFFS_BLOCK_STATE_ALLOCATING &&
+		    bi->block_state != YAFFS_BLOCK_STATE_NEEDS_SCANNING) {
+			yaffs_block_became_dirty(dev, block);
+		}
+	}
+}
+
+static int yaffs_wr_data_obj(struct yaffs_obj *in, int inode_chunk,
+			     const u8 *buffer, int n_bytes, int use_reserve)
+{
+	/* Find old chunk Need to do this to get serial number
+	 * Write new one and patch into tree.
+	 * Invalidate old tags.
+	 */
+
+	int prev_chunk_id;
+	struct yaffs_ext_tags prev_tags;
+	int new_chunk_id;
+	struct yaffs_ext_tags new_tags;
+	struct yaffs_dev *dev = in->my_dev;
+
+	yaffs_check_gc(dev, 0);
+
+	/* Get the previous chunk at this location in the file if it exists.
+	 * If it does not exist then put a zero into the tree. This creates
+	 * the tnode now, rather than later when it is harder to clean up.
+	 */
+	prev_chunk_id = yaffs_find_chunk_in_file(in, inode_chunk, &prev_tags);
+	if (prev_chunk_id < 1 &&
+	    !yaffs_put_chunk_in_file(in, inode_chunk, 0, 0))
+		return 0;
+
+	/* Set up new tags */
+	yaffs_init_tags(&new_tags);
+
+	new_tags.chunk_id = inode_chunk;
+	new_tags.obj_id = in->obj_id;
+	new_tags.serial_number =
+	    (prev_chunk_id > 0) ? prev_tags.serial_number + 1 : 1;
+	new_tags.n_bytes = n_bytes;
+
+	if (n_bytes < 1 || n_bytes > dev->param.total_bytes_per_chunk) {
+		yaffs_trace(YAFFS_TRACE_ERROR,
+		  "Writing %d bytes to chunk!!!!!!!!!",
+		   n_bytes);
+		YBUG();
+	}
+
+	new_chunk_id =
+	    yaffs_write_new_chunk(dev, buffer, &new_tags, use_reserve);
+
+	if (new_chunk_id > 0) {
+		yaffs_put_chunk_in_file(in, inode_chunk, new_chunk_id, 0);
+
+		if (prev_chunk_id > 0)
+			yaffs_chunk_del(dev, prev_chunk_id, 1, __LINE__);
+
+		yaffs_verify_file_sane(in);
+	}
+	return new_chunk_id;
+
+}
+
+
+
+static int yaffs_do_xattrib_mod(struct yaffs_obj *obj, int set,
+				const YCHAR *name, const void *value, int size,
+				int flags)
+{
+	struct yaffs_xattr_mod xmod;
+	int result;
+
+	xmod.set = set;
+	xmod.name = name;
+	xmod.data = value;
+	xmod.size = size;
+	xmod.flags = flags;
+	xmod.result = -ENOSPC;
+
+	result = yaffs_update_oh(obj, NULL, 0, 0, 0, &xmod);
+
+	if (result > 0)
+		return xmod.result;
+	else
+		return -ENOSPC;
+}
+
+static int yaffs_apply_xattrib_mod(struct yaffs_obj *obj, char *buffer,
+				   struct yaffs_xattr_mod *xmod)
+{
+	int retval = 0;
+	int x_offs = sizeof(struct yaffs_obj_hdr);
+	struct yaffs_dev *dev = obj->my_dev;
+	int x_size = dev->data_bytes_per_chunk - sizeof(struct yaffs_obj_hdr);
+	char *x_buffer = buffer + x_offs;
+
+	if (xmod->set)
+		retval =
+		    nval_set(x_buffer, x_size, xmod->name, xmod->data,
+			     xmod->size, xmod->flags);
+	else
+		retval = nval_del(x_buffer, x_size, xmod->name);
+
+	obj->has_xattr = nval_hasvalues(x_buffer, x_size);
+	obj->xattr_known = 1;
+	xmod->result = retval;
+
+	return retval;
+}
+
+static int yaffs_do_xattrib_fetch(struct yaffs_obj *obj, const YCHAR *name,
+				  void *value, int size)
+{
+	char *buffer = NULL;
+	int result;
+	struct yaffs_ext_tags tags;
+	struct yaffs_dev *dev = obj->my_dev;
+	int x_offs = sizeof(struct yaffs_obj_hdr);
+	int x_size = dev->data_bytes_per_chunk - sizeof(struct yaffs_obj_hdr);
+	char *x_buffer;
+	int retval = 0;
+
+	if (obj->hdr_chunk < 1)
+		return -ENODATA;
+
+	/* If we know that the object has no xattribs then don't do all the
+	 * reading and parsing.
+	 */
+	if (obj->xattr_known && !obj->has_xattr) {
+		if (name)
+			return -ENODATA;
+		else
+			return 0;
+	}
+
+	buffer = (char *)yaffs_get_temp_buffer(dev, __LINE__);
+	if (!buffer)
+		return -ENOMEM;
+
+	result =
+	    yaffs_rd_chunk_tags_nand(dev, obj->hdr_chunk, (u8 *) buffer, &tags);
+
+	if (result != YAFFS_OK)
+		retval = -ENOENT;
+	else {
+		x_buffer = buffer + x_offs;
+
+		if (!obj->xattr_known) {
+			obj->has_xattr = nval_hasvalues(x_buffer, x_size);
+			obj->xattr_known = 1;
+		}
+
+		if (name)
+			retval = nval_get(x_buffer, x_size, name, value, size);
+		else
+			retval = nval_list(x_buffer, x_size, value, size);
+	}
+	yaffs_release_temp_buffer(dev, (u8 *) buffer, __LINE__);
+	return retval;
+}
+
+int yaffs_set_xattrib(struct yaffs_obj *obj, const YCHAR * name,
+		      const void *value, int size, int flags)
+{
+	return yaffs_do_xattrib_mod(obj, 1, name, value, size, flags);
+}
+
+int yaffs_remove_xattrib(struct yaffs_obj *obj, const YCHAR * name)
+{
+	return yaffs_do_xattrib_mod(obj, 0, name, NULL, 0, 0);
+}
+
+int yaffs_get_xattrib(struct yaffs_obj *obj, const YCHAR * name, void *value,
+		      int size)
+{
+	return yaffs_do_xattrib_fetch(obj, name, value, size);
+}
+
+int yaffs_list_xattrib(struct yaffs_obj *obj, char *buffer, int size)
+{
+	return yaffs_do_xattrib_fetch(obj, NULL, buffer, size);
+}
+
+static void yaffs_check_obj_details_loaded(struct yaffs_obj *in)
+{
+	u8 *chunk_data;
+	struct yaffs_obj_hdr *oh;
+	struct yaffs_dev *dev;
+	struct yaffs_ext_tags tags;
+	int result;
+	int alloc_failed = 0;
+
+	if (!in)
+		return;
+
+	dev = in->my_dev;
+
+	if (in->lazy_loaded && in->hdr_chunk > 0) {
+		in->lazy_loaded = 0;
+		chunk_data = yaffs_get_temp_buffer(dev, __LINE__);
+
+		result =
+		    yaffs_rd_chunk_tags_nand(dev, in->hdr_chunk, chunk_data,
+					     &tags);
+		oh = (struct yaffs_obj_hdr *)chunk_data;
+
+		in->yst_mode = oh->yst_mode;
+		yaffs_load_attribs(in, oh);
+		yaffs_set_obj_name_from_oh(in, oh);
+
+		if (in->variant_type == YAFFS_OBJECT_TYPE_SYMLINK) {
+			in->variant.symlink_variant.alias =
+			    yaffs_clone_str(oh->alias);
+			if (!in->variant.symlink_variant.alias)
+				alloc_failed = 1;	/* Not returned */
+		}
+
+		yaffs_release_temp_buffer(dev, chunk_data, __LINE__);
+	}
+}
+
+static void yaffs_load_name_from_oh(struct yaffs_dev *dev, YCHAR *name,
+				    const YCHAR *oh_name, int buff_size)
+{
+#ifdef CONFIG_YAFFS_AUTO_UNICODE
+	if (dev->param.auto_unicode) {
+		if (*oh_name) {
+			/* It is an ASCII name, do an ASCII to
+			 * unicode conversion */
+			const char *ascii_oh_name = (const char *)oh_name;
+			int n = buff_size - 1;
+			while (n > 0 && *ascii_oh_name) {
+				*name = *ascii_oh_name;
+				name++;
+				ascii_oh_name++;
+				n--;
+			}
+		} else {
+			strncpy(name, oh_name + 1, buff_size - 1);
+		}
+	} else {
+#else
+	{
+#endif
+		strncpy(name, oh_name, buff_size - 1);
+	}
+}
+
+static void yaffs_load_oh_from_name(struct yaffs_dev *dev, YCHAR *oh_name,
+				    const YCHAR *name)
+{
+#ifdef CONFIG_YAFFS_AUTO_UNICODE
+
+	int is_ascii;
+	YCHAR *w;
+
+	if (dev->param.auto_unicode) {
+
+		is_ascii = 1;
+		w = name;
+
+		/* Figure out if the name will fit in ascii character set */
+		while (is_ascii && *w) {
+			if ((*w) & 0xff00)
+				is_ascii = 0;
+			w++;
+		}
+
+		if (is_ascii) {
+			/* It is an ASCII name, so convert unicode to ascii */
+			char *ascii_oh_name = (char *)oh_name;
+			int n = YAFFS_MAX_NAME_LENGTH - 1;
+			while (n > 0 && *name) {
+				*ascii_oh_name = *name;
+				name++;
+				ascii_oh_name++;
+				n--;
+			}
+		} else {
+			/* Unicode name, so save starting at the second YCHAR */
+			*oh_name = 0;
+			strncpy(oh_name + 1, name,
+					YAFFS_MAX_NAME_LENGTH - 2);
+		}
+	} else {
+#else
+	{
+#endif
+		strncpy(oh_name, name, YAFFS_MAX_NAME_LENGTH - 1);
+	}
+}
+
+/* UpdateObjectHeader updates the header on NAND for an object.
+ * If name is not NULL, then that new name is used.
+ */
+int yaffs_update_oh(struct yaffs_obj *in, const YCHAR *name, int force,
+		    int is_shrink, int shadows, struct yaffs_xattr_mod *xmod)
+{
+
+	struct yaffs_block_info *bi;
+	struct yaffs_dev *dev = in->my_dev;
+	int prev_chunk_id;
+	int ret_val = 0;
+	int result = 0;
+	int new_chunk_id;
+	struct yaffs_ext_tags new_tags;
+	struct yaffs_ext_tags old_tags;
+	const YCHAR *alias = NULL;
+	u8 *buffer = NULL;
+	YCHAR old_name[YAFFS_MAX_NAME_LENGTH + 1];
+	struct yaffs_obj_hdr *oh = NULL;
+
+	strcpy(old_name, _Y("silly old name"));
+
+	if (!in->fake || in == dev->root_dir ||
+	    force || xmod) {
+
+		yaffs_check_gc(dev, 0);
+		yaffs_check_obj_details_loaded(in);
+
+		buffer = yaffs_get_temp_buffer(in->my_dev, __LINE__);
+		oh = (struct yaffs_obj_hdr *)buffer;
+
+		prev_chunk_id = in->hdr_chunk;
+
+		if (prev_chunk_id > 0) {
+			result = yaffs_rd_chunk_tags_nand(dev, prev_chunk_id,
+							  buffer, &old_tags);
+
+			yaffs_verify_oh(in, oh, &old_tags, 0);
+
+			memcpy(old_name, oh->name, sizeof(oh->name));
+			memset(buffer, 0xFF, sizeof(struct yaffs_obj_hdr));
+		} else {
+			memset(buffer, 0xFF, dev->data_bytes_per_chunk);
+		}
+
+		oh->type = in->variant_type;
+		oh->yst_mode = in->yst_mode;
+		oh->shadows_obj = oh->inband_shadowed_obj_id = shadows;
+
+		yaffs_load_attribs_oh(oh, in);
+
+		if (in->parent)
+			oh->parent_obj_id = in->parent->obj_id;
+		else
+			oh->parent_obj_id = 0;
+
+		if (name && *name) {
+			memset(oh->name, 0, sizeof(oh->name));
+			yaffs_load_oh_from_name(dev, oh->name, name);
+		} else if (prev_chunk_id > 0) {
+			memcpy(oh->name, old_name, sizeof(oh->name));
+		} else {
+			memset(oh->name, 0, sizeof(oh->name));
+		}
+
+		oh->is_shrink = is_shrink;
+
+		switch (in->variant_type) {
+		case YAFFS_OBJECT_TYPE_UNKNOWN:
+			/* Should not happen */
+			break;
+		case YAFFS_OBJECT_TYPE_FILE:
+			oh->file_size =
+			    (oh->parent_obj_id == YAFFS_OBJECTID_DELETED
+			     || oh->parent_obj_id ==
+			     YAFFS_OBJECTID_UNLINKED) ? 0 : in->
+			    variant.file_variant.file_size;
+			break;
+		case YAFFS_OBJECT_TYPE_HARDLINK:
+			oh->equiv_id = in->variant.hardlink_variant.equiv_id;
+			break;
+		case YAFFS_OBJECT_TYPE_SPECIAL:
+			/* Do nothing */
+			break;
+		case YAFFS_OBJECT_TYPE_DIRECTORY:
+			/* Do nothing */
+			break;
+		case YAFFS_OBJECT_TYPE_SYMLINK:
+			alias = in->variant.symlink_variant.alias;
+			if (!alias)
+				alias = _Y("no alias");
+			strncpy(oh->alias, alias, YAFFS_MAX_ALIAS_LENGTH);
+			oh->alias[YAFFS_MAX_ALIAS_LENGTH] = 0;
+			break;
+		}
+
+		/* process any xattrib modifications */
+		if (xmod)
+			yaffs_apply_xattrib_mod(in, (char *)buffer, xmod);
+
+		/* Tags */
+		yaffs_init_tags(&new_tags);
+		in->serial++;
+		new_tags.chunk_id = 0;
+		new_tags.obj_id = in->obj_id;
+		new_tags.serial_number = in->serial;
+
+		/* Add extra info for file header */
+		new_tags.extra_available = 1;
+		new_tags.extra_parent_id = oh->parent_obj_id;
+		new_tags.extra_length = oh->file_size;
+		new_tags.extra_is_shrink = oh->is_shrink;
+		new_tags.extra_equiv_id = oh->equiv_id;
+		new_tags.extra_shadows = (oh->shadows_obj > 0) ? 1 : 0;
+		new_tags.extra_obj_type = in->variant_type;
+		yaffs_verify_oh(in, oh, &new_tags, 1);
+
+		/* Create new chunk in NAND */
+		new_chunk_id =
+		    yaffs_write_new_chunk(dev, buffer, &new_tags,
+					  (prev_chunk_id > 0) ? 1 : 0);
+
+		if (new_chunk_id >= 0) {
+
+			in->hdr_chunk = new_chunk_id;
+
+			if (prev_chunk_id > 0) {
+				yaffs_chunk_del(dev, prev_chunk_id, 1,
+						__LINE__);
+			}
+
+			if (!yaffs_obj_cache_dirty(in))
+				in->dirty = 0;
+
+			/* If this was a shrink, then mark the block
+			 * that the chunk lives on */
+			if (is_shrink) {
+				bi = yaffs_get_block_info(in->my_dev,
+							  new_chunk_id /
+							  in->my_dev->param.
+							  chunks_per_block);
+				bi->has_shrink_hdr = 1;
+			}
+		}
+		ret_val = new_chunk_id;
+	}
+
+	if (buffer)
+		yaffs_release_temp_buffer(dev, buffer, __LINE__);
+
+	return ret_val;
+}
+
+/*--------------------- File read/write ------------------------
+ * Read and write have very similar structures.
+ * In general the read/write has three parts to it
+ * An incomplete chunk to start with (if the read/write is not chunk-aligned)
+ * Some complete chunks
+ * An incomplete chunk to end off with
+ *
+ * Curve-balls: the first chunk might also be the last chunk.
+ */
+
+int yaffs_file_rd(struct yaffs_obj *in, u8 * buffer, loff_t offset, int n_bytes)
+{
+	int chunk;
+	u32 start;
+	int n_copy;
+	int n = n_bytes;
+	int n_done = 0;
+	struct yaffs_cache *cache;
+	struct yaffs_dev *dev;
+
+	dev = in->my_dev;
+
+	while (n > 0) {
+		yaffs_addr_to_chunk(dev, offset, &chunk, &start);
+		chunk++;
+
+		/* OK now check for the curveball where the start and end are in
+		 * the same chunk.
+		 */
+		if ((start + n) < dev->data_bytes_per_chunk)
+			n_copy = n;
+		else
+			n_copy = dev->data_bytes_per_chunk - start;
+
+		cache = yaffs_find_chunk_cache(in, chunk);
+
+		/* If the chunk is already in the cache or it is less than
+		 * a whole chunk or we're using inband tags then use the cache
+		 * (if there is caching) else bypass the cache.
+		 */
+		if (cache || n_copy != dev->data_bytes_per_chunk
+		    || dev->param.inband_tags) {
+			if (dev->param.n_caches > 0) {
+
+				/* If we can't find the data in the cache,
+				 * then load it up. */
+
+				if (!cache) {
+					cache =
+					    yaffs_grab_chunk_cache(in->my_dev);
+					cache->object = in;
+					cache->chunk_id = chunk;
+					cache->dirty = 0;
+					cache->locked = 0;
+					yaffs_rd_data_obj(in, chunk,
+							  cache->data);
+					cache->n_bytes = 0;
+				}
+
+				yaffs_use_cache(dev, cache, 0);
+
+				cache->locked = 1;
+
+				memcpy(buffer, &cache->data[start], n_copy);
+
+				cache->locked = 0;
+			} else {
+				/* Read into the local buffer then copy.. */
+
+				u8 *local_buffer =
+				    yaffs_get_temp_buffer(dev, __LINE__);
+				yaffs_rd_data_obj(in, chunk, local_buffer);
+
+				memcpy(buffer, &local_buffer[start], n_copy);
+
+				yaffs_release_temp_buffer(dev, local_buffer,
+							  __LINE__);
+			}
+		} else {
+			/* A full chunk. Read directly into the buffer. */
+			yaffs_rd_data_obj(in, chunk, buffer);
+		}
+		n -= n_copy;
+		offset += n_copy;
+		buffer += n_copy;
+		n_done += n_copy;
+	}
+	return n_done;
+}
+
+int yaffs_do_file_wr(struct yaffs_obj *in, const u8 *buffer, loff_t offset,
+		     int n_bytes, int write_trhrough)
+{
+
+	int chunk;
+	u32 start;
+	int n_copy;
+	int n = n_bytes;
+	int n_done = 0;
+	int n_writeback;
+	int start_write = offset;
+	int chunk_written = 0;
+	u32 n_bytes_read;
+	u32 chunk_start;
+	struct yaffs_dev *dev;
+
+	dev = in->my_dev;
+
+	while (n > 0 && chunk_written >= 0) {
+		yaffs_addr_to_chunk(dev, offset, &chunk, &start);
+
+		if (chunk * dev->data_bytes_per_chunk + start != offset ||
+		    start >= dev->data_bytes_per_chunk) {
+			yaffs_trace(YAFFS_TRACE_ERROR,
+				"AddrToChunk of offset %d gives chunk %d start %d",
+				(int)offset, chunk, start);
+		}
+		chunk++;	/* File pos to chunk in file offset */
+
+		/* OK now check for the curveball where the start and end are in
+		 * the same chunk.
+		 */
+
+		if ((start + n) < dev->data_bytes_per_chunk) {
+			n_copy = n;
+
+			/* Now calculate how many bytes to write back....
+			 * If we're overwriting and not writing to then end of
+			 * file then we need to write back as much as was there
+			 * before.
+			 */
+
+			chunk_start = ((chunk - 1) * dev->data_bytes_per_chunk);
+
+			if (chunk_start > in->variant.file_variant.file_size)
+				n_bytes_read = 0;	/* Past end of file */
+			else
+				n_bytes_read =
+				    in->variant.file_variant.file_size -
+				    chunk_start;
+
+			if (n_bytes_read > dev->data_bytes_per_chunk)
+				n_bytes_read = dev->data_bytes_per_chunk;
+
+			n_writeback =
+			    (n_bytes_read >
+			     (start + n)) ? n_bytes_read : (start + n);
+
+			if (n_writeback < 0 ||
+			    n_writeback > dev->data_bytes_per_chunk)
+				YBUG();
+
+		} else {
+			n_copy = dev->data_bytes_per_chunk - start;
+			n_writeback = dev->data_bytes_per_chunk;
+		}
+
+		if (n_copy != dev->data_bytes_per_chunk ||
+		    dev->param.inband_tags) {
+			/* An incomplete start or end chunk (or maybe both
+			 * start and end chunk), or we're using inband tags,
+			 * so we want to use the cache buffers.
+			 */
+			if (dev->param.n_caches > 0) {
+				struct yaffs_cache *cache;
+
+				/* If we can't find the data in the cache, then
+				 * load the cache */
+				cache = yaffs_find_chunk_cache(in, chunk);
+
+				if (!cache
+				    && yaffs_check_alloc_available(dev, 1)) {
+					cache = yaffs_grab_chunk_cache(dev);
+					cache->object = in;
+					cache->chunk_id = chunk;
+					cache->dirty = 0;
+					cache->locked = 0;
+					yaffs_rd_data_obj(in, chunk,
+							  cache->data);
+				} else if (cache &&
+					   !cache->dirty &&
+					   !yaffs_check_alloc_available(dev,
+									1)) {
+					/* Drop the cache if it was a read cache
+					 * item and no space check has been made
+					 * for it.
+					 */
+					cache = NULL;
+				}
+
+				if (cache) {
+					yaffs_use_cache(dev, cache, 1);
+					cache->locked = 1;
+
+					memcpy(&cache->data[start], buffer,
+					       n_copy);
+
+					cache->locked = 0;
+					cache->n_bytes = n_writeback;
+
+					if (write_trhrough) {
+						chunk_written =
+						    yaffs_wr_data_obj
+						    (cache->object,
+						     cache->chunk_id,
+						     cache->data,
+						     cache->n_bytes, 1);
+						cache->dirty = 0;
+					}
+				} else {
+					chunk_written = -1;	/* fail write */
+				}
+			} else {
+				/* An incomplete start or end chunk (or maybe
+				 * both start and end chunk). Read into the
+				 * local buffer then copy over and write back.
+				 */
+
+				u8 *local_buffer =
+				    yaffs_get_temp_buffer(dev, __LINE__);
+
+				yaffs_rd_data_obj(in, chunk, local_buffer);
+				memcpy(&local_buffer[start], buffer, n_copy);
+
+				chunk_written =
+				    yaffs_wr_data_obj(in, chunk,
+						      local_buffer,
+						      n_writeback, 0);
+
+				yaffs_release_temp_buffer(dev, local_buffer,
+							  __LINE__);
+			}
+		} else {
+			/* A full chunk. Write directly from the buffer. */
+
+			chunk_written =
+			    yaffs_wr_data_obj(in, chunk, buffer,
+					      dev->data_bytes_per_chunk, 0);
+
+			/* Since we've overwritten the cached data,
+			 * we better invalidate it. */
+			yaffs_invalidate_chunk_cache(in, chunk);
+		}
+
+		if (chunk_written >= 0) {
+			n -= n_copy;
+			offset += n_copy;
+			buffer += n_copy;
+			n_done += n_copy;
+		}
+	}
+
+	/* Update file object */
+
+	if ((start_write + n_done) > in->variant.file_variant.file_size)
+		in->variant.file_variant.file_size = (start_write + n_done);
+
+	in->dirty = 1;
+	return n_done;
+}
+
+int yaffs_wr_file(struct yaffs_obj *in, const u8 *buffer, loff_t offset,
+		  int n_bytes, int write_trhrough)
+{
+	yaffs2_handle_hole(in, offset);
+	return yaffs_do_file_wr(in, buffer, offset, n_bytes, write_trhrough);
+}
+
+/* ---------------------- File resizing stuff ------------------ */
+
+static void yaffs_prune_chunks(struct yaffs_obj *in, int new_size)
+{
+
+	struct yaffs_dev *dev = in->my_dev;
+	int old_size = in->variant.file_variant.file_size;
+	int i;
+	int chunk_id;
+	int last_del = 1 + (old_size - 1) / dev->data_bytes_per_chunk;
+	int start_del = 1 + (new_size + dev->data_bytes_per_chunk - 1) /
+	    dev->data_bytes_per_chunk;
+
+
+	/* Delete backwards so that we don't end up with holes if
+	 * power is lost part-way through the operation.
+	 */
+	for (i = last_del; i >= start_del; i--) {
+		/* NB this could be optimised somewhat,
+		 * eg. could retrieve the tags and write them without
+		 * using yaffs_chunk_del
+		 */
+
+		chunk_id = yaffs_find_del_file_chunk(in, i, NULL);
+		if (chunk_id > 0) {
+			if (chunk_id <
+			    (dev->internal_start_block *
+			     dev->param.chunks_per_block) ||
+			    chunk_id >=
+			    ((dev->internal_end_block + 1) *
+			      dev->param.chunks_per_block)) {
+				yaffs_trace(YAFFS_TRACE_ALWAYS,
+					"Found daft chunk_id %d for %d",
+					chunk_id, i);
+			} else {
+				in->n_data_chunks--;
+				yaffs_chunk_del(dev, chunk_id, 1, __LINE__);
+			}
+		}
+	}
+}
+
+void yaffs_resize_file_down(struct yaffs_obj *obj, loff_t new_size)
+{
+	int new_full;
+	u32 new_partial;
+	struct yaffs_dev *dev = obj->my_dev;
+
+	yaffs_addr_to_chunk(dev, new_size, &new_full, &new_partial);
+
+	yaffs_prune_chunks(obj, new_size);
+
+	if (new_partial != 0) {
+		int last_chunk = 1 + new_full;
+		u8 *local_buffer = yaffs_get_temp_buffer(dev, __LINE__);
+
+		/* Rewrite the last chunk with its new size and zero pad */
+		yaffs_rd_data_obj(obj, last_chunk, local_buffer);
+		memset(local_buffer + new_partial, 0,
+		       dev->data_bytes_per_chunk - new_partial);
+
+		yaffs_wr_data_obj(obj, last_chunk, local_buffer,
+				  new_partial, 1);
+
+		yaffs_release_temp_buffer(dev, local_buffer, __LINE__);
+	}
+
+	obj->variant.file_variant.file_size = new_size;
+
+	yaffs_prune_tree(dev, &obj->variant.file_variant);
+}
+
+int yaffs_resize_file(struct yaffs_obj *in, loff_t new_size)
+{
+	struct yaffs_dev *dev = in->my_dev;
+	int old_size = in->variant.file_variant.file_size;
+
+	yaffs_flush_file_cache(in);
+	yaffs_invalidate_whole_cache(in);
+
+	yaffs_check_gc(dev, 0);
+
+	if (in->variant_type != YAFFS_OBJECT_TYPE_FILE)
+		return YAFFS_FAIL;
+
+	if (new_size == old_size)
+		return YAFFS_OK;
+
+	if (new_size > old_size) {
+		yaffs2_handle_hole(in, new_size);
+		in->variant.file_variant.file_size = new_size;
+	} else {
+		/* new_size < old_size */
+		yaffs_resize_file_down(in, new_size);
+	}
+
+	/* Write a new object header to reflect the resize.
+	 * show we've shrunk the file, if need be
+	 * Do this only if the file is not in the deleted directories
+	 * and is not shadowed.
+	 */
+	if (in->parent &&
+	    !in->is_shadowed &&
+	    in->parent->obj_id != YAFFS_OBJECTID_UNLINKED &&
+	    in->parent->obj_id != YAFFS_OBJECTID_DELETED)
+		yaffs_update_oh(in, NULL, 0, 0, 0, NULL);
+
+	return YAFFS_OK;
+}
+
+int yaffs_flush_file(struct yaffs_obj *in, int update_time, int data_sync)
+{
+	int ret_val;
+
+	if (in->dirty) {
+		yaffs_flush_file_cache(in);
+		if (data_sync)	/* Only sync data */
+			ret_val = YAFFS_OK;
+		else {
+			if (update_time)
+				yaffs_load_current_time(in, 0, 0);
+
+			ret_val = (yaffs_update_oh(in, NULL, 0, 0, 0, NULL) >=
+				   0) ? YAFFS_OK : YAFFS_FAIL;
+		}
+	} else {
+		ret_val = YAFFS_OK;
+	}
+	return ret_val;
+}
+
+
+/* yaffs_del_file deletes the whole file data
+ * and the inode associated with the file.
+ * It does not delete the links associated with the file.
+ */
+static int yaffs_unlink_file_if_needed(struct yaffs_obj *in)
+{
+	int ret_val;
+	int del_now = 0;
+	struct yaffs_dev *dev = in->my_dev;
+
+	if (!in->my_inode)
+		del_now = 1;
+
+	if (del_now) {
+		ret_val =
+		    yaffs_change_obj_name(in, in->my_dev->del_dir,
+					  _Y("deleted"), 0, 0);
+		yaffs_trace(YAFFS_TRACE_TRACING,
+			"yaffs: immediate deletion of file %d",
+			in->obj_id);
+		in->deleted = 1;
+		in->my_dev->n_deleted_files++;
+		if (dev->param.disable_soft_del || dev->param.is_yaffs2)
+			yaffs_resize_file(in, 0);
+		yaffs_soft_del_file(in);
+	} else {
+		ret_val =
+		    yaffs_change_obj_name(in, in->my_dev->unlinked_dir,
+					  _Y("unlinked"), 0, 0);
+	}
+	return ret_val;
+}
+
+int yaffs_del_file(struct yaffs_obj *in)
+{
+	int ret_val = YAFFS_OK;
+	int deleted;	/* Need to cache value on stack if in is freed */
+	struct yaffs_dev *dev = in->my_dev;
+
+	if (dev->param.disable_soft_del || dev->param.is_yaffs2)
+		yaffs_resize_file(in, 0);
+
+	if (in->n_data_chunks > 0) {
+		/* Use soft deletion if there is data in the file.
+		 * That won't be the case if it has been resized to zero.
+		 */
+		if (!in->unlinked)
+			ret_val = yaffs_unlink_file_if_needed(in);
+
+		deleted = in->deleted;
+
+		if (ret_val == YAFFS_OK && in->unlinked && !in->deleted) {
+			in->deleted = 1;
+			deleted = 1;
+			in->my_dev->n_deleted_files++;
+			yaffs_soft_del_file(in);
+		}
+		return deleted ? YAFFS_OK : YAFFS_FAIL;
+	} else {
+		/* The file has no data chunks so we toss it immediately */
+		yaffs_free_tnode(in->my_dev, in->variant.file_variant.top);
+		in->variant.file_variant.top = NULL;
+		yaffs_generic_obj_del(in);
+
+		return YAFFS_OK;
+	}
+}
+
+int yaffs_is_non_empty_dir(struct yaffs_obj *obj)
+{
+	return (obj &&
+		obj->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY) &&
+		!(list_empty(&obj->variant.dir_variant.children));
+}
+
+static int yaffs_del_dir(struct yaffs_obj *obj)
+{
+	/* First check that the directory is empty. */
+	if (yaffs_is_non_empty_dir(obj))
+		return YAFFS_FAIL;
+
+	return yaffs_generic_obj_del(obj);
+}
+
+static int yaffs_del_symlink(struct yaffs_obj *in)
+{
+	kfree(in->variant.symlink_variant.alias);
+	in->variant.symlink_variant.alias = NULL;
+
+	return yaffs_generic_obj_del(in);
+}
+
+static int yaffs_del_link(struct yaffs_obj *in)
+{
+	/* remove this hardlink from the list associated with the equivalent
+	 * object
+	 */
+	list_del_init(&in->hard_links);
+	return yaffs_generic_obj_del(in);
+}
+
+int yaffs_del_obj(struct yaffs_obj *obj)
+{
+	int ret_val = -1;
+
+	switch (obj->variant_type) {
+	case YAFFS_OBJECT_TYPE_FILE:
+		ret_val = yaffs_del_file(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_DIRECTORY:
+		if (!list_empty(&obj->variant.dir_variant.dirty)) {
+			yaffs_trace(YAFFS_TRACE_BACKGROUND,
+				"Remove object %d from dirty directories",
+				obj->obj_id);
+			list_del_init(&obj->variant.dir_variant.dirty);
+		}
+		return yaffs_del_dir(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_SYMLINK:
+		ret_val = yaffs_del_symlink(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_HARDLINK:
+		ret_val = yaffs_del_link(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_SPECIAL:
+		ret_val = yaffs_generic_obj_del(obj);
+		break;
+	case YAFFS_OBJECT_TYPE_UNKNOWN:
+		ret_val = 0;
+		break;		/* should not happen. */
+	}
+	return ret_val;
+}
+
+static int yaffs_unlink_worker(struct yaffs_obj *obj)
+{
+	int del_now = 0;
+
+	if (!obj)
+		return YAFFS_FAIL;
+
+	if (!obj->my_inode)
+		del_now = 1;
+
+	yaffs_update_parent(obj->parent);
+
+	if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK) {
+		return yaffs_del_link(obj);
+	} else if (!list_empty(&obj->hard_links)) {
+		/* Curve ball: We're unlinking an object that has a hardlink.
+		 *
+		 * This problem arises because we are not strictly following
+		 * The Linux link/inode model.
+		 *
+		 * We can't really delete the object.
+		 * Instead, we do the following:
+		 * - Select a hardlink.
+		 * - Unhook it from the hard links
+		 * - Move it from its parent directory so that the rename works.
+		 * - Rename the object to the hardlink's name.
+		 * - Delete the hardlink
+		 */
+
+		struct yaffs_obj *hl;
+		struct yaffs_obj *parent;
+		int ret_val;
+		YCHAR name[YAFFS_MAX_NAME_LENGTH + 1];
+
+		hl = list_entry(obj->hard_links.next, struct yaffs_obj,
+				hard_links);
+
+		yaffs_get_obj_name(hl, name, YAFFS_MAX_NAME_LENGTH + 1);
+		parent = hl->parent;
+
+		list_del_init(&hl->hard_links);
+
+		yaffs_add_obj_to_dir(obj->my_dev->unlinked_dir, hl);
+
+		ret_val = yaffs_change_obj_name(obj, parent, name, 0, 0);
+
+		if (ret_val == YAFFS_OK)
+			ret_val = yaffs_generic_obj_del(hl);
+
+		return ret_val;
+
+	} else if (del_now) {
+		switch (obj->variant_type) {
+		case YAFFS_OBJECT_TYPE_FILE:
+			return yaffs_del_file(obj);
+			break;
+		case YAFFS_OBJECT_TYPE_DIRECTORY:
+			list_del_init(&obj->variant.dir_variant.dirty);
+			return yaffs_del_dir(obj);
+			break;
+		case YAFFS_OBJECT_TYPE_SYMLINK:
+			return yaffs_del_symlink(obj);
+			break;
+		case YAFFS_OBJECT_TYPE_SPECIAL:
+			return yaffs_generic_obj_del(obj);
+			break;
+		case YAFFS_OBJECT_TYPE_HARDLINK:
+		case YAFFS_OBJECT_TYPE_UNKNOWN:
+		default:
+			return YAFFS_FAIL;
+		}
+	} else if (yaffs_is_non_empty_dir(obj)) {
+		return YAFFS_FAIL;
+	} else {
+		return yaffs_change_obj_name(obj, obj->my_dev->unlinked_dir,
+						_Y("unlinked"), 0, 0);
+	}
+}
+
+static int yaffs_unlink_obj(struct yaffs_obj *obj)
+{
+	if (obj && obj->unlink_allowed)
+		return yaffs_unlink_worker(obj);
+
+	return YAFFS_FAIL;
+}
+
+int yaffs_unlinker(struct yaffs_obj *dir, const YCHAR *name)
+{
+	struct yaffs_obj *obj;
+
+	obj = yaffs_find_by_name(dir, name);
+	return yaffs_unlink_obj(obj);
+}
+
+/* Note:
+ * If old_name is NULL then we take old_dir as the object to be renamed.
+ */
+int yaffs_rename_obj(struct yaffs_obj *old_dir, const YCHAR *old_name,
+		     struct yaffs_obj *new_dir, const YCHAR *new_name)
+{
+	struct yaffs_obj *obj = NULL;
+	struct yaffs_obj *existing_target = NULL;
+	int force = 0;
+	int result;
+	struct yaffs_dev *dev;
+
+	if (!old_dir || old_dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		YBUG();
+		return YAFFS_FAIL;
+	}
+	if (!new_dir || new_dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		YBUG();
+		return YAFFS_FAIL;
+	}
+
+	dev = old_dir->my_dev;
+
+#ifdef CONFIG_YAFFS_CASE_INSENSITIVE
+	/* Special case for case insemsitive systems.
+	 * While look-up is case insensitive, the name isn't.
+	 * Therefore we might want to change x.txt to X.txt
+	 */
+	if (old_dir == new_dir &&
+		old_name && new_name &&
+		strcmp(old_name, new_name) == 0)
+		force = 1;
+#endif
+
+	if (strnlen(new_name, YAFFS_MAX_NAME_LENGTH + 1) >
+	    YAFFS_MAX_NAME_LENGTH)
+		/* ENAMETOOLONG */
+		return YAFFS_FAIL;
+
+	if (old_name)
+		obj = yaffs_find_by_name(old_dir, old_name);
+	else{
+		obj = old_dir;
+		old_dir = obj->parent;
+	}
+
+	if (obj && obj->rename_allowed) {
+		/* Now handle an existing target, if there is one */
+		existing_target = yaffs_find_by_name(new_dir, new_name);
+		if (yaffs_is_non_empty_dir(existing_target)) {
+			return YAFFS_FAIL;	/* ENOTEMPTY */
+		} else if (existing_target && existing_target != obj) {
+			/* Nuke the target first, using shadowing,
+			 * but only if it isn't the same object.
+			 *
+			 * Note we must disable gc here otherwise it can mess
+			 * up the shadowing.
+			 *
+			 */
+			dev->gc_disable = 1;
+			yaffs_change_obj_name(obj, new_dir, new_name, force,
+					      existing_target->obj_id);
+			existing_target->is_shadowed = 1;
+			yaffs_unlink_obj(existing_target);
+			dev->gc_disable = 0;
+		}
+
+		result = yaffs_change_obj_name(obj, new_dir, new_name, 1, 0);
+
+		yaffs_update_parent(old_dir);
+		if (new_dir != old_dir)
+			yaffs_update_parent(new_dir);
+
+		return result;
+	}
+	return YAFFS_FAIL;
+}
+
+/*----------------------- Initialisation Scanning ---------------------- */
+
+void yaffs_handle_shadowed_obj(struct yaffs_dev *dev, int obj_id,
+			       int backward_scanning)
+{
+	struct yaffs_obj *obj;
+
+	if (!backward_scanning) {
+		/* Handle YAFFS1 forward scanning case
+		 * For YAFFS1 we always do the deletion
+		 */
+
+	} else {
+		/* Handle YAFFS2 case (backward scanning)
+		 * If the shadowed object exists then ignore.
+		 */
+		obj = yaffs_find_by_number(dev, obj_id);
+		if (obj)
+			return;
+	}
+
+	/* Let's create it (if it does not exist) assuming it is a file so that
+	 * it can do shrinking etc.
+	 * We put it in unlinked dir to be cleaned up after the scanning
+	 */
+	obj =
+	    yaffs_find_or_create_by_number(dev, obj_id, YAFFS_OBJECT_TYPE_FILE);
+	if (!obj)
+		return;
+	obj->is_shadowed = 1;
+	yaffs_add_obj_to_dir(dev->unlinked_dir, obj);
+	obj->variant.file_variant.shrink_size = 0;
+	obj->valid = 1;		/* So that we don't read any other info. */
+}
+
+void yaffs_link_fixup(struct yaffs_dev *dev, struct yaffs_obj *hard_list)
+{
+	struct yaffs_obj *hl;
+	struct yaffs_obj *in;
+
+	while (hard_list) {
+		hl = hard_list;
+		hard_list = (struct yaffs_obj *)(hard_list->hard_links.next);
+
+		in = yaffs_find_by_number(dev,
+					  hl->variant.
+					  hardlink_variant.equiv_id);
+
+		if (in) {
+			/* Add the hardlink pointers */
+			hl->variant.hardlink_variant.equiv_obj = in;
+			list_add(&hl->hard_links, &in->hard_links);
+		} else {
+			/* Todo Need to report/handle this better.
+			 * Got a problem... hardlink to a non-existant object
+			 */
+			hl->variant.hardlink_variant.equiv_obj = NULL;
+			INIT_LIST_HEAD(&hl->hard_links);
+		}
+	}
+}
+
+static void yaffs_strip_deleted_objs(struct yaffs_dev *dev)
+{
+	/*
+	 *  Sort out state of unlinked and deleted objects after scanning.
+	 */
+	struct list_head *i;
+	struct list_head *n;
+	struct yaffs_obj *l;
+
+	if (dev->read_only)
+		return;
+
+	/* Soft delete all the unlinked files */
+	list_for_each_safe(i, n,
+			   &dev->unlinked_dir->variant.dir_variant.children) {
+		l = list_entry(i, struct yaffs_obj, siblings);
+		yaffs_del_obj(l);
+	}
+
+	list_for_each_safe(i, n, &dev->del_dir->variant.dir_variant.children) {
+		l = list_entry(i, struct yaffs_obj, siblings);
+		yaffs_del_obj(l);
+	}
+}
+
+/*
+ * This code iterates through all the objects making sure that they are rooted.
+ * Any unrooted objects are re-rooted in lost+found.
+ * An object needs to be in one of:
+ * - Directly under deleted, unlinked
+ * - Directly or indirectly under root.
+ *
+ * Note:
+ *  This code assumes that we don't ever change the current relationships
+ *  between directories:
+ *   root_dir->parent == unlinked_dir->parent == del_dir->parent == NULL
+ *   lost-n-found->parent == root_dir
+ *
+ * This fixes the problem where directories might have inadvertently been
+ * deleted leaving the object "hanging" without being rooted in the
+ * directory tree.
+ */
+
+static int yaffs_has_null_parent(struct yaffs_dev *dev, struct yaffs_obj *obj)
+{
+	return (obj == dev->del_dir ||
+		obj == dev->unlinked_dir || obj == dev->root_dir);
+}
+
+static void yaffs_fix_hanging_objs(struct yaffs_dev *dev)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_obj *parent;
+	int i;
+	struct list_head *lh;
+	struct list_head *n;
+	int depth_limit;
+	int hanging;
+
+	if (dev->read_only)
+		return;
+
+	/* Iterate through the objects in each hash entry,
+	 * looking at each object.
+	 * Make sure it is rooted.
+	 */
+
+	for (i = 0; i < YAFFS_NOBJECT_BUCKETS; i++) {
+		list_for_each_safe(lh, n, &dev->obj_bucket[i].list) {
+			obj = list_entry(lh, struct yaffs_obj, hash_link);
+			parent = obj->parent;
+
+			if (yaffs_has_null_parent(dev, obj)) {
+				/* These directories are not hanging */
+				hanging = 0;
+			} else if (!parent ||
+				   parent->variant_type !=
+				   YAFFS_OBJECT_TYPE_DIRECTORY) {
+				hanging = 1;
+			} else if (yaffs_has_null_parent(dev, parent)) {
+				hanging = 0;
+			} else {
+				/*
+				 * Need to follow the parent chain to
+				 * see if it is hanging.
+				 */
+				hanging = 0;
+				depth_limit = 100;
+
+				while (parent != dev->root_dir &&
+				       parent->parent &&
+				       parent->parent->variant_type ==
+				       YAFFS_OBJECT_TYPE_DIRECTORY &&
+				       depth_limit > 0) {
+					parent = parent->parent;
+					depth_limit--;
+				}
+				if (parent != dev->root_dir)
+					hanging = 1;
+			}
+			if (hanging) {
+				yaffs_trace(YAFFS_TRACE_SCAN,
+					"Hanging object %d moved to lost and found",
+					obj->obj_id);
+				yaffs_add_obj_to_dir(dev->lost_n_found, obj);
+			}
+		}
+	}
+}
+
+/*
+ * Delete directory contents for cleaning up lost and found.
+ */
+static void yaffs_del_dir_contents(struct yaffs_obj *dir)
+{
+	struct yaffs_obj *obj;
+	struct list_head *lh;
+	struct list_head *n;
+
+	if (dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY)
+		YBUG();
+
+	list_for_each_safe(lh, n, &dir->variant.dir_variant.children) {
+		obj = list_entry(lh, struct yaffs_obj, siblings);
+		if (obj->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY)
+			yaffs_del_dir_contents(obj);
+		yaffs_trace(YAFFS_TRACE_SCAN,
+			"Deleting lost_found object %d",
+			obj->obj_id);
+		yaffs_unlink_obj(obj);
+	}
+}
+
+static void yaffs_empty_l_n_f(struct yaffs_dev *dev)
+{
+	yaffs_del_dir_contents(dev->lost_n_found);
+}
+
+
+struct yaffs_obj *yaffs_find_by_name(struct yaffs_obj *directory,
+				     const YCHAR *name)
+{
+	int sum;
+	struct list_head *i;
+	YCHAR buffer[YAFFS_MAX_NAME_LENGTH + 1];
+	struct yaffs_obj *l;
+
+	if (!name)
+		return NULL;
+
+	if (!directory) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"tragedy: yaffs_find_by_name: null pointer directory"
+			);
+		YBUG();
+		return NULL;
+	}
+	if (directory->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"tragedy: yaffs_find_by_name: non-directory"
+			);
+		YBUG();
+	}
+
+	sum = yaffs_calc_name_sum(name);
+
+	list_for_each(i, &directory->variant.dir_variant.children) {
+		l = list_entry(i, struct yaffs_obj, siblings);
+
+		if (l->parent != directory)
+			YBUG();
+
+		yaffs_check_obj_details_loaded(l);
+
+		/* Special case for lost-n-found */
+		if (l->obj_id == YAFFS_OBJECTID_LOSTNFOUND) {
+			if (!strcmp(name, YAFFS_LOSTNFOUND_NAME))
+				return l;
+		} else if (l->sum == sum
+			   || l->hdr_chunk <= 0) {
+			/* LostnFound chunk called Objxxx
+			 * Do a real check
+			 */
+			yaffs_get_obj_name(l, buffer,
+				YAFFS_MAX_NAME_LENGTH + 1);
+			if (strncmp(name, buffer, YAFFS_MAX_NAME_LENGTH) == 0)
+				return l;
+		}
+	}
+	return NULL;
+}
+
+/* GetEquivalentObject dereferences any hard links to get to the
+ * actual object.
+ */
+
+struct yaffs_obj *yaffs_get_equivalent_obj(struct yaffs_obj *obj)
+{
+	if (obj && obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK) {
+		obj = obj->variant.hardlink_variant.equiv_obj;
+		yaffs_check_obj_details_loaded(obj);
+	}
+	return obj;
+}
+
+/*
+ *  A note or two on object names.
+ *  * If the object name is missing, we then make one up in the form objnnn
+ *
+ *  * ASCII names are stored in the object header's name field from byte zero
+ *  * Unicode names are historically stored starting from byte zero.
+ *
+ * Then there are automatic Unicode names...
+ * The purpose of these is to save names in a way that can be read as
+ * ASCII or Unicode names as appropriate, thus allowing a Unicode and ASCII
+ * system to share files.
+ *
+ * These automatic unicode are stored slightly differently...
+ *  - If the name can fit in the ASCII character space then they are saved as
+ *    ascii names as per above.
+ *  - If the name needs Unicode then the name is saved in Unicode
+ *    starting at oh->name[1].
+
+ */
+static void yaffs_fix_null_name(struct yaffs_obj *obj, YCHAR *name,
+				int buffer_size)
+{
+	/* Create an object name if we could not find one. */
+	if (strnlen(name, YAFFS_MAX_NAME_LENGTH) == 0) {
+		YCHAR local_name[20];
+		YCHAR num_string[20];
+		YCHAR *x = &num_string[19];
+		unsigned v = obj->obj_id;
+		num_string[19] = 0;
+		while (v > 0) {
+			x--;
+			*x = '0' + (v % 10);
+			v /= 10;
+		}
+		/* make up a name */
+		strcpy(local_name, YAFFS_LOSTNFOUND_PREFIX);
+		strcat(local_name, x);
+		strncpy(name, local_name, buffer_size - 1);
+	}
+}
+
+int yaffs_get_obj_name(struct yaffs_obj *obj, YCHAR *name, int buffer_size)
+{
+	memset(name, 0, buffer_size * sizeof(YCHAR));
+	yaffs_check_obj_details_loaded(obj);
+	if (obj->obj_id == YAFFS_OBJECTID_LOSTNFOUND)
+		strncpy(name, YAFFS_LOSTNFOUND_NAME, buffer_size - 1);
+#ifndef CONFIG_YAFFS_NO_SHORT_NAMES
+	else if (obj->short_name[0])
+		strcpy(name, obj->short_name);
+#endif
+	else if (obj->hdr_chunk > 0) {
+		int result;
+		u8 *buffer = yaffs_get_temp_buffer(obj->my_dev, __LINE__);
+
+		struct yaffs_obj_hdr *oh = (struct yaffs_obj_hdr *)buffer;
+
+		memset(buffer, 0, obj->my_dev->data_bytes_per_chunk);
+
+		if (obj->hdr_chunk > 0) {
+			result = yaffs_rd_chunk_tags_nand(obj->my_dev,
+							  obj->hdr_chunk,
+							  buffer, NULL);
+		}
+		yaffs_load_name_from_oh(obj->my_dev, name, oh->name,
+					buffer_size);
+
+		yaffs_release_temp_buffer(obj->my_dev, buffer, __LINE__);
+	}
+
+	yaffs_fix_null_name(obj, name, buffer_size);
+
+	return strnlen(name, YAFFS_MAX_NAME_LENGTH);
+}
+
+int yaffs_get_obj_length(struct yaffs_obj *obj)
+{
+	/* Dereference any hard linking */
+	obj = yaffs_get_equivalent_obj(obj);
+
+	if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
+		return obj->variant.file_variant.file_size;
+	if (obj->variant_type == YAFFS_OBJECT_TYPE_SYMLINK) {
+		if (!obj->variant.symlink_variant.alias)
+			return 0;
+		return strnlen(obj->variant.symlink_variant.alias,
+				     YAFFS_MAX_ALIAS_LENGTH);
+	} else {
+		/* Only a directory should drop through to here */
+		return obj->my_dev->data_bytes_per_chunk;
+	}
+}
+
+int yaffs_get_obj_link_count(struct yaffs_obj *obj)
+{
+	int count = 0;
+	struct list_head *i;
+
+	if (!obj->unlinked)
+		count++;	/* the object itself */
+
+	list_for_each(i, &obj->hard_links)
+	    count++;		/* add the hard links; */
+
+	return count;
+}
+
+int yaffs_get_obj_inode(struct yaffs_obj *obj)
+{
+	obj = yaffs_get_equivalent_obj(obj);
+
+	return obj->obj_id;
+}
+
+unsigned yaffs_get_obj_type(struct yaffs_obj *obj)
+{
+	obj = yaffs_get_equivalent_obj(obj);
+
+	switch (obj->variant_type) {
+	case YAFFS_OBJECT_TYPE_FILE:
+		return DT_REG;
+		break;
+	case YAFFS_OBJECT_TYPE_DIRECTORY:
+		return DT_DIR;
+		break;
+	case YAFFS_OBJECT_TYPE_SYMLINK:
+		return DT_LNK;
+		break;
+	case YAFFS_OBJECT_TYPE_HARDLINK:
+		return DT_REG;
+		break;
+	case YAFFS_OBJECT_TYPE_SPECIAL:
+		if (S_ISFIFO(obj->yst_mode))
+			return DT_FIFO;
+		if (S_ISCHR(obj->yst_mode))
+			return DT_CHR;
+		if (S_ISBLK(obj->yst_mode))
+			return DT_BLK;
+		if (S_ISSOCK(obj->yst_mode))
+			return DT_SOCK;
+		return DT_REG;
+		break;
+	default:
+		return DT_REG;
+		break;
+	}
+}
+
+YCHAR *yaffs_get_symlink_alias(struct yaffs_obj *obj)
+{
+	obj = yaffs_get_equivalent_obj(obj);
+	if (obj->variant_type == YAFFS_OBJECT_TYPE_SYMLINK)
+		return yaffs_clone_str(obj->variant.symlink_variant.alias);
+	else
+		return yaffs_clone_str(_Y(""));
+}
+
+/*--------------------------- Initialisation code -------------------------- */
+
+static int yaffs_check_dev_fns(const struct yaffs_dev *dev)
+{
+	/* Common functions, gotta have */
+	if (!dev->param.erase_fn || !dev->param.initialise_flash_fn)
+		return 0;
+
+#ifdef CONFIG_YAFFS_YAFFS2
+
+	/* Can use the "with tags" style interface for yaffs1 or yaffs2 */
+	if (dev->param.write_chunk_tags_fn &&
+	    dev->param.read_chunk_tags_fn &&
+	    !dev->param.write_chunk_fn &&
+	    !dev->param.read_chunk_fn &&
+	    dev->param.bad_block_fn && dev->param.query_block_fn)
+		return 1;
+#endif
+
+	/* Can use the "spare" style interface for yaffs1 */
+	if (!dev->param.is_yaffs2 &&
+	    !dev->param.write_chunk_tags_fn &&
+	    !dev->param.read_chunk_tags_fn &&
+	    dev->param.write_chunk_fn &&
+	    dev->param.read_chunk_fn &&
+	    !dev->param.bad_block_fn && !dev->param.query_block_fn)
+		return 1;
+
+	return 0;		/* bad */
+}
+
+static int yaffs_create_initial_dir(struct yaffs_dev *dev)
+{
+	/* Initialise the unlinked, deleted, root and lost+found directories */
+	dev->lost_n_found = dev->root_dir = NULL;
+	dev->unlinked_dir = dev->del_dir = NULL;
+	dev->unlinked_dir =
+	    yaffs_create_fake_dir(dev, YAFFS_OBJECTID_UNLINKED, S_IFDIR);
+	dev->del_dir =
+	    yaffs_create_fake_dir(dev, YAFFS_OBJECTID_DELETED, S_IFDIR);
+	dev->root_dir =
+	    yaffs_create_fake_dir(dev, YAFFS_OBJECTID_ROOT,
+				  YAFFS_ROOT_MODE | S_IFDIR);
+	dev->lost_n_found =
+	    yaffs_create_fake_dir(dev, YAFFS_OBJECTID_LOSTNFOUND,
+				  YAFFS_LOSTNFOUND_MODE | S_IFDIR);
+
+	if (dev->lost_n_found && dev->root_dir && dev->unlinked_dir
+	    && dev->del_dir) {
+		yaffs_add_obj_to_dir(dev->root_dir, dev->lost_n_found);
+		return YAFFS_OK;
+	}
+	return YAFFS_FAIL;
+}
+
+int yaffs_guts_initialise(struct yaffs_dev *dev)
+{
+	int init_failed = 0;
+	unsigned x;
+	int bits;
+
+	yaffs_trace(YAFFS_TRACE_TRACING, "yaffs: yaffs_guts_initialise()");
+
+	/* Check stuff that must be set */
+
+	if (!dev) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"yaffs: Need a device"
+			);
+		return YAFFS_FAIL;
+	}
+
+	dev->internal_start_block = dev->param.start_block;
+	dev->internal_end_block = dev->param.end_block;
+	dev->block_offset = 0;
+	dev->chunk_offset = 0;
+	dev->n_free_chunks = 0;
+
+	dev->gc_block = 0;
+
+	if (dev->param.start_block == 0) {
+		dev->internal_start_block = dev->param.start_block + 1;
+		dev->internal_end_block = dev->param.end_block + 1;
+		dev->block_offset = 1;
+		dev->chunk_offset = dev->param.chunks_per_block;
+	}
+
+	/* Check geometry parameters. */
+
+	if ((!dev->param.inband_tags && dev->param.is_yaffs2 &&
+		dev->param.total_bytes_per_chunk < 1024) ||
+		(!dev->param.is_yaffs2 &&
+			dev->param.total_bytes_per_chunk < 512) ||
+		(dev->param.inband_tags && !dev->param.is_yaffs2) ||
+		 dev->param.chunks_per_block < 2 ||
+		 dev->param.n_reserved_blocks < 2 ||
+		dev->internal_start_block <= 0 ||
+		dev->internal_end_block <= 0 ||
+		dev->internal_end_block <=
+		(dev->internal_start_block + dev->param.n_reserved_blocks + 2)
+		) {
+		/* otherwise it is too small */
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"NAND geometry problems: chunk size %d, type is yaffs%s, inband_tags %d ",
+			dev->param.total_bytes_per_chunk,
+			dev->param.is_yaffs2 ? "2" : "",
+			dev->param.inband_tags);
+		return YAFFS_FAIL;
+	}
+
+	if (yaffs_init_nand(dev) != YAFFS_OK) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "InitialiseNAND failed");
+		return YAFFS_FAIL;
+	}
+
+	/* Sort out space for inband tags, if required */
+	if (dev->param.inband_tags)
+		dev->data_bytes_per_chunk =
+		    dev->param.total_bytes_per_chunk -
+		    sizeof(struct yaffs_packed_tags2_tags_only);
+	else
+		dev->data_bytes_per_chunk = dev->param.total_bytes_per_chunk;
+
+	/* Got the right mix of functions? */
+	if (!yaffs_check_dev_fns(dev)) {
+		/* Function missing */
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"device function(s) missing or wrong");
+
+		return YAFFS_FAIL;
+	}
+
+	if (dev->is_mounted) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "device already mounted");
+		return YAFFS_FAIL;
+	}
+
+	/* Finished with most checks. Further checks happen later on too. */
+
+	dev->is_mounted = 1;
+
+	/* OK now calculate a few things for the device */
+
+	/*
+	 *  Calculate all the chunk size manipulation numbers:
+	 */
+	x = dev->data_bytes_per_chunk;
+	/* We always use dev->chunk_shift and dev->chunk_div */
+	dev->chunk_shift = calc_shifts(x);
+	x >>= dev->chunk_shift;
+	dev->chunk_div = x;
+	/* We only use chunk mask if chunk_div is 1 */
+	dev->chunk_mask = (1 << dev->chunk_shift) - 1;
+
+	/*
+	 * Calculate chunk_grp_bits.
+	 * We need to find the next power of 2 > than internal_end_block
+	 */
+
+	x = dev->param.chunks_per_block * (dev->internal_end_block + 1);
+
+	bits = calc_shifts_ceiling(x);
+
+	/* Set up tnode width if wide tnodes are enabled. */
+	if (!dev->param.wide_tnodes_disabled) {
+		/* bits must be even so that we end up with 32-bit words */
+		if (bits & 1)
+			bits++;
+		if (bits < 16)
+			dev->tnode_width = 16;
+		else
+			dev->tnode_width = bits;
+	} else {
+		dev->tnode_width = 16;
+	}
+
+	dev->tnode_mask = (1 << dev->tnode_width) - 1;
+
+	/* Level0 Tnodes are 16 bits or wider (if wide tnodes are enabled),
+	 * so if the bitwidth of the
+	 * chunk range we're using is greater than 16 we need
+	 * to figure out chunk shift and chunk_grp_size
+	 */
+
+	if (bits <= dev->tnode_width)
+		dev->chunk_grp_bits = 0;
+	else
+		dev->chunk_grp_bits = bits - dev->tnode_width;
+
+	dev->tnode_size = (dev->tnode_width * YAFFS_NTNODES_LEVEL0) / 8;
+	if (dev->tnode_size < sizeof(struct yaffs_tnode))
+		dev->tnode_size = sizeof(struct yaffs_tnode);
+
+	dev->chunk_grp_size = 1 << dev->chunk_grp_bits;
+
+	if (dev->param.chunks_per_block < dev->chunk_grp_size) {
+		/* We have a problem because the soft delete won't work if
+		 * the chunk group size > chunks per block.
+		 * This can be remedied by using larger "virtual blocks".
+		 */
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "chunk group too large");
+
+		return YAFFS_FAIL;
+	}
+
+	/* Finished verifying the device, continue with initialisation */
+
+	/* More device initialisation */
+	dev->all_gcs = 0;
+	dev->passive_gc_count = 0;
+	dev->oldest_dirty_gc_count = 0;
+	dev->bg_gcs = 0;
+	dev->gc_block_finder = 0;
+	dev->buffered_block = -1;
+	dev->doing_buffered_block_rewrite = 0;
+	dev->n_deleted_files = 0;
+	dev->n_bg_deletions = 0;
+	dev->n_unlinked_files = 0;
+	dev->n_ecc_fixed = 0;
+	dev->n_ecc_unfixed = 0;
+	dev->n_tags_ecc_fixed = 0;
+	dev->n_tags_ecc_unfixed = 0;
+	dev->n_erase_failures = 0;
+	dev->n_erased_blocks = 0;
+	dev->gc_disable = 0;
+	dev->has_pending_prioritised_gc = 1;
+		/* Assume the worst for now, will get fixed on first GC */
+	INIT_LIST_HEAD(&dev->dirty_dirs);
+	dev->oldest_dirty_seq = 0;
+	dev->oldest_dirty_block = 0;
+
+	/* Initialise temporary buffers and caches. */
+	if (!yaffs_init_tmp_buffers(dev))
+		init_failed = 1;
+
+	dev->cache = NULL;
+	dev->gc_cleanup_list = NULL;
+
+	if (!init_failed && dev->param.n_caches > 0) {
+		int i;
+		void *buf;
+		int cache_bytes =
+		    dev->param.n_caches * sizeof(struct yaffs_cache);
+
+		if (dev->param.n_caches > YAFFS_MAX_SHORT_OP_CACHES)
+			dev->param.n_caches = YAFFS_MAX_SHORT_OP_CACHES;
+
+		dev->cache = kmalloc(cache_bytes, GFP_NOFS);
+
+		buf = (u8 *) dev->cache;
+
+		if (dev->cache)
+			memset(dev->cache, 0, cache_bytes);
+
+		for (i = 0; i < dev->param.n_caches && buf; i++) {
+			dev->cache[i].object = NULL;
+			dev->cache[i].last_use = 0;
+			dev->cache[i].dirty = 0;
+			dev->cache[i].data = buf =
+			    kmalloc(dev->param.total_bytes_per_chunk, GFP_NOFS);
+		}
+		if (!buf)
+			init_failed = 1;
+
+		dev->cache_last_use = 0;
+	}
+
+	dev->cache_hits = 0;
+
+	if (!init_failed) {
+		dev->gc_cleanup_list =
+		    kmalloc(dev->param.chunks_per_block * sizeof(u32),
+					GFP_NOFS);
+		if (!dev->gc_cleanup_list)
+			init_failed = 1;
+	}
+
+	if (dev->param.is_yaffs2)
+		dev->param.use_header_file_size = 1;
+
+	if (!init_failed && !yaffs_init_blocks(dev))
+		init_failed = 1;
+
+	yaffs_init_tnodes_and_objs(dev);
+
+	if (!init_failed && !yaffs_create_initial_dir(dev))
+		init_failed = 1;
+
+	if (!init_failed) {
+		/* Now scan the flash. */
+		if (dev->param.is_yaffs2) {
+			if (yaffs2_checkpt_restore(dev)) {
+				yaffs_check_obj_details_loaded(dev->root_dir);
+				yaffs_trace(YAFFS_TRACE_CHECKPOINT |
+					YAFFS_TRACE_MOUNT,
+					"yaffs: restored from checkpoint"
+					);
+			} else {
+
+				/* Clean up the mess caused by an aborted
+				 * checkpoint load then scan backwards.
+				 */
+				yaffs_deinit_blocks(dev);
+
+				yaffs_deinit_tnodes_and_objs(dev);
+
+				dev->n_erased_blocks = 0;
+				dev->n_free_chunks = 0;
+				dev->alloc_block = -1;
+				dev->alloc_page = -1;
+				dev->n_deleted_files = 0;
+				dev->n_unlinked_files = 0;
+				dev->n_bg_deletions = 0;
+
+				if (!init_failed && !yaffs_init_blocks(dev))
+					init_failed = 1;
+
+				yaffs_init_tnodes_and_objs(dev);
+
+				if (!init_failed
+				    && !yaffs_create_initial_dir(dev))
+					init_failed = 1;
+
+				if (!init_failed && !yaffs2_scan_backwards(dev))
+					init_failed = 1;
+			}
+		} else if (!yaffs1_scan(dev)) {
+			init_failed = 1;
+		}
+
+		yaffs_strip_deleted_objs(dev);
+		yaffs_fix_hanging_objs(dev);
+		if (dev->param.empty_lost_n_found)
+			yaffs_empty_l_n_f(dev);
+	}
+
+	if (init_failed) {
+		/* Clean up the mess */
+		yaffs_trace(YAFFS_TRACE_TRACING,
+		  "yaffs: yaffs_guts_initialise() aborted.");
+
+		yaffs_deinitialise(dev);
+		return YAFFS_FAIL;
+	}
+
+	/* Zero out stats */
+	dev->n_page_reads = 0;
+	dev->n_page_writes = 0;
+	dev->n_erasures = 0;
+	dev->n_gc_copies = 0;
+	dev->n_retired_writes = 0;
+
+	dev->n_retired_blocks = 0;
+
+	yaffs_verify_free_chunks(dev);
+	yaffs_verify_blocks(dev);
+
+	/* Clean up any aborted checkpoint data */
+	if (!dev->is_checkpointed && dev->blocks_in_checkpt > 0)
+		yaffs2_checkpt_invalidate(dev);
+
+	yaffs_trace(YAFFS_TRACE_TRACING,
+	  "yaffs: yaffs_guts_initialise() done.");
+	return YAFFS_OK;
+}
+
+void yaffs_deinitialise(struct yaffs_dev *dev)
+{
+	if (dev->is_mounted) {
+		int i;
+
+		yaffs_deinit_blocks(dev);
+		yaffs_deinit_tnodes_and_objs(dev);
+		if (dev->param.n_caches > 0 && dev->cache) {
+
+			for (i = 0; i < dev->param.n_caches; i++) {
+				kfree(dev->cache[i].data);
+				dev->cache[i].data = NULL;
+			}
+
+			kfree(dev->cache);
+			dev->cache = NULL;
+		}
+
+		kfree(dev->gc_cleanup_list);
+
+		for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++)
+			kfree(dev->temp_buffer[i].buffer);
+
+		dev->is_mounted = 0;
+
+		if (dev->param.deinitialise_flash_fn)
+			dev->param.deinitialise_flash_fn(dev);
+	}
+}
+
+int yaffs_count_free_chunks(struct yaffs_dev *dev)
+{
+	int n_free = 0;
+	int b;
+	struct yaffs_block_info *blk;
+
+	blk = dev->block_info;
+	for (b = dev->internal_start_block; b <= dev->internal_end_block; b++) {
+		switch (blk->block_state) {
+		case YAFFS_BLOCK_STATE_EMPTY:
+		case YAFFS_BLOCK_STATE_ALLOCATING:
+		case YAFFS_BLOCK_STATE_COLLECTING:
+		case YAFFS_BLOCK_STATE_FULL:
+			n_free +=
+			    (dev->param.chunks_per_block - blk->pages_in_use +
+			     blk->soft_del_pages);
+			break;
+		default:
+			break;
+		}
+		blk++;
+	}
+	return n_free;
+}
+
+int yaffs_get_n_free_chunks(struct yaffs_dev *dev)
+{
+	/* This is what we report to the outside world */
+	int n_free;
+	int n_dirty_caches;
+	int blocks_for_checkpt;
+	int i;
+
+	n_free = dev->n_free_chunks;
+	n_free += dev->n_deleted_files;
+
+	/* Now count and subtract the number of dirty chunks in the cache. */
+
+	for (n_dirty_caches = 0, i = 0; i < dev->param.n_caches; i++) {
+		if (dev->cache[i].dirty)
+			n_dirty_caches++;
+	}
+
+	n_free -= n_dirty_caches;
+
+	n_free -=
+	    ((dev->param.n_reserved_blocks + 1) * dev->param.chunks_per_block);
+
+	/* Now figure checkpoint space and report that... */
+	blocks_for_checkpt = yaffs_calc_checkpt_blocks_required(dev);
+
+	n_free -= (blocks_for_checkpt * dev->param.chunks_per_block);
+
+	if (n_free < 0)
+		n_free = 0;
+
+	return n_free;
+}
diff --git a/fs/yaffs2/yaffs_guts.h b/fs/yaffs2/yaffs_guts.h
new file mode 100644
index 0000000..e4680e8
--- /dev/null
+++ b/fs/yaffs2/yaffs_guts.h
@@ -0,0 +1,938 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_GUTS_H__
+#define __YAFFS_GUTS_H__
+
+#include "yportenv.h"
+
+#define YAFFS_OK	1
+#define YAFFS_FAIL  0
+
+/* Give us a  Y=0x59,
+ * Give us an A=0x41,
+ * Give us an FF=0xFF
+ * Give us an S=0x53
+ * And what have we got...
+ */
+#define YAFFS_MAGIC			0x5941FF53
+
+#define YAFFS_NTNODES_LEVEL0		16
+#define YAFFS_TNODES_LEVEL0_BITS	4
+#define YAFFS_TNODES_LEVEL0_MASK	0xf
+
+#define YAFFS_NTNODES_INTERNAL		(YAFFS_NTNODES_LEVEL0 / 2)
+#define YAFFS_TNODES_INTERNAL_BITS	(YAFFS_TNODES_LEVEL0_BITS - 1)
+#define YAFFS_TNODES_INTERNAL_MASK	0x7
+#define YAFFS_TNODES_MAX_LEVEL		6
+
+#ifndef CONFIG_YAFFS_NO_YAFFS1
+#define YAFFS_BYTES_PER_SPARE		16
+#define YAFFS_BYTES_PER_CHUNK		512
+#define YAFFS_CHUNK_SIZE_SHIFT		9
+#define YAFFS_CHUNKS_PER_BLOCK		32
+#define YAFFS_BYTES_PER_BLOCK	(YAFFS_CHUNKS_PER_BLOCK*YAFFS_BYTES_PER_CHUNK)
+#endif
+
+#define YAFFS_MIN_YAFFS2_CHUNK_SIZE	1024
+#define YAFFS_MIN_YAFFS2_SPARE_SIZE	32
+
+#define YAFFS_MAX_CHUNK_ID		0x000FFFFF
+
+#define YAFFS_ALLOCATION_NOBJECTS	100
+#define YAFFS_ALLOCATION_NTNODES	100
+#define YAFFS_ALLOCATION_NLINKS		100
+
+#define YAFFS_NOBJECT_BUCKETS		256
+
+#define YAFFS_OBJECT_SPACE		0x40000
+#define YAFFS_MAX_OBJECT_ID		(YAFFS_OBJECT_SPACE - 1)
+
+#define YAFFS_CHECKPOINT_VERSION	4
+
+#ifdef CONFIG_YAFFS_UNICODE
+#define YAFFS_MAX_NAME_LENGTH		127
+#define YAFFS_MAX_ALIAS_LENGTH		79
+#else
+#define YAFFS_MAX_NAME_LENGTH		255
+#define YAFFS_MAX_ALIAS_LENGTH		159
+#endif
+
+#define YAFFS_SHORT_NAME_LENGTH		15
+
+/* Some special object ids for pseudo objects */
+#define YAFFS_OBJECTID_ROOT		1
+#define YAFFS_OBJECTID_LOSTNFOUND	2
+#define YAFFS_OBJECTID_UNLINKED		3
+#define YAFFS_OBJECTID_DELETED		4
+
+/* Pseudo object ids for checkpointing */
+#define YAFFS_OBJECTID_SB_HEADER	0x10
+#define YAFFS_OBJECTID_CHECKPOINT_DATA	0x20
+#define YAFFS_SEQUENCE_CHECKPOINT_DATA  0x21
+
+#define YAFFS_MAX_SHORT_OP_CACHES	20
+
+#define YAFFS_N_TEMP_BUFFERS		6
+
+/* We limit the number attempts at sucessfully saving a chunk of data.
+ * Small-page devices have 32 pages per block; large-page devices have 64.
+ * Default to something in the order of 5 to 10 blocks worth of chunks.
+ */
+#define YAFFS_WR_ATTEMPTS		(5*64)
+
+/* Sequence numbers are used in YAFFS2 to determine block allocation order.
+ * The range is limited slightly to help distinguish bad numbers from good.
+ * This also allows us to perhaps in the future use special numbers for
+ * special purposes.
+ * EFFFFF00 allows the allocation of 8 blocks/second (~1Mbytes) for 15 years,
+ * and is a larger number than the lifetime of a 2GB device.
+ */
+#define YAFFS_LOWEST_SEQUENCE_NUMBER	0x00001000
+#define YAFFS_HIGHEST_SEQUENCE_NUMBER	0xEFFFFF00
+
+/* Special sequence number for bad block that failed to be marked bad */
+#define YAFFS_SEQUENCE_BAD_BLOCK	0xFFFF0000
+
+/* ChunkCache is used for short read/write operations.*/
+struct yaffs_cache {
+	struct yaffs_obj *object;
+	int chunk_id;
+	int last_use;
+	int dirty;
+	int n_bytes;		/* Only valid if the cache is dirty */
+	int locked;		/* Can't push out or flush while locked. */
+	u8 *data;
+};
+
+/* Tags structures in RAM
+ * NB This uses bitfield. Bitfields should not straddle a u32 boundary
+ * otherwise the structure size will get blown out.
+ */
+
+#ifndef CONFIG_YAFFS_NO_YAFFS1
+struct yaffs_tags {
+	unsigned chunk_id:20;
+	unsigned serial_number:2;
+	unsigned n_bytes_lsb:10;
+	unsigned obj_id:18;
+	unsigned ecc:12;
+	unsigned n_bytes_msb:2;
+};
+
+union yaffs_tags_union {
+	struct yaffs_tags as_tags;
+	u8 as_bytes[8];
+};
+
+#endif
+
+/* Stuff used for extended tags in YAFFS2 */
+
+enum yaffs_ecc_result {
+	YAFFS_ECC_RESULT_UNKNOWN,
+	YAFFS_ECC_RESULT_NO_ERROR,
+	YAFFS_ECC_RESULT_FIXED,
+	YAFFS_ECC_RESULT_UNFIXED
+};
+
+enum yaffs_obj_type {
+	YAFFS_OBJECT_TYPE_UNKNOWN,
+	YAFFS_OBJECT_TYPE_FILE,
+	YAFFS_OBJECT_TYPE_SYMLINK,
+	YAFFS_OBJECT_TYPE_DIRECTORY,
+	YAFFS_OBJECT_TYPE_HARDLINK,
+	YAFFS_OBJECT_TYPE_SPECIAL
+};
+
+#define YAFFS_OBJECT_TYPE_MAX YAFFS_OBJECT_TYPE_SPECIAL
+
+struct yaffs_ext_tags {
+
+	unsigned validity0;
+	unsigned chunk_used;	/*  Status of the chunk: used or unused */
+	unsigned obj_id;	/* If 0 this is not used */
+	unsigned chunk_id;	/* If 0 this is a header, else a data chunk */
+	unsigned n_bytes;	/* Only valid for data chunks */
+
+	/* The following stuff only has meaning when we read */
+	enum yaffs_ecc_result ecc_result;
+	unsigned block_bad;
+
+	/* YAFFS 1 stuff */
+	unsigned is_deleted;	/* The chunk is marked deleted */
+	unsigned serial_number;	/* Yaffs1 2-bit serial number */
+
+	/* YAFFS2 stuff */
+	unsigned seq_number;	/* The sequence number of this block */
+
+	/* Extra info if this is an object header (YAFFS2 only) */
+
+	unsigned extra_available;	/* Extra info available if not zero */
+	unsigned extra_parent_id;	/* The parent object */
+	unsigned extra_is_shrink;	/* Is it a shrink header? */
+	unsigned extra_shadows;	/* Does this shadow another object? */
+
+	enum yaffs_obj_type extra_obj_type;	/* What object type? */
+
+	unsigned extra_length;	/* Length if it is a file */
+	unsigned extra_equiv_id;	/* Equivalent object for a hard link */
+
+	unsigned validity1;
+
+};
+
+/* Spare structure for YAFFS1 */
+struct yaffs_spare {
+	u8 tb0;
+	u8 tb1;
+	u8 tb2;
+	u8 tb3;
+	u8 page_status;		/* set to 0 to delete the chunk */
+	u8 block_status;
+	u8 tb4;
+	u8 tb5;
+	u8 ecc1[3];
+	u8 tb6;
+	u8 tb7;
+	u8 ecc2[3];
+};
+
+/*Special structure for passing through to mtd */
+struct yaffs_nand_spare {
+	struct yaffs_spare spare;
+	int eccres1;
+	int eccres2;
+};
+
+/* Block data in RAM */
+
+enum yaffs_block_state {
+	YAFFS_BLOCK_STATE_UNKNOWN = 0,
+
+	YAFFS_BLOCK_STATE_SCANNING,
+	/* Being scanned */
+
+	YAFFS_BLOCK_STATE_NEEDS_SCANNING,
+	/* The block might have something on it (ie it is allocating or full,
+	 * perhaps empty) but it needs to be scanned to determine its true
+	 * state.
+	 * This state is only valid during scanning.
+	 * NB We tolerate empty because the pre-scanner might be incapable of
+	 * deciding
+	 * However, if this state is returned on a YAFFS2 device,
+	 * then we expect a sequence number
+	 */
+
+	YAFFS_BLOCK_STATE_EMPTY,
+	/* This block is empty */
+
+	YAFFS_BLOCK_STATE_ALLOCATING,
+	/* This block is partially allocated.
+	 * At least one page holds valid data.
+	 * This is the one currently being used for page
+	 * allocation. Should never be more than one of these.
+	 * If a block is only partially allocated at mount it is treated as
+	 * full.
+	 */
+
+	YAFFS_BLOCK_STATE_FULL,
+	/* All the pages in this block have been allocated.
+	 * If a block was only partially allocated when mounted we treat
+	 * it as fully allocated.
+	 */
+
+	YAFFS_BLOCK_STATE_DIRTY,
+	/* The block was full and now all chunks have been deleted.
+	 * Erase me, reuse me.
+	 */
+
+	YAFFS_BLOCK_STATE_CHECKPOINT,
+	/* This block is assigned to holding checkpoint data. */
+
+	YAFFS_BLOCK_STATE_COLLECTING,
+	/* This block is being garbage collected */
+
+	YAFFS_BLOCK_STATE_DEAD
+	    /* This block has failed and is not in use */
+};
+
+#define	YAFFS_NUMBER_OF_BLOCK_STATES (YAFFS_BLOCK_STATE_DEAD + 1)
+
+struct yaffs_block_info {
+
+	int soft_del_pages:10;	/* number of soft deleted pages */
+	int pages_in_use:10;	/* number of pages in use */
+	unsigned block_state:4;	/* One of the above block states. */
+				/* NB use unsigned because enum is sometimes
+				 * an int */
+	u32 needs_retiring:1;	/* Data has failed on this block, */
+				/*need to get valid data off and retire*/
+	u32 skip_erased_check:1;/* Skip the erased check on this block */
+	u32 gc_prioritise:1;	/* An ECC check or blank check has failed.
+				   Block should be prioritised for GC */
+	u32 chunk_error_strikes:3;	/* How many times we've had ecc etc
+				failures on this block and tried to reuse it */
+
+#ifdef CONFIG_YAFFS_YAFFS2
+	u32 has_shrink_hdr:1;	/* This block has at least one shrink header */
+	u32 seq_number;		/* block sequence number for yaffs2 */
+#endif
+
+};
+
+/* -------------------------- Object structure -------------------------------*/
+/* This is the object structure as stored on NAND */
+
+struct yaffs_obj_hdr {
+	enum yaffs_obj_type type;
+
+	/* Apply to everything  */
+	int parent_obj_id;
+	u16 sum_no_longer_used;	/* checksum of name. No longer used */
+	YCHAR name[YAFFS_MAX_NAME_LENGTH + 1];
+
+	/* The following apply to all object types except for hard links */
+	u32 yst_mode;		/* protection */
+
+	u32 yst_uid;
+	u32 yst_gid;
+	u32 yst_atime;
+	u32 yst_mtime;
+	u32 yst_ctime;
+
+	/* File size  applies to files only */
+	int file_size;
+
+	/* Equivalent object id applies to hard links only. */
+	int equiv_id;
+
+	/* Alias is for symlinks only. */
+	YCHAR alias[YAFFS_MAX_ALIAS_LENGTH + 1];
+
+	u32 yst_rdev;	/* stuff for block and char devices (major/min) */
+
+	u32 win_ctime[2];
+	u32 win_atime[2];
+	u32 win_mtime[2];
+
+	u32 inband_shadowed_obj_id;
+	u32 inband_is_shrink;
+
+	u32 reserved[2];
+	int shadows_obj;	/* This object header shadows the
+				specified object if > 0 */
+
+	/* is_shrink applies to object headers written when wemake a hole. */
+	u32 is_shrink;
+
+};
+
+/*--------------------------- Tnode -------------------------- */
+
+struct yaffs_tnode {
+	struct yaffs_tnode *internal[YAFFS_NTNODES_INTERNAL];
+};
+
+/*------------------------  Object -----------------------------*/
+/* An object can be one of:
+ * - a directory (no data, has children links
+ * - a regular file (data.... not prunes :->).
+ * - a symlink [symbolic link] (the alias).
+ * - a hard link
+ */
+
+struct yaffs_file_var {
+	u32 file_size;
+	u32 scanned_size;
+	u32 shrink_size;
+	int top_level;
+	struct yaffs_tnode *top;
+};
+
+struct yaffs_dir_var {
+	struct list_head children;	/* list of child links */
+	struct list_head dirty;	/* Entry for list of dirty directories */
+};
+
+struct yaffs_symlink_var {
+	YCHAR *alias;
+};
+
+struct yaffs_hardlink_var {
+	struct yaffs_obj *equiv_obj;
+	u32 equiv_id;
+};
+
+union yaffs_obj_var {
+	struct yaffs_file_var file_variant;
+	struct yaffs_dir_var dir_variant;
+	struct yaffs_symlink_var symlink_variant;
+	struct yaffs_hardlink_var hardlink_variant;
+};
+
+struct yaffs_obj {
+	u8 deleted:1;		/* This should only apply to unlinked files. */
+	u8 soft_del:1;		/* it has also been soft deleted */
+	u8 unlinked:1;		/* An unlinked file.*/
+	u8 fake:1;		/* A fake object has no presence on NAND. */
+	u8 rename_allowed:1;	/* Some objects cannot be renamed. */
+	u8 unlink_allowed:1;
+	u8 dirty:1;		/* the object needs to be written to flash */
+	u8 valid:1;		/* When the file system is being loaded up, this
+				 * object might be created before the data
+				 * is available
+				 * ie. file data chunks encountered before
+				* the header.
+				 */
+	u8 lazy_loaded:1;	/* This object has been lazy loaded and
+				 * is missing some detail */
+
+	u8 defered_free:1;	/* Object is removed from NAND, but is
+				 * still in the inode cache.
+				 * Free of object is defered.
+				 * until the inode is released.
+				 */
+	u8 being_created:1;	/* This object is still being created
+				 * so skip some verification checks. */
+	u8 is_shadowed:1;	/* This object is shadowed on the way
+				 * to being renamed. */
+
+	u8 xattr_known:1;	/* We know if this has object has xattribs
+				 * or not. */
+	u8 has_xattr:1;		/* This object has xattribs.
+				 * Only valid if xattr_known. */
+
+	u8 serial;		/* serial number of chunk in NAND.*/
+	u16 sum;		/* sum of the name to speed searching */
+
+	struct yaffs_dev *my_dev;	/* The device I'm on */
+
+	struct list_head hash_link;	/* list of objects in hash bucket */
+
+	struct list_head hard_links;	/* hard linked object chain*/
+
+	/* directory structure stuff */
+	/* also used for linking up the free list */
+	struct yaffs_obj *parent;
+	struct list_head siblings;
+
+	/* Where's my object header in NAND? */
+	int hdr_chunk;
+
+	int n_data_chunks;	/* Number of data chunks for this file. */
+
+	u32 obj_id;		/* the object id value */
+
+	u32 yst_mode;
+
+#ifndef CONFIG_YAFFS_NO_SHORT_NAMES
+	YCHAR short_name[YAFFS_SHORT_NAME_LENGTH + 1];
+#endif
+
+#ifdef CONFIG_YAFFS_WINCE
+	u32 win_ctime[2];
+	u32 win_mtime[2];
+	u32 win_atime[2];
+#else
+	u32 yst_uid;
+	u32 yst_gid;
+	u32 yst_atime;
+	u32 yst_mtime;
+	u32 yst_ctime;
+#endif
+
+	u32 yst_rdev;
+
+	void *my_inode;
+
+	enum yaffs_obj_type variant_type;
+
+	union yaffs_obj_var variant;
+
+};
+
+struct yaffs_obj_bucket {
+	struct list_head list;
+	int count;
+};
+
+/* yaffs_checkpt_obj holds the definition of an object as dumped
+ * by checkpointing.
+ */
+
+struct yaffs_checkpt_obj {
+	int struct_type;
+	u32 obj_id;
+	u32 parent_id;
+	int hdr_chunk;
+	enum yaffs_obj_type variant_type:3;
+	u8 deleted:1;
+	u8 soft_del:1;
+	u8 unlinked:1;
+	u8 fake:1;
+	u8 rename_allowed:1;
+	u8 unlink_allowed:1;
+	u8 serial;
+	int n_data_chunks;
+	u32 size_or_equiv_obj;
+};
+
+/*--------------------- Temporary buffers ----------------
+ *
+ * These are chunk-sized working buffers. Each device has a few
+ */
+
+struct yaffs_buffer {
+	u8 *buffer;
+	int line;	/* track from whence this buffer was allocated */
+	int max_line;
+};
+
+/*----------------- Device ---------------------------------*/
+
+struct yaffs_param {
+	const YCHAR *name;
+
+	/*
+	 * Entry parameters set up way early. Yaffs sets up the rest.
+	 * The structure should be zeroed out before use so that unused
+	 * and defualt values are zero.
+	 */
+
+	int inband_tags;	/* Use unband tags */
+	u32 total_bytes_per_chunk;	/* Should be >= 512, does not need to
+					 be a power of 2 */
+	int chunks_per_block;	/* does not need to be a power of 2 */
+	int spare_bytes_per_chunk;	/* spare area size */
+	int start_block;	/* Start block we're allowed to use */
+	int end_block;		/* End block we're allowed to use */
+	int n_reserved_blocks;	/* Tuneable so that we can reduce
+				 * reserved blocks on NOR and RAM. */
+
+	int n_caches;		/* If <= 0, then short op caching is disabled,
+				 * else the number of short op caches.
+				 */
+	int use_nand_ecc;	/* Flag to decide whether or not to use
+				 * NAND driver ECC on data (yaffs1) */
+	int no_tags_ecc;	/* Flag to decide whether or not to do ECC
+				 * on packed tags (yaffs2) */
+
+	int is_yaffs2;		/* Use yaffs2 mode on this device */
+
+	int empty_lost_n_found;	/* Auto-empty lost+found directory on mount */
+
+	int refresh_period;	/* How often to check for a block refresh */
+
+	/* Checkpoint control. Can be set before or after initialisation */
+	u8 skip_checkpt_rd;
+	u8 skip_checkpt_wr;
+
+	int enable_xattr;	/* Enable xattribs */
+
+	/* NAND access functions (Must be set before calling YAFFS) */
+
+	int (*write_chunk_fn) (struct yaffs_dev *dev,
+			       int nand_chunk, const u8 *data,
+			       const struct yaffs_spare *spare);
+	int (*read_chunk_fn) (struct yaffs_dev *dev,
+			      int nand_chunk, u8 *data,
+			      struct yaffs_spare *spare);
+	int (*erase_fn) (struct yaffs_dev *dev, int flash_block);
+	int (*initialise_flash_fn) (struct yaffs_dev *dev);
+	int (*deinitialise_flash_fn) (struct yaffs_dev *dev);
+
+#ifdef CONFIG_YAFFS_YAFFS2
+	int (*write_chunk_tags_fn) (struct yaffs_dev *dev,
+				    int nand_chunk, const u8 *data,
+				    const struct yaffs_ext_tags *tags);
+	int (*read_chunk_tags_fn) (struct yaffs_dev *dev,
+				   int nand_chunk, u8 *data,
+				   struct yaffs_ext_tags *tags);
+	int (*bad_block_fn) (struct yaffs_dev *dev, int block_no);
+	int (*query_block_fn) (struct yaffs_dev *dev, int block_no,
+			       enum yaffs_block_state *state,
+			       u32 *seq_number);
+#endif
+
+	/* The remove_obj_fn function must be supplied by OS flavours that
+	 * need it.
+	 * yaffs direct uses it to implement the faster readdir.
+	 * Linux uses it to protect the directory during unlocking.
+	 */
+	void (*remove_obj_fn) (struct yaffs_obj *obj);
+
+	/* Callback to mark the superblock dirty */
+	void (*sb_dirty_fn) (struct yaffs_dev *dev);
+
+	/*  Callback to control garbage collection. */
+	unsigned (*gc_control) (struct yaffs_dev *dev);
+
+	/* Debug control flags. Don't use unless you know what you're doing */
+	int use_header_file_size;	/* Flag to determine if we should use
+					 * file sizes from the header */
+	int disable_lazy_load;	/* Disable lazy loading on this device */
+	int wide_tnodes_disabled;	/* Set to disable wide tnodes */
+	int disable_soft_del;	/* yaffs 1 only: Set to disable the use of
+				 * softdeletion. */
+
+	int defered_dir_update;	/* Set to defer directory updates */
+
+#ifdef CONFIG_YAFFS_AUTO_UNICODE
+	int auto_unicode;
+#endif
+	int always_check_erased;	/* Force chunk erased check always on */
+};
+
+struct yaffs_dev {
+	struct yaffs_param param;
+
+	/* Context storage. Holds extra OS specific data for this device */
+
+	void *os_context;
+	void *driver_context;
+
+	struct list_head dev_list;
+
+	/* Runtime parameters. Set up by YAFFS. */
+	int data_bytes_per_chunk;
+
+	/* Non-wide tnode stuff */
+	u16 chunk_grp_bits;	/* Number of bits that need to be resolved if
+				 * the tnodes are not wide enough.
+				 */
+	u16 chunk_grp_size;	/* == 2^^chunk_grp_bits */
+
+	/* Stuff to support wide tnodes */
+	u32 tnode_width;
+	u32 tnode_mask;
+	u32 tnode_size;
+
+	/* Stuff for figuring out file offset to chunk conversions */
+	u32 chunk_shift;	/* Shift value */
+	u32 chunk_div;		/* Divisor after shifting: 1 for 2^n sizes */
+	u32 chunk_mask;		/* Mask to use for power-of-2 case */
+
+	int is_mounted;
+	int read_only;
+	int is_checkpointed;
+
+	/* Stuff to support block offsetting to support start block zero */
+	int internal_start_block;
+	int internal_end_block;
+	int block_offset;
+	int chunk_offset;
+
+	/* Runtime checkpointing stuff */
+	int checkpt_page_seq;	/* running sequence number of checkpt pages */
+	int checkpt_byte_count;
+	int checkpt_byte_offs;
+	u8 *checkpt_buffer;
+	int checkpt_open_write;
+	int blocks_in_checkpt;
+	int checkpt_cur_chunk;
+	int checkpt_cur_block;
+	int checkpt_next_block;
+	int *checkpt_block_list;
+	int checkpt_max_blocks;
+	u32 checkpt_sum;
+	u32 checkpt_xor;
+
+	int checkpoint_blocks_required;	/* Number of blocks needed to store
+					 * current checkpoint set */
+
+	/* Block Info */
+	struct yaffs_block_info *block_info;
+	u8 *chunk_bits;		/* bitmap of chunks in use */
+	unsigned block_info_alt:1;	/* allocated using alternative alloc */
+	unsigned chunk_bits_alt:1;	/* allocated using alternative alloc */
+	int chunk_bit_stride;	/* Number of bytes of chunk_bits per block.
+				 * Must be consistent with chunks_per_block.
+				 */
+
+	int n_erased_blocks;
+	int alloc_block;	/* Current block being allocated off */
+	u32 alloc_page;
+	int alloc_block_finder;	/* Used to search for next allocation block */
+
+	/* Object and Tnode memory management */
+	void *allocator;
+	int n_obj;
+	int n_tnodes;
+
+	int n_hardlinks;
+
+	struct yaffs_obj_bucket obj_bucket[YAFFS_NOBJECT_BUCKETS];
+	u32 bucket_finder;
+
+	int n_free_chunks;
+
+	/* Garbage collection control */
+	u32 *gc_cleanup_list;	/* objects to delete at the end of a GC. */
+	u32 n_clean_ups;
+
+	unsigned has_pending_prioritised_gc;	/* We think this device might
+						have pending prioritised gcs */
+	unsigned gc_disable;
+	unsigned gc_block_finder;
+	unsigned gc_dirtiest;
+	unsigned gc_pages_in_use;
+	unsigned gc_not_done;
+	unsigned gc_block;
+	unsigned gc_chunk;
+	unsigned gc_skip;
+
+	/* Special directories */
+	struct yaffs_obj *root_dir;
+	struct yaffs_obj *lost_n_found;
+
+	int buffered_block;	/* Which block is buffered here? */
+	int doing_buffered_block_rewrite;
+
+	struct yaffs_cache *cache;
+	int cache_last_use;
+
+	/* Stuff for background deletion and unlinked files. */
+	struct yaffs_obj *unlinked_dir;	/* Directory where unlinked and deleted
+					 files live. */
+	struct yaffs_obj *del_dir;	/* Directory where deleted objects are
+					sent to disappear. */
+	struct yaffs_obj *unlinked_deletion;	/* Current file being
+							background deleted. */
+	int n_deleted_files;	/* Count of files awaiting deletion; */
+	int n_unlinked_files;	/* Count of unlinked files. */
+	int n_bg_deletions;	/* Count of background deletions. */
+
+	/* Temporary buffer management */
+	struct yaffs_buffer temp_buffer[YAFFS_N_TEMP_BUFFERS];
+	int max_temp;
+	int temp_in_use;
+	int unmanaged_buffer_allocs;
+	int unmanaged_buffer_deallocs;
+
+	/* yaffs2 runtime stuff */
+	unsigned seq_number;	/* Sequence number of currently
+					allocating block */
+	unsigned oldest_dirty_seq;
+	unsigned oldest_dirty_block;
+
+	/* Block refreshing */
+	int refresh_skip;	/* A skip down counter.
+				 * Refresh happens when this gets to zero. */
+
+	/* Dirty directory handling */
+	struct list_head dirty_dirs;	/* List of dirty directories */
+
+	/* Statistcs */
+	u32 n_page_writes;
+	u32 n_page_reads;
+	u32 n_erasures;
+	u32 n_erase_failures;
+	u32 n_gc_copies;
+	u32 all_gcs;
+	u32 passive_gc_count;
+	u32 oldest_dirty_gc_count;
+	u32 n_gc_blocks;
+	u32 bg_gcs;
+	u32 n_retired_writes;
+	u32 n_retired_blocks;
+	u32 n_ecc_fixed;
+	u32 n_ecc_unfixed;
+	u32 n_tags_ecc_fixed;
+	u32 n_tags_ecc_unfixed;
+	u32 n_deletions;
+	u32 n_unmarked_deletions;
+	u32 refresh_count;
+	u32 cache_hits;
+
+};
+
+/* The CheckpointDevice structure holds the device information that changes
+ *at runtime and must be preserved over unmount/mount cycles.
+ */
+struct yaffs_checkpt_dev {
+	int struct_type;
+	int n_erased_blocks;
+	int alloc_block;	/* Current block being allocated off */
+	u32 alloc_page;
+	int n_free_chunks;
+
+	int n_deleted_files;	/* Count of files awaiting deletion; */
+	int n_unlinked_files;	/* Count of unlinked files. */
+	int n_bg_deletions;	/* Count of background deletions. */
+
+	/* yaffs2 runtime stuff */
+	unsigned seq_number;	/* Sequence number of currently
+				 * allocating block */
+
+};
+
+struct yaffs_checkpt_validity {
+	int struct_type;
+	u32 magic;
+	u32 version;
+	u32 head;
+};
+
+struct yaffs_shadow_fixer {
+	int obj_id;
+	int shadowed_id;
+	struct yaffs_shadow_fixer *next;
+};
+
+/* Structure for doing xattr modifications */
+struct yaffs_xattr_mod {
+	int set;		/* If 0 then this is a deletion */
+	const YCHAR *name;
+	const void *data;
+	int size;
+	int flags;
+	int result;
+};
+
+/*----------------------- YAFFS Functions -----------------------*/
+
+int yaffs_guts_initialise(struct yaffs_dev *dev);
+void yaffs_deinitialise(struct yaffs_dev *dev);
+
+int yaffs_get_n_free_chunks(struct yaffs_dev *dev);
+
+int yaffs_rename_obj(struct yaffs_obj *old_dir, const YCHAR * old_name,
+		     struct yaffs_obj *new_dir, const YCHAR * new_name);
+
+int yaffs_unlinker(struct yaffs_obj *dir, const YCHAR * name);
+int yaffs_del_obj(struct yaffs_obj *obj);
+
+int yaffs_get_obj_name(struct yaffs_obj *obj, YCHAR * name, int buffer_size);
+int yaffs_get_obj_length(struct yaffs_obj *obj);
+int yaffs_get_obj_inode(struct yaffs_obj *obj);
+unsigned yaffs_get_obj_type(struct yaffs_obj *obj);
+int yaffs_get_obj_link_count(struct yaffs_obj *obj);
+
+/* File operations */
+int yaffs_file_rd(struct yaffs_obj *obj, u8 * buffer, loff_t offset,
+		  int n_bytes);
+int yaffs_wr_file(struct yaffs_obj *obj, const u8 * buffer, loff_t offset,
+		  int n_bytes, int write_trhrough);
+int yaffs_resize_file(struct yaffs_obj *obj, loff_t new_size);
+
+struct yaffs_obj *yaffs_create_file(struct yaffs_obj *parent,
+				    const YCHAR *name, u32 mode, u32 uid,
+				    u32 gid);
+
+int yaffs_flush_file(struct yaffs_obj *obj, int update_time, int data_sync);
+
+/* Flushing and checkpointing */
+void yaffs_flush_whole_cache(struct yaffs_dev *dev);
+
+int yaffs_checkpoint_save(struct yaffs_dev *dev);
+int yaffs_checkpoint_restore(struct yaffs_dev *dev);
+
+/* Directory operations */
+struct yaffs_obj *yaffs_create_dir(struct yaffs_obj *parent, const YCHAR *name,
+				   u32 mode, u32 uid, u32 gid);
+struct yaffs_obj *yaffs_find_by_name(struct yaffs_obj *the_dir,
+				     const YCHAR *name);
+struct yaffs_obj *yaffs_find_by_number(struct yaffs_dev *dev, u32 number);
+
+/* Link operations */
+struct yaffs_obj *yaffs_link_obj(struct yaffs_obj *parent, const YCHAR *name,
+				 struct yaffs_obj *equiv_obj);
+
+struct yaffs_obj *yaffs_get_equivalent_obj(struct yaffs_obj *obj);
+
+/* Symlink operations */
+struct yaffs_obj *yaffs_create_symlink(struct yaffs_obj *parent,
+				       const YCHAR *name, u32 mode, u32 uid,
+				       u32 gid, const YCHAR *alias);
+YCHAR *yaffs_get_symlink_alias(struct yaffs_obj *obj);
+
+/* Special inodes (fifos, sockets and devices) */
+struct yaffs_obj *yaffs_create_special(struct yaffs_obj *parent,
+				       const YCHAR *name, u32 mode, u32 uid,
+				       u32 gid, u32 rdev);
+
+int yaffs_set_xattrib(struct yaffs_obj *obj, const YCHAR *name,
+		      const void *value, int size, int flags);
+int yaffs_get_xattrib(struct yaffs_obj *obj, const YCHAR *name, void *value,
+		      int size);
+int yaffs_list_xattrib(struct yaffs_obj *obj, char *buffer, int size);
+int yaffs_remove_xattrib(struct yaffs_obj *obj, const YCHAR *name);
+
+/* Special directories */
+struct yaffs_obj *yaffs_root(struct yaffs_dev *dev);
+struct yaffs_obj *yaffs_lost_n_found(struct yaffs_dev *dev);
+
+void yaffs_handle_defered_free(struct yaffs_obj *obj);
+
+void yaffs_update_dirty_dirs(struct yaffs_dev *dev);
+
+int yaffs_bg_gc(struct yaffs_dev *dev, unsigned urgency);
+
+/* Debug dump  */
+int yaffs_dump_obj(struct yaffs_obj *obj);
+
+void yaffs_guts_test(struct yaffs_dev *dev);
+
+/* A few useful functions to be used within the core files*/
+void yaffs_chunk_del(struct yaffs_dev *dev, int chunk_id, int mark_flash,
+		     int lyn);
+int yaffs_check_ff(u8 *buffer, int n_bytes);
+void yaffs_handle_chunk_error(struct yaffs_dev *dev,
+			      struct yaffs_block_info *bi);
+
+u8 *yaffs_get_temp_buffer(struct yaffs_dev *dev, int line_no);
+void yaffs_release_temp_buffer(struct yaffs_dev *dev, u8 *buffer, int line_no);
+
+struct yaffs_obj *yaffs_find_or_create_by_number(struct yaffs_dev *dev,
+						 int number,
+						 enum yaffs_obj_type type);
+int yaffs_put_chunk_in_file(struct yaffs_obj *in, int inode_chunk,
+			    int nand_chunk, int in_scan);
+void yaffs_set_obj_name(struct yaffs_obj *obj, const YCHAR *name);
+void yaffs_set_obj_name_from_oh(struct yaffs_obj *obj,
+				const struct yaffs_obj_hdr *oh);
+void yaffs_add_obj_to_dir(struct yaffs_obj *directory, struct yaffs_obj *obj);
+YCHAR *yaffs_clone_str(const YCHAR *str);
+void yaffs_link_fixup(struct yaffs_dev *dev, struct yaffs_obj *hard_list);
+void yaffs_block_became_dirty(struct yaffs_dev *dev, int block_no);
+int yaffs_update_oh(struct yaffs_obj *in, const YCHAR *name,
+		    int force, int is_shrink, int shadows,
+		    struct yaffs_xattr_mod *xop);
+void yaffs_handle_shadowed_obj(struct yaffs_dev *dev, int obj_id,
+			       int backward_scanning);
+int yaffs_check_alloc_available(struct yaffs_dev *dev, int n_chunks);
+struct yaffs_tnode *yaffs_get_tnode(struct yaffs_dev *dev);
+struct yaffs_tnode *yaffs_add_find_tnode_0(struct yaffs_dev *dev,
+					   struct yaffs_file_var *file_struct,
+					   u32 chunk_id,
+					   struct yaffs_tnode *passed_tn);
+
+int yaffs_do_file_wr(struct yaffs_obj *in, const u8 *buffer, loff_t offset,
+		     int n_bytes, int write_trhrough);
+void yaffs_resize_file_down(struct yaffs_obj *obj, loff_t new_size);
+void yaffs_skip_rest_of_block(struct yaffs_dev *dev);
+
+int yaffs_count_free_chunks(struct yaffs_dev *dev);
+
+struct yaffs_tnode *yaffs_find_tnode_0(struct yaffs_dev *dev,
+				       struct yaffs_file_var *file_struct,
+				       u32 chunk_id);
+
+u32 yaffs_get_group_base(struct yaffs_dev *dev, struct yaffs_tnode *tn,
+			 unsigned pos);
+
+int yaffs_is_non_empty_dir(struct yaffs_obj *obj);
+#endif
-- 
1.7.1

[PATCH 09/10] Add yaffs2 file system: Linux glue code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_linux.h |   41 +
 fs/yaffs2/yaffs_vfs.c   | 2756 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yportenv.h    |   70 ++
 3 files changed, 2867 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_linux.h
 create mode 100644 fs/yaffs2/yaffs_vfs.c
 create mode 100644 fs/yaffs2/yportenv.h

diff --git a/fs/yaffs2/yaffs_linux.h b/fs/yaffs2/yaffs_linux.h
new file mode 100644
index 0000000..8c2f399
--- /dev/null
+++ b/fs/yaffs2/yaffs_linux.h
@@ -0,0 +1,41 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_LINUX_H__
+#define __YAFFS_LINUX_H__
+
+#include "yportenv.h"
+
+struct yaffs_linux_context {
+	struct list_head context_list;	/* List of these we have mounted */
+	struct yaffs_dev *dev;
+	struct super_block *super;
+	struct task_struct *bg_thread;	/* Background thread for this device */
+	int bg_running;
+	struct mutex gross_lock;	/* Gross locking mutex*/
+	u8 *spare_buffer;	/* For mtdif2 use. Don't know the buffer size
+				 * at compile time so we have to allocate it.
+				 */
+	struct list_head search_contexts;
+	void (*put_super_fn) (struct super_block *sb);
+
+	struct task_struct *readdir_process;
+	unsigned mount_id;
+};
+
+#define yaffs_dev_to_lc(dev) ((struct yaffs_linux_context *)((dev)->os_context))
+#define yaffs_dev_to_mtd(dev) ((struct mtd_info *)((dev)->driver_context))
+
+#endif
diff --git a/fs/yaffs2/yaffs_vfs.c b/fs/yaffs2/yaffs_vfs.c
new file mode 100644
index 0000000..4a0ec0a
--- /dev/null
+++ b/fs/yaffs2/yaffs_vfs.c
@@ -0,0 +1,2756 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ * Acknowledgements:
+ * Luc van OostenRyck for numerous patches.
+ * Nick Bane for numerous patches.
+ * Nick Bane for 2.5/2.6 integration.
+ * Andras Toth for mknod rdev issue.
+ * Michael Fischer for finding the problem with inode inconsistency.
+ * Some code bodily lifted from JFFS
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ *
+ * This is the file system front-end to YAFFS that hooks it up to
+ * the VFS.
+ *
+ * Special notes:
+ * >> 2.4: sb->u.generic_sbp points to the struct yaffs_dev associated with
+ *         this superblock
+ * >> 2.6: sb->s_fs_info  points to the struct yaffs_dev associated with this
+ *         superblock
+ * >> inode->u.generic_ip points to the associated struct yaffs_obj.
+ */
+
+/*
+ * NB There are two variants of Linux VFS glue code. This variant supports
+ * a single version and should not include any multi-version code.
+ */
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/proc_fs.h>
+#include <linux/smp_lock.h>
+#include <linux/pagemap.h>
+#include <linux/mtd/mtd.h>
+#include <linux/interrupt.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/namei.h>
+#include <linux/exportfs.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+#include <linux/freezer.h>
+#include <asm/div64.h>
+#include <linux/statfs.h>
+#include <linux/uaccess.h>
+#include <linux/mtd/mtd.h>
+
+#include "yportenv.h"
+#include "yaffs_trace.h"
+#include "yaffs_guts.h"
+#include "yaffs_attribs.h"
+#include "yaffs_linux.h"
+#include "yaffs_mtdif.h"
+#include "yaffs_mtdif1.h"
+#include "yaffs_mtdif2.h"
+
+unsigned int yaffs_trace_mask = YAFFS_TRACE_BAD_BLOCKS | YAFFS_TRACE_ALWAYS;
+unsigned int yaffs_wr_attempts = YAFFS_WR_ATTEMPTS;
+unsigned int yaffs_auto_checkpoint = 1;
+unsigned int yaffs_gc_control = 1;
+unsigned int yaffs_bg_enable = 1;
+
+/* Module Parameters */
+module_param(yaffs_trace_mask, uint, 0644);
+module_param(yaffs_wr_attempts, uint, 0644);
+module_param(yaffs_auto_checkpoint, uint, 0644);
+module_param(yaffs_gc_control, uint, 0644);
+module_param(yaffs_bg_enable, uint, 0644);
+
+#define yaffs_devname(sb, buf)	bdevname(sb->s_bdev, buf)
+
+static uint32_t YCALCBLOCKS(uint64_t partition_size, uint32_t block_size)
+{
+	uint64_t result = partition_size;
+
+	do_div(result, block_size);
+	return (uint32_t) result;
+}
+
+#define yaffs_inode_to_obj_lv(iptr) ((iptr)->i_private)
+#define yaffs_inode_to_obj(iptr)\
+	((struct yaffs_obj *)(yaffs_inode_to_obj_lv(iptr)))
+#define yaffs_dentry_to_obj(dptr) yaffs_inode_to_obj((dptr)->d_inode)
+#define yaffs_super_to_dev(sb)	((struct yaffs_dev *)sb->s_fs_info)
+
+#define update_dir_time(dir) do {\
+			(dir)->i_ctime = (dir)->i_mtime = CURRENT_TIME; \
+		} while (0)
+
+
+static unsigned yaffs_gc_control_callback(struct yaffs_dev *dev)
+{
+	return yaffs_gc_control;
+}
+
+static void yaffs_gross_lock(struct yaffs_dev *dev)
+{
+	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locking %p", current);
+	mutex_lock(&(yaffs_dev_to_lc(dev)->gross_lock));
+	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locked %p", current);
+}
+
+static void yaffs_gross_unlock(struct yaffs_dev *dev)
+{
+	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs unlocking %p", current);
+	mutex_unlock(&(yaffs_dev_to_lc(dev)->gross_lock));
+}
+
+static void yaffs_fill_inode_from_obj(struct inode *inode,
+				      struct yaffs_obj *obj);
+
+static struct inode *yaffs_iget(struct super_block *sb, unsigned long ino)
+{
+	struct inode *inode;
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_iget for %lu", ino);
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+
+	/* NB This is called as a side effect of other functions, but
+	 * we had to release the lock to prevent deadlocks, so
+	 * need to lock again.
+	 */
+
+	yaffs_gross_lock(dev);
+
+	obj = yaffs_find_by_number(dev, inode->i_ino);
+	yaffs_fill_inode_from_obj(inode, obj);
+
+	yaffs_gross_unlock(dev);
+
+	unlock_new_inode(inode);
+	return inode;
+}
+
+struct inode *yaffs_get_inode(struct super_block *sb, int mode, int dev,
+			      struct yaffs_obj *obj)
+{
+	struct inode *inode;
+
+	if (!sb) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_get_inode for NULL super_block!!");
+		return NULL;
+
+	}
+
+	if (!obj) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_get_inode for NULL object!!");
+		return NULL;
+
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_get_inode for object %d",
+		obj->obj_id);
+
+	inode = yaffs_iget(sb, obj->obj_id);
+	if (IS_ERR(inode))
+		return NULL;
+
+	/* NB Side effect: iget calls back to yaffs_read_inode(). */
+	/* iget also increments the inode's i_count */
+	/* NB You can't be holding gross_lock or deadlock will happen! */
+
+	return inode;
+}
+
+static int yaffs_mknod(struct inode *dir, struct dentry *dentry, int mode,
+		       dev_t rdev)
+{
+	struct inode *inode;
+	struct yaffs_obj *obj = NULL;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *parent = yaffs_inode_to_obj(dir);
+	int error = -ENOSPC;
+	uid_t uid = current->cred->fsuid;
+	gid_t gid =
+	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
+
+	if ((dir->i_mode & S_ISGID) && S_ISDIR(mode))
+		mode |= S_ISGID;
+
+	if (parent) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_mknod: parent object %d type %d",
+			parent->obj_id, parent->variant_type);
+	} else {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_mknod: could not get parent object");
+		return -EPERM;
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_mknod: making oject for %s, mode %x dev %x",
+		dentry->d_name.name, mode, rdev);
+
+	dev = parent->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	switch (mode & S_IFMT) {
+	default:
+		/* Special (socket, fifo, device...) */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making special");
+		obj =
+		    yaffs_create_special(parent, dentry->d_name.name, mode, uid,
+					 gid, old_encode_dev(rdev));
+		break;
+	case S_IFREG:		/* file          */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making file");
+		obj = yaffs_create_file(parent, dentry->d_name.name, mode, uid,
+					gid);
+		break;
+	case S_IFDIR:		/* directory */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making directory");
+		obj = yaffs_create_dir(parent, dentry->d_name.name, mode,
+				       uid, gid);
+		break;
+	case S_IFLNK:		/* symlink */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making symlink");
+		obj = NULL;	/* Do we ever get here? */
+		break;
+	}
+
+	/* Can not call yaffs_get_inode() with gross lock held */
+	yaffs_gross_unlock(dev);
+
+	if (obj) {
+		inode = yaffs_get_inode(dir->i_sb, mode, rdev, obj);
+		d_instantiate(dentry, inode);
+		update_dir_time(dir);
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_mknod created object %d count = %d",
+			obj->obj_id, atomic_read(&inode->i_count));
+		error = 0;
+		yaffs_fill_inode_from_obj(dir, parent);
+	} else {
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod failed making object");
+		error = -ENOMEM;
+	}
+
+	return error;
+}
+
+static int yaffs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+	return yaffs_mknod(dir, dentry, mode | S_IFDIR, 0);
+}
+
+static int yaffs_create(struct inode *dir, struct dentry *dentry, int mode,
+			struct nameidata *n)
+{
+	return yaffs_mknod(dir, dentry, mode | S_IFREG, 0);
+}
+
+static int yaffs_link(struct dentry *old_dentry, struct inode *dir,
+		      struct dentry *dentry)
+{
+	struct inode *inode = old_dentry->d_inode;
+	struct yaffs_obj *obj = NULL;
+	struct yaffs_obj *link = NULL;
+	struct yaffs_dev *dev;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_link");
+
+	obj = yaffs_inode_to_obj(inode);
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	if (!S_ISDIR(inode->i_mode))	/* Don't link directories */
+		link =
+		    yaffs_link_obj(yaffs_inode_to_obj(dir), dentry->d_name.name,
+				   obj);
+
+	if (link) {
+		old_dentry->d_inode->i_nlink = yaffs_get_obj_link_count(obj);
+		d_instantiate(dentry, old_dentry->d_inode);
+		atomic_inc(&old_dentry->d_inode->i_count);
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_link link count %d i_count %d",
+			old_dentry->d_inode->i_nlink,
+			atomic_read(&old_dentry->d_inode->i_count));
+	}
+
+	yaffs_gross_unlock(dev);
+
+	if (link) {
+		update_dir_time(dir);
+		return 0;
+	}
+
+	return -EPERM;
+}
+
+static int yaffs_symlink(struct inode *dir, struct dentry *dentry,
+			 const char *symname)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	uid_t uid = current->cred->fsuid;
+	gid_t gid =
+	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_symlink");
+
+	dev = yaffs_inode_to_obj(dir)->my_dev;
+	yaffs_gross_lock(dev);
+	obj = yaffs_create_symlink(yaffs_inode_to_obj(dir), dentry->d_name.name,
+				   S_IFLNK | S_IRWXUGO, uid, gid, symname);
+	yaffs_gross_unlock(dev);
+
+	if (obj) {
+		struct inode *inode;
+
+		inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
+		d_instantiate(dentry, inode);
+		update_dir_time(dir);
+		yaffs_trace(YAFFS_TRACE_OS, "symlink created OK");
+		return 0;
+	} else {
+		yaffs_trace(YAFFS_TRACE_OS, "symlink not created");
+	}
+
+	return -ENOMEM;
+}
+
+static struct dentry *yaffs_lookup(struct inode *dir, struct dentry *dentry,
+				   struct nameidata *n)
+{
+	struct yaffs_obj *obj;
+	struct inode *inode = NULL;
+	struct yaffs_dev *dev = yaffs_inode_to_obj(dir)->my_dev;
+
+	if (current != yaffs_dev_to_lc(dev)->readdir_process)
+		yaffs_gross_lock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_lookup for %d:%s",
+		yaffs_inode_to_obj(dir)->obj_id, dentry->d_name.name);
+
+	obj = yaffs_find_by_name(yaffs_inode_to_obj(dir), dentry->d_name.name);
+
+	obj = yaffs_get_equivalent_obj(obj);	/* in case it was a hardlink */
+
+	/* Can't hold gross lock when calling yaffs_get_inode() */
+	if (current != yaffs_dev_to_lc(dev)->readdir_process)
+		yaffs_gross_unlock(dev);
+
+	if (obj) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_lookup found %d", obj->obj_id);
+
+		inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
+
+		if (inode) {
+			yaffs_trace(YAFFS_TRACE_OS, "yaffs_loookup dentry");
+			d_add(dentry, inode);
+			/* return dentry; */
+			return NULL;
+		}
+
+	} else {
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_lookup not found");
+
+	}
+
+	d_add(dentry, inode);
+
+	return NULL;
+}
+
+static int yaffs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	int ret_val;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_unlink %d:%s",
+		(int)(dir->i_ino), dentry->d_name.name);
+	obj = yaffs_inode_to_obj(dir);
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	ret_val = yaffs_unlinker(obj, dentry->d_name.name);
+
+	if (ret_val == YAFFS_OK) {
+		dentry->d_inode->i_nlink--;
+		dir->i_version++;
+		yaffs_gross_unlock(dev);
+		mark_inode_dirty(dentry->d_inode);
+		update_dir_time(dir);
+		return 0;
+	}
+	yaffs_gross_unlock(dev);
+	return -ENOTEMPTY;
+}
+
+static int yaffs_sync_object(struct file *file, int datasync)
+{
+
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	struct dentry *dentry = file->f_path.dentry;
+
+	obj = yaffs_dentry_to_obj(dentry);
+
+	dev = obj->my_dev;
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC, "yaffs_sync_object");
+	yaffs_gross_lock(dev);
+	yaffs_flush_file(obj, 1, datasync);
+	yaffs_gross_unlock(dev);
+	return 0;
+}
+/*
+ * The VFS layer already does all the dentry stuff for rename.
+ *
+ * NB: POSIX says you can rename an object over an old object of the same name
+ */
+static int yaffs_rename(struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir, struct dentry *new_dentry)
+{
+	struct yaffs_dev *dev;
+	int ret_val = YAFFS_FAIL;
+	struct yaffs_obj *target;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_rename");
+	dev = yaffs_inode_to_obj(old_dir)->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	/* Check if the target is an existing directory that is not empty. */
+	target = yaffs_find_by_name(yaffs_inode_to_obj(new_dir),
+				    new_dentry->d_name.name);
+
+	if (target && target->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY &&
+	    !list_empty(&target->variant.dir_variant.children)) {
+
+		yaffs_trace(YAFFS_TRACE_OS, "target is non-empty dir");
+
+		ret_val = YAFFS_FAIL;
+	} else {
+		/* Now does unlinking internally using shadowing mechanism */
+		yaffs_trace(YAFFS_TRACE_OS, "calling yaffs_rename_obj");
+
+		ret_val = yaffs_rename_obj(yaffs_inode_to_obj(old_dir),
+					   old_dentry->d_name.name,
+					   yaffs_inode_to_obj(new_dir),
+					   new_dentry->d_name.name);
+	}
+	yaffs_gross_unlock(dev);
+
+	if (ret_val == YAFFS_OK) {
+		if (target) {
+			new_dentry->d_inode->i_nlink--;
+			mark_inode_dirty(new_dentry->d_inode);
+		}
+
+		update_dir_time(old_dir);
+		if (old_dir != new_dir)
+			update_dir_time(new_dir);
+		return 0;
+	} else {
+		return -ENOTEMPTY;
+	}
+}
+
+static int yaffs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = dentry->d_inode;
+	int error = 0;
+	struct yaffs_dev *dev;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_setattr of object %d",
+		yaffs_inode_to_obj(inode)->obj_id);
+
+	/* Fail if a requested resize >= 2GB */
+	if (attr->ia_valid & ATTR_SIZE && (attr->ia_size >> 31))
+		error = -EINVAL;
+
+	if (error == 0)
+		error = inode_change_ok(inode, attr);
+	if (error == 0) {
+		int result;
+		if (!error) {
+			setattr_copy(inode, attr);
+			yaffs_trace(YAFFS_TRACE_OS, "inode_setattr called");
+			if (attr->ia_valid & ATTR_SIZE) {
+				truncate_setsize(inode, attr->ia_size);
+				inode->i_blocks = (inode->i_size + 511) >> 9;
+			}
+		}
+		dev = yaffs_inode_to_obj(inode)->my_dev;
+		if (attr->ia_valid & ATTR_SIZE) {
+			yaffs_trace(YAFFS_TRACE_OS, "resize to %d(%x)",
+					   (int)(attr->ia_size),
+					   (int)(attr->ia_size));
+		}
+		yaffs_gross_lock(dev);
+		result = yaffs_set_attribs(yaffs_inode_to_obj(inode), attr);
+		if (result == YAFFS_OK)
+			error = 0;
+		else
+			error = -EPERM;
+		yaffs_gross_unlock(dev);
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setattr done returning %d", error);
+
+	return error;
+}
+
+#ifdef CONFIG_YAFFS_XATTR
+static int yaffs_setxattr(struct dentry *dentry, const char *name,
+		   const void *value, size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	int error = 0;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr of object %d", obj->obj_id);
+
+	if (error == 0) {
+		int result;
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		result = yaffs_set_xattrib(obj, name, value, size, flags);
+		if (result == YAFFS_OK)
+			error = 0;
+		else if (result < 0)
+			error = result;
+		yaffs_gross_unlock(dev);
+	}
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr done returning %d", error);
+
+	return error;
+}
+
+static ssize_t yaffs_getxattr(struct dentry *dentry, const char *name,
+				void *buff, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error = 0;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_getxattr \"%s\" from object %d",
+		name, obj->obj_id);
+
+	if (error == 0) {
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		error = yaffs_get_xattrib(obj, name, buff, size);
+		yaffs_gross_unlock(dev);
+	}
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_getxattr done returning %d", error);
+
+	return error;
+}
+
+static int yaffs_removexattr(struct dentry *dentry, const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	int error = 0;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_removexattr of object %d", obj->obj_id);
+
+	if (error == 0) {
+		int result;
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		result = yaffs_remove_xattrib(obj, name);
+		if (result == YAFFS_OK)
+			error = 0;
+		else if (result < 0)
+			error = result;
+		yaffs_gross_unlock(dev);
+	}
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_removexattr done returning %d", error);
+
+	return error;
+}
+
+static ssize_t yaffs_listxattr(struct dentry *dentry, char *buff, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error = 0;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_listxattr of object %d", obj->obj_id);
+
+	if (error == 0) {
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		error = yaffs_list_xattrib(obj, buff, size);
+		yaffs_gross_unlock(dev);
+	}
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_listxattr done returning %d", error);
+
+	return error;
+}
+
+#endif
+
+static const struct inode_operations yaffs_dir_inode_operations = {
+	.create = yaffs_create,
+	.lookup = yaffs_lookup,
+	.link = yaffs_link,
+	.unlink = yaffs_unlink,
+	.symlink = yaffs_symlink,
+	.mkdir = yaffs_mkdir,
+	.rmdir = yaffs_unlink,
+	.mknod = yaffs_mknod,
+	.rename = yaffs_rename,
+	.setattr = yaffs_setattr,
+#ifdef CONFIG_YAFFS_XATTR
+	.setxattr = yaffs_setxattr,
+	.getxattr = yaffs_getxattr,
+	.listxattr = yaffs_listxattr,
+	.removexattr = yaffs_removexattr,
+#endif
+};
+/*-----------------------------------------------------------------*/
+/* Directory search context allows us to unlock access to yaffs during
+ * filldir without causing problems with the directory being modified.
+ * This is similar to the tried and tested mechanism used in yaffs direct.
+ *
+ * A search context iterates along a doubly linked list of siblings in the
+ * directory. If the iterating object is deleted then this would corrupt
+ * the list iteration, likely causing a crash. The search context avoids
+ * this by using the remove_obj_fn to move the search context to the
+ * next object before the object is deleted.
+ *
+ * Many readdirs (and thus seach conexts) may be alive simulateously so
+ * each struct yaffs_dev has a list of these.
+ *
+ * A seach context lives for the duration of a readdir.
+ *
+ * All these functions must be called while yaffs is locked.
+ */
+
+struct yaffs_search_context {
+	struct yaffs_dev *dev;
+	struct yaffs_obj *dir_obj;
+	struct yaffs_obj *next_return;
+	struct list_head others;
+};
+
+/*
+ * yaffs_new_search() creates a new search context, initialises it and
+ * adds it to the device's search context list.
+ *
+ * Called at start of readdir.
+ */
+static struct yaffs_search_context *yaffs_new_search(struct yaffs_obj *dir)
+{
+	struct yaffs_dev *dev = dir->my_dev;
+	struct yaffs_search_context *sc =
+	    kmalloc(sizeof(struct yaffs_search_context), GFP_NOFS);
+
+	if (sc) {
+		sc->dir_obj = dir;
+		sc->dev = dev;
+		if (list_empty(&sc->dir_obj->variant.dir_variant.children))
+			sc->next_return = NULL;
+		else
+			sc->next_return =
+			    list_entry(dir->variant.dir_variant.children.next,
+				       struct yaffs_obj, siblings);
+		INIT_LIST_HEAD(&sc->others);
+		list_add(&sc->others, &(yaffs_dev_to_lc(dev)->search_contexts));
+	}
+	return sc;
+}
+
+/*
+ * yaffs_search_end() disposes of a search context and cleans up.
+ */
+static void yaffs_search_end(struct yaffs_search_context *sc)
+{
+	if (sc) {
+		list_del(&sc->others);
+		kfree(sc);
+	}
+}
+
+/*
+ * yaffs_search_advance() moves a search context to the next object.
+ * Called when the search iterates or when an object removal causes
+ * the search context to be moved to the next object.
+ */
+static void yaffs_search_advance(struct yaffs_search_context *sc)
+{
+	if (!sc)
+		return;
+
+	if (sc->next_return == NULL ||
+	    list_empty(&sc->dir_obj->variant.dir_variant.children))
+		sc->next_return = NULL;
+	else {
+		struct list_head *next = sc->next_return->siblings.next;
+
+		if (next == &sc->dir_obj->variant.dir_variant.children)
+			sc->next_return = NULL;	/* end of list */
+		else
+			sc->next_return =
+			    list_entry(next, struct yaffs_obj, siblings);
+	}
+}
+
+/*
+ * yaffs_remove_obj_callback() is called when an object is unlinked.
+ * We check open search contexts and advance any which are currently
+ * on the object being iterated.
+ */
+static void yaffs_remove_obj_callback(struct yaffs_obj *obj)
+{
+
+	struct list_head *i;
+	struct yaffs_search_context *sc;
+	struct list_head *search_contexts =
+	    &(yaffs_dev_to_lc(obj->my_dev)->search_contexts);
+
+	/* Iterate through the directory search contexts.
+	 * If any are currently on the object being removed, then advance
+	 * the search context to the next object to prevent a hanging pointer.
+	 */
+	list_for_each(i, search_contexts) {
+		sc = list_entry(i, struct yaffs_search_context, others);
+		if (sc->next_return == obj)
+			yaffs_search_advance(sc);
+	}
+
+}
+
+static int yaffs_readdir(struct file *f, void *dirent, filldir_t filldir)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	struct yaffs_search_context *sc;
+	struct inode *inode = f->f_dentry->d_inode;
+	unsigned long offset, curoffs;
+	struct yaffs_obj *l;
+	int ret_val = 0;
+	char name[YAFFS_MAX_NAME_LENGTH + 1];
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	yaffs_dev_to_lc(dev)->readdir_process = current;
+
+	offset = f->f_pos;
+
+	sc = yaffs_new_search(obj);
+	if (!sc) {
+		ret_val = -ENOMEM;
+		goto out;
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_readdir: starting at %d", (int)offset);
+
+	if (offset == 0) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_readdir: entry . ino %d",
+			(int)inode->i_ino);
+		yaffs_gross_unlock(dev);
+		if (filldir(dirent, ".", 1, offset, inode->i_ino, DT_DIR) < 0) {
+			yaffs_gross_lock(dev);
+			goto out;
+		}
+		yaffs_gross_lock(dev);
+		offset++;
+		f->f_pos++;
+	}
+	if (offset == 1) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_readdir: entry .. ino %d",
+			(int)f->f_dentry->d_parent->d_inode->i_ino);
+		yaffs_gross_unlock(dev);
+		if (filldir(dirent, "..", 2, offset,
+			    f->f_dentry->d_parent->d_inode->i_ino,
+			    DT_DIR) < 0) {
+			yaffs_gross_lock(dev);
+			goto out;
+		}
+		yaffs_gross_lock(dev);
+		offset++;
+		f->f_pos++;
+	}
+
+	curoffs = 1;
+
+	/* If the directory has changed since the open or last call to
+	   readdir, rewind to after the 2 canned entries. */
+	if (f->f_version != inode->i_version) {
+		offset = 2;
+		f->f_pos = offset;
+		f->f_version = inode->i_version;
+	}
+
+	while (sc->next_return) {
+		curoffs++;
+		l = sc->next_return;
+		if (curoffs >= offset) {
+			int this_inode = yaffs_get_obj_inode(l);
+			int this_type = yaffs_get_obj_type(l);
+
+			yaffs_get_obj_name(l, name, YAFFS_MAX_NAME_LENGTH + 1);
+			yaffs_trace(YAFFS_TRACE_OS,
+				"yaffs_readdir: %s inode %d",
+				name, yaffs_get_obj_inode(l));
+
+			yaffs_gross_unlock(dev);
+
+			if (filldir(dirent,
+				    name,
+				    strlen(name),
+				    offset, this_inode, this_type) < 0) {
+				yaffs_gross_lock(dev);
+				goto out;
+			}
+
+			yaffs_gross_lock(dev);
+
+			offset++;
+			f->f_pos++;
+		}
+		yaffs_search_advance(sc);
+	}
+
+out:
+	yaffs_search_end(sc);
+	yaffs_dev_to_lc(dev)->readdir_process = NULL;
+	yaffs_gross_unlock(dev);
+
+	return ret_val;
+}
+
+static const struct file_operations yaffs_dir_operations = {
+	.read = generic_read_dir,
+	.readdir = yaffs_readdir,
+	.fsync = yaffs_sync_object,
+	.llseek = generic_file_llseek,
+};
+
+
+
+static int yaffs_file_flush(struct file *file, fl_owner_t id)
+{
+	struct yaffs_obj *obj = yaffs_dentry_to_obj(file->f_dentry);
+	struct yaffs_dev *dev = obj->my_dev;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_file_flush object %d (%s)",
+		obj->obj_id, obj->dirty ? "dirty" : "clean");
+
+	yaffs_gross_lock(dev);
+
+	yaffs_flush_file(obj, 1, 0);
+
+	yaffs_gross_unlock(dev);
+
+	return 0;
+}
+
+static const struct file_operations yaffs_file_operations = {
+	.read = do_sync_read,
+	.write = do_sync_write,
+	.aio_read = generic_file_aio_read,
+	.aio_write = generic_file_aio_write,
+	.mmap = generic_file_mmap,
+	.flush = yaffs_file_flush,
+	.fsync = yaffs_sync_object,
+	.splice_read = generic_file_splice_read,
+	.splice_write = generic_file_splice_write,
+	.llseek = generic_file_llseek,
+};
+
+
+/* ExportFS support */
+static struct inode *yaffs2_nfs_get_inode(struct super_block *sb, uint64_t ino,
+					  uint32_t generation)
+{
+	return yaffs_iget(sb, ino);
+}
+
+static struct dentry *yaffs2_fh_to_dentry(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
+{
+	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+				    yaffs2_nfs_get_inode);
+}
+
+static struct dentry *yaffs2_fh_to_parent(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
+{
+	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+				    yaffs2_nfs_get_inode);
+}
+
+struct dentry *yaffs2_get_parent(struct dentry *dentry)
+{
+
+	struct super_block *sb = dentry->d_inode->i_sb;
+	struct dentry *parent = ERR_PTR(-ENOENT);
+	struct inode *inode;
+	unsigned long parent_ino;
+	struct yaffs_obj *d_obj;
+	struct yaffs_obj *parent_obj;
+
+	d_obj = yaffs_inode_to_obj(dentry->d_inode);
+
+	if (d_obj) {
+		parent_obj = d_obj->parent;
+		if (parent_obj) {
+			parent_ino = yaffs_get_obj_inode(parent_obj);
+			inode = yaffs_iget(sb, parent_ino);
+
+			if (IS_ERR(inode)) {
+				parent = ERR_CAST(inode);
+			} else {
+				parent = d_obtain_alias(inode);
+				if (!IS_ERR(parent)) {
+					parent = ERR_PTR(-ENOMEM);
+					iput(inode);
+				}
+			}
+		}
+	}
+	return parent;
+}
+
+/* Just declare a zero structure as a NULL value implies
+ * using the default functions of exportfs.
+ */
+
+static struct export_operations yaffs_export_ops = {
+	.fh_to_dentry = yaffs2_fh_to_dentry,
+	.fh_to_parent = yaffs2_fh_to_parent,
+	.get_parent = yaffs2_get_parent,
+};
+
+
+/*-----------------------------------------------------------------*/
+
+static int yaffs_readlink(struct dentry *dentry, char __user * buffer,
+			  int buflen)
+{
+	unsigned char *alias;
+	int ret;
+	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
+
+	yaffs_gross_unlock(dev);
+
+	if (!alias)
+		return -ENOMEM;
+
+	ret = vfs_readlink(dentry, buffer, buflen, alias);
+	kfree(alias);
+	return ret;
+}
+
+static void *yaffs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	unsigned char *alias;
+	void *ret;
+	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
+	yaffs_gross_unlock(dev);
+
+	if (!alias) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	nd_set_link(nd, alias);
+	ret = (void *)alias;
+out:
+	return ret;
+}
+
+void yaffs_put_link(struct dentry *dentry, struct nameidata *nd, void *alias)
+{
+	kfree(alias);
+}
+
+
+static void yaffs_unstitch_obj(struct inode *inode, struct yaffs_obj *obj)
+{
+	/* Clear the association between the inode and
+	 * the struct yaffs_obj.
+	 */
+	obj->my_inode = NULL;
+	yaffs_inode_to_obj_lv(inode) = NULL;
+
+	/* If the object freeing was deferred, then the real
+	 * free happens now.
+	 * This should fix the inode inconsistency problem.
+	 */
+	yaffs_handle_defered_free(obj);
+}
+
+/* yaffs_evict_inode combines into one operation what was previously done in
+ * yaffs_clear_inode() and yaffs_delete_inode()
+ *
+ */
+static void yaffs_evict_inode(struct inode *inode)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	int deleteme = 0;
+
+	obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_evict_inode: ino %d, count %d %s",
+		(int)inode->i_ino,
+		atomic_read(&inode->i_count),
+		obj ? "object exists" : "null object");
+
+	if (!inode->i_nlink && !is_bad_inode(inode))
+		deleteme = 1;
+	truncate_inode_pages(&inode->i_data, 0);
+	end_writeback(inode);
+
+	if (deleteme && obj) {
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		yaffs_del_obj(obj);
+		yaffs_gross_unlock(dev);
+	}
+	if (obj) {
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		yaffs_unstitch_obj(inode, obj);
+		yaffs_gross_unlock(dev);
+	}
+
+}
+
+static void yaffs_touch_super(struct yaffs_dev *dev)
+{
+	struct super_block *sb = yaffs_dev_to_lc(dev)->super;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_touch_super() sb = %p", sb);
+	if (sb)
+		sb->s_dirt = 1;
+}
+
+static int yaffs_readpage_nolock(struct file *f, struct page *pg)
+{
+	/* Lifted from jffs2 */
+
+	struct yaffs_obj *obj;
+	unsigned char *pg_buf;
+	int ret;
+	struct yaffs_dev *dev;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_readpage_nolock at %08x, size %08x",
+		(unsigned)(pg->index << PAGE_CACHE_SHIFT),
+		(unsigned)PAGE_CACHE_SIZE);
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	dev = obj->my_dev;
+
+	BUG_ON(!PageLocked(pg));
+
+	pg_buf = kmap(pg);
+	/* FIXME: Can kmap fail? */
+
+	yaffs_gross_lock(dev);
+
+	ret = yaffs_file_rd(obj, pg_buf,
+			    pg->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE);
+
+	yaffs_gross_unlock(dev);
+
+	if (ret >= 0)
+		ret = 0;
+
+	if (ret) {
+		ClearPageUptodate(pg);
+		SetPageError(pg);
+	} else {
+		SetPageUptodate(pg);
+		ClearPageError(pg);
+	}
+
+	flush_dcache_page(pg);
+	kunmap(pg);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage_nolock done");
+	return ret;
+}
+
+static int yaffs_readpage_unlock(struct file *f, struct page *pg)
+{
+	int ret = yaffs_readpage_nolock(f, pg);
+
+	unlock_page(pg);
+	return ret;
+}
+
+static int yaffs_readpage(struct file *f, struct page *pg)
+{
+	int ret;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage");
+	ret = yaffs_readpage_unlock(f, pg);
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage done");
+	return ret;
+}
+
+/* writepage inspired by/stolen from smbfs */
+
+static int yaffs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct yaffs_dev *dev;
+	struct address_space *mapping = page->mapping;
+	struct inode *inode;
+	unsigned long end_index;
+	char *buffer;
+	struct yaffs_obj *obj;
+	int n_written = 0;
+	unsigned n_bytes;
+	loff_t i_size;
+
+	if (!mapping)
+		BUG();
+	inode = mapping->host;
+	if (!inode)
+		BUG();
+	i_size = i_size_read(inode);
+
+	end_index = i_size >> PAGE_CACHE_SHIFT;
+
+	if (page->index < end_index)
+		n_bytes = PAGE_CACHE_SIZE;
+	else {
+		n_bytes = i_size & (PAGE_CACHE_SIZE - 1);
+
+		if (page->index > end_index || !n_bytes) {
+			yaffs_trace(YAFFS_TRACE_OS,
+				"yaffs_writepage at %08x, inode size = %08x!!!",
+				(unsigned)(page->index << PAGE_CACHE_SHIFT),
+				(unsigned)inode->i_size);
+			yaffs_trace(YAFFS_TRACE_OS,
+			  "                -> don't care!!");
+
+			zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+			set_page_writeback(page);
+			unlock_page(page);
+			end_page_writeback(page);
+			return 0;
+		}
+	}
+
+	if (n_bytes != PAGE_CACHE_SIZE)
+		zero_user_segment(page, n_bytes, PAGE_CACHE_SIZE);
+
+	get_page(page);
+
+	buffer = kmap(page);
+
+	obj = yaffs_inode_to_obj(inode);
+	dev = obj->my_dev;
+	yaffs_gross_lock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_writepage at %08x, size %08x",
+		(unsigned)(page->index << PAGE_CACHE_SHIFT), n_bytes);
+	yaffs_trace(YAFFS_TRACE_OS,
+		"writepag0: obj = %05x, ino = %05x",
+		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
+
+	n_written = yaffs_wr_file(obj, buffer,
+				  page->index << PAGE_CACHE_SHIFT, n_bytes, 0);
+
+	yaffs_touch_super(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"writepag1: obj = %05x, ino = %05x",
+		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
+
+	yaffs_gross_unlock(dev);
+
+	kunmap(page);
+	set_page_writeback(page);
+	unlock_page(page);
+	end_page_writeback(page);
+	put_page(page);
+
+	return (n_written == n_bytes) ? 0 : -ENOSPC;
+}
+
+/* Space holding and freeing is done to ensure we have space available for
+ * write_begin/end.
+ * For now we just assume few parallel writes and check against a small
+ * number.
+ * Todo: need to do this with a counter to handle parallel reads better
+ */
+
+static ssize_t yaffs_hold_space(struct file *f)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	int n_free_chunks;
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	n_free_chunks = yaffs_get_n_free_chunks(dev);
+
+	yaffs_gross_unlock(dev);
+
+	return (n_free_chunks > 20) ? 1 : 0;
+}
+
+static void yaffs_release_space(struct file *f)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	yaffs_gross_unlock(dev);
+}
+
+static int yaffs_write_begin(struct file *filp, struct address_space *mapping,
+			     loff_t pos, unsigned len, unsigned flags,
+			     struct page **pagep, void **fsdata)
+{
+	struct page *pg = NULL;
+	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+	int ret = 0;
+	int space_held = 0;
+
+	/* Get a page */
+	pg = grab_cache_page_write_begin(mapping, index, flags);
+
+	*pagep = pg;
+	if (!pg) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	yaffs_trace(YAFFS_TRACE_OS,
+		"start yaffs_write_begin index %d(%x) uptodate %d",
+		(int)index, (int)index, PageUptodate(pg) ? 1 : 0);
+
+	/* Get fs space */
+	space_held = yaffs_hold_space(filp);
+
+	if (!space_held) {
+		ret = -ENOSPC;
+		goto out;
+	}
+
+	/* Update page if required */
+
+	if (!PageUptodate(pg))
+		ret = yaffs_readpage_nolock(filp, pg);
+
+	if (ret)
+		goto out;
+
+	/* Happy path return */
+	yaffs_trace(YAFFS_TRACE_OS, "end yaffs_write_begin - ok");
+
+	return 0;
+
+out:
+	yaffs_trace(YAFFS_TRACE_OS,
+		"end yaffs_write_begin fail returning %d", ret);
+	if (space_held)
+		yaffs_release_space(filp);
+	if (pg) {
+		unlock_page(pg);
+		page_cache_release(pg);
+	}
+	return ret;
+}
+
+static ssize_t yaffs_file_write(struct file *f, const char *buf, size_t n,
+				loff_t *pos)
+{
+	struct yaffs_obj *obj;
+	int n_written, ipos;
+	struct inode *inode;
+	struct yaffs_dev *dev;
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	if (!obj) {
+		/* This should not happen */
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_file_write: hey obj is null!");
+		return -EINVAL;
+	}
+
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	inode = f->f_dentry->d_inode;
+
+	if (!S_ISBLK(inode->i_mode) && f->f_flags & O_APPEND)
+		ipos = inode->i_size;
+	else
+		ipos = *pos;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_file_write about to write writing %u(%x) bytes to object %d at %d(%x)",
+		(unsigned)n, (unsigned)n, obj->obj_id, ipos, ipos);
+
+	n_written = yaffs_wr_file(obj, buf, ipos, n, 0);
+
+	yaffs_touch_super(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_file_write: %d(%x) bytes written",
+		(unsigned)n, (unsigned)n);
+
+	if (n_written > 0) {
+		ipos += n_written;
+		*pos = ipos;
+		if (ipos > inode->i_size) {
+			inode->i_size = ipos;
+			inode->i_blocks = (ipos + 511) >> 9;
+
+			yaffs_trace(YAFFS_TRACE_OS,
+				"yaffs_file_write size updated to %d bytes, %d blocks",
+				ipos, (int)(inode->i_blocks));
+		}
+	}
+	yaffs_gross_unlock(dev);
+	return (n_written == 0) && (n > 0) ? -ENOSPC : n_written;
+}
+
+static int yaffs_write_end(struct file *filp, struct address_space *mapping,
+			   loff_t pos, unsigned len, unsigned copied,
+			   struct page *pg, void *fsdadata)
+{
+	int ret = 0;
+	void *addr, *kva;
+	uint32_t offset_into_page = pos & (PAGE_CACHE_SIZE - 1);
+
+	kva = kmap(pg);
+	addr = kva + offset_into_page;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_write_end addr %p pos %x n_bytes %d",
+		addr, (unsigned)pos, copied);
+
+	ret = yaffs_file_write(filp, addr, copied, &pos);
+
+	if (ret != copied) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_write_end not same size ret %d  copied %d",
+			ret, copied);
+		SetPageError(pg);
+	}
+
+	kunmap(pg);
+
+	yaffs_release_space(filp);
+	unlock_page(pg);
+	page_cache_release(pg);
+	return ret;
+}
+
+static int yaffs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
+	struct super_block *sb = dentry->d_sb;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_statfs");
+
+	yaffs_gross_lock(dev);
+
+	buf->f_type = YAFFS_MAGIC;
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_namelen = 255;
+
+	if (dev->data_bytes_per_chunk & (dev->data_bytes_per_chunk - 1)) {
+		/* Do this if chunk size is not a power of 2 */
+
+		uint64_t bytes_in_dev;
+		uint64_t bytes_free;
+
+		bytes_in_dev =
+		    ((uint64_t)
+		     ((dev->param.end_block - dev->param.start_block +
+		       1))) * ((uint64_t) (dev->param.chunks_per_block *
+					   dev->data_bytes_per_chunk));
+
+		do_div(bytes_in_dev, sb->s_blocksize);
+			/* bytes_in_dev becomes the number of blocks */
+		buf->f_blocks = bytes_in_dev;
+
+		bytes_free = ((uint64_t) (yaffs_get_n_free_chunks(dev))) *
+		    ((uint64_t) (dev->data_bytes_per_chunk));
+
+		do_div(bytes_free, sb->s_blocksize);
+
+		buf->f_bfree = bytes_free;
+
+	} else if (sb->s_blocksize > dev->data_bytes_per_chunk) {
+
+		buf->f_blocks =
+		    (dev->param.end_block - dev->param.start_block + 1) *
+		    dev->param.chunks_per_block /
+		    (sb->s_blocksize / dev->data_bytes_per_chunk);
+		buf->f_bfree =
+		    yaffs_get_n_free_chunks(dev) /
+		    (sb->s_blocksize / dev->data_bytes_per_chunk);
+	} else {
+		buf->f_blocks =
+		    (dev->param.end_block - dev->param.start_block + 1) *
+		    dev->param.chunks_per_block *
+		    (dev->data_bytes_per_chunk / sb->s_blocksize);
+
+		buf->f_bfree =
+		    yaffs_get_n_free_chunks(dev) *
+		    (dev->data_bytes_per_chunk / sb->s_blocksize);
+	}
+
+	buf->f_files = 0;
+	buf->f_ffree = 0;
+	buf->f_bavail = buf->f_bfree;
+
+	yaffs_gross_unlock(dev);
+	return 0;
+}
+
+static void yaffs_flush_inodes(struct super_block *sb)
+{
+	struct inode *iptr;
+	struct yaffs_obj *obj;
+
+	list_for_each_entry(iptr, &sb->s_inodes, i_sb_list) {
+		obj = yaffs_inode_to_obj(iptr);
+		if (obj) {
+			yaffs_trace(YAFFS_TRACE_OS,
+				"flushing obj %d", obj->obj_id);
+			yaffs_flush_file(obj, 1, 0);
+		}
+	}
+}
+
+static void yaffs_flush_super(struct super_block *sb, int do_checkpoint)
+{
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+
+	if (!dev)
+		return;
+
+	yaffs_flush_inodes(sb);
+	yaffs_update_dirty_dirs(dev);
+	yaffs_flush_whole_cache(dev);
+	if (do_checkpoint)
+		yaffs_checkpoint_save(dev);
+}
+
+static unsigned yaffs_bg_gc_urgency(struct yaffs_dev *dev)
+{
+	unsigned erased_chunks =
+	    dev->n_erased_blocks * dev->param.chunks_per_block;
+	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
+	unsigned scattered = 0;	/* Free chunks not in an erased block */
+
+	if (erased_chunks < dev->n_free_chunks)
+		scattered = (dev->n_free_chunks - erased_chunks);
+
+	if (!context->bg_running)
+		return 0;
+	else if (scattered < (dev->param.chunks_per_block * 2))
+		return 0;
+	else if (erased_chunks > dev->n_free_chunks / 2)
+		return 0;
+	else if (erased_chunks > dev->n_free_chunks / 4)
+		return 1;
+	else
+		return 2;
+}
+
+static int yaffs_do_sync_fs(struct super_block *sb, int request_checkpoint)
+{
+
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+	unsigned int oneshot_checkpoint = (yaffs_auto_checkpoint & 4);
+	unsigned gc_urgent = yaffs_bg_gc_urgency(dev);
+	int do_checkpoint;
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
+		"yaffs_do_sync_fs: gc-urgency %d %s %s%s",
+		gc_urgent,
+		sb->s_dirt ? "dirty" : "clean",
+		request_checkpoint ? "checkpoint requested" : "no checkpoint",
+		oneshot_checkpoint ? " one-shot" : "");
+
+	yaffs_gross_lock(dev);
+	do_checkpoint = ((request_checkpoint && !gc_urgent) ||
+			 oneshot_checkpoint) && !dev->is_checkpointed;
+
+	if (sb->s_dirt || do_checkpoint) {
+		yaffs_flush_super(sb, !dev->is_checkpointed && do_checkpoint);
+		sb->s_dirt = 0;
+		if (oneshot_checkpoint)
+			yaffs_auto_checkpoint &= ~4;
+	}
+	yaffs_gross_unlock(dev);
+
+	return 0;
+}
+
+/*
+ * yaffs background thread functions .
+ * yaffs_bg_thread_fn() the thread function
+ * yaffs_bg_start() launches the background thread.
+ * yaffs_bg_stop() cleans up the background thread.
+ *
+ * NB:
+ * The thread should only run after the yaffs is initialised
+ * The thread should be stopped before yaffs is unmounted.
+ * The thread should not do any writing while the fs is in read only.
+ */
+
+void yaffs_background_waker(unsigned long data)
+{
+	wake_up_process((struct task_struct *)data);
+}
+
+static int yaffs_bg_thread_fn(void *data)
+{
+	struct yaffs_dev *dev = (struct yaffs_dev *)data;
+	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
+	unsigned long now = jiffies;
+	unsigned long next_dir_update = now;
+	unsigned long next_gc = now;
+	unsigned long expires;
+	unsigned int urgency;
+	int gc_result;
+	struct timer_list timer;
+
+	yaffs_trace(YAFFS_TRACE_BACKGROUND,
+		"yaffs_background starting for dev %p", (void *)dev);
+
+	set_freezable();
+	while (context->bg_running) {
+		yaffs_trace(YAFFS_TRACE_BACKGROUND, "yaffs_background");
+
+		if (kthread_should_stop())
+			break;
+
+		if (try_to_freeze())
+			continue;
+
+		yaffs_gross_lock(dev);
+
+		now = jiffies;
+
+		if (time_after(now, next_dir_update) && yaffs_bg_enable) {
+			yaffs_update_dirty_dirs(dev);
+			next_dir_update = now + HZ;
+		}
+
+		if (time_after(now, next_gc) && yaffs_bg_enable) {
+			if (!dev->is_checkpointed) {
+				urgency = yaffs_bg_gc_urgency(dev);
+				gc_result = yaffs_bg_gc(dev, urgency);
+				if (urgency > 1)
+					next_gc = now + HZ / 20 + 1;
+				else if (urgency > 0)
+					next_gc = now + HZ / 10 + 1;
+				else
+					next_gc = now + HZ * 2;
+			} else	{
+				/*
+				 * gc not running so set to next_dir_update
+				 * to cut down on wake ups
+				 */
+				next_gc = next_dir_update;
+			}
+		}
+		yaffs_gross_unlock(dev);
+		expires = next_dir_update;
+		if (time_before(next_gc, expires))
+			expires = next_gc;
+		if (time_before(expires, now))
+			expires = now + HZ;
+
+		init_timer_on_stack(&timer);
+		timer.expires = expires + 1;
+		timer.data = (unsigned long)current;
+		timer.function = yaffs_background_waker;
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		add_timer(&timer);
+		schedule();
+		del_timer_sync(&timer);
+	}
+
+	return 0;
+}
+
+static int yaffs_bg_start(struct yaffs_dev *dev)
+{
+	int retval = 0;
+	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
+
+	if (dev->read_only)
+		return -1;
+
+	context->bg_running = 1;
+
+	context->bg_thread = kthread_run(yaffs_bg_thread_fn,
+					 (void *)dev, "yaffs-bg-%d",
+					 context->mount_id);
+
+	if (IS_ERR(context->bg_thread)) {
+		retval = PTR_ERR(context->bg_thread);
+		context->bg_thread = NULL;
+		context->bg_running = 0;
+	}
+	return retval;
+}
+
+static void yaffs_bg_stop(struct yaffs_dev *dev)
+{
+	struct yaffs_linux_context *ctxt = yaffs_dev_to_lc(dev);
+
+	ctxt->bg_running = 0;
+
+	if (ctxt->bg_thread) {
+		kthread_stop(ctxt->bg_thread);
+		ctxt->bg_thread = NULL;
+	}
+}
+
+static void yaffs_write_super(struct super_block *sb)
+{
+	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 2);
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
+		"yaffs_write_super%s",
+		request_checkpoint ? " checkpt" : "");
+
+	yaffs_do_sync_fs(sb, request_checkpoint);
+
+}
+
+static int yaffs_sync_fs(struct super_block *sb, int wait)
+{
+	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 1);
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC,
+		"yaffs_sync_fs%s", request_checkpoint ? " checkpt" : "");
+
+	yaffs_do_sync_fs(sb, request_checkpoint);
+
+	return 0;
+}
+
+static LIST_HEAD(yaffs_context_list);
+struct mutex yaffs_context_lock;
+
+struct yaffs_options {
+	int inband_tags;
+	int skip_checkpoint_read;
+	int skip_checkpoint_write;
+	int no_cache;
+	int tags_ecc_on;
+	int tags_ecc_overridden;
+	int lazy_loading_enabled;
+	int lazy_loading_overridden;
+	int empty_lost_and_found;
+	int empty_lost_and_found_overridden;
+};
+
+#define MAX_OPT_LEN 30
+static int yaffs_parse_options(struct yaffs_options *options,
+				const char *options_str)
+{
+	char cur_opt[MAX_OPT_LEN + 1];
+	int p;
+	int error = 0;
+
+	/* Parse through the options which is a comma seperated list */
+
+	while (options_str && *options_str && !error) {
+		memset(cur_opt, 0, MAX_OPT_LEN + 1);
+		p = 0;
+
+		while (*options_str == ',')
+			options_str++;
+
+		while (*options_str && *options_str != ',') {
+			if (p < MAX_OPT_LEN) {
+				cur_opt[p] = *options_str;
+				p++;
+			}
+			options_str++;
+		}
+
+		if (!strcmp(cur_opt, "inband-tags")) {
+			options->inband_tags = 1;
+		} else if (!strcmp(cur_opt, "tags-ecc-off")) {
+			options->tags_ecc_on = 0;
+			options->tags_ecc_overridden = 1;
+		} else if (!strcmp(cur_opt, "tags-ecc-on")) {
+			options->tags_ecc_on = 1;
+			options->tags_ecc_overridden = 1;
+		} else if (!strcmp(cur_opt, "lazy-loading-off")) {
+			options->lazy_loading_enabled = 0;
+			options->lazy_loading_overridden = 1;
+		} else if (!strcmp(cur_opt, "lazy-loading-on")) {
+			options->lazy_loading_enabled = 1;
+			options->lazy_loading_overridden = 1;
+		} else if (!strcmp(cur_opt, "empty-lost-and-found-off")) {
+			options->empty_lost_and_found = 0;
+			options->empty_lost_and_found_overridden = 1;
+		} else if (!strcmp(cur_opt, "empty-lost-and-found-on")) {
+			options->empty_lost_and_found = 1;
+			options->empty_lost_and_found_overridden = 1;
+		} else if (!strcmp(cur_opt, "no-cache")) {
+			options->no_cache = 1;
+		} else if (!strcmp(cur_opt, "no-checkpoint-read")) {
+			options->skip_checkpoint_read = 1;
+		} else if (!strcmp(cur_opt, "no-checkpoint-write")) {
+			options->skip_checkpoint_write = 1;
+		} else if (!strcmp(cur_opt, "no-checkpoint")) {
+			options->skip_checkpoint_read = 1;
+			options->skip_checkpoint_write = 1;
+		} else {
+			printk(KERN_INFO "yaffs: Bad mount option \"%s\"\n",
+			       cur_opt);
+			error = 1;
+		}
+	}
+	return error;
+}
+
+static const struct address_space_operations yaffs_file_address_operations = {
+	.readpage = yaffs_readpage,
+	.writepage = yaffs_writepage,
+	.write_begin = yaffs_write_begin,
+	.write_end = yaffs_write_end,
+};
+
+
+
+static const struct inode_operations yaffs_file_inode_operations = {
+	.setattr = yaffs_setattr,
+#ifdef CONFIG_YAFFS_XATTR
+	.setxattr = yaffs_setxattr,
+	.getxattr = yaffs_getxattr,
+	.listxattr = yaffs_listxattr,
+	.removexattr = yaffs_removexattr,
+#endif
+};
+
+static const struct inode_operations yaffs_symlink_inode_operations = {
+	.readlink = yaffs_readlink,
+	.follow_link = yaffs_follow_link,
+	.put_link = yaffs_put_link,
+	.setattr = yaffs_setattr,
+#ifdef CONFIG_YAFFS_XATTR
+	.setxattr = yaffs_setxattr,
+	.getxattr = yaffs_getxattr,
+	.listxattr = yaffs_listxattr,
+	.removexattr = yaffs_removexattr,
+#endif
+};
+
+static void yaffs_fill_inode_from_obj(struct inode *inode,
+				      struct yaffs_obj *obj)
+{
+	if (inode && obj) {
+		/* Check mode against the variant type
+		 * and attempt to repair if broken. */
+		u32 mode = obj->yst_mode;
+		switch (obj->variant_type) {
+		case YAFFS_OBJECT_TYPE_FILE:
+			if (!S_ISREG(mode)) {
+				obj->yst_mode &= ~S_IFMT;
+				obj->yst_mode |= S_IFREG;
+			}
+
+			break;
+		case YAFFS_OBJECT_TYPE_SYMLINK:
+			if (!S_ISLNK(mode)) {
+				obj->yst_mode &= ~S_IFMT;
+				obj->yst_mode |= S_IFLNK;
+			}
+
+			break;
+		case YAFFS_OBJECT_TYPE_DIRECTORY:
+			if (!S_ISDIR(mode)) {
+				obj->yst_mode &= ~S_IFMT;
+				obj->yst_mode |= S_IFDIR;
+			}
+
+			break;
+		case YAFFS_OBJECT_TYPE_UNKNOWN:
+		case YAFFS_OBJECT_TYPE_HARDLINK:
+		case YAFFS_OBJECT_TYPE_SPECIAL:
+		default:
+			/* TODO? */
+			break;
+		}
+
+		inode->i_flags |= S_NOATIME;
+
+		inode->i_ino = obj->obj_id;
+		inode->i_mode = obj->yst_mode;
+		inode->i_uid = obj->yst_uid;
+		inode->i_gid = obj->yst_gid;
+
+		inode->i_rdev = old_decode_dev(obj->yst_rdev);
+
+		inode->i_atime.tv_sec = (time_t) (obj->yst_atime);
+		inode->i_atime.tv_nsec = 0;
+		inode->i_mtime.tv_sec = (time_t) obj->yst_mtime;
+		inode->i_mtime.tv_nsec = 0;
+		inode->i_ctime.tv_sec = (time_t) obj->yst_ctime;
+		inode->i_ctime.tv_nsec = 0;
+		inode->i_size = yaffs_get_obj_length(obj);
+		inode->i_blocks = (inode->i_size + 511) >> 9;
+
+		inode->i_nlink = yaffs_get_obj_link_count(obj);
+
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_fill_inode mode %x uid %d gid %d size %d count %d",
+			inode->i_mode, inode->i_uid, inode->i_gid,
+			(int)inode->i_size, atomic_read(&inode->i_count));
+
+		switch (obj->yst_mode & S_IFMT) {
+		default:	/* fifo, device or socket */
+			init_special_inode(inode, obj->yst_mode,
+					   old_decode_dev(obj->yst_rdev));
+			break;
+		case S_IFREG:	/* file */
+			inode->i_op = &yaffs_file_inode_operations;
+			inode->i_fop = &yaffs_file_operations;
+			inode->i_mapping->a_ops =
+			    &yaffs_file_address_operations;
+			break;
+		case S_IFDIR:	/* directory */
+			inode->i_op = &yaffs_dir_inode_operations;
+			inode->i_fop = &yaffs_dir_operations;
+			break;
+		case S_IFLNK:	/* symlink */
+			inode->i_op = &yaffs_symlink_inode_operations;
+			break;
+		}
+
+		yaffs_inode_to_obj_lv(inode) = obj;
+		obj->my_inode = inode;
+
+	} else {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_fill_inode invalid parameters");
+	}
+}
+
+static void yaffs_put_super(struct super_block *sb)
+{
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_put_super");
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
+		"Shutting down yaffs background thread");
+	yaffs_bg_stop(dev);
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
+		"yaffs background thread shut down");
+
+	yaffs_gross_lock(dev);
+
+	yaffs_flush_super(sb, 1);
+
+	if (yaffs_dev_to_lc(dev)->put_super_fn)
+		yaffs_dev_to_lc(dev)->put_super_fn(sb);
+
+	yaffs_deinitialise(dev);
+
+	yaffs_gross_unlock(dev);
+	mutex_lock(&yaffs_context_lock);
+	list_del_init(&(yaffs_dev_to_lc(dev)->context_list));
+	mutex_unlock(&yaffs_context_lock);
+
+	if (yaffs_dev_to_lc(dev)->spare_buffer) {
+		kfree(yaffs_dev_to_lc(dev)->spare_buffer);
+		yaffs_dev_to_lc(dev)->spare_buffer = NULL;
+	}
+
+	kfree(dev);
+}
+
+static void yaffs_mtd_put_super(struct super_block *sb)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(yaffs_super_to_dev(sb));
+
+	if (mtd->sync)
+		mtd->sync(mtd);
+
+	put_mtd_device(mtd);
+}
+
+static const struct super_operations yaffs_super_ops = {
+	.statfs = yaffs_statfs,
+	.put_super = yaffs_put_super,
+	.evict_inode = yaffs_evict_inode,
+	.sync_fs = yaffs_sync_fs,
+	.write_super = yaffs_write_super,
+};
+
+static struct super_block *yaffs_internal_read_super(int yaffs_version,
+						     struct super_block *sb,
+						     void *data, int silent)
+{
+	int n_blocks;
+	struct inode *inode = NULL;
+	struct dentry *root;
+	struct yaffs_dev *dev = 0;
+	char devname_buf[BDEVNAME_SIZE + 1];
+	struct mtd_info *mtd;
+	int err;
+	char *data_str = (char *)data;
+	struct yaffs_linux_context *context = NULL;
+	struct yaffs_param *param;
+	int read_only = 0;
+	struct yaffs_options options;
+	unsigned mount_id;
+	int found;
+	struct yaffs_linux_context *context_iterator;
+	struct list_head *l;
+
+	if (!sb) {
+		printk(KERN_INFO "yaffs: sb is NULL\n");
+		return NULL;
+	}
+
+	sb->s_magic = YAFFS_MAGIC;
+	sb->s_op = &yaffs_super_ops;
+	sb->s_flags |= MS_NOATIME;
+
+	read_only = ((sb->s_flags & MS_RDONLY) != 0);
+
+	sb->s_export_op = &yaffs_export_ops;
+
+	if (!sb->s_dev)
+		printk(KERN_INFO "yaffs: sb->s_dev is NULL\n");
+	else if (!yaffs_devname(sb, devname_buf))
+		printk(KERN_INFO "yaffs: devname is NULL\n");
+	else
+		printk(KERN_INFO "yaffs: dev is %d name is \"%s\" %s\n",
+		       sb->s_dev,
+		       yaffs_devname(sb, devname_buf), read_only ? "ro" : "rw");
+
+	if (!data_str)
+		data_str = "";
+
+	printk(KERN_INFO "yaffs: passed flags \"%s\"\n", data_str);
+
+	memset(&options, 0, sizeof(options));
+
+	if (yaffs_parse_options(&options, data_str)) {
+		/* Option parsing failed */
+		return NULL;
+	}
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_read_super: Using yaffs%d", yaffs_version);
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_read_super: block size %d", (int)(sb->s_blocksize));
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"Attempting MTD mount of %u.%u,\"%s\"",
+		MAJOR(sb->s_dev), MINOR(sb->s_dev),
+		yaffs_devname(sb, devname_buf));
+
+	/* Check it's an mtd device..... */
+	if (MAJOR(sb->s_dev) != MTD_BLOCK_MAJOR)
+		return NULL;	/* This isn't an mtd device */
+
+	/* Get the device */
+	mtd = get_mtd_device(NULL, MINOR(sb->s_dev));
+	if (!mtd) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"MTD device #%u doesn't appear to exist",
+			MINOR(sb->s_dev));
+		return NULL;
+	}
+	/* Check it's NAND */
+	if (mtd->type != MTD_NANDFLASH) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"MTD device is not NAND it's type %d",
+			mtd->type);
+		return NULL;
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS, " erase %p", mtd->erase);
+	yaffs_trace(YAFFS_TRACE_OS, " read %p", mtd->read);
+	yaffs_trace(YAFFS_TRACE_OS, " write %p", mtd->write);
+	yaffs_trace(YAFFS_TRACE_OS, " readoob %p", mtd->read_oob);
+	yaffs_trace(YAFFS_TRACE_OS, " writeoob %p", mtd->write_oob);
+	yaffs_trace(YAFFS_TRACE_OS, " block_isbad %p", mtd->block_isbad);
+	yaffs_trace(YAFFS_TRACE_OS, " block_markbad %p", mtd->block_markbad);
+	yaffs_trace(YAFFS_TRACE_OS, " writesize %d", mtd->writesize);
+	yaffs_trace(YAFFS_TRACE_OS, " oobsize %d", mtd->oobsize);
+	yaffs_trace(YAFFS_TRACE_OS, " erasesize %d", mtd->erasesize);
+	yaffs_trace(YAFFS_TRACE_OS, " size %lld", mtd->size);
+
+#ifdef CONFIG_YAFFS_AUTO_YAFFS2
+
+	if (yaffs_version == 1 && mtd->writesize >= 2048) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs2");
+		yaffs_version = 2;
+	}
+
+	/* Added NCB 26/5/2006 for completeness */
+	if (yaffs_version == 2 && !options.inband_tags &&
+		mtd->writesize == 512) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs1");
+		yaffs_version = 1;
+	}
+#endif
+
+	if (yaffs_version == 2) {
+		/* Check for version 2 style functions */
+		if (!mtd->erase ||
+		    !mtd->block_isbad ||
+		    !mtd->block_markbad ||
+		    !mtd->read ||
+		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not support required functions");
+			return NULL;
+		}
+
+		if ((mtd->writesize < YAFFS_MIN_YAFFS2_CHUNK_SIZE ||
+		     mtd->oobsize < YAFFS_MIN_YAFFS2_SPARE_SIZE) &&
+		    !options.inband_tags) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not have the right page sizes");
+			return NULL;
+		}
+	} else {
+		/* Check for V1 style functions */
+		if (!mtd->erase ||
+		    !mtd->read ||
+		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not support required functions");
+			return NULL;
+		}
+
+		if (mtd->writesize < YAFFS_BYTES_PER_CHUNK ||
+		    mtd->oobsize != YAFFS_BYTES_PER_SPARE) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not support have the right page sizes");
+			return NULL;
+		}
+	}
+
+	/* OK, so if we got here, we have an MTD that's NAND and looks
+	 * like it has the right capabilities
+	 * Set the struct yaffs_dev up for mtd
+	 */
+
+	if (!read_only && !(mtd->flags & MTD_WRITEABLE)) {
+		read_only = 1;
+		printk(KERN_INFO
+		       "yaffs: mtd is read only, setting superblock read only");
+		sb->s_flags |= MS_RDONLY;
+	}
+
+	dev = kmalloc(sizeof(struct yaffs_dev), GFP_KERNEL);
+	context = kmalloc(sizeof(struct yaffs_linux_context), GFP_KERNEL);
+
+	if (!dev || !context) {
+		kfree(dev);
+		kfree(context);
+		dev = NULL;
+		context = NULL;
+	}
+
+	if (!dev) {
+		/* Deep shit could not allocate device structure */
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"yaffs_read_super failed trying to allocate yaffs_dev");
+		return NULL;
+	}
+	memset(dev, 0, sizeof(struct yaffs_dev));
+	param = &(dev->param);
+
+	memset(context, 0, sizeof(struct yaffs_linux_context));
+	dev->os_context = context;
+	INIT_LIST_HEAD(&(context->context_list));
+	context->dev = dev;
+	context->super = sb;
+
+	dev->read_only = read_only;
+
+	sb->s_fs_info = dev;
+
+	dev->driver_context = mtd;
+	param->name = mtd->name;
+
+	/* Set up the memory size parameters.... */
+
+	n_blocks =
+	    YCALCBLOCKS(mtd->size,
+			(YAFFS_CHUNKS_PER_BLOCK * YAFFS_BYTES_PER_CHUNK));
+
+	param->start_block = 0;
+	param->end_block = n_blocks - 1;
+	param->chunks_per_block = YAFFS_CHUNKS_PER_BLOCK;
+	param->total_bytes_per_chunk = YAFFS_BYTES_PER_CHUNK;
+	param->n_reserved_blocks = 5;
+	param->n_caches = (options.no_cache) ? 0 : 10;
+	param->inband_tags = options.inband_tags;
+
+#ifdef CONFIG_YAFFS_DISABLE_LAZY_LOAD
+	param->disable_lazy_load = 1;
+#endif
+#ifdef CONFIG_YAFFS_XATTR
+	param->enable_xattr = 1;
+#endif
+	if (options.lazy_loading_overridden)
+		param->disable_lazy_load = !options.lazy_loading_enabled;
+
+#ifdef CONFIG_YAFFS_DISABLE_TAGS_ECC
+	param->no_tags_ecc = 1;
+#endif
+
+#ifdef CONFIG_YAFFS_DISABLE_BACKGROUND
+#else
+	param->defered_dir_update = 1;
+#endif
+
+	if (options.tags_ecc_overridden)
+		param->no_tags_ecc = !options.tags_ecc_on;
+
+#ifdef CONFIG_YAFFS_EMPTY_LOST_AND_FOUND
+	param->empty_lost_n_found = 1;
+#endif
+
+#ifdef CONFIG_YAFFS_DISABLE_BLOCK_REFRESHING
+	param->refresh_period = 0;
+#else
+	param->refresh_period = 500;
+#endif
+
+#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
+	param->always_check_erased = 1;
+#endif
+
+	if (options.empty_lost_and_found_overridden)
+		param->empty_lost_n_found = options.empty_lost_and_found;
+
+	/* ... and the functions. */
+	if (yaffs_version == 2) {
+		param->write_chunk_tags_fn = nandmtd2_write_chunk_tags;
+		param->read_chunk_tags_fn = nandmtd2_read_chunk_tags;
+		param->bad_block_fn = nandmtd2_mark_block_bad;
+		param->query_block_fn = nandmtd2_query_block;
+		yaffs_dev_to_lc(dev)->spare_buffer =
+				kmalloc(mtd->oobsize, GFP_NOFS);
+		param->is_yaffs2 = 1;
+		param->total_bytes_per_chunk = mtd->writesize;
+		param->chunks_per_block = mtd->erasesize / mtd->writesize;
+		n_blocks = YCALCBLOCKS(mtd->size, mtd->erasesize);
+
+		param->start_block = 0;
+		param->end_block = n_blocks - 1;
+	} else {
+		/* use the MTD interface in yaffs_mtdif1.c */
+		param->write_chunk_tags_fn = nandmtd1_write_chunk_tags;
+		param->read_chunk_tags_fn = nandmtd1_read_chunk_tags;
+		param->bad_block_fn = nandmtd1_mark_block_bad;
+		param->query_block_fn = nandmtd1_query_block;
+		param->is_yaffs2 = 0;
+	}
+	/* ... and common functions */
+	param->erase_fn = nandmtd_erase_block;
+	param->initialise_flash_fn = nandmtd_initialise;
+
+	yaffs_dev_to_lc(dev)->put_super_fn = yaffs_mtd_put_super;
+
+	param->sb_dirty_fn = yaffs_touch_super;
+	param->gc_control = yaffs_gc_control_callback;
+
+	yaffs_dev_to_lc(dev)->super = sb;
+
+#ifndef CONFIG_YAFFS_DOES_ECC
+	param->use_nand_ecc = 1;
+#endif
+
+	param->skip_checkpt_rd = options.skip_checkpoint_read;
+	param->skip_checkpt_wr = options.skip_checkpoint_write;
+
+	mutex_lock(&yaffs_context_lock);
+	/* Get a mount id */
+	found = 0;
+	for (mount_id = 0; !found; mount_id++) {
+		found = 1;
+		list_for_each(l, &yaffs_context_list) {
+			context_iterator =
+				list_entry(l, struct yaffs_linux_context,
+					context_list);
+			if (context_iterator->mount_id == mount_id)
+				found = 0;
+		}
+	}
+	context->mount_id = mount_id;
+
+	list_add_tail(&(yaffs_dev_to_lc(dev)->context_list),
+		      &yaffs_context_list);
+	mutex_unlock(&yaffs_context_lock);
+
+	/* Directory search handling... */
+	INIT_LIST_HEAD(&(yaffs_dev_to_lc(dev)->search_contexts));
+	param->remove_obj_fn = yaffs_remove_obj_callback;
+
+	mutex_init(&(yaffs_dev_to_lc(dev)->gross_lock));
+
+	yaffs_gross_lock(dev);
+
+	err = yaffs_guts_initialise(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_read_super: guts initialised %s",
+		(err == YAFFS_OK) ? "OK" : "FAILED");
+
+	if (err == YAFFS_OK)
+		yaffs_bg_start(dev);
+
+	if (!context->bg_thread)
+		param->defered_dir_update = 0;
+
+	/* Release lock before yaffs_get_inode() */
+	yaffs_gross_unlock(dev);
+
+	/* Create root inode */
+	if (err == YAFFS_OK)
+		inode = yaffs_get_inode(sb, S_IFDIR | 0755, 0, yaffs_root(dev));
+
+	if (!inode)
+		return NULL;
+
+	inode->i_op = &yaffs_dir_inode_operations;
+	inode->i_fop = &yaffs_dir_operations;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: got root inode");
+
+	root = d_alloc_root(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: d_alloc_root done");
+
+	if (!root) {
+		iput(inode);
+		return NULL;
+	}
+	sb->s_root = root;
+	sb->s_dirt = !dev->is_checkpointed;
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"yaffs_read_super: is_checkpointed %d",
+		dev->is_checkpointed);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: done");
+	return sb;
+}
+
+static int yaffs_internal_read_super_mtd(struct super_block *sb, void *data,
+					 int silent)
+{
+	return yaffs_internal_read_super(1, sb, data, silent) ? 0 : -EINVAL;
+}
+
+static int yaffs_read_super(struct file_system_type *fs,
+			    int flags, const char *dev_name,
+			    void *data, struct vfsmount *mnt)
+{
+
+	return get_sb_bdev(fs, flags, dev_name, data,
+			   yaffs_internal_read_super_mtd, mnt);
+}
+
+static struct file_system_type yaffs_fs_type = {
+	.owner = THIS_MODULE,
+	.name = "yaffs",
+	.get_sb = yaffs_read_super,
+	.kill_sb = kill_block_super,
+	.fs_flags = FS_REQUIRES_DEV,
+};
+
+#ifdef CONFIG_YAFFS_YAFFS2
+
+static int yaffs2_internal_read_super_mtd(struct super_block *sb, void *data,
+					  int silent)
+{
+	return yaffs_internal_read_super(2, sb, data, silent) ? 0 : -EINVAL;
+}
+
+static int yaffs2_read_super(struct file_system_type *fs,
+			     int flags, const char *dev_name, void *data,
+			     struct vfsmount *mnt)
+{
+	return get_sb_bdev(fs, flags, dev_name, data,
+			   yaffs2_internal_read_super_mtd, mnt);
+}
+
+static struct file_system_type yaffs2_fs_type = {
+	.owner = THIS_MODULE,
+	.name = "yaffs2",
+	.get_sb = yaffs2_read_super,
+	.kill_sb = kill_block_super,
+	.fs_flags = FS_REQUIRES_DEV,
+};
+#endif /* CONFIG_YAFFS_YAFFS2 */
+
+static struct proc_dir_entry *my_proc_entry;
+
+static char *yaffs_dump_dev_part0(char *buf, struct yaffs_dev *dev)
+{
+	struct yaffs_param *param = &dev->param;
+
+	buf += sprintf(buf, "start_block........... %d\n", param->start_block);
+	buf += sprintf(buf, "end_block............. %d\n", param->end_block);
+	buf += sprintf(buf, "total_bytes_per_chunk. %d\n",
+			param->total_bytes_per_chunk);
+	buf += sprintf(buf, "use_nand_ecc.......... %d\n",
+			param->use_nand_ecc);
+	buf += sprintf(buf, "no_tags_ecc........... %d\n", param->no_tags_ecc);
+	buf += sprintf(buf, "is_yaffs2............. %d\n", param->is_yaffs2);
+	buf += sprintf(buf, "inband_tags........... %d\n", param->inband_tags);
+	buf += sprintf(buf, "empty_lost_n_found.... %d\n",
+			param->empty_lost_n_found);
+	buf += sprintf(buf, "disable_lazy_load..... %d\n",
+			param->disable_lazy_load);
+	buf += sprintf(buf, "refresh_period........ %d\n",
+			param->refresh_period);
+	buf += sprintf(buf, "n_caches.............. %d\n", param->n_caches);
+	buf += sprintf(buf, "n_reserved_blocks..... %d\n",
+			param->n_reserved_blocks);
+	buf += sprintf(buf, "always_check_erased... %d\n",
+			param->always_check_erased);
+
+	return buf;
+}
+
+static char *yaffs_dump_dev_part1(char *buf, struct yaffs_dev *dev)
+{
+	buf +=
+	    sprintf(buf, "data_bytes_per_chunk.. %d\n",
+		    dev->data_bytes_per_chunk);
+	buf += sprintf(buf, "chunk_grp_bits........ %d\n", dev->chunk_grp_bits);
+	buf += sprintf(buf, "chunk_grp_size........ %d\n", dev->chunk_grp_size);
+	buf +=
+	    sprintf(buf, "n_erased_blocks....... %d\n", dev->n_erased_blocks);
+	buf +=
+	    sprintf(buf, "blocks_in_checkpt..... %d\n", dev->blocks_in_checkpt);
+	buf += sprintf(buf, "\n");
+	buf += sprintf(buf, "n_tnodes.............. %d\n", dev->n_tnodes);
+	buf += sprintf(buf, "n_obj................. %d\n", dev->n_obj);
+	buf += sprintf(buf, "n_free_chunks......... %d\n", dev->n_free_chunks);
+	buf += sprintf(buf, "\n");
+	buf += sprintf(buf, "n_page_writes......... %u\n", dev->n_page_writes);
+	buf += sprintf(buf, "n_page_reads.......... %u\n", dev->n_page_reads);
+	buf += sprintf(buf, "n_erasures............ %u\n", dev->n_erasures);
+	buf += sprintf(buf, "n_gc_copies........... %u\n", dev->n_gc_copies);
+	buf += sprintf(buf, "all_gcs............... %u\n", dev->all_gcs);
+	buf +=
+	    sprintf(buf, "passive_gc_count...... %u\n", dev->passive_gc_count);
+	buf +=
+	    sprintf(buf, "oldest_dirty_gc_count. %u\n",
+		    dev->oldest_dirty_gc_count);
+	buf += sprintf(buf, "n_gc_blocks........... %u\n", dev->n_gc_blocks);
+	buf += sprintf(buf, "bg_gcs................ %u\n", dev->bg_gcs);
+	buf +=
+	    sprintf(buf, "n_retired_writes...... %u\n", dev->n_retired_writes);
+	buf +=
+	    sprintf(buf, "n_retired_blocks...... %u\n", dev->n_retired_blocks);
+	buf += sprintf(buf, "n_ecc_fixed........... %u\n", dev->n_ecc_fixed);
+	buf += sprintf(buf, "n_ecc_unfixed......... %u\n", dev->n_ecc_unfixed);
+	buf +=
+	    sprintf(buf, "n_tags_ecc_fixed...... %u\n", dev->n_tags_ecc_fixed);
+	buf +=
+	    sprintf(buf, "n_tags_ecc_unfixed.... %u\n",
+		    dev->n_tags_ecc_unfixed);
+	buf += sprintf(buf, "cache_hits............ %u\n", dev->cache_hits);
+	buf +=
+	    sprintf(buf, "n_deleted_files....... %u\n", dev->n_deleted_files);
+	buf +=
+	    sprintf(buf, "n_unlinked_files...... %u\n", dev->n_unlinked_files);
+	buf += sprintf(buf, "refresh_count......... %u\n", dev->refresh_count);
+	buf += sprintf(buf, "n_bg_deletions........ %u\n", dev->n_bg_deletions);
+
+	return buf;
+}
+
+static int yaffs_proc_read(char *page,
+			   char **start,
+			   off_t offset, int count, int *eof, void *data)
+{
+	struct list_head *item;
+	char *buf = page;
+	int step = offset;
+	int n = 0;
+
+	/* Get proc_file_read() to step 'offset' by one on each sucessive call.
+	 * We use 'offset' (*ppos) to indicate where we are in dev_list.
+	 * This also assumes the user has posted a read buffer large
+	 * enough to hold the complete output; but that's life in /proc.
+	 */
+
+	*(int *)start = 1;
+
+	/* Print header first */
+	if (step == 0)
+		buf += sprintf(buf, "YAFFS built:" __DATE__ " " __TIME__ "\n");
+	else if (step == 1)
+		buf += sprintf(buf, "\n");
+	else {
+		step -= 2;
+
+		mutex_lock(&yaffs_context_lock);
+
+		/* Locate and print the Nth entry.
+		 * Order N-squared but N is small. */
+		list_for_each(item, &yaffs_context_list) {
+			struct yaffs_linux_context *dc =
+			    list_entry(item, struct yaffs_linux_context,
+				       context_list);
+			struct yaffs_dev *dev = dc->dev;
+
+			if (n < (step & ~1)) {
+				n += 2;
+				continue;
+			}
+			if ((step & 1) == 0) {
+				buf +=
+				    sprintf(buf, "\nDevice %d \"%s\"\n", n,
+					    dev->param.name);
+				buf = yaffs_dump_dev_part0(buf, dev);
+			} else {
+				buf = yaffs_dump_dev_part1(buf, dev);
+			}
+
+			break;
+		}
+		mutex_unlock(&yaffs_context_lock);
+	}
+
+	return buf - page < count ? buf - page : count;
+}
+
+
+/**
+ * Set the verbosity of the warnings and error messages.
+ *
+ * Note that the names can only be a..z or _ with the current code.
+ */
+
+static struct {
+	char *mask_name;
+	unsigned mask_bitfield;
+} mask_flags[] = {
+	{"allocate", YAFFS_TRACE_ALLOCATE},
+	{"always", YAFFS_TRACE_ALWAYS},
+	{"background", YAFFS_TRACE_BACKGROUND},
+	{"bad_blocks", YAFFS_TRACE_BAD_BLOCKS},
+	{"buffers", YAFFS_TRACE_BUFFERS},
+	{"bug", YAFFS_TRACE_BUG},
+	{"checkpt", YAFFS_TRACE_CHECKPOINT},
+	{"deletion", YAFFS_TRACE_DELETION},
+	{"erase", YAFFS_TRACE_ERASE},
+	{"error", YAFFS_TRACE_ERROR},
+	{"gc_detail", YAFFS_TRACE_GC_DETAIL},
+	{"gc", YAFFS_TRACE_GC},
+	{"lock", YAFFS_TRACE_LOCK},
+	{"mtd", YAFFS_TRACE_MTD},
+	{"nandaccess", YAFFS_TRACE_NANDACCESS},
+	{"os", YAFFS_TRACE_OS},
+	{"scan_debug", YAFFS_TRACE_SCAN_DEBUG},
+	{"scan", YAFFS_TRACE_SCAN},
+	{"mount", YAFFS_TRACE_MOUNT},
+	{"tracing", YAFFS_TRACE_TRACING},
+	{"sync", YAFFS_TRACE_SYNC},
+	{"write", YAFFS_TRACE_WRITE},
+	{"verify", YAFFS_TRACE_VERIFY},
+	{"verify_nand", YAFFS_TRACE_VERIFY_NAND},
+	{"verify_full", YAFFS_TRACE_VERIFY_FULL},
+	{"verify_all", YAFFS_TRACE_VERIFY_ALL},
+	{"all", 0xffffffff},
+	{"none", 0},
+	{NULL, 0},
+};
+
+#define MAX_MASK_NAME_LENGTH 40
+static int yaffs_proc_write_trace_options(struct file *file, const char *buf,
+					  unsigned long count, void *data)
+{
+	unsigned rg = 0, mask_bitfield;
+	char *end;
+	char *mask_name;
+	const char *x;
+	char substring[MAX_MASK_NAME_LENGTH + 1];
+	int i;
+	int done = 0;
+	int add, len = 0;
+	int pos = 0;
+
+	rg = yaffs_trace_mask;
+
+	while (!done && (pos < count)) {
+		done = 1;
+		while ((pos < count) && isspace(buf[pos]))
+			pos++;
+
+		switch (buf[pos]) {
+		case '+':
+		case '-':
+		case '=':
+			add = buf[pos];
+			pos++;
+			break;
+
+		default:
+			add = ' ';
+			break;
+		}
+		mask_name = NULL;
+
+		mask_bitfield = simple_strtoul(buf + pos, &end, 0);
+
+		if (end > buf + pos) {
+			mask_name = "numeral";
+			len = end - (buf + pos);
+			pos += len;
+			done = 0;
+		} else {
+			for (x = buf + pos, i = 0;
+			     (*x == '_' || (*x >= 'a' && *x <= 'z')) &&
+			     i < MAX_MASK_NAME_LENGTH; x++, i++, pos++)
+				substring[i] = *x;
+			substring[i] = '\0';
+
+			for (i = 0; mask_flags[i].mask_name != NULL; i++) {
+				if (strcmp(substring, mask_flags[i].mask_name)
+				    == 0) {
+					mask_name = mask_flags[i].mask_name;
+					mask_bitfield =
+					    mask_flags[i].mask_bitfield;
+					done = 0;
+					break;
+				}
+			}
+		}
+
+		if (mask_name != NULL) {
+			done = 0;
+			switch (add) {
+			case '-':
+				rg &= ~mask_bitfield;
+				break;
+			case '+':
+				rg |= mask_bitfield;
+				break;
+			case '=':
+				rg = mask_bitfield;
+				break;
+			default:
+				rg |= mask_bitfield;
+				break;
+			}
+		}
+	}
+
+	yaffs_trace_mask = rg | YAFFS_TRACE_ALWAYS;
+
+	printk(KERN_DEBUG "new trace = 0x%08X\n", yaffs_trace_mask);
+
+	if (rg & YAFFS_TRACE_ALWAYS) {
+		for (i = 0; mask_flags[i].mask_name != NULL; i++) {
+			char flag;
+			flag = ((rg & mask_flags[i].mask_bitfield) ==
+				mask_flags[i].mask_bitfield) ? '+' : '-';
+			printk(KERN_DEBUG "%c%s\n", flag,
+			       mask_flags[i].mask_name);
+		}
+	}
+
+	return count;
+}
+
+static int yaffs_proc_write(struct file *file, const char *buf,
+			    unsigned long count, void *data)
+{
+	return yaffs_proc_write_trace_options(file, buf, count, data);
+}
+
+/* Stuff to handle installation of file systems */
+struct file_system_to_install {
+	struct file_system_type *fst;
+	int installed;
+};
+
+static struct file_system_to_install fs_to_install[] = {
+	{&yaffs_fs_type, 0},
+	{&yaffs2_fs_type, 0},
+	{NULL, 0}
+};
+
+static int __init init_yaffs_fs(void)
+{
+	int error = 0;
+	struct file_system_to_install *fsinst;
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"yaffs built " __DATE__ " " __TIME__ " Installing.");
+
+#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"\n\nYAFFS-WARNING CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED selected.\n\n\n");
+#endif
+
+	mutex_init(&yaffs_context_lock);
+
+	/* Install the proc_fs entries */
+	my_proc_entry = create_proc_entry("yaffs",
+					  S_IRUGO | S_IFREG, NULL);
+
+	if (my_proc_entry) {
+		my_proc_entry->write_proc = yaffs_proc_write;
+		my_proc_entry->read_proc = yaffs_proc_read;
+		my_proc_entry->data = NULL;
+	} else {
+		return -ENOMEM;
+	}
+
+
+	/* Now add the file system entries */
+
+	fsinst = fs_to_install;
+
+	while (fsinst->fst && !error) {
+		error = register_filesystem(fsinst->fst);
+		if (!error)
+			fsinst->installed = 1;
+		fsinst++;
+	}
+
+	/* Any errors? uninstall  */
+	if (error) {
+		fsinst = fs_to_install;
+
+		while (fsinst->fst) {
+			if (fsinst->installed) {
+				unregister_filesystem(fsinst->fst);
+				fsinst->installed = 0;
+			}
+			fsinst++;
+		}
+	}
+
+	return error;
+}
+
+static void __exit exit_yaffs_fs(void)
+{
+
+	struct file_system_to_install *fsinst;
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"yaffs built " __DATE__ " " __TIME__ " removing.");
+
+	remove_proc_entry("yaffs", NULL);
+
+	fsinst = fs_to_install;
+
+	while (fsinst->fst) {
+		if (fsinst->installed) {
+			unregister_filesystem(fsinst->fst);
+			fsinst->installed = 0;
+		}
+		fsinst++;
+	}
+}
+
+module_init(init_yaffs_fs)
+module_exit(exit_yaffs_fs)
+
+MODULE_DESCRIPTION("YAFFS2 - a NAND specific flash file system");
+MODULE_AUTHOR("Charles Manning, Aleph One Ltd., 2002-2010");
+MODULE_LICENSE("GPL");
diff --git a/fs/yaffs2/yportenv.h b/fs/yaffs2/yportenv.h
new file mode 100644
index 0000000..6cea9fe
--- /dev/null
+++ b/fs/yaffs2/yportenv.h
@@ -0,0 +1,70 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2010 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YPORTENV_LINUX_H__
+#define __YPORTENV_LINUX_H__
+
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/xattr.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <linux/sort.h>
+#include <linux/bitops.h>
+
+#define YCHAR char
+#define YUCHAR unsigned char
+#define _Y(x)     x
+
+#define YAFFS_LOSTNFOUND_NAME		"lost+found"
+#define YAFFS_LOSTNFOUND_PREFIX		"obj"
+
+
+#define YAFFS_ROOT_MODE			0755
+#define YAFFS_LOSTNFOUND_MODE		0700
+
+#define Y_CURRENT_TIME CURRENT_TIME.tv_sec
+#define Y_TIME_CONVERT(x) (x).tv_sec
+
+#define compile_time_assertion(assertion) \
+	({ int x = __builtin_choose_expr(assertion, 0, (void)0); (void) x; })
+
+
+#ifndef Y_DUMP_STACK
+#define Y_DUMP_STACK() dump_stack()
+#endif
+
+#define yaffs_trace(msk, fmt, ...) do { \
+	if (yaffs_trace_mask & (msk)) \
+		printk(KERN_DEBUG "yaffs: " fmt "\n", ##__VA_ARGS__); \
+} while (0)
+
+#ifndef YBUG
+#define YBUG() do {\
+	yaffs_trace(YAFFS_TRACE_BUG,\
+		"bug " __FILE__ " %d",\
+		__LINE__);\
+	Y_DUMP_STACK();\
+} while (0)
+#endif
+
+#endif
-- 
1.7.1

Re: [PATCH 09/10] Add yaffs2 file system: Linux glue code

[Jesper Juhl]

On Fri, 14 Jan 2011, Charles Manning wrote:

> Signed-off-by: Charles Manning <cdhmanning@gmail.com>
> ---
...
> +static int yaffs_setxattr(struct dentry *dentry, const char *name,
> +                  const void *value, size_t size, int flags)
> +{
> +       struct inode *inode = dentry->d_inode;
> +       int error = 0;
> +       struct yaffs_dev *dev;
> +       struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +

You only use the local variable 'inode' in the call to 
yaffs_inode_to_obj(), so you could get rid of that local variable and just 
do
    struct yaffs_obj *obj = yaffs_inode_to_obj(dentry->d_inode);
this applies to a few other function in this file as well.


-- 
Jesper Juhl <jj@chaosbits.net>            http://www.chaosbits.net/
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please.

Re: [PATCH 09/10] Add yaffs2 file system: Linux glue code

[Ryan Mallon]

On 01/14/2011 04:06 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Hi Charles,

More comments below,

~Ryan

> ---
>  fs/yaffs2/yaffs_linux.h |   41 +
>  fs/yaffs2/yaffs_vfs.c   | 2756 +++++++++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yportenv.h    |   70 ++
>  3 files changed, 2867 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_linux.h
>  create mode 100644 fs/yaffs2/yaffs_vfs.c
>  create mode 100644 fs/yaffs2/yportenv.h
> 
> diff --git a/fs/yaffs2/yaffs_linux.h b/fs/yaffs2/yaffs_linux.h
> new file mode 100644
> index 0000000..8c2f399
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_linux.h
> @@ -0,0 +1,41 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_LINUX_H__
> +#define __YAFFS_LINUX_H__
> +
> +#include "yportenv.h"
> +
> +struct yaffs_linux_context {
> +	struct list_head context_list;	/* List of these we have mounted */
> +	struct yaffs_dev *dev;
> +	struct super_block *super;
> +	struct task_struct *bg_thread;	/* Background thread for this device */
> +	int bg_running;
> +	struct mutex gross_lock;	/* Gross locking mutex*/
> +	u8 *spare_buffer;	/* For mtdif2 use. Don't know the buffer size
> +				 * at compile time so we have to allocate it.
> +				 */
> +	struct list_head search_contexts;
> +	void (*put_super_fn) (struct super_block *sb);
> +
> +	struct task_struct *readdir_process;
> +	unsigned mount_id;
> +};
> +
> +#define yaffs_dev_to_lc(dev) ((struct yaffs_linux_context *)((dev)->os_context))
> +#define yaffs_dev_to_mtd(dev) ((struct mtd_info *)((dev)->driver_context))
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_vfs.c b/fs/yaffs2/yaffs_vfs.c
> new file mode 100644
> index 0000000..4a0ec0a
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_vfs.c
> @@ -0,0 +1,2756 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + * Acknowledgements:
> + * Luc van OostenRyck for numerous patches.
> + * Nick Bane for numerous patches.
> + * Nick Bane for 2.5/2.6 integration.
> + * Andras Toth for mknod rdev issue.
> + * Michael Fischer for finding the problem with inode inconsistency.
> + * Some code bodily lifted from JFFS
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +/*
> + *
> + * This is the file system front-end to YAFFS that hooks it up to
> + * the VFS.
> + *
> + * Special notes:
> + * >> 2.4: sb->u.generic_sbp points to the struct yaffs_dev associated with
> + *         this superblock
> + * >> 2.6: sb->s_fs_info  points to the struct yaffs_dev associated with this
> + *         superblock
> + * >> inode->u.generic_ip points to the associated struct yaffs_obj.
> + */
> +
> +/*
> + * NB There are two variants of Linux VFS glue code. This variant supports
> + * a single version and should not include any multi-version code.
> + */
> +#include <linux/version.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/fs.h>
> +#include <linux/proc_fs.h>
> +#include <linux/smp_lock.h>
> +#include <linux/pagemap.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/interrupt.h>
> +#include <linux/string.h>
> +#include <linux/ctype.h>
> +#include <linux/namei.h>
> +#include <linux/exportfs.h>
> +#include <linux/kthread.h>
> +#include <linux/delay.h>
> +#include <linux/freezer.h>
> +#include <asm/div64.h>
> +#include <linux/statfs.h>
> +#include <linux/uaccess.h>
> +#include <linux/mtd/mtd.h>
> +
> +#include "yportenv.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_guts.h"
> +#include "yaffs_attribs.h"
> +#include "yaffs_linux.h"
> +#include "yaffs_mtdif.h"
> +#include "yaffs_mtdif1.h"
> +#include "yaffs_mtdif2.h"
> +
> +unsigned int yaffs_trace_mask = YAFFS_TRACE_BAD_BLOCKS | YAFFS_TRACE_ALWAYS;
> +unsigned int yaffs_wr_attempts = YAFFS_WR_ATTEMPTS;
> +unsigned int yaffs_auto_checkpoint = 1;
> +unsigned int yaffs_gc_control = 1;
> +unsigned int yaffs_bg_enable = 1;

Some of these can be static I think.

> +
> +/* Module Parameters */
> +module_param(yaffs_trace_mask, uint, 0644);
> +module_param(yaffs_wr_attempts, uint, 0644);
> +module_param(yaffs_auto_checkpoint, uint, 0644);
> +module_param(yaffs_gc_control, uint, 0644);
> +module_param(yaffs_bg_enable, uint, 0644);
> +
> +#define yaffs_devname(sb, buf)	bdevname(sb->s_bdev, buf)
> +
> +static uint32_t YCALCBLOCKS(uint64_t partition_size, uint32_t block_size)

Lower case names for functions. Types should also be u32 and u64.

> +{
> +	uint64_t result = partition_size;
> +
> +	do_div(result, block_size);
> +	return (uint32_t) result;
> +}
> +
> +#define yaffs_inode_to_obj_lv(iptr) ((iptr)->i_private)
> +#define yaffs_inode_to_obj(iptr)\
> +	((struct yaffs_obj *)(yaffs_inode_to_obj_lv(iptr)))
> +#define yaffs_dentry_to_obj(dptr) yaffs_inode_to_obj((dptr)->d_inode)
> +#define yaffs_super_to_dev(sb)	((struct yaffs_dev *)sb->s_fs_info)
> +
> +#define update_dir_time(dir) do {\
> +			(dir)->i_ctime = (dir)->i_mtime = CURRENT_TIME; \
> +		} while (0)

Any reason this can't be a function. Possibly static inline?

> +
> +
> +static unsigned yaffs_gc_control_callback(struct yaffs_dev *dev)
> +{
> +	return yaffs_gc_control;
> +}
> +
> +static void yaffs_gross_lock(struct yaffs_dev *dev)
> +{
> +	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locking %p", current);
> +	mutex_lock(&(yaffs_dev_to_lc(dev)->gross_lock));
> +	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locked %p", current);
> +}
> +
> +static void yaffs_gross_unlock(struct yaffs_dev *dev)
> +{
> +	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs unlocking %p", current);
> +	mutex_unlock(&(yaffs_dev_to_lc(dev)->gross_lock));
> +}
> +
> +static void yaffs_fill_inode_from_obj(struct inode *inode,
> +				      struct yaffs_obj *obj);
> +
> +static struct inode *yaffs_iget(struct super_block *sb, unsigned long ino)
> +{
> +	struct inode *inode;
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_iget for %lu", ino);
> +
> +	inode = iget_locked(sb, ino);
> +	if (!inode)
> +		return ERR_PTR(-ENOMEM);
> +	if (!(inode->i_state & I_NEW))
> +		return inode;
> +
> +	/* NB This is called as a side effect of other functions, but
> +	 * we had to release the lock to prevent deadlocks, so
> +	 * need to lock again.
> +	 */
> +
> +	yaffs_gross_lock(dev);
> +
> +	obj = yaffs_find_by_number(dev, inode->i_ino);
> +	yaffs_fill_inode_from_obj(inode, obj);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	unlock_new_inode(inode);
> +	return inode;
> +}
> +
> +struct inode *yaffs_get_inode(struct super_block *sb, int mode, int dev,
> +			      struct yaffs_obj *obj)
> +{
> +	struct inode *inode;
> +
> +	if (!sb) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_get_inode for NULL super_block!!");
> +		return NULL;
> +
> +	}
> +
> +	if (!obj) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_get_inode for NULL object!!");
> +		return NULL;
> +
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_get_inode for object %d",
> +		obj->obj_id);
> +
> +	inode = yaffs_iget(sb, obj->obj_id);
> +	if (IS_ERR(inode))
> +		return NULL;

Should this function not propagate the error up by returning PTR_ERR also?

> +
> +	/* NB Side effect: iget calls back to yaffs_read_inode(). */
> +	/* iget also increments the inode's i_count */
> +	/* NB You can't be holding gross_lock or deadlock will happen! */
> +
> +	return inode;
> +}
> +
> +static int yaffs_mknod(struct inode *dir, struct dentry *dentry, int mode,
> +		       dev_t rdev)
> +{
> +	struct inode *inode;
> +	struct yaffs_obj *obj = NULL;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *parent = yaffs_inode_to_obj(dir);
> +	int error = -ENOSPC;
> +	uid_t uid = current->cred->fsuid;
> +	gid_t gid =
> +	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
> +
> +	if ((dir->i_mode & S_ISGID) && S_ISDIR(mode))
> +		mode |= S_ISGID;
> +
> +	if (parent) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_mknod: parent object %d type %d",
> +			parent->obj_id, parent->variant_type);
> +	} else {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_mknod: could not get parent object");
> +		return -EPERM;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_mknod: making oject for %s, mode %x dev %x",
> +		dentry->d_name.name, mode, rdev);
> +
> +	dev = parent->my_dev;
> +
> +	yaffs_gross_lock(dev);

Possibly a start to removing the gross locking, or replacing it with
more fine grained locking is to push it down into each of the creation
functions below.

> +
> +	switch (mode & S_IFMT) {
> +	default:
> +		/* Special (socket, fifo, device...) */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making special");
> +		obj =
> +		    yaffs_create_special(parent, dentry->d_name.name, mode, uid,
> +					 gid, old_encode_dev(rdev));
> +		break;
> +	case S_IFREG:		/* file          */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making file");
> +		obj = yaffs_create_file(parent, dentry->d_name.name, mode, uid,
> +					gid);
> +		break;
> +	case S_IFDIR:		/* directory */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making directory");
> +		obj = yaffs_create_dir(parent, dentry->d_name.name, mode,
> +				       uid, gid);
> +		break;
> +	case S_IFLNK:		/* symlink */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making symlink");
> +		obj = NULL;	/* Do we ever get here? */
> +		break;
> +	}
> +
> +	/* Can not call yaffs_get_inode() with gross lock held */
> +	yaffs_gross_unlock(dev);
> +
> +	if (obj) {
> +		inode = yaffs_get_inode(dir->i_sb, mode, rdev, obj);

if (!inode)?

> +		d_instantiate(dentry, inode);
> +		update_dir_time(dir);
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_mknod created object %d count = %d",
> +			obj->obj_id, atomic_read(&inode->i_count));
> +		error = 0;
> +		yaffs_fill_inode_from_obj(dir, parent);
> +	} else {
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod failed making object");
> +		error = -ENOMEM;
> +	}
> +
> +	return error;
> +}
> +
> +static int yaffs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
> +{
> +	return yaffs_mknod(dir, dentry, mode | S_IFDIR, 0);
> +}
> +
> +static int yaffs_create(struct inode *dir, struct dentry *dentry, int mode,
> +			struct nameidata *n)
> +{
> +	return yaffs_mknod(dir, dentry, mode | S_IFREG, 0);
> +}
> +
> +static int yaffs_link(struct dentry *old_dentry, struct inode *dir,
> +		      struct dentry *dentry)
> +{
> +	struct inode *inode = old_dentry->d_inode;
> +	struct yaffs_obj *obj = NULL;
> +	struct yaffs_obj *link = NULL;
> +	struct yaffs_dev *dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_link");
> +
> +	obj = yaffs_inode_to_obj(inode);
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	if (!S_ISDIR(inode->i_mode))	/* Don't link directories */
> +		link =
> +		    yaffs_link_obj(yaffs_inode_to_obj(dir), dentry->d_name.name,
> +				   obj);
> +
> +	if (link) {
> +		old_dentry->d_inode->i_nlink = yaffs_get_obj_link_count(obj);
> +		d_instantiate(dentry, old_dentry->d_inode);
> +		atomic_inc(&old_dentry->d_inode->i_count);
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_link link count %d i_count %d",
> +			old_dentry->d_inode->i_nlink,
> +			atomic_read(&old_dentry->d_inode->i_count));
> +	}
> +
> +	yaffs_gross_unlock(dev);
> +
> +	if (link) {
> +		update_dir_time(dir);
> +		return 0;
> +	}
> +
> +	return -EPERM;

I would change this to:

	if (!link)
		return -EPERM;

	update_dir_time(dir);
	return 0;

To make the successful path more obvious.

> +}
> +
> +static int yaffs_symlink(struct inode *dir, struct dentry *dentry,
> +			 const char *symname)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	uid_t uid = current->cred->fsuid;
> +	gid_t gid =
> +	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_symlink");
> +
> +	dev = yaffs_inode_to_obj(dir)->my_dev;
> +	yaffs_gross_lock(dev);
> +	obj = yaffs_create_symlink(yaffs_inode_to_obj(dir), dentry->d_name.name,
> +				   S_IFLNK | S_IRWXUGO, uid, gid, symname);
> +	yaffs_gross_unlock(dev);
> +
> +	if (obj) {
> +		struct inode *inode;
> +
> +		inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
> +		d_instantiate(dentry, inode);
> +		update_dir_time(dir);
> +		yaffs_trace(YAFFS_TRACE_OS, "symlink created OK");
> +		return 0;
> +	} else {
> +		yaffs_trace(YAFFS_TRACE_OS, "symlink not created");
> +	}
> +
> +	return -ENOMEM;

Again, make the successful path more obvious:

	if (!obj) {
		yaffs_trace(YAFFS_TRACE_OS, "symlink not created");
		return -ENOMEM;
	}

	...
	return 0;

> +}
> +
> +static struct dentry *yaffs_lookup(struct inode *dir, struct dentry *dentry,
> +				   struct nameidata *n)
> +{
> +	struct yaffs_obj *obj;
> +	struct inode *inode = NULL;
> +	struct yaffs_dev *dev = yaffs_inode_to_obj(dir)->my_dev;
> +
> +	if (current != yaffs_dev_to_lc(dev)->readdir_process)
> +		yaffs_gross_lock(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_lookup for %d:%s",
> +		yaffs_inode_to_obj(dir)->obj_id, dentry->d_name.name);
> +
> +	obj = yaffs_find_by_name(yaffs_inode_to_obj(dir), dentry->d_name.name);
> +
> +	obj = yaffs_get_equivalent_obj(obj);	/* in case it was a hardlink */
> +
> +	/* Can't hold gross lock when calling yaffs_get_inode() */
> +	if (current != yaffs_dev_to_lc(dev)->readdir_process)
> +		yaffs_gross_unlock(dev);
> +
> +	if (obj) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_lookup found %d", obj->obj_id);
> +
> +		inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
> +
> +		if (inode) {
> +			yaffs_trace(YAFFS_TRACE_OS, "yaffs_loookup dentry");
> +			d_add(dentry, inode);
> +			/* return dentry; */
> +			return NULL;

This comment seems inaccurate.

> +		}
> +
> +	} else {
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_lookup not found");
> +
> +	}
> +
> +	d_add(dentry, inode);
> +
> +	return NULL;

I can't even tell what the success path is here :-/.

> +}
> +
> +static int yaffs_unlink(struct inode *dir, struct dentry *dentry)
> +{
> +	int ret_val;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_unlink %d:%s",
> +		(int)(dir->i_ino), dentry->d_name.name);
> +	obj = yaffs_inode_to_obj(dir);
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	ret_val = yaffs_unlinker(obj, dentry->d_name.name);
> +
> +	if (ret_val == YAFFS_OK) {
> +		dentry->d_inode->i_nlink--;
> +		dir->i_version++;
> +		yaffs_gross_unlock(dev);
> +		mark_inode_dirty(dentry->d_inode);
> +		update_dir_time(dir);
> +		return 0;
> +	}
> +	yaffs_gross_unlock(dev);
> +	return -ENOTEMPTY;
> +}
> +
> +static int yaffs_sync_object(struct file *file, int datasync)
> +{
> +
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	struct dentry *dentry = file->f_path.dentry;
> +
> +	obj = yaffs_dentry_to_obj(dentry);
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC, "yaffs_sync_object");
> +	yaffs_gross_lock(dev);
> +	yaffs_flush_file(obj, 1, datasync);
> +	yaffs_gross_unlock(dev);
> +	return 0;
> +}
> +/*
> + * The VFS layer already does all the dentry stuff for rename.
> + *
> + * NB: POSIX says you can rename an object over an old object of the same name
> + */
> +static int yaffs_rename(struct inode *old_dir, struct dentry *old_dentry,
> +			struct inode *new_dir, struct dentry *new_dentry)
> +{
> +	struct yaffs_dev *dev;
> +	int ret_val = YAFFS_FAIL;
> +	struct yaffs_obj *target;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_rename");
> +	dev = yaffs_inode_to_obj(old_dir)->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	/* Check if the target is an existing directory that is not empty. */
> +	target = yaffs_find_by_name(yaffs_inode_to_obj(new_dir),
> +				    new_dentry->d_name.name);
> +
> +	if (target && target->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY &&
> +	    !list_empty(&target->variant.dir_variant.children)) {
> +
> +		yaffs_trace(YAFFS_TRACE_OS, "target is non-empty dir");
> +
> +		ret_val = YAFFS_FAIL;
> +	} else {
> +		/* Now does unlinking internally using shadowing mechanism */
> +		yaffs_trace(YAFFS_TRACE_OS, "calling yaffs_rename_obj");
> +
> +		ret_val = yaffs_rename_obj(yaffs_inode_to_obj(old_dir),
> +					   old_dentry->d_name.name,
> +					   yaffs_inode_to_obj(new_dir),
> +					   new_dentry->d_name.name);
> +	}
> +	yaffs_gross_unlock(dev);
> +
> +	if (ret_val == YAFFS_OK) {
> +		if (target) {
> +			new_dentry->d_inode->i_nlink--;
> +			mark_inode_dirty(new_dentry->d_inode);
> +		}
> +
> +		update_dir_time(old_dir);
> +		if (old_dir != new_dir)
> +			update_dir_time(new_dir);
> +		return 0;
> +	} else {
> +		return -ENOTEMPTY;
> +	}

	if (ret_val != YAFFS_OK)
		return -ENOTEMPTY;

	...
	
> +}
> +
> +static int yaffs_setattr(struct dentry *dentry, struct iattr *attr)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error = 0;
> +	struct yaffs_dev *dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_setattr of object %d",
> +		yaffs_inode_to_obj(inode)->obj_id);
> +
> +	/* Fail if a requested resize >= 2GB */
> +	if (attr->ia_valid & ATTR_SIZE && (attr->ia_size >> 31))
> +		error = -EINVAL;

Here you set the error and then do nothing for the rest of the function
because of all the if (error == 0) checks. Either return immediately
here, or use a goto to get to the end of the function and then remove
all the checks.

> +
> +	if (error == 0)
> +		error = inode_change_ok(inode, attr);
> +	if (error == 0) {
> +		int result;
> +		if (!error) {
> +			setattr_copy(inode, attr);
> +			yaffs_trace(YAFFS_TRACE_OS, "inode_setattr called");
> +			if (attr->ia_valid & ATTR_SIZE) {
> +				truncate_setsize(inode, attr->ia_size);
> +				inode->i_blocks = (inode->i_size + 511) >> 9;
> +			}
> +		}
> +		dev = yaffs_inode_to_obj(inode)->my_dev;
> +		if (attr->ia_valid & ATTR_SIZE) {
> +			yaffs_trace(YAFFS_TRACE_OS, "resize to %d(%x)",
> +					   (int)(attr->ia_size),
> +					   (int)(attr->ia_size));
> +		}
> +		yaffs_gross_lock(dev);
> +		result = yaffs_set_attribs(yaffs_inode_to_obj(inode), attr);
> +		if (result == YAFFS_OK)
> +			error = 0;
> +		else
> +			error = -EPERM;
> +		yaffs_gross_unlock(dev);
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +#ifdef CONFIG_YAFFS_XATTR
> +static int yaffs_setxattr(struct dentry *dentry, const char *name,
> +		   const void *value, size_t size, int flags)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error = 0;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr of object %d", obj->obj_id);
> +
> +	if (error == 0) {
> +		int result;
> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		result = yaffs_set_xattrib(obj, name, value, size, flags);
> +		if (result == YAFFS_OK)
> +			error = 0;

error is already zero. error and result are also basically the same
thing, I don't think you need both variables.

> +		else if (result < 0)
> +			error = result;
> +		yaffs_gross_unlock(dev);
> +	}
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +static ssize_t yaffs_getxattr(struct dentry *dentry, const char *name,
> +				void *buff, size_t size)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error = 0;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_getxattr \"%s\" from object %d",
> +		name, obj->obj_id);
> +
> +	if (error == 0) {

Umm, error is explicitly initialised to zero?

> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		error = yaffs_get_xattrib(obj, name, buff, size);
> +		yaffs_gross_unlock(dev);
> +	}
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_getxattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +static int yaffs_removexattr(struct dentry *dentry, const char *name)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error = 0;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_removexattr of object %d", obj->obj_id);
> +
> +	if (error == 0) {

Again, error is guaranteed to be zero here.

> +		int result;
> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		result = yaffs_remove_xattrib(obj, name);
> +		if (result == YAFFS_OK)
> +			error = 0;

and here.

> +		else if (result < 0)
> +			error = result;
> +		yaffs_gross_unlock(dev);
> +	}
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_removexattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +static ssize_t yaffs_listxattr(struct dentry *dentry, char *buff, size_t size)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error = 0;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_listxattr of object %d", obj->obj_id);
> +
> +	if (error == 0) {

and here.

> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		error = yaffs_list_xattrib(obj, buff, size);
> +		yaffs_gross_unlock(dev);
> +	}
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_listxattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +#endif
> +
> +static const struct inode_operations yaffs_dir_inode_operations = {
> +	.create = yaffs_create,
> +	.lookup = yaffs_lookup,
> +	.link = yaffs_link,
> +	.unlink = yaffs_unlink,
> +	.symlink = yaffs_symlink,
> +	.mkdir = yaffs_mkdir,
> +	.rmdir = yaffs_unlink,
> +	.mknod = yaffs_mknod,
> +	.rename = yaffs_rename,
> +	.setattr = yaffs_setattr,
> +#ifdef CONFIG_YAFFS_XATTR
> +	.setxattr = yaffs_setxattr,
> +	.getxattr = yaffs_getxattr,
> +	.listxattr = yaffs_listxattr,
> +	.removexattr = yaffs_removexattr,
> +#endif
> +};
> +/*-----------------------------------------------------------------*/
> +/* Directory search context allows us to unlock access to yaffs during
> + * filldir without causing problems with the directory being modified.
> + * This is similar to the tried and tested mechanism used in yaffs direct.
> + *
> + * A search context iterates along a doubly linked list of siblings in the
> + * directory. If the iterating object is deleted then this would corrupt
> + * the list iteration, likely causing a crash. The search context avoids
> + * this by using the remove_obj_fn to move the search context to the
> + * next object before the object is deleted.
> + *
> + * Many readdirs (and thus seach conexts) may be alive simulateously so
> + * each struct yaffs_dev has a list of these.
> + *
> + * A seach context lives for the duration of a readdir.
> + *
> + * All these functions must be called while yaffs is locked.
> + */
> +
> +struct yaffs_search_context {
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *dir_obj;
> +	struct yaffs_obj *next_return;
> +	struct list_head others;
> +};
> +
> +/*
> + * yaffs_new_search() creates a new search context, initialises it and
> + * adds it to the device's search context list.
> + *
> + * Called at start of readdir.
> + */
> +static struct yaffs_search_context *yaffs_new_search(struct yaffs_obj *dir)
> +{
> +	struct yaffs_dev *dev = dir->my_dev;
> +	struct yaffs_search_context *sc =
> +	    kmalloc(sizeof(struct yaffs_search_context), GFP_NOFS);
> +
> +	if (sc) {

if (!sc)
	return NULL;

Remove indentation of normal executation path :-).

> +		sc->dir_obj = dir;
> +		sc->dev = dev;
> +		if (list_empty(&sc->dir_obj->variant.dir_variant.children))
> +			sc->next_return = NULL;
> +		else
> +			sc->next_return =
> +			    list_entry(dir->variant.dir_variant.children.next,
> +				       struct yaffs_obj, siblings);
> +		INIT_LIST_HEAD(&sc->others);
> +		list_add(&sc->others, &(yaffs_dev_to_lc(dev)->search_contexts));
> +	}
> +	return sc;
> +}
> +
> +/*
> + * yaffs_search_end() disposes of a search context and cleans up.
> + */
> +static void yaffs_search_end(struct yaffs_search_context *sc)
> +{
> +	if (sc) {
> +		list_del(&sc->others);
> +		kfree(sc);
> +	}
> +}
> +
> +/*
> + * yaffs_search_advance() moves a search context to the next object.
> + * Called when the search iterates or when an object removal causes
> + * the search context to be moved to the next object.
> + */
> +static void yaffs_search_advance(struct yaffs_search_context *sc)
> +{
> +	if (!sc)
> +		return;
> +
> +	if (sc->next_return == NULL ||
> +	    list_empty(&sc->dir_obj->variant.dir_variant.children))
> +		sc->next_return = NULL;
> +	else {
> +		struct list_head *next = sc->next_return->siblings.next;
> +
> +		if (next == &sc->dir_obj->variant.dir_variant.children)
> +			sc->next_return = NULL;	/* end of list */
> +		else
> +			sc->next_return =
> +			    list_entry(next, struct yaffs_obj, siblings);
> +	}
> +}
> +
> +/*
> + * yaffs_remove_obj_callback() is called when an object is unlinked.
> + * We check open search contexts and advance any which are currently
> + * on the object being iterated.
> + */
> +static void yaffs_remove_obj_callback(struct yaffs_obj *obj)
> +{
> +
> +	struct list_head *i;
> +	struct yaffs_search_context *sc;
> +	struct list_head *search_contexts =
> +	    &(yaffs_dev_to_lc(obj->my_dev)->search_contexts);
> +
> +	/* Iterate through the directory search contexts.
> +	 * If any are currently on the object being removed, then advance
> +	 * the search context to the next object to prevent a hanging pointer.
> +	 */
> +	list_for_each(i, search_contexts) {
> +		sc = list_entry(i, struct yaffs_search_context, others);

	list_for_each_entry(i, search_contexts, others)

> +		if (sc->next_return == obj)
> +			yaffs_search_advance(sc);
> +	}
> +
> +}
> +
> +static int yaffs_readdir(struct file *f, void *dirent, filldir_t filldir)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	struct yaffs_search_context *sc;
> +	struct inode *inode = f->f_dentry->d_inode;
> +	unsigned long offset, curoffs;
> +	struct yaffs_obj *l;
> +	int ret_val = 0;
> +	char name[YAFFS_MAX_NAME_LENGTH + 1];
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_dev_to_lc(dev)->readdir_process = current;
> +
> +	offset = f->f_pos;
> +
> +	sc = yaffs_new_search(obj);
> +	if (!sc) {
> +		ret_val = -ENOMEM;
> +		goto out;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_readdir: starting at %d", (int)offset);
> +
> +	if (offset == 0) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_readdir: entry . ino %d",
> +			(int)inode->i_ino);
> +		yaffs_gross_unlock(dev);
> +		if (filldir(dirent, ".", 1, offset, inode->i_ino, DT_DIR) < 0) {
> +			yaffs_gross_lock(dev);
> +			goto out;

This is a bit ugly. Probably cleaner to have separate exit labels for
the case where you don't need the unlock.

What is gross lock actually protecting here? Can it be more fine grained?

> +		}
> +		yaffs_gross_lock(dev);
> +		offset++;
> +		f->f_pos++;
> +	}
> +	if (offset == 1) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_readdir: entry .. ino %d",
> +			(int)f->f_dentry->d_parent->d_inode->i_ino);
> +		yaffs_gross_unlock(dev);
> +		if (filldir(dirent, "..", 2, offset,
> +			    f->f_dentry->d_parent->d_inode->i_ino,
> +			    DT_DIR) < 0) {
> +			yaffs_gross_lock(dev);
> +			goto out;
> +		}
> +		yaffs_gross_lock(dev);
> +		offset++;
> +		f->f_pos++;
> +	}
> +
> +	curoffs = 1;
> +
> +	/* If the directory has changed since the open or last call to
> +	   readdir, rewind to after the 2 canned entries. */
> +	if (f->f_version != inode->i_version) {
> +		offset = 2;
> +		f->f_pos = offset;
> +		f->f_version = inode->i_version;
> +	}
> +
> +	while (sc->next_return) {
> +		curoffs++;
> +		l = sc->next_return;
> +		if (curoffs >= offset) {
> +			int this_inode = yaffs_get_obj_inode(l);
> +			int this_type = yaffs_get_obj_type(l);
> +
> +			yaffs_get_obj_name(l, name, YAFFS_MAX_NAME_LENGTH + 1);
> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"yaffs_readdir: %s inode %d",
> +				name, yaffs_get_obj_inode(l));
> +
> +			yaffs_gross_unlock(dev);
> +
> +			if (filldir(dirent,
> +				    name,
> +				    strlen(name),
> +				    offset, this_inode, this_type) < 0) {
> +				yaffs_gross_lock(dev);
> +				goto out;
> +			}
> +
> +			yaffs_gross_lock(dev);
> +
> +			offset++;
> +			f->f_pos++;
> +		}
> +		yaffs_search_advance(sc);
> +	}
> +
> +out:
> +	yaffs_search_end(sc);
> +	yaffs_dev_to_lc(dev)->readdir_process = NULL;
> +	yaffs_gross_unlock(dev);
> +
> +	return ret_val;
> +}
> +
> +static const struct file_operations yaffs_dir_operations = {
> +	.read = generic_read_dir,
> +	.readdir = yaffs_readdir,
> +	.fsync = yaffs_sync_object,
> +	.llseek = generic_file_llseek,
> +};
> +
> +
> +
> +static int yaffs_file_flush(struct file *file, fl_owner_t id)
> +{
> +	struct yaffs_obj *obj = yaffs_dentry_to_obj(file->f_dentry);
> +	struct yaffs_dev *dev = obj->my_dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_file_flush object %d (%s)",
> +		obj->obj_id, obj->dirty ? "dirty" : "clean");
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_flush_file(obj, 1, 0);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	return 0;
> +}
> +
> +static const struct file_operations yaffs_file_operations = {
> +	.read = do_sync_read,
> +	.write = do_sync_write,
> +	.aio_read = generic_file_aio_read,
> +	.aio_write = generic_file_aio_write,
> +	.mmap = generic_file_mmap,
> +	.flush = yaffs_file_flush,
> +	.fsync = yaffs_sync_object,
> +	.splice_read = generic_file_splice_read,
> +	.splice_write = generic_file_splice_write,
> +	.llseek = generic_file_llseek,
> +};
> +
> +
> +/* ExportFS support */
> +static struct inode *yaffs2_nfs_get_inode(struct super_block *sb, uint64_t ino,
> +					  uint32_t generation)
> +{
> +	return yaffs_iget(sb, ino);
> +}
> +
> +static struct dentry *yaffs2_fh_to_dentry(struct super_block *sb,
> +					  struct fid *fid, int fh_len,
> +					  int fh_type)
> +{
> +	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
> +				    yaffs2_nfs_get_inode);
> +}
> +
> +static struct dentry *yaffs2_fh_to_parent(struct super_block *sb,
> +					  struct fid *fid, int fh_len,
> +					  int fh_type)
> +{
> +	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
> +				    yaffs2_nfs_get_inode);
> +}
> +
> +struct dentry *yaffs2_get_parent(struct dentry *dentry)
> +{
> +
> +	struct super_block *sb = dentry->d_inode->i_sb;
> +	struct dentry *parent = ERR_PTR(-ENOENT);
> +	struct inode *inode;
> +	unsigned long parent_ino;
> +	struct yaffs_obj *d_obj;
> +	struct yaffs_obj *parent_obj;
> +
> +	d_obj = yaffs_inode_to_obj(dentry->d_inode);
> +
> +	if (d_obj) {

if (!d_obj)
	return ERR_PTR(-ENOENT);

You can use goto fail; if you want single return point.

> +		parent_obj = d_obj->parent;
> +		if (parent_obj) {
> +			parent_ino = yaffs_get_obj_inode(parent_obj);
> +			inode = yaffs_iget(sb, parent_ino);
> +
> +			if (IS_ERR(inode)) {
> +				parent = ERR_CAST(inode);

Return/goto directly from here. Makes the normal path easier to follow.

> +			} else {
> +				parent = d_obtain_alias(inode);
> +				if (!IS_ERR(parent)) {
> +					parent = ERR_PTR(-ENOMEM);
> +					iput(inode);
> +				}
> +			}
> +		}
> +	}
> +	return parent;
> +}
> +
> +/* Just declare a zero structure as a NULL value implies
> + * using the default functions of exportfs.
> + */
> +
> +static struct export_operations yaffs_export_ops = {
> +	.fh_to_dentry = yaffs2_fh_to_dentry,
> +	.fh_to_parent = yaffs2_fh_to_parent,
> +	.get_parent = yaffs2_get_parent,
> +};
> +
> +
> +/*-----------------------------------------------------------------*/
> +
> +static int yaffs_readlink(struct dentry *dentry, char __user * buffer,
> +			  int buflen)
> +{
> +	unsigned char *alias;
> +	int ret;
> +	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
> +
> +	yaffs_gross_unlock(dev);

What does gross lock protect here? Is it safe to use/free alias outside
of the lock below?

> +
> +	if (!alias)
> +		return -ENOMEM;
> +
> +	ret = vfs_readlink(dentry, buffer, buflen, alias);
> +	kfree(alias);
> +	return ret;
> +}
> +
> +static void *yaffs_follow_link(struct dentry *dentry, struct nameidata *nd)
> +{
> +	unsigned char *alias;
> +	void *ret;
> +	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
> +	yaffs_gross_unlock(dev);
> +
> +	if (!alias) {
> +		ret = ERR_PTR(-ENOMEM);
> +		goto out;
> +	}
> +
> +	nd_set_link(nd, alias);
> +	ret = (void *)alias;

Shoudn't need the cast.

> +out:
> +	return ret;
> +}
> +
> +void yaffs_put_link(struct dentry *dentry, struct nameidata *nd, void *alias)
> +{
> +	kfree(alias);
> +}
> +
> +
> +static void yaffs_unstitch_obj(struct inode *inode, struct yaffs_obj *obj)
> +{
> +	/* Clear the association between the inode and
> +	 * the struct yaffs_obj.
> +	 */
> +	obj->my_inode = NULL;
> +	yaffs_inode_to_obj_lv(inode) = NULL;
> +
> +	/* If the object freeing was deferred, then the real
> +	 * free happens now.
> +	 * This should fix the inode inconsistency problem.
> +	 */
> +	yaffs_handle_defered_free(obj);
> +}
> +
> +/* yaffs_evict_inode combines into one operation what was previously done in
> + * yaffs_clear_inode() and yaffs_delete_inode()
> + *
> + */
> +static void yaffs_evict_inode(struct inode *inode)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	int deleteme = 0;
> +
> +	obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_evict_inode: ino %d, count %d %s",
> +		(int)inode->i_ino,
> +		atomic_read(&inode->i_count),
> +		obj ? "object exists" : "null object");
> +
> +	if (!inode->i_nlink && !is_bad_inode(inode))
> +		deleteme = 1;
> +	truncate_inode_pages(&inode->i_data, 0);
> +	end_writeback(inode);
> +
> +	if (deleteme && obj) {
> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		yaffs_del_obj(obj);
> +		yaffs_gross_unlock(dev);
> +	}
> +	if (obj) {
> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		yaffs_unstitch_obj(inode, obj);
> +		yaffs_gross_unlock(dev);
> +	}
> +
> +}
> +
> +static void yaffs_touch_super(struct yaffs_dev *dev)
> +{
> +	struct super_block *sb = yaffs_dev_to_lc(dev)->super;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_touch_super() sb = %p", sb);
> +	if (sb)
> +		sb->s_dirt = 1;
> +}
> +
> +static int yaffs_readpage_nolock(struct file *f, struct page *pg)
> +{
> +	/* Lifted from jffs2 */
> +
> +	struct yaffs_obj *obj;
> +	unsigned char *pg_buf;
> +	int ret;
> +	struct yaffs_dev *dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_readpage_nolock at %08x, size %08x",
> +		(unsigned)(pg->index << PAGE_CACHE_SHIFT),
> +		(unsigned)PAGE_CACHE_SIZE);
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	dev = obj->my_dev;
> +
> +	BUG_ON(!PageLocked(pg));
> +
> +	pg_buf = kmap(pg);
> +	/* FIXME: Can kmap fail? */

A warning at least?

> +
> +	yaffs_gross_lock(dev);
> +
> +	ret = yaffs_file_rd(obj, pg_buf,
> +			    pg->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	if (ret >= 0)
> +		ret = 0;
> +
> +	if (ret) {
> +		ClearPageUptodate(pg);
> +		SetPageError(pg);
> +	} else {
> +		SetPageUptodate(pg);
> +		ClearPageError(pg);
> +	}
> +
> +	flush_dcache_page(pg);
> +	kunmap(pg);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage_nolock done");
> +	return ret;
> +}
> +
> +static int yaffs_readpage_unlock(struct file *f, struct page *pg)
> +{
> +	int ret = yaffs_readpage_nolock(f, pg);
> +
> +	unlock_page(pg);
> +	return ret;
> +}
> +
> +static int yaffs_readpage(struct file *f, struct page *pg)
> +{
> +	int ret;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage");
> +	ret = yaffs_readpage_unlock(f, pg);
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage done");
> +	return ret;
> +}
> +
> +/* writepage inspired by/stolen from smbfs */
> +
> +static int yaffs_writepage(struct page *page, struct writeback_control *wbc)
> +{
> +	struct yaffs_dev *dev;
> +	struct address_space *mapping = page->mapping;
> +	struct inode *inode;
> +	unsigned long end_index;
> +	char *buffer;
> +	struct yaffs_obj *obj;
> +	int n_written = 0;
> +	unsigned n_bytes;
> +	loff_t i_size;
> +
> +	if (!mapping)
> +		BUG();
> +	inode = mapping->host;
> +	if (!inode)
> +		BUG();
> +	i_size = i_size_read(inode);
> +
> +	end_index = i_size >> PAGE_CACHE_SHIFT;
> +
> +	if (page->index < end_index)
> +		n_bytes = PAGE_CACHE_SIZE;
> +	else {
> +		n_bytes = i_size & (PAGE_CACHE_SIZE - 1);
> +
> +		if (page->index > end_index || !n_bytes) {
> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"yaffs_writepage at %08x, inode size = %08x!!!",
> +				(unsigned)(page->index << PAGE_CACHE_SHIFT),
> +				(unsigned)inode->i_size);
> +			yaffs_trace(YAFFS_TRACE_OS,
> +			  "                -> don't care!!");
> +
> +			zero_user_segment(page, 0, PAGE_CACHE_SIZE);
> +			set_page_writeback(page);
> +			unlock_page(page);
> +			end_page_writeback(page);
> +			return 0;
> +		}
> +	}
> +
> +	if (n_bytes != PAGE_CACHE_SIZE)
> +		zero_user_segment(page, n_bytes, PAGE_CACHE_SIZE);
> +
> +	get_page(page);
> +
> +	buffer = kmap(page);

if (!buffer)?

> +
> +	obj = yaffs_inode_to_obj(inode);
> +	dev = obj->my_dev;
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_writepage at %08x, size %08x",
> +		(unsigned)(page->index << PAGE_CACHE_SHIFT), n_bytes);
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"writepag0: obj = %05x, ino = %05x",
> +		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
> +
> +	n_written = yaffs_wr_file(obj, buffer,
> +				  page->index << PAGE_CACHE_SHIFT, n_bytes, 0);
> +
> +	yaffs_touch_super(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"writepag1: obj = %05x, ino = %05x",
> +		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	kunmap(page);
> +	set_page_writeback(page);
> +	unlock_page(page);
> +	end_page_writeback(page);
> +	put_page(page);
> +
> +	return (n_written == n_bytes) ? 0 : -ENOSPC;
> +}
> +
> +/* Space holding and freeing is done to ensure we have space available for
> + * write_begin/end.
> + * For now we just assume few parallel writes and check against a small
> + * number.
> + * Todo: need to do this with a counter to handle parallel reads better
> + */
> +
> +static ssize_t yaffs_hold_space(struct file *f)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	int n_free_chunks;
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	n_free_chunks = yaffs_get_n_free_chunks(dev);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	return (n_free_chunks > 20) ? 1 : 0;
> +}
> +
> +static void yaffs_release_space(struct file *f)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_gross_unlock(dev);

What does this lock/unlock do?

> +}
> +
> +static int yaffs_write_begin(struct file *filp, struct address_space *mapping,
> +			     loff_t pos, unsigned len, unsigned flags,
> +			     struct page **pagep, void **fsdata)
> +{
> +	struct page *pg = NULL;
> +	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
> +	int ret = 0;
> +	int space_held = 0;
> +
> +	/* Get a page */
> +	pg = grab_cache_page_write_begin(mapping, index, flags);
> +
> +	*pagep = pg;
> +	if (!pg) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"start yaffs_write_begin index %d(%x) uptodate %d",
> +		(int)index, (int)index, PageUptodate(pg) ? 1 : 0);
> +
> +	/* Get fs space */
> +	space_held = yaffs_hold_space(filp);
> +
> +	if (!space_held) {
> +		ret = -ENOSPC;
> +		goto out;
> +	}
> +
> +	/* Update page if required */
> +
> +	if (!PageUptodate(pg))
> +		ret = yaffs_readpage_nolock(filp, pg);
> +
> +	if (ret)
> +		goto out;
> +
> +	/* Happy path return */
> +	yaffs_trace(YAFFS_TRACE_OS, "end yaffs_write_begin - ok");
> +
> +	return 0;
> +
> +out:
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"end yaffs_write_begin fail returning %d", ret);
> +	if (space_held)
> +		yaffs_release_space(filp);
> +	if (pg) {
> +		unlock_page(pg);
> +		page_cache_release(pg);
> +	}
> +	return ret;
> +}
> +
> +static ssize_t yaffs_file_write(struct file *f, const char *buf, size_t n,
> +				loff_t *pos)
> +{
> +	struct yaffs_obj *obj;
> +	int n_written, ipos;
> +	struct inode *inode;
> +	struct yaffs_dev *dev;
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	if (!obj) {
> +		/* This should not happen */
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_file_write: hey obj is null!");
> +		return -EINVAL;
> +	}
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	inode = f->f_dentry->d_inode;
> +
> +	if (!S_ISBLK(inode->i_mode) && f->f_flags & O_APPEND)
> +		ipos = inode->i_size;
> +	else
> +		ipos = *pos;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_file_write about to write writing %u(%x) bytes to object %d at %d(%x)",
> +		(unsigned)n, (unsigned)n, obj->obj_id, ipos, ipos);
> +
> +	n_written = yaffs_wr_file(obj, buf, ipos, n, 0);
> +
> +	yaffs_touch_super(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_file_write: %d(%x) bytes written",
> +		(unsigned)n, (unsigned)n);
> +
> +	if (n_written > 0) {
> +		ipos += n_written;
> +		*pos = ipos;
> +		if (ipos > inode->i_size) {
> +			inode->i_size = ipos;
> +			inode->i_blocks = (ipos + 511) >> 9;
> +
> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"yaffs_file_write size updated to %d bytes, %d blocks",
> +				ipos, (int)(inode->i_blocks));
> +		}
> +	}
> +	yaffs_gross_unlock(dev);
> +	return (n_written == 0) && (n > 0) ? -ENOSPC : n_written;
> +}
> +
> +static int yaffs_write_end(struct file *filp, struct address_space *mapping,
> +			   loff_t pos, unsigned len, unsigned copied,
> +			   struct page *pg, void *fsdadata)
> +{
> +	int ret = 0;
> +	void *addr, *kva;
> +	uint32_t offset_into_page = pos & (PAGE_CACHE_SIZE - 1);
> +
> +	kva = kmap(pg);
> +	addr = kva + offset_into_page;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_write_end addr %p pos %x n_bytes %d",
> +		addr, (unsigned)pos, copied);
> +
> +	ret = yaffs_file_write(filp, addr, copied, &pos);
> +
> +	if (ret != copied) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_write_end not same size ret %d  copied %d",
> +			ret, copied);
> +		SetPageError(pg);
> +	}
> +
> +	kunmap(pg);
> +
> +	yaffs_release_space(filp);
> +	unlock_page(pg);
> +	page_cache_release(pg);
> +	return ret;
> +}
> +
> +static int yaffs_statfs(struct dentry *dentry, struct kstatfs *buf)
> +{
> +	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
> +	struct super_block *sb = dentry->d_sb;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_statfs");
> +
> +	yaffs_gross_lock(dev);
> +
> +	buf->f_type = YAFFS_MAGIC;
> +	buf->f_bsize = sb->s_blocksize;
> +	buf->f_namelen = 255;
> +
> +	if (dev->data_bytes_per_chunk & (dev->data_bytes_per_chunk - 1)) {
> +		/* Do this if chunk size is not a power of 2 */
> +
> +		uint64_t bytes_in_dev;
> +		uint64_t bytes_free;

u64?

> +
> +		bytes_in_dev =
> +		    ((uint64_t)
> +		     ((dev->param.end_block - dev->param.start_block +
> +		       1))) * ((uint64_t) (dev->param.chunks_per_block *
> +					   dev->data_bytes_per_chunk));
> +
> +		do_div(bytes_in_dev, sb->s_blocksize);
> +			/* bytes_in_dev becomes the number of blocks */
> +		buf->f_blocks = bytes_in_dev;
> +
> +		bytes_free = ((uint64_t) (yaffs_get_n_free_chunks(dev))) *
> +		    ((uint64_t) (dev->data_bytes_per_chunk));
> +
> +		do_div(bytes_free, sb->s_blocksize);
> +
> +		buf->f_bfree = bytes_free;
> +
> +	} else if (sb->s_blocksize > dev->data_bytes_per_chunk) {
> +
> +		buf->f_blocks =
> +		    (dev->param.end_block - dev->param.start_block + 1) *
> +		    dev->param.chunks_per_block /
> +		    (sb->s_blocksize / dev->data_bytes_per_chunk);
> +		buf->f_bfree =
> +		    yaffs_get_n_free_chunks(dev) /
> +		    (sb->s_blocksize / dev->data_bytes_per_chunk);
> +	} else {
> +		buf->f_blocks =
> +		    (dev->param.end_block - dev->param.start_block + 1) *
> +		    dev->param.chunks_per_block *
> +		    (dev->data_bytes_per_chunk / sb->s_blocksize);
> +
> +		buf->f_bfree =
> +		    yaffs_get_n_free_chunks(dev) *
> +		    (dev->data_bytes_per_chunk / sb->s_blocksize);
> +	}
> +
> +	buf->f_files = 0;
> +	buf->f_ffree = 0;
> +	buf->f_bavail = buf->f_bfree;
> +
> +	yaffs_gross_unlock(dev);
> +	return 0;
> +}
> +
> +static void yaffs_flush_inodes(struct super_block *sb)
> +{
> +	struct inode *iptr;
> +	struct yaffs_obj *obj;
> +
> +	list_for_each_entry(iptr, &sb->s_inodes, i_sb_list) {
> +		obj = yaffs_inode_to_obj(iptr);
> +		if (obj) {
> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"flushing obj %d", obj->obj_id);
> +			yaffs_flush_file(obj, 1, 0);
> +		}
> +	}
> +}
> +
> +static void yaffs_flush_super(struct super_block *sb, int do_checkpoint)
> +{
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +
> +	if (!dev)
> +		return;
> +
> +	yaffs_flush_inodes(sb);
> +	yaffs_update_dirty_dirs(dev);
> +	yaffs_flush_whole_cache(dev);
> +	if (do_checkpoint)
> +		yaffs_checkpoint_save(dev);
> +}
> +
> +static unsigned yaffs_bg_gc_urgency(struct yaffs_dev *dev)
> +{
> +	unsigned erased_chunks =
> +	    dev->n_erased_blocks * dev->param.chunks_per_block;
> +	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
> +	unsigned scattered = 0;	/* Free chunks not in an erased block */
> +
> +	if (erased_chunks < dev->n_free_chunks)
> +		scattered = (dev->n_free_chunks - erased_chunks);
> +
> +	if (!context->bg_running)
> +		return 0;
> +	else if (scattered < (dev->param.chunks_per_block * 2))
> +		return 0;
> +	else if (erased_chunks > dev->n_free_chunks / 2)
> +		return 0;
> +	else if (erased_chunks > dev->n_free_chunks / 4)
> +		return 1;
> +	else
> +		return 2;
> +}
> +
> +static int yaffs_do_sync_fs(struct super_block *sb, int request_checkpoint)
> +{
> +
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +	unsigned int oneshot_checkpoint = (yaffs_auto_checkpoint & 4);
> +	unsigned gc_urgent = yaffs_bg_gc_urgency(dev);
> +	int do_checkpoint;
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
> +		"yaffs_do_sync_fs: gc-urgency %d %s %s%s",
> +		gc_urgent,
> +		sb->s_dirt ? "dirty" : "clean",
> +		request_checkpoint ? "checkpoint requested" : "no checkpoint",
> +		oneshot_checkpoint ? " one-shot" : "");
> +
> +	yaffs_gross_lock(dev);
> +	do_checkpoint = ((request_checkpoint && !gc_urgent) ||
> +			 oneshot_checkpoint) && !dev->is_checkpointed;
> +
> +	if (sb->s_dirt || do_checkpoint) {
> +		yaffs_flush_super(sb, !dev->is_checkpointed && do_checkpoint);
> +		sb->s_dirt = 0;
> +		if (oneshot_checkpoint)
> +			yaffs_auto_checkpoint &= ~4;
> +	}
> +	yaffs_gross_unlock(dev);
> +
> +	return 0;
> +}
> +
> +/*
> + * yaffs background thread functions .
> + * yaffs_bg_thread_fn() the thread function
> + * yaffs_bg_start() launches the background thread.
> + * yaffs_bg_stop() cleans up the background thread.
> + *
> + * NB:
> + * The thread should only run after the yaffs is initialised
> + * The thread should be stopped before yaffs is unmounted.
> + * The thread should not do any writing while the fs is in read only.
> + */
> +
> +void yaffs_background_waker(unsigned long data)
> +{
> +	wake_up_process((struct task_struct *)data);
> +}
> +
> +static int yaffs_bg_thread_fn(void *data)
> +{
> +	struct yaffs_dev *dev = (struct yaffs_dev *)data;
> +	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
> +	unsigned long now = jiffies;
> +	unsigned long next_dir_update = now;
> +	unsigned long next_gc = now;
> +	unsigned long expires;
> +	unsigned int urgency;
> +	int gc_result;
> +	struct timer_list timer;
> +
> +	yaffs_trace(YAFFS_TRACE_BACKGROUND,
> +		"yaffs_background starting for dev %p", (void *)dev);
> +
> +	set_freezable();
> +	while (context->bg_running) {
> +		yaffs_trace(YAFFS_TRACE_BACKGROUND, "yaffs_background");
> +
> +		if (kthread_should_stop())
> +			break;
> +
> +		if (try_to_freeze())
> +			continue;
> +
> +		yaffs_gross_lock(dev);
> +
> +		now = jiffies;
> +
> +		if (time_after(now, next_dir_update) && yaffs_bg_enable) {
> +			yaffs_update_dirty_dirs(dev);
> +			next_dir_update = now + HZ;
> +		}
> +
> +		if (time_after(now, next_gc) && yaffs_bg_enable) {
> +			if (!dev->is_checkpointed) {
> +				urgency = yaffs_bg_gc_urgency(dev);
> +				gc_result = yaffs_bg_gc(dev, urgency);
> +				if (urgency > 1)
> +					next_gc = now + HZ / 20 + 1;

The msecs_to_jiffies macro could make the times here clearer.

> +				else if (urgency > 0)
> +					next_gc = now + HZ / 10 + 1;
> +				else
> +					next_gc = now + HZ * 2;
> +			} else	{
> +				/*
> +				 * gc not running so set to next_dir_update
> +				 * to cut down on wake ups
> +				 */
> +				next_gc = next_dir_update;
> +			}
> +		}
> +		yaffs_gross_unlock(dev);
> +		expires = next_dir_update;
> +		if (time_before(next_gc, expires))
> +			expires = next_gc;
> +		if (time_before(expires, now))
> +			expires = now + HZ;
> +
> +		init_timer_on_stack(&timer);
> +		timer.expires = expires + 1;
> +		timer.data = (unsigned long)current;
> +		timer.function = yaffs_background_waker;
> +
> +		set_current_state(TASK_INTERRUPTIBLE);
> +		add_timer(&timer);
> +		schedule();
> +		del_timer_sync(&timer);
> +	}
> +
> +	return 0;
> +}
> +
> +static int yaffs_bg_start(struct yaffs_dev *dev)
> +{
> +	int retval = 0;
> +	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
> +
> +	if (dev->read_only)
> +		return -1;

Proper errno value.

> +
> +	context->bg_running = 1;
> +
> +	context->bg_thread = kthread_run(yaffs_bg_thread_fn,
> +					 (void *)dev, "yaffs-bg-%d",
> +					 context->mount_id);
> +
> +	if (IS_ERR(context->bg_thread)) {
> +		retval = PTR_ERR(context->bg_thread);
> +		context->bg_thread = NULL;
> +		context->bg_running = 0;
> +	}
> +	return retval;
> +}
> +
> +static void yaffs_bg_stop(struct yaffs_dev *dev)
> +{
> +	struct yaffs_linux_context *ctxt = yaffs_dev_to_lc(dev);
> +
> +	ctxt->bg_running = 0;
> +
> +	if (ctxt->bg_thread) {
> +		kthread_stop(ctxt->bg_thread);
> +		ctxt->bg_thread = NULL;
> +	}
> +}
> +
> +static void yaffs_write_super(struct super_block *sb)
> +{
> +	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 2);
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
> +		"yaffs_write_super%s",
> +		request_checkpoint ? " checkpt" : "");
> +
> +	yaffs_do_sync_fs(sb, request_checkpoint);
> +
> +}
> +
> +static int yaffs_sync_fs(struct super_block *sb, int wait)
> +{
> +	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 1);
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC,
> +		"yaffs_sync_fs%s", request_checkpoint ? " checkpt" : "");
> +
> +	yaffs_do_sync_fs(sb, request_checkpoint);
> +
> +	return 0;
> +}
> +
> +static LIST_HEAD(yaffs_context_list);
> +struct mutex yaffs_context_lock;

Should be static?

> +struct yaffs_options {
> +	int inband_tags;
> +	int skip_checkpoint_read;
> +	int skip_checkpoint_write;
> +	int no_cache;
> +	int tags_ecc_on;
> +	int tags_ecc_overridden;
> +	int lazy_loading_enabled;
> +	int lazy_loading_overridden;
> +	int empty_lost_and_found;
> +	int empty_lost_and_found_overridden;
> +};

Also should be static?

> +
> +#define MAX_OPT_LEN 30
> +static int yaffs_parse_options(struct yaffs_options *options,
> +				const char *options_str)
> +{
> +	char cur_opt[MAX_OPT_LEN + 1];
> +	int p;
> +	int error = 0;
> +
> +	/* Parse through the options which is a comma seperated list */
> +
> +	while (options_str && *options_str && !error) {
> +		memset(cur_opt, 0, MAX_OPT_LEN + 1);
> +		p = 0;
> +
> +		while (*options_str == ',')
> +			options_str++;
> +
> +		while (*options_str && *options_str != ',') {
> +			if (p < MAX_OPT_LEN) {
> +				cur_opt[p] = *options_str;
> +				p++;
> +			}
> +			options_str++;
> +		}
> +
> +		if (!strcmp(cur_opt, "inband-tags")) {
> +			options->inband_tags = 1;
> +		} else if (!strcmp(cur_opt, "tags-ecc-off")) {
> +			options->tags_ecc_on = 0;
> +			options->tags_ecc_overridden = 1;
> +		} else if (!strcmp(cur_opt, "tags-ecc-on")) {
> +			options->tags_ecc_on = 1;
> +			options->tags_ecc_overridden = 1;
> +		} else if (!strcmp(cur_opt, "lazy-loading-off")) {
> +			options->lazy_loading_enabled = 0;
> +			options->lazy_loading_overridden = 1;
> +		} else if (!strcmp(cur_opt, "lazy-loading-on")) {
> +			options->lazy_loading_enabled = 1;
> +			options->lazy_loading_overridden = 1;
> +		} else if (!strcmp(cur_opt, "empty-lost-and-found-off")) {
> +			options->empty_lost_and_found = 0;
> +			options->empty_lost_and_found_overridden = 1;
> +		} else if (!strcmp(cur_opt, "empty-lost-and-found-on")) {
> +			options->empty_lost_and_found = 1;
> +			options->empty_lost_and_found_overridden = 1;
> +		} else if (!strcmp(cur_opt, "no-cache")) {
> +			options->no_cache = 1;
> +		} else if (!strcmp(cur_opt, "no-checkpoint-read")) {
> +			options->skip_checkpoint_read = 1;
> +		} else if (!strcmp(cur_opt, "no-checkpoint-write")) {
> +			options->skip_checkpoint_write = 1;
> +		} else if (!strcmp(cur_opt, "no-checkpoint")) {
> +			options->skip_checkpoint_read = 1;
> +			options->skip_checkpoint_write = 1;
> +		} else {
> +			printk(KERN_INFO "yaffs: Bad mount option \"%s\"\n",
> +			       cur_opt);

Probably should be KERN_ERR or KERN_WARN

> +			error = 1;
> +		}
> +	}
> +	return error;
> +}
> +
> +static const struct address_space_operations yaffs_file_address_operations = {
> +	.readpage = yaffs_readpage,
> +	.writepage = yaffs_writepage,
> +	.write_begin = yaffs_write_begin,
> +	.write_end = yaffs_write_end,
> +};
> +
> +
> +
> +static const struct inode_operations yaffs_file_inode_operations = {
> +	.setattr = yaffs_setattr,
> +#ifdef CONFIG_YAFFS_XATTR
> +	.setxattr = yaffs_setxattr,
> +	.getxattr = yaffs_getxattr,
> +	.listxattr = yaffs_listxattr,
> +	.removexattr = yaffs_removexattr,
> +#endif
> +};
> +
> +static const struct inode_operations yaffs_symlink_inode_operations = {
> +	.readlink = yaffs_readlink,
> +	.follow_link = yaffs_follow_link,
> +	.put_link = yaffs_put_link,
> +	.setattr = yaffs_setattr,
> +#ifdef CONFIG_YAFFS_XATTR
> +	.setxattr = yaffs_setxattr,
> +	.getxattr = yaffs_getxattr,
> +	.listxattr = yaffs_listxattr,
> +	.removexattr = yaffs_removexattr,
> +#endif
> +};
> +
> +static void yaffs_fill_inode_from_obj(struct inode *inode,
> +				      struct yaffs_obj *obj)
> +{
> +	if (inode && obj) {
> +		/* Check mode against the variant type
> +		 * and attempt to repair if broken. */
> +		u32 mode = obj->yst_mode;
> +		switch (obj->variant_type) {
> +		case YAFFS_OBJECT_TYPE_FILE:
> +			if (!S_ISREG(mode)) {
> +				obj->yst_mode &= ~S_IFMT;
> +				obj->yst_mode |= S_IFREG;
> +			}
> +
> +			break;
> +		case YAFFS_OBJECT_TYPE_SYMLINK:
> +			if (!S_ISLNK(mode)) {
> +				obj->yst_mode &= ~S_IFMT;
> +				obj->yst_mode |= S_IFLNK;
> +			}
> +
> +			break;
> +		case YAFFS_OBJECT_TYPE_DIRECTORY:
> +			if (!S_ISDIR(mode)) {
> +				obj->yst_mode &= ~S_IFMT;
> +				obj->yst_mode |= S_IFDIR;
> +			}
> +
> +			break;
> +		case YAFFS_OBJECT_TYPE_UNKNOWN:
> +		case YAFFS_OBJECT_TYPE_HARDLINK:
> +		case YAFFS_OBJECT_TYPE_SPECIAL:
> +		default:
> +			/* TODO? */
> +			break;
> +		}
> +
> +		inode->i_flags |= S_NOATIME;
> +
> +		inode->i_ino = obj->obj_id;
> +		inode->i_mode = obj->yst_mode;
> +		inode->i_uid = obj->yst_uid;
> +		inode->i_gid = obj->yst_gid;
> +
> +		inode->i_rdev = old_decode_dev(obj->yst_rdev);
> +
> +		inode->i_atime.tv_sec = (time_t) (obj->yst_atime);

Why are yst_[amt]time not already time_t?

> +		inode->i_atime.tv_nsec = 0;
> +		inode->i_mtime.tv_sec = (time_t) obj->yst_mtime;
> +		inode->i_mtime.tv_nsec = 0;
> +		inode->i_ctime.tv_sec = (time_t) obj->yst_ctime;
> +		inode->i_ctime.tv_nsec = 0;
> +		inode->i_size = yaffs_get_obj_length(obj);
> +		inode->i_blocks = (inode->i_size + 511) >> 9;
> +
> +		inode->i_nlink = yaffs_get_obj_link_count(obj);
> +
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_fill_inode mode %x uid %d gid %d size %d count %d",
> +			inode->i_mode, inode->i_uid, inode->i_gid,
> +			(int)inode->i_size, atomic_read(&inode->i_count));
> +
> +		switch (obj->yst_mode & S_IFMT) {
> +		default:	/* fifo, device or socket */
> +			init_special_inode(inode, obj->yst_mode,
> +					   old_decode_dev(obj->yst_rdev));
> +			break;
> +		case S_IFREG:	/* file */
> +			inode->i_op = &yaffs_file_inode_operations;
> +			inode->i_fop = &yaffs_file_operations;
> +			inode->i_mapping->a_ops =
> +			    &yaffs_file_address_operations;
> +			break;
> +		case S_IFDIR:	/* directory */
> +			inode->i_op = &yaffs_dir_inode_operations;
> +			inode->i_fop = &yaffs_dir_operations;
> +			break;
> +		case S_IFLNK:	/* symlink */
> +			inode->i_op = &yaffs_symlink_inode_operations;
> +			break;
> +		}
> +
> +		yaffs_inode_to_obj_lv(inode) = obj;
> +		obj->my_inode = inode;
> +
> +	} else {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_fill_inode invalid parameters");
> +	}
> +}
> +
> +static void yaffs_put_super(struct super_block *sb)
> +{
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_put_super");
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
> +		"Shutting down yaffs background thread");
> +	yaffs_bg_stop(dev);
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
> +		"yaffs background thread shut down");
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_flush_super(sb, 1);
> +
> +	if (yaffs_dev_to_lc(dev)->put_super_fn)
> +		yaffs_dev_to_lc(dev)->put_super_fn(sb);
> +
> +	yaffs_deinitialise(dev);
> +
> +	yaffs_gross_unlock(dev);
> +	mutex_lock(&yaffs_context_lock);
> +	list_del_init(&(yaffs_dev_to_lc(dev)->context_list));
> +	mutex_unlock(&yaffs_context_lock);
> +
> +	if (yaffs_dev_to_lc(dev)->spare_buffer) {
> +		kfree(yaffs_dev_to_lc(dev)->spare_buffer);
> +		yaffs_dev_to_lc(dev)->spare_buffer = NULL;
> +	}
> +
> +	kfree(dev);
> +}
> +
> +static void yaffs_mtd_put_super(struct super_block *sb)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(yaffs_super_to_dev(sb));
> +
> +	if (mtd->sync)
> +		mtd->sync(mtd);
> +
> +	put_mtd_device(mtd);
> +}
> +
> +static const struct super_operations yaffs_super_ops = {
> +	.statfs = yaffs_statfs,
> +	.put_super = yaffs_put_super,
> +	.evict_inode = yaffs_evict_inode,
> +	.sync_fs = yaffs_sync_fs,
> +	.write_super = yaffs_write_super,

Nitpick: tab-delimt struct initialisers to make them more readable.

> +};
> +
> +static struct super_block *yaffs_internal_read_super(int yaffs_version,
> +						     struct super_block *sb,
> +						     void *data, int silent)
> +{
> +	int n_blocks;
> +	struct inode *inode = NULL;
> +	struct dentry *root;
> +	struct yaffs_dev *dev = 0;
> +	char devname_buf[BDEVNAME_SIZE + 1];
> +	struct mtd_info *mtd;
> +	int err;
> +	char *data_str = (char *)data;

Shouldn't need the cast.

> +	struct yaffs_linux_context *context = NULL;
> +	struct yaffs_param *param;
> +	int read_only = 0;
> +	struct yaffs_options options;
> +	unsigned mount_id;
> +	int found;
> +	struct yaffs_linux_context *context_iterator;
> +	struct list_head *l;
> +
> +	if (!sb) {
> +		printk(KERN_INFO "yaffs: sb is NULL\n");

KERN_ERR/KERN_WARN?

> +		return NULL;
> +	}
> +
> +	sb->s_magic = YAFFS_MAGIC;
> +	sb->s_op = &yaffs_super_ops;
> +	sb->s_flags |= MS_NOATIME;
> +
> +	read_only = ((sb->s_flags & MS_RDONLY) != 0);
> +
> +	sb->s_export_op = &yaffs_export_ops;
> +
> +	if (!sb->s_dev)
> +		printk(KERN_INFO "yaffs: sb->s_dev is NULL\n");
> +	else if (!yaffs_devname(sb, devname_buf))
> +		printk(KERN_INFO "yaffs: devname is NULL\n");
> +	else
> +		printk(KERN_INFO "yaffs: dev is %d name is \"%s\" %s\n",
> +		       sb->s_dev,
> +		       yaffs_devname(sb, devname_buf), read_only ? "ro" : "rw");
> +
> +	if (!data_str)
> +		data_str = "";
> +
> +	printk(KERN_INFO "yaffs: passed flags \"%s\"\n", data_str);
> +
> +	memset(&options, 0, sizeof(options));
> +
> +	if (yaffs_parse_options(&options, data_str)) {
> +		/* Option parsing failed */
> +		return NULL;
> +	}
> +
> +	sb->s_blocksize = PAGE_CACHE_SIZE;
> +	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_read_super: Using yaffs%d", yaffs_version);
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_read_super: block size %d", (int)(sb->s_blocksize));
> +
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"Attempting MTD mount of %u.%u,\"%s\"",
> +		MAJOR(sb->s_dev), MINOR(sb->s_dev),
> +		yaffs_devname(sb, devname_buf));
> +
> +	/* Check it's an mtd device..... */
> +	if (MAJOR(sb->s_dev) != MTD_BLOCK_MAJOR)
> +		return NULL;	/* This isn't an mtd device */
> +
> +	/* Get the device */
> +	mtd = get_mtd_device(NULL, MINOR(sb->s_dev));
> +	if (!mtd) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"MTD device #%u doesn't appear to exist",
> +			MINOR(sb->s_dev));
> +		return NULL;
> +	}
> +	/* Check it's NAND */
> +	if (mtd->type != MTD_NANDFLASH) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"MTD device is not NAND it's type %d",
> +			mtd->type);
> +		return NULL;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS, " erase %p", mtd->erase);
> +	yaffs_trace(YAFFS_TRACE_OS, " read %p", mtd->read);
> +	yaffs_trace(YAFFS_TRACE_OS, " write %p", mtd->write);
> +	yaffs_trace(YAFFS_TRACE_OS, " readoob %p", mtd->read_oob);
> +	yaffs_trace(YAFFS_TRACE_OS, " writeoob %p", mtd->write_oob);
> +	yaffs_trace(YAFFS_TRACE_OS, " block_isbad %p", mtd->block_isbad);
> +	yaffs_trace(YAFFS_TRACE_OS, " block_markbad %p", mtd->block_markbad);
> +	yaffs_trace(YAFFS_TRACE_OS, " writesize %d", mtd->writesize);
> +	yaffs_trace(YAFFS_TRACE_OS, " oobsize %d", mtd->oobsize);
> +	yaffs_trace(YAFFS_TRACE_OS, " erasesize %d", mtd->erasesize);
> +	yaffs_trace(YAFFS_TRACE_OS, " size %lld", mtd->size);
> +
> +#ifdef CONFIG_YAFFS_AUTO_YAFFS2

should also depend on CONFIG_YAFFS_YAFFS2 I guess?

> +
> +	if (yaffs_version == 1 && mtd->writesize >= 2048) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs2");
> +		yaffs_version = 2;
> +	}
> +
> +	/* Added NCB 26/5/2006 for completeness */
> +	if (yaffs_version == 2 && !options.inband_tags &&
> +		mtd->writesize == 512) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs1");
> +		yaffs_version = 1;
> +	}
> +#endif
> +
> +	if (yaffs_version == 2) {
> +		/* Check for version 2 style functions */
> +		if (!mtd->erase ||
> +		    !mtd->block_isbad ||
> +		    !mtd->block_markbad ||
> +		    !mtd->read ||
> +		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not support required functions");
> +			return NULL;
> +		}
> +
> +		if ((mtd->writesize < YAFFS_MIN_YAFFS2_CHUNK_SIZE ||
> +		     mtd->oobsize < YAFFS_MIN_YAFFS2_SPARE_SIZE) &&
> +		    !options.inband_tags) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not have the right page sizes");
> +			return NULL;
> +		}
> +	} else {
> +		/* Check for V1 style functions */
> +		if (!mtd->erase ||
> +		    !mtd->read ||
> +		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not support required functions");
> +			return NULL;
> +		}
> +
> +		if (mtd->writesize < YAFFS_BYTES_PER_CHUNK ||
> +		    mtd->oobsize != YAFFS_BYTES_PER_SPARE) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not support have the right page sizes");
> +			return NULL;
> +		}
> +	}
> +
> +	/* OK, so if we got here, we have an MTD that's NAND and looks
> +	 * like it has the right capabilities
> +	 * Set the struct yaffs_dev up for mtd
> +	 */
> +
> +	if (!read_only && !(mtd->flags & MTD_WRITEABLE)) {
> +		read_only = 1;
> +		printk(KERN_INFO
> +		       "yaffs: mtd is read only, setting superblock read only");
> +		sb->s_flags |= MS_RDONLY;
> +	}
> +
> +	dev = kmalloc(sizeof(struct yaffs_dev), GFP_KERNEL);
> +	context = kmalloc(sizeof(struct yaffs_linux_context), GFP_KERNEL);
> +
> +	if (!dev || !context) {
> +		kfree(dev);
> +		kfree(context);
> +		dev = NULL;
> +		context = NULL;

It looks like you should just bail here. You have an explicit check for
!dev below, but if you manage to allocate dev, but not context you will
blow up on the memset below. So you just want something like:

	if (!dev || !context) {
		kfree(dev);
		kfree(context);
		return NULL;
	}

> +	}
> +
> +	if (!dev) {
> +		/* Deep shit could not allocate device structure */
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"yaffs_read_super failed trying to allocate yaffs_dev");
> +		return NULL;
> +	}
> +	memset(dev, 0, sizeof(struct yaffs_dev));
> +	param = &(dev->param);
> +
> +	memset(context, 0, sizeof(struct yaffs_linux_context));
> +	dev->os_context = context;
> +	INIT_LIST_HEAD(&(context->context_list));
> +	context->dev = dev;
> +	context->super = sb;
> +
> +	dev->read_only = read_only;
> +
> +	sb->s_fs_info = dev;
> +
> +	dev->driver_context = mtd;
> +	param->name = mtd->name;
> +
> +	/* Set up the memory size parameters.... */
> +
> +	n_blocks =
> +	    YCALCBLOCKS(mtd->size,
> +			(YAFFS_CHUNKS_PER_BLOCK * YAFFS_BYTES_PER_CHUNK));
> +
> +	param->start_block = 0;
> +	param->end_block = n_blocks - 1;
> +	param->chunks_per_block = YAFFS_CHUNKS_PER_BLOCK;
> +	param->total_bytes_per_chunk = YAFFS_BYTES_PER_CHUNK;
> +	param->n_reserved_blocks = 5;
> +	param->n_caches = (options.no_cache) ? 0 : 10;
> +	param->inband_tags = options.inband_tags;
> +
> +#ifdef CONFIG_YAFFS_DISABLE_LAZY_LOAD
> +	param->disable_lazy_load = 1;
> +#endif
> +#ifdef CONFIG_YAFFS_XATTR
> +	param->enable_xattr = 1;
> +#endif

If these parameters are bool, I think you can somehow do:

param->enable_xattr = CONFIG_YAFFS_XATTR;

Though I still think some of these ifdefs need to be converted to
runtime options :-).	

> +	if (options.lazy_loading_overridden)
> +		param->disable_lazy_load = !options.lazy_loading_enabled;
> +
> +#ifdef CONFIG_YAFFS_DISABLE_TAGS_ECC
> +	param->no_tags_ecc = 1;
> +#endif
> +
> +#ifdef CONFIG_YAFFS_DISABLE_BACKGROUND
> +#else
> +	param->defered_dir_update = 1;
> +#endif
> +
> +	if (options.tags_ecc_overridden)
> +		param->no_tags_ecc = !options.tags_ecc_on;
> +
> +#ifdef CONFIG_YAFFS_EMPTY_LOST_AND_FOUND
> +	param->empty_lost_n_found = 1;
> +#endif
> +
> +#ifdef CONFIG_YAFFS_DISABLE_BLOCK_REFRESHING
> +	param->refresh_period = 0;
> +#else
> +	param->refresh_period = 500;
> +#endif
> +
> +#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
> +	param->always_check_erased = 1;
> +#endif
> +
> +	if (options.empty_lost_and_found_overridden)
> +		param->empty_lost_n_found = options.empty_lost_and_found;
> +
> +	/* ... and the functions. */
> +	if (yaffs_version == 2) {
> +		param->write_chunk_tags_fn = nandmtd2_write_chunk_tags;
> +		param->read_chunk_tags_fn = nandmtd2_read_chunk_tags;
> +		param->bad_block_fn = nandmtd2_mark_block_bad;
> +		param->query_block_fn = nandmtd2_query_block;
> +		yaffs_dev_to_lc(dev)->spare_buffer =
> +				kmalloc(mtd->oobsize, GFP_NOFS);
> +		param->is_yaffs2 = 1;
> +		param->total_bytes_per_chunk = mtd->writesize;
> +		param->chunks_per_block = mtd->erasesize / mtd->writesize;
> +		n_blocks = YCALCBLOCKS(mtd->size, mtd->erasesize);
> +
> +		param->start_block = 0;
> +		param->end_block = n_blocks - 1;
> +	} else {
> +		/* use the MTD interface in yaffs_mtdif1.c */
> +		param->write_chunk_tags_fn = nandmtd1_write_chunk_tags;
> +		param->read_chunk_tags_fn = nandmtd1_read_chunk_tags;
> +		param->bad_block_fn = nandmtd1_mark_block_bad;
> +		param->query_block_fn = nandmtd1_query_block;
> +		param->is_yaffs2 = 0;
> +	}
> +	/* ... and common functions */
> +	param->erase_fn = nandmtd_erase_block;
> +	param->initialise_flash_fn = nandmtd_initialise;
> +
> +	yaffs_dev_to_lc(dev)->put_super_fn = yaffs_mtd_put_super;
> +
> +	param->sb_dirty_fn = yaffs_touch_super;
> +	param->gc_control = yaffs_gc_control_callback;
> +
> +	yaffs_dev_to_lc(dev)->super = sb;
> +
> +#ifndef CONFIG_YAFFS_DOES_ECC
> +	param->use_nand_ecc = 1;
> +#endif
> +
> +	param->skip_checkpt_rd = options.skip_checkpoint_read;
> +	param->skip_checkpt_wr = options.skip_checkpoint_write;
> +
> +	mutex_lock(&yaffs_context_lock);
> +	/* Get a mount id */
> +	found = 0;
> +	for (mount_id = 0; !found; mount_id++) {
> +		found = 1;
> +		list_for_each(l, &yaffs_context_list) {
> +			context_iterator =
> +				list_entry(l, struct yaffs_linux_context,
> +					context_list);

	list_for_each_entry(context_iterator, &yaffs_context_list,
		context_list)

> +			if (context_iterator->mount_id == mount_id)
> +				found = 0;
> +		}
> +	}
> +	context->mount_id = mount_id;
> +
> +	list_add_tail(&(yaffs_dev_to_lc(dev)->context_list),
> +		      &yaffs_context_list);
> +	mutex_unlock(&yaffs_context_lock);
> +
> +	/* Directory search handling... */
> +	INIT_LIST_HEAD(&(yaffs_dev_to_lc(dev)->search_contexts));
> +	param->remove_obj_fn = yaffs_remove_obj_callback;
> +
> +	mutex_init(&(yaffs_dev_to_lc(dev)->gross_lock));
> +
> +	yaffs_gross_lock(dev);
> +
> +	err = yaffs_guts_initialise(dev);

We seem to carry on for a while if this function fails?

> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_read_super: guts initialised %s",
> +		(err == YAFFS_OK) ? "OK" : "FAILED");
> +
> +	if (err == YAFFS_OK)
> +		yaffs_bg_start(dev);
> +
> +	if (!context->bg_thread)
> +		param->defered_dir_update = 0;
> +
> +	/* Release lock before yaffs_get_inode() */
> +	yaffs_gross_unlock(dev);
> +
> +	/* Create root inode */
> +	if (err == YAFFS_OK)
> +		inode = yaffs_get_inode(sb, S_IFDIR | 0755, 0, yaffs_root(dev));
> +
> +	if (!inode)
> +		return NULL;
> +
> +	inode->i_op = &yaffs_dir_inode_operations;
> +	inode->i_fop = &yaffs_dir_operations;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: got root inode");
> +
> +	root = d_alloc_root(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: d_alloc_root done");
> +
> +	if (!root) {
> +		iput(inode);
> +		return NULL;
> +	}
> +	sb->s_root = root;
> +	sb->s_dirt = !dev->is_checkpointed;
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"yaffs_read_super: is_checkpointed %d",
> +		dev->is_checkpointed);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: done");
> +	return sb;
> +}
> +
> +static int yaffs_internal_read_super_mtd(struct super_block *sb, void *data,
> +					 int silent)
> +{
> +	return yaffs_internal_read_super(1, sb, data, silent) ? 0 : -EINVAL;
> +}
> +
> +static int yaffs_read_super(struct file_system_type *fs,
> +			    int flags, const char *dev_name,
> +			    void *data, struct vfsmount *mnt)
> +{
> +
> +	return get_sb_bdev(fs, flags, dev_name, data,
> +			   yaffs_internal_read_super_mtd, mnt);
> +}
> +
> +static struct file_system_type yaffs_fs_type = {
> +	.owner = THIS_MODULE,
> +	.name = "yaffs",
> +	.get_sb = yaffs_read_super,
> +	.kill_sb = kill_block_super,
> +	.fs_flags = FS_REQUIRES_DEV,
> +};
> +
> +#ifdef CONFIG_YAFFS_YAFFS2
> +
> +static int yaffs2_internal_read_super_mtd(struct super_block *sb, void *data,
> +					  int silent)
> +{
> +	return yaffs_internal_read_super(2, sb, data, silent) ? 0 : -EINVAL;
> +}
> +
> +static int yaffs2_read_super(struct file_system_type *fs,
> +			     int flags, const char *dev_name, void *data,
> +			     struct vfsmount *mnt)
> +{
> +	return get_sb_bdev(fs, flags, dev_name, data,
> +			   yaffs2_internal_read_super_mtd, mnt);
> +}
> +
> +static struct file_system_type yaffs2_fs_type = {
> +	.owner = THIS_MODULE,
> +	.name = "yaffs2",
> +	.get_sb = yaffs2_read_super,
> +	.kill_sb = kill_block_super,
> +	.fs_flags = FS_REQUIRES_DEV,
> +};
> +#endif /* CONFIG_YAFFS_YAFFS2 */
> +
> +static struct proc_dir_entry *my_proc_entry;
> +
> +static char *yaffs_dump_dev_part0(char *buf, struct yaffs_dev *dev)
> +{
> +	struct yaffs_param *param = &dev->param;
> +
> +	buf += sprintf(buf, "start_block........... %d\n", param->start_block);
> +	buf += sprintf(buf, "end_block............. %d\n", param->end_block);
> +	buf += sprintf(buf, "total_bytes_per_chunk. %d\n",
> +			param->total_bytes_per_chunk);
> +	buf += sprintf(buf, "use_nand_ecc.......... %d\n",
> +			param->use_nand_ecc);
> +	buf += sprintf(buf, "no_tags_ecc........... %d\n", param->no_tags_ecc);
> +	buf += sprintf(buf, "is_yaffs2............. %d\n", param->is_yaffs2);
> +	buf += sprintf(buf, "inband_tags........... %d\n", param->inband_tags);
> +	buf += sprintf(buf, "empty_lost_n_found.... %d\n",
> +			param->empty_lost_n_found);
> +	buf += sprintf(buf, "disable_lazy_load..... %d\n",
> +			param->disable_lazy_load);
> +	buf += sprintf(buf, "refresh_period........ %d\n",
> +			param->refresh_period);
> +	buf += sprintf(buf, "n_caches.............. %d\n", param->n_caches);
> +	buf += sprintf(buf, "n_reserved_blocks..... %d\n",
> +			param->n_reserved_blocks);
> +	buf += sprintf(buf, "always_check_erased... %d\n",
> +			param->always_check_erased);

How big is buf? snprintf with maxlen would be better.

> +
> +	return buf;
> +}
> +
> +static char *yaffs_dump_dev_part1(char *buf, struct yaffs_dev *dev)
> +{
> +	buf +=
> +	    sprintf(buf, "data_bytes_per_chunk.. %d\n",
> +		    dev->data_bytes_per_chunk);
> +	buf += sprintf(buf, "chunk_grp_bits........ %d\n", dev->chunk_grp_bits);
> +	buf += sprintf(buf, "chunk_grp_size........ %d\n", dev->chunk_grp_size);
> +	buf +=
> +	    sprintf(buf, "n_erased_blocks....... %d\n", dev->n_erased_blocks);
> +	buf +=
> +	    sprintf(buf, "blocks_in_checkpt..... %d\n", dev->blocks_in_checkpt);
> +	buf += sprintf(buf, "\n");
> +	buf += sprintf(buf, "n_tnodes.............. %d\n", dev->n_tnodes);
> +	buf += sprintf(buf, "n_obj................. %d\n", dev->n_obj);
> +	buf += sprintf(buf, "n_free_chunks......... %d\n", dev->n_free_chunks);
> +	buf += sprintf(buf, "\n");
> +	buf += sprintf(buf, "n_page_writes......... %u\n", dev->n_page_writes);
> +	buf += sprintf(buf, "n_page_reads.......... %u\n", dev->n_page_reads);
> +	buf += sprintf(buf, "n_erasures............ %u\n", dev->n_erasures);
> +	buf += sprintf(buf, "n_gc_copies........... %u\n", dev->n_gc_copies);
> +	buf += sprintf(buf, "all_gcs............... %u\n", dev->all_gcs);
> +	buf +=
> +	    sprintf(buf, "passive_gc_count...... %u\n", dev->passive_gc_count);
> +	buf +=
> +	    sprintf(buf, "oldest_dirty_gc_count. %u\n",
> +		    dev->oldest_dirty_gc_count);
> +	buf += sprintf(buf, "n_gc_blocks........... %u\n", dev->n_gc_blocks);
> +	buf += sprintf(buf, "bg_gcs................ %u\n", dev->bg_gcs);
> +	buf +=
> +	    sprintf(buf, "n_retired_writes...... %u\n", dev->n_retired_writes);
> +	buf +=
> +	    sprintf(buf, "n_retired_blocks...... %u\n", dev->n_retired_blocks);
> +	buf += sprintf(buf, "n_ecc_fixed........... %u\n", dev->n_ecc_fixed);
> +	buf += sprintf(buf, "n_ecc_unfixed......... %u\n", dev->n_ecc_unfixed);
> +	buf +=
> +	    sprintf(buf, "n_tags_ecc_fixed...... %u\n", dev->n_tags_ecc_fixed);
> +	buf +=
> +	    sprintf(buf, "n_tags_ecc_unfixed.... %u\n",
> +		    dev->n_tags_ecc_unfixed);
> +	buf += sprintf(buf, "cache_hits............ %u\n", dev->cache_hits);
> +	buf +=
> +	    sprintf(buf, "n_deleted_files....... %u\n", dev->n_deleted_files);
> +	buf +=
> +	    sprintf(buf, "n_unlinked_files...... %u\n", dev->n_unlinked_files);
> +	buf += sprintf(buf, "refresh_count......... %u\n", dev->refresh_count);
> +	buf += sprintf(buf, "n_bg_deletions........ %u\n", dev->n_bg_deletions);
> +
> +	return buf;
> +}
> +
> +static int yaffs_proc_read(char *page,
> +			   char **start,
> +			   off_t offset, int count, int *eof, void *data)
> +{
> +	struct list_head *item;
> +	char *buf = page;
> +	int step = offset;
> +	int n = 0;
> +
> +	/* Get proc_file_read() to step 'offset' by one on each sucessive call.
> +	 * We use 'offset' (*ppos) to indicate where we are in dev_list.
> +	 * This also assumes the user has posted a read buffer large
> +	 * enough to hold the complete output; but that's life in /proc.
> +	 */
> +
> +	*(int *)start = 1;
> +
> +	/* Print header first */
> +	if (step == 0)
> +		buf += sprintf(buf, "YAFFS built:" __DATE__ " " __TIME__ "\n");
> +	else if (step == 1)
> +		buf += sprintf(buf, "\n");
> +	else {

IIRC you can use seq_file for this which is safer/easier than using sprintf.

> +		step -= 2;
> +
> +		mutex_lock(&yaffs_context_lock);
> +
> +		/* Locate and print the Nth entry.
> +		 * Order N-squared but N is small. */
> +		list_for_each(item, &yaffs_context_list) {
> +			struct yaffs_linux_context *dc =
> +			    list_entry(item, struct yaffs_linux_context,
> +				       context_list);
> +			struct yaffs_dev *dev = dc->dev;
> +
> +			if (n < (step & ~1)) {
> +				n += 2;
> +				continue;
> +			}
> +			if ((step & 1) == 0) {
> +				buf +=
> +				    sprintf(buf, "\nDevice %d \"%s\"\n", n,
> +					    dev->param.name);
> +				buf = yaffs_dump_dev_part0(buf, dev);
> +			} else {
> +				buf = yaffs_dump_dev_part1(buf, dev);
> +			}
> +
> +			break;
> +		}
> +		mutex_unlock(&yaffs_context_lock);
> +	}
> +
> +	return buf - page < count ? buf - page : count;
> +}
> +
> +
> +/**
> + * Set the verbosity of the warnings and error messages.
> + *
> + * Note that the names can only be a..z or _ with the current code.
> + */
> +
> +static struct {
> +	char *mask_name;
> +	unsigned mask_bitfield;
> +} mask_flags[] = {
> +	{"allocate", YAFFS_TRACE_ALLOCATE},
> +	{"always", YAFFS_TRACE_ALWAYS},
> +	{"background", YAFFS_TRACE_BACKGROUND},
> +	{"bad_blocks", YAFFS_TRACE_BAD_BLOCKS},
> +	{"buffers", YAFFS_TRACE_BUFFERS},
> +	{"bug", YAFFS_TRACE_BUG},
> +	{"checkpt", YAFFS_TRACE_CHECKPOINT},
> +	{"deletion", YAFFS_TRACE_DELETION},
> +	{"erase", YAFFS_TRACE_ERASE},
> +	{"error", YAFFS_TRACE_ERROR},
> +	{"gc_detail", YAFFS_TRACE_GC_DETAIL},
> +	{"gc", YAFFS_TRACE_GC},
> +	{"lock", YAFFS_TRACE_LOCK},
> +	{"mtd", YAFFS_TRACE_MTD},
> +	{"nandaccess", YAFFS_TRACE_NANDACCESS},
> +	{"os", YAFFS_TRACE_OS},
> +	{"scan_debug", YAFFS_TRACE_SCAN_DEBUG},
> +	{"scan", YAFFS_TRACE_SCAN},
> +	{"mount", YAFFS_TRACE_MOUNT},
> +	{"tracing", YAFFS_TRACE_TRACING},
> +	{"sync", YAFFS_TRACE_SYNC},
> +	{"write", YAFFS_TRACE_WRITE},
> +	{"verify", YAFFS_TRACE_VERIFY},
> +	{"verify_nand", YAFFS_TRACE_VERIFY_NAND},
> +	{"verify_full", YAFFS_TRACE_VERIFY_FULL},
> +	{"verify_all", YAFFS_TRACE_VERIFY_ALL},
> +	{"all", 0xffffffff},
> +	{"none", 0},
> +	{NULL, 0},
> +};
> +
> +#define MAX_MASK_NAME_LENGTH 40
> +static int yaffs_proc_write_trace_options(struct file *file, const char *buf,
> +					  unsigned long count, void *data)
> +{
> +	unsigned rg = 0, mask_bitfield;
> +	char *end;
> +	char *mask_name;
> +	const char *x;
> +	char substring[MAX_MASK_NAME_LENGTH + 1];
> +	int i;
> +	int done = 0;
> +	int add, len = 0;
> +	int pos = 0;

sysfs is probably a better interface for controlling this sort of thing.

> +	rg = yaffs_trace_mask;
> +
> +	while (!done && (pos < count)) {
> +		done = 1;
> +		while ((pos < count) && isspace(buf[pos]))
> +			pos++;
> +
> +		switch (buf[pos]) {
> +		case '+':
> +		case '-':
> +		case '=':
> +			add = buf[pos];
> +			pos++;
> +			break;
> +
> +		default:
> +			add = ' ';
> +			break;
> +		}
> +		mask_name = NULL;
> +
> +		mask_bitfield = simple_strtoul(buf + pos, &end, 0);
> +
> +		if (end > buf + pos) {
> +			mask_name = "numeral";
> +			len = end - (buf + pos);
> +			pos += len;
> +			done = 0;
> +		} else {
> +			for (x = buf + pos, i = 0;
> +			     (*x == '_' || (*x >= 'a' && *x <= 'z')) &&
> +			     i < MAX_MASK_NAME_LENGTH; x++, i++, pos++)
> +				substring[i] = *x;
> +			substring[i] = '\0';
> +
> +			for (i = 0; mask_flags[i].mask_name != NULL; i++) {
> +				if (strcmp(substring, mask_flags[i].mask_name)
> +				    == 0) {
> +					mask_name = mask_flags[i].mask_name;
> +					mask_bitfield =
> +					    mask_flags[i].mask_bitfield;
> +					done = 0;
> +					break;
> +				}
> +			}
> +		}
> +
> +		if (mask_name != NULL) {
> +			done = 0;
> +			switch (add) {
> +			case '-':
> +				rg &= ~mask_bitfield;
> +				break;
> +			case '+':
> +				rg |= mask_bitfield;
> +				break;
> +			case '=':
> +				rg = mask_bitfield;
> +				break;
> +			default:
> +				rg |= mask_bitfield;
> +				break;
> +			}
> +		}
> +	}
> +
> +	yaffs_trace_mask = rg | YAFFS_TRACE_ALWAYS;
> +
> +	printk(KERN_DEBUG "new trace = 0x%08X\n", yaffs_trace_mask);
> +
> +	if (rg & YAFFS_TRACE_ALWAYS) {
> +		for (i = 0; mask_flags[i].mask_name != NULL; i++) {
> +			char flag;
> +			flag = ((rg & mask_flags[i].mask_bitfield) ==
> +				mask_flags[i].mask_bitfield) ? '+' : '-';
> +			printk(KERN_DEBUG "%c%s\n", flag,
> +			       mask_flags[i].mask_name);
> +		}
> +	}
> +
> +	return count;
> +}
> +
> +static int yaffs_proc_write(struct file *file, const char *buf,
> +			    unsigned long count, void *data)
> +{
> +	return yaffs_proc_write_trace_options(file, buf, count, data);
> +}
> +
> +/* Stuff to handle installation of file systems */
> +struct file_system_to_install {
> +	struct file_system_type *fst;
> +	int installed;
> +};
> +
> +static struct file_system_to_install fs_to_install[] = {
> +	{&yaffs_fs_type, 0},
> +	{&yaffs2_fs_type, 0},
> +	{NULL, 0}
> +};
> +
> +static int __init init_yaffs_fs(void)
> +{
> +	int error = 0;
> +	struct file_system_to_install *fsinst;
> +
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"yaffs built " __DATE__ " " __TIME__ " Installing.");
> +
> +#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"\n\nYAFFS-WARNING CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED selected.\n\n\n");
> +#endif
> +
> +	mutex_init(&yaffs_context_lock);
> +
> +	/* Install the proc_fs entries */
> +	my_proc_entry = create_proc_entry("yaffs",
> +					  S_IRUGO | S_IFREG, NULL);
> +
> +	if (my_proc_entry) {
> +		my_proc_entry->write_proc = yaffs_proc_write;
> +		my_proc_entry->read_proc = yaffs_proc_read;
> +		my_proc_entry->data = NULL;
> +	} else {
> +		return -ENOMEM;
> +	}

Make the successful path the simple one:

	if (!my_proc_entry)
		return -ENOMEM;

> +
> +
> +	/* Now add the file system entries */
> +
> +	fsinst = fs_to_install;
> +
> +	while (fsinst->fst && !error) {
> +		error = register_filesystem(fsinst->fst);
> +		if (!error)
> +			fsinst->installed = 1;
> +		fsinst++;
> +	}
> +
> +	/* Any errors? uninstall  */
> +	if (error) {
> +		fsinst = fs_to_install;
> +
> +		while (fsinst->fst) {
> +			if (fsinst->installed) {
> +				unregister_filesystem(fsinst->fst);
> +				fsinst->installed = 0;
> +			}
> +			fsinst++;
> +		}
> +	}
> +
> +	return error;
> +}
> +
> +static void __exit exit_yaffs_fs(void)
> +{
> +
> +	struct file_system_to_install *fsinst;
> +
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"yaffs built " __DATE__ " " __TIME__ " removing.");
> +
> +	remove_proc_entry("yaffs", NULL);
> +
> +	fsinst = fs_to_install;
> +
> +	while (fsinst->fst) {
> +		if (fsinst->installed) {
> +			unregister_filesystem(fsinst->fst);
> +			fsinst->installed = 0;
> +		}
> +		fsinst++;
> +	}
> +}
> +
> +module_init(init_yaffs_fs)
> +module_exit(exit_yaffs_fs)
> +
> +MODULE_DESCRIPTION("YAFFS2 - a NAND specific flash file system");
> +MODULE_AUTHOR("Charles Manning, Aleph One Ltd., 2002-2010");
> +MODULE_LICENSE("GPL");
> diff --git a/fs/yaffs2/yportenv.h b/fs/yaffs2/yportenv.h
> new file mode 100644
> index 0000000..6cea9fe
> --- /dev/null
> +++ b/fs/yaffs2/yportenv.h
> @@ -0,0 +1,70 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2010 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YPORTENV_LINUX_H__
> +#define __YPORTENV_LINUX_H__
> +
> +#include <linux/version.h>
> +#include <linux/kernel.h>
> +#include <linux/mm.h>
> +#include <linux/sched.h>
> +#include <linux/string.h>
> +#include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +#include <linux/xattr.h>
> +#include <linux/list.h>
> +#include <linux/types.h>
> +#include <linux/fs.h>
> +#include <linux/stat.h>
> +#include <linux/sort.h>
> +#include <linux/bitops.h>

Are these all necessary? Each file should only include the headers it
actually requires. I don't image you need linux/version.h for mainline :-).

> +
> +#define YCHAR char
> +#define YUCHAR unsigned char
> +#define _Y(x)     x
> +
> +#define YAFFS_LOSTNFOUND_NAME		"lost+found"
> +#define YAFFS_LOSTNFOUND_PREFIX		"obj"
> +
> +
> +#define YAFFS_ROOT_MODE			0755
> +#define YAFFS_LOSTNFOUND_MODE		0700
> +
> +#define Y_CURRENT_TIME CURRENT_TIME.tv_sec
> +#define Y_TIME_CONVERT(x) (x).tv_sec
> +
> +#define compile_time_assertion(assertion) \
> +	({ int x = __builtin_choose_expr(assertion, 0, (void)0); (void) x; })

Have a look at the BUILD_BUG_ON macros in include/linux/kernel.h

> +
> +#ifndef Y_DUMP_STACK
> +#define Y_DUMP_STACK() dump_stack()
> +#endif

Do you need this wrapper? If you change YBUG to BUG then this can
probably go away as well.

> +#define yaffs_trace(msk, fmt, ...) do { \
> +	if (yaffs_trace_mask & (msk)) \
> +		printk(KERN_DEBUG "yaffs: " fmt "\n", ##__VA_ARGS__); \
> +} while (0)
> +
> +#ifndef YBUG
> +#define YBUG() do {\
> +	yaffs_trace(YAFFS_TRACE_BUG,\
> +		"bug " __FILE__ " %d",\
> +		__LINE__);\
> +	Y_DUMP_STACK();\
> +} while (0)

I think this should be replaced with just BUG. The naming here implies
that it has similar behaviour to BUG, which it does not. I'm guessing
that most of the places you are calling YBUG are unexpected states and
actually continuing is likely to result in further damage to the
filesystem. In general I think it would be better to just call BUG, have
the machine crash and get problems reported.

> +#endif
> +
> +#endif


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

[PATCH 10/10] Add yaffs2 file system: Hook in to Linux tree

[Charles Manning]

Change existing Makefile, Kconfig and MAINTAINERS.
Add yaffs2 specific Makefile and Kconfig

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 MAINTAINERS        |    7 ++
 fs/Kconfig         |    1 +
 fs/Makefile        |    1 +
 fs/yaffs2/Kconfig  |  161 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/Makefile |   17 ++++++
 5 files changed, 187 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/Kconfig
 create mode 100644 fs/yaffs2/Makefile

diff --git a/MAINTAINERS b/MAINTAINERS
index 64d7621..4cc7215 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6838,6 +6838,13 @@ L:	linux-serial@vger.kernel.org
 S:	Maintained
 F:	drivers/serial/uartlite.c
 
+YAFFS2 FLASH FILE SYSTEM
+M:	Charles Manning <cdhmanning@gmail.com>
+W:	http://www.yaffs.net/
+L:	yaffs@lists.aleph1.co.uk
+S:	Maintained
+F:	fs/yaffs2
+
 YAM DRIVER FOR AX.25
 M:	Jean-Paul Roubelat <jpr@f6fbb.org>
 L:	linux-hams@vger.kernel.org
diff --git a/fs/Kconfig b/fs/Kconfig
index 771f457..069abb1 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -176,6 +176,7 @@ source "fs/hfsplus/Kconfig"
 source "fs/befs/Kconfig"
 source "fs/bfs/Kconfig"
 source "fs/efs/Kconfig"
+source "fs/yaffs2/Kconfig"
 source "fs/jffs2/Kconfig"
 # UBIFS File system configuration
 source "fs/ubifs/Kconfig"
diff --git a/fs/Makefile b/fs/Makefile
index a7f7cef..e370ea5 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -121,3 +121,4 @@ obj-$(CONFIG_BTRFS_FS)		+= btrfs/
 obj-$(CONFIG_GFS2_FS)           += gfs2/
 obj-$(CONFIG_EXOFS_FS)          += exofs/
 obj-$(CONFIG_CEPH_FS)		+= ceph/
+obj-$(CONFIG_YAFFS_FS)		+= yaffs2/
diff --git a/fs/yaffs2/Kconfig b/fs/yaffs2/Kconfig
new file mode 100644
index 0000000..6354140
--- /dev/null
+++ b/fs/yaffs2/Kconfig
@@ -0,0 +1,161 @@
+#
+# YAFFS file system configurations
+#
+
+config YAFFS_FS
+	tristate "YAFFS2 file system support"
+	default n
+	depends on MTD_BLOCK
+	select YAFFS_YAFFS1
+	select YAFFS_YAFFS2
+	help
+	  YAFFS2, or Yet Another Flash Filing System, is a filing system
+	  optimised for NAND Flash chips.
+
+	  To compile the YAFFS2 file system support as a module, choose M
+	  here: the module will be called yaffs2.
+
+	  If unsure, say N.
+
+	  Further information on YAFFS2 is available at
+	  <http://www.aleph1.co.uk/yaffs/>.
+
+config YAFFS_YAFFS1
+	bool "512 byte / page devices"
+	depends on YAFFS_FS
+	default y
+	help
+	  Enable YAFFS1 support -- yaffs for 512 byte / page devices
+
+	  Not needed for 2K-page devices.
+
+	  If unsure, say Y.
+
+config YAFFS_9BYTE_TAGS
+	bool "Use older-style on-NAND data format with pageStatus byte"
+	depends on YAFFS_YAFFS1
+	default n
+	help
+
+	  Older-style on-NAND data format has a "pageStatus" byte to record
+	  chunk/page state.  This byte is zero when the page is discarded.
+	  Choose this option if you have existing on-NAND data using this
+	  format that you need to continue to support.  New data written
+	  also uses the older-style format.  Note: Use of this option
+	  generally requires that MTD's oob layout be adjusted to use the
+	  older-style format.  See notes on tags formats and MTD versions
+	  in yaffs_mtdif1.c.
+
+	  If unsure, say N.
+
+config YAFFS_DOES_ECC
+	bool "Lets Yaffs do its own ECC"
+	depends on YAFFS_FS && YAFFS_YAFFS1 && !YAFFS_9BYTE_TAGS
+	default n
+	help
+	  This enables Yaffs to use its own ECC functions instead of using
+	  the ones from the generic MTD-NAND driver.
+
+	  If unsure, say N.
+
+config YAFFS_ECC_WRONG_ORDER
+	bool "Use the same ecc byte order as Steven Hill's nand_ecc.c"
+	depends on YAFFS_FS && YAFFS_DOES_ECC && !YAFFS_9BYTE_TAGS
+	default n
+	help
+	  This makes yaffs_ecc.c use the same ecc byte order as Steven
+	  Hill's nand_ecc.c. If not set, then you get the same ecc byte
+	  order as SmartMedia.
+
+	  If unsure, say N.
+
+config YAFFS_YAFFS2
+	bool "2048 byte (or larger) / page devices"
+	depends on YAFFS_FS
+	default y
+	help
+	  Enable YAFFS2 support -- yaffs for >= 2K bytes per page devices
+
+	  If unsure, say Y.
+
+config YAFFS_AUTO_YAFFS2
+	bool "Autoselect yaffs2 format"
+	depends on YAFFS_YAFFS2
+	default y
+	help
+	  Without this, you need to explicitely use yaffs2 as the file
+	  system type. With this, you can say "yaffs" and yaffs or yaffs2
+	  will be used depending on the device page size (yaffs on
+	  512-byte page devices, yaffs2 on 2K page devices).
+
+	  If unsure, say Y.
+
+config YAFFS_DISABLE_TAGS_ECC
+	bool "Disable YAFFS from doing ECC on tags by default"
+	depends on YAFFS_FS && YAFFS_YAFFS2
+	default n
+	help
+	  This defaults Yaffs to using its own ECC calculations on tags instead of
+	  just relying on the MTD.
+	  This behavior can also be overridden with tags_ecc_on and
+	  tags_ecc_off mount options.
+
+	  If unsure, say N.
+
+config YAFFS_ALWAYS_CHECK_CHUNK_ERASED
+	bool "Force chunk erase check"
+	depends on YAFFS_FS
+	default n
+	help
+          Normally YAFFS only checks chunks before writing until an erased
+	  chunk is found. This helps to detect any partially written
+	  chunks that might have happened due to power loss.
+
+	  Enabling this forces on the test that chunks are erased in flash
+	  before writing to them. This takes more time but is potentially
+	  a bit more secure.
+
+	  Suggest setting Y during development and ironing out driver
+	  issues etc. Suggest setting to N if you want faster writing.
+
+	  If unsure, say Y.
+
+config YAFFS_EMPTY_LOST_AND_FOUND
+	bool "Empty lost and found on boot"
+	depends on YAFFS_FS
+	default n
+	help
+	  If this is enabled then the contents of lost and found is
+	  automatically dumped at mount.
+
+	  If unsure, say N.
+
+config YAFFS_DISABLE_BLOCK_REFRESHING
+	bool "Disable yaffs2 block refreshing"
+	depends on YAFFS_FS
+	default n
+	help
+	 If this is set, then block refreshing is disabled.
+	 Block refreshing infrequently refreshes the oldest block in
+	 a yaffs2 file system. This mechanism helps to refresh flash to
+	 mitigate against data loss. This is particularly useful for MLC.
+
+	  If unsure, say N.
+
+config YAFFS_DISABLE_BACKGROUND
+	bool "Disable yaffs2 background processing"
+	depends on YAFFS_FS
+	default n
+	help
+	 If this is set, then background processing is disabled.
+	 Background processing makes many foreground activities faster.
+
+	 If unsure, say N.
+
+config YAFFS_XATTR
+	bool "Enable yaffs2 xattr support"
+	depends on YAFFS_FS
+	default y
+	help
+	 If this is set then yaffs2 will provide xattr support.
+	 If unsure, say Y.
diff --git a/fs/yaffs2/Makefile b/fs/yaffs2/Makefile
new file mode 100644
index 0000000..e63a28a
--- /dev/null
+++ b/fs/yaffs2/Makefile
@@ -0,0 +1,17 @@
+#
+# Makefile for the linux YAFFS filesystem routines.
+#
+
+obj-$(CONFIG_YAFFS_FS) += yaffs.o
+
+yaffs-y := yaffs_ecc.o yaffs_vfs.o yaffs_guts.o yaffs_checkptrw.o
+yaffs-y += yaffs_packedtags1.o yaffs_packedtags2.o yaffs_nand.o
+yaffs-y += yaffs_tagscompat.o yaffs_tagsvalidity.o
+yaffs-y += yaffs_mtdif.o yaffs_mtdif1.o yaffs_mtdif2.o
+yaffs-y += yaffs_nameval.o yaffs_attribs.o
+yaffs-y += yaffs_allocator.o
+yaffs-y += yaffs_yaffs1.o
+yaffs-y += yaffs_yaffs2.o
+yaffs-y += yaffs_bitmap.o
+yaffs-y += yaffs_verify.o
+
-- 
1.7.1

Re: [PATCH 10/10] Add yaffs2 file system: Hook in to Linux tree

[Jesper Juhl]

Hi Charles,

A few minor comments below.


On Fri, 14 Jan 2011, Charles Manning wrote:

> Change existing Makefile, Kconfig and MAINTAINERS.
> Add yaffs2 specific Makefile and Kconfig
> 
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>
> ---
>  MAINTAINERS        |    7 ++
>  fs/Kconfig         |    1 +
>  fs/Makefile        |    1 +
>  fs/yaffs2/Kconfig  |  161 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/Makefile |   17 ++++++
>  5 files changed, 187 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/Kconfig
>  create mode 100644 fs/yaffs2/Makefile
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 64d7621..4cc7215 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6838,6 +6838,13 @@ L:	linux-serial@vger.kernel.org
>  S:	Maintained
>  F:	drivers/serial/uartlite.c
>  
> +YAFFS2 FLASH FILE SYSTEM
> +M:	Charles Manning <cdhmanning@gmail.com>
> +W:	http://www.yaffs.net/
> +L:	yaffs@lists.aleph1.co.uk
> +S:	Maintained
> +F:	fs/yaffs2
> +
>  YAM DRIVER FOR AX.25
>  M:	Jean-Paul Roubelat <jpr@f6fbb.org>
>  L:	linux-hams@vger.kernel.org
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 771f457..069abb1 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -176,6 +176,7 @@ source "fs/hfsplus/Kconfig"
>  source "fs/befs/Kconfig"
>  source "fs/bfs/Kconfig"
>  source "fs/efs/Kconfig"
> +source "fs/yaffs2/Kconfig"
>  source "fs/jffs2/Kconfig"
>  # UBIFS File system configuration
>  source "fs/ubifs/Kconfig"
> diff --git a/fs/Makefile b/fs/Makefile
> index a7f7cef..e370ea5 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -121,3 +121,4 @@ obj-$(CONFIG_BTRFS_FS)		+= btrfs/
>  obj-$(CONFIG_GFS2_FS)           += gfs2/
>  obj-$(CONFIG_EXOFS_FS)          += exofs/
>  obj-$(CONFIG_CEPH_FS)		+= ceph/
> +obj-$(CONFIG_YAFFS_FS)		+= yaffs2/
> diff --git a/fs/yaffs2/Kconfig b/fs/yaffs2/Kconfig
> new file mode 100644
> index 0000000..6354140
> --- /dev/null
> +++ b/fs/yaffs2/Kconfig
> @@ -0,0 +1,161 @@
> +#
> +# YAFFS file system configurations
> +#
> +
> +config YAFFS_FS
> +	tristate "YAFFS2 file system support"

"file system"

> +	default n
> +	depends on MTD_BLOCK
> +	select YAFFS_YAFFS1
> +	select YAFFS_YAFFS2
> +	help
> +	  YAFFS2, or Yet Another Flash Filing System, is a filing system

"filing system"

> +	  optimised for NAND Flash chips.
> +
> +	  To compile the YAFFS2 file system support as a module, choose M

"file system"

Why "file system" in some places and "filing system" in others?


> +	  here: the module will be called yaffs2.
> +
> +	  If unsure, say N.
> +
> +	  Further information on YAFFS2 is available at
> +	  <http://www.aleph1.co.uk/yaffs/>.
> +
> +config YAFFS_YAFFS1
> +	bool "512 byte / page devices"
> +	depends on YAFFS_FS
> +	default y
> +	help
> +	  Enable YAFFS1 support -- yaffs for 512 byte / page devices
> +
> +	  Not needed for 2K-page devices.
> +
> +	  If unsure, say Y.
> +
> +config YAFFS_9BYTE_TAGS
> +	bool "Use older-style on-NAND data format with pageStatus byte"
> +	depends on YAFFS_YAFFS1
> +	default n
> +	help
> +
> +	  Older-style on-NAND data format has a "pageStatus" byte to record
> +	  chunk/page state.  This byte is zero when the page is discarded.
> +	  Choose this option if you have existing on-NAND data using this
> +	  format that you need to continue to support.  New data written
> +	  also uses the older-style format.  Note: Use of this option
> +	  generally requires that MTD's oob layout be adjusted to use the
> +	  older-style format.  See notes on tags formats and MTD versions
> +	  in yaffs_mtdif1.c.
> +
> +	  If unsure, say N.
> +
> +config YAFFS_DOES_ECC
> +	bool "Lets Yaffs do its own ECC"

Shouldn't this read "Let Yaffs do its own ECC" ?
Ohh and why the different capitalization? Here it is "Yaffs", elsewhere it 
it is "YAFFS".


> +	depends on YAFFS_FS && YAFFS_YAFFS1 && !YAFFS_9BYTE_TAGS
> +	default n
> +	help
> +	  This enables Yaffs to use its own ECC functions instead of using

Again - "Yaffs" vs "YAFFS". Personally I'd say "pick one".


> +	  the ones from the generic MTD-NAND driver.
> +
> +	  If unsure, say N.
> +
> +config YAFFS_ECC_WRONG_ORDER
> +	bool "Use the same ecc byte order as Steven Hill's nand_ecc.c"

Shouldn't this be "Use the same ECC byte order ..." ?


> +	depends on YAFFS_FS && YAFFS_DOES_ECC && !YAFFS_9BYTE_TAGS
> +	default n
> +	help
> +	  This makes yaffs_ecc.c use the same ecc byte order as Steven
> +	  Hill's nand_ecc.c. If not set, then you get the same ecc byte

ECC?


> +	  order as SmartMedia.
> +
> +	  If unsure, say N.
> +
> +config YAFFS_YAFFS2
> +	bool "2048 byte (or larger) / page devices"
> +	depends on YAFFS_FS
> +	default y
> +	help
> +	  Enable YAFFS2 support -- yaffs for >= 2K bytes per page devices

YAFFS vs Yaffs vs yaffs... - elsewhere as well, not pointing this out for 
the rest of the patch..


> +
> +	  If unsure, say Y.
> +
> +config YAFFS_AUTO_YAFFS2
> +	bool "Autoselect yaffs2 format"
> +	depends on YAFFS_YAFFS2
> +	default y
> +	help
> +	  Without this, you need to explicitely use yaffs2 as the file
> +	  system type. With this, you can say "yaffs" and yaffs or yaffs2
> +	  will be used depending on the device page size (yaffs on
> +	  512-byte page devices, yaffs2 on 2K page devices).
> +
> +	  If unsure, say Y.
> +
> +config YAFFS_DISABLE_TAGS_ECC
> +	bool "Disable YAFFS from doing ECC on tags by default"
> +	depends on YAFFS_FS && YAFFS_YAFFS2
> +	default n
> +	help
> +	  This defaults Yaffs to using its own ECC calculations on tags instead of
> +	  just relying on the MTD.
> +	  This behavior can also be overridden with tags_ecc_on and
> +	  tags_ecc_off mount options.
> +
> +	  If unsure, say N.
> +
> +config YAFFS_ALWAYS_CHECK_CHUNK_ERASED
> +	bool "Force chunk erase check"
> +	depends on YAFFS_FS
> +	default n
> +	help
> +          Normally YAFFS only checks chunks before writing until an erased

You don't have this extra indentation at the start of the first line for 
other help entries...


> +	  chunk is found. This helps to detect any partially written
> +	  chunks that might have happened due to power loss.
> +
> +	  Enabling this forces on the test that chunks are erased in flash
> +	  before writing to them. This takes more time but is potentially
> +	  a bit more secure.
> +
> +	  Suggest setting Y during development and ironing out driver

Perhaps "It is suggested to set this to Y during development ..." or "We 
recommend setting this to Y during .." - the current wording is a little 
clumsy IMHO.

> +	  issues etc. Suggest setting to N if you want faster writing.
> +

Same for "N".


> +	  If unsure, say Y.
> +
> +config YAFFS_EMPTY_LOST_AND_FOUND
> +	bool "Empty lost and found on boot"
> +	depends on YAFFS_FS
> +	default n
> +	help
> +	  If this is enabled then the contents of lost and found is
> +	  automatically dumped at mount.

Hmm, isn't the dir named "lost+found", not "lost and found" ?


> +
> +	  If unsure, say N.
> +
> +config YAFFS_DISABLE_BLOCK_REFRESHING
> +	bool "Disable yaffs2 block refreshing"
> +	depends on YAFFS_FS
> +	default n
> +	help
> +	 If this is set, then block refreshing is disabled.
> +	 Block refreshing infrequently refreshes the oldest block in
> +	 a yaffs2 file system. This mechanism helps to refresh flash to
> +	 mitigate against data loss. This is particularly useful for MLC.
> +
> +	  If unsure, say N.
> +
> +config YAFFS_DISABLE_BACKGROUND
> +	bool "Disable yaffs2 background processing"
> +	depends on YAFFS_FS
> +	default n
> +	help
> +	 If this is set, then background processing is disabled.
> +	 Background processing makes many foreground activities faster.
> +
> +	 If unsure, say N.
> +
> +config YAFFS_XATTR
> +	bool "Enable yaffs2 xattr support"
> +	depends on YAFFS_FS
> +	default y
> +	help
> +	 If this is set then yaffs2 will provide xattr support.
> +	 If unsure, say Y.

You usually have a blank line before the "If unsure, say X" line, but not 
here - I think you should have.


> diff --git a/fs/yaffs2/Makefile b/fs/yaffs2/Makefile
> new file mode 100644
> index 0000000..e63a28a
> --- /dev/null
> +++ b/fs/yaffs2/Makefile
> @@ -0,0 +1,17 @@
> +#
> +# Makefile for the linux YAFFS filesystem routines.
> +#
> +
> +obj-$(CONFIG_YAFFS_FS) += yaffs.o
> +
> +yaffs-y := yaffs_ecc.o yaffs_vfs.o yaffs_guts.o yaffs_checkptrw.o
> +yaffs-y += yaffs_packedtags1.o yaffs_packedtags2.o yaffs_nand.o
> +yaffs-y += yaffs_tagscompat.o yaffs_tagsvalidity.o
> +yaffs-y += yaffs_mtdif.o yaffs_mtdif1.o yaffs_mtdif2.o
> +yaffs-y += yaffs_nameval.o yaffs_attribs.o
> +yaffs-y += yaffs_allocator.o
> +yaffs-y += yaffs_yaffs1.o
> +yaffs-y += yaffs_yaffs2.o
> +yaffs-y += yaffs_bitmap.o
> +yaffs-y += yaffs_verify.o
> +
> 

-- 
Jesper Juhl <jj@chaosbits.net>            http://www.chaosbits.net/
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please.

[PATCH 0/10] Add yaffs2 file system: Fifth patchset

[Charles Manning]

This is the fifth submission of a yaffs2 patchset.

I would like to thank everyone that has given comments so far, with
particular mention of Ryan Mallon at Bluewater Systems.

I would like to thank CELF (now part of Linux Foundation) and Google
for sponsoring the effort to get yaffs2 mainlined.

This code is patched from 7ad3c1635865d2e214eaef02ec53f0eb3956daa6
at git://www.aleph1.co.uk/yaffs2.

This patch set takes onboard almost all of Ryan's comments to make the
code paths cleaner.

This code ran various tests for the whole night with no problems seen.

Comments/feedback welcome, but I'm hopefully getting pretty close to
acceptance :-).

-- Charles

[PATCH 09/10] Add yaffs2 file system: Linux glue code

[Charles Manning]

Signed-off-by: Charles Manning <cdhmanning@gmail.com>
---
 fs/yaffs2/yaffs_linux.h |   41 +
 fs/yaffs2/yaffs_vfs.c   | 2745 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/yaffs2/yportenv.h    |   59 +
 3 files changed, 2845 insertions(+), 0 deletions(-)
 create mode 100644 fs/yaffs2/yaffs_linux.h
 create mode 100644 fs/yaffs2/yaffs_vfs.c
 create mode 100644 fs/yaffs2/yportenv.h

diff --git a/fs/yaffs2/yaffs_linux.h b/fs/yaffs2/yaffs_linux.h
new file mode 100644
index 0000000..8c522c8
--- /dev/null
+++ b/fs/yaffs2/yaffs_linux.h
@@ -0,0 +1,41 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2011 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_LINUX_H__
+#define __YAFFS_LINUX_H__
+
+#include "yportenv.h"
+
+struct yaffs_linux_context {
+	struct list_head context_list;	/* List of these we have mounted */
+	struct yaffs_dev *dev;
+	struct super_block *super;
+	struct task_struct *bg_thread;	/* Background thread for this device */
+	int bg_running;
+	struct mutex gross_lock;	/* Gross locking mutex*/
+	u8 *spare_buffer;	/* For mtdif2 use. Don't know the buffer size
+				 * at compile time so we have to allocate it.
+				 */
+	struct list_head search_contexts;
+	void (*put_super_fn) (struct super_block *sb);
+
+	struct task_struct *readdir_process;
+	unsigned mount_id;
+};
+
+#define yaffs_dev_to_lc(dev) ((struct yaffs_linux_context *)((dev)->os_context))
+#define yaffs_dev_to_mtd(dev) ((struct mtd_info *)((dev)->driver_context))
+
+#endif
diff --git a/fs/yaffs2/yaffs_vfs.c b/fs/yaffs2/yaffs_vfs.c
new file mode 100644
index 0000000..724bd3f
--- /dev/null
+++ b/fs/yaffs2/yaffs_vfs.c
@@ -0,0 +1,2745 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2011 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ * Acknowledgements:
+ * Luc van OostenRyck for numerous patches.
+ * Nick Bane for numerous patches.
+ * Nick Bane for 2.5/2.6 integration.
+ * Andras Toth for mknod rdev issue.
+ * Michael Fischer for finding the problem with inode inconsistency.
+ * Some code bodily lifted from JFFS
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ *
+ * This is the file system front-end to YAFFS that hooks it up to
+ * the VFS.
+ *
+ * Special notes:
+ * >> 2.4: sb->u.generic_sbp points to the struct yaffs_dev associated with
+ *         this superblock
+ * >> 2.6: sb->s_fs_info  points to the struct yaffs_dev associated with this
+ *         superblock
+ * >> inode->u.generic_ip points to the associated struct yaffs_obj.
+ */
+
+/*
+ * NB There are two variants of Linux VFS glue code. This variant supports
+ * a single version and should not include any multi-version code.
+ */
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/proc_fs.h>
+#include <linux/smp_lock.h>
+#include <linux/pagemap.h>
+#include <linux/mtd/mtd.h>
+#include <linux/interrupt.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/namei.h>
+#include <linux/exportfs.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+#include <linux/freezer.h>
+#include <asm/div64.h>
+#include <linux/statfs.h>
+#include <linux/uaccess.h>
+#include <linux/mtd/mtd.h>
+
+#include "yportenv.h"
+#include "yaffs_trace.h"
+#include "yaffs_guts.h"
+#include "yaffs_attribs.h"
+#include "yaffs_linux.h"
+#include "yaffs_mtdif.h"
+#include "yaffs_mtdif1.h"
+#include "yaffs_mtdif2.h"
+
+unsigned int yaffs_trace_mask = YAFFS_TRACE_BAD_BLOCKS | YAFFS_TRACE_ALWAYS;
+unsigned int yaffs_wr_attempts = YAFFS_WR_ATTEMPTS;
+unsigned int yaffs_auto_checkpoint = 1;
+unsigned int yaffs_gc_control = 1;
+unsigned int yaffs_bg_enable = 1;
+
+/* Module Parameters */
+module_param(yaffs_trace_mask, uint, 0644);
+module_param(yaffs_wr_attempts, uint, 0644);
+module_param(yaffs_auto_checkpoint, uint, 0644);
+module_param(yaffs_gc_control, uint, 0644);
+module_param(yaffs_bg_enable, uint, 0644);
+
+#define yaffs_devname(sb, buf)	bdevname(sb->s_bdev, buf)
+
+static uint32_t YCALCBLOCKS(uint64_t partition_size, uint32_t block_size)
+{
+	uint64_t result = partition_size;
+
+	do_div(result, block_size);
+	return (uint32_t) result;
+}
+
+#define yaffs_inode_to_obj_lv(iptr) ((iptr)->i_private)
+#define yaffs_inode_to_obj(iptr)\
+	((struct yaffs_obj *)(yaffs_inode_to_obj_lv(iptr)))
+#define yaffs_dentry_to_obj(dptr) yaffs_inode_to_obj((dptr)->d_inode)
+#define yaffs_super_to_dev(sb)	((struct yaffs_dev *)sb->s_fs_info)
+
+#define update_dir_time(dir) do {\
+			(dir)->i_ctime = (dir)->i_mtime = CURRENT_TIME; \
+		} while (0)
+
+
+static unsigned yaffs_gc_control_callback(struct yaffs_dev *dev)
+{
+	return yaffs_gc_control;
+}
+
+static void yaffs_gross_lock(struct yaffs_dev *dev)
+{
+	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locking %p", current);
+	mutex_lock(&(yaffs_dev_to_lc(dev)->gross_lock));
+	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locked %p", current);
+}
+
+static void yaffs_gross_unlock(struct yaffs_dev *dev)
+{
+	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs unlocking %p", current);
+	mutex_unlock(&(yaffs_dev_to_lc(dev)->gross_lock));
+}
+
+static void yaffs_fill_inode_from_obj(struct inode *inode,
+				      struct yaffs_obj *obj);
+
+static struct inode *yaffs_iget(struct super_block *sb, unsigned long ino)
+{
+	struct inode *inode;
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_iget for %lu", ino);
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+
+	/* NB This is called as a side effect of other functions, but
+	 * we had to release the lock to prevent deadlocks, so
+	 * need to lock again.
+	 */
+
+	yaffs_gross_lock(dev);
+
+	obj = yaffs_find_by_number(dev, inode->i_ino);
+	yaffs_fill_inode_from_obj(inode, obj);
+
+	yaffs_gross_unlock(dev);
+
+	unlock_new_inode(inode);
+	return inode;
+}
+
+struct inode *yaffs_get_inode(struct super_block *sb, int mode, int dev,
+			      struct yaffs_obj *obj)
+{
+	struct inode *inode;
+
+	if (!sb) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_get_inode for NULL super_block!!");
+		return NULL;
+
+	}
+
+	if (!obj) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_get_inode for NULL object!!");
+		return NULL;
+
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_get_inode for object %d",
+		obj->obj_id);
+
+	inode = yaffs_iget(sb, obj->obj_id);
+	if (IS_ERR(inode))
+		return NULL;
+
+	/* NB Side effect: iget calls back to yaffs_read_inode(). */
+	/* iget also increments the inode's i_count */
+	/* NB You can't be holding gross_lock or deadlock will happen! */
+
+	return inode;
+}
+
+static int yaffs_mknod(struct inode *dir, struct dentry *dentry, int mode,
+		       dev_t rdev)
+{
+	struct inode *inode;
+	struct yaffs_obj *obj = NULL;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *parent = yaffs_inode_to_obj(dir);
+	int error;
+	uid_t uid = current->cred->fsuid;
+	gid_t gid =
+	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
+
+	if ((dir->i_mode & S_ISGID) && S_ISDIR(mode))
+		mode |= S_ISGID;
+
+	if (!parent) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_mknod: could not get parent object");
+		return -EPERM;
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_mknod: parent object %d type %d",
+			parent->obj_id, parent->variant_type);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_mknod: making oject for %s, mode %x dev %x",
+		dentry->d_name.name, mode, rdev);
+
+	dev = parent->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	if (yaffs_get_n_free_chunks(dev) < 1) {
+		error = -ENOSPC;
+		goto err_out;
+	}
+
+	switch (mode & S_IFMT) {
+	default:
+		/* Special (socket, fifo, device...) */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making special");
+		obj =
+		    yaffs_create_special(parent, dentry->d_name.name, mode, uid,
+					 gid, old_encode_dev(rdev));
+		break;
+	case S_IFREG:		/* file          */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making file");
+		obj = yaffs_create_file(parent, dentry->d_name.name, mode, uid,
+					gid);
+		break;
+	case S_IFDIR:		/* directory */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making directory");
+		obj = yaffs_create_dir(parent, dentry->d_name.name, mode,
+				       uid, gid);
+		break;
+	case S_IFLNK:		/* symlink */
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making symlink");
+		obj = NULL;	/* Do we ever get here? */
+		break;
+	}
+
+	if (!obj) {
+		error = -ENOMEM;
+		goto err_out;
+	}
+
+	/* Can not call yaffs_get_inode() with gross lock held */
+	yaffs_gross_unlock(dev);
+
+
+	inode = yaffs_get_inode(dir->i_sb, mode, rdev, obj);
+	d_instantiate(dentry, inode);
+	update_dir_time(dir);
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_mknod created object %d count = %d",
+		obj->obj_id, atomic_read(&inode->i_count));
+	yaffs_fill_inode_from_obj(dir, parent);
+	return 0;
+
+err_out:
+	yaffs_gross_unlock(dev);
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod error %d", error);
+	return error;
+
+}
+
+static int yaffs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+	return yaffs_mknod(dir, dentry, mode | S_IFDIR, 0);
+}
+
+static int yaffs_create(struct inode *dir, struct dentry *dentry, int mode,
+			struct nameidata *n)
+{
+	return yaffs_mknod(dir, dentry, mode | S_IFREG, 0);
+}
+
+static int yaffs_link(struct dentry *old_dentry, struct inode *dir,
+		      struct dentry *dentry)
+{
+	struct inode *inode = old_dentry->d_inode;
+	struct yaffs_obj *obj = NULL;
+	struct yaffs_obj *link = NULL;
+	struct yaffs_dev *dev;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_link");
+
+	obj = yaffs_inode_to_obj(inode);
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	if (!S_ISDIR(inode->i_mode))	/* Don't link directories */
+		link =
+		    yaffs_link_obj(yaffs_inode_to_obj(dir), dentry->d_name.name,
+				   obj);
+
+	if (link) {
+		old_dentry->d_inode->i_nlink = yaffs_get_obj_link_count(obj);
+		d_instantiate(dentry, old_dentry->d_inode);
+		atomic_inc(&old_dentry->d_inode->i_count);
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_link link count %d i_count %d",
+			old_dentry->d_inode->i_nlink,
+			atomic_read(&old_dentry->d_inode->i_count));
+	}
+
+	yaffs_gross_unlock(dev);
+
+	if (link) {
+		update_dir_time(dir);
+		return 0;
+	}
+
+	return -EPERM;
+}
+
+static int yaffs_symlink(struct inode *dir, struct dentry *dentry,
+			 const char *symname)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	struct inode *inode;
+	uid_t uid = current->cred->fsuid;
+	gid_t gid =
+	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_symlink");
+
+	dev = yaffs_inode_to_obj(dir)->my_dev;
+	yaffs_gross_lock(dev);
+	obj = yaffs_create_symlink(yaffs_inode_to_obj(dir), dentry->d_name.name,
+				   S_IFLNK | S_IRWXUGO, uid, gid, symname);
+	yaffs_gross_unlock(dev);
+
+	if (!obj) {
+		yaffs_trace(YAFFS_TRACE_OS, "symlink not created");
+		return -ENOMEM;
+	}
+
+	inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
+	d_instantiate(dentry, inode);
+	update_dir_time(dir);
+	yaffs_trace(YAFFS_TRACE_OS, "symlink created OK");
+
+	return 0;
+}
+
+static struct dentry *yaffs_lookup(struct inode *dir, struct dentry *dentry,
+				   struct nameidata *n)
+{
+	struct yaffs_obj *obj;
+	struct inode *inode = NULL;
+	struct yaffs_dev *dev = yaffs_inode_to_obj(dir)->my_dev;
+
+	if (current != yaffs_dev_to_lc(dev)->readdir_process)
+		yaffs_gross_lock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_lookup for %d:%s",
+		yaffs_inode_to_obj(dir)->obj_id, dentry->d_name.name);
+
+	obj = yaffs_find_by_name(yaffs_inode_to_obj(dir), dentry->d_name.name);
+
+	obj = yaffs_get_equivalent_obj(obj);	/* in case it was a hardlink */
+
+	/* Can't hold gross lock when calling yaffs_get_inode() */
+	if (current != yaffs_dev_to_lc(dev)->readdir_process)
+		yaffs_gross_unlock(dev);
+
+	if (obj) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_lookup found %d", obj->obj_id);
+
+		inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
+
+		if (inode) {
+			yaffs_trace(YAFFS_TRACE_OS, "yaffs_loookup dentry");
+			d_add(dentry, inode);
+			/* return dentry; */
+			return NULL;
+		}
+
+	} else {
+		yaffs_trace(YAFFS_TRACE_OS, "yaffs_lookup not found");
+
+	}
+
+	d_add(dentry, inode);
+
+	return NULL;
+}
+
+static int yaffs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	int ret_val;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_unlink %d:%s",
+		(int)(dir->i_ino), dentry->d_name.name);
+	obj = yaffs_inode_to_obj(dir);
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	ret_val = yaffs_unlinker(obj, dentry->d_name.name);
+
+	if (ret_val == YAFFS_OK) {
+		dentry->d_inode->i_nlink--;
+		dir->i_version++;
+		yaffs_gross_unlock(dev);
+		mark_inode_dirty(dentry->d_inode);
+		update_dir_time(dir);
+		return 0;
+	}
+	yaffs_gross_unlock(dev);
+	return -ENOTEMPTY;
+}
+
+static int yaffs_sync_object(struct file *file, int datasync)
+{
+
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	struct dentry *dentry = file->f_path.dentry;
+
+	obj = yaffs_dentry_to_obj(dentry);
+
+	dev = obj->my_dev;
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC, "yaffs_sync_object");
+	yaffs_gross_lock(dev);
+	yaffs_flush_file(obj, 1, datasync);
+	yaffs_gross_unlock(dev);
+	return 0;
+}
+/*
+ * The VFS layer already does all the dentry stuff for rename.
+ *
+ * NB: POSIX says you can rename an object over an old object of the same name
+ */
+static int yaffs_rename(struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir, struct dentry *new_dentry)
+{
+	struct yaffs_dev *dev;
+	int ret_val = YAFFS_FAIL;
+	struct yaffs_obj *target;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_rename");
+	dev = yaffs_inode_to_obj(old_dir)->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	/* Check if the target is an existing directory that is not empty. */
+	target = yaffs_find_by_name(yaffs_inode_to_obj(new_dir),
+				    new_dentry->d_name.name);
+
+	if (target && target->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY &&
+	    !list_empty(&target->variant.dir_variant.children)) {
+
+		yaffs_trace(YAFFS_TRACE_OS, "target is non-empty dir");
+
+		ret_val = YAFFS_FAIL;
+	} else {
+		/* Now does unlinking internally using shadowing mechanism */
+		yaffs_trace(YAFFS_TRACE_OS, "calling yaffs_rename_obj");
+
+		ret_val = yaffs_rename_obj(yaffs_inode_to_obj(old_dir),
+					   old_dentry->d_name.name,
+					   yaffs_inode_to_obj(new_dir),
+					   new_dentry->d_name.name);
+	}
+	yaffs_gross_unlock(dev);
+
+	if (ret_val == YAFFS_OK) {
+		if (target) {
+			new_dentry->d_inode->i_nlink--;
+			mark_inode_dirty(new_dentry->d_inode);
+		}
+
+		update_dir_time(old_dir);
+		if (old_dir != new_dir)
+			update_dir_time(new_dir);
+		return 0;
+	} else {
+		return -ENOTEMPTY;
+	}
+}
+
+static int yaffs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = dentry->d_inode;
+	int error = 0;
+	struct yaffs_dev *dev;
+	int result;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_setattr of object %d",
+		yaffs_inode_to_obj(inode)->obj_id);
+
+	/* Fail if a requested resize >= 2GB */
+	if (attr->ia_valid & ATTR_SIZE && (attr->ia_size >> 31))
+		error = -EINVAL;
+
+	if (!error)
+		error = inode_change_ok(inode, attr);
+
+	if (!error) {
+		setattr_copy(inode, attr);
+		yaffs_trace(YAFFS_TRACE_OS, "inode_setattr called");
+		if (attr->ia_valid & ATTR_SIZE) {
+			truncate_setsize(inode, attr->ia_size);
+			inode->i_blocks = (inode->i_size + 511) >> 9;
+		}
+		dev = yaffs_inode_to_obj(inode)->my_dev;
+		if (attr->ia_valid & ATTR_SIZE) {
+			yaffs_trace(YAFFS_TRACE_OS, "resize to %d(%x)",
+					   (int)(attr->ia_size),
+					   (int)(attr->ia_size));
+		}
+
+		yaffs_gross_lock(dev);
+		result = yaffs_set_attribs(yaffs_inode_to_obj(inode), attr);
+		if (result != YAFFS_OK)
+			error = -EPERM;
+		yaffs_gross_unlock(dev);
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setattr done returning %d", error);
+
+	return error;
+}
+
+#ifdef CONFIG_YAFFS_XATTR
+static int yaffs_setxattr(struct dentry *dentry, const char *name,
+		   const void *value, size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr of object %d", obj->obj_id);
+
+	dev = obj->my_dev;
+	yaffs_gross_lock(dev);
+	error = yaffs_set_xattrib(obj, name, value, size, flags);
+	yaffs_gross_unlock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr done returning %d", error);
+
+	return error;
+}
+
+static ssize_t yaffs_getxattr(struct dentry *dentry, const char *name,
+				void *buff, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_getxattr \"%s\" from object %d",
+		name, obj->obj_id);
+
+	dev = obj->my_dev;
+	yaffs_gross_lock(dev);
+	error = yaffs_get_xattrib(obj, name, buff, size);
+	yaffs_gross_unlock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_getxattr done returning %d", error);
+
+	return error;
+}
+
+static int yaffs_removexattr(struct dentry *dentry, const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_removexattr of object %d", obj->obj_id);
+
+	dev = obj->my_dev;
+	yaffs_gross_lock(dev);
+	error = yaffs_remove_xattrib(obj, name);
+	yaffs_gross_unlock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_removexattr done returning %d", error);
+
+	return error;
+}
+
+static ssize_t yaffs_listxattr(struct dentry *dentry, char *buff, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+	struct yaffs_dev *dev;
+	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_listxattr of object %d", obj->obj_id);
+
+	dev = obj->my_dev;
+	yaffs_gross_lock(dev);
+	error = yaffs_list_xattrib(obj, buff, size);
+	yaffs_gross_unlock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_listxattr done returning %d", error);
+
+	return error;
+}
+
+#endif
+
+static const struct inode_operations yaffs_dir_inode_operations = {
+	.create = yaffs_create,
+	.lookup = yaffs_lookup,
+	.link = yaffs_link,
+	.unlink = yaffs_unlink,
+	.symlink = yaffs_symlink,
+	.mkdir = yaffs_mkdir,
+	.rmdir = yaffs_unlink,
+	.mknod = yaffs_mknod,
+	.rename = yaffs_rename,
+	.setattr = yaffs_setattr,
+#ifdef CONFIG_YAFFS_XATTR
+	.setxattr = yaffs_setxattr,
+	.getxattr = yaffs_getxattr,
+	.listxattr = yaffs_listxattr,
+	.removexattr = yaffs_removexattr,
+#endif
+};
+/*-----------------------------------------------------------------*/
+/* Directory search context allows us to unlock access to yaffs during
+ * filldir without causing problems with the directory being modified.
+ * This is similar to the tried and tested mechanism used in yaffs direct.
+ *
+ * A search context iterates along a doubly linked list of siblings in the
+ * directory. If the iterating object is deleted then this would corrupt
+ * the list iteration, likely causing a crash. The search context avoids
+ * this by using the remove_obj_fn to move the search context to the
+ * next object before the object is deleted.
+ *
+ * Many readdirs (and thus seach conexts) may be alive simulateously so
+ * each struct yaffs_dev has a list of these.
+ *
+ * A seach context lives for the duration of a readdir.
+ *
+ * All these functions must be called while yaffs is locked.
+ */
+
+struct yaffs_search_context {
+	struct yaffs_dev *dev;
+	struct yaffs_obj *dir_obj;
+	struct yaffs_obj *next_return;
+	struct list_head others;
+};
+
+/*
+ * yaffs_new_search() creates a new search context, initialises it and
+ * adds it to the device's search context list.
+ *
+ * Called at start of readdir.
+ */
+static struct yaffs_search_context *yaffs_new_search(struct yaffs_obj *dir)
+{
+	struct yaffs_dev *dev = dir->my_dev;
+	struct yaffs_search_context *sc =
+	    kmalloc(sizeof(struct yaffs_search_context), GFP_NOFS);
+
+	if (!sc)
+		return NULL;
+
+	sc->dir_obj = dir;
+	sc->dev = dev;
+	if (list_empty(&sc->dir_obj->variant.dir_variant.children))
+		sc->next_return = NULL;
+	else
+		sc->next_return =
+		    list_entry(dir->variant.dir_variant.children.next,
+			       struct yaffs_obj, siblings);
+	INIT_LIST_HEAD(&sc->others);
+	list_add(&sc->others, &(yaffs_dev_to_lc(dev)->search_contexts));
+
+	return sc;
+}
+
+/*
+ * yaffs_search_end() disposes of a search context and cleans up.
+ */
+static void yaffs_search_end(struct yaffs_search_context *sc)
+{
+	if (sc) {
+		list_del(&sc->others);
+		kfree(sc);
+	}
+}
+
+/*
+ * yaffs_search_advance() moves a search context to the next object.
+ * Called when the search iterates or when an object removal causes
+ * the search context to be moved to the next object.
+ */
+static void yaffs_search_advance(struct yaffs_search_context *sc)
+{
+	if (!sc)
+		return;
+
+	if (sc->next_return == NULL ||
+	    list_empty(&sc->dir_obj->variant.dir_variant.children))
+		sc->next_return = NULL;
+	else {
+		struct list_head *next = sc->next_return->siblings.next;
+
+		if (next == &sc->dir_obj->variant.dir_variant.children)
+			sc->next_return = NULL;	/* end of list */
+		else
+			sc->next_return =
+			    list_entry(next, struct yaffs_obj, siblings);
+	}
+}
+
+/*
+ * yaffs_remove_obj_callback() is called when an object is unlinked.
+ * We check open search contexts and advance any which are currently
+ * on the object being iterated.
+ */
+static void yaffs_remove_obj_callback(struct yaffs_obj *obj)
+{
+
+	struct list_head *i;
+	struct yaffs_search_context *sc;
+	struct list_head *search_contexts =
+	    &(yaffs_dev_to_lc(obj->my_dev)->search_contexts);
+
+	/* Iterate through the directory search contexts.
+	 * If any are currently on the object being removed, then advance
+	 * the search context to the next object to prevent a hanging pointer.
+	 */
+	list_for_each(i, search_contexts) {
+		sc = list_entry(i, struct yaffs_search_context, others);
+		if (sc->next_return == obj)
+			yaffs_search_advance(sc);
+	}
+
+}
+
+static int yaffs_readdir(struct file *f, void *dirent, filldir_t filldir)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	struct yaffs_search_context *sc;
+	struct inode *inode = f->f_dentry->d_inode;
+	unsigned long offset, curoffs;
+	struct yaffs_obj *l;
+	int ret_val = 0;
+	char name[YAFFS_MAX_NAME_LENGTH + 1];
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	yaffs_dev_to_lc(dev)->readdir_process = current;
+
+	offset = f->f_pos;
+
+	sc = yaffs_new_search(obj);
+	if (!sc) {
+		ret_val = -ENOMEM;
+		goto out;
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_readdir: starting at %d", (int)offset);
+
+	if (offset == 0) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_readdir: entry . ino %d",
+			(int)inode->i_ino);
+		yaffs_gross_unlock(dev);
+		if (filldir(dirent, ".", 1, offset, inode->i_ino, DT_DIR) < 0) {
+			yaffs_gross_lock(dev);
+			goto out;
+		}
+		yaffs_gross_lock(dev);
+		offset++;
+		f->f_pos++;
+	}
+	if (offset == 1) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_readdir: entry .. ino %d",
+			(int)f->f_dentry->d_parent->d_inode->i_ino);
+		yaffs_gross_unlock(dev);
+		if (filldir(dirent, "..", 2, offset,
+			    f->f_dentry->d_parent->d_inode->i_ino,
+			    DT_DIR) < 0) {
+			yaffs_gross_lock(dev);
+			goto out;
+		}
+		yaffs_gross_lock(dev);
+		offset++;
+		f->f_pos++;
+	}
+
+	curoffs = 1;
+
+	/* If the directory has changed since the open or last call to
+	   readdir, rewind to after the 2 canned entries. */
+	if (f->f_version != inode->i_version) {
+		offset = 2;
+		f->f_pos = offset;
+		f->f_version = inode->i_version;
+	}
+
+	while (sc->next_return) {
+		curoffs++;
+		l = sc->next_return;
+		if (curoffs >= offset) {
+			int this_inode = yaffs_get_obj_inode(l);
+			int this_type = yaffs_get_obj_type(l);
+
+			yaffs_get_obj_name(l, name, YAFFS_MAX_NAME_LENGTH + 1);
+			yaffs_trace(YAFFS_TRACE_OS,
+				"yaffs_readdir: %s inode %d",
+				name, yaffs_get_obj_inode(l));
+
+			yaffs_gross_unlock(dev);
+
+			if (filldir(dirent,
+				    name,
+				    strlen(name),
+				    offset, this_inode, this_type) < 0) {
+				yaffs_gross_lock(dev);
+				goto out;
+			}
+
+			yaffs_gross_lock(dev);
+
+			offset++;
+			f->f_pos++;
+		}
+		yaffs_search_advance(sc);
+	}
+
+out:
+	yaffs_search_end(sc);
+	yaffs_dev_to_lc(dev)->readdir_process = NULL;
+	yaffs_gross_unlock(dev);
+
+	return ret_val;
+}
+
+static const struct file_operations yaffs_dir_operations = {
+	.read = generic_read_dir,
+	.readdir = yaffs_readdir,
+	.fsync = yaffs_sync_object,
+	.llseek = generic_file_llseek,
+};
+
+
+
+static int yaffs_file_flush(struct file *file, fl_owner_t id)
+{
+	struct yaffs_obj *obj = yaffs_dentry_to_obj(file->f_dentry);
+	struct yaffs_dev *dev = obj->my_dev;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_file_flush object %d (%s)",
+		obj->obj_id, obj->dirty ? "dirty" : "clean");
+
+	yaffs_gross_lock(dev);
+
+	yaffs_flush_file(obj, 1, 0);
+
+	yaffs_gross_unlock(dev);
+
+	return 0;
+}
+
+static const struct file_operations yaffs_file_operations = {
+	.read = do_sync_read,
+	.write = do_sync_write,
+	.aio_read = generic_file_aio_read,
+	.aio_write = generic_file_aio_write,
+	.mmap = generic_file_mmap,
+	.flush = yaffs_file_flush,
+	.fsync = yaffs_sync_object,
+	.splice_read = generic_file_splice_read,
+	.splice_write = generic_file_splice_write,
+	.llseek = generic_file_llseek,
+};
+
+
+/* ExportFS support */
+static struct inode *yaffs2_nfs_get_inode(struct super_block *sb, uint64_t ino,
+					  uint32_t generation)
+{
+	return yaffs_iget(sb, ino);
+}
+
+static struct dentry *yaffs2_fh_to_dentry(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
+{
+	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+				    yaffs2_nfs_get_inode);
+}
+
+static struct dentry *yaffs2_fh_to_parent(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
+{
+	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+				    yaffs2_nfs_get_inode);
+}
+
+struct dentry *yaffs2_get_parent(struct dentry *dentry)
+{
+
+	struct super_block *sb = dentry->d_inode->i_sb;
+	struct dentry *parent = ERR_PTR(-ENOENT);
+	struct inode *inode;
+	unsigned long parent_ino;
+	struct yaffs_obj *d_obj;
+	struct yaffs_obj *parent_obj;
+
+	d_obj = yaffs_inode_to_obj(dentry->d_inode);
+
+	if (d_obj) {
+		parent_obj = d_obj->parent;
+		if (parent_obj) {
+			parent_ino = yaffs_get_obj_inode(parent_obj);
+			inode = yaffs_iget(sb, parent_ino);
+
+			if (IS_ERR(inode)) {
+				parent = ERR_CAST(inode);
+			} else {
+				parent = d_obtain_alias(inode);
+				if (!IS_ERR(parent)) {
+					parent = ERR_PTR(-ENOMEM);
+					iput(inode);
+				}
+			}
+		}
+	}
+	return parent;
+}
+
+/* Just declare a zero structure as a NULL value implies
+ * using the default functions of exportfs.
+ */
+
+static struct export_operations yaffs_export_ops = {
+	.fh_to_dentry = yaffs2_fh_to_dentry,
+	.fh_to_parent = yaffs2_fh_to_parent,
+	.get_parent = yaffs2_get_parent,
+};
+
+
+/*-----------------------------------------------------------------*/
+
+static int yaffs_readlink(struct dentry *dentry, char __user * buffer,
+			  int buflen)
+{
+	unsigned char *alias;
+	int ret;
+	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
+
+	yaffs_gross_unlock(dev);
+
+	if (!alias)
+		return -ENOMEM;
+
+	ret = vfs_readlink(dentry, buffer, buflen, alias);
+	kfree(alias);
+	return ret;
+}
+
+static void *yaffs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	unsigned char *alias;
+	void *ret;
+	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
+	yaffs_gross_unlock(dev);
+
+	if (!alias) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	nd_set_link(nd, alias);
+	ret = (void *)alias;
+out:
+	return ret;
+}
+
+void yaffs_put_link(struct dentry *dentry, struct nameidata *nd, void *alias)
+{
+	kfree(alias);
+}
+
+
+static void yaffs_unstitch_obj(struct inode *inode, struct yaffs_obj *obj)
+{
+	/* Clear the association between the inode and
+	 * the struct yaffs_obj.
+	 */
+	obj->my_inode = NULL;
+	yaffs_inode_to_obj_lv(inode) = NULL;
+
+	/* If the object freeing was deferred, then the real
+	 * free happens now.
+	 * This should fix the inode inconsistency problem.
+	 */
+	yaffs_handle_defered_free(obj);
+}
+
+/* yaffs_evict_inode combines into one operation what was previously done in
+ * yaffs_clear_inode() and yaffs_delete_inode()
+ *
+ */
+static void yaffs_evict_inode(struct inode *inode)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	int deleteme = 0;
+
+	obj = yaffs_inode_to_obj(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_evict_inode: ino %d, count %d %s",
+		(int)inode->i_ino,
+		atomic_read(&inode->i_count),
+		obj ? "object exists" : "null object");
+
+	if (!inode->i_nlink && !is_bad_inode(inode))
+		deleteme = 1;
+	truncate_inode_pages(&inode->i_data, 0);
+	end_writeback(inode);
+
+	if (deleteme && obj) {
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		yaffs_del_obj(obj);
+		yaffs_gross_unlock(dev);
+	}
+	if (obj) {
+		dev = obj->my_dev;
+		yaffs_gross_lock(dev);
+		yaffs_unstitch_obj(inode, obj);
+		yaffs_gross_unlock(dev);
+	}
+
+}
+
+static void yaffs_touch_super(struct yaffs_dev *dev)
+{
+	struct super_block *sb = yaffs_dev_to_lc(dev)->super;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_touch_super() sb = %p", sb);
+	if (sb)
+		sb->s_dirt = 1;
+}
+
+static int yaffs_readpage_nolock(struct file *f, struct page *pg)
+{
+	/* Lifted from jffs2 */
+
+	struct yaffs_obj *obj;
+	unsigned char *pg_buf;
+	int ret;
+	struct yaffs_dev *dev;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_readpage_nolock at %08x, size %08x",
+		(unsigned)(pg->index << PAGE_CACHE_SHIFT),
+		(unsigned)PAGE_CACHE_SIZE);
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	dev = obj->my_dev;
+
+	BUG_ON(!PageLocked(pg));
+
+	pg_buf = kmap(pg);
+	/* FIXME: Can kmap fail? */
+
+	yaffs_gross_lock(dev);
+
+	ret = yaffs_file_rd(obj, pg_buf,
+			    pg->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE);
+
+	yaffs_gross_unlock(dev);
+
+	if (ret >= 0)
+		ret = 0;
+
+	if (ret) {
+		ClearPageUptodate(pg);
+		SetPageError(pg);
+	} else {
+		SetPageUptodate(pg);
+		ClearPageError(pg);
+	}
+
+	flush_dcache_page(pg);
+	kunmap(pg);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage_nolock done");
+	return ret;
+}
+
+static int yaffs_readpage_unlock(struct file *f, struct page *pg)
+{
+	int ret = yaffs_readpage_nolock(f, pg);
+
+	unlock_page(pg);
+	return ret;
+}
+
+static int yaffs_readpage(struct file *f, struct page *pg)
+{
+	int ret;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage");
+	ret = yaffs_readpage_unlock(f, pg);
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage done");
+	return ret;
+}
+
+/* writepage inspired by/stolen from smbfs */
+
+static int yaffs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct yaffs_dev *dev;
+	struct address_space *mapping = page->mapping;
+	struct inode *inode;
+	unsigned long end_index;
+	char *buffer;
+	struct yaffs_obj *obj;
+	int n_written = 0;
+	unsigned n_bytes;
+	loff_t i_size;
+
+	if (!mapping)
+		BUG();
+	inode = mapping->host;
+	if (!inode)
+		BUG();
+	i_size = i_size_read(inode);
+
+	end_index = i_size >> PAGE_CACHE_SHIFT;
+
+	if (page->index < end_index)
+		n_bytes = PAGE_CACHE_SIZE;
+	else {
+		n_bytes = i_size & (PAGE_CACHE_SIZE - 1);
+
+		if (page->index > end_index || !n_bytes) {
+			yaffs_trace(YAFFS_TRACE_OS,
+				"yaffs_writepage at %08x, inode size = %08x!!!",
+				(unsigned)(page->index << PAGE_CACHE_SHIFT),
+				(unsigned)inode->i_size);
+			yaffs_trace(YAFFS_TRACE_OS,
+			  "                -> don't care!!");
+
+			zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+			set_page_writeback(page);
+			unlock_page(page);
+			end_page_writeback(page);
+			return 0;
+		}
+	}
+
+	if (n_bytes != PAGE_CACHE_SIZE)
+		zero_user_segment(page, n_bytes, PAGE_CACHE_SIZE);
+
+	get_page(page);
+
+	buffer = kmap(page);
+
+	obj = yaffs_inode_to_obj(inode);
+	dev = obj->my_dev;
+	yaffs_gross_lock(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_writepage at %08x, size %08x",
+		(unsigned)(page->index << PAGE_CACHE_SHIFT), n_bytes);
+	yaffs_trace(YAFFS_TRACE_OS,
+		"writepag0: obj = %05x, ino = %05x",
+		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
+
+	n_written = yaffs_wr_file(obj, buffer,
+				  page->index << PAGE_CACHE_SHIFT, n_bytes, 0);
+
+	yaffs_touch_super(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"writepag1: obj = %05x, ino = %05x",
+		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
+
+	yaffs_gross_unlock(dev);
+
+	kunmap(page);
+	set_page_writeback(page);
+	unlock_page(page);
+	end_page_writeback(page);
+	put_page(page);
+
+	return (n_written == n_bytes) ? 0 : -ENOSPC;
+}
+
+/* Space holding and freeing is done to ensure we have space available for
+ * write_begin/end.
+ * For now we just assume few parallel writes and check against a small
+ * number.
+ * Todo: need to do this with a counter to handle parallel reads better
+ */
+
+static ssize_t yaffs_hold_space(struct file *f)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+	int n_free_chunks;
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	n_free_chunks = yaffs_get_n_free_chunks(dev);
+
+	yaffs_gross_unlock(dev);
+
+	return (n_free_chunks > 20) ? 1 : 0;
+}
+
+static void yaffs_release_space(struct file *f)
+{
+	struct yaffs_obj *obj;
+	struct yaffs_dev *dev;
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	yaffs_gross_unlock(dev);
+}
+
+static int yaffs_write_begin(struct file *filp, struct address_space *mapping,
+			     loff_t pos, unsigned len, unsigned flags,
+			     struct page **pagep, void **fsdata)
+{
+	struct page *pg = NULL;
+	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+	int ret = 0;
+	int space_held = 0;
+
+	/* Get a page */
+	pg = grab_cache_page_write_begin(mapping, index, flags);
+
+	*pagep = pg;
+	if (!pg) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	yaffs_trace(YAFFS_TRACE_OS,
+		"start yaffs_write_begin index %d(%x) uptodate %d",
+		(int)index, (int)index, PageUptodate(pg) ? 1 : 0);
+
+	/* Get fs space */
+	space_held = yaffs_hold_space(filp);
+
+	if (!space_held) {
+		ret = -ENOSPC;
+		goto out;
+	}
+
+	/* Update page if required */
+
+	if (!PageUptodate(pg))
+		ret = yaffs_readpage_nolock(filp, pg);
+
+	if (ret)
+		goto out;
+
+	/* Happy path return */
+	yaffs_trace(YAFFS_TRACE_OS, "end yaffs_write_begin - ok");
+
+	return 0;
+
+out:
+	yaffs_trace(YAFFS_TRACE_OS,
+		"end yaffs_write_begin fail returning %d", ret);
+	if (space_held)
+		yaffs_release_space(filp);
+	if (pg) {
+		unlock_page(pg);
+		page_cache_release(pg);
+	}
+	return ret;
+}
+
+static ssize_t yaffs_file_write(struct file *f, const char *buf, size_t n,
+				loff_t *pos)
+{
+	struct yaffs_obj *obj;
+	int n_written, ipos;
+	struct inode *inode;
+	struct yaffs_dev *dev;
+
+	obj = yaffs_dentry_to_obj(f->f_dentry);
+
+	if (!obj) {
+		/* This should not happen */
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_file_write: hey obj is null!");
+		return -EINVAL;
+	}
+
+	dev = obj->my_dev;
+
+	yaffs_gross_lock(dev);
+
+	inode = f->f_dentry->d_inode;
+
+	if (!S_ISBLK(inode->i_mode) && f->f_flags & O_APPEND)
+		ipos = inode->i_size;
+	else
+		ipos = *pos;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_file_write about to write writing %u(%x) bytes to object %d at %d(%x)",
+		(unsigned)n, (unsigned)n, obj->obj_id, ipos, ipos);
+
+	n_written = yaffs_wr_file(obj, buf, ipos, n, 0);
+
+	yaffs_touch_super(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_file_write: %d(%x) bytes written",
+		(unsigned)n, (unsigned)n);
+
+	if (n_written > 0) {
+		ipos += n_written;
+		*pos = ipos;
+		if (ipos > inode->i_size) {
+			inode->i_size = ipos;
+			inode->i_blocks = (ipos + 511) >> 9;
+
+			yaffs_trace(YAFFS_TRACE_OS,
+				"yaffs_file_write size updated to %d bytes, %d blocks",
+				ipos, (int)(inode->i_blocks));
+		}
+	}
+	yaffs_gross_unlock(dev);
+	return (n_written == 0) && (n > 0) ? -ENOSPC : n_written;
+}
+
+static int yaffs_write_end(struct file *filp, struct address_space *mapping,
+			   loff_t pos, unsigned len, unsigned copied,
+			   struct page *pg, void *fsdadata)
+{
+	int ret = 0;
+	void *addr, *kva;
+	uint32_t offset_into_page = pos & (PAGE_CACHE_SIZE - 1);
+
+	kva = kmap(pg);
+	addr = kva + offset_into_page;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_write_end addr %p pos %x n_bytes %d",
+		addr, (unsigned)pos, copied);
+
+	ret = yaffs_file_write(filp, addr, copied, &pos);
+
+	if (ret != copied) {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_write_end not same size ret %d  copied %d",
+			ret, copied);
+		SetPageError(pg);
+	}
+
+	kunmap(pg);
+
+	yaffs_release_space(filp);
+	unlock_page(pg);
+	page_cache_release(pg);
+	return ret;
+}
+
+static int yaffs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
+	struct super_block *sb = dentry->d_sb;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_statfs");
+
+	yaffs_gross_lock(dev);
+
+	buf->f_type = YAFFS_MAGIC;
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_namelen = 255;
+
+	if (dev->data_bytes_per_chunk & (dev->data_bytes_per_chunk - 1)) {
+		/* Do this if chunk size is not a power of 2 */
+
+		uint64_t bytes_in_dev;
+		uint64_t bytes_free;
+
+		bytes_in_dev =
+		    ((uint64_t)
+		     ((dev->param.end_block - dev->param.start_block + 1))) *
+		     ((uint64_t) (dev->param.chunks_per_block *
+					   dev->data_bytes_per_chunk));
+
+		do_div(bytes_in_dev, sb->s_blocksize);
+			/* bytes_in_dev becomes the number of blocks */
+		buf->f_blocks = bytes_in_dev;
+
+		bytes_free = ((uint64_t) (yaffs_get_n_free_chunks(dev))) *
+		    ((uint64_t) (dev->data_bytes_per_chunk));
+
+		do_div(bytes_free, sb->s_blocksize);
+
+		buf->f_bfree = bytes_free;
+
+	} else if (sb->s_blocksize > dev->data_bytes_per_chunk) {
+
+		buf->f_blocks =
+		    (dev->param.end_block - dev->param.start_block + 1) *
+		    dev->param.chunks_per_block /
+		    (sb->s_blocksize / dev->data_bytes_per_chunk);
+		buf->f_bfree =
+		    yaffs_get_n_free_chunks(dev) /
+		    (sb->s_blocksize / dev->data_bytes_per_chunk);
+	} else {
+		buf->f_blocks =
+		    (dev->param.end_block - dev->param.start_block + 1) *
+		    dev->param.chunks_per_block *
+		    (dev->data_bytes_per_chunk / sb->s_blocksize);
+
+		buf->f_bfree =
+		    yaffs_get_n_free_chunks(dev) *
+		    (dev->data_bytes_per_chunk / sb->s_blocksize);
+	}
+
+	buf->f_files = 0;
+	buf->f_ffree = 0;
+	buf->f_bavail = buf->f_bfree;
+
+	yaffs_gross_unlock(dev);
+	return 0;
+}
+
+static void yaffs_flush_inodes(struct super_block *sb)
+{
+	struct inode *iptr;
+	struct yaffs_obj *obj;
+
+	list_for_each_entry(iptr, &sb->s_inodes, i_sb_list) {
+		obj = yaffs_inode_to_obj(iptr);
+		if (obj) {
+			yaffs_trace(YAFFS_TRACE_OS,
+				"flushing obj %d", obj->obj_id);
+			yaffs_flush_file(obj, 1, 0);
+		}
+	}
+}
+
+static void yaffs_flush_super(struct super_block *sb, int do_checkpoint)
+{
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+
+	if (!dev)
+		return;
+
+	yaffs_flush_inodes(sb);
+	yaffs_update_dirty_dirs(dev);
+	yaffs_flush_whole_cache(dev);
+	if (do_checkpoint)
+		yaffs_checkpoint_save(dev);
+}
+
+static unsigned yaffs_bg_gc_urgency(struct yaffs_dev *dev)
+{
+	unsigned erased_chunks =
+	    dev->n_erased_blocks * dev->param.chunks_per_block;
+	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
+	unsigned scattered = 0;	/* Free chunks not in an erased block */
+
+	if (erased_chunks < dev->n_free_chunks)
+		scattered = (dev->n_free_chunks - erased_chunks);
+
+	if (!context->bg_running)
+		return 0;
+	else if (scattered < (dev->param.chunks_per_block * 2))
+		return 0;
+	else if (erased_chunks > dev->n_free_chunks / 2)
+		return 0;
+	else if (erased_chunks > dev->n_free_chunks / 4)
+		return 1;
+	else
+		return 2;
+}
+
+static int yaffs_do_sync_fs(struct super_block *sb, int request_checkpoint)
+{
+
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+	unsigned int oneshot_checkpoint = (yaffs_auto_checkpoint & 4);
+	unsigned gc_urgent = yaffs_bg_gc_urgency(dev);
+	int do_checkpoint;
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
+		"yaffs_do_sync_fs: gc-urgency %d %s %s%s",
+		gc_urgent,
+		sb->s_dirt ? "dirty" : "clean",
+		request_checkpoint ? "checkpoint requested" : "no checkpoint",
+		oneshot_checkpoint ? " one-shot" : "");
+
+	yaffs_gross_lock(dev);
+	do_checkpoint = ((request_checkpoint && !gc_urgent) ||
+			 oneshot_checkpoint) && !dev->is_checkpointed;
+
+	if (sb->s_dirt || do_checkpoint) {
+		yaffs_flush_super(sb, !dev->is_checkpointed && do_checkpoint);
+		sb->s_dirt = 0;
+		if (oneshot_checkpoint)
+			yaffs_auto_checkpoint &= ~4;
+	}
+	yaffs_gross_unlock(dev);
+
+	return 0;
+}
+
+/*
+ * yaffs background thread functions .
+ * yaffs_bg_thread_fn() the thread function
+ * yaffs_bg_start() launches the background thread.
+ * yaffs_bg_stop() cleans up the background thread.
+ *
+ * NB:
+ * The thread should only run after the yaffs is initialised
+ * The thread should be stopped before yaffs is unmounted.
+ * The thread should not do any writing while the fs is in read only.
+ */
+
+void yaffs_background_waker(unsigned long data)
+{
+	wake_up_process((struct task_struct *)data);
+}
+
+static int yaffs_bg_thread_fn(void *data)
+{
+	struct yaffs_dev *dev = (struct yaffs_dev *)data;
+	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
+	unsigned long now = jiffies;
+	unsigned long next_dir_update = now;
+	unsigned long next_gc = now;
+	unsigned long expires;
+	unsigned int urgency;
+	int gc_result;
+	struct timer_list timer;
+
+	yaffs_trace(YAFFS_TRACE_BACKGROUND,
+		"yaffs_background starting for dev %p", (void *)dev);
+
+	set_freezable();
+	while (context->bg_running) {
+		yaffs_trace(YAFFS_TRACE_BACKGROUND, "yaffs_background");
+
+		if (kthread_should_stop())
+			break;
+
+		if (try_to_freeze())
+			continue;
+
+		yaffs_gross_lock(dev);
+
+		now = jiffies;
+
+		if (time_after(now, next_dir_update) && yaffs_bg_enable) {
+			yaffs_update_dirty_dirs(dev);
+			next_dir_update = now + HZ;
+		}
+
+		if (time_after(now, next_gc) && yaffs_bg_enable) {
+			if (!dev->is_checkpointed) {
+				urgency = yaffs_bg_gc_urgency(dev);
+				gc_result = yaffs_bg_gc(dev, urgency);
+				if (urgency > 1)
+					next_gc = now + HZ / 20 + 1;
+				else if (urgency > 0)
+					next_gc = now + HZ / 10 + 1;
+				else
+					next_gc = now + HZ * 2;
+			} else	{
+				/*
+				 * gc not running so set to next_dir_update
+				 * to cut down on wake ups
+				 */
+				next_gc = next_dir_update;
+			}
+		}
+		yaffs_gross_unlock(dev);
+		expires = next_dir_update;
+		if (time_before(next_gc, expires))
+			expires = next_gc;
+		if (time_before(expires, now))
+			expires = now + HZ;
+
+		init_timer_on_stack(&timer);
+		timer.expires = expires + 1;
+		timer.data = (unsigned long)current;
+		timer.function = yaffs_background_waker;
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		add_timer(&timer);
+		schedule();
+		del_timer_sync(&timer);
+	}
+
+	return 0;
+}
+
+static int yaffs_bg_start(struct yaffs_dev *dev)
+{
+	int retval = 0;
+	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
+
+	if (dev->read_only)
+		return -1;
+
+	context->bg_running = 1;
+
+	context->bg_thread = kthread_run(yaffs_bg_thread_fn,
+					 (void *)dev, "yaffs-bg-%d",
+					 context->mount_id);
+
+	if (IS_ERR(context->bg_thread)) {
+		retval = PTR_ERR(context->bg_thread);
+		context->bg_thread = NULL;
+		context->bg_running = 0;
+	}
+	return retval;
+}
+
+static void yaffs_bg_stop(struct yaffs_dev *dev)
+{
+	struct yaffs_linux_context *ctxt = yaffs_dev_to_lc(dev);
+
+	ctxt->bg_running = 0;
+
+	if (ctxt->bg_thread) {
+		kthread_stop(ctxt->bg_thread);
+		ctxt->bg_thread = NULL;
+	}
+}
+
+static void yaffs_write_super(struct super_block *sb)
+{
+	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 2);
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
+		"yaffs_write_super%s",
+		request_checkpoint ? " checkpt" : "");
+
+	yaffs_do_sync_fs(sb, request_checkpoint);
+
+}
+
+static int yaffs_sync_fs(struct super_block *sb, int wait)
+{
+	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 1);
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC,
+		"yaffs_sync_fs%s", request_checkpoint ? " checkpt" : "");
+
+	yaffs_do_sync_fs(sb, request_checkpoint);
+
+	return 0;
+}
+
+static LIST_HEAD(yaffs_context_list);
+struct mutex yaffs_context_lock;
+
+struct yaffs_options {
+	int inband_tags;
+	int skip_checkpoint_read;
+	int skip_checkpoint_write;
+	int no_cache;
+	int tags_ecc_on;
+	int tags_ecc_overridden;
+	int lazy_loading_enabled;
+	int lazy_loading_overridden;
+	int empty_lost_and_found;
+	int empty_lost_and_found_overridden;
+};
+
+#define MAX_OPT_LEN 30
+static int yaffs_parse_options(struct yaffs_options *options,
+				const char *options_str)
+{
+	char cur_opt[MAX_OPT_LEN + 1];
+	int p;
+	int error = 0;
+
+	/* Parse through the options which is a comma seperated list */
+
+	while (options_str && *options_str && !error) {
+		memset(cur_opt, 0, MAX_OPT_LEN + 1);
+		p = 0;
+
+		while (*options_str == ',')
+			options_str++;
+
+		while (*options_str && *options_str != ',') {
+			if (p < MAX_OPT_LEN) {
+				cur_opt[p] = *options_str;
+				p++;
+			}
+			options_str++;
+		}
+
+		if (!strcmp(cur_opt, "inband-tags")) {
+			options->inband_tags = 1;
+		} else if (!strcmp(cur_opt, "tags-ecc-off")) {
+			options->tags_ecc_on = 0;
+			options->tags_ecc_overridden = 1;
+		} else if (!strcmp(cur_opt, "tags-ecc-on")) {
+			options->tags_ecc_on = 1;
+			options->tags_ecc_overridden = 1;
+		} else if (!strcmp(cur_opt, "lazy-loading-off")) {
+			options->lazy_loading_enabled = 0;
+			options->lazy_loading_overridden = 1;
+		} else if (!strcmp(cur_opt, "lazy-loading-on")) {
+			options->lazy_loading_enabled = 1;
+			options->lazy_loading_overridden = 1;
+		} else if (!strcmp(cur_opt, "empty-lost-and-found-off")) {
+			options->empty_lost_and_found = 0;
+			options->empty_lost_and_found_overridden = 1;
+		} else if (!strcmp(cur_opt, "empty-lost-and-found-on")) {
+			options->empty_lost_and_found = 1;
+			options->empty_lost_and_found_overridden = 1;
+		} else if (!strcmp(cur_opt, "no-cache")) {
+			options->no_cache = 1;
+		} else if (!strcmp(cur_opt, "no-checkpoint-read")) {
+			options->skip_checkpoint_read = 1;
+		} else if (!strcmp(cur_opt, "no-checkpoint-write")) {
+			options->skip_checkpoint_write = 1;
+		} else if (!strcmp(cur_opt, "no-checkpoint")) {
+			options->skip_checkpoint_read = 1;
+			options->skip_checkpoint_write = 1;
+		} else {
+			printk(KERN_INFO "yaffs: Bad mount option \"%s\"\n",
+			       cur_opt);
+			error = 1;
+		}
+	}
+	return error;
+}
+
+static const struct address_space_operations yaffs_file_address_operations = {
+	.readpage = yaffs_readpage,
+	.writepage = yaffs_writepage,
+	.write_begin = yaffs_write_begin,
+	.write_end = yaffs_write_end,
+};
+
+
+
+static const struct inode_operations yaffs_file_inode_operations = {
+	.setattr = yaffs_setattr,
+#ifdef CONFIG_YAFFS_XATTR
+	.setxattr = yaffs_setxattr,
+	.getxattr = yaffs_getxattr,
+	.listxattr = yaffs_listxattr,
+	.removexattr = yaffs_removexattr,
+#endif
+};
+
+static const struct inode_operations yaffs_symlink_inode_operations = {
+	.readlink = yaffs_readlink,
+	.follow_link = yaffs_follow_link,
+	.put_link = yaffs_put_link,
+	.setattr = yaffs_setattr,
+#ifdef CONFIG_YAFFS_XATTR
+	.setxattr = yaffs_setxattr,
+	.getxattr = yaffs_getxattr,
+	.listxattr = yaffs_listxattr,
+	.removexattr = yaffs_removexattr,
+#endif
+};
+
+static void yaffs_fill_inode_from_obj(struct inode *inode,
+				      struct yaffs_obj *obj)
+{
+	u32 mode;
+
+	if (!inode || !obj)  {
+		yaffs_trace(YAFFS_TRACE_OS,
+			"yaffs_fill_inode invalid parameters");
+		return;
+	}
+
+	/* Check mode against the variant type
+	 * and attempt to repair if broken. */
+	mode = obj->yst_mode;
+
+	switch (obj->variant_type) {
+	case YAFFS_OBJECT_TYPE_FILE:
+		if (!S_ISREG(mode)) {
+			obj->yst_mode &= ~S_IFMT;
+			obj->yst_mode |= S_IFREG;
+		}
+		break;
+	case YAFFS_OBJECT_TYPE_SYMLINK:
+		if (!S_ISLNK(mode)) {
+			obj->yst_mode &= ~S_IFMT;
+			obj->yst_mode |= S_IFLNK;
+		}
+		break;
+	case YAFFS_OBJECT_TYPE_DIRECTORY:
+		if (!S_ISDIR(mode)) {
+			obj->yst_mode &= ~S_IFMT;
+			obj->yst_mode |= S_IFDIR;
+		}
+		break;
+	case YAFFS_OBJECT_TYPE_UNKNOWN:
+	case YAFFS_OBJECT_TYPE_HARDLINK:
+	case YAFFS_OBJECT_TYPE_SPECIAL:
+	default:
+		/* TODO? */
+		break;
+	}
+
+	inode->i_flags |= S_NOATIME;
+	inode->i_ino = obj->obj_id;
+	inode->i_mode = obj->yst_mode;
+	inode->i_uid = obj->yst_uid;
+	inode->i_gid = obj->yst_gid;
+
+	inode->i_rdev = old_decode_dev(obj->yst_rdev);
+
+	inode->i_atime.tv_sec = (time_t) (obj->yst_atime);
+	inode->i_atime.tv_nsec = 0;
+	inode->i_mtime.tv_sec = (time_t) obj->yst_mtime;
+	inode->i_mtime.tv_nsec = 0;
+	inode->i_ctime.tv_sec = (time_t) obj->yst_ctime;
+	inode->i_ctime.tv_nsec = 0;
+	inode->i_size = yaffs_get_obj_length(obj);
+	inode->i_blocks = (inode->i_size + 511) >> 9;
+	inode->i_nlink = yaffs_get_obj_link_count(obj);
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_fill_inode mode %x uid %d gid %d size %d count %d",
+		inode->i_mode, inode->i_uid, inode->i_gid,
+		(int)inode->i_size, atomic_read(&inode->i_count));
+
+	switch (obj->yst_mode & S_IFMT) {
+	default:	/* fifo, device or socket */
+		init_special_inode(inode, obj->yst_mode,
+				   old_decode_dev(obj->yst_rdev));
+		break;
+	case S_IFREG:	/* file */
+		inode->i_op = &yaffs_file_inode_operations;
+		inode->i_fop = &yaffs_file_operations;
+		inode->i_mapping->a_ops = &yaffs_file_address_operations;
+		break;
+	case S_IFDIR:	/* directory */
+		inode->i_op = &yaffs_dir_inode_operations;
+		inode->i_fop = &yaffs_dir_operations;
+		break;
+	case S_IFLNK:	/* symlink */
+		inode->i_op = &yaffs_symlink_inode_operations;
+		break;
+	}
+
+	yaffs_inode_to_obj_lv(inode) = obj;
+	obj->my_inode = inode;
+}
+
+static void yaffs_put_super(struct super_block *sb)
+{
+	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_put_super");
+
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
+		"Shutting down yaffs background thread");
+	yaffs_bg_stop(dev);
+	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
+		"yaffs background thread shut down");
+
+	yaffs_gross_lock(dev);
+
+	yaffs_flush_super(sb, 1);
+
+	if (yaffs_dev_to_lc(dev)->put_super_fn)
+		yaffs_dev_to_lc(dev)->put_super_fn(sb);
+
+	yaffs_deinitialise(dev);
+
+	yaffs_gross_unlock(dev);
+	mutex_lock(&yaffs_context_lock);
+	list_del_init(&(yaffs_dev_to_lc(dev)->context_list));
+	mutex_unlock(&yaffs_context_lock);
+
+	if (yaffs_dev_to_lc(dev)->spare_buffer) {
+		kfree(yaffs_dev_to_lc(dev)->spare_buffer);
+		yaffs_dev_to_lc(dev)->spare_buffer = NULL;
+	}
+
+	kfree(dev);
+}
+
+static void yaffs_mtd_put_super(struct super_block *sb)
+{
+	struct mtd_info *mtd = yaffs_dev_to_mtd(yaffs_super_to_dev(sb));
+
+	if (mtd->sync)
+		mtd->sync(mtd);
+
+	put_mtd_device(mtd);
+}
+
+static const struct super_operations yaffs_super_ops = {
+	.statfs = yaffs_statfs,
+	.put_super = yaffs_put_super,
+	.evict_inode = yaffs_evict_inode,
+	.sync_fs = yaffs_sync_fs,
+	.write_super = yaffs_write_super,
+};
+
+static struct super_block *yaffs_internal_read_super(int yaffs_version,
+						     struct super_block *sb,
+						     void *data, int silent)
+{
+	int n_blocks;
+	struct inode *inode = NULL;
+	struct dentry *root;
+	struct yaffs_dev *dev = 0;
+	char devname_buf[BDEVNAME_SIZE + 1];
+	struct mtd_info *mtd;
+	int err;
+	char *data_str = (char *)data;
+	struct yaffs_linux_context *context = NULL;
+	struct yaffs_param *param;
+	int read_only = 0;
+	struct yaffs_options options;
+	unsigned mount_id;
+	int found;
+	struct yaffs_linux_context *context_iterator;
+	struct list_head *l;
+
+	if (!sb) {
+		printk(KERN_INFO "yaffs: sb is NULL\n");
+		return NULL;
+	}
+
+	sb->s_magic = YAFFS_MAGIC;
+	sb->s_op = &yaffs_super_ops;
+	sb->s_flags |= MS_NOATIME;
+
+	read_only = ((sb->s_flags & MS_RDONLY) != 0);
+
+	sb->s_export_op = &yaffs_export_ops;
+
+	if (!sb->s_dev)
+		printk(KERN_INFO "yaffs: sb->s_dev is NULL\n");
+	else if (!yaffs_devname(sb, devname_buf))
+		printk(KERN_INFO "yaffs: devname is NULL\n");
+	else
+		printk(KERN_INFO "yaffs: dev is %d name is \"%s\" %s\n",
+		       sb->s_dev,
+		       yaffs_devname(sb, devname_buf), read_only ? "ro" : "rw");
+
+	if (!data_str)
+		data_str = "";
+
+	printk(KERN_INFO "yaffs: passed flags \"%s\"\n", data_str);
+
+	memset(&options, 0, sizeof(options));
+
+	if (yaffs_parse_options(&options, data_str))
+		/* Option parsing failed */
+		return NULL;
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_read_super: Using yaffs%d", yaffs_version);
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_read_super: block size %d", (int)(sb->s_blocksize));
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"Attempting MTD mount of %u.%u,\"%s\"",
+		MAJOR(sb->s_dev), MINOR(sb->s_dev),
+		yaffs_devname(sb, devname_buf));
+
+	/* Check it's an mtd device..... */
+	if (MAJOR(sb->s_dev) != MTD_BLOCK_MAJOR)
+		return NULL;	/* This isn't an mtd device */
+
+	/* Get the device */
+	mtd = get_mtd_device(NULL, MINOR(sb->s_dev));
+	if (!mtd) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"MTD device #%u doesn't appear to exist",
+			MINOR(sb->s_dev));
+		return NULL;
+	}
+	/* Check it's NAND */
+	if (mtd->type != MTD_NANDFLASH) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"MTD device is not NAND it's type %d",
+			mtd->type);
+		return NULL;
+	}
+
+	yaffs_trace(YAFFS_TRACE_OS, " erase %p", mtd->erase);
+	yaffs_trace(YAFFS_TRACE_OS, " read %p", mtd->read);
+	yaffs_trace(YAFFS_TRACE_OS, " write %p", mtd->write);
+	yaffs_trace(YAFFS_TRACE_OS, " readoob %p", mtd->read_oob);
+	yaffs_trace(YAFFS_TRACE_OS, " writeoob %p", mtd->write_oob);
+	yaffs_trace(YAFFS_TRACE_OS, " block_isbad %p", mtd->block_isbad);
+	yaffs_trace(YAFFS_TRACE_OS, " block_markbad %p", mtd->block_markbad);
+	yaffs_trace(YAFFS_TRACE_OS, " writesize %d", mtd->writesize);
+	yaffs_trace(YAFFS_TRACE_OS, " oobsize %d", mtd->oobsize);
+	yaffs_trace(YAFFS_TRACE_OS, " erasesize %d", mtd->erasesize);
+	yaffs_trace(YAFFS_TRACE_OS, " size %lld", mtd->size);
+
+#ifdef CONFIG_YAFFS_AUTO_YAFFS2
+
+	if (yaffs_version == 1 && mtd->writesize >= 2048) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs2");
+		yaffs_version = 2;
+	}
+
+	/* Added NCB 26/5/2006 for completeness */
+	if (yaffs_version == 2 && !options.inband_tags &&
+		mtd->writesize == 512) {
+		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs1");
+		yaffs_version = 1;
+	}
+#endif
+
+	if (yaffs_version == 2) {
+		/* Check for version 2 style functions */
+		if (!mtd->erase ||
+		    !mtd->block_isbad ||
+		    !mtd->block_markbad ||
+		    !mtd->read ||
+		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not support required functions");
+			return NULL;
+		}
+
+		if ((mtd->writesize < YAFFS_MIN_YAFFS2_CHUNK_SIZE ||
+		     mtd->oobsize < YAFFS_MIN_YAFFS2_SPARE_SIZE) &&
+		    !options.inband_tags) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not have the right page sizes");
+			return NULL;
+		}
+	} else {
+		/* Check for V1 style functions */
+		if (!mtd->erase ||
+		    !mtd->read ||
+		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not support required functions");
+			return NULL;
+		}
+
+		if (mtd->writesize < YAFFS_BYTES_PER_CHUNK ||
+		    mtd->oobsize != YAFFS_BYTES_PER_SPARE) {
+			yaffs_trace(YAFFS_TRACE_ALWAYS,
+				"MTD device does not support have the right page sizes");
+			return NULL;
+		}
+	}
+
+	/* OK, so if we got here, we have an MTD that's NAND and looks
+	 * like it has the right capabilities
+	 * Set the struct yaffs_dev up for mtd
+	 */
+
+	if (!read_only && !(mtd->flags & MTD_WRITEABLE)) {
+		read_only = 1;
+		printk(KERN_INFO
+		       "yaffs: mtd is read only, setting superblock read only");
+		sb->s_flags |= MS_RDONLY;
+	}
+
+	dev = kmalloc(sizeof(struct yaffs_dev), GFP_KERNEL);
+	context = kmalloc(sizeof(struct yaffs_linux_context), GFP_KERNEL);
+
+	if (!dev || !context) {
+		kfree(dev);
+		kfree(context);
+		dev = NULL;
+		context = NULL;
+	}
+
+	if (!dev) {
+		/* Deep shit could not allocate device structure */
+		yaffs_trace(YAFFS_TRACE_ALWAYS,
+			"yaffs_read_super failed trying to allocate yaffs_dev");
+		return NULL;
+	}
+	memset(dev, 0, sizeof(struct yaffs_dev));
+	param = &(dev->param);
+
+	memset(context, 0, sizeof(struct yaffs_linux_context));
+	dev->os_context = context;
+	INIT_LIST_HEAD(&(context->context_list));
+	context->dev = dev;
+	context->super = sb;
+
+	dev->read_only = read_only;
+
+	sb->s_fs_info = dev;
+
+	dev->driver_context = mtd;
+	param->name = mtd->name;
+
+	/* Set up the memory size parameters.... */
+
+	n_blocks =
+	    YCALCBLOCKS(mtd->size,
+			(YAFFS_CHUNKS_PER_BLOCK * YAFFS_BYTES_PER_CHUNK));
+
+	param->start_block = 0;
+	param->end_block = n_blocks - 1;
+	param->chunks_per_block = YAFFS_CHUNKS_PER_BLOCK;
+	param->total_bytes_per_chunk = YAFFS_BYTES_PER_CHUNK;
+	param->n_reserved_blocks = 5;
+	param->n_caches = (options.no_cache) ? 0 : 10;
+	param->inband_tags = options.inband_tags;
+
+#ifdef CONFIG_YAFFS_DISABLE_LAZY_LOAD
+	param->disable_lazy_load = 1;
+#endif
+#ifdef CONFIG_YAFFS_XATTR
+	param->enable_xattr = 1;
+#endif
+	if (options.lazy_loading_overridden)
+		param->disable_lazy_load = !options.lazy_loading_enabled;
+
+#ifdef CONFIG_YAFFS_DISABLE_TAGS_ECC
+	param->no_tags_ecc = 1;
+#endif
+
+#ifdef CONFIG_YAFFS_DISABLE_BACKGROUND
+#else
+	param->defered_dir_update = 1;
+#endif
+
+	if (options.tags_ecc_overridden)
+		param->no_tags_ecc = !options.tags_ecc_on;
+
+#ifdef CONFIG_YAFFS_EMPTY_LOST_AND_FOUND
+	param->empty_lost_n_found = 1;
+#endif
+
+#ifdef CONFIG_YAFFS_DISABLE_BLOCK_REFRESHING
+	param->refresh_period = 0;
+#else
+	param->refresh_period = 500;
+#endif
+
+#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
+	param->always_check_erased = 1;
+#endif
+
+	if (options.empty_lost_and_found_overridden)
+		param->empty_lost_n_found = options.empty_lost_and_found;
+
+	/* ... and the functions. */
+	if (yaffs_version == 2) {
+		param->write_chunk_tags_fn = nandmtd2_write_chunk_tags;
+		param->read_chunk_tags_fn = nandmtd2_read_chunk_tags;
+		param->bad_block_fn = nandmtd2_mark_block_bad;
+		param->query_block_fn = nandmtd2_query_block;
+		yaffs_dev_to_lc(dev)->spare_buffer =
+				kmalloc(mtd->oobsize, GFP_NOFS);
+		param->is_yaffs2 = 1;
+		param->total_bytes_per_chunk = mtd->writesize;
+		param->chunks_per_block = mtd->erasesize / mtd->writesize;
+		n_blocks = YCALCBLOCKS(mtd->size, mtd->erasesize);
+
+		param->start_block = 0;
+		param->end_block = n_blocks - 1;
+	} else {
+		/* use the MTD interface in yaffs_mtdif1.c */
+		param->write_chunk_tags_fn = nandmtd1_write_chunk_tags;
+		param->read_chunk_tags_fn = nandmtd1_read_chunk_tags;
+		param->bad_block_fn = nandmtd1_mark_block_bad;
+		param->query_block_fn = nandmtd1_query_block;
+		param->is_yaffs2 = 0;
+	}
+	/* ... and common functions */
+	param->erase_fn = nandmtd_erase_block;
+	param->initialise_flash_fn = nandmtd_initialise;
+
+	yaffs_dev_to_lc(dev)->put_super_fn = yaffs_mtd_put_super;
+
+	param->sb_dirty_fn = yaffs_touch_super;
+	param->gc_control = yaffs_gc_control_callback;
+
+	yaffs_dev_to_lc(dev)->super = sb;
+
+#ifndef CONFIG_YAFFS_DOES_ECC
+	param->use_nand_ecc = 1;
+#endif
+
+	param->skip_checkpt_rd = options.skip_checkpoint_read;
+	param->skip_checkpt_wr = options.skip_checkpoint_write;
+
+	mutex_lock(&yaffs_context_lock);
+	/* Get a mount id */
+	for (mount_id = 0, found = 0; !found; mount_id++) {
+		found = 1;
+		list_for_each(l, &yaffs_context_list) {
+			context_iterator =
+				list_entry(l, struct yaffs_linux_context,
+					context_list);
+			if (context_iterator->mount_id == mount_id)
+				found = 0;
+		}
+	}
+	context->mount_id = mount_id;
+
+	list_add_tail(&(yaffs_dev_to_lc(dev)->context_list),
+		      &yaffs_context_list);
+	mutex_unlock(&yaffs_context_lock);
+
+	/* Directory search handling... */
+	INIT_LIST_HEAD(&(yaffs_dev_to_lc(dev)->search_contexts));
+	param->remove_obj_fn = yaffs_remove_obj_callback;
+
+	mutex_init(&(yaffs_dev_to_lc(dev)->gross_lock));
+
+	yaffs_gross_lock(dev);
+
+	err = yaffs_guts_initialise(dev);
+
+	yaffs_trace(YAFFS_TRACE_OS,
+		"yaffs_read_super: guts initialised %s",
+		(err == YAFFS_OK) ? "OK" : "FAILED");
+
+	if (err == YAFFS_OK)
+		yaffs_bg_start(dev);
+
+	if (!context->bg_thread)
+		param->defered_dir_update = 0;
+
+	/* Release lock before yaffs_get_inode() */
+	yaffs_gross_unlock(dev);
+
+	/* Create root inode */
+	if (err == YAFFS_OK)
+		inode = yaffs_get_inode(sb, S_IFDIR | 0755, 0, yaffs_root(dev));
+
+	if (!inode)
+		return NULL;
+
+	inode->i_op = &yaffs_dir_inode_operations;
+	inode->i_fop = &yaffs_dir_operations;
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: got root inode");
+
+	root = d_alloc_root(inode);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: d_alloc_root done");
+
+	if (!root) {
+		iput(inode);
+		return NULL;
+	}
+	sb->s_root = root;
+	sb->s_dirt = !dev->is_checkpointed;
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"yaffs_read_super: is_checkpointed %d",
+		dev->is_checkpointed);
+
+	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: done");
+	return sb;
+}
+
+static int yaffs_internal_read_super_mtd(struct super_block *sb, void *data,
+					 int silent)
+{
+	return yaffs_internal_read_super(1, sb, data, silent) ? 0 : -EINVAL;
+}
+
+static int yaffs_read_super(struct file_system_type *fs,
+			    int flags, const char *dev_name,
+			    void *data, struct vfsmount *mnt)
+{
+
+	return get_sb_bdev(fs, flags, dev_name, data,
+			   yaffs_internal_read_super_mtd, mnt);
+}
+
+static struct file_system_type yaffs_fs_type = {
+	.owner = THIS_MODULE,
+	.name = "yaffs",
+	.get_sb = yaffs_read_super,
+	.kill_sb = kill_block_super,
+	.fs_flags = FS_REQUIRES_DEV,
+};
+
+#ifdef CONFIG_YAFFS_YAFFS2
+
+static int yaffs2_internal_read_super_mtd(struct super_block *sb, void *data,
+					  int silent)
+{
+	return yaffs_internal_read_super(2, sb, data, silent) ? 0 : -EINVAL;
+}
+
+static int yaffs2_read_super(struct file_system_type *fs,
+			     int flags, const char *dev_name, void *data,
+			     struct vfsmount *mnt)
+{
+	return get_sb_bdev(fs, flags, dev_name, data,
+			   yaffs2_internal_read_super_mtd, mnt);
+}
+
+static struct file_system_type yaffs2_fs_type = {
+	.owner = THIS_MODULE,
+	.name = "yaffs2",
+	.get_sb = yaffs2_read_super,
+	.kill_sb = kill_block_super,
+	.fs_flags = FS_REQUIRES_DEV,
+};
+#endif /* CONFIG_YAFFS_YAFFS2 */
+
+static struct proc_dir_entry *my_proc_entry;
+
+static char *yaffs_dump_dev_part0(char *buf, struct yaffs_dev *dev)
+{
+	struct yaffs_param *param = &dev->param;
+
+	buf += sprintf(buf, "start_block........... %d\n", param->start_block);
+	buf += sprintf(buf, "end_block............. %d\n", param->end_block);
+	buf += sprintf(buf, "total_bytes_per_chunk. %d\n",
+			param->total_bytes_per_chunk);
+	buf += sprintf(buf, "use_nand_ecc.......... %d\n",
+			param->use_nand_ecc);
+	buf += sprintf(buf, "no_tags_ecc........... %d\n", param->no_tags_ecc);
+	buf += sprintf(buf, "is_yaffs2............. %d\n", param->is_yaffs2);
+	buf += sprintf(buf, "inband_tags........... %d\n", param->inband_tags);
+	buf += sprintf(buf, "empty_lost_n_found.... %d\n",
+			param->empty_lost_n_found);
+	buf += sprintf(buf, "disable_lazy_load..... %d\n",
+			param->disable_lazy_load);
+	buf += sprintf(buf, "refresh_period........ %d\n",
+			param->refresh_period);
+	buf += sprintf(buf, "n_caches.............. %d\n", param->n_caches);
+	buf += sprintf(buf, "n_reserved_blocks..... %d\n",
+			param->n_reserved_blocks);
+	buf += sprintf(buf, "always_check_erased... %d\n",
+			param->always_check_erased);
+
+	return buf;
+}
+
+static char *yaffs_dump_dev_part1(char *buf, struct yaffs_dev *dev)
+{
+	buf +=
+	    sprintf(buf, "data_bytes_per_chunk.. %d\n",
+		    dev->data_bytes_per_chunk);
+	buf += sprintf(buf, "chunk_grp_bits........ %d\n", dev->chunk_grp_bits);
+	buf += sprintf(buf, "chunk_grp_size........ %d\n", dev->chunk_grp_size);
+	buf +=
+	    sprintf(buf, "n_erased_blocks....... %d\n", dev->n_erased_blocks);
+	buf +=
+	    sprintf(buf, "blocks_in_checkpt..... %d\n", dev->blocks_in_checkpt);
+	buf += sprintf(buf, "\n");
+	buf += sprintf(buf, "n_tnodes.............. %d\n", dev->n_tnodes);
+	buf += sprintf(buf, "n_obj................. %d\n", dev->n_obj);
+	buf += sprintf(buf, "n_free_chunks......... %d\n", dev->n_free_chunks);
+	buf += sprintf(buf, "\n");
+	buf += sprintf(buf, "n_page_writes......... %u\n", dev->n_page_writes);
+	buf += sprintf(buf, "n_page_reads.......... %u\n", dev->n_page_reads);
+	buf += sprintf(buf, "n_erasures............ %u\n", dev->n_erasures);
+	buf += sprintf(buf, "n_gc_copies........... %u\n", dev->n_gc_copies);
+	buf += sprintf(buf, "all_gcs............... %u\n", dev->all_gcs);
+	buf +=
+	    sprintf(buf, "passive_gc_count...... %u\n", dev->passive_gc_count);
+	buf +=
+	    sprintf(buf, "oldest_dirty_gc_count. %u\n",
+		    dev->oldest_dirty_gc_count);
+	buf += sprintf(buf, "n_gc_blocks........... %u\n", dev->n_gc_blocks);
+	buf += sprintf(buf, "bg_gcs................ %u\n", dev->bg_gcs);
+	buf +=
+	    sprintf(buf, "n_retired_writes...... %u\n", dev->n_retired_writes);
+	buf +=
+	    sprintf(buf, "n_retired_blocks...... %u\n", dev->n_retired_blocks);
+	buf += sprintf(buf, "n_ecc_fixed........... %u\n", dev->n_ecc_fixed);
+	buf += sprintf(buf, "n_ecc_unfixed......... %u\n", dev->n_ecc_unfixed);
+	buf +=
+	    sprintf(buf, "n_tags_ecc_fixed...... %u\n", dev->n_tags_ecc_fixed);
+	buf +=
+	    sprintf(buf, "n_tags_ecc_unfixed.... %u\n",
+		    dev->n_tags_ecc_unfixed);
+	buf += sprintf(buf, "cache_hits............ %u\n", dev->cache_hits);
+	buf +=
+	    sprintf(buf, "n_deleted_files....... %u\n", dev->n_deleted_files);
+	buf +=
+	    sprintf(buf, "n_unlinked_files...... %u\n", dev->n_unlinked_files);
+	buf += sprintf(buf, "refresh_count......... %u\n", dev->refresh_count);
+	buf += sprintf(buf, "n_bg_deletions........ %u\n", dev->n_bg_deletions);
+
+	return buf;
+}
+
+static int yaffs_proc_read(char *page,
+			   char **start,
+			   off_t offset, int count, int *eof, void *data)
+{
+	struct list_head *item;
+	char *buf = page;
+	int step = offset;
+	int n = 0;
+
+	/* Get proc_file_read() to step 'offset' by one on each sucessive call.
+	 * We use 'offset' (*ppos) to indicate where we are in dev_list.
+	 * This also assumes the user has posted a read buffer large
+	 * enough to hold the complete output; but that's life in /proc.
+	 */
+
+	*(int *)start = 1;
+
+	/* Print header first */
+	if (step == 0)
+		buf += sprintf(buf, "YAFFS built:" __DATE__ " " __TIME__ "\n");
+	else if (step == 1)
+		buf += sprintf(buf, "\n");
+	else {
+		step -= 2;
+
+		mutex_lock(&yaffs_context_lock);
+
+		/* Locate and print the Nth entry.
+		 * Order N-squared but N is small. */
+		list_for_each(item, &yaffs_context_list) {
+			struct yaffs_linux_context *dc =
+			    list_entry(item, struct yaffs_linux_context,
+				       context_list);
+			struct yaffs_dev *dev = dc->dev;
+
+			if (n < (step & ~1)) {
+				n += 2;
+				continue;
+			}
+			if ((step & 1) == 0) {
+				buf +=
+				    sprintf(buf, "\nDevice %d \"%s\"\n", n,
+					    dev->param.name);
+				buf = yaffs_dump_dev_part0(buf, dev);
+			} else {
+				buf = yaffs_dump_dev_part1(buf, dev);
+			}
+
+			break;
+		}
+		mutex_unlock(&yaffs_context_lock);
+	}
+
+	return buf - page < count ? buf - page : count;
+}
+
+
+/**
+ * Set the verbosity of the warnings and error messages.
+ *
+ * Note that the names can only be a..z or _ with the current code.
+ */
+
+static struct {
+	char *mask_name;
+	unsigned mask_bitfield;
+} mask_flags[] = {
+	{"allocate", YAFFS_TRACE_ALLOCATE},
+	{"always", YAFFS_TRACE_ALWAYS},
+	{"background", YAFFS_TRACE_BACKGROUND},
+	{"bad_blocks", YAFFS_TRACE_BAD_BLOCKS},
+	{"buffers", YAFFS_TRACE_BUFFERS},
+	{"bug", YAFFS_TRACE_BUG},
+	{"checkpt", YAFFS_TRACE_CHECKPOINT},
+	{"deletion", YAFFS_TRACE_DELETION},
+	{"erase", YAFFS_TRACE_ERASE},
+	{"error", YAFFS_TRACE_ERROR},
+	{"gc_detail", YAFFS_TRACE_GC_DETAIL},
+	{"gc", YAFFS_TRACE_GC},
+	{"lock", YAFFS_TRACE_LOCK},
+	{"mtd", YAFFS_TRACE_MTD},
+	{"nandaccess", YAFFS_TRACE_NANDACCESS},
+	{"os", YAFFS_TRACE_OS},
+	{"scan_debug", YAFFS_TRACE_SCAN_DEBUG},
+	{"scan", YAFFS_TRACE_SCAN},
+	{"mount", YAFFS_TRACE_MOUNT},
+	{"tracing", YAFFS_TRACE_TRACING},
+	{"sync", YAFFS_TRACE_SYNC},
+	{"write", YAFFS_TRACE_WRITE},
+	{"verify", YAFFS_TRACE_VERIFY},
+	{"verify_nand", YAFFS_TRACE_VERIFY_NAND},
+	{"verify_full", YAFFS_TRACE_VERIFY_FULL},
+	{"verify_all", YAFFS_TRACE_VERIFY_ALL},
+	{"all", 0xffffffff},
+	{"none", 0},
+	{NULL, 0},
+};
+
+#define MAX_MASK_NAME_LENGTH 40
+static int yaffs_proc_write_trace_options(struct file *file, const char *buf,
+					  unsigned long count, void *data)
+{
+	unsigned rg = 0, mask_bitfield;
+	char *end;
+	char *mask_name;
+	const char *x;
+	char substring[MAX_MASK_NAME_LENGTH + 1];
+	int i;
+	int done = 0;
+	int add, len = 0;
+	int pos = 0;
+
+	rg = yaffs_trace_mask;
+
+	while (!done && (pos < count)) {
+		done = 1;
+		while ((pos < count) && isspace(buf[pos]))
+			pos++;
+
+		switch (buf[pos]) {
+		case '+':
+		case '-':
+		case '=':
+			add = buf[pos];
+			pos++;
+			break;
+
+		default:
+			add = ' ';
+			break;
+		}
+		mask_name = NULL;
+
+		mask_bitfield = simple_strtoul(buf + pos, &end, 0);
+
+		if (end > buf + pos) {
+			mask_name = "numeral";
+			len = end - (buf + pos);
+			pos += len;
+			done = 0;
+		} else {
+			for (x = buf + pos, i = 0;
+			     (*x == '_' || (*x >= 'a' && *x <= 'z')) &&
+			     i < MAX_MASK_NAME_LENGTH; x++, i++, pos++)
+				substring[i] = *x;
+			substring[i] = '\0';
+
+			for (i = 0; mask_flags[i].mask_name != NULL; i++) {
+				if (strcmp(substring, mask_flags[i].mask_name)
+				    == 0) {
+					mask_name = mask_flags[i].mask_name;
+					mask_bitfield =
+					    mask_flags[i].mask_bitfield;
+					done = 0;
+					break;
+				}
+			}
+		}
+
+		if (mask_name != NULL) {
+			done = 0;
+			switch (add) {
+			case '-':
+				rg &= ~mask_bitfield;
+				break;
+			case '+':
+				rg |= mask_bitfield;
+				break;
+			case '=':
+				rg = mask_bitfield;
+				break;
+			default:
+				rg |= mask_bitfield;
+				break;
+			}
+		}
+	}
+
+	yaffs_trace_mask = rg | YAFFS_TRACE_ALWAYS;
+
+	printk(KERN_DEBUG "new trace = 0x%08X\n", yaffs_trace_mask);
+
+	if (rg & YAFFS_TRACE_ALWAYS) {
+		for (i = 0; mask_flags[i].mask_name != NULL; i++) {
+			char flag;
+			flag = ((rg & mask_flags[i].mask_bitfield) ==
+				mask_flags[i].mask_bitfield) ? '+' : '-';
+			printk(KERN_DEBUG "%c%s\n", flag,
+			       mask_flags[i].mask_name);
+		}
+	}
+
+	return count;
+}
+
+static int yaffs_proc_write(struct file *file, const char *buf,
+			    unsigned long count, void *data)
+{
+	return yaffs_proc_write_trace_options(file, buf, count, data);
+}
+
+/* Stuff to handle installation of file systems */
+struct file_system_to_install {
+	struct file_system_type *fst;
+	int installed;
+};
+
+static struct file_system_to_install fs_to_install[] = {
+	{&yaffs_fs_type, 0},
+	{&yaffs2_fs_type, 0},
+	{NULL, 0}
+};
+
+static int __init init_yaffs_fs(void)
+{
+	int error = 0;
+	struct file_system_to_install *fsinst;
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"yaffs built " __DATE__ " " __TIME__ " Installing.");
+
+#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"\n\nYAFFS-WARNING CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED selected.\n\n\n");
+#endif
+
+	mutex_init(&yaffs_context_lock);
+
+	/* Install the proc_fs entries */
+	my_proc_entry = create_proc_entry("yaffs",
+					  S_IRUGO | S_IFREG, NULL);
+
+	if (my_proc_entry) {
+		my_proc_entry->write_proc = yaffs_proc_write;
+		my_proc_entry->read_proc = yaffs_proc_read;
+		my_proc_entry->data = NULL;
+	} else {
+		return -ENOMEM;
+	}
+
+
+	/* Now add the file system entries */
+
+	fsinst = fs_to_install;
+
+	while (fsinst->fst && !error) {
+		error = register_filesystem(fsinst->fst);
+		if (!error)
+			fsinst->installed = 1;
+		fsinst++;
+	}
+
+	/* Any errors? uninstall  */
+	if (error) {
+		fsinst = fs_to_install;
+
+		while (fsinst->fst) {
+			if (fsinst->installed) {
+				unregister_filesystem(fsinst->fst);
+				fsinst->installed = 0;
+			}
+			fsinst++;
+		}
+	}
+
+	return error;
+}
+
+static void __exit exit_yaffs_fs(void)
+{
+
+	struct file_system_to_install *fsinst;
+
+	yaffs_trace(YAFFS_TRACE_ALWAYS,
+		"yaffs built " __DATE__ " " __TIME__ " removing.");
+
+	remove_proc_entry("yaffs", NULL);
+
+	fsinst = fs_to_install;
+
+	while (fsinst->fst) {
+		if (fsinst->installed) {
+			unregister_filesystem(fsinst->fst);
+			fsinst->installed = 0;
+		}
+		fsinst++;
+	}
+}
+
+module_init(init_yaffs_fs)
+module_exit(exit_yaffs_fs)
+
+MODULE_DESCRIPTION("YAFFS2 - a NAND specific flash file system");
+MODULE_AUTHOR("Charles Manning, Aleph One Ltd., 2002-2011");
+MODULE_LICENSE("GPL");
diff --git a/fs/yaffs2/yportenv.h b/fs/yaffs2/yportenv.h
new file mode 100644
index 0000000..aa7c22b
--- /dev/null
+++ b/fs/yaffs2/yportenv.h
@@ -0,0 +1,59 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2011 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YPORTENV_LINUX_H__
+#define __YPORTENV_LINUX_H__
+
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/xattr.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <linux/sort.h>
+#include <linux/bitops.h>
+
+/*  These type wrappings are used to support Unicode names in WinCE. */
+#define YCHAR char
+#define YUCHAR unsigned char
+#define _Y(x)     x
+
+#define YAFFS_LOSTNFOUND_NAME		"lost+found"
+#define YAFFS_LOSTNFOUND_PREFIX		"obj"
+
+
+#define YAFFS_ROOT_MODE			0755
+#define YAFFS_LOSTNFOUND_MODE		0700
+
+#define Y_CURRENT_TIME CURRENT_TIME.tv_sec
+#define Y_TIME_CONVERT(x) (x).tv_sec
+
+#define compile_time_assertion(assertion) \
+	({ int x = __builtin_choose_expr(assertion, 0, (void)0); (void) x; })
+
+
+#define yaffs_trace(msk, fmt, ...) do { \
+	if (yaffs_trace_mask & (msk)) \
+		printk(KERN_DEBUG "yaffs: " fmt "\n", ##__VA_ARGS__); \
+} while (0)
+
+
+#endif
-- 
1.7.1

Re: [PATCH 09/10] Add yaffs2 file system: Linux glue code

[Ryan Mallon]

On 02/09/2011 04:26 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>

Hi Charles,

More comments below. The locking I think needs some work before this is
okay for mainline. It would be interesting to stress test yaffs on an
SMP machine. None of the boards which we run yaffs on are though :-(.

~Ryan

> ---
>  fs/yaffs2/yaffs_linux.h |   41 +
>  fs/yaffs2/yaffs_vfs.c   | 2745 +++++++++++++++++++++++++++++++++++++++++++++++
>  fs/yaffs2/yportenv.h    |   59 +
>  3 files changed, 2845 insertions(+), 0 deletions(-)
>  create mode 100644 fs/yaffs2/yaffs_linux.h
>  create mode 100644 fs/yaffs2/yaffs_vfs.c
>  create mode 100644 fs/yaffs2/yportenv.h
> 
> diff --git a/fs/yaffs2/yaffs_linux.h b/fs/yaffs2/yaffs_linux.h
> new file mode 100644
> index 0000000..8c522c8
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_linux.h
> @@ -0,0 +1,41 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2011 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YAFFS_LINUX_H__
> +#define __YAFFS_LINUX_H__
> +
> +#include "yportenv.h"
> +
> +struct yaffs_linux_context {
> +	struct list_head context_list;	/* List of these we have mounted */
> +	struct yaffs_dev *dev;
> +	struct super_block *super;
> +	struct task_struct *bg_thread;	/* Background thread for this device */
> +	int bg_running;
> +	struct mutex gross_lock;	/* Gross locking mutex*/
> +	u8 *spare_buffer;	/* For mtdif2 use. Don't know the buffer size
> +				 * at compile time so we have to allocate it.
> +				 */
> +	struct list_head search_contexts;
> +	void (*put_super_fn) (struct super_block *sb);
> +
> +	struct task_struct *readdir_process;
> +	unsigned mount_id;
> +};
> +
> +#define yaffs_dev_to_lc(dev) ((struct yaffs_linux_context *)((dev)->os_context))
> +#define yaffs_dev_to_mtd(dev) ((struct mtd_info *)((dev)->driver_context))
> +
> +#endif
> diff --git a/fs/yaffs2/yaffs_vfs.c b/fs/yaffs2/yaffs_vfs.c
> new file mode 100644
> index 0000000..724bd3f
> --- /dev/null
> +++ b/fs/yaffs2/yaffs_vfs.c
> @@ -0,0 +1,2745 @@
> +/*
> + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2011 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + * Acknowledgements:
> + * Luc van OostenRyck for numerous patches.
> + * Nick Bane for numerous patches.
> + * Nick Bane for 2.5/2.6 integration.
> + * Andras Toth for mknod rdev issue.
> + * Michael Fischer for finding the problem with inode inconsistency.
> + * Some code bodily lifted from JFFS
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +/*
> + *
> + * This is the file system front-end to YAFFS that hooks it up to
> + * the VFS.
> + *
> + * Special notes:
> + * >> 2.4: sb->u.generic_sbp points to the struct yaffs_dev associated with
> + *         this superblock
> + * >> 2.6: sb->s_fs_info  points to the struct yaffs_dev associated with this
> + *         superblock
> + * >> inode->u.generic_ip points to the associated struct yaffs_obj.
> + */
> +
> +/*
> + * NB There are two variants of Linux VFS glue code. This variant supports
> + * a single version and should not include any multi-version code.
> + */
> +#include <linux/version.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/fs.h>
> +#include <linux/proc_fs.h>
> +#include <linux/smp_lock.h>
> +#include <linux/pagemap.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/interrupt.h>
> +#include <linux/string.h>
> +#include <linux/ctype.h>
> +#include <linux/namei.h>
> +#include <linux/exportfs.h>
> +#include <linux/kthread.h>
> +#include <linux/delay.h>
> +#include <linux/freezer.h>
> +#include <asm/div64.h>
> +#include <linux/statfs.h>
> +#include <linux/uaccess.h>
> +#include <linux/mtd/mtd.h>
> +
> +#include "yportenv.h"
> +#include "yaffs_trace.h"
> +#include "yaffs_guts.h"
> +#include "yaffs_attribs.h"
> +#include "yaffs_linux.h"
> +#include "yaffs_mtdif.h"
> +#include "yaffs_mtdif1.h"
> +#include "yaffs_mtdif2.h"
> +
> +unsigned int yaffs_trace_mask = YAFFS_TRACE_BAD_BLOCKS | YAFFS_TRACE_ALWAYS;
> +unsigned int yaffs_wr_attempts = YAFFS_WR_ATTEMPTS;
> +unsigned int yaffs_auto_checkpoint = 1;
> +unsigned int yaffs_gc_control = 1;
> +unsigned int yaffs_bg_enable = 1;
> +
> +/* Module Parameters */
> +module_param(yaffs_trace_mask, uint, 0644);
> +module_param(yaffs_wr_attempts, uint, 0644);
> +module_param(yaffs_auto_checkpoint, uint, 0644);
> +module_param(yaffs_gc_control, uint, 0644);
> +module_param(yaffs_bg_enable, uint, 0644);
> +
> +#define yaffs_devname(sb, buf)	bdevname(sb->s_bdev, buf)
> +
> +static uint32_t YCALCBLOCKS(uint64_t partition_size, uint32_t block_size)
> +{
> +	uint64_t result = partition_size;
> +
> +	do_div(result, block_size);
> +	return (uint32_t) result;
> +}
> +
> +#define yaffs_inode_to_obj_lv(iptr) ((iptr)->i_private)
> +#define yaffs_inode_to_obj(iptr)\
> +	((struct yaffs_obj *)(yaffs_inode_to_obj_lv(iptr)))
> +#define yaffs_dentry_to_obj(dptr) yaffs_inode_to_obj((dptr)->d_inode)
> +#define yaffs_super_to_dev(sb)	((struct yaffs_dev *)sb->s_fs_info)
> +
> +#define update_dir_time(dir) do {\
> +			(dir)->i_ctime = (dir)->i_mtime = CURRENT_TIME; \
> +		} while (0)
> +
> +
> +static unsigned yaffs_gc_control_callback(struct yaffs_dev *dev)
> +{
> +	return yaffs_gc_control;
> +}
> +
> +static void yaffs_gross_lock(struct yaffs_dev *dev)
> +{
> +	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locking %p", current);
> +	mutex_lock(&(yaffs_dev_to_lc(dev)->gross_lock));
> +	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs locked %p", current);
> +}
> +
> +static void yaffs_gross_unlock(struct yaffs_dev *dev)
> +{
> +	yaffs_trace(YAFFS_TRACE_LOCK, "yaffs unlocking %p", current);
> +	mutex_unlock(&(yaffs_dev_to_lc(dev)->gross_lock));
> +}
> +
> +static void yaffs_fill_inode_from_obj(struct inode *inode,
> +				      struct yaffs_obj *obj);
> +
> +static struct inode *yaffs_iget(struct super_block *sb, unsigned long ino)
> +{
> +	struct inode *inode;
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_iget for %lu", ino);
> +
> +	inode = iget_locked(sb, ino);
> +	if (!inode)
> +		return ERR_PTR(-ENOMEM);
> +	if (!(inode->i_state & I_NEW))
> +		return inode;
> +
> +	/* NB This is called as a side effect of other functions, but
> +	 * we had to release the lock to prevent deadlocks, so
> +	 * need to lock again.
> +	 */
> +
> +	yaffs_gross_lock(dev);
> +
> +	obj = yaffs_find_by_number(dev, inode->i_ino);
> +	yaffs_fill_inode_from_obj(inode, obj);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	unlock_new_inode(inode);
> +	return inode;
> +}
> +
> +struct inode *yaffs_get_inode(struct super_block *sb, int mode, int dev,
> +			      struct yaffs_obj *obj)
> +{
> +	struct inode *inode;
> +
> +	if (!sb) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_get_inode for NULL super_block!!");
> +		return NULL;
> +
> +	}
> +
> +	if (!obj) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_get_inode for NULL object!!");
> +		return NULL;
> +
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_get_inode for object %d",
> +		obj->obj_id);
> +
> +	inode = yaffs_iget(sb, obj->obj_id);
> +	if (IS_ERR(inode))
> +		return NULL;
> +
> +	/* NB Side effect: iget calls back to yaffs_read_inode(). */
> +	/* iget also increments the inode's i_count */
> +	/* NB You can't be holding gross_lock or deadlock will happen! */
> +
> +	return inode;
> +}
> +
> +static int yaffs_mknod(struct inode *dir, struct dentry *dentry, int mode,
> +		       dev_t rdev)
> +{
> +	struct inode *inode;
> +	struct yaffs_obj *obj = NULL;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *parent = yaffs_inode_to_obj(dir);
> +	int error;
> +	uid_t uid = current->cred->fsuid;
> +	gid_t gid =
> +	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
> +
> +	if ((dir->i_mode & S_ISGID) && S_ISDIR(mode))
> +		mode |= S_ISGID;
> +
> +	if (!parent) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_mknod: could not get parent object");
> +		return -EPERM;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_mknod: parent object %d type %d",
> +			parent->obj_id, parent->variant_type);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_mknod: making oject for %s, mode %x dev %x",
> +		dentry->d_name.name, mode, rdev);
> +
> +	dev = parent->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	if (yaffs_get_n_free_chunks(dev) < 1) {
> +		error = -ENOSPC;
> +		goto err_out;
> +	}
> +
> +	switch (mode & S_IFMT) {
> +	default:
> +		/* Special (socket, fifo, device...) */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making special");
> +		obj =
> +		    yaffs_create_special(parent, dentry->d_name.name, mode, uid,
> +					 gid, old_encode_dev(rdev));
> +		break;
> +	case S_IFREG:		/* file          */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making file");
> +		obj = yaffs_create_file(parent, dentry->d_name.name, mode, uid,
> +					gid);
> +		break;
> +	case S_IFDIR:		/* directory */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making directory");
> +		obj = yaffs_create_dir(parent, dentry->d_name.name, mode,
> +				       uid, gid);
> +		break;
> +	case S_IFLNK:		/* symlink */
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod: making symlink");
> +		obj = NULL;	/* Do we ever get here? */
> +		break;
> +	}
> +
> +	if (!obj) {
> +		error = -ENOMEM;
> +		goto err_out;
> +	}
> +
> +	/* Can not call yaffs_get_inode() with gross lock held */
> +	yaffs_gross_unlock(dev);
> +
> +
> +	inode = yaffs_get_inode(dir->i_sb, mode, rdev, obj);
> +	d_instantiate(dentry, inode);
> +	update_dir_time(dir);
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_mknod created object %d count = %d",
> +		obj->obj_id, atomic_read(&inode->i_count));
> +	yaffs_fill_inode_from_obj(dir, parent);
> +	return 0;
> +
> +err_out:
> +	yaffs_gross_unlock(dev);
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_mknod error %d", error);
> +	return error;
> +
> +}
> +
> +static int yaffs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
> +{
> +	return yaffs_mknod(dir, dentry, mode | S_IFDIR, 0);
> +}
> +
> +static int yaffs_create(struct inode *dir, struct dentry *dentry, int mode,
> +			struct nameidata *n)
> +{
> +	return yaffs_mknod(dir, dentry, mode | S_IFREG, 0);
> +}
> +

It's often ideal to have a single return statement from a function,
which makes it easier to verify that all paths through the code clean
themselves up correctly. See below:

> +static int yaffs_link(struct dentry *old_dentry, struct inode *dir,
> +		      struct dentry *dentry)
> +{
> +	struct inode *inode = old_dentry->d_inode;
> +	struct yaffs_obj *obj = NULL;
> +	struct yaffs_obj *link = NULL;
> +	struct yaffs_dev *dev;

	int ret = 0;

> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_link");
> +
> +	obj = yaffs_inode_to_obj(inode);
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	if (!S_ISDIR(inode->i_mode))	/* Don't link directories */
> +		link =
> +		    yaffs_link_obj(yaffs_inode_to_obj(dir), dentry->d_name.name,
> +				   obj);
> +
> +	if (link) {

	if (!link) {
		yaffs_gross_unlock(dev);
		ret = -EPERM;
		goto out;
	}

> +		old_dentry->d_inode->i_nlink = yaffs_get_obj_link_count(obj);
> +		d_instantiate(dentry, old_dentry->d_inode);
> +		atomic_inc(&old_dentry->d_inode->i_count);
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_link link count %d i_count %d",
> +			old_dentry->d_inode->i_nlink,
> +			atomic_read(&old_dentry->d_inode->i_count));
> +	}
> +
> +	yaffs_gross_unlock(dev);
> +
> +	if (link) {

Don't need this if statement.	

> +		update_dir_time(dir);
> +		return 0;
> +	}
> +
> +	return -EPERM;

  out:
	return ret;

> +}
> +
> +static int yaffs_symlink(struct inode *dir, struct dentry *dentry,
> +			 const char *symname)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	struct inode *inode;
> +	uid_t uid = current->cred->fsuid;
> +	gid_t gid =
> +	    (dir->i_mode & S_ISGID) ? dir->i_gid : current->cred->fsgid;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_symlink");
> +
> +	dev = yaffs_inode_to_obj(dir)->my_dev;
> +	yaffs_gross_lock(dev);
> +	obj = yaffs_create_symlink(yaffs_inode_to_obj(dir), dentry->d_name.name,
> +				   S_IFLNK | S_IRWXUGO, uid, gid, symname);
> +	yaffs_gross_unlock(dev);

What does yaffs_gross_lock actually protect? yaffs_create_symlink calls
yaffs_create_obj, which looks like large parts of it can be run safely
without the lock held. Probably the lock just needs to be around the
entry of the new object, not the creation right?

Pushing the lock down into the functions it is around in this file will
make it more obvious what the lock is protecting and make it easier to
replace it with a more fine grained locking approach.

> +
> +	if (!obj) {
> +		yaffs_trace(YAFFS_TRACE_OS, "symlink not created");
> +		return -ENOMEM;
> +	}
> +
> +	inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
> +	d_instantiate(dentry, inode);
> +	update_dir_time(dir);
> +	yaffs_trace(YAFFS_TRACE_OS, "symlink created OK");
> +
> +	return 0;
> +}
> +
> +static struct dentry *yaffs_lookup(struct inode *dir, struct dentry *dentry,
> +				   struct nameidata *n)
> +{
> +	struct yaffs_obj *obj;
> +	struct inode *inode = NULL;
> +	struct yaffs_dev *dev = yaffs_inode_to_obj(dir)->my_dev;
> +
> +	if (current != yaffs_dev_to_lc(dev)->readdir_process)
> +		yaffs_gross_lock(dev);

How come you don't need to acquire the lock if we are the
readdir_process? This implies that the locking is messed up somewhere
and this code exists to prevent a deadlock when call into this function
within the same process by another function which is already holding the
lock? This can lead to buggy code if the calling function is ever
changed and we end up not holding the lock here when we should be.

If this is the case then the locking should be fixed so that these kind
of situations don't happen (e.g. by pushing the lock down to the actual
bits it protects). If there is another reason why the lock is
selectively taken here then there should at least be a comment
explaining the behaviour.

> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_lookup for %d:%s",
> +		yaffs_inode_to_obj(dir)->obj_id, dentry->d_name.name);
> +
> +	obj = yaffs_find_by_name(yaffs_inode_to_obj(dir), dentry->d_name.name);
> +
> +	obj = yaffs_get_equivalent_obj(obj);	/* in case it was a hardlink */

Pushing the lock down into these functions, which probably reduces it to
being around the actual object lookup, will remove the need to
temporarily release the lock while calling yaffs_get_inode below.

> +
> +	/* Can't hold gross lock when calling yaffs_get_inode() */
> +	if (current != yaffs_dev_to_lc(dev)->readdir_process)
> +		yaffs_gross_unlock(dev);
> +
> +	if (obj) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_lookup found %d", obj->obj_id);
> +
> +		inode = yaffs_get_inode(dir->i_sb, obj->yst_mode, 0, obj);
> +
> +		if (inode) {
> +			yaffs_trace(YAFFS_TRACE_OS, "yaffs_loookup dentry");
> +			d_add(dentry, inode);
> +			/* return dentry; */
> +			return NULL;
> +		}
> +
> +	} else {
> +		yaffs_trace(YAFFS_TRACE_OS, "yaffs_lookup not found");
> +
> +	}
> +
> +	d_add(dentry, inode);
> +
> +	return NULL;
> +}
> +
> +static int yaffs_unlink(struct inode *dir, struct dentry *dentry)
> +{
> +	int ret_val;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_unlink %d:%s",
> +		(int)(dir->i_ino), dentry->d_name.name);
> +	obj = yaffs_inode_to_obj(dir);
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	ret_val = yaffs_unlinker(obj, dentry->d_name.name);
> +
> +	if (ret_val == YAFFS_OK) {
> +		dentry->d_inode->i_nlink--;
> +		dir->i_version++;

I don't know the full details of the filesystem locking, but I get the
impression that the above two statements should already be protected by
the vfs locks? If so the yaffs gross lock should be just protecting
yaffs_unlinker (and ideally pushed down into it).

> +		yaffs_gross_unlock(dev);
> +		mark_inode_dirty(dentry->d_inode);
> +		update_dir_time(dir);
> +		return 0;
> +	}
> +	yaffs_gross_unlock(dev);
> +	return -ENOTEMPTY;
> +}
> +
> +static int yaffs_sync_object(struct file *file, int datasync)
> +{
> +
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	struct dentry *dentry = file->f_path.dentry;
> +
> +	obj = yaffs_dentry_to_obj(dentry);
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC, "yaffs_sync_object");
> +	yaffs_gross_lock(dev);
> +	yaffs_flush_file(obj, 1, datasync);
> +	yaffs_gross_unlock(dev);
> +	return 0;
> +}
> +/*
> + * The VFS layer already does all the dentry stuff for rename.
> + *
> + * NB: POSIX says you can rename an object over an old object of the same name
> + */
> +static int yaffs_rename(struct inode *old_dir, struct dentry *old_dentry,
> +			struct inode *new_dir, struct dentry *new_dentry)
> +{
> +	struct yaffs_dev *dev;
> +	int ret_val = YAFFS_FAIL;
> +	struct yaffs_obj *target;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_rename");
> +	dev = yaffs_inode_to_obj(old_dir)->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	/* Check if the target is an existing directory that is not empty. */
> +	target = yaffs_find_by_name(yaffs_inode_to_obj(new_dir),
> +				    new_dentry->d_name.name);
> +
> +	if (target && target->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY &&
> +	    !list_empty(&target->variant.dir_variant.children)) {
> +
> +		yaffs_trace(YAFFS_TRACE_OS, "target is non-empty dir");
> +
> +		ret_val = YAFFS_FAIL;
> +	} else {
> +		/* Now does unlinking internally using shadowing mechanism */
> +		yaffs_trace(YAFFS_TRACE_OS, "calling yaffs_rename_obj");
> +
> +		ret_val = yaffs_rename_obj(yaffs_inode_to_obj(old_dir),
> +					   old_dentry->d_name.name,
> +					   yaffs_inode_to_obj(new_dir),
> +					   new_dentry->d_name.name);
> +	}
> +	yaffs_gross_unlock(dev);

Looks like the lock should just be around (pushed down into)
yaffs_find_by_name and yaffs_rename_obj.

> +
> +	if (ret_val == YAFFS_OK) {
> +		if (target) {
> +			new_dentry->d_inode->i_nlink--;

Okay, we did this above with gross lock held, now we do it without
holding the lock.

> +			mark_inode_dirty(new_dentry->d_inode);
> +		}
> +
> +		update_dir_time(old_dir);
> +		if (old_dir != new_dir)
> +			update_dir_time(new_dir);
> +		return 0;
> +	} else {
> +		return -ENOTEMPTY;
> +	}
> +}
> +
> +static int yaffs_setattr(struct dentry *dentry, struct iattr *attr)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error = 0;
> +	struct yaffs_dev *dev;
> +	int result;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_setattr of object %d",
> +		yaffs_inode_to_obj(inode)->obj_id);
> +
> +	/* Fail if a requested resize >= 2GB */
> +	if (attr->ia_valid & ATTR_SIZE && (attr->ia_size >> 31))
> +		error = -EINVAL;
> +
> +	if (!error)
> +		error = inode_change_ok(inode, attr);
> +
> +	if (!error) {
> +		setattr_copy(inode, attr);
> +		yaffs_trace(YAFFS_TRACE_OS, "inode_setattr called");
> +		if (attr->ia_valid & ATTR_SIZE) {
> +			truncate_setsize(inode, attr->ia_size);
> +			inode->i_blocks = (inode->i_size + 511) >> 9;
> +		}
> +		dev = yaffs_inode_to_obj(inode)->my_dev;
> +		if (attr->ia_valid & ATTR_SIZE) {
> +			yaffs_trace(YAFFS_TRACE_OS, "resize to %d(%x)",
> +					   (int)(attr->ia_size),
> +					   (int)(attr->ia_size));
> +		}
> +
> +		yaffs_gross_lock(dev);
> +		result = yaffs_set_attribs(yaffs_inode_to_obj(inode), attr);
> +		if (result != YAFFS_OK)
> +			error = -EPERM;
> +		yaffs_gross_unlock(dev);
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +#ifdef CONFIG_YAFFS_XATTR
> +static int yaffs_setxattr(struct dentry *dentry, const char *name,
> +		   const void *value, size_t size, int flags)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr of object %d", obj->obj_id);
> +
> +	dev = obj->my_dev;
> +	yaffs_gross_lock(dev);
> +	error = yaffs_set_xattrib(obj, name, value, size, flags);
> +	yaffs_gross_unlock(dev);

This should almost definitely be a separate lock to the other
operations. Shouldn't need to lock the whole filesystem to update an
attribute on a single object, at least not for the entire operation.

> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_setxattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +static ssize_t yaffs_getxattr(struct dentry *dentry, const char *name,
> +				void *buff, size_t size)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_getxattr \"%s\" from object %d",
> +		name, obj->obj_id);
> +
> +	dev = obj->my_dev;
> +	yaffs_gross_lock(dev);
> +	error = yaffs_get_xattrib(obj, name, buff, size);
> +	yaffs_gross_unlock(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_getxattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +static int yaffs_removexattr(struct dentry *dentry, const char *name)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_removexattr of object %d", obj->obj_id);
> +
> +	dev = obj->my_dev;
> +	yaffs_gross_lock(dev);
> +	error = yaffs_remove_xattrib(obj, name);
> +	yaffs_gross_unlock(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_removexattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +static ssize_t yaffs_listxattr(struct dentry *dentry, char *buff, size_t size)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	int error;
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_listxattr of object %d", obj->obj_id);
> +
> +	dev = obj->my_dev;
> +	yaffs_gross_lock(dev);
> +	error = yaffs_list_xattrib(obj, buff, size);
> +	yaffs_gross_unlock(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_listxattr done returning %d", error);
> +
> +	return error;
> +}
> +
> +#endif
> +
> +static const struct inode_operations yaffs_dir_inode_operations = {
> +	.create = yaffs_create,
> +	.lookup = yaffs_lookup,
> +	.link = yaffs_link,
> +	.unlink = yaffs_unlink,
> +	.symlink = yaffs_symlink,
> +	.mkdir = yaffs_mkdir,
> +	.rmdir = yaffs_unlink,
> +	.mknod = yaffs_mknod,
> +	.rename = yaffs_rename,
> +	.setattr = yaffs_setattr,
> +#ifdef CONFIG_YAFFS_XATTR
> +	.setxattr = yaffs_setxattr,
> +	.getxattr = yaffs_getxattr,
> +	.listxattr = yaffs_listxattr,
> +	.removexattr = yaffs_removexattr,
> +#endif

Nitpick. Tab delimiting struct initialisations makes them easier to read.

> +};
> +/*-----------------------------------------------------------------*/
> +/* Directory search context allows us to unlock access to yaffs during
> + * filldir without causing problems with the directory being modified.
> + * This is similar to the tried and tested mechanism used in yaffs direct.
> + *
> + * A search context iterates along a doubly linked list of siblings in the
> + * directory. If the iterating object is deleted then this would corrupt
> + * the list iteration, likely causing a crash. The search context avoids
> + * this by using the remove_obj_fn to move the search context to the
> + * next object before the object is deleted.
> + *
> + * Many readdirs (and thus seach conexts) may be alive simulateously so
> + * each struct yaffs_dev has a list of these.
> + *
> + * A seach context lives for the duration of a readdir.
> + *
> + * All these functions must be called while yaffs is locked.
> + */
> +
> +struct yaffs_search_context {
> +	struct yaffs_dev *dev;
> +	struct yaffs_obj *dir_obj;
> +	struct yaffs_obj *next_return;
> +	struct list_head others;
> +};
> +
> +/*
> + * yaffs_new_search() creates a new search context, initialises it and
> + * adds it to the device's search context list.
> + *
> + * Called at start of readdir.
> + */
> +static struct yaffs_search_context *yaffs_new_search(struct yaffs_obj *dir)
> +{
> +	struct yaffs_dev *dev = dir->my_dev;
> +	struct yaffs_search_context *sc =
> +	    kmalloc(sizeof(struct yaffs_search_context), GFP_NOFS);
> +
> +	if (!sc)
> +		return NULL;
> +
> +	sc->dir_obj = dir;
> +	sc->dev = dev;
> +	if (list_empty(&sc->dir_obj->variant.dir_variant.children))
> +		sc->next_return = NULL;
> +	else
> +		sc->next_return =
> +		    list_entry(dir->variant.dir_variant.children.next,
> +			       struct yaffs_obj, siblings);
> +	INIT_LIST_HEAD(&sc->others);
> +	list_add(&sc->others, &(yaffs_dev_to_lc(dev)->search_contexts));
> +
> +	return sc;
> +}
> +
> +/*
> + * yaffs_search_end() disposes of a search context and cleans up.
> + */
> +static void yaffs_search_end(struct yaffs_search_context *sc)
> +{
> +	if (sc) {
> +		list_del(&sc->others);
> +		kfree(sc);
> +	}
> +}
> +
> +/*
> + * yaffs_search_advance() moves a search context to the next object.
> + * Called when the search iterates or when an object removal causes
> + * the search context to be moved to the next object.
> + */
> +static void yaffs_search_advance(struct yaffs_search_context *sc)
> +{
> +	if (!sc)
> +		return;
> +
> +	if (sc->next_return == NULL ||
> +	    list_empty(&sc->dir_obj->variant.dir_variant.children))
> +		sc->next_return = NULL;
> +	else {
> +		struct list_head *next = sc->next_return->siblings.next;
> +
> +		if (next == &sc->dir_obj->variant.dir_variant.children)
> +			sc->next_return = NULL;	/* end of list */
> +		else
> +			sc->next_return =
> +			    list_entry(next, struct yaffs_obj, siblings);
> +	}
> +}
> +
> +/*
> + * yaffs_remove_obj_callback() is called when an object is unlinked.
> + * We check open search contexts and advance any which are currently
> + * on the object being iterated.
> + */
> +static void yaffs_remove_obj_callback(struct yaffs_obj *obj)
> +{
> +
> +	struct list_head *i;
> +	struct yaffs_search_context *sc;
> +	struct list_head *search_contexts =
> +	    &(yaffs_dev_to_lc(obj->my_dev)->search_contexts);
> +
> +	/* Iterate through the directory search contexts.
> +	 * If any are currently on the object being removed, then advance
> +	 * the search context to the next object to prevent a hanging pointer.
> +	 */
> +	list_for_each(i, search_contexts) {
> +		sc = list_entry(i, struct yaffs_search_context, others);

list_for_each_entry.

> +		if (sc->next_return == obj)
> +			yaffs_search_advance(sc);
> +	}
> +
> +}
> +
> +static int yaffs_readdir(struct file *f, void *dirent, filldir_t filldir)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	struct yaffs_search_context *sc;
> +	struct inode *inode = f->f_dentry->d_inode;
> +	unsigned long offset, curoffs;
> +	struct yaffs_obj *l;
> +	int ret_val = 0;
> +	char name[YAFFS_MAX_NAME_LENGTH + 1];
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_dev_to_lc(dev)->readdir_process = current;
> +
> +	offset = f->f_pos;
> +
> +	sc = yaffs_new_search(obj);
> +	if (!sc) {
> +		ret_val = -ENOMEM;
> +		goto out;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_readdir: starting at %d", (int)offset);
> +
> +	if (offset == 0) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_readdir: entry . ino %d",
> +			(int)inode->i_ino);
> +		yaffs_gross_unlock(dev);
> +		if (filldir(dirent, ".", 1, offset, inode->i_ino, DT_DIR) < 0) {
> +			yaffs_gross_lock(dev);
> +			goto out;
> +		}
> +		yaffs_gross_lock(dev);
> +		offset++;
> +		f->f_pos++;

offset is local and f->f_pos is protected by vfs locks? (other
filesystems don't lock around it), so the lock doesn't need to be held
here. We release it a few lines down in the offset = 1 case anyway.

> +	}
> +	if (offset == 1) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_readdir: entry .. ino %d",
> +			(int)f->f_dentry->d_parent->d_inode->i_ino);
> +		yaffs_gross_unlock(dev);
> +		if (filldir(dirent, "..", 2, offset,
> +			    f->f_dentry->d_parent->d_inode->i_ino,
> +			    DT_DIR) < 0) {
> +			yaffs_gross_lock(dev);
> +			goto out;
> +		}
> +		yaffs_gross_lock(dev);
> +		offset++;
> +		f->f_pos++;
> +	}
> +
> +	curoffs = 1;
> +
> +	/* If the directory has changed since the open or last call to
> +	   readdir, rewind to after the 2 canned entries. */
> +	if (f->f_version != inode->i_version) {
> +		offset = 2;
> +		f->f_pos = offset;
> +		f->f_version = inode->i_version;
> +	}

We probably don't need to hold the yaffs lock across any of this.

> +
> +	while (sc->next_return) {
> +		curoffs++;
> +		l = sc->next_return;
> +		if (curoffs >= offset) {
> +			int this_inode = yaffs_get_obj_inode(l);
> +			int this_type = yaffs_get_obj_type(l);

We call yaffs_get_obj_inode elsewhere without the lock held and
yaffs_get_obj_type doesn't do anything that would require the entire
filesystem to be locked, so we probably don't need the lock held here.

> +
> +			yaffs_get_obj_name(l, name, YAFFS_MAX_NAME_LENGTH + 1);

We may need it here, but fine grained locking inside yaffs_guts would be
more ideal.

> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"yaffs_readdir: %s inode %d",
> +				name, yaffs_get_obj_inode(l));
> +
> +			yaffs_gross_unlock(dev);
> +
> +			if (filldir(dirent,
> +				    name,
> +				    strlen(name),
> +				    offset, this_inode, this_type) < 0) {
> +				yaffs_gross_lock(dev);
> +				goto out;
> +			}
> +
> +			yaffs_gross_lock(dev);
> +
> +			offset++;
> +			f->f_pos++;

Don't need it here. So I think the lock can at least be reduced to being
around yaffs_get_obj_name in this loop, yaffs_new_search above and
yaffs_search_advance/yaffs_search_end and the setting of readdir_process
below.

> +		}
> +		yaffs_search_advance(sc);
> +	}
> +
> +out:
> +	yaffs_search_end(sc);
> +	yaffs_dev_to_lc(dev)->readdir_process = NULL;
> +	yaffs_gross_unlock(dev);
> +
> +	return ret_val;
> +}
> +
> +static const struct file_operations yaffs_dir_operations = {
> +	.read = generic_read_dir,
> +	.readdir = yaffs_readdir,
> +	.fsync = yaffs_sync_object,
> +	.llseek = generic_file_llseek,
> +};

Nitpick. Tab delimit.

> +
> +
> +
> +static int yaffs_file_flush(struct file *file, fl_owner_t id)
> +{
> +	struct yaffs_obj *obj = yaffs_dentry_to_obj(file->f_dentry);
> +	struct yaffs_dev *dev = obj->my_dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_file_flush object %d (%s)",
> +		obj->obj_id, obj->dirty ? "dirty" : "clean");
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_flush_file(obj, 1, 0);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	return 0;
> +}
> +
> +static const struct file_operations yaffs_file_operations = {
> +	.read = do_sync_read,
> +	.write = do_sync_write,
> +	.aio_read = generic_file_aio_read,
> +	.aio_write = generic_file_aio_write,
> +	.mmap = generic_file_mmap,
> +	.flush = yaffs_file_flush,
> +	.fsync = yaffs_sync_object,
> +	.splice_read = generic_file_splice_read,
> +	.splice_write = generic_file_splice_write,
> +	.llseek = generic_file_llseek,
> +};

Nitpick. Tab delimit.

> +
> +
> +/* ExportFS support */
> +static struct inode *yaffs2_nfs_get_inode(struct super_block *sb, uint64_t ino,
> +					  uint32_t generation)
> +{
> +	return yaffs_iget(sb, ino);
> +}
> +
> +static struct dentry *yaffs2_fh_to_dentry(struct super_block *sb,
> +					  struct fid *fid, int fh_len,
> +					  int fh_type)
> +{
> +	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
> +				    yaffs2_nfs_get_inode);
> +}
> +
> +static struct dentry *yaffs2_fh_to_parent(struct super_block *sb,
> +					  struct fid *fid, int fh_len,
> +					  int fh_type)
> +{
> +	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
> +				    yaffs2_nfs_get_inode);
> +}
> +
> +struct dentry *yaffs2_get_parent(struct dentry *dentry)
> +{
> +
> +	struct super_block *sb = dentry->d_inode->i_sb;
> +	struct dentry *parent = ERR_PTR(-ENOENT);

Don't init this.

> +	struct inode *inode;
> +	unsigned long parent_ino;
> +	struct yaffs_obj *d_obj;
> +	struct yaffs_obj *parent_obj;
> +
> +	d_obj = yaffs_inode_to_obj(dentry->d_inode);
> +

	if (!d_obj)
		return -ERR_PTR(-ENOENT);

> +	if (d_obj) {
> +		parent_obj = d_obj->parent;
> +		if (parent_obj) {

		if (!parent_obj)
			return -ERR_PTR(-ENOENT);

> +			parent_ino = yaffs_get_obj_inode(parent_obj);
> +			inode = yaffs_iget(sb, parent_ino);
> +
> +			if (IS_ERR(inode)) {
> +				parent = ERR_CAST(inode);
		
			if (IS_ERR(inode))
				return ERR_CAST(inode);

> +			} else {
> +				parent = d_obtain_alias(inode);
> +				if (!IS_ERR(parent)) {
> +					parent = ERR_PTR(-ENOMEM);
> +					iput(inode);
				
					return ERR_PTR(-ENOMEM);
> +				}
> +			}
> +		}
> +	}
> +	return parent;

You alternatively set parent and have gotos if you want to retain the
single return statement.

> +}
> +
> +/* Just declare a zero structure as a NULL value implies
> + * using the default functions of exportfs.
> + */
> +
> +static struct export_operations yaffs_export_ops = {
> +	.fh_to_dentry = yaffs2_fh_to_dentry,
> +	.fh_to_parent = yaffs2_fh_to_parent,
> +	.get_parent = yaffs2_get_parent,
> +};
> +
> +
> +/*-----------------------------------------------------------------*/
> +
> +static int yaffs_readlink(struct dentry *dentry, char __user * buffer,
> +			  int buflen)
> +{
> +	unsigned char *alias;
> +	int ret;
> +	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
> +
> +	yaffs_gross_unlock(dev);
> +
> +	if (!alias)
> +		return -ENOMEM;
> +
> +	ret = vfs_readlink(dentry, buffer, buflen, alias);
> +	kfree(alias);
> +	return ret;
> +}
> +
> +static void *yaffs_follow_link(struct dentry *dentry, struct nameidata *nd)
> +{
> +	unsigned char *alias;
> +	void *ret;
> +	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	alias = yaffs_get_symlink_alias(yaffs_dentry_to_obj(dentry));
> +	yaffs_gross_unlock(dev);
> +
> +	if (!alias) {
> +		ret = ERR_PTR(-ENOMEM);
> +		goto out;
> +	}
> +
> +	nd_set_link(nd, alias);
> +	ret = (void *)alias;

No need for the cast.

> +out:
> +	return ret;
> +}
> +
> +void yaffs_put_link(struct dentry *dentry, struct nameidata *nd, void *alias)
> +{
> +	kfree(alias);
> +}
> +
> +
> +static void yaffs_unstitch_obj(struct inode *inode, struct yaffs_obj *obj)
> +{
> +	/* Clear the association between the inode and
> +	 * the struct yaffs_obj.
> +	 */
> +	obj->my_inode = NULL;
> +	yaffs_inode_to_obj_lv(inode) = NULL;
> +
> +	/* If the object freeing was deferred, then the real
> +	 * free happens now.
> +	 * This should fix the inode inconsistency problem.
> +	 */
> +	yaffs_handle_defered_free(obj);
> +}
> +
> +/* yaffs_evict_inode combines into one operation what was previously done in
> + * yaffs_clear_inode() and yaffs_delete_inode()
> + *
> + */
> +static void yaffs_evict_inode(struct inode *inode)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	int deleteme = 0;
> +
> +	obj = yaffs_inode_to_obj(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_evict_inode: ino %d, count %d %s",
> +		(int)inode->i_ino,
> +		atomic_read(&inode->i_count),
> +		obj ? "object exists" : "null object");
> +
> +	if (!inode->i_nlink && !is_bad_inode(inode))
> +		deleteme = 1;
> +	truncate_inode_pages(&inode->i_data, 0);
> +	end_writeback(inode);
> +
> +	if (deleteme && obj) {
> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		yaffs_del_obj(obj);
> +		yaffs_gross_unlock(dev);
> +	}
> +	if (obj) {
> +		dev = obj->my_dev;
> +		yaffs_gross_lock(dev);
> +		yaffs_unstitch_obj(inode, obj);
> +		yaffs_gross_unlock(dev);
> +	}
> +
> +}
> +
> +static void yaffs_touch_super(struct yaffs_dev *dev)
> +{
> +	struct super_block *sb = yaffs_dev_to_lc(dev)->super;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_touch_super() sb = %p", sb);
> +	if (sb)
> +		sb->s_dirt = 1;

Does this need lock/unlock_super around it?

> +}
> +
> +static int yaffs_readpage_nolock(struct file *f, struct page *pg)
> +{
> +	/* Lifted from jffs2 */
> +
> +	struct yaffs_obj *obj;
> +	unsigned char *pg_buf;
> +	int ret;
> +	struct yaffs_dev *dev;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_readpage_nolock at %08x, size %08x",
> +		(unsigned)(pg->index << PAGE_CACHE_SHIFT),
> +		(unsigned)PAGE_CACHE_SIZE);
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	dev = obj->my_dev;
> +
> +	BUG_ON(!PageLocked(pg));
> +
> +	pg_buf = kmap(pg);
> +	/* FIXME: Can kmap fail? */
> +
> +	yaffs_gross_lock(dev);
> +
> +	ret = yaffs_file_rd(obj, pg_buf,
> +			    pg->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	if (ret >= 0)
> +		ret = 0;
> +
> +	if (ret) {
> +		ClearPageUptodate(pg);
> +		SetPageError(pg);
> +	} else {
> +		SetPageUptodate(pg);
> +		ClearPageError(pg);
> +	}
> +
> +	flush_dcache_page(pg);
> +	kunmap(pg);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage_nolock done");
> +	return ret;
> +}
> +
> +static int yaffs_readpage_unlock(struct file *f, struct page *pg)
> +{
> +	int ret = yaffs_readpage_nolock(f, pg);
> +
> +	unlock_page(pg);
> +	return ret;
> +}
> +
> +static int yaffs_readpage(struct file *f, struct page *pg)
> +{
> +	int ret;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage");
> +	ret = yaffs_readpage_unlock(f, pg);
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_readpage done");
> +	return ret;

This looks a bit odd, but jffs2 does it this way too (with an additonal
lock held).

> +}
> +
> +/* writepage inspired by/stolen from smbfs */
> +
> +static int yaffs_writepage(struct page *page, struct writeback_control *wbc)
> +{
> +	struct yaffs_dev *dev;
> +	struct address_space *mapping = page->mapping;
> +	struct inode *inode;
> +	unsigned long end_index;
> +	char *buffer;
> +	struct yaffs_obj *obj;
> +	int n_written = 0;
> +	unsigned n_bytes;
> +	loff_t i_size;
> +
> +	if (!mapping)
> +		BUG();
> +	inode = mapping->host;
> +	if (!inode)
> +		BUG();
> +	i_size = i_size_read(inode);
> +
> +	end_index = i_size >> PAGE_CACHE_SHIFT;
> +
> +	if (page->index < end_index)
> +		n_bytes = PAGE_CACHE_SIZE;
> +	else {
> +		n_bytes = i_size & (PAGE_CACHE_SIZE - 1);
> +
> +		if (page->index > end_index || !n_bytes) {
> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"yaffs_writepage at %08x, inode size = %08x!!!",
> +				(unsigned)(page->index << PAGE_CACHE_SHIFT),
> +				(unsigned)inode->i_size);
> +			yaffs_trace(YAFFS_TRACE_OS,
> +			  "                -> don't care!!");
> +
> +			zero_user_segment(page, 0, PAGE_CACHE_SIZE);
> +			set_page_writeback(page);
> +			unlock_page(page);
> +			end_page_writeback(page);
> +			return 0;
> +		}
> +	}
> +
> +	if (n_bytes != PAGE_CACHE_SIZE)
> +		zero_user_segment(page, n_bytes, PAGE_CACHE_SIZE);
> +
> +	get_page(page);
> +
> +	buffer = kmap(page);
> +
> +	obj = yaffs_inode_to_obj(inode);
> +	dev = obj->my_dev;
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_writepage at %08x, size %08x",
> +		(unsigned)(page->index << PAGE_CACHE_SHIFT), n_bytes);
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"writepag0: obj = %05x, ino = %05x",
> +		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
> +
> +	n_written = yaffs_wr_file(obj, buffer,
> +				  page->index << PAGE_CACHE_SHIFT, n_bytes, 0);
> +
> +	yaffs_touch_super(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"writepag1: obj = %05x, ino = %05x",
> +		(int)obj->variant.file_variant.file_size, (int)inode->i_size);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	kunmap(page);
> +	set_page_writeback(page);
> +	unlock_page(page);
> +	end_page_writeback(page);
> +	put_page(page);
> +
> +	return (n_written == n_bytes) ? 0 : -ENOSPC;
> +}
> +
> +/* Space holding and freeing is done to ensure we have space available for
> + * write_begin/end.
> + * For now we just assume few parallel writes and check against a small
> + * number.
> + * Todo: need to do this with a counter to handle parallel reads better
> + */
> +
> +static ssize_t yaffs_hold_space(struct file *f)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +	int n_free_chunks;
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	n_free_chunks = yaffs_get_n_free_chunks(dev);
> +
> +	yaffs_gross_unlock(dev);
> +
> +	return (n_free_chunks > 20) ? 1 : 0;
> +}
> +
> +static void yaffs_release_space(struct file *f)
> +{
> +	struct yaffs_obj *obj;
> +	struct yaffs_dev *dev;
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_gross_unlock(dev);

What is this for? Delete it.

> +}
> +
> +static int yaffs_write_begin(struct file *filp, struct address_space *mapping,
> +			     loff_t pos, unsigned len, unsigned flags,
> +			     struct page **pagep, void **fsdata)
> +{
> +	struct page *pg = NULL;
> +	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
> +	int ret = 0;
> +	int space_held = 0;
> +
> +	/* Get a page */
> +	pg = grab_cache_page_write_begin(mapping, index, flags);
> +
> +	*pagep = pg;
> +	if (!pg) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"start yaffs_write_begin index %d(%x) uptodate %d",
> +		(int)index, (int)index, PageUptodate(pg) ? 1 : 0);
> +
> +	/* Get fs space */
> +	space_held = yaffs_hold_space(filp);
> +
> +	if (!space_held) {
> +		ret = -ENOSPC;
> +		goto out;
> +	}
> +
> +	/* Update page if required */
> +
> +	if (!PageUptodate(pg))
> +		ret = yaffs_readpage_nolock(filp, pg);
> +
> +	if (ret)
> +		goto out;
> +
> +	/* Happy path return */
> +	yaffs_trace(YAFFS_TRACE_OS, "end yaffs_write_begin - ok");
> +
> +	return 0;
> +
> +out:
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"end yaffs_write_begin fail returning %d", ret);
> +	if (space_held)
> +		yaffs_release_space(filp);
> +	if (pg) {
> +		unlock_page(pg);
> +		page_cache_release(pg);
> +	}
> +	return ret;
> +}
> +
> +static ssize_t yaffs_file_write(struct file *f, const char *buf, size_t n,
> +				loff_t *pos)
> +{
> +	struct yaffs_obj *obj;
> +	int n_written, ipos;
> +	struct inode *inode;
> +	struct yaffs_dev *dev;
> +
> +	obj = yaffs_dentry_to_obj(f->f_dentry);
> +
> +	if (!obj) {
> +		/* This should not happen */
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_file_write: hey obj is null!");
> +		return -EINVAL;
> +	}
> +
> +	dev = obj->my_dev;
> +
> +	yaffs_gross_lock(dev);
> +
> +	inode = f->f_dentry->d_inode;
> +
> +	if (!S_ISBLK(inode->i_mode) && f->f_flags & O_APPEND)
> +		ipos = inode->i_size;
> +	else
> +		ipos = *pos;

Do we need gross lock around this? Seems like it should be protected by
the inode's lock.

> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_file_write about to write writing %u(%x) bytes to object %d at %d(%x)",
> +		(unsigned)n, (unsigned)n, obj->obj_id, ipos, ipos);
> +
> +	n_written = yaffs_wr_file(obj, buf, ipos, n, 0);
> +
> +	yaffs_touch_super(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_file_write: %d(%x) bytes written",
> +		(unsigned)n, (unsigned)n);
> +
> +	if (n_written > 0) {
> +		ipos += n_written;
> +		*pos = ipos;
> +		if (ipos > inode->i_size) {
> +			inode->i_size = ipos;
> +			inode->i_blocks = (ipos + 511) >> 9;
> +
> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"yaffs_file_write size updated to %d bytes, %d blocks",
> +				ipos, (int)(inode->i_blocks));
> +		}

Same for this bit. What is yaffs lock protecting in the above piece of code?

> +	}
> +	yaffs_gross_unlock(dev);
> +	return (n_written == 0) && (n > 0) ? -ENOSPC : n_written;
> +}
> +
> +static int yaffs_write_end(struct file *filp, struct address_space *mapping,
> +			   loff_t pos, unsigned len, unsigned copied,
> +			   struct page *pg, void *fsdadata)
> +{
> +	int ret = 0;
> +	void *addr, *kva;
> +	uint32_t offset_into_page = pos & (PAGE_CACHE_SIZE - 1);
> +
> +	kva = kmap(pg);
> +	addr = kva + offset_into_page;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_write_end addr %p pos %x n_bytes %d",
> +		addr, (unsigned)pos, copied);
> +
> +	ret = yaffs_file_write(filp, addr, copied, &pos);
> +
> +	if (ret != copied) {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_write_end not same size ret %d  copied %d",
> +			ret, copied);
> +		SetPageError(pg);
> +	}
> +
> +	kunmap(pg);
> +
> +	yaffs_release_space(filp);
> +	unlock_page(pg);
> +	page_cache_release(pg);
> +	return ret;
> +}
> +
> +static int yaffs_statfs(struct dentry *dentry, struct kstatfs *buf)
> +{
> +	struct yaffs_dev *dev = yaffs_dentry_to_obj(dentry)->my_dev;
> +	struct super_block *sb = dentry->d_sb;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_statfs");
> +
> +	yaffs_gross_lock(dev);
> +
> +	buf->f_type = YAFFS_MAGIC;
> +	buf->f_bsize = sb->s_blocksize;
> +	buf->f_namelen = 255;

Looking at other filesystems suggests that this is already protected by
the vfs or does not require locking.

> +
> +	if (dev->data_bytes_per_chunk & (dev->data_bytes_per_chunk - 1)) {
> +		/* Do this if chunk size is not a power of 2 */
> +
> +		uint64_t bytes_in_dev;
> +		uint64_t bytes_free;
> +
> +		bytes_in_dev =
> +		    ((uint64_t)
> +		     ((dev->param.end_block - dev->param.start_block + 1))) *
> +		     ((uint64_t) (dev->param.chunks_per_block *
> +					   dev->data_bytes_per_chunk));
> +
> +		do_div(bytes_in_dev, sb->s_blocksize);
> +			/* bytes_in_dev becomes the number of blocks */
> +		buf->f_blocks = bytes_in_dev;
> +
> +		bytes_free = ((uint64_t) (yaffs_get_n_free_chunks(dev))) *
> +		    ((uint64_t) (dev->data_bytes_per_chunk));
> +
> +		do_div(bytes_free, sb->s_blocksize);
> +
> +		buf->f_bfree = bytes_free;
> +
> +	} else if (sb->s_blocksize > dev->data_bytes_per_chunk) {
> +
> +		buf->f_blocks =
> +		    (dev->param.end_block - dev->param.start_block + 1) *
> +		    dev->param.chunks_per_block /
> +		    (sb->s_blocksize / dev->data_bytes_per_chunk);
> +		buf->f_bfree =
> +		    yaffs_get_n_free_chunks(dev) /
> +		    (sb->s_blocksize / dev->data_bytes_per_chunk);
> +	} else {
> +		buf->f_blocks =
> +		    (dev->param.end_block - dev->param.start_block + 1) *
> +		    dev->param.chunks_per_block *
> +		    (dev->data_bytes_per_chunk / sb->s_blocksize);
> +
> +		buf->f_bfree =
> +		    yaffs_get_n_free_chunks(dev) *
> +		    (dev->data_bytes_per_chunk / sb->s_blocksize);
> +	}
> +
> +	buf->f_files = 0;
> +	buf->f_ffree = 0;
> +	buf->f_bavail = buf->f_bfree;

and this probably doesn't need to be protected either. Shuffle the lock
so that it is protecting just the parts it needs to.

> +
> +	yaffs_gross_unlock(dev);
> +	return 0;
> +}
> +
> +static void yaffs_flush_inodes(struct super_block *sb)
> +{
> +	struct inode *iptr;
> +	struct yaffs_obj *obj;
> +

Possibly you want a comment saying that this function is called with
gross lock held, since currently yaffs_flush_file requires gross lock to
be held. Better solution would be to fix the locking :-).

> +	list_for_each_entry(iptr, &sb->s_inodes, i_sb_list) {
> +		obj = yaffs_inode_to_obj(iptr);
> +		if (obj) {
> +			yaffs_trace(YAFFS_TRACE_OS,
> +				"flushing obj %d", obj->obj_id);
> +			yaffs_flush_file(obj, 1, 0);
> +		}
> +	}
> +}
> +
> +static void yaffs_flush_super(struct super_block *sb, int do_checkpoint)

This is also called with gross lock held. Comment?

> +{
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +
> +	if (!dev)
> +		return;
> +
> +	yaffs_flush_inodes(sb);
> +	yaffs_update_dirty_dirs(dev);
> +	yaffs_flush_whole_cache(dev);
> +	if (do_checkpoint)
> +		yaffs_checkpoint_save(dev);
> +}
> +
> +static unsigned yaffs_bg_gc_urgency(struct yaffs_dev *dev)
> +{
> +	unsigned erased_chunks =
> +	    dev->n_erased_blocks * dev->param.chunks_per_block;
> +	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
> +	unsigned scattered = 0;	/* Free chunks not in an erased block */
> +
> +	if (erased_chunks < dev->n_free_chunks)
> +		scattered = (dev->n_free_chunks - erased_chunks);
> +
> +	if (!context->bg_running)
> +		return 0;
> +	else if (scattered < (dev->param.chunks_per_block * 2))
> +		return 0;
> +	else if (erased_chunks > dev->n_free_chunks / 2)
> +		return 0;
> +	else if (erased_chunks > dev->n_free_chunks / 4)
> +		return 1;
> +	else
> +		return 2;
> +}
> +
> +static int yaffs_do_sync_fs(struct super_block *sb, int request_checkpoint)
> +{
> +
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +	unsigned int oneshot_checkpoint = (yaffs_auto_checkpoint & 4);
> +	unsigned gc_urgent = yaffs_bg_gc_urgency(dev);
> +	int do_checkpoint;
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
> +		"yaffs_do_sync_fs: gc-urgency %d %s %s%s",
> +		gc_urgent,
> +		sb->s_dirt ? "dirty" : "clean",
> +		request_checkpoint ? "checkpoint requested" : "no checkpoint",
> +		oneshot_checkpoint ? " one-shot" : "");
> +
> +	yaffs_gross_lock(dev);
> +	do_checkpoint = ((request_checkpoint && !gc_urgent) ||
> +			 oneshot_checkpoint) && !dev->is_checkpointed;
> +
> +	if (sb->s_dirt || do_checkpoint) {
> +		yaffs_flush_super(sb, !dev->is_checkpointed && do_checkpoint);
> +		sb->s_dirt = 0;
> +		if (oneshot_checkpoint)
> +			yaffs_auto_checkpoint &= ~4;
> +	}
> +	yaffs_gross_unlock(dev);
> +
> +	return 0;
> +}
> +
> +/*
> + * yaffs background thread functions .
> + * yaffs_bg_thread_fn() the thread function
> + * yaffs_bg_start() launches the background thread.
> + * yaffs_bg_stop() cleans up the background thread.
> + *
> + * NB:
> + * The thread should only run after the yaffs is initialised
> + * The thread should be stopped before yaffs is unmounted.
> + * The thread should not do any writing while the fs is in read only.
> + */
> +
> +void yaffs_background_waker(unsigned long data)
> +{
> +	wake_up_process((struct task_struct *)data);
> +}
> +
> +static int yaffs_bg_thread_fn(void *data)
> +{
> +	struct yaffs_dev *dev = (struct yaffs_dev *)data;
> +	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
> +	unsigned long now = jiffies;
> +	unsigned long next_dir_update = now;
> +	unsigned long next_gc = now;
> +	unsigned long expires;
> +	unsigned int urgency;
> +	int gc_result;
> +	struct timer_list timer;
> +
> +	yaffs_trace(YAFFS_TRACE_BACKGROUND,
> +		"yaffs_background starting for dev %p", (void *)dev);
> +
> +	set_freezable();
> +	while (context->bg_running) {
> +		yaffs_trace(YAFFS_TRACE_BACKGROUND, "yaffs_background");
> +
> +		if (kthread_should_stop())
> +			break;
> +
> +		if (try_to_freeze())
> +			continue;
> +
> +		yaffs_gross_lock(dev);
> +
> +		now = jiffies;
> +
> +		if (time_after(now, next_dir_update) && yaffs_bg_enable) {
> +			yaffs_update_dirty_dirs(dev);
> +			next_dir_update = now + HZ;
> +		}
> +
> +		if (time_after(now, next_gc) && yaffs_bg_enable) {
> +			if (!dev->is_checkpointed) {
> +				urgency = yaffs_bg_gc_urgency(dev);
> +				gc_result = yaffs_bg_gc(dev, urgency);
> +				if (urgency > 1)
> +					next_gc = now + HZ / 20 + 1;
> +				else if (urgency > 0)
> +					next_gc = now + HZ / 10 + 1;
> +				else
> +					next_gc = now + HZ * 2;
> +			} else	{
> +				/*
> +				 * gc not running so set to next_dir_update
> +				 * to cut down on wake ups
> +				 */
> +				next_gc = next_dir_update;
> +			}
> +		}
> +		yaffs_gross_unlock(dev);
> +		expires = next_dir_update;
> +		if (time_before(next_gc, expires))
> +			expires = next_gc;
> +		if (time_before(expires, now))
> +			expires = now + HZ;
> +
> +		init_timer_on_stack(&timer);
> +		timer.expires = expires + 1;
> +		timer.data = (unsigned long)current;
> +		timer.function = yaffs_background_waker;
> +
> +		set_current_state(TASK_INTERRUPTIBLE);
> +		add_timer(&timer);
> +		schedule();
> +		del_timer_sync(&timer);
> +	}
> +
> +	return 0;
> +}
> +
> +static int yaffs_bg_start(struct yaffs_dev *dev)
> +{

We hold the lock when calling this function too. This could possibly be
a garbage collector lock?

> +	int retval = 0;
> +	struct yaffs_linux_context *context = yaffs_dev_to_lc(dev);
> +
> +	if (dev->read_only)
> +		return -1;
> +
> +	context->bg_running = 1;
> +
> +	context->bg_thread = kthread_run(yaffs_bg_thread_fn,
> +					 (void *)dev, "yaffs-bg-%d",
> +					 context->mount_id);
> +
> +	if (IS_ERR(context->bg_thread)) {
> +		retval = PTR_ERR(context->bg_thread);
> +		context->bg_thread = NULL;
> +		context->bg_running = 0;
> +	}
> +	return retval;
> +}
> +
> +static void yaffs_bg_stop(struct yaffs_dev *dev)
> +{
> +	struct yaffs_linux_context *ctxt = yaffs_dev_to_lc(dev);
> +
> +	ctxt->bg_running = 0;

This is not called with gross lock held (as far as I can tell) so the
access on bg_running is potentially racy?

> +
> +	if (ctxt->bg_thread) {
> +		kthread_stop(ctxt->bg_thread);
> +		ctxt->bg_thread = NULL;
> +	}
> +}
> +
> +static void yaffs_write_super(struct super_block *sb)
> +{
> +	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 2);
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC | YAFFS_TRACE_BACKGROUND,
> +		"yaffs_write_super%s",
> +		request_checkpoint ? " checkpt" : "");
> +
> +	yaffs_do_sync_fs(sb, request_checkpoint);
> +
> +}
> +
> +static int yaffs_sync_fs(struct super_block *sb, int wait)
> +{
> +	unsigned request_checkpoint = (yaffs_auto_checkpoint >= 1);
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_SYNC,
> +		"yaffs_sync_fs%s", request_checkpoint ? " checkpt" : "");
> +
> +	yaffs_do_sync_fs(sb, request_checkpoint);
> +
> +	return 0;
> +}
> +
> +static LIST_HEAD(yaffs_context_list);
> +struct mutex yaffs_context_lock;

Make this static, and initialise it here?

> +
> +struct yaffs_options {
> +	int inband_tags;
> +	int skip_checkpoint_read;
> +	int skip_checkpoint_write;
> +	int no_cache;
> +	int tags_ecc_on;
> +	int tags_ecc_overridden;
> +	int lazy_loading_enabled;
> +	int lazy_loading_overridden;
> +	int empty_lost_and_found;
> +	int empty_lost_and_found_overridden;
> +};
> +
> +#define MAX_OPT_LEN 30
> +static int yaffs_parse_options(struct yaffs_options *options,
> +				const char *options_str)
> +{
> +	char cur_opt[MAX_OPT_LEN + 1];
> +	int p;
> +	int error = 0;
> +
> +	/* Parse through the options which is a comma seperated list */
> +
> +	while (options_str && *options_str && !error) {
> +		memset(cur_opt, 0, MAX_OPT_LEN + 1);
> +		p = 0;
> +
> +		while (*options_str == ',')
> +			options_str++;
> +
> +		while (*options_str && *options_str != ',') {
> +			if (p < MAX_OPT_LEN) {
> +				cur_opt[p] = *options_str;
> +				p++;
> +			}
> +			options_str++;
> +		}
> +
> +		if (!strcmp(cur_opt, "inband-tags")) {
> +			options->inband_tags = 1;
> +		} else if (!strcmp(cur_opt, "tags-ecc-off")) {
> +			options->tags_ecc_on = 0;
> +			options->tags_ecc_overridden = 1;
> +		} else if (!strcmp(cur_opt, "tags-ecc-on")) {
> +			options->tags_ecc_on = 1;
> +			options->tags_ecc_overridden = 1;
> +		} else if (!strcmp(cur_opt, "lazy-loading-off")) {
> +			options->lazy_loading_enabled = 0;
> +			options->lazy_loading_overridden = 1;
> +		} else if (!strcmp(cur_opt, "lazy-loading-on")) {
> +			options->lazy_loading_enabled = 1;
> +			options->lazy_loading_overridden = 1;
> +		} else if (!strcmp(cur_opt, "empty-lost-and-found-off")) {
> +			options->empty_lost_and_found = 0;
> +			options->empty_lost_and_found_overridden = 1;
> +		} else if (!strcmp(cur_opt, "empty-lost-and-found-on")) {
> +			options->empty_lost_and_found = 1;
> +			options->empty_lost_and_found_overridden = 1;
> +		} else if (!strcmp(cur_opt, "no-cache")) {
> +			options->no_cache = 1;
> +		} else if (!strcmp(cur_opt, "no-checkpoint-read")) {
> +			options->skip_checkpoint_read = 1;
> +		} else if (!strcmp(cur_opt, "no-checkpoint-write")) {
> +			options->skip_checkpoint_write = 1;
> +		} else if (!strcmp(cur_opt, "no-checkpoint")) {
> +			options->skip_checkpoint_read = 1;
> +			options->skip_checkpoint_write = 1;
> +		} else {
> +			printk(KERN_INFO "yaffs: Bad mount option \"%s\"\n",
> +			       cur_opt);
> +			error = 1;
> +		}
> +	}
> +	return error;
> +}
> +
> +static const struct address_space_operations yaffs_file_address_operations = {
> +	.readpage = yaffs_readpage,
> +	.writepage = yaffs_writepage,
> +	.write_begin = yaffs_write_begin,
> +	.write_end = yaffs_write_end,
> +};
> +
> +
> +
> +static const struct inode_operations yaffs_file_inode_operations = {
> +	.setattr = yaffs_setattr,
> +#ifdef CONFIG_YAFFS_XATTR
> +	.setxattr = yaffs_setxattr,
> +	.getxattr = yaffs_getxattr,
> +	.listxattr = yaffs_listxattr,
> +	.removexattr = yaffs_removexattr,
> +#endif
> +};
> +
> +static const struct inode_operations yaffs_symlink_inode_operations = {
> +	.readlink = yaffs_readlink,
> +	.follow_link = yaffs_follow_link,
> +	.put_link = yaffs_put_link,
> +	.setattr = yaffs_setattr,
> +#ifdef CONFIG_YAFFS_XATTR
> +	.setxattr = yaffs_setxattr,
> +	.getxattr = yaffs_getxattr,
> +	.listxattr = yaffs_listxattr,
> +	.removexattr = yaffs_removexattr,
> +#endif
> +};

Nitpick. Tab delimit struct initialisations.

> +
> +static void yaffs_fill_inode_from_obj(struct inode *inode,
> +				      struct yaffs_obj *obj)
> +{
> +	u32 mode;
> +
> +	if (!inode || !obj)  {
> +		yaffs_trace(YAFFS_TRACE_OS,
> +			"yaffs_fill_inode invalid parameters");
> +		return;
> +	}
> +
> +	/* Check mode against the variant type
> +	 * and attempt to repair if broken. */
> +	mode = obj->yst_mode;
> +
> +	switch (obj->variant_type) {
> +	case YAFFS_OBJECT_TYPE_FILE:
> +		if (!S_ISREG(mode)) {
> +			obj->yst_mode &= ~S_IFMT;
> +			obj->yst_mode |= S_IFREG;
> +		}
> +		break;
> +	case YAFFS_OBJECT_TYPE_SYMLINK:
> +		if (!S_ISLNK(mode)) {
> +			obj->yst_mode &= ~S_IFMT;
> +			obj->yst_mode |= S_IFLNK;
> +		}
> +		break;
> +	case YAFFS_OBJECT_TYPE_DIRECTORY:
> +		if (!S_ISDIR(mode)) {
> +			obj->yst_mode &= ~S_IFMT;
> +			obj->yst_mode |= S_IFDIR;
> +		}
> +		break;
> +	case YAFFS_OBJECT_TYPE_UNKNOWN:
> +	case YAFFS_OBJECT_TYPE_HARDLINK:
> +	case YAFFS_OBJECT_TYPE_SPECIAL:
> +	default:
> +		/* TODO? */
> +		break;
> +	}
> +
> +	inode->i_flags |= S_NOATIME;
> +	inode->i_ino = obj->obj_id;
> +	inode->i_mode = obj->yst_mode;
> +	inode->i_uid = obj->yst_uid;
> +	inode->i_gid = obj->yst_gid;
> +
> +	inode->i_rdev = old_decode_dev(obj->yst_rdev);
> +
> +	inode->i_atime.tv_sec = (time_t) (obj->yst_atime);
> +	inode->i_atime.tv_nsec = 0;
> +	inode->i_mtime.tv_sec = (time_t) obj->yst_mtime;
> +	inode->i_mtime.tv_nsec = 0;
> +	inode->i_ctime.tv_sec = (time_t) obj->yst_ctime;
> +	inode->i_ctime.tv_nsec = 0;
> +	inode->i_size = yaffs_get_obj_length(obj);
> +	inode->i_blocks = (inode->i_size + 511) >> 9;
> +	inode->i_nlink = yaffs_get_obj_link_count(obj);
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_fill_inode mode %x uid %d gid %d size %d count %d",
> +		inode->i_mode, inode->i_uid, inode->i_gid,
> +		(int)inode->i_size, atomic_read(&inode->i_count));
> +
> +	switch (obj->yst_mode & S_IFMT) {
> +	default:	/* fifo, device or socket */
> +		init_special_inode(inode, obj->yst_mode,
> +				   old_decode_dev(obj->yst_rdev));
> +		break;
> +	case S_IFREG:	/* file */
> +		inode->i_op = &yaffs_file_inode_operations;
> +		inode->i_fop = &yaffs_file_operations;
> +		inode->i_mapping->a_ops = &yaffs_file_address_operations;
> +		break;
> +	case S_IFDIR:	/* directory */
> +		inode->i_op = &yaffs_dir_inode_operations;
> +		inode->i_fop = &yaffs_dir_operations;
> +		break;
> +	case S_IFLNK:	/* symlink */
> +		inode->i_op = &yaffs_symlink_inode_operations;
> +		break;
> +	}
> +
> +	yaffs_inode_to_obj_lv(inode) = obj;
> +	obj->my_inode = inode;
> +}
> +
> +static void yaffs_put_super(struct super_block *sb)
> +{
> +	struct yaffs_dev *dev = yaffs_super_to_dev(sb);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_put_super");
> +
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
> +		"Shutting down yaffs background thread");
> +	yaffs_bg_stop(dev);
> +	yaffs_trace(YAFFS_TRACE_OS | YAFFS_TRACE_BACKGROUND,
> +		"yaffs background thread shut down");
> +
> +	yaffs_gross_lock(dev);
> +
> +	yaffs_flush_super(sb, 1);
> +
> +	if (yaffs_dev_to_lc(dev)->put_super_fn)
> +		yaffs_dev_to_lc(dev)->put_super_fn(sb);
> +
> +	yaffs_deinitialise(dev);
> +
> +	yaffs_gross_unlock(dev);
> +	mutex_lock(&yaffs_context_lock);
> +	list_del_init(&(yaffs_dev_to_lc(dev)->context_list));
> +	mutex_unlock(&yaffs_context_lock);
> +
> +	if (yaffs_dev_to_lc(dev)->spare_buffer) {
> +		kfree(yaffs_dev_to_lc(dev)->spare_buffer);
> +		yaffs_dev_to_lc(dev)->spare_buffer = NULL;
> +	}
> +
> +	kfree(dev);
> +}
> +
> +static void yaffs_mtd_put_super(struct super_block *sb)
> +{
> +	struct mtd_info *mtd = yaffs_dev_to_mtd(yaffs_super_to_dev(sb));
> +
> +	if (mtd->sync)
> +		mtd->sync(mtd);
> +
> +	put_mtd_device(mtd);
> +}
> +
> +static const struct super_operations yaffs_super_ops = {
> +	.statfs = yaffs_statfs,
> +	.put_super = yaffs_put_super,
> +	.evict_inode = yaffs_evict_inode,
> +	.sync_fs = yaffs_sync_fs,
> +	.write_super = yaffs_write_super,
> +};
> +
> +static struct super_block *yaffs_internal_read_super(int yaffs_version,
> +						     struct super_block *sb,
> +						     void *data, int silent)
> +{
> +	int n_blocks;
> +	struct inode *inode = NULL;
> +	struct dentry *root;
> +	struct yaffs_dev *dev = 0;
> +	char devname_buf[BDEVNAME_SIZE + 1];
> +	struct mtd_info *mtd;
> +	int err;
> +	char *data_str = (char *)data;
> +	struct yaffs_linux_context *context = NULL;
> +	struct yaffs_param *param;
> +	int read_only = 0;
> +	struct yaffs_options options;
> +	unsigned mount_id;
> +	int found;
> +	struct yaffs_linux_context *context_iterator;
> +	struct list_head *l;
> +
> +	if (!sb) {
> +		printk(KERN_INFO "yaffs: sb is NULL\n");
> +		return NULL;
> +	}
> +
> +	sb->s_magic = YAFFS_MAGIC;
> +	sb->s_op = &yaffs_super_ops;
> +	sb->s_flags |= MS_NOATIME;
> +
> +	read_only = ((sb->s_flags & MS_RDONLY) != 0);
> +
> +	sb->s_export_op = &yaffs_export_ops;
> +
> +	if (!sb->s_dev)
> +		printk(KERN_INFO "yaffs: sb->s_dev is NULL\n");
> +	else if (!yaffs_devname(sb, devname_buf))
> +		printk(KERN_INFO "yaffs: devname is NULL\n");
> +	else
> +		printk(KERN_INFO "yaffs: dev is %d name is \"%s\" %s\n",
> +		       sb->s_dev,
> +		       yaffs_devname(sb, devname_buf), read_only ? "ro" : "rw");
> +
> +	if (!data_str)
> +		data_str = "";
> +
> +	printk(KERN_INFO "yaffs: passed flags \"%s\"\n", data_str);
> +
> +	memset(&options, 0, sizeof(options));
> +
> +	if (yaffs_parse_options(&options, data_str))
> +		/* Option parsing failed */
> +		return NULL;
> +
> +	sb->s_blocksize = PAGE_CACHE_SIZE;
> +	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_read_super: Using yaffs%d", yaffs_version);
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_read_super: block size %d", (int)(sb->s_blocksize));
> +
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"Attempting MTD mount of %u.%u,\"%s\"",
> +		MAJOR(sb->s_dev), MINOR(sb->s_dev),
> +		yaffs_devname(sb, devname_buf));
> +
> +	/* Check it's an mtd device..... */
> +	if (MAJOR(sb->s_dev) != MTD_BLOCK_MAJOR)
> +		return NULL;	/* This isn't an mtd device */
> +
> +	/* Get the device */
> +	mtd = get_mtd_device(NULL, MINOR(sb->s_dev));
> +	if (!mtd) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"MTD device #%u doesn't appear to exist",
> +			MINOR(sb->s_dev));
> +		return NULL;
> +	}
> +	/* Check it's NAND */
> +	if (mtd->type != MTD_NANDFLASH) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"MTD device is not NAND it's type %d",
> +			mtd->type);
> +		return NULL;
> +	}
> +
> +	yaffs_trace(YAFFS_TRACE_OS, " erase %p", mtd->erase);
> +	yaffs_trace(YAFFS_TRACE_OS, " read %p", mtd->read);
> +	yaffs_trace(YAFFS_TRACE_OS, " write %p", mtd->write);
> +	yaffs_trace(YAFFS_TRACE_OS, " readoob %p", mtd->read_oob);
> +	yaffs_trace(YAFFS_TRACE_OS, " writeoob %p", mtd->write_oob);
> +	yaffs_trace(YAFFS_TRACE_OS, " block_isbad %p", mtd->block_isbad);
> +	yaffs_trace(YAFFS_TRACE_OS, " block_markbad %p", mtd->block_markbad);
> +	yaffs_trace(YAFFS_TRACE_OS, " writesize %d", mtd->writesize);
> +	yaffs_trace(YAFFS_TRACE_OS, " oobsize %d", mtd->oobsize);
> +	yaffs_trace(YAFFS_TRACE_OS, " erasesize %d", mtd->erasesize);
> +	yaffs_trace(YAFFS_TRACE_OS, " size %lld", mtd->size);
> +
> +#ifdef CONFIG_YAFFS_AUTO_YAFFS2
> +
> +	if (yaffs_version == 1 && mtd->writesize >= 2048) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs2");
> +		yaffs_version = 2;
> +	}
> +
> +	/* Added NCB 26/5/2006 for completeness */
> +	if (yaffs_version == 2 && !options.inband_tags &&
> +		mtd->writesize == 512) {
> +		yaffs_trace(YAFFS_TRACE_ALWAYS, "auto selecting yaffs1");
> +		yaffs_version = 1;
> +	}
> +#endif
> +
> +	if (yaffs_version == 2) {
> +		/* Check for version 2 style functions */
> +		if (!mtd->erase ||
> +		    !mtd->block_isbad ||
> +		    !mtd->block_markbad ||
> +		    !mtd->read ||
> +		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not support required functions");
> +			return NULL;
> +		}
> +
> +		if ((mtd->writesize < YAFFS_MIN_YAFFS2_CHUNK_SIZE ||
> +		     mtd->oobsize < YAFFS_MIN_YAFFS2_SPARE_SIZE) &&
> +		    !options.inband_tags) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not have the right page sizes");
> +			return NULL;
> +		}
> +	} else {
> +		/* Check for V1 style functions */
> +		if (!mtd->erase ||
> +		    !mtd->read ||
> +		    !mtd->write || !mtd->read_oob || !mtd->write_oob) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not support required functions");
> +			return NULL;
> +		}
> +
> +		if (mtd->writesize < YAFFS_BYTES_PER_CHUNK ||
> +		    mtd->oobsize != YAFFS_BYTES_PER_SPARE) {
> +			yaffs_trace(YAFFS_TRACE_ALWAYS,
> +				"MTD device does not support have the right page sizes");
> +			return NULL;
> +		}
> +	}
> +
> +	/* OK, so if we got here, we have an MTD that's NAND and looks
> +	 * like it has the right capabilities
> +	 * Set the struct yaffs_dev up for mtd
> +	 */
> +
> +	if (!read_only && !(mtd->flags & MTD_WRITEABLE)) {
> +		read_only = 1;
> +		printk(KERN_INFO
> +		       "yaffs: mtd is read only, setting superblock read only");
> +		sb->s_flags |= MS_RDONLY;
> +	}
> +
> +	dev = kmalloc(sizeof(struct yaffs_dev), GFP_KERNEL);
> +	context = kmalloc(sizeof(struct yaffs_linux_context), GFP_KERNEL);
> +
> +	if (!dev || !context) {
> +		kfree(dev);
> +		kfree(context);
> +		dev = NULL;
> +		context = NULL;

Don't need the NULL assignments. Should also bail here rather than
testing just !dev below.

> +	}
> +
> +	if (!dev) {
> +		/* Deep shit could not allocate device structure */
> +		yaffs_trace(YAFFS_TRACE_ALWAYS,
> +			"yaffs_read_super failed trying to allocate yaffs_dev");
> +		return NULL;
> +	}
> +	memset(dev, 0, sizeof(struct yaffs_dev));
> +	param = &(dev->param);
> +
> +	memset(context, 0, sizeof(struct yaffs_linux_context));

We will explode here if context allocation failed above.

> +	dev->os_context = context;
> +	INIT_LIST_HEAD(&(context->context_list));
> +	context->dev = dev;
> +	context->super = sb;
> +
> +	dev->read_only = read_only;
> +
> +	sb->s_fs_info = dev;
> +
> +	dev->driver_context = mtd;
> +	param->name = mtd->name;
> +
> +	/* Set up the memory size parameters.... */
> +
> +	n_blocks =
> +	    YCALCBLOCKS(mtd->size,
> +			(YAFFS_CHUNKS_PER_BLOCK * YAFFS_BYTES_PER_CHUNK));
> +
> +	param->start_block = 0;
> +	param->end_block = n_blocks - 1;
> +	param->chunks_per_block = YAFFS_CHUNKS_PER_BLOCK;
> +	param->total_bytes_per_chunk = YAFFS_BYTES_PER_CHUNK;
> +	param->n_reserved_blocks = 5;
> +	param->n_caches = (options.no_cache) ? 0 : 10;
> +	param->inband_tags = options.inband_tags;
> +
> +#ifdef CONFIG_YAFFS_DISABLE_LAZY_LOAD

Non-existent Kconfig option

> +	param->disable_lazy_load = 1;
> +#endif
> +#ifdef CONFIG_YAFFS_XATTR
> +	param->enable_xattr = 1;
> +#endif
> +	if (options.lazy_loading_overridden)
> +		param->disable_lazy_load = !options.lazy_loading_enabled;
> +
> +#ifdef CONFIG_YAFFS_DISABLE_TAGS_ECC
> +	param->no_tags_ecc = 1;
> +#endif
> +
> +#ifdef CONFIG_YAFFS_DISABLE_BACKGROUND

This ifdef block is empty. Change to ifndef.

> +#else
> +	param->defered_dir_update = 1;
> +#endif
> +
> +	if (options.tags_ecc_overridden)
> +		param->no_tags_ecc = !options.tags_ecc_on;
> +
> +#ifdef CONFIG_YAFFS_EMPTY_LOST_AND_FOUND
> +	param->empty_lost_n_found = 1;
> +#endif
> +
> +#ifdef CONFIG_YAFFS_DISABLE_BLOCK_REFRESHING
> +	param->refresh_period = 0;
> +#else
> +	param->refresh_period = 500;
> +#endif
> +
> +#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
> +	param->always_check_erased = 1;
> +#endif
> +
> +	if (options.empty_lost_and_found_overridden)
> +		param->empty_lost_n_found = options.empty_lost_and_found;
> +
> +	/* ... and the functions. */
> +	if (yaffs_version == 2) {
> +		param->write_chunk_tags_fn = nandmtd2_write_chunk_tags;
> +		param->read_chunk_tags_fn = nandmtd2_read_chunk_tags;
> +		param->bad_block_fn = nandmtd2_mark_block_bad;
> +		param->query_block_fn = nandmtd2_query_block;
> +		yaffs_dev_to_lc(dev)->spare_buffer =
> +				kmalloc(mtd->oobsize, GFP_NOFS);
> +		param->is_yaffs2 = 1;
> +		param->total_bytes_per_chunk = mtd->writesize;
> +		param->chunks_per_block = mtd->erasesize / mtd->writesize;
> +		n_blocks = YCALCBLOCKS(mtd->size, mtd->erasesize);
> +
> +		param->start_block = 0;
> +		param->end_block = n_blocks - 1;
> +	} else {
> +		/* use the MTD interface in yaffs_mtdif1.c */
> +		param->write_chunk_tags_fn = nandmtd1_write_chunk_tags;
> +		param->read_chunk_tags_fn = nandmtd1_read_chunk_tags;
> +		param->bad_block_fn = nandmtd1_mark_block_bad;
> +		param->query_block_fn = nandmtd1_query_block;
> +		param->is_yaffs2 = 0;
> +	}
> +	/* ... and common functions */
> +	param->erase_fn = nandmtd_erase_block;
> +	param->initialise_flash_fn = nandmtd_initialise;
> +
> +	yaffs_dev_to_lc(dev)->put_super_fn = yaffs_mtd_put_super;
> +
> +	param->sb_dirty_fn = yaffs_touch_super;
> +	param->gc_control = yaffs_gc_control_callback;
> +
> +	yaffs_dev_to_lc(dev)->super = sb;
> +
> +#ifndef CONFIG_YAFFS_DOES_ECC
> +	param->use_nand_ecc = 1;
> +#endif
> +
> +	param->skip_checkpt_rd = options.skip_checkpoint_read;
> +	param->skip_checkpt_wr = options.skip_checkpoint_write;
> +
> +	mutex_lock(&yaffs_context_lock);
> +	/* Get a mount id */
> +	for (mount_id = 0, found = 0; !found; mount_id++) {
> +		found = 1;
> +		list_for_each(l, &yaffs_context_list) {
> +			context_iterator =
> +				list_entry(l, struct yaffs_linux_context,
> +					context_list);

list_for_each_entry

> +			if (context_iterator->mount_id == mount_id)
> +				found = 0;
> +		}
> +	}
> +	context->mount_id = mount_id;
> +
> +	list_add_tail(&(yaffs_dev_to_lc(dev)->context_list),
> +		      &yaffs_context_list);
> +	mutex_unlock(&yaffs_context_lock);
> +
> +	/* Directory search handling... */
> +	INIT_LIST_HEAD(&(yaffs_dev_to_lc(dev)->search_contexts));
> +	param->remove_obj_fn = yaffs_remove_obj_callback;
> +
> +	mutex_init(&(yaffs_dev_to_lc(dev)->gross_lock));
> +
> +	yaffs_gross_lock(dev);

Can we be in parallel here? We are initialising the filesystem.

> +
> +	err = yaffs_guts_initialise(dev);
> +
> +	yaffs_trace(YAFFS_TRACE_OS,
> +		"yaffs_read_super: guts initialised %s",
> +		(err == YAFFS_OK) ? "OK" : "FAILED");
> +
> +	if (err == YAFFS_OK)
> +		yaffs_bg_start(dev);
> +
> +	if (!context->bg_thread)
> +		param->defered_dir_update = 0;
> +
> +	/* Release lock before yaffs_get_inode() */
> +	yaffs_gross_unlock(dev);
> +
> +	/* Create root inode */
> +	if (err == YAFFS_OK)
> +		inode = yaffs_get_inode(sb, S_IFDIR | 0755, 0, yaffs_root(dev));
> +
> +	if (!inode)
> +		return NULL;
> +
> +	inode->i_op = &yaffs_dir_inode_operations;
> +	inode->i_fop = &yaffs_dir_operations;
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: got root inode");
> +
> +	root = d_alloc_root(inode);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: d_alloc_root done");
> +
> +	if (!root) {
> +		iput(inode);
> +		return NULL;
> +	}
> +	sb->s_root = root;
> +	sb->s_dirt = !dev->is_checkpointed;
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"yaffs_read_super: is_checkpointed %d",
> +		dev->is_checkpointed);
> +
> +	yaffs_trace(YAFFS_TRACE_OS, "yaffs_read_super: done");
> +	return sb;
> +}
> +
> +static int yaffs_internal_read_super_mtd(struct super_block *sb, void *data,
> +					 int silent)
> +{
> +	return yaffs_internal_read_super(1, sb, data, silent) ? 0 : -EINVAL;
> +}
> +
> +static int yaffs_read_super(struct file_system_type *fs,
> +			    int flags, const char *dev_name,
> +			    void *data, struct vfsmount *mnt)
> +{
> +
> +	return get_sb_bdev(fs, flags, dev_name, data,
> +			   yaffs_internal_read_super_mtd, mnt);
> +}
> +
> +static struct file_system_type yaffs_fs_type = {
> +	.owner = THIS_MODULE,
> +	.name = "yaffs",
> +	.get_sb = yaffs_read_super,
> +	.kill_sb = kill_block_super,
> +	.fs_flags = FS_REQUIRES_DEV,
> +};
> +
> +#ifdef CONFIG_YAFFS_YAFFS2
> +
> +static int yaffs2_internal_read_super_mtd(struct super_block *sb, void *data,
> +					  int silent)
> +{
> +	return yaffs_internal_read_super(2, sb, data, silent) ? 0 : -EINVAL;
> +}
> +
> +static int yaffs2_read_super(struct file_system_type *fs,
> +			     int flags, const char *dev_name, void *data,
> +			     struct vfsmount *mnt)
> +{
> +	return get_sb_bdev(fs, flags, dev_name, data,
> +			   yaffs2_internal_read_super_mtd, mnt);
> +}
> +
> +static struct file_system_type yaffs2_fs_type = {
> +	.owner = THIS_MODULE,
> +	.name = "yaffs2",
> +	.get_sb = yaffs2_read_super,
> +	.kill_sb = kill_block_super,
> +	.fs_flags = FS_REQUIRES_DEV,
> +};
> +#endif /* CONFIG_YAFFS_YAFFS2 */
> +
> +static struct proc_dir_entry *my_proc_entry;
> +
> +static char *yaffs_dump_dev_part0(char *buf, struct yaffs_dev *dev)
> +{
> +	struct yaffs_param *param = &dev->param;
> +
> +	buf += sprintf(buf, "start_block........... %d\n", param->start_block);
> +	buf += sprintf(buf, "end_block............. %d\n", param->end_block);
> +	buf += sprintf(buf, "total_bytes_per_chunk. %d\n",
> +			param->total_bytes_per_chunk);
> +	buf += sprintf(buf, "use_nand_ecc.......... %d\n",
> +			param->use_nand_ecc);
> +	buf += sprintf(buf, "no_tags_ecc........... %d\n", param->no_tags_ecc);
> +	buf += sprintf(buf, "is_yaffs2............. %d\n", param->is_yaffs2);
> +	buf += sprintf(buf, "inband_tags........... %d\n", param->inband_tags);
> +	buf += sprintf(buf, "empty_lost_n_found.... %d\n",
> +			param->empty_lost_n_found);
> +	buf += sprintf(buf, "disable_lazy_load..... %d\n",
> +			param->disable_lazy_load);
> +	buf += sprintf(buf, "refresh_period........ %d\n",
> +			param->refresh_period);
> +	buf += sprintf(buf, "n_caches.............. %d\n", param->n_caches);
> +	buf += sprintf(buf, "n_reserved_blocks..... %d\n",
> +			param->n_reserved_blocks);
> +	buf += sprintf(buf, "always_check_erased... %d\n",
> +			param->always_check_erased);
> +
> +	return buf;
> +}
> +
> +static char *yaffs_dump_dev_part1(char *buf, struct yaffs_dev *dev)
> +{
> +	buf +=
> +	    sprintf(buf, "data_bytes_per_chunk.. %d\n",
> +		    dev->data_bytes_per_chunk);
> +	buf += sprintf(buf, "chunk_grp_bits........ %d\n", dev->chunk_grp_bits);
> +	buf += sprintf(buf, "chunk_grp_size........ %d\n", dev->chunk_grp_size);
> +	buf +=
> +	    sprintf(buf, "n_erased_blocks....... %d\n", dev->n_erased_blocks);
> +	buf +=
> +	    sprintf(buf, "blocks_in_checkpt..... %d\n", dev->blocks_in_checkpt);
> +	buf += sprintf(buf, "\n");
> +	buf += sprintf(buf, "n_tnodes.............. %d\n", dev->n_tnodes);
> +	buf += sprintf(buf, "n_obj................. %d\n", dev->n_obj);
> +	buf += sprintf(buf, "n_free_chunks......... %d\n", dev->n_free_chunks);
> +	buf += sprintf(buf, "\n");
> +	buf += sprintf(buf, "n_page_writes......... %u\n", dev->n_page_writes);
> +	buf += sprintf(buf, "n_page_reads.......... %u\n", dev->n_page_reads);
> +	buf += sprintf(buf, "n_erasures............ %u\n", dev->n_erasures);
> +	buf += sprintf(buf, "n_gc_copies........... %u\n", dev->n_gc_copies);
> +	buf += sprintf(buf, "all_gcs............... %u\n", dev->all_gcs);
> +	buf +=
> +	    sprintf(buf, "passive_gc_count...... %u\n", dev->passive_gc_count);
> +	buf +=
> +	    sprintf(buf, "oldest_dirty_gc_count. %u\n",
> +		    dev->oldest_dirty_gc_count);
> +	buf += sprintf(buf, "n_gc_blocks........... %u\n", dev->n_gc_blocks);
> +	buf += sprintf(buf, "bg_gcs................ %u\n", dev->bg_gcs);
> +	buf +=
> +	    sprintf(buf, "n_retired_writes...... %u\n", dev->n_retired_writes);
> +	buf +=
> +	    sprintf(buf, "n_retired_blocks...... %u\n", dev->n_retired_blocks);
> +	buf += sprintf(buf, "n_ecc_fixed........... %u\n", dev->n_ecc_fixed);
> +	buf += sprintf(buf, "n_ecc_unfixed......... %u\n", dev->n_ecc_unfixed);
> +	buf +=
> +	    sprintf(buf, "n_tags_ecc_fixed...... %u\n", dev->n_tags_ecc_fixed);
> +	buf +=
> +	    sprintf(buf, "n_tags_ecc_unfixed.... %u\n",
> +		    dev->n_tags_ecc_unfixed);
> +	buf += sprintf(buf, "cache_hits............ %u\n", dev->cache_hits);
> +	buf +=
> +	    sprintf(buf, "n_deleted_files....... %u\n", dev->n_deleted_files);
> +	buf +=
> +	    sprintf(buf, "n_unlinked_files...... %u\n", dev->n_unlinked_files);
> +	buf += sprintf(buf, "refresh_count......... %u\n", dev->refresh_count);
> +	buf += sprintf(buf, "n_bg_deletions........ %u\n", dev->n_bg_deletions);
> +
> +	return buf;
> +}
> +
> +static int yaffs_proc_read(char *page,
> +			   char **start,
> +			   off_t offset, int count, int *eof, void *data)
> +{
> +	struct list_head *item;
> +	char *buf = page;
> +	int step = offset;
> +	int n = 0;
> +
> +	/* Get proc_file_read() to step 'offset' by one on each sucessive call.
> +	 * We use 'offset' (*ppos) to indicate where we are in dev_list.
> +	 * This also assumes the user has posted a read buffer large
> +	 * enough to hold the complete output; but that's life in /proc.
> +	 */
> +
> +	*(int *)start = 1;

Ick.

> +
> +	/* Print header first */
> +	if (step == 0)
> +		buf += sprintf(buf, "YAFFS built:" __DATE__ " " __TIME__ "\n");
> +	else if (step == 1)
> +		buf += sprintf(buf, "\n");
> +	else {
> +		step -= 2;
> +
> +		mutex_lock(&yaffs_context_lock);
> +
> +		/* Locate and print the Nth entry.
> +		 * Order N-squared but N is small. */
> +		list_for_each(item, &yaffs_context_list) {
> +			struct yaffs_linux_context *dc =
> +			    list_entry(item, struct yaffs_linux_context,
> +				       context_list);

list_for_each_entry

> +			struct yaffs_dev *dev = dc->dev;
> +
> +			if (n < (step & ~1)) {
> +				n += 2;
> +				continue;
> +			}
> +			if ((step & 1) == 0) {
> +				buf +=
> +				    sprintf(buf, "\nDevice %d \"%s\"\n", n,
> +					    dev->param.name);
> +				buf = yaffs_dump_dev_part0(buf, dev);
> +			} else {
> +				buf = yaffs_dump_dev_part1(buf, dev);
> +			}
> +
> +			break;
> +		}
> +		mutex_unlock(&yaffs_context_lock);
> +	}
> +
> +	return buf - page < count ? buf - page : count;
> +}
> +
> +
> +/**
> + * Set the verbosity of the warnings and error messages.
> + *
> + * Note that the names can only be a..z or _ with the current code.
> + */
> +
> +static struct {
> +	char *mask_name;
> +	unsigned mask_bitfield;
> +} mask_flags[] = {
> +	{"allocate", YAFFS_TRACE_ALLOCATE},
> +	{"always", YAFFS_TRACE_ALWAYS},
> +	{"background", YAFFS_TRACE_BACKGROUND},
> +	{"bad_blocks", YAFFS_TRACE_BAD_BLOCKS},
> +	{"buffers", YAFFS_TRACE_BUFFERS},
> +	{"bug", YAFFS_TRACE_BUG},
> +	{"checkpt", YAFFS_TRACE_CHECKPOINT},
> +	{"deletion", YAFFS_TRACE_DELETION},
> +	{"erase", YAFFS_TRACE_ERASE},
> +	{"error", YAFFS_TRACE_ERROR},
> +	{"gc_detail", YAFFS_TRACE_GC_DETAIL},
> +	{"gc", YAFFS_TRACE_GC},
> +	{"lock", YAFFS_TRACE_LOCK},
> +	{"mtd", YAFFS_TRACE_MTD},
> +	{"nandaccess", YAFFS_TRACE_NANDACCESS},
> +	{"os", YAFFS_TRACE_OS},
> +	{"scan_debug", YAFFS_TRACE_SCAN_DEBUG},
> +	{"scan", YAFFS_TRACE_SCAN},
> +	{"mount", YAFFS_TRACE_MOUNT},
> +	{"tracing", YAFFS_TRACE_TRACING},
> +	{"sync", YAFFS_TRACE_SYNC},
> +	{"write", YAFFS_TRACE_WRITE},
> +	{"verify", YAFFS_TRACE_VERIFY},
> +	{"verify_nand", YAFFS_TRACE_VERIFY_NAND},
> +	{"verify_full", YAFFS_TRACE_VERIFY_FULL},
> +	{"verify_all", YAFFS_TRACE_VERIFY_ALL},
> +	{"all", 0xffffffff},
> +	{"none", 0},
> +	{NULL, 0},

Tab delimit to make more readable.

> +};
> +
> +#define MAX_MASK_NAME_LENGTH 40
> +static int yaffs_proc_write_trace_options(struct file *file, const char *buf,
> +					  unsigned long count, void *data)
> +{
> +	unsigned rg = 0, mask_bitfield;
> +	char *end;
> +	char *mask_name;
> +	const char *x;
> +	char substring[MAX_MASK_NAME_LENGTH + 1];
> +	int i;
> +	int done = 0;
> +	int add, len = 0;
> +	int pos = 0;
> +
> +	rg = yaffs_trace_mask;
> +
> +	while (!done && (pos < count)) {
> +		done = 1;
> +		while ((pos < count) && isspace(buf[pos]))
> +			pos++;
> +
> +		switch (buf[pos]) {
> +		case '+':
> +		case '-':
> +		case '=':
> +			add = buf[pos];
> +			pos++;
> +			break;
> +
> +		default:
> +			add = ' ';
> +			break;
> +		}
> +		mask_name = NULL;
> +
> +		mask_bitfield = simple_strtoul(buf + pos, &end, 0);
> +
> +		if (end > buf + pos) {
> +			mask_name = "numeral";
> +			len = end - (buf + pos);
> +			pos += len;
> +			done = 0;
> +		} else {
> +			for (x = buf + pos, i = 0;
> +			     (*x == '_' || (*x >= 'a' && *x <= 'z')) &&
> +			     i < MAX_MASK_NAME_LENGTH; x++, i++, pos++)
> +				substring[i] = *x;
> +			substring[i] = '\0';
> +
> +			for (i = 0; mask_flags[i].mask_name != NULL; i++) {
> +				if (strcmp(substring, mask_flags[i].mask_name)
> +				    == 0) {
> +					mask_name = mask_flags[i].mask_name;
> +					mask_bitfield =
> +					    mask_flags[i].mask_bitfield;
> +					done = 0;
> +					break;
> +				}
> +			}
> +		}
> +
> +		if (mask_name != NULL) {
> +			done = 0;
> +			switch (add) {
> +			case '-':
> +				rg &= ~mask_bitfield;
> +				break;
> +			case '+':
> +				rg |= mask_bitfield;
> +				break;
> +			case '=':
> +				rg = mask_bitfield;
> +				break;
> +			default:
> +				rg |= mask_bitfield;
> +				break;
> +			}
> +		}
> +	}
> +
> +	yaffs_trace_mask = rg | YAFFS_TRACE_ALWAYS;
> +
> +	printk(KERN_DEBUG "new trace = 0x%08X\n", yaffs_trace_mask);
> +
> +	if (rg & YAFFS_TRACE_ALWAYS) {
> +		for (i = 0; mask_flags[i].mask_name != NULL; i++) {
> +			char flag;
> +			flag = ((rg & mask_flags[i].mask_bitfield) ==
> +				mask_flags[i].mask_bitfield) ? '+' : '-';
> +			printk(KERN_DEBUG "%c%s\n", flag,
> +			       mask_flags[i].mask_name);
> +		}
> +	}
> +
> +	return count;
> +}
> +
> +static int yaffs_proc_write(struct file *file, const char *buf,
> +			    unsigned long count, void *data)
> +{
> +	return yaffs_proc_write_trace_options(file, buf, count, data);
> +}
> +
> +/* Stuff to handle installation of file systems */
> +struct file_system_to_install {
> +	struct file_system_type *fst;
> +	int installed;
> +};
> +
> +static struct file_system_to_install fs_to_install[] = {
> +	{&yaffs_fs_type, 0},
> +	{&yaffs2_fs_type, 0},
> +	{NULL, 0}
> +};
> +
> +static int __init init_yaffs_fs(void)
> +{
> +	int error = 0;
> +	struct file_system_to_install *fsinst;
> +
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"yaffs built " __DATE__ " " __TIME__ " Installing.");
> +
> +#ifdef CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"\n\nYAFFS-WARNING CONFIG_YAFFS_ALWAYS_CHECK_CHUNK_ERASED selected.\n\n\n");
> +#endif
> +
> +	mutex_init(&yaffs_context_lock);
> +
> +	/* Install the proc_fs entries */
> +	my_proc_entry = create_proc_entry("yaffs",
> +					  S_IRUGO | S_IFREG, NULL);
> +
> +	if (my_proc_entry) {
> +		my_proc_entry->write_proc = yaffs_proc_write;
> +		my_proc_entry->read_proc = yaffs_proc_read;
> +		my_proc_entry->data = NULL;
> +	} else {
> +		return -ENOMEM;
> +	}

Reverse this if statement to make the success path more obvious.

> +
> +
> +	/* Now add the file system entries */
> +
> +	fsinst = fs_to_install;
> +
> +	while (fsinst->fst && !error) {
> +		error = register_filesystem(fsinst->fst);
> +		if (!error)
> +			fsinst->installed = 1;
> +		fsinst++;
> +	}
> +
> +	/* Any errors? uninstall  */
> +	if (error) {
> +		fsinst = fs_to_install;
> +
> +		while (fsinst->fst) {
> +			if (fsinst->installed) {
> +				unregister_filesystem(fsinst->fst);
> +				fsinst->installed = 0;
> +			}
> +			fsinst++;
> +		}
> +	}
> +
> +	return error;
> +}
> +
> +static void __exit exit_yaffs_fs(void)
> +{
> +
> +	struct file_system_to_install *fsinst;
> +
> +	yaffs_trace(YAFFS_TRACE_ALWAYS,
> +		"yaffs built " __DATE__ " " __TIME__ " removing.");
> +
> +	remove_proc_entry("yaffs", NULL);
> +
> +	fsinst = fs_to_install;
> +
> +	while (fsinst->fst) {
> +		if (fsinst->installed) {
> +			unregister_filesystem(fsinst->fst);
> +			fsinst->installed = 0;
> +		}
> +		fsinst++;
> +	}
> +}
> +
> +module_init(init_yaffs_fs)
> +module_exit(exit_yaffs_fs)
> +
> +MODULE_DESCRIPTION("YAFFS2 - a NAND specific flash file system");
> +MODULE_AUTHOR("Charles Manning, Aleph One Ltd., 2002-2011");
> +MODULE_LICENSE("GPL");
> diff --git a/fs/yaffs2/yportenv.h b/fs/yaffs2/yportenv.h
> new file mode 100644
> index 0000000..aa7c22b
> --- /dev/null
> +++ b/fs/yaffs2/yportenv.h
> @@ -0,0 +1,59 @@
> +/*
> + * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
> + *
> + * Copyright (C) 2002-2011 Aleph One Ltd.
> + *   for Toby Churchill Ltd and Brightstar Engineering
> + *
> + * Created by Charles Manning <charles@aleph1.co.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License version 2.1 as
> + * published by the Free Software Foundation.
> + *
> + * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
> + */
> +
> +#ifndef __YPORTENV_LINUX_H__
> +#define __YPORTENV_LINUX_H__
> +
> +#include <linux/version.h>
> +#include <linux/kernel.h>
> +#include <linux/mm.h>
> +#include <linux/sched.h>
> +#include <linux/string.h>
> +#include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +#include <linux/xattr.h>
> +#include <linux/list.h>
> +#include <linux/types.h>
> +#include <linux/fs.h>
> +#include <linux/stat.h>
> +#include <linux/sort.h>
> +#include <linux/bitops.h>
> +
> +/*  These type wrappings are used to support Unicode names in WinCE. */
> +#define YCHAR char
> +#define YUCHAR unsigned char
> +#define _Y(x)     x
> +
> +#define YAFFS_LOSTNFOUND_NAME		"lost+found"
> +#define YAFFS_LOSTNFOUND_PREFIX		"obj"
> +
> +
> +#define YAFFS_ROOT_MODE			0755
> +#define YAFFS_LOSTNFOUND_MODE		0700
> +
> +#define Y_CURRENT_TIME CURRENT_TIME.tv_sec
> +#define Y_TIME_CONVERT(x) (x).tv_sec
> +
> +#define compile_time_assertion(assertion) \
> +	({ int x = __builtin_choose_expr(assertion, 0, (void)0); (void) x; })

This can probably be replaced with BUILD_BUG_ON and friends.

> +
> +
> +#define yaffs_trace(msk, fmt, ...) do { \
> +	if (yaffs_trace_mask & (msk)) \
> +		printk(KERN_DEBUG "yaffs: " fmt "\n", ##__VA_ARGS__); \
> +} while (0)

Using pr_debug here would allow you to completly remove all of the
tracing code if you don't need debugging output. Handy for embedded
devices, which is what yaffs is aimed at. You can #define DEBUG at the
top of this file to include debugging support, or add it as a Kconfig
option.

~Ryan

-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

Re: [PATCH 09/10] Add yaffs2 file system: Linux glue code

[Charles Manning]

On Friday 11 February 2011 11:07:31 Ryan Mallon wrote:
> On 02/09/2011 04:26 PM, Charles Manning wrote:
> > Signed-off-by: Charles Manning <cdhmanning@gmail.com>
>
> Hi Charles,
>
> More comments below. The locking I think needs some work before this is
> okay for mainline. It would be interesting to stress test yaffs on an
> SMP machine. None of the boards which we run yaffs on are though :-(.

yaffs can be run on a PC using nandsim and I have done so with the 
multi-version code. I am setting up another PC for single-version (ie. 
mainlining) testing.

I'll take an in depth look at your comments, but it is important to understand 
the locking model a bit better,

yaffs just uses one big lock. We need to consider locking for many reasons and 
need to ensure that stuff does not get modified behind our back. For example 
setattr on one object can cause garbage collection to change the flash 
location - and thus the tnode tree - of another object.

There is probably scope to change the gross locking model to a r/w lock which 
would mean that read operations could proceed better.

I did a non-open-source project of looking at finer grained locking but found 
that there were not many gains for what I looked at. Ultimately anything that 
goes to flash is serialised by the flash access.

-- Charles

Re: [PATCH 09/10] Add yaffs2 file system: Linux glue code

[Ryan Mallon]

On 02/09/2011 04:26 PM, Charles Manning wrote:
> Signed-off-by: Charles Manning <cdhmanning@gmail.com>
> ---

<snip>

> +/*
> + * yaffs_search_end() disposes of a search context and cleans up.
> + */
> +static void yaffs_search_end(struct yaffs_search_context *sc)
> +{
> +	if (sc) {

This test, and the similar one in yaffs_search_advance, are not needed.
There is no way that sc can be passed as NULL here. Even if that could
happen you probably want to oops rather than silently carrying on.

I think there are similar issues in other functions throughout the yaffs
code where you are testing if various pointers are NULL and returning
silently if they are. All of these cases should be fixed to remove the
extraneous code.

~Ryan

-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934