[PATCH] Btrfs image tool

[Yan Zheng <zheng.yan@oracle.com>]

Hello,

This patch adds btrfs image tool. The image tool is
a debugging tool that creates/restores btrfs metadump
image. Thank you,

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

---
diff -urpN btrfs-progs-orig/btrfs-image.c btrfs-progs/btrfs-image.c
--- btrfs-progs-orig/btrfs-image.c	1970-01-01 07:00:00.000000000 +0700
+++ btrfs-progs/btrfs-image.c	2008-11-19 22:52:31.000000000 +0800
@@ -0,0 +1,853 @@
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#define _XOPEN_SOURCE 500
+#define _GNU_SOURCE 1
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <zlib.h>
+#include "kerncompat.h"
+#include "crc32c.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "utils.h"
+#include "version.h"
+
+
+#define HEADER_MAGIC		0xbd5c25e27295668bULL
+#define MAX_PENDING_SIZE	(256 * 1024)
+#define BLOCK_SIZE		1024
+#define BLOCK_MASK		(BLOCK_SIZE - 1)
+
+#define COMPRESS_NONE		0
+#define COMPRESS_ZLIB		1
+
+struct meta_cluster_item {
+	__le64 bytenr;
+	__le32 size;
+} __attribute__ ((__packed__));
+
+struct meta_cluster_header {
+	__le64 magic;
+	__le64 bytenr;
+	__le32 nritems;
+	u8 compress;
+} __attribute__ ((__packed__));
+
+/* cluster header + index items + buffers */
+struct meta_cluster {
+	struct meta_cluster_header header;
+	struct meta_cluster_item items[];
+} __attribute__ ((__packed__));
+
+#define ITEMS_PER_CLUSTER ((BLOCK_SIZE - sizeof(struct meta_cluster)) / \
+			   sizeof(struct meta_cluster_item))
+
+struct async_work {
+	struct list_head list;
+	struct list_head ordered;
+	u64 start;
+	u64 size;
+	u8 *buffer;
+	size_t bufsize;
+};
+
+struct metadump_struct {
+	struct btrfs_root *root;
+	FILE *out;
+
+	struct meta_cluster *cluster;
+
+	pthread_t *threads;
+	size_t num_threads;
+	pthread_mutex_t mutex;
+	pthread_cond_t cond;
+
+	struct list_head list;
+	struct list_head ordered;
+	size_t num_items;
+	size_t num_ready;
+
+	u64 pending_start;
+	u64 pending_size;
+
+	int compress_level;
+	int done;
+};
+
+struct mdrestore_struct {
+	FILE *in;
+	FILE *out;
+
+	pthread_t *threads;
+	size_t num_threads;
+	pthread_mutex_t mutex;
+	pthread_cond_t cond;
+
+	struct list_head list;
+	size_t num_items;
+
+	int compress_method;
+	int done;
+};
+
+static void csum_block(u8 *buf, size_t len)
+{
+	char result[BTRFS_CRC32_SIZE];
+	u32 crc = ~(u32)0;
+	crc = crc32c(crc, buf + BTRFS_CSUM_SIZE, len - BTRFS_CSUM_SIZE);
+	btrfs_csum_final(crc, result);
+	memcpy(buf, result, BTRFS_CRC32_SIZE);
+}
+
+/*
+ * zero inline extents and csum items
+ */
+static void zero_items(u8 *dst, struct extent_buffer *src)
+{
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_item *item;
+	struct btrfs_key key;
+	u32 nritems = btrfs_header_nritems(src);
+	size_t size;
+	unsigned long ptr;
+	int i, extent_type;
+
+	for (i = 0; i < nritems; i++) {
+		item = btrfs_item_nr(src, i);
+		btrfs_item_key_to_cpu(src, &key, i);
+		if (key.type == BTRFS_CSUM_ITEM_KEY) {
+			size = btrfs_item_size_nr(src, i);
+			memset(dst + btrfs_leaf_data(src) +
+			       btrfs_item_offset_nr(src, i), 0, size);
+			continue;
+		}
+		if (key.type != BTRFS_EXTENT_DATA_KEY)
+			continue;
+
+		fi = btrfs_item_ptr(src, i, struct btrfs_file_extent_item);
+		extent_type = btrfs_file_extent_type(src, fi);
+		if (extent_type != BTRFS_FILE_EXTENT_INLINE)
+			continue;
+
+		ptr = btrfs_file_extent_inline_start(fi);
+		size = btrfs_file_extent_inline_item_len(src, item);
+		memset(dst + ptr, 0, size);
+	}
+}
+
+/*
+ * copy buffer and zero useless data in the buffer
+ */
+static void copy_buffer(u8 *dst, struct extent_buffer *src)
+{
+	int level;
+	size_t size;
+	u32 nritems;
+
+	memcpy(dst, src->data, src->len);
+	if (src->start == BTRFS_SUPER_INFO_OFFSET)
+		return;
+
+	level = btrfs_header_level(src);
+	nritems = btrfs_header_nritems(src);
+
+	if (nritems == 0) {
+		size = sizeof(struct btrfs_header);
+		memset(dst + size, 0, src->len - size);
+	} else if (level == 0) {
+		size = btrfs_leaf_data(src) +
+			btrfs_item_offset_nr(src, nritems - 1) -
+			btrfs_item_nr_offset(nritems);
+		memset(dst + btrfs_item_nr_offset(nritems), 0, size);
+		zero_items(dst, src);
+	} else {
+		size = offsetof(struct btrfs_node, ptrs) +
+			sizeof(struct btrfs_key_ptr) * nritems;
+		memset(dst + size, 0, src->len - size);
+	}
+	csum_block(dst, src->len);
+}
+
+static void *dump_worker(void *data)
+{
+	struct metadump_struct *md = (struct metadump_struct *)data;
+	struct async_work *async;
+	int ret;
+
+	while (1) {
+		pthread_mutex_lock(&md->mutex);
+		while (list_empty(&md->list)) {
+			if (md->done) {
+				pthread_mutex_unlock(&md->mutex);
+				goto out;
+			}
+			pthread_cond_wait(&md->cond, &md->mutex);
+		}
+		async = list_entry(md->list.next, struct async_work, list);
+		list_del_init(&async->list);
+		pthread_mutex_unlock(&md->mutex);
+
+		if (md->compress_level > 0) {
+			u8 *orig = async->buffer;
+
+			async->bufsize = compressBound(async->size);
+			async->buffer = malloc(async->bufsize);
+
+			ret = compress2(async->buffer, &async->bufsize, orig,
+					async->size, md->compress_level);
+			BUG_ON(ret != Z_OK);
+
+			free(orig);
+		}
+
+		pthread_mutex_lock(&md->mutex);
+		md->num_ready++;
+		pthread_mutex_unlock(&md->mutex);
+	}
+out:
+	pthread_exit(NULL);
+}
+
+static void meta_cluster_init(struct metadump_struct *md, u64 start)
+{
+	struct meta_cluster_header *header;
+
+	md->num_items = 0;
+	md->num_ready = 0;
+	header = &md->cluster->header;
+	header->magic = cpu_to_le64(HEADER_MAGIC);
+	header->bytenr = cpu_to_le64(start);
+	header->nritems = cpu_to_le32(0);
+	header->compress = md->compress_level > 0 ?
+			   COMPRESS_ZLIB : COMPRESS_NONE;
+}
+
+static int metadump_init(struct metadump_struct *md, struct btrfs_root *root,
+			 FILE *out, int num_threads, int compress_level)
+{
+	int i, ret;
+
+	memset(md, 0, sizeof(*md));
+	pthread_cond_init(&md->cond, NULL);
+	pthread_mutex_init(&md->mutex, NULL);
+	INIT_LIST_HEAD(&md->list);
+	INIT_LIST_HEAD(&md->ordered);
+	md->root = root;
+	md->out = out;
+	md->pending_start = (u64)-1;
+	md->compress_level = compress_level;
+	md->cluster = calloc(1, BLOCK_SIZE);
+	if (!md->cluster)
+		return -ENOMEM;
+
+	meta_cluster_init(md, 0);
+	if (!num_threads)
+		return 0;
+
+	md->num_threads = num_threads;
+	md->threads = calloc(num_threads, sizeof(pthread_t));
+	if (!md->threads)
+		return -ENOMEM;
+	for (i = 0; i < num_threads; i++) {
+		ret = pthread_create(md->threads + i, NULL, dump_worker, md);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+static void metadump_destroy(struct metadump_struct *md)
+{
+	int i;
+	pthread_mutex_lock(&md->mutex);
+	md->done = 1;
+	pthread_cond_broadcast(&md->cond);
+	pthread_mutex_unlock(&md->mutex);
+
+	for (i = 0; i < md->num_threads; i++)
+		pthread_join(md->threads[i], NULL);
+
+	pthread_cond_destroy(&md->cond);
+	pthread_mutex_destroy(&md->mutex);
+	free(md->threads);
+	free(md->cluster);
+}
+
+static int write_zero(FILE *out, size_t size)
+{
+	static char zero[BLOCK_SIZE];
+	return fwrite(zero, size, 1, out);
+}
+
+static int write_buffers(struct metadump_struct *md, u64 *next)
+{
+	struct meta_cluster_header *header = &md->cluster->header;
+	struct meta_cluster_item *item;
+	struct async_work *async;
+	u64 bytenr = 0;
+	u32 nritems = 0;
+	int ret;
+
+	if (list_empty(&md->ordered))
+		goto out;
+
+	/* wait until all buffers are compressed */
+	while (md->num_items > md->num_ready) {
+		struct timespec ts = {
+			.tv_sec = 0,
+			.tv_nsec = 10000000,
+		};
+		pthread_mutex_unlock(&md->mutex);
+		nanosleep(&ts, NULL);
+		pthread_mutex_lock(&md->mutex);
+	}
+
+	/* setup and write index block */
+	list_for_each_entry(async, &md->ordered, ordered) {
+		item = md->cluster->items + nritems;
+		item->bytenr = cpu_to_le64(async->start);
+		item->size = cpu_to_le32(async->bufsize);
+		nritems++;
+	}
+	header->nritems = cpu_to_le32(nritems);
+
+	ret = fwrite(md->cluster, BLOCK_SIZE, 1, md->out);
+	BUG_ON(ret != 1);
+
+	/* write buffers */
+	bytenr += le64_to_cpu(header->bytenr) + BLOCK_SIZE;
+	while (!list_empty(&md->ordered)) {
+		async = list_entry(md->ordered.next, struct async_work,
+				   ordered);
+		list_del_init(&async->ordered);
+
+		bytenr += async->bufsize;
+		ret = fwrite(async->buffer, async->bufsize, 1, md->out);
+		BUG_ON(ret != 1);
+
+		free(async->buffer);
+		free(async);
+	}
+
+	/* zero unused space in the last block */
+	if (bytenr & BLOCK_MASK) {
+		size_t size = BLOCK_SIZE - (bytenr & BLOCK_MASK);
+
+		bytenr += size;
+		ret = write_zero(md->out, size);
+		BUG_ON(ret != 1);
+	}
+out:
+	*next = bytenr;
+	return 0;
+}
+
+static int flush_pending(struct metadump_struct *md, int done)
+{
+	struct async_work *async = NULL;
+	struct extent_buffer *eb;
+	u64 blocksize = md->root->nodesize;
+	u64 start;
+	u64 size;
+	size_t offset;
+	int ret;
+
+	if (md->pending_size) {
+		async = calloc(1, sizeof(*async));
+		if (!async)
+			return -ENOMEM;
+
+		async->start = md->pending_start;
+		async->size = md->pending_size;
+		async->bufsize = async->size;
+		async->buffer = malloc(async->bufsize);
+
+		offset = 0;
+		start = async->start;
+		size = async->size;
+		while (size > 0) {
+			eb = read_tree_block(md->root, start, blocksize, 0);
+			BUG_ON(!eb);
+			copy_buffer(async->buffer + offset, eb);
+			free_extent_buffer(eb);
+			start += blocksize;
+			offset += blocksize;
+			size -= blocksize;
+		}
+
+		md->pending_start = (u64)-1;
+		md->pending_size = 0;
+	} else if (!done) {
+		return 0;
+	}
+
+	pthread_mutex_lock(&md->mutex);
+	if (async) {
+		list_add_tail(&async->ordered, &md->ordered);
+		md->num_items++;
+		if (md->compress_level > 0) {
+			list_add_tail(&async->list, &md->list);
+			pthread_cond_signal(&md->cond);
+		} else {
+			md->num_ready++;
+		}
+	}
+	if (md->num_items >= ITEMS_PER_CLUSTER || done) {
+		ret = write_buffers(md, &start);
+		BUG_ON(ret);
+		meta_cluster_init(md, start);
+	}
+	pthread_mutex_unlock(&md->mutex);
+	return 0;
+}
+
+static int add_metadata(u64 start, u64 size, struct metadump_struct *md)
+{
+	int ret;
+	if (md->pending_size + size > MAX_PENDING_SIZE ||
+	    md->pending_start + md->pending_size != start) {
+		ret = flush_pending(md, 0);
+		if (ret)
+			return ret;
+		md->pending_start = start;
+	}
+	readahead_tree_block(md->root, start, size, 0);
+	md->pending_size += size;
+	return 0;
+}
+
+static int create_metadump(const char *input, FILE *out, int num_threads,
+			   int compress_level)
+{
+	struct btrfs_root *root;
+	struct btrfs_root *extent_root;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_extent_ref *ref_item;
+	struct btrfs_key key;
+	struct metadump_struct metadump;
+	u64 bytenr;
+	u64 num_bytes;
+	u64 ref_objectid;
+	int ret;
+
+	root = open_ctree(input, 0, 0);
+	BUG_ON(root->nodesize != root->leafsize);
+
+	ret = metadump_init(&metadump, root, out, num_threads,
+			    compress_level);
+	BUG_ON(ret);
+
+	ret = add_metadata(BTRFS_SUPER_INFO_OFFSET, 4096, &metadump);
+	BUG_ON(ret);
+
+	extent_root = root->fs_info->extent_root;
+	path = btrfs_alloc_path();
+
+	bytenr = BTRFS_SUPER_INFO_OFFSET + 4096;
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_ITEM_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
+	BUG_ON(ret < 0);
+
+	while (1) {
+		leaf = path->nodes[0];
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(extent_root, path);
+			BUG_ON(ret < 0);
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		if (key.objectid < bytenr ||
+		    key.type != BTRFS_EXTENT_ITEM_KEY) {
+			path->slots[0]++;
+			continue;
+		}
+
+		bytenr = key.objectid;
+		num_bytes = key.offset;
+		while (1) {
+			path->slots[0]++;
+			if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+				ret = btrfs_next_leaf(extent_root, path);
+				BUG_ON(ret < 0);
+				if (ret > 0)
+					break;
+				leaf = path->nodes[0];
+			}
+			btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+			if (key.objectid != bytenr)
+				break;
+			if (key.type != BTRFS_EXTENT_REF_KEY)
+				continue;
+			ref_item = btrfs_item_ptr(leaf, path->slots[0],
+						  struct btrfs_extent_ref);
+			ref_objectid = btrfs_ref_objectid(leaf, ref_item);
+			if (ref_objectid < BTRFS_FIRST_FREE_OBJECTID) {
+				ret = add_metadata(bytenr, num_bytes,
+						   &metadump);
+				BUG_ON(ret);
+				break;
+			}
+		}
+		bytenr += num_bytes;
+	}
+
+	ret = flush_pending(&metadump, 1);
+	BUG_ON(ret);
+
+	metadump_destroy(&metadump);
+
+	btrfs_free_path(path);
+	ret = close_ctree(root);
+	return 0;
+}
+
+static void update_super(u8 *buffer)
+{
+	struct btrfs_super_block *super = (struct btrfs_super_block *)buffer;
+	struct btrfs_chunk *chunk;
+	struct btrfs_disk_key *key;
+	u32 sectorsize = btrfs_super_sectorsize(super);
+	u64 flags = btrfs_super_flags(super);
+
+	flags |= BTRFS_SUPER_FLAG_METADUMP;
+	btrfs_set_super_flags(super, flags);
+
+	key = (struct btrfs_disk_key *)(super->sys_chunk_array);
+	chunk = (struct btrfs_chunk *)(super->sys_chunk_array +
+				       sizeof(struct btrfs_disk_key));
+
+	btrfs_set_disk_key_objectid(key, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
+	btrfs_set_disk_key_type(key, BTRFS_CHUNK_ITEM_KEY);
+	btrfs_set_disk_key_offset(key, 0);
+
+	btrfs_set_stack_chunk_length(chunk, (u64)-1);
+	btrfs_set_stack_chunk_owner(chunk, BTRFS_EXTENT_TREE_OBJECTID);
+	btrfs_set_stack_chunk_stripe_len(chunk, 64 * 1024);
+	btrfs_set_stack_chunk_type(chunk, BTRFS_BLOCK_GROUP_SYSTEM);
+	btrfs_set_stack_chunk_io_align(chunk, sectorsize);
+	btrfs_set_stack_chunk_io_width(chunk, sectorsize);
+	btrfs_set_stack_chunk_sector_size(chunk, sectorsize);
+	btrfs_set_stack_chunk_num_stripes(chunk, 1);
+	btrfs_set_stack_chunk_sub_stripes(chunk, 0);
+	chunk->stripe.devid = super->dev_item.devid;
+	chunk->stripe.offset = cpu_to_le64(0);
+	memcpy(chunk->stripe.dev_uuid, super->dev_item.uuid, BTRFS_UUID_SIZE);
+	btrfs_set_super_sys_array_size(super, sizeof(*key) + sizeof(*chunk));
+	csum_block(buffer, 4096);
+}
+
+static void *restore_worker(void *data)
+{
+	struct mdrestore_struct *mdres = (struct mdrestore_struct *)data;
+	struct async_work *async;
+	size_t size;
+	u8 *buffer;
+	u8 *outbuf;
+	int outfd;
+	int ret;
+
+	outfd = fileno(mdres->out);
+	buffer = malloc(MAX_PENDING_SIZE * 2);
+	BUG_ON(!buffer);
+
+	while (1) {
+		pthread_mutex_lock(&mdres->mutex);
+		while (list_empty(&mdres->list)) {
+			if (mdres->done) {
+				pthread_mutex_unlock(&mdres->mutex);
+				goto out;
+			}
+			pthread_cond_wait(&mdres->cond, &mdres->mutex);
+		}
+		async = list_entry(mdres->list.next, struct async_work, list);
+		list_del_init(&async->list);
+		pthread_mutex_unlock(&mdres->mutex);
+
+		if (mdres->compress_method == COMPRESS_ZLIB) {
+			size = MAX_PENDING_SIZE * 2;
+			ret = uncompress(buffer, &size, async->buffer,
+					 async->bufsize);
+			BUG_ON(ret != Z_OK);
+			outbuf = buffer;
+		} else {
+			outbuf = async->buffer;
+			size = async->bufsize;
+		}
+
+		if (async->start == BTRFS_SUPER_INFO_OFFSET)
+			update_super(outbuf);
+
+		ret = pwrite64(outfd, outbuf, size, async->start);
+		BUG_ON(ret != size);
+
+		pthread_mutex_lock(&mdres->mutex);
+		mdres->num_items--;
+		pthread_mutex_unlock(&mdres->mutex);
+
+		free(async->buffer);
+		free(async);
+	}
+out:
+	free(buffer);
+	pthread_exit(NULL);
+}
+
+static int mdresotre_init(struct mdrestore_struct *mdres,
+			  FILE *in, FILE *out, int num_threads)
+{
+	int i, ret = 0;
+
+	memset(mdres, 0, sizeof(*mdres));
+	pthread_cond_init(&mdres->cond, NULL);
+	pthread_mutex_init(&mdres->mutex, NULL);
+	INIT_LIST_HEAD(&mdres->list);
+	mdres->in = in;
+	mdres->out = out;
+
+	if (!num_threads)
+		return 0;
+
+	mdres->num_threads = num_threads;
+	mdres->threads = calloc(num_threads, sizeof(pthread_t));
+	if (!mdres->threads)
+		return -ENOMEM;
+	for (i = 0; i < num_threads; i++) {
+		ret = pthread_create(mdres->threads + i, NULL, restore_worker,
+				     mdres);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+static void mdresotre_destroy(struct mdrestore_struct *mdres)
+{
+	int i;
+	pthread_mutex_lock(&mdres->mutex);
+	mdres->done = 1;
+	pthread_cond_broadcast(&mdres->cond);
+	pthread_mutex_unlock(&mdres->mutex);
+
+	for (i = 0; i < mdres->num_threads; i++)
+		pthread_join(mdres->threads[i], NULL);
+
+	pthread_cond_destroy(&mdres->cond);
+	pthread_mutex_destroy(&mdres->mutex);
+	free(mdres->threads);
+}
+
+static int add_cluster(struct meta_cluster *cluster,
+		       struct mdrestore_struct *mdres, u64 *next)
+{
+	struct meta_cluster_item *item;
+	struct meta_cluster_header *header = &cluster->header;
+	struct async_work *async;
+	u64 bytenr;
+	u32 i, nritems;
+	int ret;
+
+	BUG_ON(mdres->num_items);
+	mdres->compress_method = header->compress;
+
+	bytenr = le64_to_cpu(header->bytenr) + BLOCK_SIZE;
+	nritems = le32_to_cpu(header->nritems);
+	for (i = 0; i < nritems; i++) {
+		item = &cluster->items[i];
+		async = calloc(1, sizeof(*async));
+		async->start = le64_to_cpu(item->bytenr);
+		async->bufsize = le32_to_cpu(item->size);
+		async->buffer = malloc(async->bufsize);
+		ret = fread(async->buffer, async->bufsize, 1, mdres->in);
+		BUG_ON(ret != 1);
+		bytenr += async->bufsize;
+
+		pthread_mutex_lock(&mdres->mutex);
+		list_add_tail(&async->list, &mdres->list);
+		mdres->num_items++;
+		pthread_cond_signal(&mdres->cond);
+		pthread_mutex_unlock(&mdres->mutex);
+	}
+	if (bytenr & BLOCK_MASK) {
+		char buffer[BLOCK_MASK];
+		size_t size = BLOCK_SIZE - (bytenr & BLOCK_MASK);
+
+		bytenr += size;
+		ret = fread(buffer, size, 1, mdres->in);
+		BUG_ON(ret != 1);
+	}
+	*next = bytenr;
+	return 0;
+}
+
+static int wait_for_worker(struct mdrestore_struct *mdres)
+{
+	pthread_mutex_lock(&mdres->mutex);
+	while (mdres->num_items > 0) {
+		struct timespec ts = {
+			.tv_sec = 0,
+			.tv_nsec = 10000000,
+		};
+		pthread_mutex_unlock(&mdres->mutex);
+		nanosleep(&ts, NULL);
+		pthread_mutex_lock(&mdres->mutex);
+	}
+	pthread_mutex_unlock(&mdres->mutex);
+	return 0;
+}
+
+static int restore_metadump(const char *input, FILE *out, int num_threads)
+{
+	struct meta_cluster *cluster;
+	struct meta_cluster_header *header;
+	struct mdrestore_struct mdrestore;
+	u64 bytenr = 0;
+	FILE *in;
+	int ret;
+
+	if (!strcmp(input, "-")) {
+		in = stdin;
+	} else {
+		in = fopen(input, "r");
+		if (!in) {
+			perror("unable to open metadump image");
+			exit(1);
+		}
+	}
+
+	cluster = malloc(BLOCK_SIZE);
+	BUG_ON(!cluster);
+
+	ret = mdresotre_init(&mdrestore, in, out, num_threads);
+	BUG_ON(ret);
+
+	while (1) {
+		ret = fread(cluster, BLOCK_SIZE, 1, in);
+		if (!ret)
+			break;
+
+		header = &cluster->header;
+		if (le64_to_cpu(header->magic) != HEADER_MAGIC ||
+		    le64_to_cpu(header->bytenr) != bytenr) {
+			fprintf(stderr, "bad header in metadump image\n");
+			exit(1);
+		}
+		ret = add_cluster(cluster, &mdrestore, &bytenr);
+		BUG_ON(ret);
+
+		wait_for_worker(&mdrestore);
+	}
+
+	mdresotre_destroy(&mdrestore);
+	free(cluster);
+	if (in != stdin)
+		fclose(in);
+	return ret;
+}
+
+static void print_usage(void)
+{
+	fprintf(stderr, "usage: btrfs-image [options] source target\n");
+	fprintf(stderr, "\t-r      \trestore metadump image\n");
+	fprintf(stderr, "\t-c value\tcompression level (0 ~ 9)\n");
+	fprintf(stderr, "\t-t value\tnumber of threads (1 ~ 32)\n");
+	exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+	char *source;
+	char *target;
+	int num_threads = 0;
+	int compress_level = 0;
+	int create = 1;
+	int ret;
+	FILE *out;
+
+	while (1) {
+		int c = getopt(argc, argv, "rc:t:");
+		if (c < 0)
+			break;
+		switch (c) {
+		case 'r':
+			create = 0;
+			break;
+		case 't':
+			num_threads = atoi(optarg);
+			if (num_threads <= 0 || num_threads > 32)
+				print_usage();
+			break;
+		case 'c':
+			compress_level = atoi(optarg);
+			if (compress_level < 0 || compress_level > 9)
+				print_usage();
+			break;
+		default:
+			print_usage();
+		}
+	}
+
+	argc = argc - optind;
+	if (argc != 2)
+		print_usage();
+	source = argv[optind];
+	target = argv[optind + 1];
+
+	if (create && !strcmp(target, "-")) {
+		out = stdout;
+	} else {
+		out = fopen(target, "w+");
+		if (!out) {
+			perror("unable to create target file");
+			exit(1);
+		}
+	}
+
+	if (num_threads == 0 && compress_level > 0) {
+		num_threads = sysconf(_SC_NPROCESSORS_ONLN);
+		if (num_threads <= 0)
+			num_threads = 1;
+	}
+
+	if (create)
+		ret = create_metadump(source, out, num_threads,
+				      compress_level);
+	else
+		ret = restore_metadump(source, out, 1);
+
+	if (out == stdout)
+		fflush(out);
+	else
+		fclose(out);
+
+	exit(0);
+}
diff -urpN btrfs-progs-orig/ctree.h btrfs-progs/ctree.h
--- btrfs-progs-orig/ctree.h	2008-11-19 07:30:00.000000000 +0800
+++ btrfs-progs/ctree.h	2008-11-19 14:03:24.000000000 +0800
@@ -252,7 +252,8 @@ struct btrfs_header {
 					sizeof(struct btrfs_item) - \
 					sizeof(struct btrfs_file_extent_item))
 
-#define BTRFS_SUPER_FLAG_SEEDING (1ULL << 32)
+#define BTRFS_SUPER_FLAG_SEEDING	(1ULL << 32)
+#define BTRFS_SUPER_FLAG_METADUMP	(1ULL << 33)
 
 /*
  * this is a very generous portion of the super block, giving us
@@ -1362,14 +1363,6 @@ static inline u32 btrfs_file_extent_calc
 	return offsetof(struct btrfs_file_extent_item, disk_bytenr) + datasize;
 }
 
-static inline u32 btrfs_file_extent_inline_len(struct extent_buffer *eb,
-					       struct btrfs_item *e)
-{
-	unsigned long offset;
-	offset = offsetof(struct btrfs_file_extent_item, disk_bytenr);
-	return btrfs_item_size(eb, e) - offset;
-}
-
 BTRFS_SETGET_FUNCS(file_extent_disk_bytenr, struct btrfs_file_extent_item,
 		   disk_bytenr, 64);
 BTRFS_SETGET_FUNCS(file_extent_generation, struct btrfs_file_extent_item,
@@ -1389,6 +1382,28 @@ BTRFS_SETGET_FUNCS(file_extent_encryptio
 BTRFS_SETGET_FUNCS(file_extent_other_encoding, struct btrfs_file_extent_item,
 		   other_encoding, 16);
 
+/* this returns the number of file bytes represented by the inline item.
+ * If an item is compressed, this is the uncompressed size
+ */
+static inline u32 btrfs_file_extent_inline_len(struct extent_buffer *eb,
+					struct btrfs_file_extent_item *e)
+{
+       return btrfs_file_extent_ram_bytes(eb, e);
+}
+
+/*
+ * this returns the number of bytes used by the item on disk, minus the
+ * size of any extent headers.  If a file is compressed on disk, this is
+ * the compressed size
+ */
+static inline u32 btrfs_file_extent_inline_item_len(struct extent_buffer *eb,
+						    struct btrfs_item *e)
+{
+       unsigned long offset;
+       offset = offsetof(struct btrfs_file_extent_item, disk_bytenr);
+       return btrfs_item_size(eb, e) - offset;
+}
+
 static inline u32 btrfs_level_size(struct btrfs_root *root, int level) {
 	if (level == 0)
 		return root->leafsize;
diff -urpN btrfs-progs-orig/disk-io.c btrfs-progs/disk-io.c
--- btrfs-progs-orig/disk-io.c	2008-11-19 07:30:00.000000000 +0800
+++ btrfs-progs/disk-io.c	2008-11-19 13:42:47.000000000 +0800
@@ -646,8 +646,10 @@ struct btrfs_root *open_ctree_fd(int fp,
 	         (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
 		 BTRFS_UUID_SIZE);
 
-	ret = btrfs_read_chunk_tree(chunk_root);
-	BUG_ON(ret);
+	if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
+		ret = btrfs_read_chunk_tree(chunk_root);
+		BUG_ON(ret);
+	}
 
 	blocksize = btrfs_level_size(tree_root,
 				     btrfs_super_root_level(disk_super));
diff -urpN btrfs-progs-orig/file-item.c btrfs-progs/file-item.c
--- btrfs-progs-orig/file-item.c	2008-10-21 09:46:14.000000000 +0800
+++ btrfs-progs/file-item.c	2008-11-19 10:01:55.000000000 +0800
@@ -140,8 +140,7 @@ int btrfs_insert_inline_extent(struct bt
 			       (unsigned long long)objectid);
 			goto fail;
 		}
-		found_size = btrfs_file_extent_inline_len(leaf,
-					  btrfs_item_nr(leaf, path->slots[0]));
+		found_size = btrfs_file_extent_inline_len(leaf, ei);
 		found_end = key.offset + found_size;
 
 		if (found_end < offset + size) {
diff -urpN btrfs-progs-orig/Makefile btrfs-progs/Makefile
--- btrfs-progs-orig/Makefile	2008-11-19 07:30:00.000000000 +0800
+++ btrfs-progs/Makefile	2008-11-19 22:29:02.000000000 +0800
@@ -15,7 +15,8 @@ prefix ?= /usr/local
 bindir = $(prefix)/bin
 LIBS=-luuid
 
-progs = btrfsctl btrfsck mkfs.btrfs debug-tree btrfs-show btrfs-vol btrfstune
+progs = btrfsctl btrfsck mkfs.btrfs debug-tree btrfs-show btrfs-vol \
+	btrfstune btrfs-image
 
 # make C=1 to enable sparse
 ifdef C
@@ -55,6 +56,9 @@ debug-tree: $(objects) debug-tree.o
 btrfstune: $(objects) btrfstune.o
 	gcc $(CFLAGS) -o btrfstune $(objects) btrfstune.o $(LDFLAGS) $(LIBS)
 
+btrfs-image: $(objects) btrfs-image.o
+	gcc $(CFLAGS) -o btrfs-image $(objects) btrfs-image.o -lpthread -lz $(LDFLAGS) $(LIBS)
+
 dir-test: $(objects) dir-test.o
 	gcc $(CFLAGS) -o dir-test $(objects) dir-test.o $(LDFLAGS) $(LIBS)
 
diff -urpN btrfs-progs-orig/print-tree.c btrfs-progs/print-tree.c
--- btrfs-progs-orig/print-tree.c	2008-11-19 07:30:00.000000000 +0800
+++ btrfs-progs/print-tree.c	2008-11-19 14:05:59.000000000 +0800
@@ -132,9 +132,9 @@ static void print_file_extent_item(struc
 
 	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 		printf("\t\tinline extent data size %u "
-		       "ram %llu compress %d\n",
-	          btrfs_file_extent_inline_len(eb, item),
-		  (unsigned long long) btrfs_file_extent_ram_bytes(eb, fi),
+		       "ram %u compress %d\n",
+		  btrfs_file_extent_inline_item_len(eb, item),
+		  btrfs_file_extent_inline_len(eb, fi),
 		  btrfs_file_extent_compression(eb, fi));
 		return;
 	}
diff -urpN btrfs-progs-orig/volumes.c btrfs-progs/volumes.c
--- btrfs-progs-orig/volumes.c	2008-11-19 07:30:00.000000000 +0800
+++ btrfs-progs/volumes.c	2008-11-19 13:41:37.000000000 +0800
@@ -222,7 +222,10 @@ int btrfs_scan_one_device(int fd, const 
 		goto error_brelse;
 	}
 	devid = le64_to_cpu(disk_super->dev_item.devid);
-	*total_devs = btrfs_super_num_devices(disk_super);
+	if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)
+		*total_devs = 1;
+	else
+		*total_devs = btrfs_super_num_devices(disk_super);
 	uuid_unparse(disk_super->fsid, uuidbuf);
 
 	ret = device_list_add(path, disk_super, devid, fs_devices_ret);