[PATCH v2] Ceph: Punch hole support

[Li Wang <liwang@ubuntukylin.com>]

This patch implements punch hole (fallocate) support for Ceph.

Signed-off-by: Li Wang <liwang@ubuntukylin.com>
Signed-off-by: Yunchuan Wen <wenyunchuan@ubuntukylin.com>
---
  fs/ceph/file.c        |  313 
+++++++++++++++++++++++++++++++++++++++++++++++++
  net/ceph/osd_client.c |    8 +-
  2 files changed, 319 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 656e169..578e5fd 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -8,6 +8,7 @@
  #include <linux/namei.h>
  #include <linux/writeback.h>
  #include <linux/aio.h>
+#include <linux/falloc.h>

  #include "super.h"
  #include "mds_client.h"
@@ -882,6 +883,317 @@ out:
  	return offset;
  }

+static inline void ceph_zero_partial_page(struct inode *inode, pgoff_t 
index, unsigned start, unsigned size)
+{
+	struct page *page;
+
+	page = find_lock_page(inode->i_mapping, index);
+	if (page) {
+		zero_user(page, start, size);
+		unlock_page(page);
+		page_cache_release(page);
+	}	
+}
+
+static void ceph_truncate_and_zero_page_cache(struct inode *inode, 
loff_t offset, loff_t length)
+{
+	loff_t first_page;
+	loff_t last_page;
+	loff_t zero_len;
+
+	first_page =((offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) << 
PAGE_CACHE_SHIFT;
+	last_page = ((offset + length) >> PAGE_CACHE_SHIFT) << PAGE_CACHE_SHIFT;
+	if (last_page > first_page) {
+		truncate_pagecache_range(inode, first_page, last_page - 1);
+	}
+	if (first_page > last_page) {
+		ceph_zero_partial_page(inode, offset >> PAGE_CACHE_SHIFT, offset & 
(PAGE_CACHE_SIZE - 1), length);
+		return;
+	}
+	/*
+	 * zero out the partial page that contains
+	 * the start of the hole
+	 */	
+	zero_len  = first_page - offset;
+	if (zero_len > 0) {
+		ceph_zero_partial_page(inode, offset >> PAGE_CACHE_SHIFT, offset & 
(PAGE_CACHE_SIZE -1), zero_len);
+	}
+	/*
+	 * zero out the partial page that contains
+	 * the end of the hole
+	 */
+	zero_len = offset + length - last_page;
+	if (zero_len > 0) {
+		ceph_zero_partial_page(inode, (offset + length) >> PAGE_CACHE_SHIFT, 
0, zero_len);
+	}
+	/*
+	 * If i_size is contained in the last page, we need to
+	 * zero the partial page after i_size
+	 */
+	if (inode->i_size >> PAGE_CACHE_SHIFT == (offset + length) >> 
PAGE_CACHE_SHIFT && inode->i_size % PAGE_CACHE_SIZE != 0) {
+		zero_len = PAGE_CACHE_SIZE -
+			(inode->i_size & (PAGE_CACHE_SIZE - 1));
+		if (zero_len > 0) {
+			ceph_zero_partial_page(inode, inode->i_size >> PAGE_CACHE_SHIFT, 
inode->i_size & (PAGE_CACHE_SIZE -1), zero_len);
+		}
+	}
+}
+
+static inline __u32 ceph_calculate_shift(__s64 size)
+{
+	int shift;
+	
+	if (size <= 0)
+		return -1;
+	if (size == 1)
+		return 0;
+	for (shift = 0; ;shift++) {
+		if (2 << shift == size)
+			break;
+	}
+	shift++;
+	
+	return shift;
+}
+
+static int ceph_delete_object(struct inode *inode, u64 offset, u64 *length)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+    struct ceph_fs_client *fsc = ceph_inode_to_client(inode);	
+	struct ceph_osd_request *req;
+	int ret = 0;
+	
+	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+                                    ceph_vino(inode), offset, length, 1,
+                                    CEPH_OSD_OP_DELETE, 
CEPH_OSD_FLAG_ONDISK,
+                                    NULL,
+                                    ci->i_truncate_seq, 
ci->i_truncate_size,
+                                    false);
+	if (IS_ERR(req)) {
+    	ret = PTR_ERR(req);
+		goto out;
+	}
+
+    ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+    if (!ret) {
+        ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
+    }
+	ceph_osdc_put_request(req);
+
+	out:
+	return ret;
+}
+
+static int ceph_zero_partial_object(struct inode *inode, loff_t offset, 
loff_t *length)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_osd_request *req;
+	int ret = 0;
+	
+	if (length <= 0)
+		goto out;
+
+	
+	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+                                    ceph_vino(inode), offset, length, 1,
+                                    CEPH_OSD_OP_ZERO, 
CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+                                    NULL,
+                                    ci->i_truncate_seq, 
ci->i_truncate_size,
+                                    false);
+	if (IS_ERR(req)) {
+    	ret = PTR_ERR(req);
+		goto out;
+	}
+
+    ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+    if (!ret) {
+        ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
+    }
+	ceph_osdc_put_request(req); 	
+
+	out:
+	return ret;
+}
+
+static int ceph_zero_partial_object_set(struct inode *inode, loff_t 
start, loff_t end)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	__s32 stripe_unit_size = ceph_file_layout_su(ci->i_layout);	
+	__u32 stripe_unit_shift = ceph_calculate_shift(stripe_unit_size);
+	loff_t first_stripe_unit = ((start + stripe_unit_size -1 ) >> 
stripe_unit_shift) << stripe_unit_shift;
+	loff_t last_stripe_unit = ((end + 1) >> stripe_unit_shift) << 
stripe_unit_shift;
+	u64 i;
+	loff_t length;
+	int ret = 0;
+
+	if (last_stripe_unit > first_stripe_unit) {
+		for (i = first_stripe_unit; i < last_stripe_unit; i += 
stripe_unit_size) {
+			length = (u64) stripe_unit_size;
+			ret = ceph_zero_partial_object(inode, i, &length);
+			if (ret)
+				goto out;
+		}
+	}
+	if (first_stripe_unit > last_stripe_unit) {
+			length = end - start + 1;			
+			ret = ceph_zero_partial_object(inode, start, &length);
+			goto out;
+	}
+	length = first_stripe_unit - start;
+	if (length > 0) {			
+		ret = ceph_zero_partial_object(inode, start, &length);
+		if (ret)
+			goto out;
+	}
+	length =  end - last_stripe_unit + 1;
+	if (length > 0) {			
+		ret = ceph_zero_partial_object(inode, last_stripe_unit, &length);
+	}
+
+	out:
+	return ret;
+}
+
+static int ceph_delete_and_zero_objects(struct file *file, loff_t 
offset, loff_t length)
+{
+	struct ceph_file_info *fi = file->private_data;	
+	struct inode *inode = file->f_dentry->d_inode;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	__s32 stripe_unit_size = ceph_file_layout_su(ci->i_layout);
+	__s32 stripe_count = ceph_file_layout_stripe_count(ci->i_layout);
+	unsigned stripe_width = ceph_file_layout_stripe_width(&ci->i_layout);
+	__s32 object_size = ceph_file_layout_object_size(ci->i_layout);
+	__s32 object_set_size = object_size * stripe_count;
+	__u32 object_set_shift = ceph_calculate_shift(object_set_size);
+	__u32 stripe_unit_count_per_object = object_size / stripe_unit_size;
+	loff_t first_object_set = ((offset + object_set_size - 1) >> 
object_set_shift) << object_set_shift;
+	loff_t last_object_set = ((offset + length) >> object_set_shift) << 
object_set_shift;
+	loff_t i, j;	
+	int want, got = 0;
+	int dirty;
+	u64 len;
+	int ret = 0;
+
+	if (fi->fmode & CEPH_FILE_MODE_LAZY)
+		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
+	else
+		want = CEPH_CAP_FILE_BUFFER;
+		
+	ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, &got, offset + length);
+	if (ret < 0)
+		return ret;
+	if (!(got & (CEPH_CAP_FILE_BUFFER|CEPH_CAP_FILE_LAZYIO))) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	/* [offset, offset+length] does not across object set bundary.
+	  * Yes, there are possibilities to delete some objects within
+	  * a object set, however, we want to keep it simple, not to incur
+	  * comprehensive calculation, so for a partial hole within a object
+	  * set, we zero only
+	  */
+	if (first_object_set > last_object_set) {
+		ret = ceph_zero_partial_object_set(inode, offset, offset + length - 1);
+		goto out;
+	}
+	/* [offset, offset+length] contains at least one complete object set */
+	if (last_object_set > first_object_set) {		
+		len = (u64)stripe_unit_size;
+		/*
+		  * For the very first object, zero it instead of deleting it,
+		  * since there are attached metada on it
+		  */
+		if (first_object_set == 0) {
+			for (i = 0; i < stripe_unit_count_per_object; i++) {
+				ret = ceph_zero_partial_object(inode, first_object_set + 
i*stripe_width, &len);
+				if (ret)
+					goto out;
+			}
+		}
+		for (i = first_object_set; i < last_object_set; i += object_set_size) {
+			for (j = i; j < i + stripe_width; j += stripe_unit_size) {
+				/* skip the very first object */
+				if (j == 0)
+					continue;
+				ret = ceph_delete_object(inode, j, &len);
+				/* object already deleted */
+				if (ret == -ENOENT)
+					ret = 0;
+				if (ret)
+					goto out;
+			}
+		}
+	}
+
+	/* deal with the object set contains the start or the end of the hole */
+	if (first_object_set - offset > 0) {
+		ret = ceph_zero_partial_object_set(inode, offset, first_object_set - 1);
+		if (ret)
+			goto out;
+	}
+	if (offset + length - last_object_set > 0) {
+		ret = ceph_zero_partial_object_set(inode, last_object_set, offset + 
length - 1);
+	}
+	
+	out:
+	if (ret == 0) {
+		spin_lock(&ci->i_ceph_lock);
+		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
+		spin_unlock(&ci->i_ceph_lock);
+		if (dirty)
+			__mark_inode_dirty(inode, dirty);
+	}
+	ceph_put_cap_refs(ci, got);
+	return ret;
+}
+
+static int ceph_punch_hole(struct file *file, loff_t offset, loff_t length)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	int ret = 0;
+
+    if (!S_ISREG(inode->i_mode)) {
+        return -EOPNOTSUPP;
+	}
+	if (IS_SWAPFILE(inode)) {
+		return -ETXTBSY;
+	}
+	mutex_lock(&inode->i_mutex);
+
+	/* No need to punch hole beyond i_size */
+	if (offset >= inode->i_size)
+		goto out_unlock;
+
+	/*
+	 * If the hole extends beyond i_size, set the hole
+	 * to end after the page that contains i_size
+	 */
+	if (offset + length > inode->i_size) {
+		length = inode->i_size +
+		   PAGE_CACHE_SIZE - (inode->i_size & (PAGE_CACHE_SIZE - 1)) -
+		   offset;
+	}
+
+	ceph_truncate_and_zero_page_cache(inode, offset, length);
+	ret = ceph_delete_and_zero_objects(file, offset, length);
+	
+	out_unlock:
+	mutex_unlock(&inode->i_mutex);
+	return ret;
+}
+
+static long ceph_fallocate(struct file *file, int mode, loff_t offset, 
loff_t length)
+{
+	/* FALLOC_FL_PUNCH_HOLE must be used with FALLOC_FL_KEEP_SIZE */
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+		return -EOPNOTSUPP;
+	if (mode & FALLOC_FL_PUNCH_HOLE)
+		return ceph_punch_hole(file, offset, length);
+	return -EOPNOTSUPP;
+}
+
  const struct file_operations ceph_file_fops = {
  	.open = ceph_open,
  	.release = ceph_release,
@@ -898,5 +1210,6 @@ const struct file_operations ceph_file_fops = {
  	.splice_write = generic_file_splice_write,
  	.unlocked_ioctl = ceph_ioctl,
  	.compat_ioctl	= ceph_ioctl,
+	.fallocate = ceph_fallocate,
  };

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 3a246a6..a6d9671 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -503,7 +503,8 @@ void osd_req_op_extent_init(struct ceph_osd_request 
*osd_req,
  	struct ceph_osd_req_op *op = _osd_req_op_init(osd_req, which, opcode);
  	size_t payload_len = 0;

-	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE);
+	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
+			opcode != CEPH_OSD_OP_DELETE && opcode != CEPH_OSD_OP_ZERO);

  	op->extent.offset = offset;
  	op->extent.length = length;
@@ -631,6 +632,8 @@ static u64 osd_req_encode_op(struct ceph_osd_request 
*req,
  		break;
  	case CEPH_OSD_OP_READ:
  	case CEPH_OSD_OP_WRITE:
+	case CEPH_OSD_OP_DELETE:
+	case CEPH_OSD_OP_ZERO:
  		if (src->op == CEPH_OSD_OP_WRITE)
  			request_data_len = src->extent.length;
  		dst->extent.offset = cpu_to_le64(src->extent.offset);
@@ -715,7 +718,8 @@ struct ceph_osd_request 
*ceph_osdc_new_request(struct ceph_osd_client *osdc,
  	u64 object_base;
  	int r;

-	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE);
+	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
+			opcode != CEPH_OSD_OP_DELETE && opcode != CEPH_OSD_OP_ZERO);

  	req = ceph_osdc_alloc_request(osdc, snapc, num_ops, use_mempool,
  					GFP_NOFS);
-- 
1.7.9.5