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Message-Id: <1304959308-11122-17-git-send-email-amir73il@users.sourceforge.net>
Date: Mon, 9 May 2011 19:41:34 +0300
From: amir73il@...rs.sourceforge.net
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, Amir Goldstein <amir73il@...rs.sf.net>,
Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: [PATCH RFC 16/30] ext4: snapshot block operation - move blocks to snapshot
From: Amir Goldstein <amir73il@...rs.sf.net>
Implementation of moving blocks into a snapshot file.
The move block command maps an allocated blocks to the snapshot file,
allocating only the indirect blocks when needed.
This mechanism is used to move-on-write data blocks to snapshot.
Signed-off-by: Amir Goldstein <amir73il@...rs.sf.net>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
---
fs/ext4/inode.c | 62 +++++++++++++++++++++++++++++++++++++++---------------
1 files changed, 45 insertions(+), 17 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index b930645..c3d4e7a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -676,6 +676,11 @@ static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
new_blocks[index++] = current_block++;
count--;
}
+ if (blks == 0 && target == 0) {
+ /* mapping data blocks */
+ *err = 0;
+ return 0;
+ }
if (count > 0) {
/*
* save the new block number
@@ -777,10 +782,10 @@ failed_out:
* ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
* as described above and return 0.
*/
-static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
- ext4_lblk_t iblock, int indirect_blks,
- int *blks, ext4_fsblk_t goal,
- ext4_lblk_t *offsets, Indirect *branch)
+static int ext4_alloc_branch_cow(handle_t *handle, struct inode *inode,
+ ext4_fsblk_t iblock, int indirect_blks,
+ int *blks, ext4_fsblk_t goal,
+ int *offsets, Indirect *branch, int flags)
{
int blocksize = inode->i_sb->s_blocksize;
int i, n = 0;
@@ -790,6 +795,22 @@ static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
ext4_fsblk_t new_blocks[4];
ext4_fsblk_t current_block;
+ if (SNAPMAP_ISMOVE(flags)) {
+ /* mapping snapshot block to block device block */
+ current_block = SNAPSHOT_BLOCK(iblock);
+ num = 0;
+ if (indirect_blks > 0) {
+ /* allocating only indirect blocks */
+ ext4_alloc_blocks(handle, inode, iblock, goal,
+ indirect_blks, 0, new_blocks, &err);
+ if (err)
+ return err;
+ }
+ /* charge snapshot file owner for moved blocks */
+ dquot_alloc_block_nofail(inode, *blks);
+ num = *blks;
+ new_blocks[indirect_blks] = current_block;
+ } else
num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
*blks, new_blocks, &err);
if (err)
@@ -861,8 +882,11 @@ failed:
}
for (i = n+1; i < indirect_blks; i++)
ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1, 0);
-
- ext4_free_blocks(handle, inode, NULL, new_blocks[i], num, 0);
+ if (SNAPMAP_ISMOVE(flags) && num > 0)
+ /* don't charge snapshot file owner if move failed */
+ dquot_free_block(inode, num);
+ else if (num > 0)
+ ext4_free_blocks(handle, inode, NULL, new_blocks[i], num, 0);
return err;
}
@@ -882,9 +906,8 @@ failed:
* inode (->i_blocks, etc.). In case of success we end up with the full
* chain to new block and return 0.
*/
-static int ext4_splice_branch(handle_t *handle, struct inode *inode,
- ext4_lblk_t block, Indirect *where, int num,
- int blks)
+static int ext4_splice_branch_cow(handle_t *handle, struct inode *inode,
+ long block, Indirect *where, int num, int blks, int flags)
{
int i;
int err = 0;
@@ -951,8 +974,12 @@ err_out:
ext4_free_blocks(handle, inode, where[i].bh, 0, 1,
EXT4_FREE_BLOCKS_FORGET);
}
- ext4_free_blocks(handle, inode, NULL, le32_to_cpu(where[num].key),
- blks, 0);
+ if (SNAPMAP_ISMOVE(flags))
+ /* don't charge snapshot file owner if move failed */
+ dquot_free_block(inode, blks);
+ else
+ ext4_free_blocks(handle, inode, NULL,
+ le32_to_cpu(where[num].key), blks, 0);
return err;
}
@@ -1098,9 +1125,11 @@ static int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
/*
* Block out ext4_truncate while we alter the tree
*/
- err = ext4_alloc_branch(handle, inode, map->m_lblk, indirect_blks,
- &count, goal,
- offsets + (partial - chain), partial);
+ err = ext4_alloc_branch_cow(handle, inode, map->m_lblk, indirect_blks,
+ &count, goal, offsets + (partial - chain),
+ partial, flags);
+ if (err)
+ goto cleanup;
if (map->m_flags & EXT4_MAP_REMAP) {
map->m_len = count;
@@ -1126,9 +1155,8 @@ static int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
* credits cannot be returned. Can we handle this somehow? We
* may need to return -EAGAIN upwards in the worst case. --sct
*/
- if (!err)
- err = ext4_splice_branch(handle, inode, map->m_lblk,
- partial, indirect_blks, count);
+ err = ext4_splice_branch_cow(handle, inode, map->m_lblk, partial,
+ indirect_blks, count, flags);
if (err)
goto cleanup;
--
1.7.0.4
--
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