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| author | Miao Xie <miaox@cn.fujitsu.com> | 2014-02-27 13:58:04 +0800 |
|---|---|---|
| committer | Josef Bacik <jbacik@fb.com> | 2014-03-10 15:17:00 -0400 |
| commit | c933956ddf80bc455d33cbcf39d35d935daf45a9 (patch) | |
| tree | 0417dba0c65787ad3de69f92563e1824086706a6 | |
| parent | 9c9ca00bd31989f1a3dcbf54e97c979024e44409 (diff) | |
| download | linux-c933956ddf80bc455d33cbcf39d35d935daf45a9.tar.bz2 | |
Btrfs: fix wrong lock range and write size in check_can_nocow()
The write range may not be sector-aligned, for example:
|--------|--------| <- write range, sector-unaligned, size: 2blocks
|--------|--------|--------| <- correct lock range, size: 3blocks
But according to the old code, we used the size of write range to calculate
the lock range directly, not considered the offset, we would get a wrong lock
range:
|--------|--------| <- write range, sector-unaligned, size: 2blocks
|--------|--------| <- wrong lock range, size: 2blocks
And besides that, the old code also had the same problem when calculating
the real write size. Correct them.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
| -rw-r--r-- | fs/btrfs/file.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 31e48b947060..fc2d21b0a022 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1411,7 +1411,7 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos, int ret; lockstart = round_down(pos, root->sectorsize); - lockend = lockstart + round_up(*write_bytes, root->sectorsize) - 1; + lockend = round_up(pos + *write_bytes, root->sectorsize) - 1; while (1) { lock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend); @@ -1434,7 +1434,8 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos, EXTENT_DIRTY | EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0, NULL, GFP_NOFS); - *write_bytes = min_t(size_t, *write_bytes, num_bytes); + *write_bytes = min_t(size_t, *write_bytes , + num_bytes - pos + lockstart); } unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend); |