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| author | Qu Wenruo <quwenruo@cn.fujitsu.com> | 2015-10-14 09:26:13 +0200 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2015-10-21 04:07:29 +0200 |
| commit | 0f6925fa2907df58496cabc33fa4677c635e2223 (patch) | |
| tree | 85b4f57ea06fb3f0b0cbb50412742d64719defbb | |
| parent | btrfs: fix use after free iterating extrefs (diff) | |
| download | linux-0f6925fa2907df58496cabc33fa4677c635e2223.tar.xz linux-0f6925fa2907df58496cabc33fa4677c635e2223.zip | |
btrfs: Avoid truncate tailing page if fallocate range doesn't exceed inode size
Current code will always truncate tailing page if its alloc_start is
smaller than inode size.
For example, the file extent layout is like:
0 4K 8K 16K 32K
|<-----Extent A---------------->|
|<--Inode size: 18K---------->|
But if calling fallocate even for range [0,4K), it will cause btrfs to
re-truncate the range [16,32K), causing COW and a new extent.
0 4K 8K 16K 32K
|///////| <- Fallocate call range
|<-----Extent A-------->|<--B-->|
The cause is quite easy, just a careless btrfs_truncate_inode() in a
else branch without extra judgment.
Fix it by add judgment on whether the fallocate range is beyond isize.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
| -rw-r--r-- | fs/btrfs/file.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index b823fac91c92..8c6f247ba81d 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -2584,7 +2584,7 @@ static long btrfs_fallocate(struct file *file, int mode, alloc_start); if (ret) goto out; - } else { + } else if (offset + len > inode->i_size) { /* * If we are fallocating from the end of the file onward we * need to zero out the end of the page if i_size lands in the |