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>
1 file changed