| Message ID | 22a11e65fd5037498a78de61f3ed4dae466ad854.1489791330.git.calvinowens@fb.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 35703a8..da7cd27 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -58,6 +58,17 @@ xfs_zero_range( xfs_off_t count, bool *did_zero) { + /* + * Avoid doing I/O beyond eof - it's not necessary + * since nothing can read beyond eof. The space will + * be zeroed when the file is extended anyway. + */ + if (pos >= XFS_ISIZE(ip)) + return 0; + + if ((pos + count) >= XFS_ISIZE(ip)) + count = XFS_ISIZE(ip) - pos - 1; + return iomap_zero_range(VFS_I(ip), pos, count, NULL, &xfs_iomap_ops); }
Commit 3c2bdc912a1cc050 ("xfs: kill xfs_zero_remaining_bytes") replaced xfs_zero_remaining_bytes() with calls to iomap helpers. Unfortunately the new iomap helpers don't enforce that [pos,count) lies strictly on [0,i_size). This causes fallocate(mode=PUNCH_HOLE|KEEP_SIZE) calls touching [i_size & ~PAGE_MASK, OFF_T_MAX] to round i_size up to the nearest multiple of PAGE_SIZE: calvinow@vm-disks/generic-xfs-1 ~$ dd if=/dev/urandom of=test bs=2048 count=1 calvinow@vm-disks/generic-xfs-1 ~$ stat test Size: 2048 Blocks: 8 IO Block: 4096 regular file calvinow@vm-disks/generic-xfs-1 ~$ fallocate -n -l 2048 -o 2048 -p test calvinow@vm-disks/generic-xfs-1 ~$ stat test Size: 4096 Blocks: 8 IO Block: 4096 regular file Fix this by reintroducing the checks xfs_zero_remaining_bytes() did against i_size into xfs_zero_range(). Reported-by: Aaron Gao <gzh@fb.com> Fixes: 3c2bdc912a1cc050 ("xfs: kill xfs_zero_remaining_bytes") Cc: Christoph Hellwig <hch@lst.de> Cc: <stable@vger.kernel.org> # 4.8+ Signed-off-by: Calvin Owens <calvinowens@fb.com> --- fs/xfs/xfs_file.c | 11 +++++++++++ 1 file changed, 11 insertions(+)