xfs: fix unsigned underflow in xfs_free_eofblocks
map_len is unsigned. Checking map_len <= 0 is buggy when it should be
below zero. So, check exact expression instead of map_len.
Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 9865e11..3ac137d 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -589,9 +589,9 @@
*/
end_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)ip->i_size));
last_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
- map_len = last_fsb - end_fsb;
- if (map_len <= 0)
+ if (last_fsb <= end_fsb)
return 0;
+ map_len = last_fsb - end_fsb;
nimaps = 1;
xfs_ilock(ip, XFS_ILOCK_SHARED);