Construct an img like this: dd if=/dev/zero of=xfs.img bs=1M count=20 mkfs.xfs -d agcount=1 xfs.img xfs_db -x xfs.img sb 0 write fdblocks 0 agf 0 write freeblks 0 write longest 0 quit mount it, df -h /mnt(xfs mount point), will show this: Filesystem Size Used Avail Use% Mounted on /dev/loop0 17M -64Z -32K 100% /mnt Reported-by: Hulk Robot <hulkci@xxxxxxxxxx> Signed-off-by: Zheng Bin <zhengbin13@xxxxxxxxxx> --- fs/xfs/xfs_super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index e80bd2c4c279..aae469f73efe 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -807,7 +807,8 @@ xfs_fs_statfs( statp->f_blocks = sbp->sb_dblocks - lsize; spin_unlock(&mp->m_sb_lock); - statp->f_bfree = fdblocks - mp->m_alloc_set_aside; + /* make sure statp->f_bfree does not underflow */ + statp->f_bfree = max_t(int64_t, fdblocks - mp->m_alloc_set_aside, 0); statp->f_bavail = statp->f_bfree; fakeinos = XFS_FSB_TO_INO(mp, statp->f_bfree); -- 2.26.0.106.g9fadedd
