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authorDarrick J. Wong <darrick.wong@oracle.com>2018-06-22 09:26:56 +0300
committerDarrick J. Wong <darrick.wong@oracle.com>2018-06-24 21:56:36 +0300
commitaafe12cee0b132824f5187987f8a3fb704b9f685 (patch)
treeb8a63a10619de108ad967af566a1846de4f0bf42 /fs
parent10ee25268e1f8475905e1deb85bb83627dca561e (diff)
downloadlinux-aafe12cee0b132824f5187987f8a3fb704b9f685.tar.xz
xfs: don't trip over negative free space in xfs_reserve_blocks
If we somehow end up with a filesystem that has fewer free blocks than the blocks set aside to avoid ENOSPC deadlocks, it's possible that the free space calculation in xfs_reserve_blocks will spit out a negative number (because percpu_counter_sum returns s64). We fail to notice this negative number and set fdblks_delta to it. Now we increment fdblocks(!) and the unsigned type of m_resblks means that we end up setting a ridiculously huge m_resblks reservation. Avoid this comedy of errors by detecting the negative free space and returning -ENOSPC. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Allison Henderson <allison.henderson@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs')
-rw-r--r--fs/xfs/xfs_fsops.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index a7afcad6b711..3f2bd6032cf8 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -387,7 +387,7 @@ xfs_reserve_blocks(
do {
free = percpu_counter_sum(&mp->m_fdblocks) -
mp->m_alloc_set_aside;
- if (!free)
+ if (free <= 0)
break;
delta = request - mp->m_resblks;