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| author | Darrick J. Wong <darrick.wong@oracle.com> | 2018-06-22 09:26:56 +0300 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2018-06-24 21:56:36 +0300 |
| commit | aafe12cee0b132824f5187987f8a3fb704b9f685 (patch) | |
| tree | b8a63a10619de108ad967af566a1846de4f0bf42 /fs/xfs | |
| parent | 10ee25268e1f8475905e1deb85bb83627dca561e (diff) | |
| download | linux-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/xfs')
| -rw-r--r-- | fs/xfs/xfs_fsops.c | 2 |
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; |