Commit e0d76fa4 authored by Brian Foster's avatar Brian Foster Committed by Darrick J. Wong

xfs: prevent quotacheck from overloading inode lru

Quotacheck runs at mount time in situations where quota accounting must
be recalculated. In doing so, it uses bulkstat to visit every inode in
the filesystem. Historically, every inode processed during quotacheck
was released and immediately tagged for reclaim because quotacheck runs
before the superblock is marked active by the VFS. In other words,
the final iput() lead to an immediate ->destroy_inode() call, which
allowed the XFS background reclaim worker to start reclaiming inodes.

Commit 17c12bcd ("xfs: when replaying bmap operations, don't let
unlinked inodes get reaped") marks the XFS superblock active sooner as
part of the mount process to support caching inodes processed during log
recovery. This occurs before quotacheck and thus means all inodes
processed by quotacheck are inserted to the LRU on release.  The
s_umount lock is held until the mount has completed and thus prevents
the shrinkers from operating on the sb. This means that quotacheck can
excessively populate the inode LRU and lead to OOM conditions on systems
without sufficient RAM.

Update the quotacheck bulkstat handler to set XFS_IGET_DONTCACHE on
inodes processed by quotacheck. This causes ->drop_inode() to return 1
and in turn causes iput_final() to evict the inode. This preserves the
original quotacheck behavior and prevents it from overloading the LRU
and running out of memory.

CC: stable@vger.kernel.org # v4.9
Reported-by: default avatarMartin Svec <martin.svec@zoner.cz>
Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarEric Sandeen <sandeen@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent c364b6d0
...@@ -1177,7 +1177,8 @@ xfs_qm_dqusage_adjust( ...@@ -1177,7 +1177,8 @@ xfs_qm_dqusage_adjust(
* the case in all other instances. It's OK that we do this because * the case in all other instances. It's OK that we do this because
* quotacheck is done only at mount time. * quotacheck is done only at mount time.
*/ */
error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_EXCL, &ip); error = xfs_iget(mp, NULL, ino, XFS_IGET_DONTCACHE, XFS_ILOCK_EXCL,
&ip);
if (error) { if (error) {
*res = BULKSTAT_RV_NOTHING; *res = BULKSTAT_RV_NOTHING;
return error; return error;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment