[PATCH 3/3] xfs: force log and push AIL to clear pinned inodes when aborting mount

From: "Darrick J. Wong" <djwong@kernel.org>
To: djwong@kernel.org
Cc: linux-xfs@vger.kernel.org, hch@lst.de, dchinner@redhat.com,
	christian.brauner@ubuntu.com
Subject: [PATCH 3/3] xfs: force log and push AIL to clear pinned inodes when aborting mount
Date: Tue, 02 Mar 2021 14:28:34 -0800	[thread overview]
Message-ID: <161472411392.3421449.548910053179741704.stgit@magnolia> (raw)
In-Reply-To: <161472409643.3421449.2100229515469727212.stgit@magnolia>

From: Darrick J. Wong <djwong@kernel.org>

If we allocate quota inodes in the process of mounting a filesystem but
then decide to abort the mount, it's possible that the quota inodes are
sitting around pinned by the log.  Now that inode reclaim relies on the
AIL to flush inodes, we have to force the log and push the AIL in
between releasing the quota inodes and kicking off reclaim to tear down
all the incore inodes.

This was originally found during a fuzz test of metadata directories
(xfs/1546), but the actual symptom was that reclaim hung up on the quota
inodes.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_mount.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 52370d0a3f43..6f445b611663 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1007,6 +1007,16 @@ xfs_mountfs(
 	xfs_irele(rip);
 	/* Clean out dquots that might be in memory after quotacheck. */
 	xfs_qm_unmount(mp);
+
+	/*
+	 * It's possible that we modified some inodes as part of setting up
+	 * quotas or initializing filesystem metadata.  These inodes could be
+	 * pinned in the log, so force the log and push the AIL to unpin them
+	 * so that we can reclaim them.
+	 */
+	xfs_log_force(mp, XFS_LOG_SYNC);
+	xfs_ail_push_all_sync(mp->m_ail);
+
 	/*
 	 * Cancel all delayed reclaim work and reclaim the inodes directly.
 	 * We have to do this /after/ rtunmount and qm_unmount because those

