[PATCH 6/6] xfs: lock the healthmon when inserting unmount event

["Darrick J. Wong" <djwong@kernel.org>]

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

LOLLM complains that xfs_healthmon_unmount does an unlocked insert of
the unmount event into the health monitor's event list.  Fix that.

Cc: <stable@vger.kernel.org> # v7.0
Fixes: 25ca57fa3624ca ("xfs: convey filesystem unmount events to the health monitor")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_healthmon.c |    6 ++++++
 1 file changed, 6 insertions(+)


diff --git a/fs/xfs/xfs_healthmon.c b/fs/xfs/xfs_healthmon.c
index 4521ffdab9f1ae..3ae5f4496ad1aa 100644
--- a/fs/xfs/xfs_healthmon.c
+++ b/fs/xfs/xfs_healthmon.c
@@ -272,6 +272,8 @@ __xfs_healthmon_insert(
 {
 	struct timespec64		now;
 
+	lockdep_assert_held(&hm->lock);
+
 	ktime_get_coarse_real_ts64(&now);
 	event->time_ns = (now.tv_sec * NSEC_PER_SEC) + now.tv_nsec;
 
@@ -294,6 +296,8 @@ __xfs_healthmon_push(
 {
 	struct timespec64		now;
 
+	lockdep_assert_held(&hm->lock);
+
 	ktime_get_coarse_real_ts64(&now);
 	event->time_ns = (now.tv_sec * NSEC_PER_SEC) + now.tv_nsec;
 
@@ -415,8 +419,10 @@ xfs_healthmon_unmount(
 	 * There's nothing actionable for userspace after an unmount.  Once
 	 * we've inserted the unmount event, hm no longer owns that event.
 	 */
+	mutex_lock(&hm->lock);
 	__xfs_healthmon_insert(hm, hm->unmount_event);
 	hm->unmount_event = NULL;
+	mutex_unlock(&hm->lock);
 
 	xfs_healthmon_detach(hm);
 	xfs_healthmon_put(hm);