[PATCH 5.15 4/6] xfs: check that per-cpu inodegc workers actually run on that cpu

[Leah Rumancik <leah.rumancik@gmail.com>]

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

[ Upstream commit b37c4c8339cd394ea6b8b415026603320a185651 ]

Now that we've allegedly worked out the problem of the per-cpu inodegc
workers being scheduled on the wrong cpu, let's put in a debugging knob
to let us know if a worker ever gets mis-scheduled again.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_icache.c | 2 ++
 fs/xfs/xfs_mount.h  | 3 +++
 fs/xfs/xfs_super.c  | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index ab8181f8d08a..02022164772d 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1856,6 +1856,8 @@ xfs_inodegc_worker(
 	struct llist_node	*node = llist_del_all(&gc->list);
 	struct xfs_inode	*ip, *n;
 
+	ASSERT(gc->cpu == smp_processor_id());
+
 	WRITE_ONCE(gc->items, 0);
 
 	if (!node)
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 3d58938a6f75..29f35169bf9c 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -66,6 +66,9 @@ struct xfs_inodegc {
 	/* approximate count of inodes in the list */
 	unsigned int		items;
 	unsigned int		shrinker_hits;
+#if defined(DEBUG) || defined(XFS_WARN)
+	unsigned int		cpu;
+#endif
 };
 
 /*
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 9b3af7611eaa..569960e4ea3a 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1062,6 +1062,9 @@ xfs_inodegc_init_percpu(
 
 	for_each_possible_cpu(cpu) {
 		gc = per_cpu_ptr(mp->m_inodegc, cpu);
+#if defined(DEBUG) || defined(XFS_WARN)
+		gc->cpu = cpu;
+#endif
 		init_llist_head(&gc->list);
 		gc->items = 0;
 		INIT_DELAYED_WORK(&gc->work, xfs_inodegc_worker);
-- 
2.42.0.515.g380fc7ccd1-goog