With upcoming lock tracepoints config, it'd allow some lockdep
annotation code without enabling CONFIG_LOCKDEP actually.  In that
config, size of the struct lock_class_key would be 0.

But it'd cause divide-by-zero in btrfs_set_buffer_lockdep_class() due
to ARRAY_SIZE macro.  Let's change it to use ks->names[] instead.  It
should have the same size as with ks->keys[].

Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: David Sterba <dsterba@suse.com>
Cc: linux-btrfs@vger.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 fs/btrfs/disk-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 87a5addbedf6..be41e35bee92 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c

@@ -190,7 +190,7 @@ void btrfs_set_buffer_lockdep_class(u64 objectid, struct extent_buffer *eb,
 {
 	struct btrfs_lockdep_keyset *ks;
 
-	BUG_ON(level >= ARRAY_SIZE(ks->keys));
+	BUG_ON(level >= ARRAY_SIZE(ks->names));
 
 	/* find the matching keyset, id 0 is the default entry */
 	for (ks = btrfs_lockdep_keysets; ks->id; ks++)

-- 
2.35.0.263.gb82422642f-goog