btrfs: add comments to barriers before waitqueue_active
Reduce number of undocumented barriers out there.
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 9f96042..59eb92f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -10363,8 +10363,7 @@
{
percpu_counter_dec(&root->subv_writers->counter);
/*
- * Make sure counter is updated before we wake up
- * waiters.
+ * Make sure counter is updated before we wake up waiters.
*/
smp_mb();
if (waitqueue_active(&root->subv_writers->wait))