btrfs: comment waitqueue_active implied by locks
Suggested-by: Chris Mason <clm@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index fcf7265..1a33d3e 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -810,7 +810,11 @@
}
goto done_nolock;
- } else if (waitqueue_active(&h->wait)) {
+ /*
+ * The barrier for this waitqueue_active is not needed,
+ * we're protected by h->lock and can't miss a wakeup.
+ */
+ } else if (waitqueue_active(&h->wait)) {
spin_unlock(&rbio->bio_list_lock);
spin_unlock_irqrestore(&h->lock, flags);
wake_up(&h->wait);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 1bbaace..d0deb46 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2950,6 +2950,9 @@
atomic_set(&log_root_tree->log_commit[index2], 0);
mutex_unlock(&log_root_tree->log_mutex);
+ /*
+ * The barrier before waitqueue_active is implied by mutex_unlock
+ */
if (waitqueue_active(&log_root_tree->log_commit_wait[index2]))
wake_up(&log_root_tree->log_commit_wait[index2]);
out:
@@ -2961,6 +2964,9 @@
atomic_set(&root->log_commit[index1], 0);
mutex_unlock(&root->log_mutex);
+ /*
+ * The barrier before waitqueue_active is implied by mutex_unlock
+ */
if (waitqueue_active(&root->log_commit_wait[index1]))
wake_up(&root->log_commit_wait[index1]);
return ret;