Btrfs: pass delayed_refs directly to btrfs_find_delayed_ref_head

All we need is @delayed_refs, all callers have get it ahead of calling
btrfs_find_delayed_ref_head since lock needs to be acquired firstly,
there is no reason to deference it again inside the function.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/backref.c

@@ -1284,7 +1284,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
 		 */
 		delayed_refs = &trans->transaction->delayed_refs;
 		spin_lock(&delayed_refs->lock);
-		head = btrfs_find_delayed_ref_head(trans, bytenr);
+		head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
 		if (head) {
 			if (!mutex_trylock(&head->mutex)) {
 				atomic_inc(&head->node.refs);

fs/btrfs/delayed-ref.c

@@ -909,11 +909,8 @@ int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
  * the head node if any where found, or NULL if not.
  */
 struct btrfs_delayed_ref_head *
-btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
+btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 bytenr)
 {
-	struct btrfs_delayed_ref_root *delayed_refs;
-
-	delayed_refs = &trans->transaction->delayed_refs;
 	return find_ref_head(&delayed_refs->href_root, bytenr, 0);
 }
 

fs/btrfs/delayed-ref.h

@@ -261,7 +261,8 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 			      struct btrfs_delayed_ref_head *head);
 
 struct btrfs_delayed_ref_head *
-btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
+btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
+			    u64 bytenr);
 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 			   struct btrfs_delayed_ref_head *head);
 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)

fs/btrfs/extent-tree.c

@@ -888,7 +888,7 @@ int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
 
 	delayed_refs = &trans->transaction->delayed_refs;
 	spin_lock(&delayed_refs->lock);
-	head = btrfs_find_delayed_ref_head(trans, bytenr);
+	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
 	if (head) {
 		if (!mutex_trylock(&head->mutex)) {
 			atomic_inc(&head->node.refs);
@@ -3041,7 +3041,7 @@ static noinline int check_delayed_ref(struct btrfs_trans_handle *trans,
 
 	delayed_refs = &trans->transaction->delayed_refs;
 	spin_lock(&delayed_refs->lock);
-	head = btrfs_find_delayed_ref_head(trans, bytenr);
+	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
 	if (!head) {
 		spin_unlock(&delayed_refs->lock);
 		return 0;
@@ -7091,7 +7091,7 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
 
 	delayed_refs = &trans->transaction->delayed_refs;
 	spin_lock(&delayed_refs->lock);
-	head = btrfs_find_delayed_ref_head(trans, bytenr);
+	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
 	if (!head)
 		goto out_delayed_unlock;