btrfs: add a helper to return a head ref

Simplify the error handling in __btrfs_run_delayed_refs by breaking out
the code used to return a head back to the delayed_refs tree for
processing into a helper function.
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

@@ -2575,6 +2575,16 @@ select_delayed_ref(struct btrfs_delayed_ref_head *head)
 	return ref;
 }
 
+static void unselect_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
+				      struct btrfs_delayed_ref_head *head)
+{
+	spin_lock(&delayed_refs->lock);
+	head->processing = 0;
+	delayed_refs->num_heads_ready++;
+	spin_unlock(&delayed_refs->lock);
+	btrfs_delayed_ref_unlock(head);
+}
+
 /*
  * Returns 0 on success or if called with an already aborted transaction.
  * Returns -ENOMEM or -EIO on failure and will abort the transaction.
@@ -2648,11 +2658,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 		if (ref && ref->seq &&
 		    btrfs_check_delayed_seq(fs_info, delayed_refs, ref->seq)) {
 			spin_unlock(&locked_ref->lock);
-			spin_lock(&delayed_refs->lock);
-			locked_ref->processing = 0;
-			delayed_refs->num_heads_ready++;
-			spin_unlock(&delayed_refs->lock);
-			btrfs_delayed_ref_unlock(locked_ref);
+			unselect_delayed_ref_head(delayed_refs, locked_ref);
 			locked_ref = NULL;
 			cond_resched();
 			count++;
@@ -2698,14 +2704,11 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 					 */
 					if (must_insert_reserved)
 						locked_ref->must_insert_reserved = 1;
-					spin_lock(&delayed_refs->lock);
-					locked_ref->processing = 0;
-					delayed_refs->num_heads_ready++;
-					spin_unlock(&delayed_refs->lock);
+					unselect_delayed_ref_head(delayed_refs,
+								  locked_ref);
 					btrfs_debug(fs_info,
 						    "run_delayed_extent_op returned %d",
 						    ret);
-					btrfs_delayed_ref_unlock(locked_ref);
 					return ret;
 				}
 				continue;
@@ -2763,11 +2766,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 
 		btrfs_free_delayed_extent_op(extent_op);
 		if (ret) {
-			spin_lock(&delayed_refs->lock);
-			locked_ref->processing = 0;
-			delayed_refs->num_heads_ready++;
-			spin_unlock(&delayed_refs->lock);
-			btrfs_delayed_ref_unlock(locked_ref);
+			unselect_delayed_ref_head(delayed_refs, locked_ref);
 			btrfs_put_delayed_ref(ref);
 			btrfs_debug(fs_info, "run_one_delayed_ref returned %d",
 				    ret);