Btrfs: make delayed ref lock logic more readable

Locking and unlocking delayed ref mutex are in the different functions,
and the name of lock functions is not uniform, so the readability is not
so good, this patch optimizes the lock logic and makes it more readable.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 24 insertions, 18 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 9bd87f0..b4cb818 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2143,7 +2143,6 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
 						      node->num_bytes);
 			}
 		}
-		mutex_unlock(&head->mutex);
 		return ret;
 	}
 
@@ -2258,7 +2257,7 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
 			 * process of being added. Don't run this ref yet.
 			 */
 			list_del_init(&locked_ref->cluster);
-			mutex_unlock(&locked_ref->mutex);
+			btrfs_delayed_ref_unlock(locked_ref);
 			locked_ref = NULL;
 			delayed_refs->num_heads_ready++;
 			spin_unlock(&delayed_refs->lock);
@@ -2297,25 +2296,22 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
 				btrfs_free_delayed_extent_op(extent_op);
 
 				if (ret) {
-					list_del_init(&locked_ref->cluster);
-					mutex_unlock(&locked_ref->mutex);
-
-					printk(KERN_DEBUG "btrfs: run_delayed_extent_op returned %d\n", ret);
+					printk(KERN_DEBUG
+					       "btrfs: run_delayed_extent_op "
+					       "returned %d\n", ret);
 					spin_lock(&delayed_refs->lock);
+					btrfs_delayed_ref_unlock(locked_ref);
 					return ret;
 				}
 
 				goto next;
 			}
-
-			list_del_init(&locked_ref->cluster);
-			locked_ref = NULL;
 		}
 
 		ref->in_tree = 0;
 		rb_erase(&ref->rb_node, &delayed_refs->root);
 		delayed_refs->num_entries--;
-		if (locked_ref) {
+		if (!btrfs_delayed_ref_is_head(ref)) {
 			/*
 			 * when we play the delayed ref, also correct the
 			 * ref_mod on head
@@ -2337,20 +2333,29 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
 		ret = run_one_delayed_ref(trans, root, ref, extent_op,
 					  must_insert_reserved);
 
-		btrfs_put_delayed_ref(ref);
 		btrfs_free_delayed_extent_op(extent_op);
-		count++;
-
 		if (ret) {
-			if (locked_ref) {
-				list_del_init(&locked_ref->cluster);
-				mutex_unlock(&locked_ref->mutex);
-			}
-			printk(KERN_DEBUG "btrfs: run_one_delayed_ref returned %d\n", ret);
+			btrfs_delayed_ref_unlock(locked_ref);
+			btrfs_put_delayed_ref(ref);
+			printk(KERN_DEBUG
+			       "btrfs: run_one_delayed_ref returned %d\n", ret);
 			spin_lock(&delayed_refs->lock);
 			return ret;
 		}
 
+		/*
+		 * If this node is a head, that means all the refs in this head
+		 * have been dealt with, and we will pick the next head to deal
+		 * with, so we must unlock the head and drop it from the cluster
+		 * list before we release it.
+		 */
+		if (btrfs_delayed_ref_is_head(ref)) {
+			list_del_init(&locked_ref->cluster);
+			btrfs_delayed_ref_unlock(locked_ref);
+			locked_ref = NULL;
+		}
+		btrfs_put_delayed_ref(ref);
+		count++;
 next:
 		cond_resched();
 		spin_lock(&delayed_refs->lock);
@@ -2500,6 +2505,7 @@ again:
 
 		ret = run_clustered_refs(trans, root, &cluster);
 		if (ret < 0) {
+			btrfs_release_ref_cluster(&cluster);
 			spin_unlock(&delayed_refs->lock);
 			btrfs_abort_transaction(trans, root, ret);
 			return ret;