btrfs: use cond_resched_lock where possible

Clean the opencoded variant, cond_resched_lock also checks the lock for
contention so it might help in some cases that were not covered by
simple need_resched().

Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/file.c

@@ -273,11 +273,7 @@ void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
 		defrag = rb_entry(node, struct inode_defrag, rb_node);
 		kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 
-		if (need_resched()) {
-			spin_unlock(&fs_info->defrag_inodes_lock);
-			cond_resched();
-			spin_lock(&fs_info->defrag_inodes_lock);
-		}
+		cond_resched_lock(&fs_info->defrag_inodes_lock);
 
 		node = rb_first(&fs_info->defrag_inodes);
 	}

fs/btrfs/free-space-cache.c

@@ -2402,11 +2402,8 @@ static void __btrfs_remove_free_space_cache_locked(
 		} else {
 			free_bitmap(ctl, info);
 		}
-		if (need_resched()) {
-			spin_unlock(&ctl->tree_lock);
-			cond_resched();
-			spin_lock(&ctl->tree_lock);
-		}
+
+		cond_resched_lock(&ctl->tree_lock);
 	}
 }
 
@@ -2431,11 +2428,8 @@ void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
 
 		WARN_ON(cluster->block_group != block_group);
 		__btrfs_return_cluster_to_free_space(block_group, cluster);
-		if (need_resched()) {
-			spin_unlock(&ctl->tree_lock);
-			cond_resched();
-			spin_lock(&ctl->tree_lock);
-		}
+
+		cond_resched_lock(&ctl->tree_lock);
 	}
 	__btrfs_remove_free_space_cache_locked(ctl);
 	spin_unlock(&ctl->tree_lock);

fs/btrfs/transaction.c

@@ -93,11 +93,8 @@ static void clear_btree_io_tree(struct extent_io_tree *tree)
 		 */
 		ASSERT(!waitqueue_active(&state->wq));
 		free_extent_state(state);
-		if (need_resched()) {
-			spin_unlock(&tree->lock);
-			cond_resched();
-			spin_lock(&tree->lock);
-		}
+
+		cond_resched_lock(&tree->lock);
 	}
 	spin_unlock(&tree->lock);
 }