Btrfs: introduce per-subvolume ordered extent list

The reason we introduce per-subvolume ordered extent list is the same
as the per-subvolume delalloc inode list.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 18191f1..5152075 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7991,9 +7991,9 @@
 	 */
 	smp_mb();
 	if (!list_empty(&BTRFS_I(inode)->ordered_operations)) {
-		spin_lock(&root->fs_info->ordered_extent_lock);
+		spin_lock(&root->fs_info->ordered_root_lock);
 		list_del_init(&BTRFS_I(inode)->ordered_operations);
-		spin_unlock(&root->fs_info->ordered_extent_lock);
+		spin_unlock(&root->fs_info->ordered_root_lock);
 	}
 
 	if (test_bit(BTRFS_INODE_HAS_ORPHAN_ITEM,