Btrfs: fix wrong search path initialization before searching tree root

To search tree root without transaction protection, we should neither search commit
root nor skip locking here, fix it.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 84aed2f..aa60cbe 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -2095,7 +2095,7 @@
 	char *name = NULL;
 	int namelen;
 
-	path = alloc_path_for_send();
+	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;