From: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Date: Thu, 13 Feb 2014 03:19:47 +0000 (+0800)
Subject: Btrfs: skip locking when searching commit root
X-Git-Tag: v3.15-rc1~23^2~79
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=e84752d434b5cca0869e906e7b94d0531b25c6d3;p=uclinux-h8%2Flinux.git

Btrfs: skip locking when searching commit root

We won't change commit root, skip locking dance with commit root
when walking backrefs, this can speed up btrfs send operations.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
---

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index a88da721dfc5..860f4f22b9b0 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -873,8 +873,10 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
-	if (!trans)
+	if (!trans) {
 		path->search_commit_root = 1;
+		path->skip_locking = 1;
+	}
 
 	/*
 	 * grab both a lock on the path and a lock on the delayed ref head.