From: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Date: Thu, 23 Jan 2014 05:47:48 +0000 (+0800)
Subject: Btrfs: fix protection between walking backrefs and root deletion
X-Git-Tag: v3.14-rc1~29^2~11
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=538f72cdf03cad1c21c551ea542c8ce7d9fa2d81;p=pandora-kernel.git

Btrfs: fix protection between walking backrefs and root deletion

There is a race condition between resolving indirect ref and root deletion,
and we should gurantee that root can not be destroyed to avoid accessing
broken tree here.

Here we fix it by holding @subvol_srcu, and we will release it as soon
as we have held root node lock.

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>
---

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