commit 538f72cdf03cad1c21c551ea542c8ce7d9fa2d81
author Wang Shilong <wangsl.fnst@cn.fujitsu.com> Thu Jan 23 13:47:48 2014 +0800
committer Chris Mason <clm@fb.com> Wed Jan 29 07:06:23 2014 -0800
tree d4480e764bdebea4cac696ffb25f9025c61ea240
parent 3c9665df0c5d3f471b07efc32181459386678ebd

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>