Btrfs: fix protection between walking backrefs and root deletion
authorWang Shilong <wangsl.fnst@cn.fujitsu.com>
Thu, 23 Jan 2014 05:47:48 +0000 (13:47 +0800)
committerChris Mason <clm@fb.com>
Wed, 29 Jan 2014 15:06:23 +0000 (07:06 -0800)
commit538f72cdf03cad1c21c551ea542c8ce7d9fa2d81
treed4480e764bdebea4cac696ffb25f9025c61ea240
parent3c9665df0c5d3f471b07efc32181459386678ebd
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>
fs/btrfs/backref.c