blkcg: kill blkio_list and replace blkio_list_lock with a mutex

With blkio_policy[], blkio_list is redundant and hinders with
per-queue policy activation.  Remove it.  Also, replace
blkio_list_lock with a mutex blkcg_pol_mutex and let it protect the
whole [un]registration.

This is to prepare for per-queue policy activation and doesn't cause
any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 0 insertions, 1 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 64392ac76ce8..c772581c9011 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -102,7 +102,6 @@ struct blkio_policy_ops {
 };
 
 struct blkio_policy_type {
-        struct list_head list;
         struct blkio_policy_ops ops;
         enum blkio_policy_id plid;
         size_t pdata_size;              /* policy specific private data size */