blkcg: remove static policy ID enums

Remove BLKIO_POLICY_* enums and let blkio_policy_register() allocate
@pol->plid dynamically on registration.  The maximum number of blkcg
policies which can be registered at the same time is defined by
BLKCG_MAX_POLS constant added to include/linux/blkdev.h.

Note that blkio_policy_register() now may fail.  Policy init functions
updated accordingly and unnecessary ifdefs removed from cfq_init().

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, 1 insertions, 3 deletions

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 07c17c27a628..0dc4645aa7fe 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1089,7 +1089,6 @@ static struct blkio_policy_type blkio_policy_throtl = {
                 .blkio_exit_group_fn = throtl_exit_blkio_group,
                 .blkio_reset_group_stats_fn = throtl_reset_group_stats,
         },
-        .plid = BLKIO_POLICY_THROTL,
         .pdata_size = sizeof(struct throtl_grp),
         .cftypes = throtl_files,
 };
@@ -1271,8 +1270,7 @@ static int __init throtl_init(void)
         if (!kthrotld_workqueue)
                 panic("Failed to create kthrotld\n");
 
-        blkio_policy_register(&blkio_policy_throtl);
-        return 0;
+        return blkio_policy_register(&blkio_policy_throtl);
 }
 
 module_init(throtl_init);