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, 14 insertions, 11 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d02f0ae9637f..08db2fc70c29 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -4157,7 +4157,6 @@ static struct blkio_policy_type blkio_policy_cfq = {
                 .blkio_init_group_fn =          cfq_init_blkio_group,
                 .blkio_reset_group_stats_fn =   cfqg_stats_reset,
         },
-        .plid = BLKIO_POLICY_PROP,
         .pdata_size = sizeof(struct cfq_group),
         .cftypes = cfq_blkcg_files,
 };
@@ -4181,27 +4180,31 @@ static int __init cfq_init(void)
 #else
                 cfq_group_idle = 0;
 #endif
+
+        ret = blkio_policy_register(&blkio_policy_cfq);
+        if (ret)
+                return ret;
+
         cfq_pool = KMEM_CACHE(cfq_queue, 0);
         if (!cfq_pool)
-                return -ENOMEM;
+                goto err_pol_unreg;
 
         ret = elv_register(&iosched_cfq);
-        if (ret) {
-                kmem_cache_destroy(cfq_pool);
-                return ret;
-        }
+        if (ret)
+                goto err_free_pool;
 
-#ifdef CONFIG_CFQ_GROUP_IOSCHED
-        blkio_policy_register(&blkio_policy_cfq);
-#endif
         return 0;
+
+err_free_pool:
+        kmem_cache_destroy(cfq_pool);
+err_pol_unreg:
+        blkio_policy_unregister(&blkio_policy_cfq);
+        return ret;
 }
 
 static void __exit cfq_exit(void)
 {
-#ifdef CONFIG_CFQ_GROUP_IOSCHED
         blkio_policy_unregister(&blkio_policy_cfq);
-#endif
         elv_unregister(&iosched_cfq);
         kmem_cache_destroy(cfq_pool);
 }