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);
 }