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, 6 insertions, 1 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 33f1b29e53f4..d2c69f8c188a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -35,6 +35,12 @@ struct bsg_job;
 #define BLKDEV_MIN_RQ   4
 #define BLKDEV_MAX_RQ   128     /* Default maximum */
 
+/*
+ * Maximum number of blkcg policies allowed to be registered concurrently.
+ * Defined here to simplify include dependency.
+ */
+#define BLKCG_MAX_POLS          2
+
 struct request;
 typedef void (rq_end_io_fn)(struct request *, int);
 
@@ -363,7 +369,6 @@ struct request_queue {
 
         struct list_head        icq_list;
 #ifdef CONFIG_BLK_CGROUP
-        /* XXX: array size hardcoded to avoid include dependency (temporary) */
         struct list_head        blkg_list;
 #endif