From a2b1693bac45ea3fe3ba612fd22c45f17449f610 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 13 Apr 2012 13:11:33 -0700 Subject: blkcg: implement per-queue policy activation All blkcg policies were assumed to be enabled on all request_queues. Due to various implementation obstacles, during the recent blkcg core updates, this was temporarily implemented as shooting down all !root blkgs on elevator switch and policy [de]registration combined with half-broken in-place root blkg updates. In addition to being buggy and racy, this meant losing all blkcg configurations across those events. Now that blkcg is cleaned up enough, this patch replaces the temporary implementation with proper per-queue policy activation. Each blkcg policy should call the new blkcg_[de]activate_policy() to enable and disable the policy on a specific queue. blkcg_activate_policy() allocates and installs policy data for the policy for all existing blkgs. blkcg_deactivate_policy() does the reverse. If a policy is not enabled for a given queue, blkg printing / config functions skip the respective blkg for the queue. blkcg_activate_policy() also takes care of root blkg creation, and cfq_init_queue() and blk_throtl_init() are updated accordingly. This replaces blkcg_bypass_{start|end}() and update_root_blkg_pd() unnecessary. Dropped. v2: cfq_init_queue() was returning uninitialized @ret on root_group alloc failure if !CONFIG_CFQ_GROUP_IOSCHED. Fixed. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- block/elevator.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'block/elevator.c') diff --git a/block/elevator.c b/block/elevator.c index be3ab6df0fea..6a55d418896f 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -896,8 +896,6 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) ioc_clear_queue(q); spin_unlock_irq(q->queue_lock); - blkg_destroy_all(q, false); - /* allocate, init and register new elevator */ err = -ENOMEM; q->elevator = elevator_alloc(q, new_e); -- cgit v1.2.1