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Commit da8b0662 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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blkcg: make blkg_conf_prep() take @pol and return with queue lock held 



Add @pol to blkg_conf_prep() and let it return with queue lock held
(to be released by blkg_conf_finish()).  Note that @pol isn't used
yet.

This is to prepare for per-queue policy activation and doesn't cause
any visible difference.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8bd435b3

block/blk-cgroup.c

+10 −7
Original line number Diff line number Diff line
@@ -464,17 +464,19 @@ EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); 
/**

 * blkg_conf_prep - parse and prepare for per-blkg config update

 * @blkcg: target block cgroup

 * @pol: target policy

 * @input: input string

 * @ctx: blkg_conf_ctx to be filled

 *

 * Parse per-blkg config update from @input and initialize @ctx with the

 * result.  @ctx->blkg points to the blkg to be updated and @ctx->v the new

 * value.  This function returns with RCU read locked and must be paired

 * with blkg_conf_finish().

 * value.  This function returns with RCU read lock and queue lock held and

 * must be paired with blkg_conf_finish().

 */

int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input,

int blkg_conf_prep(struct blkio_cgroup *blkcg,

		   const struct blkio_policy_type *pol, const char *input,

		   struct blkg_conf_ctx *ctx)

	__acquires(rcu)

	__acquires(rcu) __acquires(disk->queue->queue_lock)

{

	struct gendisk *disk;

	struct blkio_group *blkg;
@@ -490,14 +492,14 @@ int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input, 
		return -EINVAL;



	rcu_read_lock();



	spin_lock_irq(disk->queue->queue_lock);



	blkg = blkg_lookup_create(blkcg, disk->queue, false);

	spin_unlock_irq(disk->queue->queue_lock);



	if (IS_ERR(blkg)) {

		ret = PTR_ERR(blkg);

		rcu_read_unlock();

		spin_unlock_irq(disk->queue->queue_lock);

		put_disk(disk);

		/*

		 * If queue was bypassing, we should retry.  Do so after a
@@ -527,8 +529,9 @@ EXPORT_SYMBOL_GPL(blkg_conf_prep); 
 * with blkg_conf_prep().

 */

void blkg_conf_finish(struct blkg_conf_ctx *ctx)

	__releases(rcu)

	__releases(ctx->disk->queue->queue_lock) __releases(rcu)

{

	spin_unlock_irq(ctx->disk->queue->queue_lock);

	rcu_read_unlock();

	put_disk(ctx->disk);

}

block/blk-cgroup.h

+2 −1
Original line number Diff line number Diff line
@@ -128,7 +128,8 @@ struct blkg_conf_ctx { 
	u64			v;

};



int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input,

int blkg_conf_prep(struct blkio_cgroup *blkcg,

		   const struct blkio_policy_type *pol, const char *input,

		   struct blkg_conf_ctx *ctx);

void blkg_conf_finish(struct blkg_conf_ctx *ctx);

block/blk-throttle.c

+1 −1
Original line number Diff line number Diff line
@@ -993,7 +993,7 @@ static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf, 
	struct throtl_grp *tg;

	int ret;



	ret = blkg_conf_prep(blkcg, buf, &ctx);

	ret = blkg_conf_prep(blkcg, &blkio_policy_throtl, buf, &ctx);

	if (ret)

		return ret;

block/cfq-iosched.c

+1 −1
Original line number Diff line number Diff line
@@ -1400,7 +1400,7 @@ static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft, 
	struct cfq_group *cfqg;

	int ret;



	ret = blkg_conf_prep(blkcg, buf, &ctx);

	ret = blkg_conf_prep(blkcg, &blkio_policy_cfq, buf, &ctx);

	if (ret)

		return ret;