Commit 15974993 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

blkcg: make root blkcg allocation use %GFP_KERNEL 



Currently, blkcg_activate_policy() depends on %GFP_ATOMIC allocation
from __blkg_lookup_create() for root blkcg creation.  This could make
policy fail unnecessarily.

Make blkg_alloc() take @gfp_mask, __blkg_lookup_create() take an
optional @new_blkg for preallocated blkg, and blkcg_activate_policy()
preload radix tree and preallocate blkg with %GFP_KERNEL before trying
to create the root blkg.

v2: __blkg_lookup_create() was returning %NULL on blkg alloc failure
   instead of ERR_PTR() value.  Fixed.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 13589864

block/blk-cgroup.c

+43 −16
Original line number Diff line number Diff line
@@ -91,16 +91,18 @@ static void blkg_free(struct blkcg_gq *blkg) 
 * blkg_alloc - allocate a blkg

 * @blkcg: block cgroup the new blkg is associated with

 * @q: request_queue the new blkg is associated with

 * @gfp_mask: allocation mask to use

 *

 * Allocate a new blkg assocating @blkcg and @q.

 */

static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q)

static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,

				   gfp_t gfp_mask)

{

	struct blkcg_gq *blkg;

	int i;



	/* alloc and init base part */

	blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node);

	blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);

	if (!blkg)

		return NULL;
@@ -117,7 +119,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q) 
			continue;



		/* alloc per-policy data and attach it to blkg */

		pd = kzalloc_node(pol->pd_size, GFP_ATOMIC, q->node);

		pd = kzalloc_node(pol->pd_size, gfp_mask, q->node);

		if (!pd) {

			blkg_free(blkg);

			return NULL;
@@ -175,8 +177,13 @@ struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q) 
}

EXPORT_SYMBOL_GPL(blkg_lookup);



/*

 * If @new_blkg is %NULL, this function tries to allocate a new one as

 * necessary using %GFP_ATOMIC.  @new_blkg is always consumed on return.

 */

static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,

					     struct request_queue *q)

					     struct request_queue *q,

					     struct blkcg_gq *new_blkg)

{

	struct blkcg_gq *blkg;

	int ret;
@@ -188,18 +195,24 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, 
	blkg = __blkg_lookup(blkcg, q);

	if (blkg) {

		rcu_assign_pointer(blkcg->blkg_hint, blkg);

		return blkg;

		goto out_free;

	}



	/* blkg holds a reference to blkcg */

	if (!css_tryget(&blkcg->css))

		return ERR_PTR(-EINVAL);

	if (!css_tryget(&blkcg->css)) {

		blkg = ERR_PTR(-EINVAL);

		goto out_free;

	}



	/* allocate */

	ret = -ENOMEM;

	blkg = blkg_alloc(blkcg, q);

	if (unlikely(!blkg))

		goto err_put;

	if (!new_blkg) {

		new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);

		if (unlikely(!new_blkg)) {

			blkg = ERR_PTR(-ENOMEM);

			goto out_put;

		}

	}

	blkg = new_blkg;



	/* insert */

	spin_lock(&blkcg->lock);
@@ -212,10 +225,13 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, 


	if (!ret)

		return blkg;

err_put:



	blkg = ERR_PTR(ret);

out_put:

	css_put(&blkcg->css);

	blkg_free(blkg);

	return ERR_PTR(ret);

out_free:

	blkg_free(new_blkg);

	return blkg;

}



struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
@@ -227,7 +243,7 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, 
	 */

	if (unlikely(blk_queue_bypass(q)))

		return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY);

	return __blkg_lookup_create(blkcg, q);

	return __blkg_lookup_create(blkcg, q, NULL);

}

EXPORT_SYMBOL_GPL(blkg_lookup_create);
@@ -726,19 +742,30 @@ int blkcg_activate_policy(struct request_queue *q, 
	struct blkcg_gq *blkg;

	struct blkg_policy_data *pd, *n;

	int cnt = 0, ret;

	bool preloaded;



	if (blkcg_policy_enabled(q, pol))

		return 0;



	/* preallocations for root blkg */

	blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);

	if (!blkg)

		return -ENOMEM;



	preloaded = !radix_tree_preload(GFP_KERNEL);



	blk_queue_bypass_start(q);



	/* make sure the root blkg exists and count the existing blkgs */

	spin_lock_irq(q->queue_lock);



	rcu_read_lock();

	blkg = __blkg_lookup_create(&blkcg_root, q);

	blkg = __blkg_lookup_create(&blkcg_root, q, blkg);

	rcu_read_unlock();



	if (preloaded)

		radix_tree_preload_end();



	if (IS_ERR(blkg)) {

		ret = PTR_ERR(blkg);

		goto out_unlock;

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