Commit 2c275afe authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David Sterba
Browse files

block: make blkcg_punt_bio_submit optional 



Guard all the code to punt bios to a per-cgroup submission helper by a
new CONFIG_BLK_CGROUP_PUNT_BIO symbol that is selected by btrfs.
This way non-btrfs kernel builds don't need to have this code.

Reviewed-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 12be09fe

block/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -41,6 +41,9 @@ config BLK_RQ_ALLOC_TIME 
config BLK_CGROUP_RWSTAT

	bool



config BLK_CGROUP_PUNT_BIO

	bool



config BLK_DEV_BSG_COMMON

	tristate

block/blk-cgroup.c

+42 −35
Original line number Diff line number Diff line
@@ -56,7 +56,6 @@ static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; 
static LIST_HEAD(all_blkcgs);		/* protected by blkcg_pol_mutex */



bool blkcg_debug_stats = false;

static struct workqueue_struct *blkcg_punt_bio_wq;



#define BLKG_DESTROY_BATCH_SIZE  64
@@ -166,7 +165,9 @@ static void __blkg_release(struct rcu_head *rcu) 
{

	struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);



#ifdef CONFIG_BLK_CGROUP_PUNT_BIO

	WARN_ON(!bio_list_empty(&blkg->async_bios));

#endif



	/* release the blkcg and parent blkg refs this blkg has been holding */

	css_put(&blkg->blkcg->css);
@@ -188,6 +189,9 @@ static void blkg_release(struct percpu_ref *ref) 
	call_rcu(&blkg->rcu_head, __blkg_release);

}



#ifdef CONFIG_BLK_CGROUP_PUNT_BIO

static struct workqueue_struct *blkcg_punt_bio_wq;



static void blkg_async_bio_workfn(struct work_struct *work)

{

	struct blkcg_gq *blkg = container_of(work, struct blkcg_gq,
@@ -214,6 +218,40 @@ static void blkg_async_bio_workfn(struct work_struct *work) 
		blk_finish_plug(&plug);

}



/*

 * When a shared kthread issues a bio for a cgroup, doing so synchronously can

 * lead to priority inversions as the kthread can be trapped waiting for that

 * cgroup.  Use this helper instead of submit_bio to punt the actual issuing to

 * a dedicated per-blkcg work item to avoid such priority inversions.

 */

void blkcg_punt_bio_submit(struct bio *bio)

{

	struct blkcg_gq *blkg = bio->bi_blkg;



	if (blkg->parent) {

		spin_lock(&blkg->async_bio_lock);

		bio_list_add(&blkg->async_bios, bio);

		spin_unlock(&blkg->async_bio_lock);

		queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work);

	} else {

		/* never bounce for the root cgroup */

		submit_bio(bio);

	}

}

EXPORT_SYMBOL_GPL(blkcg_punt_bio_submit);



static int __init blkcg_punt_bio_init(void)

{

	blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio",

					    WQ_MEM_RECLAIM | WQ_FREEZABLE |

					    WQ_UNBOUND | WQ_SYSFS, 0);

	if (!blkcg_punt_bio_wq)

		return -ENOMEM;

	return 0;

}

subsys_initcall(blkcg_punt_bio_init);

#endif /* CONFIG_BLK_CGROUP_PUNT_BIO */



/**

 * bio_blkcg_css - return the blkcg CSS associated with a bio

 * @bio: target bio
@@ -269,10 +307,12 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk, 


	blkg->q = disk->queue;

	INIT_LIST_HEAD(&blkg->q_node);

	blkg->blkcg = blkcg;

#ifdef CONFIG_BLK_CGROUP_PUNT_BIO

	spin_lock_init(&blkg->async_bio_lock);

	bio_list_init(&blkg->async_bios);

	INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn);

	blkg->blkcg = blkcg;

#endif



	u64_stats_init(&blkg->iostat.sync);

	for_each_possible_cpu(cpu) {
@@ -1688,28 +1728,6 @@ void blkcg_policy_unregister(struct blkcg_policy *pol) 
}

EXPORT_SYMBOL_GPL(blkcg_policy_unregister);



/*

 * When a shared kthread issues a bio for a cgroup, doing so synchronously can

 * lead to priority inversions as the kthread can be trapped waiting for that

 * cgroup.  Use this helper instead of submit_bio to punt the actual issuing to

 * a dedicated per-blkcg work item to avoid such priority inversions.

 */

void blkcg_punt_bio_submit(struct bio *bio)

{

	struct blkcg_gq *blkg = bio->bi_blkg;



	if (blkg->parent) {

		spin_lock(&blkg->async_bio_lock);

		bio_list_add(&blkg->async_bios, bio);

		spin_unlock(&blkg->async_bio_lock);

		queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work);

	} else {

		/* never bounce for the root cgroup */

		submit_bio(bio);

	}

}

EXPORT_SYMBOL_GPL(blkcg_punt_bio_submit);



/*

 * Scale the accumulated delay based on how long it has been since we updated

 * the delay.  We only call this when we are adding delay, in case it's been a
@@ -2088,16 +2106,5 @@ bool blk_cgroup_congested(void) 
	return ret;

}



static int __init blkcg_init(void)

{

	blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio",

					    WQ_MEM_RECLAIM | WQ_FREEZABLE |

					    WQ_UNBOUND | WQ_SYSFS, 0);

	if (!blkcg_punt_bio_wq)

		return -ENOMEM;

	return 0;

}

subsys_initcall(blkcg_init);



module_param(blkcg_debug_stats, bool, 0644);

MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not");

block/blk-cgroup.h

+2 −1
Original line number Diff line number Diff line
@@ -72,9 +72,10 @@ struct blkcg_gq { 
	struct blkg_iostat_set		iostat;



	struct blkg_policy_data		*pd[BLKCG_MAX_POLS];



#ifdef CONFIG_BLK_CGROUP_PUNT_BIO

	spinlock_t			async_bio_lock;

	struct bio_list			async_bios;

#endif

	union {

		struct work_struct	async_bio_work;

		struct work_struct	free_work;

fs/btrfs/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 


config BTRFS_FS

	tristate "Btrfs filesystem support"

	select BLK_CGROUP_PUNT_BIO

	select CRYPTO

	select CRYPTO_CRC32C

	select LIBCRC32C