Commit 49b1212d authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Use blkdev_issue_discard() 



The old asynchronous discard code was really a relic from when all the
allocation code was asynchronous - now that allocation runs out of a
dedicated thread there's no point in keeping around all that complicated
machinery.

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent dd9ec84d

drivers/md/bcache/alloc.c

+11 −103
Original line number Diff line number Diff line
@@ -63,13 +63,12 @@ 
#include "bcache.h"

#include "btree.h"



#include <linux/blkdev.h>

#include <linux/freezer.h>

#include <linux/kthread.h>

#include <linux/random.h>

#include <trace/events/bcache.h>



#define MAX_IN_FLIGHT_DISCARDS		8U



/* Bucket heap / gen */



uint8_t bch_inc_gen(struct cache *ca, struct bucket *b)
@@ -121,75 +120,6 @@ void bch_rescale_priorities(struct cache_set *c, int sectors) 
	mutex_unlock(&c->bucket_lock);

}



/* Discard/TRIM */



struct discard {

	struct list_head	list;

	struct work_struct	work;

	struct cache		*ca;

	long			bucket;



	struct bio		bio;

	struct bio_vec		bv;

};



static void discard_finish(struct work_struct *w)

{

	struct discard *d = container_of(w, struct discard, work);

	struct cache *ca = d->ca;

	char buf[BDEVNAME_SIZE];



	if (!test_bit(BIO_UPTODATE, &d->bio.bi_flags)) {

		pr_notice("discard error on %s, disabling",

			 bdevname(ca->bdev, buf));

		d->ca->discard = 0;

	}



	mutex_lock(&ca->set->bucket_lock);



	fifo_push(&ca->free, d->bucket);

	list_add(&d->list, &ca->discards);

	atomic_dec(&ca->discards_in_flight);



	mutex_unlock(&ca->set->bucket_lock);



	closure_wake_up(&ca->set->bucket_wait);

	wake_up_process(ca->alloc_thread);



	closure_put(&ca->set->cl);

}



static void discard_endio(struct bio *bio, int error)

{

	struct discard *d = container_of(bio, struct discard, bio);

	schedule_work(&d->work);

}



static void do_discard(struct cache *ca, long bucket)

{

	struct discard *d = list_first_entry(&ca->discards,

					     struct discard, list);



	list_del(&d->list);

	d->bucket = bucket;



	atomic_inc(&ca->discards_in_flight);

	closure_get(&ca->set->cl);



	bio_init(&d->bio);



	d->bio.bi_sector	= bucket_to_sector(ca->set, d->bucket);

	d->bio.bi_bdev		= ca->bdev;

	d->bio.bi_rw		= REQ_WRITE|REQ_DISCARD;

	d->bio.bi_max_vecs	= 1;

	d->bio.bi_io_vec	= d->bio.bi_inline_vecs;

	d->bio.bi_size		= bucket_bytes(ca);

	d->bio.bi_end_io	= discard_endio;

	bio_set_prio(&d->bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));



	submit_bio(0, &d->bio);

}



/* Allocation */



static inline bool can_inc_bucket_gen(struct bucket *b)
@@ -398,17 +328,19 @@ static int bch_allocator_thread(void *arg) 
			else

				break;



			allocator_wait(ca, (int) fifo_free(&ca->free) >

				       atomic_read(&ca->discards_in_flight));



			if (ca->discard) {

				allocator_wait(ca, !list_empty(&ca->discards));

				do_discard(ca, bucket);

			} else {

				mutex_unlock(&ca->set->bucket_lock);

				blkdev_issue_discard(ca->bdev,

					bucket_to_sector(ca->set, bucket),

					ca->sb.block_size, GFP_KERNEL, 0);

				mutex_lock(&ca->set->bucket_lock);

			}



			allocator_wait(ca, !fifo_full(&ca->free));



			fifo_push(&ca->free, bucket);

			closure_wake_up(&ca->set->bucket_wait);

		}

		}



		/*

		 * We've run out of free buckets, we need to find some buckets
@@ -556,22 +488,8 @@ int bch_cache_allocator_start(struct cache *ca) 
	return 0;

}



void bch_cache_allocator_exit(struct cache *ca)

{

	struct discard *d;



	while (!list_empty(&ca->discards)) {

		d = list_first_entry(&ca->discards, struct discard, list);

		cancel_work_sync(&d->work);

		list_del(&d->list);

		kfree(d);

	}

}



int bch_cache_allocator_init(struct cache *ca)

{

	unsigned i;



	/*

	 * Reserve:

	 * Prio/gen writes first
@@ -589,15 +507,5 @@ int bch_cache_allocator_init(struct cache *ca) 
	ca->watermark[WATERMARK_NONE] = ca->free.size / 2 +

		ca->watermark[WATERMARK_MOVINGGC];



	for (i = 0; i < MAX_IN_FLIGHT_DISCARDS; i++) {

		struct discard *d = kzalloc(sizeof(*d), GFP_KERNEL);

		if (!d)

			return -ENOMEM;



		d->ca = ca;

		INIT_WORK(&d->work, discard_finish);

		list_add(&d->list, &ca->discards);

	}



	return 0;

}

drivers/md/bcache/bcache.h

+0 −10
Original line number Diff line number Diff line
@@ -620,15 +620,6 @@ struct cache { 


	bool			discard; /* Get rid of? */



	/*

	 * We preallocate structs for issuing discards to buckets, and keep them

	 * on this list when they're not in use; do_discard() issues discards

	 * whenever there's work to do and is called by free_some_buckets() and

	 * when a discard finishes.

	 */

	atomic_t		discards_in_flight;

	struct list_head	discards;



	struct journal_device	journal;



	/* The rest of this all shows up in sysfs */
@@ -1222,7 +1213,6 @@ int bch_btree_cache_alloc(struct cache_set *); 
void bch_moving_init_cache_set(struct cache_set *);



int bch_cache_allocator_start(struct cache *ca);

void bch_cache_allocator_exit(struct cache *ca);

int bch_cache_allocator_init(struct cache *ca);



void bch_debug_exit(void);

drivers/md/bcache/super.c

+0 −4
Original line number Diff line number Diff line
@@ -1725,8 +1725,6 @@ void bch_cache_release(struct kobject *kobj) 
	if (ca->set)

		ca->set->cache[ca->sb.nr_this_dev] = NULL;



	bch_cache_allocator_exit(ca);



	bio_split_pool_free(&ca->bio_split_hook);



	free_pages((unsigned long) ca->disk_buckets, ilog2(bucket_pages(ca)));
@@ -1758,8 +1756,6 @@ static int cache_alloc(struct cache_sb *sb, struct cache *ca) 
	__module_get(THIS_MODULE);

	kobject_init(&ca->kobj, &bch_cache_ktype);



	INIT_LIST_HEAD(&ca->discards);



	bio_init(&ca->journal.bio);

	ca->journal.bio.bi_max_vecs = 8;

	ca->journal.bio.bi_io_vec = ca->journal.bio.bi_inline_vecs;

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