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Commit 9958f1d9 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm cache: remove all obsolete writethrough-specific code 



Now that the writethrough code is much simpler there is no need to track
so much state or cascade bio submission (as was done, via
writethrough_endio(), to issue origin then cache IO in series).

As such the obsolete writethrough list and workqueue is also removed.

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 2df3bae9

drivers/md/dm-cache-target.c

+1 −81
Original line number Diff line number Diff line
@@ -410,7 +410,6 @@ struct cache { 
	spinlock_t lock;

	struct list_head deferred_cells;

	struct bio_list deferred_bios;

	struct bio_list deferred_writethrough_bios;

	sector_t migration_threshold;

	wait_queue_head_t migration_wait;

	atomic_t nr_allocated_migrations;
@@ -446,7 +445,6 @@ struct cache { 
	struct dm_kcopyd_client *copier;

	struct workqueue_struct *wq;

	struct work_struct deferred_bio_worker;

	struct work_struct deferred_writethrough_worker;

	struct work_struct migration_worker;

	struct delayed_work waker;

	struct dm_bio_prison_v2 *prison;
@@ -491,15 +489,6 @@ struct per_bio_data { 
	struct dm_bio_prison_cell_v2 *cell;

	struct dm_hook_info hook_info;

	sector_t len;



	/*

	 * writethrough fields.  These MUST remain at the end of this

	 * structure and the 'cache' member must be the first as it

	 * is used to determine the offset of the writethrough fields.

	 */

	struct cache *cache;

	dm_cblock_t cblock;

	struct dm_bio_details bio_details;

};



struct dm_cache_migration {
@@ -538,11 +527,6 @@ static void wake_deferred_bio_worker(struct cache *cache) 
	queue_work(cache->wq, &cache->deferred_bio_worker);

}



static void wake_deferred_writethrough_worker(struct cache *cache)

{

	queue_work(cache->wq, &cache->deferred_writethrough_worker);

}



static void wake_migration_worker(struct cache *cache)

{

	if (passthrough_mode(cache))
@@ -619,15 +603,9 @@ static unsigned lock_level(struct bio *bio) 
 * Per bio data

 *--------------------------------------------------------------*/



/*

 * If using writeback, leave out struct per_bio_data's writethrough fields.

 */

#define PB_DATA_SIZE_WB (offsetof(struct per_bio_data, cache))

#define PB_DATA_SIZE_WT (sizeof(struct per_bio_data))



static size_t get_per_bio_data_size(struct cache *cache)

{

	return writethrough_mode(cache) ? PB_DATA_SIZE_WT : PB_DATA_SIZE_WB;

	return sizeof(struct per_bio_data);

}



static struct per_bio_data *get_per_bio_data(struct bio *bio, size_t data_size)
@@ -945,39 +923,6 @@ static void issue_op(struct bio *bio, void *context) 
	accounted_request(cache, bio);

}



static void defer_writethrough_bio(struct cache *cache, struct bio *bio)

{

	unsigned long flags;



	spin_lock_irqsave(&cache->lock, flags);

	bio_list_add(&cache->deferred_writethrough_bios, bio);

	spin_unlock_irqrestore(&cache->lock, flags);



	wake_deferred_writethrough_worker(cache);

}



static void writethrough_endio(struct bio *bio)

{

	struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);



	dm_unhook_bio(&pb->hook_info, bio);



	if (bio->bi_status) {

		bio_endio(bio);

		return;

	}



	dm_bio_restore(&pb->bio_details, bio);

	remap_to_cache(pb->cache, bio, pb->cblock);



	/*

	 * We can't issue this bio directly, since we're in interrupt

	 * context.  So it gets put on a bio list for processing by the

	 * worker thread.

	 */

	defer_writethrough_bio(pb->cache, bio);

}



/*

 * When running in writethrough mode we need to send writes to clean blocks

 * to both the cache and origin devices.  Clone the bio and send them in parallel.
@@ -2013,28 +1958,6 @@ static void process_deferred_bios(struct work_struct *ws) 
		schedule_commit(&cache->committer);

}



static void process_deferred_writethrough_bios(struct work_struct *ws)

{

	struct cache *cache = container_of(ws, struct cache, deferred_writethrough_worker);



	unsigned long flags;

	struct bio_list bios;

	struct bio *bio;



	bio_list_init(&bios);



	spin_lock_irqsave(&cache->lock, flags);

	bio_list_merge(&bios, &cache->deferred_writethrough_bios);

	bio_list_init(&cache->deferred_writethrough_bios);

	spin_unlock_irqrestore(&cache->lock, flags);



	/*

	 * These bios have already been through accounted_begin()

	 */

	while ((bio = bio_list_pop(&bios)))

		generic_make_request(bio);

}



/*----------------------------------------------------------------

 * Main worker loop

 *--------------------------------------------------------------*/
@@ -2679,7 +2602,6 @@ static int cache_create(struct cache_args *ca, struct cache **result) 
	spin_lock_init(&cache->lock);

	INIT_LIST_HEAD(&cache->deferred_cells);

	bio_list_init(&cache->deferred_bios);

	bio_list_init(&cache->deferred_writethrough_bios);

	atomic_set(&cache->nr_allocated_migrations, 0);

	atomic_set(&cache->nr_io_migrations, 0);

	init_waitqueue_head(&cache->migration_wait);
@@ -2718,8 +2640,6 @@ static int cache_create(struct cache_args *ca, struct cache **result) 
		goto bad;

	}

	INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);

	INIT_WORK(&cache->deferred_writethrough_worker,

		  process_deferred_writethrough_bios);

	INIT_WORK(&cache->migration_worker, check_migrations);

	INIT_DELAYED_WORK(&cache->waker, do_waker);