dm cache: remove all obsolete writethrough-specific code

commit 9958f1d9a04efb3db19134482b3f4c6897e0e7b8 upstream.

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: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 81 deletions

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 2b107b579c2a..280873b13e74 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -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
  *--------------------------------------------------------------*/
@@ -2690,7 +2613,6 @@ 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);
@@ -2729,8 +2651,6 @@ 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);