dm thin: dont use map_context

This patch removes endio_hook_pool from dm-thin and uses per-bio data instead.

This patch removes any use of map_info in preparation for the next patch
that removes map_info from bio-based device mapper.

Signed-off-by: Mikulas Patocka <[e-mail]>
Signed-off-by: Alasdair G Kergon <[e-mail]>

drivers/md/dm-thin.c

···
 
 	struct dm_thin_new_mapping *next_mapping;
 	mempool_t *mapping_pool;
-	mempool_t *endio_hook_pool;
 
 	process_bio_fn process_bio;
 	process_bio_fn process_discard;
···
 	bio_list_init(master);
 
 	while ((bio = bio_list_pop(&bios))) {
-		struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
 		if (h->tc == tc)
 			bio_endio(bio, DM_ENDIO_REQUEUE);
···
 	if (bio->bi_rw & REQ_DISCARD)
 		return;
 
-	h = dm_get_mapinfo(bio)->ptr;
+	h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 	h->all_io_entry = dm_deferred_entry_inc(pool->all_io_ds);
 }
 
···
 static void overwrite_endio(struct bio *bio, int err)
 {
 	unsigned long flags;
-	struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 	struct dm_thin_new_mapping *m = h->overwrite_mapping;
 	struct pool *pool = m->tc->pool;
 
···
 	 * bio immediately. Otherwise we use kcopyd to clone the data first.
 	 */
 	if (io_overwrites_block(pool, bio)) {
-		struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
 		h->overwrite_mapping = m;
 		m->bio = bio;
···
 		process_prepared_mapping(m);
 
 	else if (io_overwrites_block(pool, bio)) {
-		struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
 		h->overwrite_mapping = m;
 		m->bio = bio;
···
  */
 static void retry_on_resume(struct bio *bio)
 {
-	struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 	struct thin_c *tc = h->tc;
 	struct pool *pool = tc->pool;
 	unsigned long flags;
···
 	if (bio_data_dir(bio) == WRITE && bio->bi_size)
 		break_sharing(tc, bio, block, &key, lookup_result, cell);
 	else {
-		struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
 		h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
 		inc_all_io_entry(pool, bio);
···
 	spin_unlock_irqrestore(&pool->lock, flags);
 
 	while ((bio = bio_list_pop(&bios))) {
-		struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
+		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 		struct thin_c *tc = h->tc;
 
 		/*
···
 	wake_worker(pool);
 }
 
-static struct dm_thin_endio_hook *thin_hook_bio(struct thin_c *tc, struct bio *bio)
+static void thin_hook_bio(struct thin_c *tc, struct bio *bio)
 {
-	struct pool *pool = tc->pool;
-	struct dm_thin_endio_hook *h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO);
+	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
 	h->tc = tc;
 	h->shared_read_entry = NULL;
 	h->all_io_entry = NULL;
 	h->overwrite_mapping = NULL;
-
-	return h;
 }
 
 /*
···
 	struct dm_bio_prison_cell *cell1, *cell2;
 	struct dm_cell_key key;
 
-	map_context->ptr = thin_hook_bio(tc, bio);
+	thin_hook_bio(tc, bio);
 
 	if (get_pool_mode(tc->pool) == PM_FAIL) {
 		bio_io_error(bio);
···
 	if (pool->next_mapping)
 		mempool_free(pool->next_mapping, pool->mapping_pool);
 	mempool_destroy(pool->mapping_pool);
-	mempool_destroy(pool->endio_hook_pool);
 	dm_deferred_set_destroy(pool->shared_read_ds);
 	dm_deferred_set_destroy(pool->all_io_ds);
 	kfree(pool);
 }
 
 static struct kmem_cache *_new_mapping_cache;
-static struct kmem_cache *_endio_hook_cache;
 
 static struct pool *pool_create(struct mapped_device *pool_md,
 				struct block_device *metadata_dev,
···
 		goto bad_mapping_pool;
 	}
 
-	pool->endio_hook_pool = mempool_create_slab_pool(ENDIO_HOOK_POOL_SIZE,
-							 _endio_hook_cache);
-	if (!pool->endio_hook_pool) {
-		*error = "Error creating pool's endio_hook mempool";
-		err_p = ERR_PTR(-ENOMEM);
-		goto bad_endio_hook_pool;
-	}
 	pool->ref_count = 1;
 	pool->last_commit_jiffies = jiffies;
 	pool->pool_md = pool_md;
···
 
 	return pool;
 
-bad_endio_hook_pool:
-	mempool_destroy(pool->mapping_pool);
 bad_mapping_pool:
 	dm_deferred_set_destroy(pool->all_io_ds);
 bad_all_io_ds:
···
 
 	ti->num_flush_requests = 1;
 	ti->flush_supported = true;
+	ti->per_bio_data_size = sizeof(struct dm_thin_endio_hook);
 
 	/* In case the pool supports discards, pass them on. */
 	if (tc->pool->pf.discard_enabled) {
···
 		      union map_info *map_context)
 {
 	unsigned long flags;
-	struct dm_thin_endio_hook *h = map_context->ptr;
+	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 	struct list_head work;
 	struct dm_thin_new_mapping *m, *tmp;
 	struct pool *pool = h->tc->pool;
···
 			wake_worker(pool);
 		}
 	}
-
-	mempool_free(h, pool->endio_hook_pool);
 
 	return 0;
 }
···
 	if (!_new_mapping_cache)
 		goto bad_new_mapping_cache;
 
-	_endio_hook_cache = KMEM_CACHE(dm_thin_endio_hook, 0);
-	if (!_endio_hook_cache)
-		goto bad_endio_hook_cache;
-
 	return 0;
 
-bad_endio_hook_cache:
-	kmem_cache_destroy(_new_mapping_cache);
 bad_new_mapping_cache:
 	dm_unregister_target(&pool_target);
 bad_pool_target:
···
 	dm_unregister_target(&pool_target);
 
 	kmem_cache_destroy(_new_mapping_cache);
-	kmem_cache_destroy(_endio_hook_cache);
 }
 
 module_init(dm_thin_init);