static int cache_create()

in dm-cache-target.c [2352:2546]

• 161 lines of code
• 19 McCabe index (conditional complexity)

static int cache_create(struct cache_args *ca, struct cache **result)
{
	int r = 0;
	char **error = &ca->ti->error;
	struct cache *cache;
	struct dm_target *ti = ca->ti;
	dm_block_t origin_blocks;
	struct dm_cache_metadata *cmd;
	bool may_format = ca->features.mode == CM_WRITE;

	cache = kzalloc(sizeof(*cache), GFP_KERNEL);
	if (!cache)
		return -ENOMEM;

	cache->ti = ca->ti;
	ti->private = cache;
	ti->num_flush_bios = 2;
	ti->flush_supported = true;

	ti->num_discard_bios = 1;
	ti->discards_supported = true;

	ti->per_io_data_size = sizeof(struct per_bio_data);

	cache->features = ca->features;
	if (writethrough_mode(cache)) {
		/* Create bioset for writethrough bios issued to origin */
		r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
		if (r)
			goto bad;
	}

	cache->metadata_dev = ca->metadata_dev;
	cache->origin_dev = ca->origin_dev;
	cache->cache_dev = ca->cache_dev;

	ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;

	origin_blocks = cache->origin_sectors = ca->origin_sectors;
	origin_blocks = block_div(origin_blocks, ca->block_size);
	cache->origin_blocks = to_oblock(origin_blocks);

	cache->sectors_per_block = ca->block_size;
	if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
		r = -EINVAL;
		goto bad;
	}

	if (ca->block_size & (ca->block_size - 1)) {
		dm_block_t cache_size = ca->cache_sectors;

		cache->sectors_per_block_shift = -1;
		cache_size = block_div(cache_size, ca->block_size);
		set_cache_size(cache, to_cblock(cache_size));
	} else {
		cache->sectors_per_block_shift = __ffs(ca->block_size);
		set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
	}

	r = create_cache_policy(cache, ca, error);
	if (r)
		goto bad;

	cache->policy_nr_args = ca->policy_argc;
	cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;

	r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
	if (r) {
		*error = "Error setting cache policy's config values";
		goto bad;
	}

	cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
				     ca->block_size, may_format,
				     dm_cache_policy_get_hint_size(cache->policy),
				     ca->features.metadata_version);
	if (IS_ERR(cmd)) {
		*error = "Error creating metadata object";
		r = PTR_ERR(cmd);
		goto bad;
	}
	cache->cmd = cmd;
	set_cache_mode(cache, CM_WRITE);
	if (get_cache_mode(cache) != CM_WRITE) {
		*error = "Unable to get write access to metadata, please check/repair metadata.";
		r = -EINVAL;
		goto bad;
	}

	if (passthrough_mode(cache)) {
		bool all_clean;

		r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
		if (r) {
			*error = "dm_cache_metadata_all_clean() failed";
			goto bad;
		}

		if (!all_clean) {
			*error = "Cannot enter passthrough mode unless all blocks are clean";
			r = -EINVAL;
			goto bad;
		}

		policy_allow_migrations(cache->policy, false);
	}

	spin_lock_init(&cache->lock);
	bio_list_init(&cache->deferred_bios);
	atomic_set(&cache->nr_allocated_migrations, 0);
	atomic_set(&cache->nr_io_migrations, 0);
	init_waitqueue_head(&cache->migration_wait);

	r = -ENOMEM;
	atomic_set(&cache->nr_dirty, 0);
	cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
	if (!cache->dirty_bitset) {
		*error = "could not allocate dirty bitset";
		goto bad;
	}
	clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));

	cache->discard_block_size =
		calculate_discard_block_size(cache->sectors_per_block,
					     cache->origin_sectors);
	cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
							      cache->discard_block_size));
	cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
	if (!cache->discard_bitset) {
		*error = "could not allocate discard bitset";
		goto bad;
	}
	clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));

	cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
	if (IS_ERR(cache->copier)) {
		*error = "could not create kcopyd client";
		r = PTR_ERR(cache->copier);
		goto bad;
	}

	cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
	if (!cache->wq) {
		*error = "could not create workqueue for metadata object";
		goto bad;
	}
	INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
	INIT_WORK(&cache->migration_worker, check_migrations);
	INIT_DELAYED_WORK(&cache->waker, do_waker);

	cache->prison = dm_bio_prison_create_v2(cache->wq);
	if (!cache->prison) {
		*error = "could not create bio prison";
		goto bad;
	}

	r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
				   migration_cache);
	if (r) {
		*error = "Error creating cache's migration mempool";
		goto bad;
	}

	cache->need_tick_bio = true;
	cache->sized = false;
	cache->invalidate = false;
	cache->commit_requested = false;
	cache->loaded_mappings = false;
	cache->loaded_discards = false;

	load_stats(cache);

	atomic_set(&cache->stats.demotion, 0);
	atomic_set(&cache->stats.promotion, 0);
	atomic_set(&cache->stats.copies_avoided, 0);
	atomic_set(&cache->stats.cache_cell_clash, 0);
	atomic_set(&cache->stats.commit_count, 0);
	atomic_set(&cache->stats.discard_count, 0);

	spin_lock_init(&cache->invalidation_lock);
	INIT_LIST_HEAD(&cache->invalidation_requests);

	batcher_init(&cache->committer, commit_op, cache,
		     issue_op, cache, cache->wq);
	dm_iot_init(&cache->tracker);

	init_rwsem(&cache->background_work_lock);
	prevent_background_work(cache);

	*result = cache;
	return 0;
bad:
	destroy(cache);
	return r;
}