struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
unsigned int reserved_tags, int node)
{
unsigned int nr_tags, nr_cache;
struct blk_mq_tags *tags;
int ret;
if (total_tags > BLK_MQ_TAG_MAX) {
pr_err("blk-mq: tag depth too large\n");
return NULL;
}
tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node);
if (!tags)
return NULL;
nr_tags = total_tags - reserved_tags;
nr_cache = nr_tags / num_possible_cpus();
if (nr_cache < BLK_MQ_TAG_CACHE_MIN)
nr_cache = BLK_MQ_TAG_CACHE_MIN;
else if (nr_cache > BLK_MQ_TAG_CACHE_MAX)
nr_cache = BLK_MQ_TAG_CACHE_MAX;
tags->nr_tags = total_tags;
tags->nr_reserved_tags = reserved_tags;
tags->nr_max_cache = nr_cache;
tags->nr_batch_move = max(1u, nr_cache / 2);
ret = __percpu_ida_init(&tags->free_tags, tags->nr_tags -
tags->nr_reserved_tags,
tags->nr_max_cache,
tags->nr_batch_move);
if (ret)
goto err_free_tags;
if (reserved_tags) {
/*
* With max_cahe and batch set to 1, the allocator fallbacks to
* no cached. It's fine reserved tags allocation is slow.
*/
ret = __percpu_ida_init(&tags->reserved_tags, reserved_tags,
1, 1);
if (ret)
goto err_reserved_tags;
}
return tags;
err_reserved_tags:
percpu_ida_destroy(&tags->free_tags);
err_free_tags:
kfree(tags);
return NULL;
}
/**
* percpu_ida_init - initialize a percpu tag pool
* @pool: pool to initialize
* @nr_tags: number of tags that will be available for allocation
*
* Initializes @pool so that it can be used to allocate tags - integers in the
* range [0, nr_tags). Typically, they'll be used by driver code to refer to a
* preallocated array of tag structures.
*
* Allocation is percpu, but sharding is limited by nr_tags - for best
* performance, the workload should not span more cpus than nr_tags / 128.
*/
int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
unsigned long max_size, unsigned long batch_size)
{
unsigned i, cpu, order;
memset(pool, 0, sizeof(*pool));
init_waitqueue_head(&pool->wait);
spin_lock_init(&pool->lock);
pool->nr_tags = nr_tags;
pool->percpu_max_size = max_size;
pool->percpu_batch_size = batch_size;
/* Guard against overflow */
if (nr_tags > (unsigned) INT_MAX + 1) {
pr_err("percpu_ida_init(): nr_tags too large\n");
return -EINVAL;
}
order = get_order(nr_tags * sizeof(unsigned));
pool->freelist = (void *) __get_free_pages(GFP_KERNEL, order);
if (!pool->freelist)
return -ENOMEM;
for (i = 0; i < nr_tags; i++)
pool->freelist[i] = i;
pool->nr_free = nr_tags;
pool->tag_cpu = __alloc_percpu(sizeof(struct percpu_ida_cpu) +
pool->percpu_max_size * sizeof(unsigned),
sizeof(unsigned));
if (!pool->tag_cpu)
goto err;
for_each_possible_cpu(cpu)
spin_lock_init(&per_cpu_ptr(pool->tag_cpu, cpu)->lock);
return 0;
err:
percpu_ida_destroy(pool);
return -ENOMEM;
}
void blk_mq_free_tags(struct blk_mq_tags *tags)
{
percpu_ida_destroy(&tags->free_tags);
percpu_ida_destroy(&tags->reserved_tags);
kfree(tags);
}
