]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blobdiff - block/blk-mq.c
blk-mq: add blk_mq_start_hw_queues
[mirror_ubuntu-artful-kernel.git] / block / blk-mq.c
index 48d2d8495f5e5d3b0e91f391556aa752ce86d94f..543bbc08a2614e8ee6f6eecb42fa096b9f0fe746 100644 (file)
@@ -81,7 +81,8 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
 
        tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
        if (tag != BLK_MQ_TAG_FAIL) {
-               rq = hctx->rqs[tag];
+               rq = hctx->tags->rqs[tag];
+               blk_rq_init(hctx->queue, rq);
                rq->tag = tag;
 
                return rq;
@@ -257,9 +258,7 @@ static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
        const int tag = rq->tag;
        struct request_queue *q = rq->q;
 
-       blk_rq_init(hctx->queue, rq);
        blk_mq_put_tag(hctx->tags, tag);
-
        blk_mq_queue_exit(q);
 }
 
@@ -295,20 +294,27 @@ void blk_mq_clone_flush_request(struct request *flush_rq,
                hctx->cmd_size);
 }
 
-bool blk_mq_end_io_partial(struct request *rq, int error, unsigned int nr_bytes)
+inline void __blk_mq_end_io(struct request *rq, int error)
 {
-       if (blk_update_request(rq, error, blk_rq_bytes(rq)))
-               return true;
-
        blk_account_io_done(rq);
 
-       if (rq->end_io)
+       if (rq->end_io) {
                rq->end_io(rq, error);
-       else
+       } else {
+               if (unlikely(blk_bidi_rq(rq)))
+                       blk_mq_free_request(rq->next_rq);
                blk_mq_free_request(rq);
-       return false;
+       }
+}
+EXPORT_SYMBOL(__blk_mq_end_io);
+
+void blk_mq_end_io(struct request *rq, int error)
+{
+       if (blk_update_request(rq, error, blk_rq_bytes(rq)))
+               BUG();
+       __blk_mq_end_io(rq, error);
 }
-EXPORT_SYMBOL(blk_mq_end_io_partial);
+EXPORT_SYMBOL(blk_mq_end_io);
 
 static void __blk_mq_complete_request_remote(void *data)
 {
@@ -363,6 +369,8 @@ static void blk_mq_start_request(struct request *rq, bool last)
        trace_block_rq_issue(q, rq);
 
        rq->resid_len = blk_rq_bytes(rq);
+       if (unlikely(blk_bidi_rq(rq)))
+               rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
 
        /*
         * Just mark start time and set the started bit. Due to memory
@@ -405,6 +413,12 @@ static void blk_mq_requeue_request(struct request *rq)
                rq->nr_phys_segments--;
 }
 
+struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
+{
+       return tags->rqs[tag];
+}
+EXPORT_SYMBOL(blk_mq_tag_to_rq);
+
 struct blk_mq_timeout_data {
        struct blk_mq_hw_ctx *hctx;
        unsigned long *next;
@@ -426,12 +440,13 @@ static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
        do {
                struct request *rq;
 
-               tag = find_next_zero_bit(free_tags, hctx->queue_depth, tag);
-               if (tag >= hctx->queue_depth)
+               tag = find_next_zero_bit(free_tags, hctx->tags->nr_tags, tag);
+               if (tag >= hctx->tags->nr_tags)
                        break;
 
-               rq = hctx->rqs[tag++];
-
+               rq = blk_mq_tag_to_rq(hctx->tags, tag++);
+               if (rq->q != hctx->queue)
+                       continue;
                if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
                        continue;
 
@@ -528,7 +543,7 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
        LIST_HEAD(rq_list);
        int bit, queued;
 
-       WARN_ON(!preempt_count());
+       WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask));
 
        if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
                return;
@@ -625,7 +640,7 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
        if (!async && cpumask_test_cpu(smp_processor_id(), hctx->cpumask))
                __blk_mq_run_hw_queue(hctx);
        else if (hctx->queue->nr_hw_queues == 1)
-               kblockd_schedule_delayed_work(&hctx->delayed_work, 0);
+               kblockd_schedule_delayed_work(&hctx->run_work, 0);
        else {
                unsigned int cpu;
 
@@ -636,7 +651,7 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
                 * just queue on the first CPU.
                 */
                cpu = cpumask_first(hctx->cpumask);
-               kblockd_schedule_delayed_work_on(cpu, &hctx->delayed_work, 0);
+               kblockd_schedule_delayed_work_on(cpu, &hctx->run_work, 0);
        }
 }
 
@@ -660,7 +675,8 @@ EXPORT_SYMBOL(blk_mq_run_queues);
 
 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
-       cancel_delayed_work(&hctx->delayed_work);
+       cancel_delayed_work(&hctx->run_work);
+       cancel_delayed_work(&hctx->delay_work);
        set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 }
 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
@@ -685,7 +701,18 @@ void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
 }
 EXPORT_SYMBOL(blk_mq_start_hw_queue);
 
-void blk_mq_start_stopped_hw_queues(struct request_queue *q)
+void blk_mq_start_hw_queues(struct request_queue *q)
+{
+       struct blk_mq_hw_ctx *hctx;
+       int i;
+
+       queue_for_each_hw_ctx(q, hctx, i)
+               blk_mq_start_hw_queue(hctx);
+}
+EXPORT_SYMBOL(blk_mq_start_hw_queues);
+
+
+void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
 {
        struct blk_mq_hw_ctx *hctx;
        int i;
@@ -696,23 +723,52 @@ void blk_mq_start_stopped_hw_queues(struct request_queue *q)
 
                clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
                preempt_disable();
-               blk_mq_run_hw_queue(hctx, true);
+               blk_mq_run_hw_queue(hctx, async);
                preempt_enable();
        }
 }
 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
 
-static void blk_mq_work_fn(struct work_struct *work)
+static void blk_mq_run_work_fn(struct work_struct *work)
 {
        struct blk_mq_hw_ctx *hctx;
 
-       hctx = container_of(work, struct blk_mq_hw_ctx, delayed_work.work);
+       hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
 
-       preempt_disable();
        __blk_mq_run_hw_queue(hctx);
-       preempt_enable();
 }
 
+static void blk_mq_delay_work_fn(struct work_struct *work)
+{
+       struct blk_mq_hw_ctx *hctx;
+
+       hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
+
+       if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
+               __blk_mq_run_hw_queue(hctx);
+}
+
+void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
+{
+       unsigned long tmo = msecs_to_jiffies(msecs);
+
+       if (hctx->queue->nr_hw_queues == 1)
+               kblockd_schedule_delayed_work(&hctx->delay_work, tmo);
+       else {
+               unsigned int cpu;
+
+               /*
+                * It'd be great if the workqueue API had a way to pass
+                * in a mask and had some smarts for more clever placement
+                * than the first CPU. Or we could round-robin here. For now,
+                * just queue on the first CPU.
+                */
+               cpu = cpumask_first(hctx->cpumask);
+               kblockd_schedule_delayed_work_on(cpu, &hctx->delay_work, tmo);
+       }
+}
+EXPORT_SYMBOL(blk_mq_delay_queue);
+
 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
                                    struct request *rq, bool at_head)
 {
@@ -970,11 +1026,11 @@ struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
 }
 EXPORT_SYMBOL(blk_mq_map_queue);
 
-struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *reg,
+struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_tag_set *set,
                                                   unsigned int hctx_index)
 {
        return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
-                               GFP_KERNEL | __GFP_ZERO, reg->numa_node);
+                               GFP_KERNEL | __GFP_ZERO, set->numa_node);
 }
 EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
 
@@ -1031,31 +1087,31 @@ static void blk_mq_hctx_notify(void *data, unsigned long action,
        blk_mq_put_ctx(ctx);
 }
 
-static void blk_mq_free_rq_map(struct blk_mq_hw_ctx *hctx, void *driver_data)
+static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
+               struct blk_mq_tags *tags, unsigned int hctx_idx)
 {
        struct page *page;
 
-       if (hctx->rqs && hctx->queue->mq_ops->exit_request) {
+       if (tags->rqs && set->ops->exit_request) {
                int i;
 
-               for (i = 0; i < hctx->queue_depth; i++) {
-                       if (!hctx->rqs[i])
+               for (i = 0; i < tags->nr_tags; i++) {
+                       if (!tags->rqs[i])
                                continue;
-                       hctx->queue->mq_ops->exit_request(driver_data, hctx,
-                                                         hctx->rqs[i], i);
+                       set->ops->exit_request(set->driver_data, tags->rqs[i],
+                                               hctx_idx, i);
                }
        }
 
-       while (!list_empty(&hctx->page_list)) {
-               page = list_first_entry(&hctx->page_list, struct page, lru);
+       while (!list_empty(&tags->page_list)) {
+               page = list_first_entry(&tags->page_list, struct page, lru);
                list_del_init(&page->lru);
                __free_pages(page, page->private);
        }
 
-       kfree(hctx->rqs);
+       kfree(tags->rqs);
 
-       if (hctx->tags)
-               blk_mq_free_tags(hctx->tags);
+       blk_mq_free_tags(tags);
 }
 
 static size_t order_to_size(unsigned int order)
@@ -1068,30 +1124,36 @@ static size_t order_to_size(unsigned int order)
        return ret;
 }
 
-static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
-               struct blk_mq_reg *reg, void *driver_data, int node)
+static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
+               unsigned int hctx_idx)
 {
-       unsigned int reserved_tags = reg->reserved_tags;
+       struct blk_mq_tags *tags;
        unsigned int i, j, entries_per_page, max_order = 4;
        size_t rq_size, left;
-       int error;
 
-       INIT_LIST_HEAD(&hctx->page_list);
+       tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
+                               set->numa_node);
+       if (!tags)
+               return NULL;
+
+       INIT_LIST_HEAD(&tags->page_list);
 
-       hctx->rqs = kmalloc_node(hctx->queue_depth * sizeof(struct request *),
-                                       GFP_KERNEL, node);
-       if (!hctx->rqs)
-               return -ENOMEM;
+       tags->rqs = kmalloc_node(set->queue_depth * sizeof(struct request *),
+                                       GFP_KERNEL, set->numa_node);
+       if (!tags->rqs) {
+               blk_mq_free_tags(tags);
+               return NULL;
+       }
 
        /*
         * rq_size is the size of the request plus driver payload, rounded
         * to the cacheline size
         */
-       rq_size = round_up(sizeof(struct request) + hctx->cmd_size,
+       rq_size = round_up(sizeof(struct request) + set->cmd_size,
                                cache_line_size());
-       left = rq_size * hctx->queue_depth;
+       left = rq_size * set->queue_depth;
 
-       for (i = 0; i < hctx->queue_depth;) {
+       for (i = 0; i < set->queue_depth; ) {
                int this_order = max_order;
                struct page *page;
                int to_do;
@@ -1101,7 +1163,8 @@ static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
                        this_order--;
 
                do {
-                       page = alloc_pages_node(node, GFP_KERNEL, this_order);
+                       page = alloc_pages_node(set->numa_node, GFP_KERNEL,
+                                               this_order);
                        if (page)
                                break;
                        if (!this_order--)
@@ -1111,23 +1174,22 @@ static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
                } while (1);
 
                if (!page)
-                       break;
+                       goto fail;
 
                page->private = this_order;
-               list_add_tail(&page->lru, &hctx->page_list);
+               list_add_tail(&page->lru, &tags->page_list);
 
                p = page_address(page);
                entries_per_page = order_to_size(this_order) / rq_size;
-               to_do = min(entries_per_page, hctx->queue_depth - i);
+               to_do = min(entries_per_page, set->queue_depth - i);
                left -= to_do * rq_size;
                for (j = 0; j < to_do; j++) {
-                       hctx->rqs[i] = p;
-                       blk_rq_init(hctx->queue, hctx->rqs[i]);
-                       if (reg->ops->init_request) {
-                               error = reg->ops->init_request(driver_data,
-                                               hctx, hctx->rqs[i], i);
-                               if (error)
-                                       goto err_rq_map;
+                       tags->rqs[i] = p;
+                       if (set->ops->init_request) {
+                               if (set->ops->init_request(set->driver_data,
+                                               tags->rqs[i], hctx_idx, i,
+                                               set->numa_node))
+                                       goto fail;
                        }
 
                        p += rq_size;
@@ -1135,30 +1197,16 @@ static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
                }
        }
 
-       if (i < (reserved_tags + BLK_MQ_TAG_MIN)) {
-               error = -ENOMEM;
-               goto err_rq_map;
-       }
-       if (i != hctx->queue_depth) {
-               hctx->queue_depth = i;
-               pr_warn("%s: queue depth set to %u because of low memory\n",
-                                       __func__, i);
-       }
-
-       hctx->tags = blk_mq_init_tags(hctx->queue_depth, reserved_tags, node);
-       if (!hctx->tags) {
-               error = -ENOMEM;
-               goto err_rq_map;
-       }
+       return tags;
 
-       return 0;
-err_rq_map:
-       blk_mq_free_rq_map(hctx, driver_data);
-       return error;
+fail:
+       pr_warn("%s: failed to allocate requests\n", __func__);
+       blk_mq_free_rq_map(set, tags, hctx_idx);
+       return NULL;
 }
 
 static int blk_mq_init_hw_queues(struct request_queue *q,
-                                struct blk_mq_reg *reg, void *driver_data)
+               struct blk_mq_tag_set *set)
 {
        struct blk_mq_hw_ctx *hctx;
        unsigned int i, j;
@@ -1172,23 +1220,22 @@ static int blk_mq_init_hw_queues(struct request_queue *q,
 
                node = hctx->numa_node;
                if (node == NUMA_NO_NODE)
-                       node = hctx->numa_node = reg->numa_node;
+                       node = hctx->numa_node = set->numa_node;
 
-               INIT_DELAYED_WORK(&hctx->delayed_work, blk_mq_work_fn);
+               INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
+               INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
                spin_lock_init(&hctx->lock);
                INIT_LIST_HEAD(&hctx->dispatch);
                hctx->queue = q;
                hctx->queue_num = i;
-               hctx->flags = reg->flags;
-               hctx->queue_depth = reg->queue_depth;
-               hctx->cmd_size = reg->cmd_size;
+               hctx->flags = set->flags;
+               hctx->cmd_size = set->cmd_size;
 
                blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
                                                blk_mq_hctx_notify, hctx);
                blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
 
-               if (blk_mq_init_rq_map(hctx, reg, driver_data, node))
-                       break;
+               hctx->tags = set->tags[i];
 
                /*
                 * Allocate space for all possible cpus to avoid allocation in
@@ -1208,8 +1255,8 @@ static int blk_mq_init_hw_queues(struct request_queue *q,
                hctx->nr_ctx_map = num_maps;
                hctx->nr_ctx = 0;
 
-               if (reg->ops->init_hctx &&
-                   reg->ops->init_hctx(hctx, driver_data, i))
+               if (set->ops->init_hctx &&
+                   set->ops->init_hctx(hctx, set->driver_data, i))
                        break;
        }
 
@@ -1223,11 +1270,10 @@ static int blk_mq_init_hw_queues(struct request_queue *q,
                if (i == j)
                        break;
 
-               if (reg->ops->exit_hctx)
-                       reg->ops->exit_hctx(hctx, j);
+               if (set->ops->exit_hctx)
+                       set->ops->exit_hctx(hctx, j);
 
                blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
-               blk_mq_free_rq_map(hctx, driver_data);
                kfree(hctx->ctxs);
        }
 
@@ -1292,41 +1338,25 @@ static void blk_mq_map_swqueue(struct request_queue *q)
        }
 }
 
-struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
-                                       void *driver_data)
+struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 {
        struct blk_mq_hw_ctx **hctxs;
        struct blk_mq_ctx *ctx;
        struct request_queue *q;
        int i;
 
-       if (!reg->nr_hw_queues ||
-           !reg->ops->queue_rq || !reg->ops->map_queue ||
-           !reg->ops->alloc_hctx || !reg->ops->free_hctx)
-               return ERR_PTR(-EINVAL);
-
-       if (!reg->queue_depth)
-               reg->queue_depth = BLK_MQ_MAX_DEPTH;
-       else if (reg->queue_depth > BLK_MQ_MAX_DEPTH) {
-               pr_err("blk-mq: queuedepth too large (%u)\n", reg->queue_depth);
-               reg->queue_depth = BLK_MQ_MAX_DEPTH;
-       }
-
-       if (reg->queue_depth < (reg->reserved_tags + BLK_MQ_TAG_MIN))
-               return ERR_PTR(-EINVAL);
-
        ctx = alloc_percpu(struct blk_mq_ctx);
        if (!ctx)
                return ERR_PTR(-ENOMEM);
 
-       hctxs = kmalloc_node(reg->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
-                       reg->numa_node);
+       hctxs = kmalloc_node(set->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
+                       set->numa_node);
 
        if (!hctxs)
                goto err_percpu;
 
-       for (i = 0; i < reg->nr_hw_queues; i++) {
-               hctxs[i] = reg->ops->alloc_hctx(reg, i);
+       for (i = 0; i < set->nr_hw_queues; i++) {
+               hctxs[i] = set->ops->alloc_hctx(set, i);
                if (!hctxs[i])
                        goto err_hctxs;
 
@@ -1337,11 +1367,11 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
                hctxs[i]->queue_num = i;
        }
 
-       q = blk_alloc_queue_node(GFP_KERNEL, reg->numa_node);
+       q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
        if (!q)
                goto err_hctxs;
 
-       q->mq_map = blk_mq_make_queue_map(reg);
+       q->mq_map = blk_mq_make_queue_map(set);
        if (!q->mq_map)
                goto err_map;
 
@@ -1349,33 +1379,34 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
        blk_queue_rq_timeout(q, 30000);
 
        q->nr_queues = nr_cpu_ids;
-       q->nr_hw_queues = reg->nr_hw_queues;
+       q->nr_hw_queues = set->nr_hw_queues;
 
        q->queue_ctx = ctx;
        q->queue_hw_ctx = hctxs;
 
-       q->mq_ops = reg->ops;
+       q->mq_ops = set->ops;
        q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 
        q->sg_reserved_size = INT_MAX;
 
        blk_queue_make_request(q, blk_mq_make_request);
-       blk_queue_rq_timed_out(q, reg->ops->timeout);
-       if (reg->timeout)
-               blk_queue_rq_timeout(q, reg->timeout);
+       blk_queue_rq_timed_out(q, set->ops->timeout);
+       if (set->timeout)
+               blk_queue_rq_timeout(q, set->timeout);
 
-       if (reg->ops->complete)
-               blk_queue_softirq_done(q, reg->ops->complete);
+       if (set->ops->complete)
+               blk_queue_softirq_done(q, set->ops->complete);
 
        blk_mq_init_flush(q);
-       blk_mq_init_cpu_queues(q, reg->nr_hw_queues);
+       blk_mq_init_cpu_queues(q, set->nr_hw_queues);
 
-       q->flush_rq = kzalloc(round_up(sizeof(struct request) + reg->cmd_size,
-                               cache_line_size()), GFP_KERNEL);
+       q->flush_rq = kzalloc(round_up(sizeof(struct request) +
+                               set->cmd_size, cache_line_size()),
+                               GFP_KERNEL);
        if (!q->flush_rq)
                goto err_hw;
 
-       if (blk_mq_init_hw_queues(q, reg, driver_data))
+       if (blk_mq_init_hw_queues(q, set))
                goto err_flush_rq;
 
        blk_mq_map_swqueue(q);
@@ -1393,11 +1424,11 @@ err_hw:
 err_map:
        blk_cleanup_queue(q);
 err_hctxs:
-       for (i = 0; i < reg->nr_hw_queues; i++) {
+       for (i = 0; i < set->nr_hw_queues; i++) {
                if (!hctxs[i])
                        break;
                free_cpumask_var(hctxs[i]->cpumask);
-               reg->ops->free_hctx(hctxs[i], i);
+               set->ops->free_hctx(hctxs[i], i);
        }
        kfree(hctxs);
 err_percpu:
@@ -1414,7 +1445,6 @@ void blk_mq_free_queue(struct request_queue *q)
        queue_for_each_hw_ctx(q, hctx, i) {
                kfree(hctx->ctx_map);
                kfree(hctx->ctxs);
-               blk_mq_free_rq_map(hctx, q->queuedata);
                blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
                if (q->mq_ops->exit_hctx)
                        q->mq_ops->exit_hctx(hctx, i);
@@ -1475,6 +1505,53 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
        return NOTIFY_OK;
 }
 
+int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
+{
+       int i;
+
+       if (!set->nr_hw_queues)
+               return -EINVAL;
+       if (!set->queue_depth || set->queue_depth > BLK_MQ_MAX_DEPTH)
+               return -EINVAL;
+       if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
+               return -EINVAL;
+
+       if (!set->nr_hw_queues ||
+           !set->ops->queue_rq || !set->ops->map_queue ||
+           !set->ops->alloc_hctx || !set->ops->free_hctx)
+               return -EINVAL;
+
+
+       set->tags = kmalloc_node(set->nr_hw_queues * sizeof(struct blk_mq_tags),
+                                GFP_KERNEL, set->numa_node);
+       if (!set->tags)
+               goto out;
+
+       for (i = 0; i < set->nr_hw_queues; i++) {
+               set->tags[i] = blk_mq_init_rq_map(set, i);
+               if (!set->tags[i])
+                       goto out_unwind;
+       }
+
+       return 0;
+
+out_unwind:
+       while (--i >= 0)
+               blk_mq_free_rq_map(set, set->tags[i], i);
+out:
+       return -ENOMEM;
+}
+EXPORT_SYMBOL(blk_mq_alloc_tag_set);
+
+void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
+{
+       int i;
+
+       for (i = 0; i < set->nr_hw_queues; i++)
+               blk_mq_free_rq_map(set, set->tags[i], i);
+}
+EXPORT_SYMBOL(blk_mq_free_tag_set);
+
 void blk_mq_disable_hotplug(void)
 {
        mutex_lock(&all_q_mutex);