1 files changed, 70 insertions, 42 deletions

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 586dfff5d53f..71f4422eba81 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -35,7 +35,8 @@ struct nullb {
         struct request_queue *q;
         struct gendisk *disk;
         struct nvm_dev *ndev;
-        struct blk_mq_tag_set tag_set;
+        struct blk_mq_tag_set *tag_set;
+        struct blk_mq_tag_set __tag_set;
         struct hrtimer timer;
         unsigned int queue_depth;
         spinlock_t lock;
@@ -50,6 +51,7 @@ static struct mutex lock;
 static int null_major;
 static int nullb_indexes;
 static struct kmem_cache *ppa_cache;
+static struct blk_mq_tag_set tag_set;
 
 enum {
         NULL_IRQ_NONE           = 0,
@@ -109,7 +111,7 @@ static int bs = 512;
 module_param(bs, int, S_IRUGO);
 MODULE_PARM_DESC(bs, "Block size (in bytes)");
 
-static int nr_devices = 2;
+static int nr_devices = 1;
 module_param(nr_devices, int, S_IRUGO);
 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
 
@@ -121,6 +123,10 @@ static bool blocking;
 module_param(blocking, bool, S_IRUGO);
 MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
 
+static bool shared_tags;
+module_param(shared_tags, bool, S_IRUGO);
+MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq");
+
 static int irqmode = NULL_IRQ_SOFTIRQ;
 
 static int null_set_irqmode(const char *str, const struct kernel_param *kp)
@@ -376,31 +382,8 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
         return BLK_STS_OK;
 }
 
-static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
-{
-        BUG_ON(!nullb);
-        BUG_ON(!nq);
-
-        init_waitqueue_head(&nq->wait);
-        nq->queue_depth = nullb->queue_depth;
-}
-
-static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
-                          unsigned int index)
-{
-        struct nullb *nullb = data;
-        struct nullb_queue *nq = &nullb->queues[index];
-
-        hctx->driver_data = nq;
-        null_init_queue(nullb, nq);
-        nullb->nr_queues++;
-
-        return 0;
-}
-
 static const struct blk_mq_ops null_mq_ops = {
         .queue_rq       = null_queue_rq,
-        .init_hctx      = null_init_hctx,
         .complete       = null_softirq_done_fn,
 };
 
@@ -592,8 +575,8 @@ static void null_del_dev(struct nullb *nullb)
         else
                 del_gendisk(nullb->disk);
         blk_cleanup_queue(nullb->q);
-        if (queue_mode == NULL_Q_MQ)
-                blk_mq_free_tag_set(&nullb->tag_set);
+        if (queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
+                blk_mq_free_tag_set(nullb->tag_set);
         if (!use_lightnvm)
                 put_disk(nullb->disk);
         cleanup_queues(nullb);
@@ -615,6 +598,32 @@ static const struct block_device_operations null_fops = {
         .release =      null_release,
 };
 
+static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
+{
+        BUG_ON(!nullb);
+        BUG_ON(!nq);
+
+        init_waitqueue_head(&nq->wait);
+        nq->queue_depth = nullb->queue_depth;
+}
+
+static void null_init_queues(struct nullb *nullb)
+{
+        struct request_queue *q = nullb->q;
+        struct blk_mq_hw_ctx *hctx;
+        struct nullb_queue *nq;
+        int i;
+
+        queue_for_each_hw_ctx(q, hctx, i) {
+                if (!hctx->nr_ctx || !hctx->tags)
+                        continue;
+                nq = &nullb->queues[i];
+                hctx->driver_data = nq;
+                null_init_queue(nullb, nq);
+                nullb->nr_queues++;
+        }
+}
+
 static int setup_commands(struct nullb_queue *nq)
 {
         struct nullb_cmd *cmd;
@@ -695,6 +704,22 @@ static int null_gendisk_register(struct nullb *nullb)
         return 0;
 }
 
+static int null_init_tag_set(struct blk_mq_tag_set *set)
+{
+        set->ops = &null_mq_ops;
+        set->nr_hw_queues = submit_queues;
+        set->queue_depth = hw_queue_depth;
+        set->numa_node = home_node;
+        set->cmd_size   = sizeof(struct nullb_cmd);
+        set->flags = BLK_MQ_F_SHOULD_MERGE;
+        set->driver_data = NULL;
+
+        if (blocking)
+                set->flags |= BLK_MQ_F_BLOCKING;
+
+        return blk_mq_alloc_tag_set(set);
+}
+
 static int null_add_dev(void)
 {
         struct nullb *nullb;
@@ -716,26 +741,23 @@ static int null_add_dev(void)
                 goto out_free_nullb;
 
         if (queue_mode == NULL_Q_MQ) {
-                nullb->tag_set.ops = &null_mq_ops;
-                nullb->tag_set.nr_hw_queues = submit_queues;
-                nullb->tag_set.queue_depth = hw_queue_depth;
-                nullb->tag_set.numa_node = home_node;
-                nullb->tag_set.cmd_size = sizeof(struct nullb_cmd);
-                nullb->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
-                nullb->tag_set.driver_data = nullb;
-
-                if (blocking)
-                        nullb->tag_set.flags |= BLK_MQ_F_BLOCKING;
-
-                rv = blk_mq_alloc_tag_set(&nullb->tag_set);
+                if (shared_tags) {
+                        nullb->tag_set = &tag_set;
+                        rv = 0;
+                } else {
+                        nullb->tag_set = &nullb->__tag_set;
+                        rv = null_init_tag_set(nullb->tag_set);
+                }
+
                 if (rv)
                         goto out_cleanup_queues;
 
-                nullb->q = blk_mq_init_queue(&nullb->tag_set);
+                nullb->q = blk_mq_init_queue(nullb->tag_set);
                 if (IS_ERR(nullb->q)) {
                         rv = -ENOMEM;
                         goto out_cleanup_tags;
                 }
+                null_init_queues(nullb);
         } else if (queue_mode == NULL_Q_BIO) {
                 nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node);
                 if (!nullb->q) {
@@ -788,8 +810,8 @@ static int null_add_dev(void)
 out_cleanup_blk_queue:
         blk_cleanup_queue(nullb->q);
 out_cleanup_tags:
-        if (queue_mode == NULL_Q_MQ)
-                blk_mq_free_tag_set(&nullb->tag_set);
+        if (queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
+                blk_mq_free_tag_set(nullb->tag_set);
 out_cleanup_queues:
         cleanup_queues(nullb);
 out_free_nullb:
@@ -822,6 +844,9 @@ static int __init null_init(void)
                 queue_mode = NULL_Q_MQ;
         }
 
+        if (queue_mode == NULL_Q_MQ && shared_tags)
+                null_init_tag_set(&tag_set);
+
         if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
                 if (submit_queues < nr_online_nodes) {
                         pr_warn("null_blk: submit_queues param is set to %u.",
@@ -882,6 +907,9 @@ static void __exit null_exit(void)
         }
         mutex_unlock(&lock);
 
+        if (queue_mode == NULL_Q_MQ && shared_tags)
+                blk_mq_free_tag_set(&tag_set);
+
         kmem_cache_destroy(ppa_cache);
 }