null_blk: refactor init and init errors code paths

Simplify the initialization logic of the three block-layers.

- The queue initialization is split into two parts. This allows reuse of
  code when initializing the sq-, bio- and mq-based layers.
- Set submit_queues default value to 0 and always set it at init time.
- Simplify the init error code paths.

Signed-off-by: Matias Bjorling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 38 insertions, 25 deletions

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index f370fc13aea5..f0aeb2a7a9ca 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -65,7 +65,7 @@ enum {
         NULL_Q_MQ               = 2,
 };
 
-static int submit_queues = 1;
+static int submit_queues;
 module_param(submit_queues, int, S_IRUGO);
 MODULE_PARM_DESC(submit_queues, "Number of submission queues");
 
@@ -355,16 +355,24 @@ static void null_free_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_index)
         kfree(hctx);
 }
 
+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];
 
-        init_waitqueue_head(&nq->wait);
-        nq->queue_depth = nullb->queue_depth;
-        nullb->nr_queues++;
         hctx->driver_data = nq;
+        null_init_queue(nullb, nq);
+        nullb->nr_queues++;
 
         return 0;
 }
@@ -417,13 +425,13 @@ static int setup_commands(struct nullb_queue *nq)
 
         nq->cmds = kzalloc(nq->queue_depth * sizeof(*cmd), GFP_KERNEL);
         if (!nq->cmds)
-                return 1;
+                return -ENOMEM;
 
         tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
         nq->tag_map = kzalloc(tag_size * sizeof(unsigned long), GFP_KERNEL);
         if (!nq->tag_map) {
                 kfree(nq->cmds);
-                return 1;
+                return -ENOMEM;
         }
 
         for (i = 0; i < nq->queue_depth; i++) {
@@ -454,33 +462,37 @@ static void cleanup_queues(struct nullb *nullb)
 
 static int setup_queues(struct nullb *nullb)
 {
-        struct nullb_queue *nq;
-        int i;
-
-        nullb->queues = kzalloc(submit_queues * sizeof(*nq), GFP_KERNEL);
+        nullb->queues = kzalloc(submit_queues * sizeof(struct nullb_queue),
+                                                                GFP_KERNEL);
         if (!nullb->queues)
-                return 1;
+                return -ENOMEM;
 
         nullb->nr_queues = 0;
         nullb->queue_depth = hw_queue_depth;
 
-        if (queue_mode == NULL_Q_MQ)
-                return 0;
+        return 0;
+}
+
+static int init_driver_queues(struct nullb *nullb)
+{
+        struct nullb_queue *nq;
+        int i, ret = 0;
 
         for (i = 0; i < submit_queues; i++) {
                 nq = &nullb->queues[i];
-                init_waitqueue_head(&nq->wait);
-                nq->queue_depth = hw_queue_depth;
-                if (setup_commands(nq))
-                        break;
+
+                null_init_queue(nullb, nq);
+
+                ret = setup_commands(nq);
+                if (ret)
+                        goto err_queue;
                 nullb->nr_queues++;
         }
 
-        if (i == submit_queues)
-                return 0;
-
+        return 0;
+err_queue:
         cleanup_queues(nullb);
-        return 1;
+        return ret;
 }
 
 static int null_add_dev(void)
@@ -495,9 +507,6 @@ static int null_add_dev(void)
 
         spin_lock_init(&nullb->lock);
 
-        if (queue_mode == NULL_Q_MQ && use_per_node_hctx)
-                submit_queues = nr_online_nodes;
-
         if (setup_queues(nullb))
                 goto err;
 
@@ -518,11 +527,13 @@ static int null_add_dev(void)
         } else if (queue_mode == NULL_Q_BIO) {
                 nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node);
                 blk_queue_make_request(nullb->q, null_queue_bio);
+                init_driver_queues(nullb);
         } else {
                 nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock, home_node);
                 blk_queue_prep_rq(nullb->q, null_rq_prep_fn);
                 if (nullb->q)
                         blk_queue_softirq_done(nullb->q, null_softirq_done_fn);
+                init_driver_queues(nullb);
         }
 
         if (!nullb->q)
@@ -579,7 +590,9 @@ static int __init null_init(void)
         }
 #endif
 
-        if (submit_queues > nr_cpu_ids)
+        if (queue_mode == NULL_Q_MQ && use_per_node_hctx)
+                submit_queues = nr_online_nodes;
+        else if (submit_queues > nr_cpu_ids)
                 submit_queues = nr_cpu_ids;
         else if (!submit_queues)
                 submit_queues = 1;