[PATCH 2/2] blk-mq: alloc q->queue_ctx as normal array

[Ming Lei]

Now q->queue_ctx is just one read-mostly table for query the
'blk_mq_ctx' instance from one cpu index, it isn't necessary
to allocate it as percpu variable. One simple array may be
more efficient.

Cc: Guenter Roeck <li...@roeck-us.net>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Ming Lei <ming....@redhat.com>
---
 block/blk-mq-sysfs.c   |  6 +++---
 block/blk-mq.c         | 12 +++++++-----
 block/blk-mq.h         |  2 +-
 include/linux/blkdev.h |  2 +-
 4 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index bab236955f56..dc4ac733a125 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -300,7 +300,7 @@ void blk_mq_sysfs_deinit(struct request_queue *q)
        int cpu;
 
        for_each_possible_cpu(cpu) {
-               ctx = *per_cpu_ptr(q->queue_ctx, cpu);
+               ctx = q->queue_ctx[cpu];
                kobject_put(&ctx->kobj);
        }
        kobject_put(q->mq_kobj);
@@ -322,7 +322,7 @@ int blk_mq_sysfs_init(struct request_queue *q)
                ctx = kzalloc_node(sizeof(*ctx), GFP_KERNEL, cpu_to_node(cpu));
                if (!ctx)
                        goto fail;
-               *per_cpu_ptr(q->queue_ctx, cpu) = ctx;
+               q->queue_ctx[cpu] = ctx;
                kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
        }
        q->mq_kobj = &mq_kobj->kobj;
@@ -330,7 +330,7 @@ int blk_mq_sysfs_init(struct request_queue *q)
 
  fail:
        for_each_possible_cpu(cpu) {
-               ctx = *per_cpu_ptr(q->queue_ctx, cpu);
+               ctx = q->queue_ctx[cpu];
                if (ctx)
                        kobject_put(&ctx->kobj);
        }
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3589ee601f37..20c485e1817a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2299,7 +2299,7 @@ static void blk_mq_init_cpu_queues(struct request_queue 
*q,
        unsigned int i, j;
 
        for_each_possible_cpu(i) {
-               struct blk_mq_ctx *__ctx = *per_cpu_ptr(q->queue_ctx, i);
+               struct blk_mq_ctx *__ctx = q->queue_ctx[i];
                struct blk_mq_hw_ctx *hctx;
 
                __ctx->cpu = i;
@@ -2385,7 +2385,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
                        set->map[0].mq_map[i] = 0;
                }
 
-               ctx = *per_cpu_ptr(q->queue_ctx, i);
+               ctx = q->queue_ctx[i];
                for (j = 0; j < set->nr_maps; j++) {
                        hctx = blk_mq_map_queue_type(q, j, i);
 
@@ -2541,7 +2541,7 @@ void blk_mq_release(struct request_queue *q)
         */
        blk_mq_sysfs_deinit(q);
 
-       free_percpu(q->queue_ctx);
+       kfree(q->queue_ctx);
 }
 
 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
@@ -2731,7 +2731,9 @@ struct request_queue *blk_mq_init_allocated_queue(struct 
blk_mq_tag_set *set,
        if (!q->poll_cb)
                goto err_exit;
 
-       q->queue_ctx = alloc_percpu(struct blk_mq_ctx *);
+       q->queue_ctx = kmalloc_array_node(nr_cpu_ids,
+                                         sizeof(struct blk_mq_ctx *),
+                                         GFP_KERNEL, set->numa_node);
        if (!q->queue_ctx)
                goto err_exit;
 
@@ -2798,7 +2800,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct 
blk_mq_tag_set *set,
 err_sys_init:
        blk_mq_sysfs_deinit(q);
 err_percpu:
-       free_percpu(q->queue_ctx);
+       kfree(q->queue_ctx);
 err_exit:
        q->mq_ops = NULL;
        return ERR_PTR(-ENOMEM);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 84898793c230..97829388e1db 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -129,7 +129,7 @@ static inline enum mq_rq_state blk_mq_rq_state(struct 
request *rq)
 static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
                                           unsigned int cpu)
 {
-       return *per_cpu_ptr(q->queue_ctx, cpu);
+       return q->queue_ctx[cpu];
 }
 
 /*
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9e3892bd67fd..9b6ddc5c7a40 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -407,7 +407,7 @@ struct request_queue {
        const struct blk_mq_ops *mq_ops;
 
        /* sw queues */
-       struct blk_mq_ctx __percpu      **queue_ctx;
+       struct blk_mq_ctx       **queue_ctx;
        unsigned int            nr_queues;
 
        unsigned int            queue_depth;
-- 
2.9.5