blk-mq: make the sysfs mq/ layout reflect current mappings

Currently blk-mq registers all the hardware queues in sysfs,
regardless of whether it uses them (e.g. they have CPU mappings)
or not. The unused hardware queues lack the cpux/ directories,
and the other sysfs entries (like active, pending, etc) are all
zeroes.

Change this so that sysfs correctly reflects the current mappings
of the hardware queues.

Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 99a60a8..e5f575f 100644 (file)
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -327,6 +327,42 @@ static struct kobj_type blk_mq_hw_ktype = {
        .release        = blk_mq_sysfs_release,
 };
 
+void blk_mq_unregister_hctx(struct blk_mq_hw_ctx *hctx)
+{
+       struct blk_mq_ctx *ctx;
+       int i;
+
+       if (!hctx->nr_ctx || !(hctx->flags & BLK_MQ_F_SYSFS_UP))
+               return;
+
+       hctx_for_each_ctx(hctx, ctx, i)
+               kobject_del(&ctx->kobj);
+
+       kobject_del(&hctx->kobj);
+}
+
+int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx)
+{
+       struct request_queue *q = hctx->queue;
+       struct blk_mq_ctx *ctx;
+       int i, ret;
+
+       if (!hctx->nr_ctx || !(hctx->flags & BLK_MQ_F_SYSFS_UP))
+               return 0;
+
+       ret = kobject_add(&hctx->kobj, &q->mq_kobj, "%u", hctx->queue_num);
+       if (ret)
+               return ret;
+
+       hctx_for_each_ctx(hctx, ctx, i) {
+               ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu);
+               if (ret)
+                       break;
+       }
+
+       return ret;
+}
+
 void blk_mq_unregister_disk(struct gendisk *disk)
 {
        struct request_queue *q = disk->queue;
@@ -335,11 +371,11 @@ void blk_mq_unregister_disk(struct gendisk *disk)
        int i, j;
 
        queue_for_each_hw_ctx(q, hctx, i) {
-               hctx_for_each_ctx(hctx, ctx, j) {
-                       kobject_del(&ctx->kobj);
+               blk_mq_unregister_hctx(hctx);
+
+               hctx_for_each_ctx(hctx, ctx, j)
                        kobject_put(&ctx->kobj);
-               }
-               kobject_del(&hctx->kobj);
+
                kobject_put(&hctx->kobj);
        }
 
@@ -350,15 +386,30 @@ void blk_mq_unregister_disk(struct gendisk *disk)
        kobject_put(&disk_to_dev(disk)->kobj);
 }
 
+static void blk_mq_sysfs_init(struct request_queue *q)
+{
+       struct blk_mq_hw_ctx *hctx;
+       struct blk_mq_ctx *ctx;
+       int i, j;
+
+       kobject_init(&q->mq_kobj, &blk_mq_ktype);
+
+       queue_for_each_hw_ctx(q, hctx, i) {
+               kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
+
+               hctx_for_each_ctx(hctx, ctx, j)
+                       kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
+       }
+}
+
 int blk_mq_register_disk(struct gendisk *disk)
 {
        struct device *dev = disk_to_dev(disk);
        struct request_queue *q = disk->queue;
        struct blk_mq_hw_ctx *hctx;
-       struct blk_mq_ctx *ctx;
-       int ret, i, j;
+       int ret, i;
 
-       kobject_init(&q->mq_kobj, &blk_mq_ktype);
+       blk_mq_sysfs_init(q);
 
        ret = kobject_add(&q->mq_kobj, kobject_get(&dev->kobj), "%s", "mq");
        if (ret < 0)
@@ -367,20 +418,10 @@ int blk_mq_register_disk(struct gendisk *disk)
        kobject_uevent(&q->mq_kobj, KOBJ_ADD);
 
        queue_for_each_hw_ctx(q, hctx, i) {
-               kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
-               ret = kobject_add(&hctx->kobj, &q->mq_kobj, "%u", i);
+               hctx->flags |= BLK_MQ_F_SYSFS_UP;
+               ret = blk_mq_register_hctx(hctx);
                if (ret)
                        break;
-
-               if (!hctx->nr_ctx)
-                       continue;
-
-               hctx_for_each_ctx(hctx, ctx, j) {
-                       kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
-                       ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu);
-                       if (ret)
-                               break;
-               }
        }
 
        if (ret) {
@@ -390,3 +431,26 @@ int blk_mq_register_disk(struct gendisk *disk)
 
        return 0;
 }
+
+void blk_mq_sysfs_unregister(struct request_queue *q)
+{
+       struct blk_mq_hw_ctx *hctx;
+       int i;
+
+       queue_for_each_hw_ctx(q, hctx, i)
+               blk_mq_unregister_hctx(hctx);
+}
+
+int blk_mq_sysfs_register(struct request_queue *q)
+{
+       struct blk_mq_hw_ctx *hctx;
+       int i, ret = 0;
+
+       queue_for_each_hw_ctx(q, hctx, i) {
+               ret = blk_mq_register_hctx(hctx);
+               if (ret)
+                       break;
+       }
+
+       return ret;
+}

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 21f952a..71f564e 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1924,6 +1924,8 @@ static void blk_mq_queue_reinit(struct request_queue *q)
 {
        blk_mq_freeze_queue(q);
 
+       blk_mq_sysfs_unregister(q);
+
        blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
 
        /*
@@ -1934,6 +1936,8 @@ static void blk_mq_queue_reinit(struct request_queue *q)
 
        blk_mq_map_swqueue(q);
 
+       blk_mq_sysfs_register(q);
+
        blk_mq_unfreeze_queue(q);
 }
 

diff --git a/block/blk-mq.h b/block/blk-mq.h
index ff5e6bf..de7b3bb 100644 (file)
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -55,6 +55,12 @@ extern int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues);
 extern int blk_mq_hw_queue_to_node(unsigned int *map, unsigned int);
 
 /*
+ * sysfs helpers
+ */
+extern int blk_mq_sysfs_register(struct request_queue *q);
+extern void blk_mq_sysfs_unregister(struct request_queue *q);
+
+/*
  * Basic implementation of sparser bitmap, allowing the user to spread
  * the bits over more cachelines.
  */

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index ad3adb7..c151288 100644 (file)
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -130,6 +130,7 @@ enum {
        BLK_MQ_F_SHOULD_SORT    = 1 << 1,
        BLK_MQ_F_TAG_SHARED     = 1 << 2,
        BLK_MQ_F_SG_MERGE       = 1 << 3,
+       BLK_MQ_F_SYSFS_UP       = 1 << 4,
 
        BLK_MQ_S_STOPPED        = 0,
        BLK_MQ_S_TAG_ACTIVE     = 1,