rbd: use a single workqueue for all devices

Using one queue per device doesn't make much sense given that our
workfn processes "devices" and not "requests".  Switch to a single
workqueue for all devices.

Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 0a54c588e433751f39084459193a5da7700d34db..be8d44af6ae1f559c306960cef03d9bc7ebb094d 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -342,7 +342,6 @@ struct rbd_device {
 
        struct list_head        rq_queue;       /* incoming rq queue */
        spinlock_t              lock;           /* queue, flags, open_count */
-       struct workqueue_struct *rq_wq;
        struct work_struct      rq_work;
 
        struct rbd_image_header header;
@@ -402,6 +401,8 @@ static struct kmem_cache    *rbd_segment_name_cache;
 static int rbd_major;
 static DEFINE_IDA(rbd_dev_id_ida);
 
+static struct workqueue_struct *rbd_wq;
+
 /*
  * Default to false for now, as single-major requires >= 0.75 version of
  * userspace rbd utility.
@@ -3452,7 +3453,7 @@ static void rbd_request_fn(struct request_queue *q)
        }
 
        if (queued)
-               queue_work(rbd_dev->rq_wq, &rbd_dev->rq_work);
+               queue_work(rbd_wq, &rbd_dev->rq_work);
 }
 
 /*
@@ -5242,16 +5243,9 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
        set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
        set_disk_ro(rbd_dev->disk, rbd_dev->mapping.read_only);
 
-       rbd_dev->rq_wq = alloc_workqueue("%s", WQ_MEM_RECLAIM, 0,
-                                        rbd_dev->disk->disk_name);
-       if (!rbd_dev->rq_wq) {
-               ret = -ENOMEM;
-               goto err_out_mapping;
-       }
-
        ret = rbd_bus_add_dev(rbd_dev);
        if (ret)
-               goto err_out_workqueue;
+               goto err_out_mapping;
 
        /* Everything's ready.  Announce the disk to the world. */
 
@@ -5263,9 +5257,6 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 
        return ret;
 
-err_out_workqueue:
-       destroy_workqueue(rbd_dev->rq_wq);
-       rbd_dev->rq_wq = NULL;
 err_out_mapping:
        rbd_dev_mapping_clear(rbd_dev);
 err_out_disk:
@@ -5512,7 +5503,6 @@ static void rbd_dev_device_release(struct device *dev)
 {
        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-       destroy_workqueue(rbd_dev->rq_wq);
        rbd_free_disk(rbd_dev);
        clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
        rbd_dev_mapping_clear(rbd_dev);
@@ -5716,11 +5706,21 @@ static int __init rbd_init(void)
        if (rc)
                return rc;
 
+       /*
+        * The number of active work items is limited by the number of
+        * rbd devices, so leave @max_active at default.
+        */
+       rbd_wq = alloc_workqueue(RBD_DRV_NAME, WQ_MEM_RECLAIM, 0);
+       if (!rbd_wq) {
+               rc = -ENOMEM;
+               goto err_out_slab;
+       }
+
        if (single_major) {
                rbd_major = register_blkdev(0, RBD_DRV_NAME);
                if (rbd_major < 0) {
                        rc = rbd_major;
-                       goto err_out_slab;
+                       goto err_out_wq;
                }
        }
 
@@ -5738,6 +5738,8 @@ static int __init rbd_init(void)
 err_out_blkdev:
        if (single_major)
                unregister_blkdev(rbd_major, RBD_DRV_NAME);
+err_out_wq:
+       destroy_workqueue(rbd_wq);
 err_out_slab:
        rbd_slab_exit();
        return rc;
@@ -5749,6 +5751,7 @@ static void __exit rbd_exit(void)
        rbd_sysfs_cleanup();
        if (single_major)
                unregister_blkdev(rbd_major, RBD_DRV_NAME);
+       destroy_workqueue(rbd_wq);
        rbd_slab_exit();
 }