rbd: introduce a per-device ordered workqueue

This is going to be used for re-registering watch requests and
exclusive-lock tasks: acquire/request lock, notify-acquired, release
lock, notify-released.  Some refactoring in the map/unmap paths was
necessary to give this workqueue a meaningful name: "rbdX-tasks".

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>

1 files changed, 71 insertions, 80 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index e0585e9040f1..1c805eea6767 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -128,11 +128,8 @@ static int atomic_dec_return_safe(atomic_t *v)
 /*
  * An RBD device name will be "rbd#", where the "rbd" comes from
  * RBD_DRV_NAME above, and # is a unique integer identifier.
- * MAX_INT_FORMAT_WIDTH is used in ensuring DEV_NAME_LEN is big
- * enough to hold all possible device names.
  */
 #define DEV_NAME_LEN            32
-#define MAX_INT_FORMAT_WIDTH    ((5 * sizeof (int)) / 2 + 1)
 
 /*
  * block device image metadata (in-memory version)
@@ -353,10 +350,12 @@ struct rbd_device {
         struct ceph_object_id   header_oid;
         struct ceph_object_locator header_oloc;
 
-        struct ceph_file_layout layout;
+        struct ceph_file_layout layout;         /* used for all rbd requests */
 
         struct ceph_osd_linger_request *watch_handle;
 
+        struct workqueue_struct *task_wq;
+
         struct rbd_spec         *parent_spec;
         u64                     parent_overlap;
         atomic_t                parent_ref;
@@ -3944,11 +3943,8 @@ static void rbd_spec_free(struct kref *kref)
         kfree(spec);
 }
 
-static void rbd_dev_release(struct device *dev)
+static void rbd_dev_free(struct rbd_device *rbd_dev)
 {
-        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
-        bool need_put = !!rbd_dev->opts;
-
         ceph_oid_destroy(&rbd_dev->header_oid);
         ceph_oloc_destroy(&rbd_dev->header_oloc);
 
@@ -3956,6 +3952,19 @@ static void rbd_dev_release(struct device *dev)
         rbd_spec_put(rbd_dev->spec);
         kfree(rbd_dev->opts);
         kfree(rbd_dev);
+}
+
+static void rbd_dev_release(struct device *dev)
+{
+        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+        bool need_put = !!rbd_dev->opts;
+
+        if (need_put) {
+                destroy_workqueue(rbd_dev->task_wq);
+                ida_simple_remove(&rbd_dev_id_ida, rbd_dev->dev_id);
+        }
+
+        rbd_dev_free(rbd_dev);
 
         /*
          * This is racy, but way better than putting module outside of
@@ -3966,19 +3975,16 @@ static void rbd_dev_release(struct device *dev)
                 module_put(THIS_MODULE);
 }
 
-static struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
-                                         struct rbd_spec *spec,
-                                         struct rbd_options *opts)
+static struct rbd_device *__rbd_dev_create(struct rbd_client *rbdc,
+                                           struct rbd_spec *spec)
 {
         struct rbd_device *rbd_dev;
 
-        rbd_dev = kzalloc(sizeof (*rbd_dev), GFP_KERNEL);
+        rbd_dev = kzalloc(sizeof(*rbd_dev), GFP_KERNEL);
         if (!rbd_dev)
                 return NULL;
 
         spin_lock_init(&rbd_dev->lock);
-        rbd_dev->flags = 0;
-        atomic_set(&rbd_dev->parent_ref, 0);
         INIT_LIST_HEAD(&rbd_dev->node);
         init_rwsem(&rbd_dev->header_rwsem);
 
@@ -3992,9 +3998,6 @@ static struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
 
         rbd_dev->rbd_client = rbdc;
         rbd_dev->spec = spec;
-        rbd_dev->opts = opts;
-
-        /* Initialize the layout used for all rbd requests */
 
         rbd_dev->layout.stripe_unit = 1 << RBD_MAX_OBJ_ORDER;
         rbd_dev->layout.stripe_count = 1;
@@ -4002,15 +4005,48 @@ static struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
         rbd_dev->layout.pool_id = spec->pool_id;
         RCU_INIT_POINTER(rbd_dev->layout.pool_ns, NULL);
 
-        /*
-         * If this is a mapping rbd_dev (as opposed to a parent one),
-         * pin our module.  We have a ref from do_rbd_add(), so use
-         * __module_get().
-         */
-        if (rbd_dev->opts)
-                __module_get(THIS_MODULE);
+        return rbd_dev;
+}
+
+/*
+ * Create a mapping rbd_dev.
+ */
+static struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
+                                         struct rbd_spec *spec,
+                                         struct rbd_options *opts)
+{
+        struct rbd_device *rbd_dev;
+
+        rbd_dev = __rbd_dev_create(rbdc, spec);
+        if (!rbd_dev)
+                return NULL;
+
+        rbd_dev->opts = opts;
+
+        /* get an id and fill in device name */
+        rbd_dev->dev_id = ida_simple_get(&rbd_dev_id_ida, 0,
+                                         minor_to_rbd_dev_id(1 << MINORBITS),
+                                         GFP_KERNEL);
+        if (rbd_dev->dev_id < 0)
+                goto fail_rbd_dev;
+
+        sprintf(rbd_dev->name, RBD_DRV_NAME "%d", rbd_dev->dev_id);
+        rbd_dev->task_wq = alloc_ordered_workqueue("%s-tasks", WQ_MEM_RECLAIM,
+                                                   rbd_dev->name);
+        if (!rbd_dev->task_wq)
+                goto fail_dev_id;
 
+        /* we have a ref from do_rbd_add() */
+        __module_get(THIS_MODULE);
+
+        dout("%s rbd_dev %p dev_id %d\n", __func__, rbd_dev, rbd_dev->dev_id);
         return rbd_dev;
+
+fail_dev_id:
+        ida_simple_remove(&rbd_dev_id_ida, rbd_dev->dev_id);
+fail_rbd_dev:
+        rbd_dev_free(rbd_dev);
+        return NULL;
 }
 
 static void rbd_dev_destroy(struct rbd_device *rbd_dev)
@@ -4646,46 +4682,6 @@ static int rbd_dev_header_info(struct rbd_device *rbd_dev)
 }
 
 /*
- * Get a unique rbd identifier for the given new rbd_dev, and add
- * the rbd_dev to the global list.
- */
-static int rbd_dev_id_get(struct rbd_device *rbd_dev)
-{
-        int new_dev_id;
-
-        new_dev_id = ida_simple_get(&rbd_dev_id_ida,
-                                    0, minor_to_rbd_dev_id(1 << MINORBITS),
-                                    GFP_KERNEL);
-        if (new_dev_id < 0)
-                return new_dev_id;
-
-        rbd_dev->dev_id = new_dev_id;
-
-        spin_lock(&rbd_dev_list_lock);
-        list_add_tail(&rbd_dev->node, &rbd_dev_list);
-        spin_unlock(&rbd_dev_list_lock);
-
-        dout("rbd_dev %p given dev id %d\n", rbd_dev, rbd_dev->dev_id);
-
-        return 0;
-}
-
-/*
- * Remove an rbd_dev from the global list, and record that its
- * identifier is no longer in use.
- */
-static void rbd_dev_id_put(struct rbd_device *rbd_dev)
-{
-        spin_lock(&rbd_dev_list_lock);
-        list_del_init(&rbd_dev->node);
-        spin_unlock(&rbd_dev_list_lock);
-
-        ida_simple_remove(&rbd_dev_id_ida, rbd_dev->dev_id);
-
-        dout("rbd_dev %p released dev id %d\n", rbd_dev, rbd_dev->dev_id);
-}
-
-/*
  * Skips over white space at *buf, and updates *buf to point to the
  * first found non-space character (if any). Returns the length of
  * the token (string of non-white space characters) found.  Note
@@ -5077,8 +5073,7 @@ static int rbd_dev_probe_parent(struct rbd_device *rbd_dev, int depth)
                 goto out_err;
         }
 
-        parent = rbd_dev_create(rbd_dev->rbd_client, rbd_dev->parent_spec,
-                                NULL);
+        parent = __rbd_dev_create(rbd_dev->rbd_client, rbd_dev->parent_spec);
         if (!parent) {
                 ret = -ENOMEM;
                 goto out_err;
@@ -5113,22 +5108,12 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 {
         int ret;
 
-        /* Get an id and fill in device name. */
-
-        ret = rbd_dev_id_get(rbd_dev);
-        if (ret)
-                goto err_out_unlock;
-
-        BUILD_BUG_ON(DEV_NAME_LEN
-                        < sizeof (RBD_DRV_NAME) + MAX_INT_FORMAT_WIDTH);
-        sprintf(rbd_dev->name, "%s%d", RBD_DRV_NAME, rbd_dev->dev_id);
-
         /* Record our major and minor device numbers. */
 
         if (!single_major) {
                 ret = register_blkdev(0, rbd_dev->name);
                 if (ret < 0)
-                        goto err_out_id;
+                        goto err_out_unlock;
 
                 rbd_dev->major = ret;
                 rbd_dev->minor = 0;
@@ -5160,6 +5145,10 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
         set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
         up_write(&rbd_dev->header_rwsem);
 
+        spin_lock(&rbd_dev_list_lock);
+        list_add_tail(&rbd_dev->node, &rbd_dev_list);
+        spin_unlock(&rbd_dev_list_lock);
+
         add_disk(rbd_dev->disk);
         pr_info("%s: added with size 0x%llx\n", rbd_dev->disk->disk_name,
                 (unsigned long long) rbd_dev->mapping.size);
@@ -5173,8 +5162,6 @@ err_out_disk:
 err_out_blkdev:
         if (!single_major)
                 unregister_blkdev(rbd_dev->major, rbd_dev->name);
-err_out_id:
-        rbd_dev_id_put(rbd_dev);
 err_out_unlock:
         up_write(&rbd_dev->header_rwsem);
         return ret;
@@ -5406,12 +5393,16 @@ static ssize_t rbd_add_single_major(struct bus_type *bus,
 static void rbd_dev_device_release(struct rbd_device *rbd_dev)
 {
         rbd_free_disk(rbd_dev);
+
+        spin_lock(&rbd_dev_list_lock);
+        list_del_init(&rbd_dev->node);
+        spin_unlock(&rbd_dev_list_lock);
+
         clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
         device_del(&rbd_dev->dev);
         rbd_dev_mapping_clear(rbd_dev);
         if (!single_major)
                 unregister_blkdev(rbd_dev->major, rbd_dev->name);
-        rbd_dev_id_put(rbd_dev);
 }
 
 static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)