rbd: a few simple changes

Here are a few very simple cleanups:
    - Add a "RBD_" prefix to the two driver name string definitions.
    - Move the definition of struct rbd_request below struct rbd_req_coll
      to avoid the need for an empty declaration of the latter.
    - Move and group the definitions of rbd_root_dev_release() and
      rbd_root_dev, as well as rbd_bus_type and rbd_bus_attrs[],
      close to the top of the file.  Arrange the latter so
      rbd_bus_type.bus_attrs can be initialized statically.
    - Get rid of an unnecessary local variable in rbd_open().
    - Rework some hokey logic in rbd_bus_add_dev(), so the value of
      "ret" at the end is either 0 or -ENOENT to avoid the need for
      the code duplication that was there.
    - Rename a goto target in rbd_add().
Signed-off-by: Alex Elder <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>

drivers/block/rbd.c

@@ -41,8 +41,8 @@
 
 #include "rbd_types.h"
 
-#define DRV_NAME "rbd"
-#define DRV_NAME_LONG "rbd (rados block device)"
+#define RBD_DRV_NAME "rbd"
+#define RBD_DRV_NAME_LONG "rbd (rados block device)"
 
 #define RBD_MINORS_PER_MAJOR	256		/* max minors per blkdev */
 
@@ -83,7 +83,7 @@ struct rbd_options {
 };
 
 /*
- * an instance of the client.  multiple devices may share a client.
+ * an instance of the client.  multiple devices may share an rbd client.
  */
 struct rbd_client {
 	struct ceph_client	*client;
@@ -92,20 +92,9 @@ struct rbd_client {
 	struct list_head	node;
 };
 
-struct rbd_req_coll;
-
 /*
- * a single io request
+ * a request completion status
  */
-struct rbd_request {
-	struct request		*rq;		/* blk layer request */
-	struct bio		*bio;		/* cloned bio */
-	struct page		**pages;	/* list of used pages */
-	u64			len;
-	int			coll_index;
-	struct rbd_req_coll	*coll;
-};
-
 struct rbd_req_status {
 	int done;
 	int rc;
@@ -122,6 +111,18 @@ struct rbd_req_coll {
 	struct rbd_req_status	status[0];
 };
 
+/*
+ * a single io request
+ */
+struct rbd_request {
+	struct request		*rq;		/* blk layer request */
+	struct bio		*bio;		/* cloned bio */
+	struct page		**pages;	/* list of used pages */
+	u64			len;
+	int			coll_index;
+	struct rbd_req_coll	*coll;
+};
+
 struct rbd_snap {
 	struct	device		dev;
 	const char		*name;
@@ -170,10 +171,6 @@ struct rbd_device {
 	struct device		dev;
 };
 
-static struct bus_type rbd_bus_type = {
-	.name		= "rbd",
-};
-
 static DEFINE_MUTEX(ctl_mutex);	  /* Serialize open/close/setup/teardown */
 
 static LIST_HEAD(rbd_dev_list);    /* devices */
@@ -191,6 +188,31 @@ static ssize_t rbd_snap_add(struct device *dev,
 static void __rbd_remove_snap_dev(struct rbd_device *rbd_dev,
 				  struct rbd_snap *snap);
 
+static ssize_t rbd_add(struct bus_type *bus, const char *buf,
+		       size_t count);
+static ssize_t rbd_remove(struct bus_type *bus, const char *buf,
+			  size_t count);
+
+static struct bus_attribute rbd_bus_attrs[] = {
+	__ATTR(add, S_IWUSR, NULL, rbd_add),
+	__ATTR(remove, S_IWUSR, NULL, rbd_remove),
+	__ATTR_NULL
+};
+
+static struct bus_type rbd_bus_type = {
+	.name		= "rbd",
+	.bus_attrs	= rbd_bus_attrs,
+};
+
+static void rbd_root_dev_release(struct device *dev)
+{
+}
+
+static struct device rbd_root_dev = {
+	.init_name =    "rbd",
+	.release =      rbd_root_dev_release,
+};
+
 
 static struct rbd_device *dev_to_rbd(struct device *dev)
 {
@@ -211,8 +233,7 @@ static int __rbd_update_snaps(struct rbd_device *rbd_dev);
 
 static int rbd_open(struct block_device *bdev, fmode_t mode)
 {
-	struct gendisk *disk = bdev->bd_disk;
-	struct rbd_device *rbd_dev = disk->private_data;
+	struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
 
 	rbd_get_dev(rbd_dev);
 
@@ -1216,8 +1237,8 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
 	rc = __rbd_update_snaps(dev);
 	mutex_unlock(&ctl_mutex);
 	if (rc)
-		pr_warning(DRV_NAME "%d got notification but failed to update"
-			   " snaps: %d\n", dev->major, rc);
+		pr_warning(RBD_DRV_NAME "%d got notification but failed to "
+			   " update snaps: %d\n", dev->major, rc);
 
 	rbd_req_sync_notify_ack(dev, ver, notify_id, dev->obj_md_name);
 }
@@ -1747,7 +1768,7 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 	if (!disk)
 		goto out;
 
-	snprintf(disk->disk_name, sizeof(disk->disk_name), DRV_NAME "%d",
+	snprintf(disk->disk_name, sizeof(disk->disk_name), RBD_DRV_NAME "%d",
 		 rbd_dev->id);
 	disk->major = rbd_dev->major;
 	disk->first_minor = 0;
@@ -2093,19 +2114,9 @@ static int __rbd_init_snaps_header(struct rbd_device *rbd_dev)
 	return 0;
 }
 
-
-static void rbd_root_dev_release(struct device *dev)
-{
-}
-
-static struct device rbd_root_dev = {
-	.init_name =    "rbd",
-	.release =      rbd_root_dev_release,
-};
-
 static int rbd_bus_add_dev(struct rbd_device *rbd_dev)
 {
-	int ret = -ENOMEM;
+	int ret;
 	struct device *dev;
 	struct rbd_snap *snap;
 
@@ -2119,7 +2130,7 @@ static int rbd_bus_add_dev(struct rbd_device *rbd_dev)
 	dev_set_name(dev, "%d", rbd_dev->id);
 	ret = device_register(dev);
 	if (ret < 0)
-		goto done_free;
+		goto out;
 
 	list_for_each_entry(snap, &rbd_dev->snaps, node) {
 		ret = rbd_register_snap_dev(rbd_dev, snap,
@@ -2127,10 +2138,7 @@ static int rbd_bus_add_dev(struct rbd_device *rbd_dev)
 		if (ret < 0)
 			break;
 	}
-
-	mutex_unlock(&ctl_mutex);
-	return 0;
-done_free:
+out:
 	mutex_unlock(&ctl_mutex);
 	return ret;
 }
@@ -2268,7 +2276,7 @@ static ssize_t rbd_add(struct bus_type *bus,
 		   mon_dev_name, options, rbd_dev->pool_name,
 		   rbd_dev->obj, rbd_dev->snap_name) < 4) {
 		rc = -EINVAL;
-		goto err_out_slot;
+		goto err_put_id;
 	}
 
 	if (rbd_dev->snap_name[0] == 0)
@@ -2280,11 +2288,11 @@ static ssize_t rbd_add(struct bus_type *bus,
 		 rbd_dev->obj, RBD_SUFFIX);
 
 	/* initialize rest of new object */
-	snprintf(rbd_dev->name, DEV_NAME_LEN, DRV_NAME "%d", rbd_dev->id);
+	snprintf(rbd_dev->name, DEV_NAME_LEN, RBD_DRV_NAME "%d", rbd_dev->id);
 
 	rc = rbd_get_client(rbd_dev, mon_dev_name, options);
 	if (rc < 0)
-		goto err_out_slot;
+		goto err_put_id;
 
 	/* pick the pool */
 	osdc = &rbd_dev->rbd_client->client->osdc;
@@ -2330,9 +2338,8 @@ static ssize_t rbd_add(struct bus_type *bus,
 	unregister_blkdev(rbd_dev->major, rbd_dev->name);
 err_out_client:
 	rbd_put_client(rbd_dev);
-err_out_slot:
+err_put_id:
 	rbd_id_put(rbd_dev);
-
 	kfree(rbd_dev);
 err_out_opt:
 	kfree(options);
@@ -2463,12 +2470,6 @@ static ssize_t rbd_snap_add(struct device *dev,
 	return ret;
 }
 
-static struct bus_attribute rbd_bus_attrs[] = {
-	__ATTR(add, S_IWUSR, NULL, rbd_add),
-	__ATTR(remove, S_IWUSR, NULL, rbd_remove),
-	__ATTR_NULL
-};
-
 /*
  * create control files in sysfs
  * /sys/bus/rbd/...
@@ -2477,8 +2478,6 @@ static int rbd_sysfs_init(void)
 {
 	int ret;
 
-	rbd_bus_type.bus_attrs = rbd_bus_attrs;
-
 	ret = bus_register(&rbd_bus_type);
 	if (ret < 0)
 		return ret;
@@ -2501,7 +2500,7 @@ int __init rbd_init(void)
 	rc = rbd_sysfs_init();
 	if (rc)
 		return rc;
-	pr_info("loaded " DRV_NAME_LONG "\n");
+	pr_info("loaded " RBD_DRV_NAME_LONG "\n");
 	return 0;
 }