rbd: tie rbd_dev_list changes to rbd_id operations
The only time entries are added to or removed from the global
rbd_dev_list is exactly when a "put" or "get" operation is being
performed on a rbd_dev's id. So just move the list management code
into get/put routines.
Signed-off-by: Alex Elder <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index e259fee..e7727e8 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2154,26 +2154,36 @@
static atomic64_t rbd_id_max = ATOMIC64_INIT(0);
/*
- * Get a unique rbd identifier. The minimum rbd id is 1.
+ * Get a unique rbd identifier for the given new rbd_dev, and add
+ * the rbd_dev to the global list. The minimum rbd id is 1.
*/
-static int rbd_id_get(void)
+static void rbd_id_get(struct rbd_device *rbd_dev)
{
- return atomic64_inc_return(&rbd_id_max);
+ rbd_dev->id = atomic64_inc_return(&rbd_id_max);
+
+ spin_lock(&rbd_dev_list_lock);
+ list_add_tail(&rbd_dev->node, &rbd_dev_list);
+ spin_unlock(&rbd_dev_list_lock);
}
/*
- * Record that an rbd identifier is no longer in use.
+ * Remove an rbd_dev from the global list, and record that its
+ * identifier is no longer in use.
*/
-static void rbd_id_put(int rbd_id)
+static void rbd_id_put(struct rbd_device *rbd_dev)
{
- BUG_ON(rbd_id < 1);
+ BUG_ON(rbd_dev->id < 1);
+
+ spin_lock(&rbd_dev_list_lock);
+ list_del_init(&rbd_dev->node);
+ spin_unlock(&rbd_dev_list_lock);
/*
* New id's are always one more than the current maximum.
* If the id being "put" *is* that maximum, decrement the
* maximum so the next one requested just reuses this one.
*/
- atomic64_cmpxchg(&rbd_id_max, rbd_id, rbd_id - 1);
+ atomic64_cmpxchg(&rbd_id_max, rbd_dev->id, rbd_dev->id - 1);
}
static ssize_t rbd_add(struct bus_type *bus,
@@ -2211,12 +2221,7 @@
init_rwsem(&rbd_dev->header.snap_rwsem);
/* generate unique id: one more than highest used so far */
- rbd_dev->id = rbd_id_get();
-
- /* add to global list */
- spin_lock(&rbd_dev_list_lock);
- list_add_tail(&rbd_dev->node, &rbd_dev_list);
- spin_unlock(&rbd_dev_list_lock);
+ rbd_id_get(rbd_dev);
/* parse add command */
if (sscanf(buf, "%" __stringify(RBD_MAX_OPT_LEN) "s "
@@ -2279,10 +2284,7 @@
return count;
err_out_bus:
- spin_lock(&rbd_dev_list_lock);
- list_del_init(&rbd_dev->node);
- spin_unlock(&rbd_dev_list_lock);
- rbd_id_put(target_id);
+ rbd_id_put(rbd_dev);
/* this will also clean up rest of rbd_dev stuff */
@@ -2296,10 +2298,7 @@
err_out_client:
rbd_put_client(rbd_dev);
err_out_slot:
- spin_lock(&rbd_dev_list_lock);
- list_del_init(&rbd_dev->node);
- spin_unlock(&rbd_dev_list_lock);
- rbd_id_put(target_id);
+ rbd_id_put(rbd_dev);
kfree(rbd_dev);
err_out_opt:
@@ -2380,11 +2379,7 @@
goto done;
}
- spin_lock(&rbd_dev_list_lock);
- list_del_init(&rbd_dev->node);
- spin_unlock(&rbd_dev_list_lock);
-
- rbd_id_put(target_id);
+ rbd_id_put(rbd_dev);
__rbd_remove_all_snaps(rbd_dev);
rbd_bus_del_dev(rbd_dev);