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Commit 499afd5b authored by Alex Elder's avatar Alex Elder
Browse files

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: default avatarAlex Elder <elder@dreamhost.com>
Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent e124a82f

drivers/block/rbd.c

+21 −26
Original line number Diff line number Diff line
@@ -2154,26 +2154,36 @@ static int rbd_init_watch_dev(struct rbd_device *rbd_dev) 
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 @@ static ssize_t rbd_add(struct bus_type *bus, 
	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 @@ static ssize_t rbd_add(struct bus_type *bus, 
	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 @@ static ssize_t rbd_add(struct bus_type *bus, 
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 @@ static ssize_t rbd_remove(struct bus_type *bus, 
		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);