rbd: send header version when notifying

Previously the original header version was sent. Now, we update it
when the header changes.
Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com>
Reviewed-by: Alex Elder <elder@inktank.com>
(cherry picked from commit a71b891b)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/block/rbd.c

@@ -1195,7 +1195,7 @@ static int rbd_req_sync_notify_ack(struct rbd_device *dev,
 	if (ret < 0)
 		return ret;
 
-	ops[0].watch.ver = cpu_to_le64(dev->header.obj_version);
+	ops[0].watch.ver = cpu_to_le64(ver);
 	ops[0].watch.cookie = notify_id;
 	ops[0].watch.flag = 0;
 
@@ -1215,6 +1215,7 @@ static int rbd_req_sync_notify_ack(struct rbd_device *dev,
 static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
 {
 	struct rbd_device *dev = (struct rbd_device *)data;
+	u64 hver;
 	int rc;
 
 	if (!dev)
@@ -1224,12 +1225,13 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
 		notify_id, (int)opcode);
 	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
 	rc = __rbd_update_snaps(dev);
+	hver = dev->header.obj_version;
 	mutex_unlock(&ctl_mutex);
 	if (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);
+	rbd_req_sync_notify_ack(dev, hver, notify_id, dev->obj_md_name);
 }
 
 /*
@@ -1740,6 +1742,7 @@ static int __rbd_update_snaps(struct rbd_device *rbd_dev)
 	kfree(rbd_dev->header.snap_names);
 	kfree(rbd_dev->header.snap_sizes);
 
+	rbd_dev->header.obj_version = h.obj_version;
 	rbd_dev->header.image_size = h.image_size;
 	rbd_dev->header.total_snaps = h.total_snaps;
 	rbd_dev->header.snapc = h.snapc;