rbd: move remaining osd op setup into rbd_osd_req_op_create()

The two remaining osd ops used by rbd are CEPH_OSD_OP_WATCH and
CEPH_OSD_OP_NOTIFY_ACK.  Move the setup of those operations into
rbd_osd_req_op_create(), and get rid of rbd_create_rw_op() and
rbd_destroy_op().

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -1027,24 +1027,6 @@ static struct bio *bio_chain_clone_range(struct bio **bio_src,
 	return NULL;
 }
 
-static struct ceph_osd_req_op *rbd_create_rw_op(int opcode, u64 ofs, u64 len)
-{
-	struct ceph_osd_req_op *op;
-
-	op = kzalloc(sizeof (*op), GFP_NOIO);
-	if (!op)
-		return NULL;
-
-	op->op = opcode;
-
-	return op;
-}
-
-static void rbd_destroy_op(struct ceph_osd_req_op *op)
-{
-	kfree(op);
-}
-
 struct ceph_osd_req_op *rbd_osd_req_op_create(u16 opcode, ...)
 {
 	struct ceph_osd_req_op *op;
@@ -1087,6 +1069,16 @@ struct ceph_osd_req_op *rbd_osd_req_op_create(u16 opcode, ...)
 		op->cls.indata_len = (u32) size;
 		op->payload_len += size;
 		break;
+	case CEPH_OSD_OP_NOTIFY_ACK:
+	case CEPH_OSD_OP_WATCH:
+		/* rbd_osd_req_op_create(NOTIFY_ACK, cookie, version) */
+		/* rbd_osd_req_op_create(WATCH, cookie, version, flag) */
+		op->watch.cookie = va_arg(args, u64);
+		op->watch.ver = va_arg(args, u64);
+		op->watch.ver = cpu_to_le64(op->watch.ver);
+		if (opcode == CEPH_OSD_OP_WATCH && va_arg(args, int))
+			op->watch.flag = (u8) 1;
+		break;
 	default:
 		rbd_warn(NULL, "unsupported opcode %hu\n", opcode);
 		kfree(op);
@@ -1434,14 +1426,10 @@ static int rbd_req_sync_notify_ack(struct rbd_device *rbd_dev,
 	struct ceph_osd_req_op *op;
 	int ret;
 
-	op = rbd_create_rw_op(CEPH_OSD_OP_NOTIFY_ACK, 0, 0);
+	op = rbd_osd_req_op_create(CEPH_OSD_OP_NOTIFY_ACK, notify_id, ver);
 	if (!op)
 		return -ENOMEM;
 
-	op->watch.ver = cpu_to_le64(ver);
-	op->watch.cookie = notify_id;
-	op->watch.flag = 0;
-
 	ret = rbd_do_request(NULL, rbd_dev, NULL, CEPH_NOSNAP,
 			  rbd_dev->header_name, 0, 0, NULL,
 			  NULL, 0,
@@ -1450,7 +1438,8 @@ static int rbd_req_sync_notify_ack(struct rbd_device *rbd_dev,
 			  NULL, 0,
 			  rbd_simple_req_cb, 0, NULL);
 
-	rbd_destroy_op(op);
+	rbd_osd_req_op_destroy(op);
+
 	return ret;
 }
 
@@ -1480,14 +1469,9 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
  */
 static int rbd_req_sync_watch(struct rbd_device *rbd_dev, int start)
 {
-	struct ceph_osd_req_op *op;
 	struct ceph_osd_request **linger_req = NULL;
-	__le64 version = 0;
-	int ret;
-
-	op = rbd_create_rw_op(CEPH_OSD_OP_WATCH, 0, 0);
-	if (!op)
-		return -ENOMEM;
+	struct ceph_osd_req_op *op;
+	int ret = 0;
 
 	if (start) {
 		struct ceph_osd_client *osdc;
@@ -1496,26 +1480,28 @@ static int rbd_req_sync_watch(struct rbd_device *rbd_dev, int start)
 		ret = ceph_osdc_create_event(osdc, rbd_watch_cb, 0, rbd_dev,
 						&rbd_dev->watch_event);
 		if (ret < 0)
-			goto done;
-		version = cpu_to_le64(rbd_dev->header.obj_version);
+			return ret;
 		linger_req = &rbd_dev->watch_request;
+	} else {
+		rbd_assert(rbd_dev->watch_request != NULL);
 	}
 
-	op->watch.ver = version;
-	op->watch.cookie = cpu_to_le64(rbd_dev->watch_event->cookie);
-	op->watch.flag = (u8) start ? 1 : 0;
-
-	ret = rbd_req_sync_op(rbd_dev,
+	op = rbd_osd_req_op_create(CEPH_OSD_OP_WATCH,
+				rbd_dev->watch_event->cookie,
+				rbd_dev->header.obj_version, start);
+	if (op)
+		ret = rbd_req_sync_op(rbd_dev,
 			      CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
 			      op, rbd_dev->header_name,
 			      0, 0, NULL, linger_req, NULL);
 
-	if (!start || ret < 0) {
+	/* Cancel the event if we're tearing down, or on error */
+
+	if (!start || !op || ret < 0) {
 		ceph_osdc_cancel_event(rbd_dev->watch_event);
 		rbd_dev->watch_event = NULL;
 	}
-done:
-	rbd_destroy_op(op);
+	rbd_osd_req_op_destroy(op);
 
 	return ret;
 }