rbd: assign watch request more directly

Both rbd_req_sync_op() and rbd_do_request() have a "linger" parameter, which is the address of a pointer that should refer to the osd request structure used to issue a request to an osd.

Only one case ever supplies a non-null "linger" argument: an CEPH_OSD_OP_WATCH start. And in that one case it is assigned &rbd_dev->watch_request.

Within rbd_do_request() (where the assignment ultimately gets made) we know the rbd_dev and therefore its watch_request field. We also know whether the op being sent is CEPH_OSD_OP_WATCH start.

Stop opaquely passing down the "linger" pointer, and instead just assign the value directly inside rbd_do_request() when it's needed.

This makes it unnecessary for rbd_req_sync_watch() to make arrangements to hold a value that's not available until a bit later. This more clearly separates setting up a watch request from submitting it.

---
 drivers/block/rbd.c |   20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

index 0647637..acdb4a6 100644
@@ -1158,7 +1158,6 @@ static int rbd_do_request(struct request *rq,
 			  int coll_index,
 			  void (*rbd_cb)(struct ceph_osd_request *,
 					 struct ceph_msg *),
-			  struct ceph_osd_request **linger_req,
 			  u64 *ver)
 {
 	struct ceph_osd_request *osd_req;

@@ -1212,9 +1211,9 @@ static int rbd_do_request(struct request *rq,
 	ceph_osdc_build_request(osd_req, ofs, len, 1, op,
 				snapc, snapid, &mtime);
 
-	if (linger_req) {
+	if (op->op == CEPH_OSD_OP_WATCH && op->watch.flag) {
 		ceph_osdc_set_request_linger(osdc, osd_req);
-		*linger_req = osd_req;
+		rbd_dev->watch_request = osd_req;
 	}
 
 	ret = ceph_osdc_start_request(osdc, osd_req, false);

@@ -1296,7 +1295,6 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
 			   const char *object_name,
 			   u64 ofs, u64 inbound_size,
 			   char *inbound,
-			   struct ceph_osd_request **linger_req,
 			   u64 *ver)
 {
 	int ret;

@@ -1317,7 +1315,7 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
 			  op,
 			  NULL, 0,
 			  NULL,
-			  linger_req, ver);
+			  ver);
 	if (ret < 0)
 		goto done;
 

@@ -1383,7 +1381,7 @@ static int rbd_do_op(struct request *rq,
 			     flags,
 			     op,
 			     coll, coll_index,
-			     rbd_req_cb, 0, NULL);
+			     rbd_req_cb, NULL);
 	if (ret < 0)
 		rbd_coll_end_req_index(rq, coll, coll_index,
 					(s32) ret, seg_len);

@@ -1410,7 +1408,7 @@ static int rbd_req_sync_read(struct rbd_device

*rbd_dev,
return -ENOMEM;

ret = rbd_req_sync_op(rbd_dev, CEPH_OSD_FLAG_READ,
- op, object_name, ofs, len, buf, NULL, ver);
+ op, object_name, ofs, len, buf, ver);
rbd_osd_req_op_destroy(op);

return ret;
@@ -1436,7 +1434,7 @@ static int rbd_req_sync_notify_ack(struct rbd_device *rbd_dev,
CEPH_OSD_FLAG_READ,
op,
NULL, 0,
- rbd_simple_req_cb, 0, NULL);
+ rbd_simple_req_cb, NULL);

rbd_osd_req_op_destroy(op);

@@ -1469,7 +1467,6 @@ 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_request **linger_req = NULL;
struct ceph_osd_req_op *op;
int ret = 0;

@@ -1481,7 +1478,6 @@ static int rbd_req_sync_watch(struct rbd_device *rbd_dev, int start)
&rbd_dev->watch_event);
if (ret < 0)
return ret;
- linger_req = &rbd_dev->watch_request;
} else {
rbd_assert(rbd_dev->watch_request != NULL);
}
@@ -1493,7 +1489,7 @@ static int rbd_req_sync_watch(struct rbd_device *rbd_dev, int start)
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);
+ 0, 0, NULL, NULL);

/* Cancel the event if we're tearing down, or on error */

@@ -1537,7 +1533,7 @@ static int rbd_req_sync_exec(struct rbd_device *rbd_dev,

ret = rbd_req_sync_op(rbd_dev, CEPH_OSD_FLAG_READ, op,
object_name, 0, inbound_size, inbound,
- NULL, ver);
+ ver);

rbd_osd_req_op_destroy(op);

1.7.9.5