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.

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

1 files changed, 8 insertions, 12 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 3802a7857280..a3a11c3c1cac 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -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_client *osdc;
@@ -1210,9 +1209,9 @@ 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);