rbd: make rbd_obj_notify_ack() synchronous

The only user of rbd_obj_notify_ack() is rbd_watch_cb(). It used
asynchronously with no tracking of when the notify ack completes, so
it may still be in progress when the osd_client is shut down.  This
results in a BUG() since the osd client assumes no requests are in
flight when it stops. Since all notifies are flushed before the
osd_client is stopped, waiting for the notify ack to complete before
returning from the watch callback ensures there are no notify acks in
flight during shutdown.

Rename rbd_obj_notify_ack() to rbd_obj_notify_ack_sync() to reflect
its new synchronous nature.

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

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index bf89e348d11b..9e5f07f936dd 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2808,7 +2808,7 @@ out_err:
         obj_request_done_set(obj_request);
 }
 
-static int rbd_obj_notify_ack(struct rbd_device *rbd_dev, u64 notify_id)
+static int rbd_obj_notify_ack_sync(struct rbd_device *rbd_dev, u64 notify_id)
 {
         struct rbd_obj_request *obj_request;
         struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
@@ -2823,16 +2823,17 @@ static int rbd_obj_notify_ack(struct rbd_device *rbd_dev, u64 notify_id)
         obj_request->osd_req = rbd_osd_req_create(rbd_dev, false, obj_request);
         if (!obj_request->osd_req)
                 goto out;
-        obj_request->callback = rbd_obj_request_put;
 
         osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_NOTIFY_ACK,
                                         notify_id, 0, 0);
         rbd_osd_req_format_read(obj_request);
 
         ret = rbd_obj_request_submit(osdc, obj_request);
-out:
         if (ret)
-                rbd_obj_request_put(obj_request);
+                goto out;
+        ret = rbd_obj_request_wait(obj_request);
+out:
+        rbd_obj_request_put(obj_request);
 
         return ret;
 }
@@ -2852,7 +2853,7 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
         if (ret)
                 rbd_warn(rbd_dev, "header refresh error (%d)\n", ret);
 
-        rbd_obj_notify_ack(rbd_dev, notify_id);
+        rbd_obj_notify_ack_sync(rbd_dev, notify_id);
 }
 
 /*