Cancel the watchdog before deactivating SMAPIv1 VDI

Previously the tapdisk watchdog in SMAPIv1 mirroring was cancelled in
the `post_deactivate_hook`, but at that point the VDI has already been
deactivated, and hence the mirror would have been terminated.
Additionally, the last time the stats is retrieved is in
`pre_deactivate_hook`, so do this cancelling after the last stats
retrival.

Note that SMAPIv3 mirror does not have a watchdog due to the limitations
of the mirror job auto cancel after guest pause, so instead the mirror
checking is only done whilst the mirror syncing (i.e. copying existing
disk content) is in progress.

Signed-off-by: Vincent Liu <[email protected]>

Author: Vincent-lau

ocaml/xapi/storage_migrate.ml

@@ -331,8 +331,7 @@ let post_deactivate_hook ~sr ~vdi ~dp:_ =
          ) ;
          debug "Finished calling receive_finalize2" ;
          State.remove_local_mirror id ;
-         debug "Removed active local mirror: %s" id ;
-         Option.iter (fun id -> Scheduler.cancel scheduler id) r.watchdog
+         debug "Removed active local mirror: %s" id
      )
 
 let nbd_handler req s ?(vm = "0") sr vdi dp =

ocaml/xapi/storage_smapiv1_migrate.ml

@@ -801,7 +801,10 @@ module MIRROR : SMAPIv2_MIRROR = struct
                  if st.Stats.nbd_mirror_failed = 1 then (
                    D.error "tapdisk reports mirroring failed" ;
                    s.failed <- true
-                 )
+                 ) ;
+                 Option.iter
+                   (fun id -> Scheduler.cancel scheduler id)
+                   s.watchdog
            with
            | Timeout elapsed ->
                D.error