Implement send_start for SMAPIv1

Now that the split is done, we can implement the `send_start` function
defined earlier for SMAPIv1, by combining all the different stages into
one function and invoke it from `Storage_migrate.start`.

At this point the refacotring for SMAPIv1 should be finished, and there
should still be no functional change.

Signed-off-by: Vincent Liu <shuntian.liu2@cloud.com>

Author: incipit0

ocaml/xapi/storage_migrate.ml

@@ -298,32 +298,15 @@ module MigrateLocal = struct
     State.add mirror_id (State.Send_op alm) ;
     debug "%s Added mirror %s to active local mirrors" __FUNCTION__ mirror_id ;
     (* A list of cleanup actions to perform if the operation should fail. *)
+    let (module Migrate_Backend) = choose_backend dbg sr in
     try
-      let (Vhd_mirror remote_mirror) =
+      let remote_mirror =
         prepare ~dbg ~sr ~vdi ~dest ~local_vdi ~mirror_id ~mirror_vm ~url
           ~verify_dest
       in
-      let tapdev =
-        Storage_smapiv1_migrate.mirror_pass_fds ~dbg ~dp ~sr ~vdi ~mirror_vm
-          ~mirror_id ~url ~dest_sr:dest ~verify_dest ~remote_mirror
-      in
-      let snapshot =
-        Storage_smapiv1_migrate.mirror_snapshot ~dbg ~sr ~dp ~mirror_id
-          ~local_vdi
-      in
-      Storage_smapiv1_migrate.mirror_checker mirror_id tapdev ;
-      let new_parent =
-        Storage_smapiv1_migrate.mirror_copy ~task ~dbg ~sr ~snapshot ~copy_vm
-          ~url ~dest_sr:dest ~remote_mirror ~verify_dest
-      in
-      debug "Local VDI %s = remote VDI %s"
-        (Storage_interface.Vdi.string_of snapshot.vdi)
-        (Storage_interface.Vdi.string_of new_parent.vdi) ;
-      debug "Local VDI %s now mirrored to remote VDI: %s"
-        (Storage_interface.Vdi.string_of local_vdi.vdi)
-        (Storage_interface.Vdi.string_of remote_mirror.Mirror.mirror_vdi.vdi) ;
-      debug "Destroying snapshot on src" ;
-      Local.VDI.destroy dbg sr snapshot.vdi ;
+      Migrate_Backend.send_start () ~dbg ~task_id:task ~dp ~sr ~vdi ~mirror_vm
+        ~mirror_id ~local_vdi ~copy_vm ~live_vm:(Vm.of_string "0") ~url
+        ~remote_mirror ~dest_sr:dest ~verify_dest ;
       Some (Mirror_id mirror_id)
     with
     | Storage_error (Sr_not_attached sr_uuid) ->
@@ -628,8 +611,10 @@ let copy ~dbg ~sr ~vdi ~vm ~url ~dest ~verify_dest =
 let start ~dbg ~sr ~vdi ~dp ~mirror_vm ~copy_vm ~url ~dest ~verify_dest =
   with_dbg ~name:__FUNCTION__ ~dbg @@ fun dbg ->
   with_task_and_thread ~dbg (fun task ->
-      MigrateLocal.start ~task ~dbg:dbg.Debug_info.log ~sr ~vdi ~dp ~mirror_vm
-        ~copy_vm ~url ~dest ~verify_dest
+      MigrateLocal.start
+        ~task:(Storage_task.id_of_handle task)
+        ~dbg:dbg.Debug_info.log ~sr ~vdi ~dp ~mirror_vm ~copy_vm ~url ~dest
+        ~verify_dest
   )
 
 (* XXX: PR-1255: copy the xenopsd 'raise Exception' pattern *)

ocaml/xapi/storage_smapiv1_migrate.ml

@@ -556,12 +556,41 @@ let mirror_copy ~task ~dbg ~sr ~snapshot ~copy_vm ~url ~dest_sr ~remote_mirror
   with e ->
     raise (Storage_error (Migration_mirror_copy_failure (Printexc.to_string e)))
 
+let mirror_cleanup ~dbg ~sr ~snapshot =
+  D.debug "Destroying snapshot on src" ;
+  Local.VDI.destroy dbg sr snapshot.vdi
+
 module MIRROR : SMAPIv2_MIRROR = struct
   type context = unit
 
-  let u x = raise Storage_interface.(Storage_error (Errors.Unimplemented x))
+  let send_start _ctx ~dbg ~task_id ~dp ~sr ~vdi ~mirror_vm ~mirror_id
+      ~local_vdi ~copy_vm ~live_vm:_ ~url ~remote_mirror ~dest_sr ~verify_dest =
+    let (module Remote) =
+      Storage_migrate_helper.get_remote_backend url verify_dest
+    in
+    match remote_mirror with
+    | Mirror.Vhd_mirror mirror_res ->
+        let tapdev =
+          mirror_pass_fds ~dbg ~dp ~sr ~vdi ~mirror_vm ~mirror_id ~url ~dest_sr
+            ~verify_dest ~remote_mirror:mirror_res
+        in
+
+        let snapshot = mirror_snapshot ~dbg ~sr ~dp ~mirror_id ~local_vdi in
+
+        mirror_checker mirror_id tapdev ;
+        let task = Storage_task.(handle_of_id tasks) task_id in
+        let new_parent =
+          mirror_copy ~task ~dbg ~sr ~snapshot ~copy_vm ~url ~dest_sr
+            ~remote_mirror:mirror_res ~verify_dest
+        in
 
-  let send_start _ctx = u __FUNCTION__
+        D.debug "Local VDI %s = remote VDI %s"
+          (Storage_interface.Vdi.string_of snapshot.vdi)
+          (Storage_interface.Vdi.string_of new_parent.vdi) ;
+        D.debug "Local VDI %s now mirrored to remote VDI: %s"
+          (Storage_interface.Vdi.string_of local_vdi.vdi)
+          (Storage_interface.Vdi.string_of mirror_res.Mirror.mirror_vdi.vdi) ;
+        mirror_cleanup ~dbg ~sr ~snapshot
 
   let receive_start_common ~dbg ~sr ~vdi_info ~id ~similar ~vm =
     let on_fail : (unit -> unit) list ref = ref [] in