Merge pull request #135 from simonjbeaumont/force-disconnect

Add uncooperative disconnect

Author: Jon Ludlam

cleanup.sh

@@ -22,4 +22,4 @@ if [ "$USE_MOCK" -eq "0" ]; then
   losetup -d $LOOP
 fi
 
-rm -f localJournal bigdisk *.out*  djstest-* dm-mock
+rm -f localJournal bigdisk *.out*  djstest-* dm-mock xenvmd.log*

idl/xenvm_interface.ml

@@ -69,7 +69,7 @@ module Host = struct
   (** [connect host] connects to existing metadata volumes and
       process them. *)
 
-  external disconnect: name:string -> unit = ""
+  external disconnect: cooperative:bool -> name:string -> unit = ""
   (** [disconnect host] disconnects from metadata volumes and
       stops processing them. *)
 

setup.sh

@@ -76,9 +76,21 @@ kill `cat /tmp/xenvmd.lock`
 sleep 10
 ./xenvm.native host-list /dev/djstest --configdir /tmp/xenvm.d $MOCK_ARG | sort > host-list.out2
 diff -u host-list.out host-list.out2 
-  
+
+# simulate a host failure and uncooperative disconnect
+kill `cat /tmp/host2-socket.lock`
+./xenvm.native host-disconnect --uncooperative /dev/djstest host2 --configdir /tmp/xenvm.d $MOCK_ARG
+# check we've lost a host in the host-list
+./xenvm.native host-list /dev/djstest --configdir /tmp/xenvm.d $MOCK_ARG | sort > host-list.out3
+grep -v host2 host-list.out2 | diff -u - host-list.out3
+# check it doesn't reconnect after a restart
+kill `cat /tmp/xenvmd.lock`
+./xenvmd.native --config ./test.xenvmd.conf > xenvmd.log.3 &
+sleep 10
+./xenvm.native host-list /dev/djstest --configdir /tmp/xenvm.d $MOCK_ARG | sort > host-list.out4
+diff -u host-list.out3 host-list.out4
+
 # destroy hosts
-./xenvm.native host-disconnect /dev/djstest host2 --configdir /tmp/xenvm.d $MOCK_ARG
 ./xenvm.native host-destroy /dev/djstest host2 --configdir /tmp/xenvm.d $MOCK_ARG
 ./xenvm.native host-disconnect /dev/djstest host1 --configdir /tmp/xenvm.d $MOCK_ARG
 ./xenvm.native host-destroy /dev/djstest host1 --configdir /tmp/xenvm.d $MOCK_ARG

xenvm/xenvm.ml

@@ -91,11 +91,11 @@ let host_connect copts (vg_name,_) host =
     set_uri copts info;
     Client.Host.connect host in
   Lwt_main.run t
-let host_disconnect copts (vg_name,_) host =
+let host_disconnect copts (vg_name,_) uncooperative host =
   let t =
     get_vg_info_t copts vg_name >>= fun info ->
     set_uri copts info;
-    Client.Host.disconnect host in
+    Client.Host.disconnect ~cooperative:(not uncooperative) ~name:host in
   Lwt_main.run t 
 let host_destroy copts (vg_name,_) host =
   let t =
@@ -232,12 +232,15 @@ let host_connect_cmd =
   Term.info "host-connect" ~sdocs:copts_sect ~doc ~man
 
 let host_disconnect_cmd =
-  let doc = "Disconnect to a host" in
+  let uncooperative_flag =
+    let doc = "Perform an uncooperative disconnect (if the host is dead)" in
+    Arg.(value & flag & info ["uncooperative"] ~doc) in
+  let doc = "Disconnect from a host" in
   let man = [
     `S "DESCRIPTION";
-    `P "Dergister a host with the daemon. The daemon will suspend the block queues and stop listening to requests.";
+    `P "Dergister a host with the daemon. The daemon will suspend the block queues (unless the --uncooperative flag is used) and stop listening to requests.";
   ] in
-  Term.(pure host_disconnect $ copts_t $ name_arg $ hostname),
+  Term.(pure host_disconnect $ copts_t $ name_arg $ uncooperative_flag $ hostname),
   Term.info "host-disconnect" ~sdocs:copts_sect ~doc ~man
 
 let host_create_cmd =

xenvm/xenvm_common.ml

@@ -249,8 +249,9 @@ let physical_device_arg_required =
 let parse_name name_arg =
   let comps = Stringext.split name_arg '/' in
   match comps with
-  | ["";"dev";vg;lv] -> (vg,Some lv)
+  | ["";"dev";vg;""]
   | ["";"dev";vg] -> (vg,None)
+  | ["";"dev";vg;lv] -> (vg,Some lv)
   | [vg;lv] -> (vg,Some lv)
   | [vg] -> (vg,None)
   | _ -> failwith "failed to parse vg name"

xenvmd/xenvmd.ml

@@ -393,18 +393,20 @@ module VolumeManager = struct
         ToLVM.advance to_lvm pos
       end
 
-    let disconnect name =
+    let disconnect ~cooperative name =
       if Hashtbl.mem host_connections name then begin
         match Hashtbl.find host_connections name with
         | Xenvm_interface.Connected ->
           let to_lvm = List.assoc name !to_LVMs in
-          debug "Suspending ToLVM queue for %s" name;
-          ToLVM.suspend to_lvm
-          >>= fun () -> 
+          ( if cooperative then begin
+              debug "Cooperative disconnect: suspending ToLVM queue for %s" name;
+              ToLVM.suspend to_lvm
+            end else return ()
+          ) >>= fun () ->
           (* There may still be updates in the ToLVM queue *)
+          debug "Flushing ToLVM queue for %s" name;
           Lwt_mutex.with_lock flush_m (fun () -> flush_already_locked name)
           >>= fun () ->
-          debug "ToLVM queue for %s has been suspended and flushed" name;
           to_LVMs := List.filter (fun (n, _) -> n <> name) !to_LVMs;
           from_LVMs := List.filter (fun (n, _) -> n <> name) !from_LVMs;
           free_LVs := List.filter (fun (n, _) -> n <> name) !free_LVs;
@@ -419,7 +421,7 @@ module VolumeManager = struct
       end else return ()
 
     let destroy name =
-      disconnect name
+      disconnect ~cooperative:false name
       >>= fun () ->
       let toLVM = toLVM name in
       let fromLVM = fromLVM name in
@@ -487,7 +489,7 @@ module VolumeManager = struct
             vg.Lvm.Vg.lvs [] |> Lwt.return
         ) >>= fun host_states ->
       Lwt_list.iter_s (fun (host, was_connected) ->
-          if was_connected then connect host else disconnect host) host_states
+          if was_connected then connect host else disconnect ~cooperative:false host) host_states
 
   end
 
@@ -503,7 +505,7 @@ module VolumeManager = struct
   let shutdown () =
     Lwt_list.iter_s
       (fun (host, _) ->
-        Host.disconnect host
+        Host.disconnect ~cooperative:true host
       ) !from_LVMs
     >>= fun () ->
     sync ()
@@ -740,7 +742,7 @@ module Impl = struct
   module Host = struct
     let create context ~name = VolumeManager.Host.create name
     let connect context ~name = VolumeManager.Host.connect name
-    let disconnect context ~name = VolumeManager.Host.disconnect name
+    let disconnect context ~cooperative ~name = VolumeManager.Host.disconnect ~cooperative name
     let destroy context ~name = VolumeManager.Host.destroy name
     let all context () = VolumeManager.Host.all ()
   end