Merge pull request #117 from xapi-project/safety-label

Refuse to open a device if it has the wrong label

Author: djs55

test/test.ml

@@ -47,9 +47,29 @@ let vgs_offline =
     )
   )
 
+let pvremove =
+  "pvremove <device>: check that we can make a PV unrecognisable" >::
+  (fun () ->
+    with_temp_file (fun filename ->
+      xenvm [ "vgcreate"; vg; filename ] |> ignore_string;
+      mkdir_rec "/tmp/xenvm.d" 0o0755;
+      xenvm [ "set-vg-info"; "--pvpath"; filename; "-S"; "/tmp/xenvmd"; vg; "--local-allocator-path"; "/tmp/xenvm-local-allocator"; "--uri"; "file://local/services/xenvmd/"^vg ] |> ignore_string;
+      xenvm [ "vgs"; vg ] |> ignore_string;
+      xenvm [ "pvremove"; filename ] |> ignore_string;
+      begin
+        try
+          xenvm [ "vgs"; vg ] |> ignore_string;
+          failwith "pvremove failed to hide a VG from vgs"
+        with Bad_exit(1, _, _, _, _) ->
+          ()
+      end
+    )
+  )
+
 let no_xenvmd_suite = "Commands which should work without xenvmd" >::: [
   vgcreate;
   vgs_offline;
+  pvremove;
 ]
 
 let assert_lv_exists ?expected_size_in_extents name =

xenvm/pvremove.ml

@@ -7,20 +7,6 @@ open Lwt
 open Lvm
 module Pv_IO = Pv.Make(Block)
 
-let (>>*=) m f = match m with
-  | `Error (`Msg e) -> fail (Failure e)
-  | `Ok x -> f x
-
-let (>>|=) m f = m >>= fun x -> x >>*= f
-
-let with_block filename f =
-  let open Lwt in
-  Block.connect filename
-  >>= function
-  | `Error _ -> fail (Failure (Printf.sprintf "Unable to read %s" filename))
-  | `Ok x ->
-    Lwt.catch (fun () -> f x) (fun e -> Block.disconnect x >>= fun () -> fail e)
-
 let pvremove copts undo filenames =
   let open Xenvm_common in
   Lwt_main.run (

xenvmd/xenvmd.ml

@@ -146,6 +146,26 @@ module VolumeManager = struct
         | `Ok x -> return x
       ) devices'
     >>= fun devices' ->
+    let module Label_IO = Lvm.Label.Make(Block) in
+    Lwt_list.iter_s
+      (fun device ->
+        Label_IO.read device >>= function
+        | `Error (`Msg m) ->
+          error "Failed to read PV label from device: %s" m;
+          fail (Failure "Failed to read PV label from device")
+        | `Ok label ->
+          begin match Lvm.Label.Label_header.magic_of label.Lvm.Label.label_header with
+          | Some `Lvm ->
+            error "Device has normal LVM PV label. I will only open devices with the new PV label.";
+            fail (Failure "Device has wrong LVM PV label")
+          | Some `Journalled ->
+            return ()
+          | _ ->
+            error "Device has an unrecognised LVM PV label. I will only open devices with the new PV label.";
+            fail (Failure "Device has wrong PV label")
+          end
+      ) devices'
+    >>= fun () ->
     Vg_IO.connect ~flush_interval:5. devices' `RW >>|= fun vg ->
     Lwt.wakeup_later myvg_u vg;
     return ()