Merge pull request #142 from djs55/xenvm-offline

Add an `--offline` mode for `xenvm lvs`

Author: djs55

xenvm/lvchange.ml

@@ -170,15 +170,11 @@ let del_tag_arg =
   let doc = "Remove the given tag from the LV" in
   Arg.(value & opt (some string) None & info ["deltag"] ~docv:"DELTAG" ~doc)
 
-let offline_arg =
-  let doc = "Assume xenvmd is offline and read metadata from the disk" in
-  Arg.(value & flag & info [ "offline" ] ~docv:"OFFLINE" ~doc)
- 
 let lvchange_cmd =
   let doc = "Change the attributes of a logical volume" in
   let man = [
     `S "DESCRIPTION";
     `P "lvchange allows you to change the attributes of a logical volume including making them known to the kernel ready for use."
   ] in
-  Term.(pure lvchange $ Xenvm_common.copts_t $ Xenvm_common.name_arg $ Xenvm_common.physical_device_arg $ action_arg $ perm_arg $ refresh_arg $ add_tag_arg $ del_tag_arg $ offline_arg),
+  Term.(pure lvchange $ Xenvm_common.copts_t $ Xenvm_common.name_arg $ Xenvm_common.physical_device_arg $ action_arg $ perm_arg $ refresh_arg $ add_tag_arg $ del_tag_arg $ Xenvm_common.offline_arg),
   Term.info "lvchange" ~sdocs:"COMMON OPTIONS" ~doc ~man

xenvm/lvs.ml

@@ -3,6 +3,7 @@
 open Cmdliner
 open Xenvm_common
 open Lwt
+open Errors
 
 let default_fields = [
  "lv_name";
@@ -18,7 +19,7 @@ let default_fields = [
  "convert_lv"]
 
 
-let lvs copts noheadings nosuffix units fields (vg_name,lv_name_opt) =
+let lvs copts noheadings nosuffix units fields offline physical_device (vg_name,lv_name_opt) =
   let open Xenvm_common in
   let segs = has_seg_field fields in
   let do_row dev vg lv =
@@ -36,10 +37,22 @@ let lvs copts noheadings nosuffix units fields (vg_name,lv_name_opt) =
   Lwt_main.run (
     get_vg_info_t copts vg_name >>= fun info ->
     set_uri copts info;
-    let dev = match info with | Some i -> i.local_device | None -> "<unknown>" in
+    let dev : string = match (info,physical_device) with
+      | _, Some d -> d (* cmdline overrides default for the VG *)
+      | Some info, None -> info.local_device (* If we've got a default, use that *)
+      | None, None -> failwith "Need to know the local device!" in
+
     Lwt.catch
-      (Client.get)
-      (fun _ ->
+      (fun () ->
+        if offline then begin
+          with_block dev
+            (fun x ->
+              let module Vg_IO = Lvm.Vg.Make(Log)(Block)(Time)(Clock) in
+              Vg_IO.connect [ x ] `RO >>|= fun vg ->
+              return (Vg_IO.metadata_of vg)
+            )
+        end else Client.get ()
+      ) (fun _ ->
         stderr "  Volume group \"%s\" not found" vg_name
         >>= fun () ->
         stderr "  Skipping volume group %s" vg_name
@@ -66,5 +79,5 @@ let lvs_cmd =
     `S "DESCRIPTION";
     `P "lvs produces formatted output about logical volumes";
   ] in
-  Term.(pure lvs $ Xenvm_common.copts_t $ noheadings_arg $ nosuffix_arg $ units_arg $ output_arg default_fields $ Xenvm_common.name_arg),
+  Term.(pure lvs $ Xenvm_common.copts_t $ noheadings_arg $ nosuffix_arg $ units_arg $ output_arg default_fields $ Xenvm_common.offline_arg $ Xenvm_common.physical_device_arg $ Xenvm_common.name_arg),
   Term.info "lvs" ~sdocs:"COMMON OPTIONS" ~doc ~man

xenvm/xenvm_common.ml

@@ -493,3 +493,8 @@ let action_arg =
 Activation  of a logical volume creates a symbolic link /dev/VolumeGroupName/LogicalVolumeName pointing to the device node.  This link is removed on deactivation.  All software and scripts should access the device through this symbolic link and present this as the name of the device.  The location and name of the underlying device node may depend on the  distribution and configuration (e.g. udev) and might change from release to release." in
   let a = Arg.(value & opt (some char) None & info ["a"] ~docv:"ACTIVATE" ~doc) in
   Term.(pure parse_action $ a)
+
+let offline_arg =
+  let doc = "Assume xenvmd is offline and read metadata from the disk"
+  in
+  Arg.(value & flag & info [ "offline" ] ~docv:"OFFLINE" ~doc)