daemon: lvm_utils: Handle stat errors

lvm returns logical volumes even if they're broken, for instance when a
physical volume is missing in their volume group.
In such cases, stat would fail to resolve the provided path.
Handle such cases by skipping such failures when finding the matching
lvm device.

daemon/lvm_utils.ml

@@ -34,15 +34,26 @@ open Utils
  * resolved.
  *)
 let lv_canonical device =
-  let stat1 = stat device in
+  let stat1 =
+    try Some (stat device)
+    with Unix_error _ -> None in
+  match stat1 with
+  | None -> None
+  | Some stat1 ->
+  (
     let lvs = Lvm.lvs () in
     try
       Some (
         List.find (
           fun lv ->
-          let stat2 = stat lv in
-          stat1.st_rdev = stat2.st_rdev
+            let stat2 =
+              try Some (stat lv)
+              with Unix_error _ -> None in
+            match stat2 with
+            | Some stat2 -> stat1.st_rdev = stat2.st_rdev
+            | None -> false
         ) lvs
       )
     with
     | Not_found -> None
+  )