CA-43021: Fix bug detecting the backing vhd file caused by reading the wrong device...

Signed-off-by: David Scott <dave.scott@eu.citrix.com>

diff --git a/ocaml/xapi/sparse_dd.ml b/ocaml/xapi/sparse_dd.ml
index 9903a49a6c71ed5a844b60a8f90f644e6146a85e..756c6262b53a7852da2a2bede6132f0a6417cdf0 100644 (file)
--- a/ocaml/xapi/sparse_dd.ml
+++ b/ocaml/xapi/sparse_dd.ml
@@ -353,18 +353,23 @@ let vhd_of_device path =
                        match Tapctl.of_device (Tapctl.create ()) path with
                        | _, _, (Some (_, vhd)) -> Some vhd
                        | _, _, _ -> raise Not_found
-               with Not_found -> None in
-       match tapdisk_of_path path with
-       | Some vhd -> Some vhd
-       | None ->
-               begin match find_underlying_tapdisk path with
-               | Some path ->
-                       begin match tapdisk_of_path path with
-                       | Some vhd -> Some vhd
-                       | None -> None
-                       end
+               with Tapctl.Not_blktap ->
+                       Printf.printf "Device %s is not controlled by blktap\n" path;
+                       None
+               | Tapctl.Not_a_device ->
+                       Printf.printf "%s is not a device\n" path;
+                       None
+               | _ -> 
+                       Printf.printf "Device %s has an unknown driver\n" path;
+                       None in
+       begin match find_underlying_tapdisk path with
+       | Some path ->
+               begin match tapdisk_of_path path with
+               | Some vhd -> Some vhd
                | None -> None
                end
+       | None -> None
+       end
 
 let deref_symlinks path = 
        let rec inner seen_already path = 
@@ -472,6 +477,7 @@ let _ =
        end;
        let empty = Bat.of_list [] in
 
+       Printf.printf "src = %s; dest = %s; base = %s; size = %Ld\n" (Opt.default "None" !src) (Opt.default "None" !dest) (Opt.default "None" !base) !size;
         let size = Some !size in
 
        (** [chain_of_device device] returns [None] if [device] is None.
@@ -484,7 +490,7 @@ let _ =
                let vhd : string option = flatten (Opt.map vhd_of_device device) in
                let chain : string list option = Opt.map chain_of_vhd vhd in
                let option y = Opt.default "None" (Opt.map (fun x -> "Some " ^ x) y) in
-               Printf.printf "%s has chain: [ %s ]" (option device) (option (Opt.map (String.concat "; ") chain));
+               Printf.printf "%s has chain: [ %s ]\n" (option device) (option (Opt.map (String.concat "; ") chain));
                chain in
 
        let bat : Bat.t option =