[Libguestfs] [PATCH 7/7] resize: Add workaround for qcow2 disk cache bug in qemu (RHBZ#836710).
From: "Richard W.M. Jones" <rjones(a)redhat.com>
Best to read the comment.
---
resize/Makefile.am | 2 +-
resize/resize.ml | 33 ++++++++++++++++++++++++++++++++-
2 files changed, 33 insertions(+), 2 deletions(-)
diff --git a/resize/Makefile.am b/resize/Makefile.am
index 70ace37..1234c96 100644
--- a/resize/Makefile.am
+++ b/resize/Makefile.am
@@ -56,7 +56,7 @@ bin_SCRIPTS = virt-resize
# -I $(top_builddir)/src/.libs is a hack which forces corresponding -L
# option to be passed to gcc, so we don't try linking against an
# installed copy of libguestfs.
-OCAMLPACKAGES = -package str -I $(top_builddir)/src/.libs -I ../ocaml
+OCAMLPACKAGES = -package str,unix -I $(top_builddir)/src/.libs -I ../ocaml
if HAVE_OCAML_PKG_GETTEXT
OCAMLPACKAGES += -package gettext-stub
endif
diff --git a/resize/resize.ml b/resize/resize.ml
index cd4c9d6..3118d74 100644
--- a/resize/resize.ml
+++ b/resize/resize.ml
@@ -1010,6 +1010,36 @@ let () =
(* Copy over the data. *)
let () =
+ (* Obviously when you've got a function called 'hack_for_...' you
+ * know it cannot be good.
+ *
+ * This works around a bug in qemu's qcow2 block driver. If there
+ * are I/Os in flight and you send SIGTERM to qemu, then qemu
+ * segfaults. This particularly happens when the output file is
+ * growing rapidly (because of the partition copies below) and we
+ * close the handle (which kills qemu).
+ *
+ * The ugly workaround is to monitor the disk file and wait until it
+ * stops growing before closing the handle.
+ *
+ * https://bugzilla.redhat.com/show_bug.cgi?id=836710
+ * https://bugzilla.redhat.com/show_bug.cgi?id=836913
+ *)
+ let hack_for_rhbz836710 g ?format outfile =
+ match format with
+ | None | Some "qcow2" -> (* only for qcow2 or auto *)
+ let get_size () = (Unix.LargeFile.stat outfile).Unix.LargeFile.st_size in
+ let rec loop size =
+ g#sync ();
+ g#sleep 1;
+ let size' = get_size () in
+ if size <> size' then
+ loop size'
+ in
+ loop (get_size ())
+ | _ -> ()
+ in
+
List.iter (
fun p ->
match p.p_operation with
@@ -1033,7 +1063,8 @@ let () =
(match p.p_type with
| ContentUnknown | ContentPV _ | ContentFS _ ->
- g#copy_device_to_device ~size:copysize source target
+ g#copy_device_to_device ~size:copysize source target;
+ hack_for_rhbz836710 g ?format:output_format outfile
| ContentExtendedPartition ->
(* You can't just copy an extended partition by name, eg.
--
1.7.10.4