From 80831868395d161af8c47edf2f54234c63581d8d Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Fri, 28 Jan 2022 09:30:29 +0000

Subject: [PATCH] qemu-nbd: Implement output compression for qcow2 files

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

(cherry picked from commit 71c4301909cb307def02ebcd0e89beee4138e7f2)

---

 lib/qemuNBD.ml    | 11 +++++++++--

 lib/qemuNBD.mli   |  5 +++++

 output/output.ml  | 39 ++++++++++++++++++++++++++++++++++++---

 output/output.mli |  1 +

 4 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/lib/qemuNBD.ml b/lib/qemuNBD.ml

index ae21b17c..bbb65f41 100644

--- a/lib/qemuNBD.ml

+++ b/lib/qemuNBD.ml

@@ -55,14 +55,16 @@ type cmd = {

   disk : string;

   mutable snapshot : bool;

   mutable format : string option;

+  mutable imgopts : bool;

 }

-let create disk = { disk; snapshot = false; format = None }

+let create disk = { disk; snapshot = false; format = None; imgopts = false }

 let set_snapshot cmd snap = cmd.snapshot <- snap

 let set_format cmd format = cmd.format <- format

+let set_image_opts cmd imgopts = cmd.imgopts <- imgopts

-let run_unix socket { disk; snapshot; format } =

+let run_unix socket { disk; snapshot; format; imgopts } =

   assert (disk <> "");

   (* Create a temporary directory where we place the PID file. *)

@@ -85,6 +87,11 @@ let run_unix socket { disk; snapshot; format } =

   (* -s adds a protective overlay. *)

   if snapshot then List.push_back args "-s";

+  (* --image-opts reinterprets the filename parameter as a set of

+   * image options.

+   *)

+  if imgopts then List.push_back args "--image-opts";

+

   if have_selinux && qemu_nbd_has_selinux_label_option () then (

     List.push_back args "--selinux-label";

     List.push_back args "system_u:object_r:svirt_socket_t:s0"

diff --git a/lib/qemuNBD.mli b/lib/qemuNBD.mli

index e10d3106..afe9d944 100644

--- a/lib/qemuNBD.mli

+++ b/lib/qemuNBD.mli

@@ -43,6 +43,11 @@ val set_snapshot : cmd -> bool -> unit

 val set_format : cmd -> string option -> unit

 (** Set the format [--format] parameter. *)

+val set_image_opts : cmd -> bool -> unit

+(** Set whether the [--image-opts] parameter is used.  This changes

+    the meaning of the [filename] parameter to a set of image options.

+    Consult the qemu-nbd man page for more details. *)

+

 val run_unix : string -> cmd -> string * int

 (** Start qemu-nbd command listening on a Unix domain socket,

     waiting for the process to start up.

diff --git a/output/output.ml b/output/output.ml

index 5c6670b9..23c3932d 100644

--- a/output/output.ml

+++ b/output/output.ml

@@ -69,7 +69,7 @@ let error_if_disk_count_gt dir n =

   if Sys.file_exists socket then

     error (f_"this output module doesn't support copying more than %d disks") n

-let output_to_local_file ?(changeuid = fun f -> f ())

+let output_to_local_file ?(changeuid = fun f -> f ()) ?(compressed = false)

       output_alloc output_format filename size socket =

   (* Check nbdkit is installed and has the required plugin. *)

   if not (Nbdkit.is_installed ()) then

@@ -78,6 +78,24 @@ let output_to_local_file ?(changeuid = fun f -> f ())

     error (f_"nbdkit-file-plugin is not installed or not working");

   let nbdkit_config = Nbdkit.config () in

+  if compressed then (

+    (* Only allow compressed with -of qcow2. *)

+    if output_format <> "qcow2" then

+      error (f_"‘-oo compressed’ is only allowed when the output format \

+                is a local qcow2-format file, i.e. ‘-of qcow2’");

+

+    (* Check nbdcopy is new enough.  This assumes that the version of

+     * libnbd is the same as the version of nbdcopy, but parsing this

+     * is easier.  We can remove this check when we build-depend on

+     * libnbd >= 1.14.

+     *)

+    let version =

+      NBD.create () |> NBD.get_version |>

+      String.nsplit "." |> List.map int_of_string in

+    if version < [1; 13; 5] then

+      error (f_"-oo compressed option requires nbdcopy >= 1.13.5")

+  );

+

   let g = open_guestfs () in

   let preallocation =

     match output_alloc with

@@ -103,9 +121,24 @@ let output_to_local_file ?(changeuid = fun f -> f ())

      On_exit.kill pid

   | "qcow2" ->

-     let cmd = QemuNBD.create filename in

+     let cmd =

+       if compressed then (

+         let qemu_quote str = String.replace str "," ",," in

+         let image_opts = [ "driver=compress";

+                            "file.driver=qcow2";

+                            "file.file.driver=file";

+                            "file.file.filename=" ^ qemu_quote filename ] in

+         let image_opts = String.concat "," image_opts in

+         let cmd = QemuNBD.create image_opts in

+         QemuNBD.set_image_opts cmd true;

+         cmd

+       )

+       else (* not compressed *) (

+         let cmd = QemuNBD.create filename in

+         QemuNBD.set_format cmd (Some "qcow2");

+         cmd

+       ) in

      QemuNBD.set_snapshot cmd false;

-     QemuNBD.set_format cmd (Some "qcow2");

      let _, pid = QemuNBD.run_unix socket cmd in

      On_exit.kill pid

diff --git a/output/output.mli b/output/output.mli

index 8d3d6865..c1f0f53d 100644

--- a/output/output.mli

+++ b/output/output.mli

@@ -84,6 +84,7 @@ val error_if_disk_count_gt : string -> int -> unit

     called. *)

 val output_to_local_file : ?changeuid:((unit -> unit) -> unit) ->

+                           ?compressed:bool ->

                            Types.output_allocation ->

                            string -> string -> int64 -> string ->

                            unit