From 33b3a097b4b7720d4d43ebe15e9881e976f70e4b Mon Sep 17 00:00:00 2001

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

Date: Tue, 22 Oct 2013 13:52:25 +0100

Subject: [PATCH] builder: Don't run virt-resize when not necessary.

If:

 - the output is a regular file

 - the output format is raw

 - the user didn't specify the --size option

then we don't need to run virt-resize.  Simply uncompress

the template directly to the output file.

(cherry picked from commit 2f3a3e308af8012501437f723471a66537ecbf64)

---

 builder/builder.ml | 70 +++++++++++++++++++++++++++++++++++++-----------------

 1 file changed, 48 insertions(+), 22 deletions(-)

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

index 25ab8c4..16005e1 100644

--- a/builder/builder.ml

+++ b/builder/builder.ml

@@ -232,7 +232,12 @@ let main () =

       Sigchecker.verify_detached sigchecker template sigfile in

-  let output, size, format, delete_output_file, resize_sparse =

+  (* Plan how to create the output.  This depends on:

+   * - did the user specify --output?

+   * - is the output a block device?

+   * - did the user specify --size?

+   *)

+  let output, size, format, delete_output_file, do_resize, resize_sparse =

     let is_block_device file =

       try (stat file).st_kind = S_BLK

       with Unix_error _ -> false

@@ -259,22 +264,22 @@ let main () =

       (* Dummy: The output file is never deleted in this case. *)

       let delete_output_file = ref false in

-      output, None, format, delete_output_file, false

+      output, None, format, delete_output_file, true, false

     (* Regular file output.  Note the file gets deleted. *)

     | _ ->

       (* Check the --size option. *)

-      let size =

+      let size, do_resize =

         let { Index_parser.size = default_size } = entry in

         match size with

-        | None -> default_size +^ headroom

+        | None -> default_size, false

         | Some size ->

           if size < default_size +^ headroom then (

             eprintf (f_"%s: --size is too small for this disk image, minimum size is %s\n")

               prog (human_size default_size);

             exit 1

           );

-          size in

+          size, true in

       (* Create the output file. *)

       let output, format =

@@ -285,6 +290,14 @@ let main () =

         | Some output, None -> output, "raw"

         | Some output, Some format -> output, format in

+      (* If the input format != output format then we must run virt-resize. *)

+      let do_resize =

+        let input_format =

+          match entry with

+          | { Index_parser.format = Some format } -> format

+          | { Index_parser.format = None } -> "raw" in

+        if input_format <> format then true else do_resize in

+

       msg (f_"Creating disk image: %s") output;

       let cmd =

         sprintf "qemu-img create -f %s%s %s %Ld%s"

@@ -308,30 +321,42 @@ let main () =

       in

       at_exit delete_file;

-      output, Some size, format, delete_output_file, true in

+      output, Some size, format, delete_output_file, do_resize, true in

-  if is_char_device output then (

-    eprintf (f_"%s: cannot output to a character device or /dev/null\n") prog;

-    exit 1

-  );

-

-  let source =

-    (* Uncompress it to a temporary file. *)

+  if not do_resize then (

+    (* If the user did not specify --size and the output is a regular

+     * file and the format is raw, then we just uncompress the template

+     * directly to the output file.  This is fast but less flexible.

+     *)

     let { Index_parser.file_uri = file_uri } = entry in

-    let tmpfile = Filename.temp_file "vbsrc" ".img" in

-    let cmd = sprintf "xzcat %s > %s" (quote template) (quote tmpfile) in

+    let cmd = sprintf "xzcat %s > %s" (quote template) (quote output) in

     if debug then eprintf "%s\n%!" cmd;

     msg (f_"Uncompressing: %s") file_uri;

     let r = Sys.command cmd in

     if r <> 0 then (

       eprintf (f_"%s: error: failed to uncompress template\n") prog;

       exit 1

-    );

-    unlink_on_exit tmpfile;

-    tmpfile in

+    )

+  ) else (

+    (* If none of the above apply, uncompress to a temporary file and

+     * run virt-resize on the result.

+     *)

+    let tmpfile =

+      (* Uncompress it to a temporary file. *)

+      let { Index_parser.file_uri = file_uri } = entry in

+      let tmpfile = Filename.temp_file "vbsrc" ".img" in

+      let cmd = sprintf "xzcat %s > %s" (quote template) (quote tmpfile) in

+      if debug then eprintf "%s\n%!" cmd;

+      msg (f_"Uncompressing: %s") file_uri;

+      let r = Sys.command cmd in

+      if r <> 0 then (

+        eprintf (f_"%s: error: failed to uncompress template\n") prog;

+        exit 1

+      );

+      unlink_on_exit tmpfile;

+      tmpfile in

-  (* Resize the source to the output file. *)

-  let () =

+    (* Resize the source to the output file. *)

     (match size with

     | None ->

       msg (f_"Running virt-resize to expand the disk")

@@ -356,13 +381,14 @@ let main () =

         (match lvexpand with

         | None -> ""

         | Some lvexpand -> sprintf " --lv-expand %s" (quote lvexpand))

-        (quote source) (quote output) in

+        (quote tmpfile) (quote output) in

     if debug then eprintf "%s\n%!" cmd;

     let r = Sys.command cmd in

     if r <> 0 then (

       eprintf (f_"%s: error: virt-resize failed\n") prog;

       exit 1

-    ) in

+    )

+  );

   (* Now mount the output disk so we can make changes. *)

   msg (f_"Opening the new disk");

-- 

1.8.4.2