Am 29.04.2011 03:42, schrieb Brad Campbell:
> G'day all,
>
> This patch makes qemu-img properly consider the contents of the output
> backing file when performing a convert operation. All things considered
> it would also perform similar to rebase, where you could specify a
> completely different backing file and it would just de-dup.
>
> I've poked this in as an attachment as apparently my last attempt at an
> in-line patch munged the formatting.
>
> Comments, pokes or flames welcome.
Please include a commit comment and a Signed-off-by line. Instead of
sending a plain diff, you'll get a better result if you have a git
commit locally and use git format-patch to create the patch file.
Also please make sure to avoid trailing whitespace.
> > @@ -719,6 +720,16 @@ static int img_convert(int argc, char **argv)
> out_baseimg_param = get_option_parameter(param, BLOCK_OPT_BACKING_FILE);
> if (out_baseimg_param) {
> out_baseimg = out_baseimg_param->value.s;
> +
> + /* out_baseimg_parm != NULL even if there is no base img specified!
> */
> + if (out_baseimg) {
> + out_bf = bdrv_new_open(out_baseimg, NULL, BDRV_O_FLAGS);
> + if (!out_bf) {
> + error_report("Could not open backing file '%s'",
> out_baseimg);
> + ret = -1;
> + goto out;
>
bdrv_new_open already prints an error message in case of failure, so we
shouldn't duplicate it here.
> @@ -889,8 +903,15 @@ static int img_convert(int argc, char **argv)
> are present in both the output's and input's base images
> (no
> need to copy them). */
> if (out_baseimg) {
> - if (!bdrv_is_allocated(bs[bs_i], sector_num - bs_offset,
> - n, &n1)) {
> + if (bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n)
> < 0) {
> + error_report("error while reading input file");
> + goto out;
> + }
> + if (bdrv_read(out_bf, sector_num - bs_offset, buf3, n) <
> 0) {
> + error_report("error while reading backing file");
> + goto out;
> + }
Did you test what happens with a backing file that is smaller than the
overlay? I suspect it will fail here after this change.
Also I think you need to set ret = -1 before jumping to out:
Kevin
