Re: [Qemu-devel] [PATCH] Fix qemu-img can't create qcow image based on read-only image

Kevin Wolf
2010-01-28T09:18:26Z

Am 28.01.2010 06:22, schrieb Sheng Yang:
> Commit 03cbdac7 "Disable fall-back to read-only when cannot open drive's
> file for read-write" result in read-only image can't be used as backed
> image in qemu-img.
>
> CC: Naphtali Sprei <nsprei@redhat.com>
> Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> ---
>
> This issue blocked our QA's KVM nightly test. But in fact, I don't like this
> patch, feeling uncomfortable to change long existed interface... Any
> alternative? Add a readonly command line would change the default behavior(I
> don't think fall back to readonly looks like a bug); or even revert the
> commit? What's the story behind it?
>
> qemu-img.c | 15 ++++++++++-----
> 1 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/qemu-img.c b/qemu-img.c
> index 3cea8ce..f8be5cb 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -188,11 +188,13 @@ static int read_password(char *buf, int buf_size)
> #endif
>
> static BlockDriverState *bdrv_new_open(const char *filename,
> - const char *fmt)
> + const char *fmt,
> + int readonly)
> {
> BlockDriverState *bs;
> BlockDriver *drv;
> char password[256];
> + int flags = BRDV_O_FLAGS;
>
> bs = bdrv_new("");
> if (!bs)
> @@ -204,7 +206,10 @@ static BlockDriverState *bdrv_new_open(const char *filename,
> } else {
> drv = NULL;
> }
> - if (bdrv_open2(bs, filename, BRDV_O_FLAGS | BDRV_O_RDWR, drv) < 0) {
> + if (!readonly) {
> + flags |= BDRV_O_RDWR;
> + }
> + if (bdrv_open2(bs, filename, flags, drv) < 0) {
> error("Could not open '%s'", filename);
> }
> if (bdrv_is_encrypted(bs)) {
> @@ -343,7 +348,7 @@ static int img_create(int argc, char **argv)
> }
> }
>
> - bs = bdrv_new_open(backing_file->value.s, fmt);
> + bs = bdrv_new_open(backing_file->value.s, fmt, 1);
> bdrv_get_geometry(bs, &size);
> size *= 512;
> bdrv_delete(bs);
> @@ -627,7 +632,7 @@ static int img_convert(int argc, char **argv)
>
> total_sectors = 0;
> for (bs_i = 0; bs_i < bs_n; bs_i++) {
> - bs[bs_i] = bdrv_new_open(argv[optind + bs_i], fmt);
> + bs[bs_i] = bdrv_new_open(argv[optind + bs_i], fmt, 0);

Shouldn't it be read-only here, too?

Kevin