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

[Kevin Wolf <kwolf@redhat.com>]

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