Re: [Qemu-devel] [Qemu-block] [PATCH 1/2] qcow2: Do not mark inactive images corrupt

[Jeff Cody <jcody@redhat.com>]

On Mon, Jun 04, 2018 at 04:14:36PM +0200, Max Reitz wrote:
> When signaling a corruption on a read-only image, qcow2 already makes
> fatal events non-fatal (i.e., they will not result in the image being
> closed, and the image header's corrupt flag will not be set).  This is
> necessary because we cannot set the corrupt flag on read-only images,
> and it is possible because further corruption of read-only images is
> impossible.
> 
> Inactive images are effectively read-only, too, so we should do the same
> for them.
> 
> (Otherwise, the assert(!(bs->open_flags & BDRV_O_INACTIVE)) in
> bdrv_co_pwritev() will fail, crashing qemu.)
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/qcow2.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 59a38b9cd3..8b5f7386f7 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -4402,7 +4402,9 @@ void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
>      char *message;
>      va_list ap;
>  
> -    fatal = fatal && !bs->read_only;
> +    if ((bs->open_flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) != BDRV_O_RDWR) {

Hmm, this is pretty much exactly what the bdrv_is_writable() helper function
does in block.c; too bad it's scope is limited to block.c.  Maybe worth it
to make it a more widely available helper and use it here?

> +        fatal = false;
> +    }
>  
>      if (s->signaled_corruption &&
>          (!fatal || (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT)))
> -- 
> 2.17.0
> 
>