Re: [Qemu-devel] [PATCH v3 11/14] qemu-io: Use BlockBackend

[Eric Blake <eblake@redhat.com>]

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On 01/26/2015 08:00 AM, Max Reitz wrote:
> qemu-io should behave like a guest, therefore it should use BlockBackend
> to access the block layer.
> 
> There are a couple of places where that is infeasible: First, the
> bdrv_debug_* functions could theoretically be mirrored in the
> BlockBackend, but since these are functions internal to the block layer,
> they should not be visible externally (qemu-io as a test tool is excempt

s/excempt/exempt/

> from this).
> 
> Second, bdrv_get_info() and bdrv_get_specific_info() work on a single
> BDS alone, therefore they should stay BDS-specific.
> 
> Third, bdrv_is_allocated() mainly works on a single BDS as well. Some
> data may be passed through from the BDS's file (if sectors which are
> apparently allocated in the file are not really allocated there but just
> zero).
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---

> -static int map_f(BlockDriverState *bs, int argc, char **argv)
> +static int map_f(BlockBackend *blk, int argc, char **argv)
>  {
>      int64_t offset;
> -    int64_t nb_sectors;
> +    int64_t nb_sectors, total_sectors;
>      char s1[64];
>      int64_t num;
>      int ret;
>      const char *retstr;
>  
>      offset = 0;
> -    nb_sectors = bs->total_sectors;
> +    total_sectors = blk_getlength(blk);
> +    if (total_sectors < 0) {
> +        error_report("Failed to query image length: %s",
> +                     strerror(-total_sectors));
> +        return 0;
> +    }
> +
> +    total_sectors /= BDRV_SECTOR_SIZE;

Another spot that would benefit from a (possibly temporary)
bdrv_nb_sectors().

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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