Re: [Qemu-devel] [PATCH] block: fix the use of protocols in backing files

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

On 11/04/2010 07:54 AM, Kevin Wolf wrote:
> Am 27.10.2010 20:19, schrieb Anthony Liguori:
>    
>> Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>
>>
>> diff --git a/block.c b/block.c
>> index 1a965b2..00b6f21 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -603,10 +603,16 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
>>           BlockDriver *back_drv = NULL;
>>
>>           bs->backing_hd = bdrv_new("");
>> -        path_combine(backing_filename, sizeof(backing_filename),
>> -                     filename, bs->backing_file);
>> -        if (bs->backing_format[0] != '\0')
>> -            back_drv = bdrv_find_format(bs->backing_format);
>> +        back_drv = bdrv_find_protocol(bs->backing_file);
>> +        if (!back_drv) {
>>      
> If no protocol is specified, bdrv_find_protocol doesn't return NULL but
> the file: driver.
>    

An ugly way to handle this would be to do if (strstr(bs->backing_file, 
":") == NULL) instead.

A deeper refactoring could return NULL in bdrv_find_protocol and fixup 
the callers to default to file: if none are specified.

What do you think?

Regards,

Anthony Liguori



> This breaks all backing file related qemu-iotests cases because qcow2
> backing files are opened as raw files now.
>
> Kevin
>