[Qemu-devel] Re: [PATCH 1/4] block: clarify the meaning of BDRV_O_NOCACHE

[Kevin Wolf <kwolf@redhat.com>]

Am 16.03.2011 18:00, schrieb Stefan Hajnoczi:
> On Wed, Mar 16, 2011 at 2:08 PM, Christoph Hellwig <hch@lst.de> wrote:
>> On Wed, Mar 16, 2011 at 09:42:37AM +0000, Stefan Hajnoczi wrote:
>>> -    writethrough = ((flags & BDRV_O_CACHE_MASK) == 0);
>>> +    writethrough = ((flags & (BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)) == 0);
>>
>> or rather
>>
>>        writethrough = ((flags & (BDRV_O_CACHE_WB) != );
>>
>> but yes, this code had sneaked in since my initial version.
> 
> My intention was that if we don't care about honoring flushes then we
> might as well use Qcow2Cache.  But yes, just checking for cache mode
> is the clearest.

You mean for a possible writethrough mode with BDRV_O_NO_FLUSH set? Such
a mode doesn't make a lot of sense to me.

Kevin