Re: [Qemu-block] [PATCH 01/11] block: Use writeback in .bdrv_create() implementations

[Kevin Wolf]

Am 09.03.2016 um 13:14 hat Paolo Bonzini geschrieben:
> 
> 
> On 08/03/2016 17:34, Kevin Wolf wrote:
> > There's no reason to use a writethrough cache mode while creating an
> > image.
> 
> There's no reason to do flushes in fact, so you could use
> BDRV_O_NO_FLUSH too. :)

That's true. On the other hand, we don't issue flushes anyway, so
there's little reason to ignore non-existing flushes. :-)

The only part where it might make sense is where image formats don't
open the raw image file, but actually open the image with themselves and
allocate things. qcow2 at least already sets BDRV_O_NO_FLUSH for that
part.

In fact, the only bdrv_open() touched in this patch that doesn't have
BDRV_O_PROTOCOL set, is one instance in VMDK where it opens the backing
file to read some ID from the header. So no flush involved there.

Kevin