Re: [Qemu-devel] [PATCH 3/3] Combine bdrv_co_readv and bdrv_co_writev into bdrv_co_rw_vector

[Paolo Bonzini <pbonzini@redhat.com>]

Il 29/02/2012 00:54, Michael Tokarev ha scritto:
>      BlockDriver *drv = bs->drv;
>      BdrvTrackedRequest req;
> +    bool is_write = flags & (BDRV_REQ_WRITE|BDRV_REQ_ZERO_WRITE);
>      int ret;

You can do BDRV_REQ_WRITE|BDRV_REQ_ZERO_WRITE, but not
BDRV_REQ_READ|BDRV_REQ_COPY_ON_READ.  That's ugly.

> +/* defines for is_write for bdrv_*_rw_vector */
> +#define BDRV_READ	false
> +#define BDRV_WRITE	true
> +

Please no, if you have to do this just change to bits.  This would have
the advantage of passing all the flags, including COPY_ON_READ.  In some
sense discard could be treated as a write too.

I don't oppose this change completely, in fact I think adding the flags
to co_readv/co_writev would be a good change.  But I'm skeptical, the
actual amount of unification is not that large.

Paolo