Re: [Qemu-devel] [RFC PATCH] block: optimize zero writes with bdrv_write_zeroes

[Fam Zheng]

On Mon, 02/24 11:39, Paolo Bonzini wrote:
> Il 24/02/2014 02:01, Fam Zheng ha scritto:
> >
> >I would do this in qcow2:
> >
> > 1. In qcow2_co_writev, allocate cluster regardless of if data is zero or 
> > not.
> > 2. If data is zero, set QCOW2_OFLAG_ZERO in L2.
> 
> This is (or should be) bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP.

But IIUC bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP doesn't require
cluster allocation if it's allocated yet, which is a bit different.

Fam