Am 07.10.2013 um 10:42 schrieb Stefan Hajnoczi <stefa...@gmail.com>:
> On Tue, Sep 24, 2013 at 03:34:54PM +0200, Peter Lieven wrote: >> this patch adds the ability for targets to stay sparse during >> block migration (if the zero_blocks capability is set) and qemu-img convert >> even if the target does not have has_zero_init = 1. >> >> the series was especially developed for iSCSI, but it should also work >> with other drivers with little or no adjustments. these adjustments >> should be limited to providing block provisioning information through >> get_block_info and/or honouring BDRV_REQ_MAY_UNMAP on writing zeroes. > > Could you make bdrv_co_write_zeroes() always use UNMAP, if possible, and > avoid adding the new BDRV_REQ_MAY_UNMAP flag? While reading the first > few patches in this series I wondered why there is a need to expose > flags at all... > > Sometimes it is useful to distinguish between zeroing at the image > format level from discarding at the device level, but I don't think we > make use of that yet. I'd prefer to keep the interface simple for now > and add flags later, if necessary. > > Or maybe I just missed something ;) > There was a big discussing going on on this flags some time ago with Paolo and Kevin and they wanted to have it. (thread was "qemu-img: conditionally discard target on convert"). For my use case I don't need the flag. Peter
