From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39203) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fIAkZ-0003fz-8i for qemu-devel@nongnu.org; Mon, 14 May 2018 06:30:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fIAkT-0003St-BY for qemu-devel@nongnu.org; Mon, 14 May 2018 06:30:39 -0400 From: Alberto Garcia In-Reply-To: <1525791496-125188-5-git-send-email-anton.nefedov@virtuozzo.com> References: <1525791496-125188-1-git-send-email-anton.nefedov@virtuozzo.com> <1525791496-125188-5-git-send-email-anton.nefedov@virtuozzo.com> Date: Mon, 14 May 2018 12:29:55 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v9 4/9] block: introduce BDRV_REQ_ALLOCATE flag List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anton Nefedov , qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, kwolf@redhat.com, mreitz@redhat.com, eblake@redhat.com, den@virtuozzo.com On Tue 08 May 2018 04:58:11 PM CEST, Anton Nefedov wrote: > The flag is supposed to indicate that the region of the disk image has > to be sufficiently allocated so it reads as zeroes. > > The call with the flag set must return -ENOTSUP if allocation cannot > be done efficiently. > This has to be made sure of by both > - the drivers that support the flag > - and the common block layer (so it will not fall back to any slowpath > (like writing zero buffers) in case the driver does not support > the flag). > > Signed-off-by: Anton Nefedov Reviewed-by: Alberto Garcia Berto