From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BE15C83000 for ; Tue, 28 Apr 2020 14:05:58 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 045B0206C0 for ; Tue, 28 Apr 2020 14:05:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DJoAtD9d" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 045B0206C0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59154 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jTQs1-0004e4-3g for qemu-devel@archiver.kernel.org; Tue, 28 Apr 2020 10:05:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39564) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jTQqC-0000Pn-Gu for qemu-devel@nongnu.org; Tue, 28 Apr 2020 10:04:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.90_1) (envelope-from ) id 1jTQns-0001F9-Lt for qemu-devel@nongnu.org; Tue, 28 Apr 2020 10:03:54 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:33622 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jTQns-000175-79 for qemu-devel@nongnu.org; Tue, 28 Apr 2020 10:01:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588082499; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=s9XojcR2WzAFRWPQei00xciuaekP126HvcOc8XWGBKE=; b=DJoAtD9dpR7oV3QFV/COaK4tRBp1XyF6y6hp6FsuXNgqbYQjkbA0q2UmrKOc1yq740HKMt qffVeDPO3DGShHLW96dbVhfJjB3NNRe9Pmvdq/SCSl4e46Et11qVUFeJKnCAgThJ75CvTQ L4bY2cP4vWYjDHJIp80zUgCg4sbG+HQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-444-Vn0xGMd1NLaozspoBlxb9w-1; Tue, 28 Apr 2020 10:01:37 -0400 X-MC-Unique: Vn0xGMd1NLaozspoBlxb9w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8190F80572D; Tue, 28 Apr 2020 14:01:35 +0000 (UTC) Received: from linux.fritz.box (ovpn-114-37.ams2.redhat.com [10.36.114.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 640BE1C950; Tue, 28 Apr 2020 14:01:33 +0000 (UTC) Date: Tue, 28 Apr 2020 16:01:32 +0200 From: Kevin Wolf To: Eric Blake Subject: Re: [PATCH 1/4] block: Add bdrv_make_empty() Message-ID: <20200428140132.GF5789@linux.fritz.box> References: <20200428132629.796753-1-mreitz@redhat.com> <20200428132629.796753-2-mreitz@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=kwolf@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/28 02:16:38 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 28.04.2020 um 15:53 hat Eric Blake geschrieben: > On 4/28/20 8:26 AM, Max Reitz wrote: > > Right now, all users of bdrv_make_empty() call the BlockDriver method > > directly. That is not only bad style, it is also wrong, unless the > > caller has a BdrvChild with a WRITE permission. > >=20 > > Introduce bdrv_make_empty() that verifies that it does. > >=20 > > Signed-off-by: Max Reitz > > --- > > include/block/block.h | 1 + > > block.c | 23 +++++++++++++++++++++++ > > 2 files changed, 24 insertions(+) > >=20 > > diff --git a/include/block/block.h b/include/block/block.h > > index b05995fe9c..d947fb4080 100644 > > --- a/include/block/block.h > > +++ b/include/block/block.h > > @@ -351,6 +351,7 @@ BlockMeasureInfo *bdrv_measure(BlockDriver *drv, Qe= muOpts *opts, > > void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr= ); > > void bdrv_refresh_limits(BlockDriverState *bs, Error **errp); > > int bdrv_commit(BlockDriverState *bs); > > +int bdrv_make_empty(BdrvChild *c, Error **errp); >=20 > Can we please fix this to take a flags parameter? I want to make it easi= er > for callers to request BDRV_REQ_NO_FALLBACK for distinguishing between > callers where the image must be made empty (read as all zeroes) regardles= s > of time spent, vs. made empty quickly (including if it is already all zer= o) > but where the caller is prepared for the operation to fail and will write > zeroes itself if fast bulk zeroing was not possible. bdrv_make_empty() is not for making an image read as all zeroes, but to make it fully unallocated so that the backing file becomes visible. Are you confusing it with bdrv_make_zero(), which is just a wrapper around bdrv_pwrite_zeroes() and does take flags? Kevin