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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 7E881E9129F for ; Thu, 5 Feb 2026 15:27:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vo1FY-0006l1-M1; Thu, 05 Feb 2026 10:26:32 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vo1FV-0006Xi-C3 for qemu-devel@nongnu.org; Thu, 05 Feb 2026 10:26:29 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vo1FT-0002Ep-F2 for qemu-devel@nongnu.org; Thu, 05 Feb 2026 10:26:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770305186; 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: in-reply-to:in-reply-to:references:references; bh=0+6xYAVkQfp2Z6/Nejqf0oLU3jhPsBVhnRzU5KH2pf4=; b=MqaJF9L2Bln9egMzcWVK4fPX94SBqEtFD/x+pYO+uoEekIS6GrV6R39ZUcV9oCsHsjv6A9 TSsRFQr7y7DVOWQkuMgxa5HlIH9YFuzzhKdrul0tfcM9Lgmu9rOPEzmTcvZ2JD7ELbt9GD I8eu9Uj7nRLoLfMvvAxmn+taeV/t0Gw= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-680-yLMIflo0P8aCMmo0X6rtEg-1; Thu, 05 Feb 2026 10:26:21 -0500 X-MC-Unique: yLMIflo0P8aCMmo0X6rtEg-1 X-Mimecast-MFC-AGG-ID: yLMIflo0P8aCMmo0X6rtEg_1770305180 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B6E271956089; Thu, 5 Feb 2026 15:26:19 +0000 (UTC) Received: from localhost (unknown [10.2.16.72]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 883AE18003F6; Thu, 5 Feb 2026 15:26:18 +0000 (UTC) Date: Thu, 5 Feb 2026 10:26:17 -0500 From: Stefan Hajnoczi To: Fiona Ebner Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, hreitz@redhat.com, kwolf@redhat.com, fam@euphon.net Subject: Re: [RFC v2 0/6] block/io: avoid failure caused by misaligned BLKZEROOUT ioctl Message-ID: <20260205152617.GA42182@fedora> References: <20260109120837.2772961-1-f.ebner@proxmox.com> <20260202221634.GB429972@fedora> <36a69637-d7b9-42cb-b16f-473091efb3ee@proxmox.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ejteCY3YyPjFawx0" Content-Disposition: inline In-Reply-To: <36a69637-d7b9-42cb-b16f-473091efb3ee@proxmox.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --ejteCY3YyPjFawx0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Feb 05, 2026 at 01:13:57PM +0100, Fiona Ebner wrote: > Hi Stefan, >=20 > Am 02.02.26 um 11:15 PM schrieb Stefan Hajnoczi: > > On Fri, Jan 09, 2026 at 01:08:27PM +0100, Fiona Ebner wrote: > >> Previous discussion here: > >> https://lore.kernel.org/qemu-devel/20260105143416.737482-1-f.ebner@pro= xmox.com/ > >> > >> Commit 5634622bcb ("file-posix: allow BLKZEROOUT with -t writeback") > >> enables the BLKZEROOUT ioctl when using 'writeback' cache, regressing > >> certain 'qemu-img convert' invocations, because of a pre-existing > >> issue. Namely, the BLKZEROOUT ioctl might fail with errno EINVAL when > >> the request is shorter than the block size of the block device. > >> > >> Stefan suggested prioritizing bl.pwrite_zeroes_alignment in > >> bdrv_co_do_zero_pwritev(). This RFC explores that approach and the > >> issues with qcow2 I encountered, where > >> bl.pwrite_zeroes_alignment =3D s->subcluster_size; > >> I would be happy to discuss potential solutions and whether we should > >> use this approach after all. > >=20 > > Hi Fiona, > > I wanted to continue this discussion. My thoughts are that making > > bdrv_co_do_zero_pwritev() use bl.pwrite_zeroes_alignment is the right > > long-term solution to keep all the padding logic in one place. > >=20 > > On the other hand, your series shows it involves fixing a bunch of test > > failures and that's not fun. The original bug that is being solved here > > is my doing, so feel free to hand this over to me if you decide you > > don't want to work on it. >=20 > in your other mail, you mentioned you'll ask Kevin for his opinion. So > in part, I was waiting for that. But I also was side-tracked by other > things, and it will be 1-2 more weeks until I can really focus on this > again. If that is too long, please go ahead and pick it up. I have pinged him now. My timeframe is similar. I can look into this as a background task and if I make progress I'll share it with you. 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