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 ABAF5C369B2 for ; Thu, 17 Apr 2025 08:51:26 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u5KxK-0002oC-QY; Thu, 17 Apr 2025 04:50:46 -0400 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 1u5Kwn-0002e4-Rw for qemu-devel@nongnu.org; Thu, 17 Apr 2025 04:50:17 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u5Kwj-0007fQ-Ra for qemu-devel@nongnu.org; Thu, 17 Apr 2025 04:50:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744879807; 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=j+arAyjKguR7Otm5vGIyKBbqn5sbrA0N5beoC9ueSGg=; b=gzznUlmrFezzPewiZ/HXWBp2YATDG4F+qxPxEH7MYMXyDHmXmtUYnXviSj2FIDykLktGPg 1k77BKbFV+1IEpmzVBF8/lX9BacORIhdg6hc6EXNY3UzN04cxoLw4dC4k/punVXOkpOcET siwy/iLK8MvairMMAAMEXwv1cmxL4eU= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-491-p867Bn53PHuJAyCxi40nPQ-1; Thu, 17 Apr 2025 04:50:03 -0400 X-MC-Unique: p867Bn53PHuJAyCxi40nPQ-1 X-Mimecast-MFC-AGG-ID: p867Bn53PHuJAyCxi40nPQ_1744879802 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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C97A7180087A; Thu, 17 Apr 2025 08:50:00 +0000 (UTC) Received: from redhat.com (unknown [10.45.225.158]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5839B18002AD; Thu, 17 Apr 2025 08:49:57 +0000 (UTC) Date: Thu, 17 Apr 2025 10:49:55 +0200 From: Kevin Wolf To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Hanna Reitz , qemu-block@nongnu.org, Fam Zheng , eblake@redhat.com Subject: Re: [PATCH v3 2/2] block/io: skip head/tail requests on EINVAL Message-ID: References: <20250414201214.241351-1-stefanha@redhat.com> <20250414201214.241351-3-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250414201214.241351-3-stefanha@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=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: 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 Am 14.04.2025 um 22:12 hat Stefan Hajnoczi geschrieben: > When guests send misaligned discard requests, the block layer breaks > them up into a misaligned head, an aligned main body, and a misaligned > tail. > > The file-posix block driver on Linux returns -EINVAL on misaligned > discard requests. This causes bdrv_co_pdiscard() to fail and guests > configured with werror=stop will pause. > > Add a special case for misaligned head/tail requests. Simply continue > when EINVAL is encountered so that the aligned main body of the request > can be completed and the guest is not paused. This is the best we can do > when guest discard limits do not match the host discard limits. > > Fixes: https://issues.redhat.com/browse/RHEL-86032 > Signed-off-by: Stefan Hajnoczi > Reviewed-by: Hanna Czenczek It would be good to also update the comment a bit further up: /* Discard is advisory, but some devices track and coalesce * unaligned requests, so we must pass everything down rather than * round here. Still, most devices will just silently ignore * unaligned requests (by returning -ENOTSUP), so we must fragment * the request accordingly. */ I'm not sure where the -ENOTSUP came from (Eric, do you remember?), but we should at least mention this -EINVAL case separately. Kevin