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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 3F153C433EF for ; Mon, 20 Sep 2021 04:48:21 +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 971A660FED for ; Mon, 20 Sep 2021 04:48:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 971A660FED Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:53732 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mSBE3-0005K7-AY for qemu-devel@archiver.kernel.org; Mon, 20 Sep 2021 00:48:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44782) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mSBD8-0004en-AE for qemu-devel@nongnu.org; Mon, 20 Sep 2021 00:47:22 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:43982) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mSBD4-00084a-H7 for qemu-devel@nongnu.org; Mon, 20 Sep 2021 00:47:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632113236; 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=jxsVjGAvuJSX7vAe8a6z4f9CpaqwuOw01xugjSFrmWY=; b=b9shgCf3Kt1izECuCuc2KlHvvD+Vc9nacKZQ8ZFP/djxMICbQ3wV2Z4sCCGk6busfIB+Nn nJrRdrR3vDKiwsYd7fOHJV9vuUMyds6SOEWLffHq7Lei00lDnsqaIOuZPmSdtp3cUabb0M tRsalN6roAu9o7JkTWqyGWPMdIldBZM= 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-160-q8h3VSwkMc-P002WIvBL_g-1; Mon, 20 Sep 2021 00:47:13 -0400 X-MC-Unique: q8h3VSwkMc-P002WIvBL_g-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 44E501006AA3; Mon, 20 Sep 2021 04:47:12 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-14.ams2.redhat.com [10.36.112.14]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F3D6A6B54B; Mon, 20 Sep 2021 04:47:11 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 636AC113865F; Mon, 20 Sep 2021 06:47:10 +0200 (CEST) From: Markus Armbruster To: lishan Subject: Re: [PATCH] block/file-posix: Limit max_iov to IOV_MAX References: <20210918040658.19484-1-lishan24@huawei.com> Date: Mon, 20 Sep 2021 06:47:10 +0200 In-Reply-To: <20210918040658.19484-1-lishan24@huawei.com> (lishan's message of "Sat, 18 Sep 2021 12:06:58 +0800") Message-ID: <87lf3rn99t.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.476, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, eric.fangyi@huawei.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" lishan writes: > AIO read/write. The size of iocb->aio_nbytes in the kernel cannot exceed UIO_MAXIOV = 1024. > max_segments read from the block device layer may be greater than UIO_MAXIOV, > this causes the ioq_submit interface to return a -22(-EINVAL) error result. > --- > block/file-posix.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index d81e15efa4..137e27e47b 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -1273,7 +1273,8 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp) > > ret = hdev_get_max_segments(s->fd, &st); > if (ret > 0) { > - bs->bl.max_iov = ret; > + /* The maximum segment size allowed by the kernel is UIO_MAXIOV = 1024. */ > + bs->bl.max_iov = MIN(ret, IOV_MAX); > } > } > } I didn't check your assertion we always need to cap at IOV_MAX. Assuming you're right, why not do it in hdev_get_max_segments()?