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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 C91FCC433B4 for ; Tue, 11 May 2021 21:21:11 +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 422E4611BD for ; Tue, 11 May 2021 21:21:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 422E4611BD 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]:42322 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lgZoU-0003E7-5k for qemu-devel@archiver.kernel.org; Tue, 11 May 2021 17:21:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48634) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lgZnO-0002UW-1B for qemu-devel@nongnu.org; Tue, 11 May 2021 17:20:02 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:56919) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lgZnM-0003E9-Bc for qemu-devel@nongnu.org; Tue, 11 May 2021 17:20:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620767999; 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=Zz2TZoZAdE8VAeNTejy6giwfeJ55+u8GX7WefZDJhV8=; b=SzwC2gf5MvUrVTgKd4WsQ1tPrU3SM1mRZcPvERT4f/jMU1WS22iWLOZ/D9mqo7cBHc7Kfa 6vPSHHjceenof6P7GX7fvi5m67gUkfmyNF9/Vcm+F6ECnEaE6UO+ayvBQsefD5/v2F+Q0v 3zQ67iAMcXYpVu4CT0R1Uclr3sOt1hM= 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-116-Dqf6T75pP5uXqNSruLaiRA-1; Tue, 11 May 2021 17:19:56 -0400 X-MC-Unique: Dqf6T75pP5uXqNSruLaiRA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ADA171854E24; Tue, 11 May 2021 21:19:54 +0000 (UTC) Received: from [10.3.114.221] (ovpn-114-221.phx2.redhat.com [10.3.114.221]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 965FC2B198; Tue, 11 May 2021 21:19:46 +0000 (UTC) Subject: Re: [PATCH v4 06/11] block: make BlockLimits::max_pwrite_zeroes 64bit To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org References: <20210324205132.464899-1-vsementsov@virtuozzo.com> <20210324205132.464899-7-vsementsov@virtuozzo.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: <94bc702a-99a4-9a94-cf9b-6c67f4cf1fd2@redhat.com> Date: Tue, 11 May 2021 16:19:45 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210324205132.464899-7-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=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: fam@euphon.net, kwolf@redhat.com, integration@gluster.org, berto@igalia.com, stefanha@redhat.com, pavel.dovgaluk@ispras.ru, sw@weilnetz.de, pl@kamp.de, qemu-devel@nongnu.org, mreitz@redhat.com, jsnow@redhat.com, ronniesahlberg@gmail.com, pbonzini@redhat.com, namei.unix@gmail.com, dillaman@redhat.com, ari@tuxera.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/24/21 3:51 PM, Vladimir Sementsov-Ogievskiy wrote: > We are going to support 64 bit write-zeroes requests. Now update the > limit variable. It's absolutely safe. The variable is set in some > drivers, and used in bdrv_co_do_pwrite_zeroes(). > > Update also max_write_zeroes variable in bdrv_co_do_pwrite_zeroes(), so > that bdrv_co_do_pwrite_zeroes() is now prepared to 64bit requests. The > remaining logic including num, offset and bytes variables is already > supporting 64bit requests. > > So the only thing that prevents 64 bit requests is limiting > max_write_zeroes variable to INT_MAX in bdrv_co_do_pwrite_zeroes(). > We'll drop this limitation after updating all block drivers. > > Ah, we also have bdrv_check_request32() in bdrv_co_pwritev_part(). It > will be modified to do bdrv_check_request() for write-zeroes path. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > include/block/block_int.h | 7 +++---- > block/io.c | 2 +- > 2 files changed, 4 insertions(+), 5 deletions(-) > > +++ b/include/block/block_int.h > @@ -676,10 +676,9 @@ typedef struct BlockLimits { > * that is set. May be 0 if bl.request_alignment is good enough */ > uint32_t pdiscard_alignment; > > - /* Maximum number of bytes that can zeroized at once (since it is > - * signed, it must be < 2G, if set). Must be multiple of > - * pwrite_zeroes_alignment. May be 0 if no inherent 32-bit limit */ > - int32_t max_pwrite_zeroes; > + /* Maximum number of bytes that can zeroized at once. Must be multiple of > + * pwrite_zeroes_alignment. May be 0 if no inherent 64-bit limit */ Is the comment still right? Leaving as 0 is the easiest way for a driver to say "default limit", but I would feel safer with the default being 2G-align rather than 63-bit limit. And it is a 63-bit limit, not 64-bit, if the driver opts in to INT64_MAX. > + int64_t max_pwrite_zeroes; > > /* Optimal alignment for write zeroes requests in bytes. A power > * of 2 is best but not mandatory. Must be a multiple of > diff --git a/block/io.c b/block/io.c > index 55095dd08e..79e600af27 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -1836,7 +1836,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, > int head = 0; > int tail = 0; > > - int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX); > + int64_t max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX); You are correct that for now we have no behavior change; a driver opting in to a larger limit will still be clamped until we revisit this patch later to drop the MIN() - but I agree with your approach of keeping MIN() here until all drivers are audited. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org