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=-15.3 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 14DEDC433E0 for ; Fri, 22 Jan 2021 16:22:09 +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 9D9552343E for ; Fri, 22 Jan 2021 16:22:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D9552343E 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]:53428 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l2zCJ-0004sD-Ix for qemu-devel@archiver.kernel.org; Fri, 22 Jan 2021 11:22:07 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50320) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l2z9T-0003mC-1w for qemu-devel@nongnu.org; Fri, 22 Jan 2021 11:19:11 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:53575) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l2z9N-0005g7-66 for qemu-devel@nongnu.org; Fri, 22 Jan 2021 11:19:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611332342; 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=38Ax5xJXa7fphoim04bLzHm+wuyZy34FTUDmHm399jo=; b=i1UwYEy50UtsIkRHXnK8J6OKtyaCNhYQGOSiGEozKP6Uts/PK3JNMJAFHyeVGelc+oqgmp AoNJbv0raoK1XVvb2ojt7cFsNril/8K4oNVOdIc5mRlJ1mIy/71ezMLoDSIAG+ssu30js4 o37qa+fDx1T7ffn89b6wbcRFpG0ThAE= 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-217-hTdic4UiM8KsXr3UqlAArw-1; Fri, 22 Jan 2021 11:18:59 -0500 X-MC-Unique: hTdic4UiM8KsXr3UqlAArw-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 0B8A3100C603; Fri, 22 Jan 2021 16:18:58 +0000 (UTC) Received: from [10.3.113.116] (ovpn-113-116.phx2.redhat.com [10.3.113.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 74E1A5D746; Fri, 22 Jan 2021 16:18:53 +0000 (UTC) Subject: Re: [PATCH v4 10/16] block/io: support int64_t bytes in bdrv_co_do_pwrite_zeroes() To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org References: <20201211183934.169161-1-vsementsov@virtuozzo.com> <20201211183934.169161-11-vsementsov@virtuozzo.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: <3990d2d8-cf2c-96cb-f559-005726112fab@redhat.com> Date: Fri, 22 Jan 2021 10:18:52 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20201211183934.169161-11-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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=216.205.24.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.182, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.221, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=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, berto@igalia.com, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, den@openvz.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 12/11/20 12:39 PM, Vladimir Sementsov-Ogievskiy wrote: > We are generally moving to int64_t for both offset and bytes parameters > on all io paths. > > Main motivation is realization of 64-bit write_zeroes operation for > fast zeroing large disk chunks, up to the whole disk. > > We chose signed type, to be consistent with off_t (which is signed) and > with possibility for signed return type (where negative value means > error). > > So, prepare bdrv_co_do_pwrite_zeroes() now. > > Callers are safe, as converting int to int64_t is safe. Concentrate on > 'bytes' usage in the function (thx to Eric Blake): > > compute 'int tail' via % 'int alignment' - safe > fragmentation loop 'int num' - still fragments with a cap on > max_transfer > > use of 'num' within the loop > MIN(bytes, max_transfer) as well as %alignment - still works, so > calculations in if (head) {} are safe > clamp size by 'int max_write_zeroes' - safe > drv->bdrv_co_pwrite_zeroes(int) - safe because of clamping > clamp size by 'int max_transfer' - safe > buf allocation is still clamped to max_transfer > qemu_iovec_init_buf(size_t) - safe because of clamping > bdrv_driver_pwritev(uint64_t) - safe > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > block/io.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > Reviewed-by: Eric Blake And thanks for including the gist of my previous audit - that greatly speeds things up this time through. ;) -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org