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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 524C3C48BC2 for ; Wed, 23 Jun 2021 15:03:47 +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 133CA6101D for ; Wed, 23 Jun 2021 15:03:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 133CA6101D 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]:58546 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lw4Pq-0008Gq-38 for qemu-devel@archiver.kernel.org; Wed, 23 Jun 2021 11:03:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56124) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lw4O8-0004om-52 for qemu-devel@nongnu.org; Wed, 23 Jun 2021 11:02:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:57543) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lw4O6-0004m3-5M for qemu-devel@nongnu.org; Wed, 23 Jun 2021 11:01:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624460517; 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=Egj7iDznbXv1swyJTjX1OYn4yl6Dt2WIO3tRfvdXgXw=; b=L2xvWlSC6Xyx0v/1eOWHKxlNnlJB5NCSrHs9S2Efsq9hN9LSF2dBncoZb6jZAUjMZarSe5 WrQTwWye5oyShUTNNWUgAeeToVUzVM8P/tSztPrRl+IkA7by5TiGRexqyOAGF+6izzQgTm xrGs1b/LGJeLLHizBaHksTymOKq1R7c= 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-435-uYZOC0grNkibQ2n6CVH6Vg-1; Wed, 23 Jun 2021 11:01:53 -0400 X-MC-Unique: uYZOC0grNkibQ2n6CVH6Vg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 81ECE1084F75; Wed, 23 Jun 2021 15:01:52 +0000 (UTC) Received: from localhost (ovpn-113-73.ams2.redhat.com [10.36.113.73]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2331A10016F8; Wed, 23 Jun 2021 15:01:51 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v2 3/6] block: Clarify that @bytes is no limit on *pnum Date: Wed, 23 Jun 2021 17:01:40 +0200 Message-Id: <20210623150143.188184-4-mreitz@redhat.com> In-Reply-To: <20210623150143.188184-1-mreitz@redhat.com> References: <20210623150143.188184-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@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=-0.373, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Kevin Wolf , Vladimir Sementsov-Ogievskiy , Eric Blake , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" .bdrv_co_block_status() implementations are free to return a *pnum that exceeds @bytes, because bdrv_co_block_status() in block/io.c will clamp *pnum as necessary. On the other hand, if drivers' implementations return values for *pnum that are as large as possible, our recently introduced block-status cache will become more effective. So, make a note in block_int.h that @bytes is no upper limit for *pnum. Suggested-by: Eric Blake Signed-off-by: Max Reitz --- include/block/block_int.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/include/block/block_int.h b/include/block/block_int.h index fcb599dd1c..f85b96ed99 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -347,6 +347,11 @@ struct BlockDriver { * clamped to bdrv_getlength() and aligned to request_alignment, * as well as non-NULL pnum, map, and file; in turn, the driver * must return an error or set pnum to an aligned non-zero value. + * + * Note that @bytes is just a hint on how big of a region the + * caller wants to inspect. It is not a limit on *pnum. + * Implementations are free to return larger values of *pnum if + * doing so does not incur a performance penalty. */ int coroutine_fn (*bdrv_co_block_status)(BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum, -- 2.31.1