From patchwork Thu Apr 27 01:46:10 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 9702255 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 877D0601D3 for ; Thu, 27 Apr 2017 01:48:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7810D285F8 for ; Thu, 27 Apr 2017 01:48:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6C0C228602; Thu, 27 Apr 2017 01:48:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 12759285F8 for ; Thu, 27 Apr 2017 01:48:03 +0000 (UTC) Received: from localhost ([::1]:57779 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d3YXK-0007Tv-Tw for patchwork-qemu-devel@patchwork.kernel.org; Wed, 26 Apr 2017 21:48:02 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33529) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d3YVx-0007RE-7Q for qemu-devel@nongnu.org; Wed, 26 Apr 2017 21:46:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d3YVw-00042G-Ay for qemu-devel@nongnu.org; Wed, 26 Apr 2017 21:46:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42358) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d3YVr-0003xj-St; Wed, 26 Apr 2017 21:46:32 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id B96D43DBDB; Thu, 27 Apr 2017 01:46:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com B96D43DBDB Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=eblake@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com B96D43DBDB Received: from red.redhat.com (ovpn-123-177.rdu2.redhat.com [10.10.123.177]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0967118114; Thu, 27 Apr 2017 01:46:29 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Date: Wed, 26 Apr 2017 20:46:10 -0500 Message-Id: <20170427014626.11553-2-eblake@redhat.com> In-Reply-To: <20170427014626.11553-1-eblake@redhat.com> References: <20170427014626.11553-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 27 Apr 2017 01:46:30 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v10 01/17] block: Update comments on BDRV_BLOCK_* meanings X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP We had some conflicting documentation: a nice 8-way table that described all possible combinations of DATA, ZERO, and OFFSET_VALID, couple with text that implied that OFFSET_VALID always meant raw data could be read directly. As the 8-way table is the intended semantics, simplify the rest of the text to get rid of the confusion. Suggested-by: Max Reitz Signed-off-by: Eric Blake Reviewed-by: Max Reitz --- v10: new patch --- include/block/block.h | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/include/block/block.h b/include/block/block.h index 862eb56..04fcbd0 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -121,21 +121,22 @@ typedef struct HDGeometry { /* * Allocation status flags - * BDRV_BLOCK_DATA: data is read from a file returned by bdrv_get_block_status. + * BDRV_BLOCK_DATA: data is read from a file returned by bdrv_get_block_status * BDRV_BLOCK_ZERO: sectors read as zero - * BDRV_BLOCK_OFFSET_VALID: sector stored as raw data in a file returned by - * bdrv_get_block_status. + * BDRV_BLOCK_OFFSET_VALID: an associated offset exists for accessing raw data * BDRV_BLOCK_ALLOCATED: the content of the block is determined by this * layer (as opposed to the backing file) * BDRV_BLOCK_RAW: used internally to indicate that the request * was answered by the raw driver and that one * should look in bs->file directly. * - * If BDRV_BLOCK_OFFSET_VALID is set, bits 9-62 represent the offset in - * bs->file where sector data can be read from as raw data. - * * DATA == 0 && ZERO == 0 means that data is read from backing_hd if present. * + * If BDRV_BLOCK_OFFSET_VALID is set, bits 9-62 represent the offset + * in bs->file that is allocated for the corresponding raw data; + * however, whether that offset actually contains data also depends on + * BDRV_BLOCK_DATA, as follows: + * * DATA ZERO OFFSET_VALID * t t t sectors read as zero, bs->file is zero at offset * t f t sectors read as valid from bs->file at offset