From patchwork Mon Apr 16 16:58:43 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 898790 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 40Pvlw0pq5z9s0t for ; Tue, 17 Apr 2018 03:01:00 +1000 (AEST) Received: from localhost ([::1]:58397 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f87Uw-0008Uv-4x for incoming@patchwork.ozlabs.org; Mon, 16 Apr 2018 13:00:58 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60540) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f87TA-0007Ub-BH for qemu-devel@nongnu.org; Mon, 16 Apr 2018 12:59:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f87T9-0003HN-GV for qemu-devel@nongnu.org; Mon, 16 Apr 2018 12:59:08 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50862 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f87T7-0003FC-AN; Mon, 16 Apr 2018 12:59:05 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D0AE14068024; Mon, 16 Apr 2018 16:59:04 +0000 (UTC) Received: from localhost (unknown [10.40.205.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 77F642023227; Mon, 16 Apr 2018 16:59:04 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Mon, 16 Apr 2018 18:58:43 +0200 Message-Id: <20180416165849.28864-4-mreitz@redhat.com> In-Reply-To: <20180416165849.28864-1-mreitz@redhat.com> References: <20180416165849.28864-1-mreitz@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Mon, 16 Apr 2018 16:59:04 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Mon, 16 Apr 2018 16:59:04 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mreitz@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH 3/9] block: Add BDRV_REQ_WRITE_UNCHANGED flag 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: Kevin Wolf , Fam Zheng , qemu-devel@nongnu.org, Stefan Hajnoczi , Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" This flag signifies that a write request will not change the visible disk content. With this flag set, it is sufficient to have the BLK_PERM_WRITE_UNCHANGED permission instead of BLK_PERM_WRITE. Signed-off-by: Max Reitz Reviewed-by: Stefan Hajnoczi Reviewed-by: Alberto Garcia --- include/block/block.h | 6 +++++- block/io.c | 6 +++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/include/block/block.h b/include/block/block.h index 397b5e8d44..3894edda9d 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -54,8 +54,12 @@ typedef enum { BDRV_REQ_FUA = 0x10, BDRV_REQ_WRITE_COMPRESSED = 0x20, + /* Signifies that this write request will not change the visible disk + * content. */ + BDRV_REQ_WRITE_UNCHANGED = 0x40, + /* Mask of valid flags */ - BDRV_REQ_MASK = 0x3f, + BDRV_REQ_MASK = 0x7f, } BdrvRequestFlags; typedef struct BlockSizes { diff --git a/block/io.c b/block/io.c index bd9a19a9c4..134b2a498f 100644 --- a/block/io.c +++ b/block/io.c @@ -1501,7 +1501,11 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child, assert(!waited || !req->serialising); assert(req->overlap_offset <= offset); assert(offset + bytes <= req->overlap_offset + req->overlap_bytes); - assert(child->perm & BLK_PERM_WRITE); + if (flags & BDRV_REQ_WRITE_UNCHANGED) { + assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); + } else { + assert(child->perm & BLK_PERM_WRITE); + } assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE); ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);