From patchwork Wed Apr 29 14:11:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 283783 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=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 28BCEC83004 for ; Wed, 29 Apr 2020 14:12:58 +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 E5D512083B for ; Wed, 29 Apr 2020 14:12:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XVPEc3ni" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E5D512083B 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]:45386 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jTnSL-00069x-2K for qemu-devel@archiver.kernel.org; Wed, 29 Apr 2020 10:12:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44560) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jTnR9-0004EV-HH for qemu-devel@nongnu.org; Wed, 29 Apr 2020 10:11:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.90_1) (envelope-from ) id 1jTnR7-0003oX-Rn for qemu-devel@nongnu.org; Wed, 29 Apr 2020 10:11:43 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:47129 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jTnR7-0003nk-C7 for qemu-devel@nongnu.org; Wed, 29 Apr 2020 10:11:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588169500; 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=FQKFlGPfdHV/T7NfahVMwoaWj+cSCQ1SVe+ijrXL3rg=; b=XVPEc3nikVDduR09PvJntAbYq75FwyZaUwSxPWlH1XzDLr9rOl54+hEOsJF6UDwMIpTtzd MT9E4XaoRTuXoc78WL4sGz0sO1A7UuV17G2fJ7HZWTDIVt6o5aaZoIuebxV1wdJoWKY7cS rA7z7lNxMjP0fIyd3U6V7XjhIX2Aptc= 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-96-rRQztMSCNl-09LJIAtdX2g-1; Wed, 29 Apr 2020 10:11:38 -0400 X-MC-Unique: rRQztMSCNl-09LJIAtdX2g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5AAF918FE894; Wed, 29 Apr 2020 14:11:30 +0000 (UTC) Received: from localhost (ovpn-113-19.ams2.redhat.com [10.36.113.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EC60A1E4; Wed, 29 Apr 2020 14:11:29 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v2 1/4] block: Add bdrv_make_empty() Date: Wed, 29 Apr 2020 16:11:23 +0200 Message-Id: <20200429141126.85159-2-mreitz@redhat.com> In-Reply-To: <20200429141126.85159-1-mreitz@redhat.com> References: <20200429141126.85159-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.120; envelope-from=mreitz@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/29 01:42:37 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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 , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Right now, all users of bdrv_make_empty() call the BlockDriver method directly. That is not only bad style, it is also wrong, unless the caller has a BdrvChild with a WRITE or WRITE_UNCHANGED permission. (WRITE_UNCHANGED suffices, because callers generally use this function to clear a node with a backing file after a commit operation.) Introduce bdrv_make_empty() that verifies that it does. Signed-off-by: Max Reitz --- include/block/block.h | 1 + block.c | 23 +++++++++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/include/block/block.h b/include/block/block.h index 8b62429aa4..1dee50419c 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -352,6 +352,7 @@ BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr); void bdrv_refresh_limits(BlockDriverState *bs, Error **errp); int bdrv_commit(BlockDriverState *bs); +int bdrv_make_empty(BdrvChild *c, Error **errp); int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file, const char *backing_fmt); void bdrv_register(BlockDriver *bdrv); diff --git a/block.c b/block.c index 03cc5813a2..d6580db0e2 100644 --- a/block.c +++ b/block.c @@ -6792,3 +6792,26 @@ void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) parent_bs->drv->bdrv_del_child(parent_bs, child, errp); } + +int bdrv_make_empty(BdrvChild *c, Error **errp) +{ + BlockDriver *drv = c->bs->drv; + int ret; + + assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)); + + if (!drv->bdrv_make_empty) { + error_setg(errp, "%s does not support emptying nodes", + drv->format_name); + return -ENOTSUP; + } + + ret = drv->bdrv_make_empty(c->bs); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to empty %s", + c->bs->filename); + return ret; + } + + return 0; +}