From patchwork Tue Sep 1 14:34:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 1355130 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; 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 Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=OSYJ7M5t; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 4Bgqr967MVz9sVw for ; Wed, 2 Sep 2020 00:55:37 +1000 (AEST) Received: from localhost ([::1]:54280 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kD7h9-0006YH-BX for incoming@patchwork.ozlabs.org; Tue, 01 Sep 2020 10:55:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34788) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kD7OD-0001d5-Hs for qemu-devel@nongnu.org; Tue, 01 Sep 2020 10:36:01 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:43595) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kD7O7-0007Sv-RJ for qemu-devel@nongnu.org; Tue, 01 Sep 2020 10:36:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598970955; 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=cQVJgk7gScbmS0jUKqF2Ihq9nAic/LqZNpwybrGbAVw=; b=OSYJ7M5tvybeSHfLLjbH3RK0p9Yx9Jw8lwoIrgBVthWHwV6vIR8XTif3swKKep7d2MVPcN DrEPI5uCM07ExqVGTpoofB5aYl1bK21fjDIG4aGa2M6ofLwPzxqZpOYDMtN54YtapYcztM /2ofsWTeuw0LhqZz408oGfbxXWMG3Qg= 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-187-sB_JusUyMxiy7PxGLyxznA-1; Tue, 01 Sep 2020 10:35:53 -0400 X-MC-Unique: sB_JusUyMxiy7PxGLyxznA-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 2893B10ABDC7; Tue, 1 Sep 2020 14:35:52 +0000 (UTC) Received: from localhost (ovpn-113-83.ams2.redhat.com [10.36.113.83]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6508A1045E83; Tue, 1 Sep 2020 14:35:51 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v8 35/43] blockdev: Fix active commit choice Date: Tue, 1 Sep 2020 16:34:16 +0200 Message-Id: <20200901143424.884735-36-mreitz@redhat.com> In-Reply-To: <20200901143424.884735-1-mreitz@redhat.com> References: <20200901143424.884735-1-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: 0.001 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/01 01:27:29 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=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 , Andrey Shinkevich , Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" We have to perform an active commit whenever the top node has a parent that has taken the WRITE permission on it. This means that block-commit's @backing-file parameter is longer allowed for such nodes, and that users will have to issue a block-job-complete command. Neither should pose a problem in practice, because this case was basically just broken until now. (Since this commit already touches block-commit's documentation, it also moves up the chunk explaining general block-commit behavior that for some reason was situated under @backing-file.) Signed-off-by: Max Reitz --- qapi/block-core.json | 39 ++++++++++++++++++++------------------- blockdev.c | 35 ++++++++++++++++++++++++++++++----- 2 files changed, 50 insertions(+), 24 deletions(-) diff --git a/qapi/block-core.json b/qapi/block-core.json index 8d180b584c..32d4aa0ddc 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -1569,6 +1569,18 @@ # Live commit of data from overlay image nodes into backing nodes - i.e., # writes data between 'top' and 'base' into 'base'. # +# If top == base, that is an error. +# If top has no overlays on top of it, or if it is in use by a writer, +# the job will not be completed by itself. The user needs to complete +# the job with the block-job-complete command after getting the ready +# event. (Since 2.0) +# +# If the base image is smaller than top, then the base image will be +# resized to be the same size as top. If top is smaller than the base +# image, the base will not be truncated. If you want the base image +# size to match the size of the smaller top, you can safely truncate +# it yourself once the commit operation successfully completes. +# # @job-id: identifier for the newly-created block job. If # omitted, the device name will be used. (Since 2.7) # @@ -1593,14 +1605,15 @@ # accepted # # @backing-file: The backing file string to write into the overlay -# image of 'top'. If 'top' is the active layer, -# specifying a backing file string is an error. This -# filename is not validated. +# image of 'top'. If 'top' does not have an overlay +# image, or if 'top' is in use by a writer, specifying +# a backing file string is an error. # -# If a pathname string is such that it cannot be -# resolved by QEMU, that means that subsequent QMP or -# HMP commands must use node-names for the image in -# question, as filename lookup methods will fail. +# This filename is not validated. If a pathname string +# is such that it cannot be resolved by QEMU, that +# means that subsequent QMP or HMP commands must use +# node-names for the image in question, as filename +# lookup methods will fail. # # If not specified, QEMU will automatically determine # the backing file string to use, or error out if @@ -1609,18 +1622,6 @@ # filename or protocol. # (Since 2.1) # -# If top == base, that is an error. -# If top == active, the job will not be completed by itself, -# user needs to complete the job with the block-job-complete -# command after getting the ready event. (Since 2.0) -# -# If the base image is smaller than top, then the base image -# will be resized to be the same size as top. If top is -# smaller than the base image, the base will not be -# truncated. If you want the base image size to match the -# size of the smaller top, you can safely truncate it -# yourself once the commit operation successfully completes. -# # @speed: the maximum speed, in bytes per second # # @on-error: the action to take on an error. 'ignore' means that the request diff --git a/blockdev.c b/blockdev.c index f308adc9aa..7f2561081e 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2602,6 +2602,7 @@ void qmp_block_commit(bool has_job_id, const char *job_id, const char *device, AioContext *aio_context; Error *local_err = NULL; int job_flags = JOB_DEFAULT; + uint64_t top_perm, top_shared; if (!has_speed) { speed = 0; @@ -2717,14 +2718,38 @@ void qmp_block_commit(bool has_job_id, const char *job_id, const char *device, goto out; } - if (top_bs == bs) { + /* + * Active commit is required if and only if someone has taken a + * WRITE permission on the top node. Historically, we have always + * used active commit for top nodes, so continue that practice + * lest we possibly break clients that rely on this behavior, e.g. + * to later attach this node to a writing parent. + * (Active commit is never really wrong.) + */ + bdrv_get_cumulative_perm(top_bs, &top_perm, &top_shared); + if (top_perm & BLK_PERM_WRITE || + bdrv_skip_filters(top_bs) == bdrv_skip_filters(bs)) + { if (has_backing_file) { - error_setg(errp, "'backing-file' specified," - " but 'top' is the active layer"); + if (bdrv_skip_filters(top_bs) == bdrv_skip_filters(bs)) { + error_setg(errp, "'backing-file' specified," + " but 'top' is the active layer"); + } else { + error_setg(errp, "'backing-file' specified, but 'top' has a " + "writer on it"); + } goto out; } - commit_active_start(has_job_id ? job_id : NULL, bs, base_bs, - job_flags, speed, on_error, + if (!has_job_id) { + /* + * Emulate here what block_job_create() does, because it + * is possible that @bs != @top_bs (the block job should + * be named after @bs, even if @top_bs is the actual + * source) + */ + job_id = bdrv_get_device_name(bs); + } + commit_active_start(job_id, top_bs, base_bs, job_flags, speed, on_error, filter_node_name, NULL, NULL, false, &local_err); } else { BlockDriverState *overlay_bs = bdrv_find_overlay(bs, top_bs);