From patchwork Mon Nov 7 15:13:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 13034561 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 57631C433FE for ; Mon, 7 Nov 2022 15:15:05 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1os3ob-0001qg-4O; Mon, 07 Nov 2022 10:13:33 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1os3oZ-0001pd-4e for qemu-devel@nongnu.org; Mon, 07 Nov 2022 10:13:31 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1os3oW-0006V5-3W for qemu-devel@nongnu.org; Mon, 07 Nov 2022 10:13:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667834006; 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; bh=386KRe582invMrg1CFWPn+IzjN5j2vIQJrD792OEshM=; b=Fv4HqIdrohskZQbeJpY5K//x6O6OG20RfuDK06lNH1tKkCNHQqZu5YfhJw0oEEFXrcA8a3 zH9jbreJpmQFoQ9lfSku0+Wz9oBK/ZYnmd/vsGkAJpGH30SRt7RSWsynn4tZ0n6tHQ50vv csLUZXitNlm/7UavH4Ln5lm+WNh3IGU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-112-b3XN0VqNO46s-uW2rjrCYg-1; Mon, 07 Nov 2022 10:13:23 -0500 X-MC-Unique: b3XN0VqNO46s-uW2rjrCYg-1 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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6F9E3185A7A9; Mon, 7 Nov 2022 15:13:23 +0000 (UTC) Received: from localhost (unknown [10.39.194.227]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1AD142028DC1; Mon, 7 Nov 2022 15:13:22 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Hanna Reitz , Kevin Wolf , Stefan Hajnoczi Subject: [PATCH v2 0/3] block: Start/end drain on correct AioContext Date: Mon, 7 Nov 2022 16:13:18 +0100 Message-Id: <20221107151321.211175-1-hreitz@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, PP_MIME_FAKE_ASCII_TEXT=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi, v1 cover letter: https://lists.nongnu.org/archive/html/qemu-block/2022-09/msg00389.html bdrv_replace_child_noperm() drains the child via bdrv_parent_drained_{begin,end}_single(). When it removes a child, the bdrv_parent_drained_end_single() at its end will be called on an empty child, making the BDRV_POLL_WHILE() in it poll the main AioContext (because c->bs is NULL). That’s wrong, though, because it’s supposed to operate on the parent. bdrv_parent_drained_end_single_no_poll() will have scheduled any BHs in the parents’ AioContext, which may be anything, not necessarily the main context. Therefore, we must poll the parent’s context. Patch 3 does this for both bdrv_parent_drained_{begin,end}_single(). Patch 1 ensures that we can legally call bdrv_child_get_parent_aio_context() from those I/O context functions, and patch 2 fixes blk_do_set_aio_context() to not cause an assertion failure if it beginning a drain can end up in blk_get_aio_context() before blk->ctx has been updated. v2: - Patch 1: - Move bdrv_child_get_parent_aio_context() from block-global-state.h to block-io.h - Move BdrvChildClass.get_parent_aio_context into the I/O code section - Mark blk_root_get_parent_aio_context() as I/O code - Mark child_job_get_parent_aio_context(), and lock the job mutex, which we now need to do (as of 3ed4f708fe1) - Patch 2: - Added comment similar to Kevin’s suggestion (Still decided to take Kevin’s R-b, even though I didn’t use the literal suggestion, but made it a bit more verbose) Hanna Reitz (3): block: Make bdrv_child_get_parent_aio_context I/O block-backend: Update ctx immediately after root block: Start/end drain on correct AioContext include/block/block-global-state.h | 1 - include/block/block-io.h | 2 ++ include/block/block_int-common.h | 4 ++-- block.c | 2 +- block/block-backend.c | 9 ++++++++- block/io.c | 6 ++++-- blockjob.c | 3 ++- 7 files changed, 19 insertions(+), 8 deletions(-)