From mboxrd@z Thu Jan 1 00:00:00 1970 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 BBF71C5B549 for ; Wed, 4 Jun 2025 18:06:52 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uMsVP-0000JG-BV; Wed, 04 Jun 2025 14:06:28 -0400 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 1uMsV4-0000DW-2L for qemu-devel@nongnu.org; Wed, 04 Jun 2025 14:06:08 -0400 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 1uMsV2-00025Y-4r for qemu-devel@nongnu.org; Wed, 04 Jun 2025 14:06:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749060361; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ja41yrXMXkxb9nyZhS+Klic+i89IEtaNdZx/kY7uJGM=; b=Abr6ey2JdsF9eIBpEqy/16BiX1UD0XaSsJIEMzifaZWI3GI+7GfOiCdP/TvR/2bjRBYJsB 1m8FSPKsl4sGFne/aoGp+9+dj7tghrAeHMh/fh0Z36q9L6KpEOuG0cPsvRXYckMdUisYXN 8URceUhhk+mg0El4+WQpMoP+PIin1t0= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-441-QhcRrrNhPXCXUCBlxJgL_Q-1; Wed, 04 Jun 2025 13:56:45 -0400 X-MC-Unique: QhcRrrNhPXCXUCBlxJgL_Q-1 X-Mimecast-MFC-AGG-ID: QhcRrrNhPXCXUCBlxJgL_Q_1749059805 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D9D7B1955D69; Wed, 4 Jun 2025 17:56:44 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.44.34.43]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 93C7018002B3; Wed, 4 Jun 2025 17:56:43 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 14/24] block: move drain outside of quorum_add_child() Date: Wed, 4 Jun 2025 19:56:03 +0200 Message-ID: <20250604175613.344113-15-kwolf@redhat.com> In-Reply-To: <20250604175613.344113-1-kwolf@redhat.com> References: <20250604175613.344113-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.128, 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, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=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 From: Fiona Ebner This is part of resolving the deadlock mentioned in commit "block: move draining out of bdrv_change_aio_context() and mark GRAPH_RDLOCK". The quorum_add_child() callback runs under the graph lock, so it is not allowed to drain. It is only called as the .bdrv_add_child() callback, which is only called in the bdrv_add_child() function, which also runs under the graph lock. The bdrv_add_child() function is called by qmp_x_blockdev_change(), where a drained section is introduced. Signed-off-by: Fiona Ebner Message-ID: <20250530151125.955508-15-f.ebner@proxmox.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- include/block/block_int-common.h | 7 +++++++ block.c | 10 ++++++++-- block/quorum.c | 2 -- blockdev.c | 2 ++ 4 files changed, 17 insertions(+), 4 deletions(-) diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 168f703fa1..f9e742f812 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -396,6 +396,13 @@ struct BlockDriver { int GRAPH_RDLOCK_PTR (*bdrv_probe_geometry)( BlockDriverState *bs, HDGeometry *geo); + /** + * Hot add a BDS's child. Used in combination with bdrv_del_child, so the + * user can take a child offline when it is broken and take a new child + * online. + * + * All block nodes must be drained. + */ void GRAPH_WRLOCK_PTR (*bdrv_add_child)( BlockDriverState *parent, BlockDriverState *child, Error **errp); diff --git a/block.c b/block.c index 6fc87aa318..f6c2f7e208 100644 --- a/block.c +++ b/block.c @@ -8220,8 +8220,10 @@ char *bdrv_dirname(BlockDriverState *bs, Error **errp) } /* - * Hot add/remove a BDS's child. So the user can take a child offline when - * it is broken and take a new child online + * Hot add a BDS's child. Used in combination with bdrv_del_child, so the user + * can take a child offline when it is broken and take a new child online. + * + * All block nodes must be drained. */ void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, Error **errp) @@ -8261,6 +8263,10 @@ void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp); } +/* + * Hot remove a BDS's child. Used in combination with bdrv_add_child, so the + * user can take a child offline when it is broken and take a new child online. + */ void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) { BdrvChild *tmp; diff --git a/block/quorum.c b/block/quorum.c index ea17b0ec13..ed8ce801ee 100644 --- a/block/quorum.c +++ b/block/quorum.c @@ -1096,10 +1096,8 @@ quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs, Error **errp) /* We can safely add the child now */ bdrv_ref(child_bs); - bdrv_drain_all_begin(); child = bdrv_attach_child(bs, child_bs, indexstr, &child_of_bds, BDRV_CHILD_DATA, errp); - bdrv_drain_all_end(); if (child == NULL) { s->next_child_index--; return; diff --git a/blockdev.c b/blockdev.c index 750beba41f..bd5ca77619 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3531,6 +3531,7 @@ void qmp_x_blockdev_change(const char *parent, const char *child, BlockDriverState *parent_bs, *new_bs = NULL; BdrvChild *p_child; + bdrv_drain_all_begin(); bdrv_graph_wrlock(); parent_bs = bdrv_lookup_bs(parent, parent, errp); @@ -3568,6 +3569,7 @@ void qmp_x_blockdev_change(const char *parent, const char *child, out: bdrv_graph_wrunlock(); + bdrv_drain_all_end(); } BlockJobInfoList *qmp_query_block_jobs(Error **errp) -- 2.49.0