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 10293C5B543 for ; Wed, 4 Jun 2025 17:58:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uMsMP-0002Vg-5R; Wed, 04 Jun 2025 13:57:09 -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 1uMsM9-0002HT-J6 for qemu-devel@nongnu.org; Wed, 04 Jun 2025 13:56:53 -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 1uMsM3-0000Rn-U7 for qemu-devel@nongnu.org; Wed, 04 Jun 2025 13:56:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749059801; 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=/FnJpx3hRFEtB4K7jN5OTsYYruyCSn2oaUnCHJa+wlI=; b=QmRWXJlyH7fI64jvZ/ub71uD1prc9QE624bJYfUGau1VzbW3BTjc8maEU73n3hrPTCDCm/ 4kSYyTisgoY378r1D1p/WkGfFmQ9FEIGpwPIVP/WV3+FuH/eXZAJ+0XfY37CKyo9ajf6W3 Nj8HDYGnRZ39EgWm3Y/Y81N23NWLhDI= Received: from mx-prod-mc-03.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-624-h6fCX4CpO-ONcz60HiLEsg-1; Wed, 04 Jun 2025 13:56:40 -0400 X-MC-Unique: h6fCX4CpO-ONcz60HiLEsg-1 X-Mimecast-MFC-AGG-ID: h6fCX4CpO-ONcz60HiLEsg_1749059799 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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7F6D719560B7; Wed, 4 Jun 2025 17:56:39 +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 38A9218002A5; Wed, 4 Jun 2025 17:56:37 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 11/24] block: move drain outside of bdrv_set_backing_hd_drained() Date: Wed, 4 Jun 2025 19:56:00 +0200 Message-ID: <20250604175613.344113-12-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 function bdrv_set_backing_hd_drained() holds the graph lock, so it is not allowed to drain. It is called by: 1. bdrv_set_backing_hd(), where a drained section is introduced, replacing the previously present bs-specific drains. 2. stream_prepare(), where a drained section is introduced replacing the previously present bs-specific drains. The drain_bs variable in bdrv_set_backing_hd_drained() is now superfluous and thus dropped. Signed-off-by: Fiona Ebner Message-ID: <20250530151125.955508-12-f.ebner@proxmox.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block.c | 16 +++------------- block/stream.c | 6 ++---- 2 files changed, 5 insertions(+), 17 deletions(-) diff --git a/block.c b/block.c index 46eb2fe449..e53a88e1b6 100644 --- a/block.c +++ b/block.c @@ -3562,8 +3562,7 @@ out: * Both @bs and @backing_hd can move to a different AioContext in this * function. * - * If a backing child is already present (i.e. we're detaching a node), that - * child node must be drained. + * All block nodes must be drained. */ int bdrv_set_backing_hd_drained(BlockDriverState *bs, BlockDriverState *backing_hd, @@ -3578,7 +3577,6 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs, assert(bs->backing->bs->quiesce_counter > 0); } - bdrv_drain_all_begin(); ret = bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp); if (ret < 0) { goto out; @@ -3587,28 +3585,20 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs, ret = bdrv_refresh_perms(bs, tran, errp); out: tran_finalize(tran, ret); - bdrv_drain_all_end(); return ret; } int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, Error **errp) { - BlockDriverState *drain_bs; int ret; GLOBAL_STATE_CODE(); - bdrv_graph_rdlock_main_loop(); - drain_bs = bs->backing ? bs->backing->bs : bs; - bdrv_graph_rdunlock_main_loop(); - - bdrv_ref(drain_bs); - bdrv_drained_begin(drain_bs); + bdrv_drain_all_begin(); bdrv_graph_wrlock(); ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp); bdrv_graph_wrunlock(); - bdrv_drained_end(drain_bs); - bdrv_unref(drain_bs); + bdrv_drain_all_end(); return ret; } diff --git a/block/stream.c b/block/stream.c index 999d9e56d4..6ba49cffd3 100644 --- a/block/stream.c +++ b/block/stream.c @@ -80,11 +80,10 @@ static int stream_prepare(Job *job) * may end up working with the wrong base node (or it might even have gone * away by the time we want to use it). */ - bdrv_drained_begin(unfiltered_bs); if (unfiltered_bs_cow) { bdrv_ref(unfiltered_bs_cow); - bdrv_drained_begin(unfiltered_bs_cow); } + bdrv_drain_all_begin(); bdrv_graph_rdlock_main_loop(); base = bdrv_filter_or_cow_bs(s->above_base); @@ -123,11 +122,10 @@ static int stream_prepare(Job *job) } out: + bdrv_drain_all_end(); if (unfiltered_bs_cow) { - bdrv_drained_end(unfiltered_bs_cow); bdrv_unref(unfiltered_bs_cow); } - bdrv_drained_end(unfiltered_bs); return ret; } -- 2.49.0