From patchwork Tue Nov 7 18:45:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13449211 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 8DC28C4332F for ; Tue, 7 Nov 2023 18:48:18 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r0R6F-0004WM-G1; Tue, 07 Nov 2023 13:46:55 -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 1r0R5p-00041Z-A1 for qemu-devel@nongnu.org; Tue, 07 Nov 2023 13:46:31 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r0R5m-0001WW-V7 for qemu-devel@nongnu.org; Tue, 07 Nov 2023 13:46:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699382783; 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=qA6LD5FvtIcm4HXAg7hKc9KfBeIebVmoNokBPYIOAZw=; b=HcuzCufm5+ExQAWjmnHnF/oPWkpaTB8KYVArlh3Q3lk4ERi78xWp+Q93mC3l+y+Qife/xe VOIwLWTzwupxRdicYtqaP6hNhYF7sthFF4mO0q75mkcRW0tIUz/FpKN5kKUnFX7e6Dz2Xr EUatwIjCajOUG9lI3EB+pFL6bOKGD9g= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-41-9Iqsv_JAP9azlHBbgzYUhQ-1; Tue, 07 Nov 2023 13:46:19 -0500 X-MC-Unique: 9Iqsv_JAP9azlHBbgzYUhQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 082B2185A788 for ; Tue, 7 Nov 2023 18:46:19 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.194.197]) by smtp.corp.redhat.com (Postfix) with ESMTP id 87799C1290F; Tue, 7 Nov 2023 18:46:18 +0000 (UTC) From: Kevin Wolf To: qemu-devel@nongnu.org Cc: kwolf@redhat.com Subject: [PULL 15/25] block: Mark bdrv_replace_node_common() GRAPH_WRLOCK Date: Tue, 7 Nov 2023 19:45:55 +0100 Message-ID: <20231107184605.236540-16-kwolf@redhat.com> In-Reply-To: <20231107184605.236540-1-kwolf@redhat.com> References: <20231107184605.236540-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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 Instead of taking the writer lock internally, require callers to already hold it when calling bdrv_replace_node_common(). Basically everthing in the function needs the lock and its callers may already want to hold the graph lock and so wouldn't be able to call functions that take it internally. Signed-off-by: Kevin Wolf Message-ID: <20231027155333.420094-16-kwolf@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- block.c | 68 ++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 43 insertions(+), 25 deletions(-) diff --git a/block.c b/block.c index dc43e36f69..c7409cf658 100644 --- a/block.c +++ b/block.c @@ -5412,6 +5412,9 @@ bdrv_replace_node_noperm(BlockDriverState *from, } /* + * Switch all parents of @from to point to @to instead. @from and @to must be in + * the same AioContext and both must be drained. + * * With auto_skip=true bdrv_replace_node_common skips updating from parents * if it creates a parent-child relation loop or if parent is block-job. * @@ -5421,10 +5424,9 @@ bdrv_replace_node_noperm(BlockDriverState *from, * With @detach_subchain=true @to must be in a backing chain of @from. In this * case backing link of the cow-parent of @to is removed. */ -static int bdrv_replace_node_common(BlockDriverState *from, - BlockDriverState *to, - bool auto_skip, bool detach_subchain, - Error **errp) +static int GRAPH_WRLOCK +bdrv_replace_node_common(BlockDriverState *from, BlockDriverState *to, + bool auto_skip, bool detach_subchain, Error **errp) { Transaction *tran = tran_new(); g_autoptr(GSList) refresh_list = NULL; @@ -5433,16 +5435,9 @@ static int bdrv_replace_node_common(BlockDriverState *from, GLOBAL_STATE_CODE(); - /* Make sure that @from doesn't go away until we have successfully attached - * all of its parents to @to. */ - bdrv_ref(from); - - assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + assert(from->quiesce_counter); + assert(to->quiesce_counter); assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to)); - bdrv_drained_begin(from); - bdrv_drained_begin(to); - - bdrv_graph_wrlock(to); if (detach_subchain) { assert(bdrv_chain_contains(from, to)); @@ -5483,33 +5478,51 @@ static int bdrv_replace_node_common(BlockDriverState *from, out: tran_finalize(tran, ret); - bdrv_graph_wrunlock(); - - bdrv_drained_end(to); - bdrv_drained_end(from); - bdrv_unref(from); - return ret; } int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, Error **errp) { + int ret; + GLOBAL_STATE_CODE(); - return bdrv_replace_node_common(from, to, true, false, errp); + /* Make sure that @from doesn't go away until we have successfully attached + * all of its parents to @to. */ + bdrv_ref(from); + bdrv_drained_begin(from); + bdrv_drained_begin(to); + bdrv_graph_wrlock(to); + + ret = bdrv_replace_node_common(from, to, true, false, errp); + + bdrv_graph_wrunlock(); + bdrv_drained_end(to); + bdrv_drained_end(from); + bdrv_unref(from); + + return ret; } int bdrv_drop_filter(BlockDriverState *bs, Error **errp) { BlockDriverState *child_bs; + int ret; GLOBAL_STATE_CODE(); + bdrv_graph_rdlock_main_loop(); child_bs = bdrv_filter_or_cow_bs(bs); bdrv_graph_rdunlock_main_loop(); - return bdrv_replace_node_common(bs, child_bs, true, true, errp); + bdrv_drained_begin(child_bs); + bdrv_graph_wrlock(bs); + ret = bdrv_replace_node_common(bs, child_bs, true, true, errp); + bdrv_graph_wrunlock(); + bdrv_drained_end(child_bs); + + return ret; } /* @@ -5957,15 +5970,15 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, bdrv_ref(top); bdrv_drained_begin(base); - bdrv_graph_rdlock_main_loop(); + bdrv_graph_wrlock(base); if (!top->drv || !base->drv) { - goto exit; + goto exit_wrlock; } /* Make sure that base is in the backing chain of top */ if (!bdrv_chain_contains(top, base)) { - goto exit; + goto exit_wrlock; } /* If 'base' recursively inherits from 'top' then we should set @@ -5997,6 +6010,8 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, * That's a FIXME. */ bdrv_replace_node_common(top, base, false, false, &local_err); + bdrv_graph_wrunlock(); + if (local_err) { error_report_err(local_err); goto exit; @@ -6029,8 +6044,11 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, } ret = 0; + goto exit; + +exit_wrlock: + bdrv_graph_wrunlock(); exit: - bdrv_graph_rdunlock_main_loop(); bdrv_drained_end(base); bdrv_unref(top); return ret;