From patchwork Thu May 4 11:57:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13231111 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 F417DC77B78 for ; Thu, 4 May 2023 11:59:40 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1puXbU-0003Mg-34; Thu, 04 May 2023 07:58:32 -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 1puXbG-0003Ag-4W for qemu-devel@nongnu.org; Thu, 04 May 2023 07:58:18 -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 1puXbD-0004DZ-NK for qemu-devel@nongnu.org; Thu, 04 May 2023 07:58:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1683201494; 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=tU7ahHCz+W2gnqL9QeXCpZJM9olRFNuNP87npfPIqOg=; b=IfQluCE790rOSRC8uUpMzSSJdPF9bAWxvyxo0FsUV5gCyQ3O+x8gVTEO69kNVtUVq6Pm4M BU6FvmkUO2k+VC+mYgriZo5gyMVCc4upD54OvRnaCZSmvN9aa8vpPkbzTuw2qEPcvB+lCc gyHINAQObWu0D5kTAddJ9iDvJkOTbUY= 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-176-ScPiV8MeNUSf3a6EK2HnKg-1; Thu, 04 May 2023 07:58:11 -0400 X-MC-Unique: ScPiV8MeNUSf3a6EK2HnKg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 59889101A531; Thu, 4 May 2023 11:58:11 +0000 (UTC) Received: from merkur.redhat.com (unknown [10.39.194.84]) by smtp.corp.redhat.com (Postfix) with ESMTP id 298BBC15BAD; Thu, 4 May 2023 11:58:10 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, eblake@redhat.com, eesposit@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org Subject: [PATCH v2 08/20] block: .bdrv_open is non-coroutine and unlocked Date: Thu, 4 May 2023 13:57:38 +0200 Message-Id: <20230504115750.54437-9-kwolf@redhat.com> In-Reply-To: <20230504115750.54437-1-kwolf@redhat.com> References: <20230504115750.54437-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 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: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.161, 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_H2=-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 Drivers were a bit confused about whether .bdrv_open can run in a coroutine and whether or not it holds a graph lock. It cannot keep a graph lock from the caller across the whole function because it both changes the graph (requires a writer lock) and does I/O (requires a reader lock). Therefore, it should take these locks internally as needed. The functions used to be called in coroutine context during image creation. This was buggy for other reasons, and as of commit 32192301, all block drivers go through no_co_wrappers. So it is not called in coroutine context any more. Fix qcow2 and qed to work with the correct assumptions: The graph lock needs to be taken internally instead of just assuming it's already there, and the coroutine path is dead code that can be removed. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi --- include/block/block_int-common.h | 8 ++++---- block.c | 6 +++--- block/qcow2.c | 15 ++++++--------- block/qed.c | 18 ++++++++---------- 4 files changed, 21 insertions(+), 26 deletions(-) diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 013d419444..6fb28cd8fa 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -236,12 +236,12 @@ struct BlockDriver { void (*bdrv_reopen_abort)(BDRVReopenState *reopen_state); void (*bdrv_join_options)(QDict *options, QDict *old_options); - int (*bdrv_open)(BlockDriverState *bs, QDict *options, int flags, - Error **errp); + int GRAPH_UNLOCKED_PTR (*bdrv_open)( + BlockDriverState *bs, QDict *options, int flags, Error **errp); /* Protocol drivers should implement this instead of bdrv_open */ - int (*bdrv_file_open)(BlockDriverState *bs, QDict *options, int flags, - Error **errp); + int GRAPH_UNLOCKED_PTR (*bdrv_file_open)( + BlockDriverState *bs, QDict *options, int flags, Error **errp); void (*bdrv_close)(BlockDriverState *bs); int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_create)( diff --git a/block.c b/block.c index 20d5ee0959..abec940867 100644 --- a/block.c +++ b/block.c @@ -1610,9 +1610,9 @@ out: * bdrv_refresh_total_sectors() which polls when called from non-coroutine * context. */ -static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, - const char *node_name, QDict *options, - int open_flags, Error **errp) +static int no_coroutine_fn GRAPH_UNLOCKED +bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name, + QDict *options, int open_flags, Error **errp) { Error *local_err = NULL; int i, ret; diff --git a/block/qcow2.c b/block/qcow2.c index 01742b3ebe..5bde3b8401 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1891,7 +1891,7 @@ static void coroutine_fn qcow2_open_entry(void *opaque) QCow2OpenCo *qoc = opaque; BDRVQcow2State *s = qoc->bs->opaque; - assume_graph_lock(); /* FIXME */ + GRAPH_RDLOCK_GUARD(); qemu_co_mutex_lock(&s->lock); qoc->ret = qcow2_do_open(qoc->bs, qoc->options, qoc->flags, true, @@ -1920,14 +1920,11 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, /* Initialise locks */ qemu_co_mutex_init(&s->lock); - if (qemu_in_coroutine()) { - /* From bdrv_co_create. */ - qcow2_open_entry(&qoc); - } else { - assert(qemu_get_current_aio_context() == qemu_get_aio_context()); - qemu_coroutine_enter(qemu_coroutine_create(qcow2_open_entry, &qoc)); - BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS); - } + assert(!qemu_in_coroutine()); + assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + qemu_coroutine_enter(qemu_coroutine_create(qcow2_open_entry, &qoc)); + BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS); + return qoc.ret; } diff --git a/block/qed.c b/block/qed.c index aff2a2076e..be9ff0fb34 100644 --- a/block/qed.c +++ b/block/qed.c @@ -557,11 +557,13 @@ typedef struct QEDOpenCo { int ret; } QEDOpenCo; -static void coroutine_fn GRAPH_RDLOCK bdrv_qed_open_entry(void *opaque) +static void coroutine_fn bdrv_qed_open_entry(void *opaque) { QEDOpenCo *qoc = opaque; BDRVQEDState *s = qoc->bs->opaque; + GRAPH_RDLOCK_GUARD(); + qemu_co_mutex_lock(&s->table_lock); qoc->ret = bdrv_qed_do_open(qoc->bs, qoc->options, qoc->flags, qoc->errp); qemu_co_mutex_unlock(&s->table_lock); @@ -579,21 +581,17 @@ static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags, }; int ret; - assume_graph_lock(); /* FIXME */ - ret = bdrv_open_file_child(NULL, options, "file", bs, errp); if (ret < 0) { return ret; } bdrv_qed_init_state(bs); - if (qemu_in_coroutine()) { - bdrv_qed_open_entry(&qoc); - } else { - assert(qemu_get_current_aio_context() == qemu_get_aio_context()); - qemu_coroutine_enter(qemu_coroutine_create(bdrv_qed_open_entry, &qoc)); - BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS); - } + assert(!qemu_in_coroutine()); + assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + qemu_coroutine_enter(qemu_coroutine_create(bdrv_qed_open_entry, &qoc)); + BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS); + return qoc.ret; }