From patchwork Wed Apr 19 17:28:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13217193 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.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 4BBA1C6FD18 for ; Wed, 19 Apr 2023 17:28:56 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.523640.813879 (Exim 4.92) (envelope-from ) id 1ppBbb-0001in-95; Wed, 19 Apr 2023 17:28:31 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 523640.813879; Wed, 19 Apr 2023 17:28:31 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ppBbb-0001ig-66; Wed, 19 Apr 2023 17:28:31 +0000 Received: by outflank-mailman (input) for mailman id 523640; Wed, 19 Apr 2023 17:28:30 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ppBba-0001ia-M1 for xen-devel@lists.xenproject.org; Wed, 19 Apr 2023 17:28:30 +0000 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 985f871d-ded7-11ed-b21f-6b7b168915f2; Wed, 19 Apr 2023 19:28:28 +0200 (CEST) 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-637-61a8q54tM8SArQfWECWbMQ-1; Wed, 19 Apr 2023 13:28:22 -0400 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CF33185C069; Wed, 19 Apr 2023 17:28:20 +0000 (UTC) Received: from localhost (unknown [10.39.192.234]) by smtp.corp.redhat.com (Postfix) with ESMTP id 65E3C483EC4; Wed, 19 Apr 2023 17:28:19 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 985f871d-ded7-11ed-b21f-6b7b168915f2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681925307; 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=JAqVXMqjwf5xGB6ARdoAeUgfvsknmkfSYSzm+VSDhMc=; b=B/gffyY6tWv2BCXraGKpu2rn5Fy+0sL3j0wosTVDP7L4lg5wFOmT8bf3qog7y3en4Qcg3k JDOIBGCNx0/mxxnB9HHBCnzAH/3jWvA42caQyOlAaNzHyw/2CAtZWAF1DixhnxAcSbjIvu jDtpAIZMsaf9Gb15G0Q+ZZQFG/CP7RY= X-MC-Unique: 61a8q54tM8SArQfWECWbMQ-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Stefano Stabellini , Marcel Apfelbaum , Fam Zheng , Stefan Hajnoczi , Julia Suvorova , Hanna Reitz , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , Paolo Bonzini , Coiby Xu , Paul Durrant , Ronnie Sahlberg , Eduardo Habkost , Juan Quintela , "Michael S. Tsirkin" , Stefano Garzarella , Anthony Perard , Kevin Wolf , "Richard W.M. Jones" , Richard Henderson , xen-devel@lists.xenproject.org, qemu-block@nongnu.org, "Dr. David Alan Gilbert" , =?utf-8?q?Philippe_Mathieu-?= =?utf-8?q?Daud=C3=A9?= , Peter Lieven , eesposit@redhat.com, Aarushi Mehta , Stefan Weil , Xie Yongji , David Woodhouse Subject: [PATCH v2 00/16] block: remove aio_disable_external() API Date: Wed, 19 Apr 2023 13:28:01 -0400 Message-Id: <20230419172817.272758-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 v2: - Do not rely on BlockBackend request queuing, implement .drained_begin/end() instead in xen-block, virtio-blk, and virtio-scsi [Paolo] - Add qdev_is_realized() API [Philippe] - Add patch to avoid AioContext lock around blk_exp_ref/unref() [Paolo] - Add patch to call .drained_begin/end() from main loop thread to simplify callback implementations The aio_disable_external() API temporarily suspends file descriptor monitoring in the event loop. The block layer uses this to prevent new I/O requests being submitted from the guest and elsewhere between bdrv_drained_begin() and bdrv_drained_end(). While the block layer still needs to prevent new I/O requests in drained sections, the aio_disable_external() API can be replaced with .drained_begin/end/poll() callbacks that have been added to BdrvChildClass and BlockDevOps. This newer .bdrained_begin/end/poll() approach is attractive because it works without specifying a specific AioContext. The block layer is moving towards multi-queue and that means multiple AioContexts may be processing I/O simultaneously. The aio_disable_external() was always somewhat hacky. It suspends all file descriptors that were registered with is_external=true, even if they have nothing to do with the BlockDriverState graph nodes that are being drained. It's better to solve a block layer problem in the block layer than to have an odd event loop API solution. The approach in this patch series is to implement BlockDevOps .drained_begin/end() callbacks that temporarily stop file descriptor handlers. This ensures that new I/O requests are not submitted in drained sections. The first two virtio-scsi patches were already sent as a separate series. I included them because they are necessary in order to fully remove aio_disable_external(). Based-on: 087bc644b7634436ca9d52fe58ba9234e2bef026 (kevin/block-next) Stefan Hajnoczi (16): hw/qdev: introduce qdev_is_realized() helper virtio-scsi: avoid race between unplug and transport event virtio-scsi: stop using aio_disable_external() during unplug block/export: only acquire AioContext once for vhost_user_server_stop() util/vhost-user-server: rename refcount to in_flight counter block/export: wait for vhost-user-blk requests when draining block/export: stop using is_external in vhost-user-blk server hw/xen: do not use aio_set_fd_handler(is_external=true) in xen_xenstore block: add blk_in_drain() API block: drain from main loop thread in bdrv_co_yield_to_drain() xen-block: implement BlockDevOps->drained_begin() hw/xen: do not set is_external=true on evtchn fds block/export: rewrite vduse-blk drain code block/export: don't require AioContext lock around blk_exp_ref/unref() block/fuse: do not set is_external=true on FUSE fd virtio: make it possible to detach host notifier from any thread hw/block/dataplane/xen-block.h | 2 + include/block/export.h | 2 + include/hw/qdev-core.h | 17 ++- include/qemu/vhost-user-server.h | 8 +- include/sysemu/block-backend-common.h | 25 ++-- include/sysemu/block-backend-global-state.h | 1 + block/block-backend.c | 7 ++ block/export/export.c | 13 +- block/export/fuse.c | 58 ++++++++- block/export/vduse-blk.c | 128 ++++++++++++++------ block/export/vhost-user-blk-server.c | 73 +++++++---- block/io.c | 3 +- hw/block/dataplane/virtio-blk.c | 2 + hw/block/dataplane/xen-block.c | 42 +++++-- hw/block/xen-block.c | 24 +++- hw/i386/kvm/xen_xenstore.c | 2 +- hw/scsi/scsi-bus.c | 6 +- hw/scsi/scsi-disk.c | 1 + hw/scsi/virtio-scsi-dataplane.c | 9 ++ hw/scsi/virtio-scsi.c | 21 ++-- hw/xen/xen-bus.c | 11 +- util/vhost-user-server.c | 37 +++--- 22 files changed, 348 insertions(+), 144 deletions(-)