From patchwork Tue Apr 25 17:26:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13223554 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 428C1C6FD18 for ; Tue, 25 Apr 2023 17:27:47 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.526172.817693 (Exim 4.92) (envelope-from ) id 1prMRs-0006fd-9s; Tue, 25 Apr 2023 17:27:28 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 526172.817693; Tue, 25 Apr 2023 17:27:28 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1prMRs-0006fW-78; Tue, 25 Apr 2023 17:27:28 +0000 Received: by outflank-mailman (input) for mailman id 526172; Tue, 25 Apr 2023 17:27:26 +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 1prMRq-0006fQ-Il for xen-devel@lists.xenproject.org; Tue, 25 Apr 2023 17:27:26 +0000 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 70ed4296-e38e-11ed-b223-6b7b168915f2; Tue, 25 Apr 2023 19:27:24 +0200 (CEST) Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-614-L0EAQYIeNnCHTrMEG_ewXg-1; Tue, 25 Apr 2023 13:27:20 -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 559153C0F19B; Tue, 25 Apr 2023 17:27:19 +0000 (UTC) Received: from localhost (unknown [10.39.193.242]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4D29B492B03; Tue, 25 Apr 2023 17:27:18 +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: 70ed4296-e38e-11ed-b223-6b7b168915f2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682443643; 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=f0ej+5pIhrlcIJ/hZlYkQH8FLS/0nkngHI+ORQgtlrE=; b=JlGzrbezcc8mpkqYz782rygcM0vY6jS1dK0S7T99PrgMSOicxs8LUp0ti1jveXbb/Wi54c ESVNJL2peB/YguikIFCePb9lei0ugTxZDr2wXnKyW1H4Evnm7YoLJdF1dRjXHHi3ws2OtX luTKqSSE5ynWmqsXyrfGvw1zyrF3I2g= X-MC-Unique: L0EAQYIeNnCHTrMEG_ewXg-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , Juan Quintela , Julia Suvorova , Kevin Wolf , xen-devel@lists.xenproject.org, eesposit@redhat.com, Richard Henderson , Fam Zheng , "Michael S. Tsirkin" , Coiby Xu , David Woodhouse , Marcel Apfelbaum , Peter Lieven , Paul Durrant , Stefan Hajnoczi , "Richard W.M. Jones" , qemu-block@nongnu.org, Stefano Garzarella , Anthony Perard , Stefan Weil , Xie Yongji , Paolo Bonzini , Aarushi Mehta , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , Eduardo Habkost , Stefano Stabellini , Hanna Reitz , Ronnie Sahlberg Subject: [PATCH v4 00/20] block: remove aio_disable_external() API Date: Tue, 25 Apr 2023 13:26:56 -0400 Message-Id: <20230425172716.1033562-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 v4: - Remove external_disable_cnt variable [Philippe] - Add Patch 1 to fix assertion failure in .drained_end() -> blk_get_aio_context() v3: - Resend full patch series. v2 was sent in the middle of a git rebase and was missing patches. [Eric] - Apply Reviewed-by tags. 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(). Stefan Hajnoczi (20): block-backend: split blk_do_set_aio_context() 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 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 virtio-blk: implement BlockDevOps->drained_begin() virtio-scsi: implement BlockDevOps->drained_begin() virtio: do not set is_external=true on host notifiers aio: remove aio_disable_external() API hw/block/dataplane/xen-block.h | 2 + include/block/aio.h | 57 --------- include/block/export.h | 2 + include/hw/qdev-core.h | 17 ++- include/hw/scsi/scsi.h | 14 +++ include/qemu/vhost-user-server.h | 8 +- include/sysemu/block-backend-common.h | 25 ++-- include/sysemu/block-backend-global-state.h | 1 + util/aio-posix.h | 1 - block.c | 7 -- block/blkio.c | 15 +-- block/block-backend.c | 78 ++++++------ block/curl.c | 10 +- block/export/export.c | 13 +- block/export/fuse.c | 58 ++++++++- block/export/vduse-blk.c | 128 ++++++++++++++------ block/export/vhost-user-blk-server.c | 70 +++++++---- block/io.c | 5 +- block/io_uring.c | 4 +- block/iscsi.c | 3 +- block/linux-aio.c | 4 +- block/nfs.c | 5 +- block/nvme.c | 8 +- block/ssh.c | 4 +- block/win32-aio.c | 6 +- hw/block/dataplane/virtio-blk.c | 19 ++- hw/block/dataplane/xen-block.c | 42 +++++-- hw/block/virtio-blk.c | 38 +++++- hw/block/xen-block.c | 24 +++- hw/i386/kvm/xen_xenstore.c | 2 +- hw/scsi/scsi-bus.c | 46 ++++++- hw/scsi/scsi-disk.c | 28 ++++- hw/scsi/virtio-scsi-dataplane.c | 31 +++-- hw/scsi/virtio-scsi.c | 59 +++++++-- hw/virtio/virtio.c | 6 +- hw/xen/xen-bus.c | 11 +- io/channel-command.c | 6 +- io/channel-file.c | 3 +- io/channel-socket.c | 3 +- migration/rdma.c | 16 +-- tests/unit/test-aio.c | 27 +---- tests/unit/test-bdrv-drain.c | 1 - tests/unit/test-fdmon-epoll.c | 73 ----------- util/aio-posix.c | 20 +-- util/aio-win32.c | 8 +- util/async.c | 3 +- util/fdmon-epoll.c | 18 +-- util/fdmon-io_uring.c | 8 +- util/fdmon-poll.c | 3 +- util/main-loop.c | 7 +- util/qemu-coroutine-io.c | 7 +- util/vhost-user-server.c | 33 ++--- hw/scsi/trace-events | 2 + tests/unit/meson.build | 3 - 54 files changed, 612 insertions(+), 480 deletions(-) delete mode 100644 tests/unit/test-fdmon-epoll.c