From patchwork Wed Feb 16 10:53:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12748416 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 C0FDBC433F5 for ; Wed, 16 Feb 2022 10:55:39 +0000 (UTC) Received: from localhost ([::1]:36480 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nKHyE-0000gv-Hm for qemu-devel@archiver.kernel.org; Wed, 16 Feb 2022 05:55:38 -0500 Received: from eggs.gnu.org ([209.51.188.92]:52328) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKHwm-0006kf-TS for qemu-devel@nongnu.org; Wed, 16 Feb 2022 05:54:08 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:42829) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKHwk-0001mX-PM for qemu-devel@nongnu.org; Wed, 16 Feb 2022 05:54:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645008846; 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: in-reply-to:in-reply-to:references:references; bh=QUipPV/WQD0j8Bw7+uWNEGnNDcZt5kXpRo4uiEwrIWQ=; b=INjMz3RCfG9FGM4dx8C9qSngvGKjKFAkVcxy/wBiTc5RyMRc5RP4VEbuUVYtyj7NgjCrUH WUdf2U9US0Mnt4CipoKbj9122QtTXFZPPi7oZAKmLcVgB2+U9/3Pp4kmoDtBhLQorZnC6V Rylp2sOikKGyHCFea91lFv0m7w/R/l4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-610-p-vB1GM_P5SZ6DfKCOH2CQ-1; Wed, 16 Feb 2022 05:54:04 -0500 X-MC-Unique: p-vB1GM_P5SZ6DfKCOH2CQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 041188143E5; Wed, 16 Feb 2022 10:54:04 +0000 (UTC) Received: from localhost (unknown [10.39.195.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 97CFA2A194; Wed, 16 Feb 2022 10:53:59 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH v2 1/3] block: Make bdrv_refresh_limits() non-recursive Date: Wed, 16 Feb 2022 11:53:53 +0100 Message-Id: <20220216105355.30729-2-hreitz@redhat.com> In-Reply-To: <20220216105355.30729-1-hreitz@redhat.com> References: <20220216105355.30729-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.083, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: , Cc: Kevin Wolf , Hanna Reitz , Eric Blake , qemu-devel@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" bdrv_refresh_limits() recurses down to the node's children. That does not seem necessary: When we refresh limits on some node, and then recurse down and were to change one of its children's BlockLimits, then that would mean we noticed the changed limits by pure chance. The fact that we refresh the parent's limits has nothing to do with it, so the reason for the change probably happened before this point in time, and we should have refreshed the limits then. On the other hand, we do not have infrastructure for noticing that block limits change after they have been initialized for the first time (this would require propagating the change upwards to the respective node's parents), and so evidently we consider this case impossible. If this case is impossible, then we will not need to recurse down in bdrv_refresh_limits(). Every node's limits are initialized in bdrv_open_driver(), and are refreshed whenever its children change. We want to use the childrens' limits to get some initial default, but we can just take them, we do not need to refresh them. The problem with recursing is that bdrv_refresh_limits() is not atomic. It begins with zeroing BDS.bl, and only then sets proper, valid limits. If we do not drain all nodes whose limits are refreshed, then concurrent I/O requests can encounter invalid request_alignment values and crash qemu. Therefore, a recursing bdrv_refresh_limits() requires the whole subtree to be drained, which is currently not ensured by most callers. A non-recursive bdrv_refresh_limits() only requires the node in question to not receive I/O requests, and this is done by most callers in some way or another: - bdrv_open_driver() deals with a new node with no parents yet - bdrv_set_file_or_backing_noperm() acts on a drained node - bdrv_reopen_commit() acts only on drained nodes - bdrv_append() should in theory require the node to be drained; in practice most callers just lock the AioContext, which should at least be enough to prevent concurrent I/O requests from accessing invalid limits So we can resolve the bug by making bdrv_refresh_limits() non-recursive. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1879437 Signed-off-by: Hanna Reitz Reviewed-by: Eric Blake --- block/io.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/block/io.c b/block/io.c index 4e4cb556c5..c3e7301613 100644 --- a/block/io.c +++ b/block/io.c @@ -189,10 +189,6 @@ void bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error **errp) QLIST_FOREACH(c, &bs->children, next) { if (c->role & (BDRV_CHILD_DATA | BDRV_CHILD_FILTERED | BDRV_CHILD_COW)) { - bdrv_refresh_limits(c->bs, tran, errp); - if (*errp) { - return; - } bdrv_merge_limits(&bs->bl, &c->bs->bl); have_limits = true; } From patchwork Wed Feb 16 10:53:54 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12748417 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 22021C433EF for ; Wed, 16 Feb 2022 10:56:08 +0000 (UTC) Received: from localhost ([::1]:37638 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nKHyh-0001TS-7L for qemu-devel@archiver.kernel.org; Wed, 16 Feb 2022 05:56:07 -0500 Received: from eggs.gnu.org ([209.51.188.92]:52670) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKHxR-0007ev-I5 for qemu-devel@nongnu.org; Wed, 16 Feb 2022 05:54:49 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:60668) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKHxN-0001uQ-EM for qemu-devel@nongnu.org; Wed, 16 Feb 2022 05:54:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645008883; 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: in-reply-to:in-reply-to:references:references; bh=WmXOH52WHHHlkQ8ykG72P/Fg40u1I9GHba+vw+GwmXk=; b=JWOkGTRko9TiVoPf+p+gvqo56uDusYtvdkHL+ZtLpLigyS2aREmkeXnwaRkcl/UsbS2EQY ef+BqFN6EH7YDj26bJFFR496zR+GYCZngnIi5R2v2twJp9YX6msILGg7xe5FwrWH+ddx00 3P+eNqDlhDExd4jqPu/eP7Qcq/WoaDA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-98-7JNYyCx4Pm-c2iDg_tPxUQ-1; Wed, 16 Feb 2022 05:54:42 -0500 X-MC-Unique: 7JNYyCx4Pm-c2iDg_tPxUQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 587D8802924; Wed, 16 Feb 2022 10:54:41 +0000 (UTC) Received: from localhost (unknown [10.39.195.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E1E0578DD9; Wed, 16 Feb 2022 10:54:05 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH v2 2/3] iotests: Allow using QMP with the QSD Date: Wed, 16 Feb 2022 11:53:54 +0100 Message-Id: <20220216105355.30729-3-hreitz@redhat.com> In-Reply-To: <20220216105355.30729-1-hreitz@redhat.com> References: <20220216105355.30729-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.083, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: , Cc: Kevin Wolf , Hanna Reitz , Eric Blake , qemu-devel@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Add a parameter to optionally open a QMP connection when creating a QemuStorageDaemon instance. Signed-off-by: Hanna Reitz Reviewed-by: Eric Blake --- tests/qemu-iotests/iotests.py | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py index 6ba65eb1ff..6027780180 100644 --- a/tests/qemu-iotests/iotests.py +++ b/tests/qemu-iotests/iotests.py @@ -39,6 +39,7 @@ from qemu.machine import qtest from qemu.qmp import QMPMessage +from qemu.aqmp.legacy import QEMUMonitorProtocol # Use this logger for logging messages directly from the iotests module logger = logging.getLogger('qemu.iotests') @@ -348,14 +349,30 @@ def cmd(self, cmd): class QemuStorageDaemon: - def __init__(self, *args: str, instance_id: str = 'a'): + _qmp: Optional[QEMUMonitorProtocol] = None + _qmpsock: Optional[str] = None + # Python < 3.8 would complain if this type were not a string literal + # (importing `annotations` from `__future__` would work; but not on <= 3.6) + _p: 'Optional[subprocess.Popen[bytes]]' = None + + def __init__(self, *args: str, instance_id: str = 'a', qmp: bool = False): assert '--pidfile' not in args self.pidfile = os.path.join(test_dir, f'qsd-{instance_id}-pid') all_args = [qsd_prog] + list(args) + ['--pidfile', self.pidfile] + if qmp: + self._qmpsock = os.path.join(sock_dir, f'qsd-{instance_id}.sock') + all_args += ['--chardev', + f'socket,id=qmp-sock,path={self._qmpsock}', + '--monitor', 'qmp-sock'] + + self._qmp = QEMUMonitorProtocol(self._qmpsock, server=True) + # Cannot use with here, we want the subprocess to stay around # pylint: disable=consider-using-with self._p = subprocess.Popen(all_args) + if self._qmp is not None: + self._qmp.accept() while not os.path.exists(self.pidfile): if self._p.poll() is not None: cmd = ' '.join(all_args) @@ -370,11 +387,24 @@ def __init__(self, *args: str, instance_id: str = 'a'): assert self._pid == self._p.pid + def qmp(self, cmd: str, args: Optional[Dict[str, object]] = None) \ + -> QMPMessage: + assert self._qmp is not None + return self._qmp.cmd(cmd, args) + def stop(self, kill_signal=15): self._p.send_signal(kill_signal) self._p.wait() self._p = None + if self._qmp: + self._qmp.close() + + if self._qmpsock is not None: + try: + os.remove(self._qmpsock) + except OSError: + pass try: os.remove(self.pidfile) except OSError: From patchwork Wed Feb 16 10:53:55 2022 Content-Type: text/plain; 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Wed, 16 Feb 2022 10:54:43 +0000 (UTC) Received: from localhost (unknown [10.39.195.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3B3FC60C2E; Wed, 16 Feb 2022 10:54:43 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH v2 3/3] iotests/graph-changes-while-io: New test Date: Wed, 16 Feb 2022 11:53:55 +0100 Message-Id: <20220216105355.30729-4-hreitz@redhat.com> In-Reply-To: <20220216105355.30729-1-hreitz@redhat.com> References: <20220216105355.30729-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.129.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.083, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Cc: Kevin Wolf , Hanna Reitz , Eric Blake , qemu-devel@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Test the following scenario: 1. Some block node (null-co) attached to a user (here: NBD server) that performs I/O and keeps the node in an I/O thread 2. Repeatedly run blockdev-add/blockdev-del to add/remove an overlay to/from that node Each blockdev-add triggers bdrv_refresh_limits(), and because blockdev-add runs in the main thread, it does not stop the I/O requests. I/O can thus happen while the limits are refreshed, and when such a request sees a temporarily invalid block limit (e.g. alignment is 0), this may easily crash qemu (or the storage daemon in this case). The block layer needs to ensure that I/O requests to a node are paused while that node's BlockLimits are refreshed. Signed-off-by: Hanna Reitz Reviewed-by: Eric Blake --- .../qemu-iotests/tests/graph-changes-while-io | 91 +++++++++++++++++++ .../tests/graph-changes-while-io.out | 5 + 2 files changed, 96 insertions(+) create mode 100755 tests/qemu-iotests/tests/graph-changes-while-io create mode 100644 tests/qemu-iotests/tests/graph-changes-while-io.out diff --git a/tests/qemu-iotests/tests/graph-changes-while-io b/tests/qemu-iotests/tests/graph-changes-while-io new file mode 100755 index 0000000000..567e8cf21e --- /dev/null +++ b/tests/qemu-iotests/tests/graph-changes-while-io @@ -0,0 +1,91 @@ +#!/usr/bin/env python3 +# group: rw +# +# Test graph changes while I/O is happening +# +# Copyright (C) 2022 Red Hat, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . +# + +import os +from threading import Thread +import iotests +from iotests import imgfmt, qemu_img, qemu_img_create, QMPTestCase, \ + QemuStorageDaemon + + +top = os.path.join(iotests.test_dir, 'top.img') +nbd_sock = os.path.join(iotests.sock_dir, 'nbd.sock') + + +def do_qemu_img_bench() -> None: + """ + Do some I/O requests on `nbd_sock`. + """ + assert qemu_img('bench', '-f', 'raw', '-c', '2000000', + f'nbd+unix:///node0?socket={nbd_sock}') == 0 + + +class TestGraphChangesWhileIO(QMPTestCase): + def setUp(self) -> None: + # Create an overlay that can be added at runtime on top of the + # null-co block node that will receive I/O + assert qemu_img_create('-f', imgfmt, '-F', 'raw', '-b', 'null-co://', + top) == 0 + + # QSD instance with a null-co block node in an I/O thread, + # exported over NBD (on `nbd_sock`, export name "node0") + self.qsd = QemuStorageDaemon( + '--object', 'iothread,id=iothread0', + '--blockdev', 'null-co,node-name=node0,read-zeroes=true', + '--nbd-server', f'addr.type=unix,addr.path={nbd_sock}', + '--export', 'nbd,id=exp0,node-name=node0,iothread=iothread0,' + + 'fixed-iothread=true,writable=true', + qmp=True + ) + + def tearDown(self) -> None: + self.qsd.stop() + + def test_blockdev_add_while_io(self) -> None: + # Run qemu-img bench in the background + bench_thr = Thread(target=do_qemu_img_bench) + bench_thr.start() + + # While qemu-img bench is running, repeatedly add and remove an + # overlay to/from node0 + while bench_thr.is_alive(): + result = self.qsd.qmp('blockdev-add', { + 'driver': imgfmt, + 'node-name': 'overlay', + 'backing': 'node0', + 'file': { + 'driver': 'file', + 'filename': top + } + }) + self.assert_qmp(result, 'return', {}) + + result = self.qsd.qmp('blockdev-del', { + 'node-name': 'overlay' + }) + self.assert_qmp(result, 'return', {}) + + bench_thr.join() + +if __name__ == '__main__': + # Format must support raw backing files + iotests.main(supported_fmts=['qcow', 'qcow2', 'qed'], + supported_protocols=['file']) diff --git a/tests/qemu-iotests/tests/graph-changes-while-io.out b/tests/qemu-iotests/tests/graph-changes-while-io.out new file mode 100644 index 0000000000..ae1213e6f8 --- /dev/null +++ b/tests/qemu-iotests/tests/graph-changes-while-io.out @@ -0,0 +1,5 @@ +. +---------------------------------------------------------------------- +Ran 1 tests + +OK