From patchwork Fri Oct 25 09:58:49 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 1184007 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="LpB+bMJ3"; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 4700gy35Zyz9s7T for ; Fri, 25 Oct 2019 21:28:28 +1100 (AEDT) Received: from localhost ([::1]:58316 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iNwpU-0006jI-QV for incoming@patchwork.ozlabs.org; Fri, 25 Oct 2019 06:28:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60889) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iNwNN-0006lU-PT for qemu-devel@nongnu.org; Fri, 25 Oct 2019 05:59:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iNwNM-0004nZ-Lu for qemu-devel@nongnu.org; Fri, 25 Oct 2019 05:59:21 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:32049 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iNwNM-0004mr-Ac for qemu-devel@nongnu.org; Fri, 25 Oct 2019 05:59:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571997558; 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=XpsKnDhhSg9Wa3tqe3NS161Z+XJaiocRkSfdBx9/23U=; b=LpB+bMJ3a9LGKruUL84bm3sNPazEdvuv9TAo5hfCReDPyRjDxiKF+6jrUa2MCnx/zvSX4q QHG4i1ZG8QEIvEUm3tBGX20Lb4vNgGiqCWqeluEOkUFzi2i/vPiRkMcfoEiliXy8Ot/qYq GIZpOnqBMAT/Z6pQ81+Ol4XvwmrLPLI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-258-P_a8lt4PO8-w_kZgh-nW7w-1; Fri, 25 Oct 2019 05:59:15 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F0AD680183D; Fri, 25 Oct 2019 09:59:13 +0000 (UTC) Received: from localhost (ovpn-117-205.ams2.redhat.com [10.36.117.205]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 099065C1B5; Fri, 25 Oct 2019 09:59:10 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [RFC 3/3] block/file-posix: Let post-EOF fallocate serialize Date: Fri, 25 Oct 2019 11:58:49 +0200 Message-Id: <20191025095849.25283-4-mreitz@redhat.com> In-Reply-To: <20191025095849.25283-1-mreitz@redhat.com> References: <20191025095849.25283-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-MC-Unique: P_a8lt4PO8-w_kZgh-nW7w-1 X-Mimecast-Spam-Score: 0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Anton Nefedov , Alberto Garcia , qemu-devel@nongnu.org, Max Reitz , Vladimir Sementsov-Ogievskiy , Stefan Hajnoczi Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" The XFS kernel driver has a bug that may cause data corruption for qcow2 images as of qemu commit c8bb23cbdbe32f. We can work around it by treating post-EOF fallocates as serializing up until infinity (INT64_MAX in practice). Signed-off-by: Max Reitz --- block/file-posix.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/block/file-posix.c b/block/file-posix.c index 5cd54c8bff..1f5a01df70 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -2713,6 +2713,48 @@ raw_do_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes, RawPosixAIOData acb; ThreadPoolFunc *handler; +#ifdef CONFIG_FALLOCATE + if (s->is_xfs && s->use_linux_aio && + offset + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) + { + BdrvTrackedRequest *req; + uint64_t end; + + /* + * The Linux XFS driver has a bug where it will discard writes + * submitted through the AIO interface if they happen beyond a + * concurrently running fallocate() that increases the file + * length (i.e., both the write and the fallocate() happen + * beyond the EOF). + * + * To work around it, we look for the tracked request for this + * zero write, extend it until INT64_MAX (effectively + * infinity), and mark it as serializing. + * + * TODO: Detect whether this has been fixed in the XFS driver. + */ + + QLIST_FOREACH(req, &bs->tracked_requests, list) { + if (req->co == qemu_coroutine_self() && + req->type == BDRV_TRACKED_WRITE) + { + break; + } + } + + assert(req); + assert(req->offset <= offset); + assert(req->offset + req->bytes >= offset + bytes); + + end = INT64_MAX & -(uint64_t)bs->bl.request_alignment; + req->bytes = end - req->offset; + req->overlap_bytes = req->bytes; + + bdrv_mark_request_serialising(req, bs->bl.request_alignment); + bdrv_wait_serialising_requests(req); + } +#endif + acb = (RawPosixAIOData) { .bs = bs, .aio_fildes = s->fd,