From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 697CFCA9ECF for ; Fri, 1 Nov 2019 10:07:30 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 342AE2086D for ; Fri, 1 Nov 2019 10:07:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GttoklKS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 342AE2086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37210 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iQTq4-0003OP-Av for qemu-devel@archiver.kernel.org; Fri, 01 Nov 2019 06:07:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40483) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iQTk4-0007Li-GS for qemu-devel@nongnu.org; Fri, 01 Nov 2019 06:01:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iQTk1-0006oq-8v for qemu-devel@nongnu.org; Fri, 01 Nov 2019 06:01:15 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:37162 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iQTjw-00068C-Sm for qemu-devel@nongnu.org; Fri, 01 Nov 2019 06:01:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1572602456; 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=CSfDgngGZU4Dl9sNhabdfyOvZuYyfclSjEtzmRhnADY=; b=GttoklKSG2Fu5ECDKsIXM4CkpUN/NvCNS65BXuL4JhRu+3l6iXyTS5uZKxHs+765u4U0dA v4CPnRbSl9n4yfYYZRtfhgTUEvzPhhNODPLXP4DhzS5aJ43Sy8KpVMiqm4/oVpbpfhjAHH tS+a2OnkHSoK0GzhVKr70Rz3L/j/zWU= 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-228-2rhOLzh1P56fZs8QHJF0lw-1; Fri, 01 Nov 2019 06:00:52 -0400 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 54FFE2A3; Fri, 1 Nov 2019 10:00:51 +0000 (UTC) Received: from localhost (ovpn-117-28.ams2.redhat.com [10.36.117.28]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3332860C18; Fri, 1 Nov 2019 10:00:43 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH for-4.2 4/4] block/file-posix: Let post-EOF fallocate serialize Date: Fri, 1 Nov 2019 11:00:19 +0100 Message-Id: <20191101100019.9512-5-mreitz@redhat.com> In-Reply-To: <20191101100019.9512-1-mreitz@redhat.com> References: <20191101100019.9512-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: 2rhOLzh1P56fZs8QHJF0lw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 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 , qemu-devel@nongnu.org, Max Reitz , Vladimir Sementsov-Ogievskiy , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The XFS kernel driver has a bug that may cause data loss when using fallocate() in an I/O path, i.e. writing zeroes. 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 | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/block/file-posix.c b/block/file-posix.c index 0b7e904d48..d5460f3e45 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -2721,6 +2721,44 @@ raw_do_pwrite_zeroes(BlockDriverState *bs, int64_t o= ffset, int bytes, RawPosixAIOData acb; ThreadPoolFunc *handler; =20 +#ifdef CONFIG_FALLOCATE + if (offset + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) { + BdrvTrackedRequest *req; + uint64_t end; + + /* + * This is a workaround for a bug in the Linux XFS driver, + * where writes submitted through the AIO interface will be + * discarded 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 extend the tracked request for this + * zero write until INT64_MAX (effectively infinity), and mark + * it as serializing. + * + * We have to enable this workaround for all filesystems and + * AIO modes (not just XFS with aio=3Dnative), because for + * remote filesystems we do not know the host configuration. + * However, this should have no effect as long as no block + * driver submits zero writes beyond the EOF. + */ + + req =3D bdrv_co_get_self_request(bs); + assert(req); + assert(req->type =3D=3D BDRV_TRACKED_WRITE); + assert(req->offset <=3D offset); + assert(req->offset + req->bytes >=3D offset + bytes); + + end =3D INT64_MAX & -(uint64_t)bs->bl.request_alignment; + req->bytes =3D end - req->offset; + req->overlap_bytes =3D req->bytes; + + bdrv_mark_request_serialising(req, bs->bl.request_alignment); + bdrv_wait_serialising_requests(req); + } +#endif + acb =3D (RawPosixAIOData) { .bs =3D bs, .aio_fildes =3D s->fd, --=20 2.21.0