From patchwork Mon Sep 30 09:11:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Su Yanjun X-Patchwork-Id: 11166225 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D6A891599 for ; Mon, 30 Sep 2019 09:13:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD99F21855 for ; Mon, 30 Sep 2019 09:13:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729404AbfI3JNz (ORCPT ); Mon, 30 Sep 2019 05:13:55 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:49177 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726121AbfI3JNz (ORCPT ); Mon, 30 Sep 2019 05:13:55 -0400 X-IronPort-AV: E=Sophos;i="5.64,565,1559491200"; d="scan'208";a="76258074" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 30 Sep 2019 17:13:53 +0800 Received: from G08CNEXCHPEKD03.g08.fujitsu.local (unknown [10.167.33.85]) by cn.fujitsu.com (Postfix) with ESMTP id 73F414CE14F9; Mon, 30 Sep 2019 17:13:57 +0800 (CST) Received: from localhost.localdomain (10.167.226.33) by G08CNEXCHPEKD03.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 30 Sep 2019 17:13:57 +0800 From: Su Yanjun To: CC: , , Subject: [PATCH] NFS: Fix O_DIRECT read problem when another write is going on Date: Mon, 30 Sep 2019 17:11:18 +0800 Message-ID: <1569834678-16117-1-git-send-email-suyj.fnst@cn.fujitsu.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.167.226.33] X-yoursite-MailScanner-ID: 73F414CE14F9.AFB38 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: suyj.fnst@cn.fujitsu.com X-Spam-Status: No Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org In xfstests generic/465 tests failed. Because O_DIRECT r/w use async rpc calls, when r/w rpc calls are running concurrently we may read partial data which is wrong. For example as follows. user buffer /--------\ | |XXXX| rpc0 rpc1 When rpc0 runs it encounters eof so return 0, then another writes something. When rpc1 runs it returns some data. The total data buffer contains wrong data. In this patch we check eof mark for each direct request. If encounters eof then set eof mark in the request, when we meet it again report -EAGAIN error. In nfs_direct_complete we convert -EAGAIN as if read nothing. When the reader issue another read it will read ok. Signed-off-by: Su Yanjun --- fs/nfs/direct.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index 222d711..7f737a3 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -93,6 +93,7 @@ struct nfs_direct_req { bytes_left, /* bytes left to be sent */ error; /* any reported error */ struct completion completion; /* wait for i/o completion */ + int eof; /* eof mark in the req */ /* commit state */ struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */ @@ -380,6 +381,12 @@ static void nfs_direct_complete(struct nfs_direct_req *dreq) { struct inode *inode = dreq->inode; + /* read partial data just as read nothing */ + if (dreq->error == -EAGAIN) { + dreq->count = 0; + dreq->error = 0; + } + inode_dio_end(inode); if (dreq->iocb) { @@ -413,8 +420,13 @@ static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) if (hdr->good_bytes != 0) nfs_direct_good_bytes(dreq, hdr); - if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) + if (dreq->eof) + dreq->error = -EAGAIN; + + if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { dreq->error = 0; + dreq->eof = 1; + } spin_unlock(&dreq->lock);