From patchwork Wed Jun 22 10:13:08 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: zhangaihua1@huawei.com X-Patchwork-Id: 9192353 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 080626075C for ; Wed, 22 Jun 2016 10:11:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EAC612819A for ; Wed, 22 Jun 2016 10:11:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DF3BF283E9; Wed, 22 Jun 2016 10:11:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7D30F2819A for ; Wed, 22 Jun 2016 10:11:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750866AbcFVKLk (ORCPT ); Wed, 22 Jun 2016 06:11:40 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:6914 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750910AbcFVKLi (ORCPT ); Wed, 22 Jun 2016 06:11:38 -0400 Received: from 172.24.1.137 (EHLO szxeml422-hub.china.huawei.com) ([172.24.1.137]) by szxrg03-dlp.huawei.com (MOS 4.4.3-GA FastPath queued) with ESMTP id CDS36839; Wed, 22 Jun 2016 18:06:18 +0800 (CST) Received: from localhost.localdomain (10.175.100.166) by szxeml422-hub.china.huawei.com (10.82.67.152) with Microsoft SMTP Server id 14.3.235.1; Wed, 22 Jun 2016 18:06:08 +0800 From: To: , , CC: Aihua Zhang Subject: [PATCH] fix error: a bin file can truncate itself while running on overlayfs Date: Wed, 22 Jun 2016 18:13:08 +0800 Message-ID: <1466590388-4914-1-git-send-email-zhangaihua1@huawei.com> X-Mailer: git-send-email 1.7.1 MIME-Version: 1.0 X-Originating-IP: [10.175.100.166] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090205.576A631B.0093, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 0e30d5150c0803943656fe3a03438dc3 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Aihua Zhang I wrote a testcase to truncate a bin file while it is running on overlayfs. the mount: /dev/mapper/fedora-home on /home type ext4 (rw,relatime,data=ordered) overlay on /tmp type overlay (rw,relatime,lowerdir=/home/zah/lower, upperdir=/home/zah/upper,workdir=/home/zah/workdir) the code cpp: int main(int argc, char *argv[]) { int status; pthread_t thread; int err; char *ptr; ptr = basename(argv[0]); printf("%s\n",ptr); errno = 0; status = truncate(ptr, 4096); printf("status:%d\n",status); printf("errno:%d\n",errno); printf("ETXTBSY:%d\n",ETXTBSY); if ((-1 == status) && (ETXTBSY == errno)) { printf("PASS\n"); return 0; } err = errno; printf("err = %d\n", err); printf("FAIL\n"); return 1; } I running the test on overlayfs, the result as below: Bus error (core dumped) and running the test on ext4, the result as below: status:-1 errno:26 ETXTBSY:26 PASS I add some log, and I find the inode is not correct on overlayfs, and the inode->i_writecount is not correct also called by vfs_truncate-> get_write_access(), the log as below: Jun 22 09:50:38 kernel: [131.872920] deny_write_access: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873109] deny_write_access: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873110] __vma_link_file: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873112] allow_write_access: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873114] deny_write_access: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873115] __vma_link_file: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873116] allow_write_access: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873162] allow_write_access: inode ino 64104618 Jun 22 09:50:38 kernel: [131.873947] __vma_link_file: inode ino 64104618 Jun 22 09:50:38 kernel: [131.874039] vfs_truncate: inode ino:24061 before vfs_truncate, the inode is point to upper filesystem(ext4), and in vfs_truncate the inode is point to overlayfs. So, I fix it by geting the real inode via ovl_d_select_inode. Signed-off-by: Aihua Zhang --- fs/open.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/open.c b/fs/open.c index 93ae3cd..43b17d1 100644 --- a/fs/open.c +++ b/fs/open.c @@ -67,10 +67,16 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, long vfs_truncate(const struct path *path, loff_t length) { + struct dentry *dentry = path->dentry; struct inode *inode; long error; - inode = path->dentry->d_inode; + if (dentry->d_flags & DCACHE_OP_SELECT_INODE) { + inode = dentry->d_op->d_select_inode(dentry, O_TRUNC); + if (IS_ERR(inode)) + return PTR_ERR(inode); + } else + inode = dentry->d_inode; /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ if (S_ISDIR(inode->i_mode)) @@ -106,7 +112,7 @@ long vfs_truncate(const struct path *path, loff_t length) if (!error) error = security_path_truncate(path); if (!error) - error = do_truncate(path->dentry, length, 0, NULL); + error = do_truncate(dentry, length, 0, NULL); put_write_and_out: put_write_access(inode);