From patchwork Thu Nov 24 10:55:42 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miklos Szeredi X-Patchwork-Id: 9445179 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 58B916075F for ; Thu, 24 Nov 2016 10:56:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 62EC81FF1E for ; Thu, 24 Nov 2016 10:56:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5658127B81; Thu, 24 Nov 2016 10:56:26 +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=-6.4 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM 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 063531FF1E for ; Thu, 24 Nov 2016 10:56:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964995AbcKXK4C (ORCPT ); Thu, 24 Nov 2016 05:56:02 -0500 Received: from mail-wm0-f47.google.com ([74.125.82.47]:36649 "EHLO mail-wm0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964981AbcKXKz7 (ORCPT ); Thu, 24 Nov 2016 05:55:59 -0500 Received: by mail-wm0-f47.google.com with SMTP id g23so109711794wme.1 for ; Thu, 24 Nov 2016 02:55:57 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=qu1NB0HAMqIndxuBHhKVKNYwM/yEL6QPuIqd07gnZRA=; b=PfdI2GLLJ3tw5tdWq1P9JXkEm+0XqBRjfME3r28i4vlRtTB1bOtY1bSsNttMZ19pzG AoyqW4lmzEr8s66p50dfiqYg9EBn0OPtpE+3BwtGWnvftELwrx3eMJ2y65FJ5rhbTt6E 2C+qogYCXAkyH9rCbHdfFHd6OnJ/2Iz9t2DJhJtZR3fvHWKHh8rLntZCrqIt+/KGXKi9 lo2m65u7obnq/XeV/Ttw0m3grZMvUrKzwRmZ5xxaz9dwpbL6dLDJ15zryb10WET4riT3 K2Am1J+vWg6gz/f5tAqznogk8N33LHPOXqh5HmePvyxZGugs2YeCFBWnreZZVa9MHJoy 0w9w== X-Gm-Message-State: AKaTC02C76cqJal3BFNFENYyJ5V8usGKG0l90PIsb3+XAbJq/joXVmWm0AVYW9jrLv2WQcnt X-Received: by 10.28.181.197 with SMTP id e188mr1669992wmf.32.1479984956337; Thu, 24 Nov 2016 02:55:56 -0800 (PST) Received: from veci.piliscsaba.szeredi.hu (pool-dsl-2c-0018.externet.hu. [217.173.44.24]) by smtp.gmail.com with ESMTPSA id g73sm7587416wme.16.2016.11.24.02.55.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 24 Nov 2016 02:55:55 -0800 (PST) From: Miklos Szeredi To: linux-unionfs@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 5/7] ovl: intercept read_iter Date: Thu, 24 Nov 2016 11:55:42 +0100 Message-Id: <1479984944-1017-7-git-send-email-mszeredi@redhat.com> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1479984944-1017-1-git-send-email-mszeredi@redhat.com> References: <1479984944-1017-1-git-send-email-mszeredi@redhat.com> 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 ...in order to handle the corner case when the file is copyied up after being opened read-only. Can be verified with the following script: - 8< - - - - - 8< - - - - - 8< - - - - - 8< - - - - cd / rm -rf /tmp/ovl-rorw-test mkdir /tmp/ovl-rorw-test cd /tmp/ovl-rorw-test mkdir -p mnt lower upper work echo baba > lower/foo mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work mnt exec 3< mnt/foo echo bubu > mnt/foo cat <&3 exec 3>&- umount mnt - 8< - - - - - 8< - - - - - 8< - - - - - 8< - - - - Correct output is "bubu", incorrect output is "baba". Signed-off-by: Miklos Szeredi --- fs/overlayfs/inode.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 3e26615c4697..09c6f99bd5db 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include "overlayfs.h" @@ -368,6 +369,29 @@ void ovl_cleanup_fops_htable(void) __ofop->orig_fops->call; \ }) +static bool ovl_file_is_lower(struct file *file) +{ + return !OVL_TYPE_UPPER(ovl_path_type(file->f_path.dentry)); +} + +static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *to) +{ + struct file *file = iocb->ki_filp; + ssize_t ret; + + if (likely(ovl_file_is_lower(file))) + return OVL_CALL_REAL_FOP(file, read_iter(iocb, to)); + + file = filp_clone_open(file); + if (IS_ERR(file)) + return PTR_ERR(file); + + ret = vfs_iter_read(file, to, &iocb->ki_pos); + fput(file); + + return ret; +} + static struct ovl_fops *ovl_fops_find(const struct file_operations *orig) { struct ovl_fops *ofop; @@ -404,8 +428,11 @@ static struct ovl_fops *ovl_fops_get(struct file *file) ofop->magic = OVL_FOPS_MAGIC; ofop->orig_fops = fops_get(orig); + /* Intercept these: */ + if (orig->read_iter) + ofop->fops.read_iter = ovl_read_iter; + /* These will need to be intercepted: */ - ofop->fops.read_iter = orig->read_iter; ofop->fops.mmap = orig->mmap; ofop->fops.fsync = orig->fsync;