From patchwork Thu Dec 1 10:15:00 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miklos Szeredi X-Patchwork-Id: 9455745 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 27B2D60515 for ; Thu, 1 Dec 2016 10:16:36 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 17B65284CB for ; Thu, 1 Dec 2016 10:16:36 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0CBAA284CF; Thu, 1 Dec 2016 10:16:36 +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 AF224284CB for ; Thu, 1 Dec 2016 10:16:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756967AbcLAKQQ (ORCPT ); Thu, 1 Dec 2016 05:16:16 -0500 Received: from mail-wj0-f176.google.com ([209.85.210.176]:33510 "EHLO mail-wj0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756009AbcLAKPO (ORCPT ); Thu, 1 Dec 2016 05:15:14 -0500 Received: by mail-wj0-f176.google.com with SMTP id xy5so199960123wjc.0 for ; Thu, 01 Dec 2016 02:15:13 -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=bsBLYDaJ2sllFaFNZIr4VUmzdpBqE53lwvPtA5KJttU=; b=bhvMc3Q4L8x73yA1KzzfPMT+TY2cCYZaHt36v4znzyCJs6uMUwQPoKUciNtWngagBu cDK8v+TGFQhU8gbNKwqZXC5zuBPMiOH0zXyrM/971sH6d7CS5fYRdMrSz6Jybtpw4NeZ 2dxqa3Yrt0AzNFKujw+zCun+u6TrOWif+alDzB9bw1txqAW4ef9dT00EZR1ZmG//aJD2 sJlVmOVFxMb3Du49noEj3z1Eq8HpI2epMAfKJTMlSeBago4T834Lzh5s8btaSXu8jWFf XRa1entq2JAeH8TMf4rH+ynJpQbjABiz8absznM3Rc30HuZ2iYypmu2oav1DonFBvnOm bg/A== X-Gm-Message-State: AKaTC03ZntTBn10lUryvZh0tcXaAWDQ15xof1BXq0WiuKDFD0NAhDYdXps5TTtswin+ndxe4 X-Received: by 10.194.121.6 with SMTP id lg6mr37842788wjb.105.1480587312714; Thu, 01 Dec 2016 02:15:12 -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 ab10sm77218141wjc.45.2016.12.01.02.15.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Dec 2016 02:15:11 -0800 (PST) From: Miklos Szeredi To: Al Viro Cc: linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH 5/8] ovl: intercept read_iter Date: Thu, 1 Dec 2016 11:15:00 +0100 Message-Id: <1480587303-25088-6-git-send-email-mszeredi@redhat.com> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1480587303-25088-1-git-send-email-mszeredi@redhat.com> References: <1480587303-25088-1-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 e98e3323c330..a2d5b3d03e14 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; @@ -406,8 +430,11 @@ 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;