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=-8.0 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,UNPARSEABLE_RELAY,USER_AGENT_MUTT autolearn=unavailable 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 8257FC43613 for ; Thu, 20 Jun 2019 22:11:01 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (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 43C642070B; Thu, 20 Jun 2019 22:11:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sourceforge.net header.i=@sourceforge.net header.b="VHQBzzLk"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sf.net header.i=@sf.net header.b="SOj1FJeY"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="wEo3wGjo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 43C642070B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-f2fs-devel-bounces@lists.sourceforge.net Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.90_1) (envelope-from ) id 1he5Gj-00033l-Te; Thu, 20 Jun 2019 22:10:57 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1he5Gi-00033S-BN for linux-f2fs-devel@lists.sourceforge.net; Thu, 20 Jun 2019 22:10:56 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=34yrDpyIlCnapuEelQkMxzELpTn9E3Oq0EEgTNp3pMo=; b=VHQBzzLkz1ofnBu+DOKsb2kKQc 9r6sGztmtEJ0CptOkYoHbExFsG7CwvsnSbK7CGKV9l8lNbkFGtiqMEbojHmtfli2jcMIVsjoLGRcK Vcs6H77KIOW8OVWy+7hlkOHIrz6r5UzQCGaystCp9H5SGzSSZ8zBFYC995nYLGXV5b3E=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To :From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=34yrDpyIlCnapuEelQkMxzELpTn9E3Oq0EEgTNp3pMo=; b=SOj1FJeYXBt77fGJrqjiLiopPd 5lzwj32vxnMYA9YTTV6zNeIg2AQq32VIT3+lxP79NnQciFrvyefGhCJ4kCJHucN9/acS33zsHDce4 H52y6QMvUaDdqbEzapvotke0aM4TXpCnyOF1AvFYYOj7yn6ZOCvO9XVQzfFqk7J8b2bQ=; Received: from userp2120.oracle.com ([156.151.31.85]) by sfi-mx-4.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1he5Gj-006bzr-Ja for linux-f2fs-devel@lists.sourceforge.net; Thu, 20 Jun 2019 22:10:58 +0000 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x5KM3qBJ117650; Thu, 20 Jun 2019 22:09:48 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=34yrDpyIlCnapuEelQkMxzELpTn9E3Oq0EEgTNp3pMo=; b=wEo3wGjoiDRLmfFiBOSYftkqF9BxyNKUscmBHul8oqMnrOQ2CuuZil1ROkycJEV6VL7i K/EZENHDp/fbYpjQeBCVWiy/W0Tz7wb4eQqeU8hP8XSZ126W7yTiTbuSaF2YghMDkyDz 1JjI5jgZUM6pLkd8QOel+rUwWuFInCdHZHVl+HAdZhL5eL30xXYf07aNzmm5sQfUY3Xi u8qnsSTO1Nnw83kcS80Cgv88V0Im23B5q/abGAirRb0yn4qxQanHw+7gT0cIk1IKOss/ NQ08jOFoC7P0Gxtp1eUAT6k37gmOMLQ6i9bzdXCoNF+Y2BY5IL9mn4FAiou7/jCFeHkN BA== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2120.oracle.com with ESMTP id 2t7809kfc9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 20 Jun 2019 22:09:48 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x5KM9DaG104726; Thu, 20 Jun 2019 22:09:47 GMT Received: from pps.reinject (localhost [127.0.0.1]) by userp3020.oracle.com with ESMTP id 2t77ynv76j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 20 Jun 2019 22:09:47 +0000 Received: from userp3020.oracle.com (userp3020.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.27/8.16.0.27) with SMTP id x5KM9lfD106008; Thu, 20 Jun 2019 22:09:47 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3020.oracle.com with ESMTP id 2t77ynv76b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 20 Jun 2019 22:09:47 +0000 Received: from abhmp0015.oracle.com (abhmp0015.oracle.com [141.146.116.21]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x5KM9hLr020247; Thu, 20 Jun 2019 22:09:43 GMT Received: from localhost (/10.145.179.81) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 20 Jun 2019 15:09:43 -0700 Date: Thu, 20 Jun 2019 15:09:40 -0700 From: "Darrick J. Wong" To: Jan Kara Message-ID: <20190620220940.GC5375@magnolia> References: <156022836912.3227213.13598042497272336695.stgit@magnolia> <156022838496.3227213.3771632042609589318.stgit@magnolia> <20190620140028.GH30243@quack2.suse.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190620140028.GH30243@quack2.suse.cz> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9294 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=772 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906200158 X-Headers-End: 1he5Gj-006bzr-Ja Subject: Re: [f2fs-dev] [PATCH 2/6] vfs: flush and wait for io when setting the immutable flag via SETFLAGS X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-efi@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org, clm@fb.com, adilger.kernel@dilger.ca, matthew.garrett@nebula.com, linux-nilfs@vger.kernel.org, linux-ext4@vger.kernel.org, devel@lists.orangefs.org, josef@toxicpanda.com, reiserfs-devel@vger.kernel.org, viro@zeniv.linux.org.uk, dsterba@suse.com, jaegeuk@kernel.org, tytso@mit.edu, ard.biesheuvel@linaro.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, jk@ozlabs.org, jack@suse.com, linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org, ocfs2-devel@oss.oracle.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Thu, Jun 20, 2019 at 04:00:28PM +0200, Jan Kara wrote: > On Mon 10-06-19 21:46:25, Darrick J. Wong wrote: > > From: Darrick J. Wong > > > > When we're using FS_IOC_SETFLAGS to set the immutable flag on a file, we > > need to ensure that userspace can't continue to write the file after the > > file becomes immutable. To make that happen, we have to flush all the > > dirty pagecache pages to disk to ensure that we can fail a page fault on > > a mmap'd region, wait for pending directio to complete, and hope the > > caller locked out any new writes by holding the inode lock. > > > > Signed-off-by: Darrick J. Wong > > ... > > > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c > > index 6aa1df1918f7..a05341b94d98 100644 > > --- a/fs/ext4/ioctl.c > > +++ b/fs/ext4/ioctl.c > > @@ -290,6 +290,9 @@ static int ext4_ioctl_setflags(struct inode *inode, > > jflag = flags & EXT4_JOURNAL_DATA_FL; > > > > err = vfs_ioc_setflags_check(inode, oldflags, flags); > > + if (err) > > + goto flags_out; > > + err = vfs_ioc_setflags_flush_data(inode, flags); > > if (err) > > goto flags_out; > > > > ... > > > diff --git a/include/linux/fs.h b/include/linux/fs.h > > index 8dad3c80b611..9c899c63957e 100644 > > --- a/include/linux/fs.h > > +++ b/include/linux/fs.h > > @@ -3548,7 +3548,41 @@ static inline struct sock *io_uring_get_socket(struct file *file) > > > > int vfs_ioc_setflags_check(struct inode *inode, int oldflags, int flags); > > > > +/* > > + * Do we need to flush the file data before changing attributes? When we're > > + * setting the immutable flag we must stop all directio writes and flush the > > + * dirty pages so that we can fail the page fault on the next write attempt. > > + */ > > +static inline bool vfs_ioc_setflags_need_flush(struct inode *inode, int flags) > > +{ > > + if (S_ISREG(inode->i_mode) && !IS_IMMUTABLE(inode) && > > + (flags & FS_IMMUTABLE_FL)) > > + return true; > > + > > + return false; > > +} > > + > > +/* > > + * Flush file data before changing attributes. Caller must hold any locks > > + * required to prevent further writes to this file until we're done setting > > + * flags. > > + */ > > +static inline int inode_flush_data(struct inode *inode) > > +{ > > + inode_dio_wait(inode); > > + return filemap_write_and_wait(inode->i_mapping); > > +} > > + > > +/* Flush file data before changing attributes, if necessary. */ > > +static inline int vfs_ioc_setflags_flush_data(struct inode *inode, int flags) > > +{ > > + if (vfs_ioc_setflags_need_flush(inode, flags)) > > + return inode_flush_data(inode); > > + return 0; > > +} > > + > > But this is racy at least for page faults, isn't it? What protects you > against write faults just after filemap_write_and_wait() has finished? > So either you need to set FS_IMMUTABLE_FL before flushing data or you need > to get more protection from the fs than just i_rwsem. In the case of ext4 > that would be i_mmap_rwsem but other filesystems don't have equivalent > protection... Yes, I see that now. I think it'll work to set S_IMMUTABLE before trying the flush, so long as I am careful to put the call sites right before we update the inode flags. --D > > Honza > -- > Jan Kara > SUSE Labs, CR _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel