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=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 182DFC43613 for ; Mon, 24 Jun 2019 11:37:58 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 E04BB20674 for ; Mon, 24 Jun 2019 11:37:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="JotD6/ik" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E04BB20674 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=DRwP6hzsBrDo50S906enueKnp427bFnlVjrt+yE3DYI=; b=JotD6/ikH3cgYY F3nh+XR3vM8iEei5c6GOH+nQiLGltqoaqYp0JNXuYyTdYifusAA6ZS1zG4c9DMUROjC3Jy4Ylwygb bkL1sixrIQeMvFvDLTxT54Fpw9G0ratEgLq2tCxkwmN8bTwoYEkZn72is7Juv5+Y0LYdHICbdgH7y o8GA8mNR91UgFQVaekREU3IrbFF9elWGdvpcHdDu1+kgaEfbXPL7OG3ruXIZZMBqriOV/ejRbegJ2 LyN91g/863kuiAfxBtYV71aVeCvWarQs7ylnEhyCorMIR0tnr69i5W+XKid/rljOmPnO/apKon0DR AnaV3k1xwTYDpNw3XCdw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hfNI8-0000eR-Be; Mon, 24 Jun 2019 11:37:44 +0000 Received: from mx2.suse.de ([195.135.220.15] helo=mx1.suse.de) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hfNI5-0000e8-Q1 for linux-mtd@lists.infradead.org; Mon, 24 Jun 2019 11:37:43 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0EF03AE79; Mon, 24 Jun 2019 11:37:40 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id DBCD31E2F23; Mon, 24 Jun 2019 13:37:37 +0200 (CEST) Date: Mon, 24 Jun 2019 13:37:37 +0200 From: Jan Kara To: "Darrick J. Wong" Subject: Re: [PATCH 2/7] vfs: flush and wait for io when setting the immutable flag via SETFLAGS Message-ID: <20190624113737.GG32376@quack2.suse.cz> References: <156116141046.1664939.11424021489724835645.stgit@magnolia> <156116142734.1664939.5074567130774423066.stgit@magnolia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <156116142734.1664939.5074567130774423066.stgit@magnolia> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190624_043741_995382_2A0BA2D4 X-CRM114-Status: GOOD ( 14.58 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-efi@vger.kernel.org, linux-btrfs@vger.kernel.org, yuchao0@huawei.com, 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 Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Fri 21-06-19 16:57:07, 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 Seeing the way this worked out, is there a reason to have separate vfs_ioc_setflags_flush_data() instead of folding the functionality in vfs_ioc_setflags_check() (possibly renaming it to vfs_ioc_setflags_prepare() to indicate it does already some changes)? I don't see any place that would need these two separated... > +/* > + * Flush all pending IO and dirty mappings before setting S_IMMUTABLE on an > + * inode via FS_IOC_SETFLAGS. If the flush fails we'll clear the flag before > + * returning error. > + * > + * Note: the caller should be holding i_mutex, or else be sure that > + * they have exclusive access to the inode structure. > + */ > +static inline int vfs_ioc_setflags_flush_data(struct inode *inode, int flags) > +{ > + int ret; > + > + if (!vfs_ioc_setflags_need_flush(inode, flags)) > + return 0; > + > + inode_set_flags(inode, S_IMMUTABLE, S_IMMUTABLE); > + ret = inode_flush_data(inode); > + if (ret) > + inode_set_flags(inode, 0, S_IMMUTABLE); > + return ret; > +} Also this sets S_IMMUTABLE whenever vfs_ioc_setflags_need_flush() returns true. That is currently the right thing but seems like a landmine waiting to trip? So I'd just drop the vfs_ioc_setflags_need_flush() abstraction to make it clear what's going on. Honza -- Jan Kara SUSE Labs, CR ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/