From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755030Ab2CLMdj (ORCPT ); Mon, 12 Mar 2012 08:33:39 -0400 Received: from mga01.intel.com ([192.55.52.88]:6535 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753759Ab2CLMdg (ORCPT ); Mon, 12 Mar 2012 08:33:36 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="127771237" Message-ID: <1331555774.12037.9.camel@sauron.fi.intel.com> Subject: Re: [PATCH 5/9] writeback: introduce the pageout work From: Artem Bityutskiy Reply-To: dedekind1@gmail.com To: Jan Kara Cc: Fengguang Wu , Andrew Morton , Greg Thelen , Ying Han , "hannes@cmpxchg.org" , KAMEZAWA Hiroyuki , Rik van Riel , Mel Gorman , Minchan Kim , Linux Memory Management List , LKML , Adrian Hunter Date: Mon, 12 Mar 2012 14:36:14 +0200 In-Reply-To: <20120309211156.GA6262@quack.suse.cz> References: <20120301163837.GA13104@quack.suse.cz> <20120302044858.GA14802@localhost> <20120302095910.GB1744@quack.suse.cz> <20120302103951.GA13378@localhost> <20120302115700.7d970497.akpm@linux-foundation.org> <20120303135558.GA9869@localhost> <1331135301.32316.29.camel@sauron.fi.intel.com> <20120309073113.GA5337@localhost> <20120309095135.GC21038@quack.suse.cz> <1331309451.29445.42.camel@sauron.fi.intel.com> <20120309211156.GA6262@quack.suse.cz> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 (3.2.3-1.fc16) Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2012-03-09 at 22:11 +0100, Jan Kara wrote: > On Fri 09-03-12 18:10:51, Artem Bityutskiy wrote: > > On Fri, 2012-03-09 at 10:51 +0100, Jan Kara wrote: > > > > However I cannot find any ubifs functions to form the above loop, so > > > > ubifs should be safe for now. > > > Yeah, me neither but I also failed to find a place where > > > ubifs_evict_inode() truncates inode space when deleting the inode... Artem? > > > > We do call 'truncate_inode_pages()': > > > > static void ubifs_evict_inode(struct inode *inode) > > { > > ... > > > > truncate_inode_pages(&inode->i_data, 0); > > > > ... > > } > Well, but that just removes pages from page cache. You should somewhere > also free allocated blocks and free the inode... And I'm sure you do, > otherwise you would pretty quickly notice that file deletion does not work > :) Just I could not find which function does it. ubifs_evict_inode() -> ubifs_jnl_delete_inode() -> ubifs_tnc_remove_ino() Basically, deletion in UBIFS is about writing a so-called "deletion inode" to the journal and then removing all the data nodes of the truncated inode from the TNC (in-memory cache of the FS index, which is just a huge B-tree, like in reiser4 which inspired me long time ago, and like in btrfs). The second part of the overall deletion job will be when we commit - the updated version of the FS index will be written to the flash media. If we get a power cut before the commit, the journal reply will see the deletion inode and will clean-up the index. The deletion inode is never erased before the commit. Basically, this design is dictated by the fact that we do not have a cheap way of doing in-place updates. This is a short version of the story. Here are some docs as well: http://www.linux-mtd.infradead.org/doc/ubifs.html#L_documentation -- Best Regards, Artem Bityutskiy