Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751418AbXE2S2T (ORCPT ); Tue, 29 May 2007 14:28:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750715AbXE2S2M (ORCPT ); Tue, 29 May 2007 14:28:12 -0400 Received: from rgminet01.oracle.com ([148.87.113.118]:39532 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750708AbXE2S2L (ORCPT ); Tue, 29 May 2007 14:28:11 -0400 Message-ID: <465C71EA.5040706@oracle.com> Date: Tue, 29 May 2007 11:33:14 -0700 From: Randy Dunlap User-Agent: Thunderbird 1.5.0.5 (X11/20060719) MIME-Version: 1.0 To: "Robert P. J. Day" CC: Andrew Morton , Linux Kernel Mailing List , Alexander Viro Subject: Re: [PATCH] FILESYSTEMS: Delete unused "int dummy[5]" from inodes_stat_t. References: <20070529110041.49bf57f1.akpm@linux-foundation.org> <20070529111902.27055fd0.randy.dunlap@oracle.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Whitelist: TRUE X-Whitelist: TRUE X-Brightmail-Tracker: AAAAAQAAAAI= Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2225 Lines: 59 Robert P. J. Day wrote: > On Tue, 29 May 2007, Randy Dunlap wrote: > >> On Tue, 29 May 2007 14:07:01 -0400 (EDT) Robert P. J. Day wrote: >> >>> On Tue, 29 May 2007, Andrew Morton wrote: >>> >>>> kernel/sysctl.c: >>>> >>>> { >>>> .ctl_name = FS_STATINODE, >>>> .procname = "inode-state", >>>> .data = &inodes_stat, >>>> .maxlen = 7*sizeof(int), <----- >>>> .mode = 0444, >>>> .proc_handler = &proc_dointvec, >>>> }, >>>> >>>> akpm:/home/akpm> cat /proc/sys/fs/inode-state >>>> 608039 178454 0 0 0 0 0 >>>> >>>> So it _is_ used: to present those five zeroes. I think this is >>>> for back-compatibility with some cretaceous-era kernel. >>> ah, gotcha. well, i'll leave this up to someone else to do >>> anything with if they are so inclined. >> There's little to be done, except possibly put a /* comment */ on >> the struct's dummy line so that we don't go thru this again in N >> years. > > so, just to clarify, what *is* the value of those trailing five > zeroes? andrew suggests it's to be backward-compatible with an old > kernel, which doesn't make much sense to me. it would make more sense > to say that that's backward-compatible with some old userspace app > that always wants to see seven values and just ignores the last five. Agreed, it's for compat with some (unknown) userspace app that reads /proc/sys/fs/inode-state and scans for 7 (or more than 2) numbers there. The mantra is "don't break userspace," so we leave the numbers there... > in any event, from Documentation/filesystems/proc.txt: > > "inode-state contains two actual numbers and five dummy values. The > numbers are nr_inodes and nr_free_inodes (in order of appearance)." > > if even the documentation calls them dummy values, do they really have > any residual value at this point? and on that note, i'll stop harping > on this and move on. > > rday -- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/