Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757374AbYJHAGU (ORCPT ); Tue, 7 Oct 2008 20:06:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752649AbYJHAGK (ORCPT ); Tue, 7 Oct 2008 20:06:10 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:55398 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751495AbYJHAGJ (ORCPT ); Tue, 7 Oct 2008 20:06:09 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Tejun Heo Cc: Al Viro , Benjamin Thery , Greg KH , linux-kernel@vger.kernel.org, "Serge E. Hallyn" , Al Viro , Linus Torvalds References: <48D7AC44.6050208@bull.net> <20080922153455.GA6238@kroah.com> <48D8FC1E.6000601@bull.net> <20081003101331.GH28946@ZenIV.linux.org.uk> <48EB27FE.2090009@kernel.org> <48EB53B8.5020309@kernel.org> <48EBEE0B.6080009@kernel.org> Date: Tue, 07 Oct 2008 17:04:15 -0700 In-Reply-To: <48EBEE0B.6080009@kernel.org> (Tejun Heo's message of "Wed, 08 Oct 2008 08:17:31 +0900") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=mx04.mta.xmission.com;;;ip=24.130.11.59;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 24.130.11.59 X-SA-Exim-Rcpt-To: too long (recipient list exceeded maximum allowed size of 128 bytes) X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Tejun Heo X-Spam-Relay-Country: X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -0.2 BAYES_40 BODY: Bayesian spam probability is 20 to 40% * [score: 0.2063] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 XM_SPF_Neutral SPF-Neutral Subject: Re: sysfs: tagged directories not merged completely yet X-SA-Exim-Version: 4.2.1 (built Thu, 07 Dec 2006 04:40:56 +0000) X-SA-Exim-Scanned: Yes (on mx04.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1540 Lines: 38 Tejun Heo writes: > Hello, a bit of additions after some sleep. > Heh... it did sound like a plan but I don't think the plan would solve > the problem. filldir can't be put in rcu read critical section. :-p There is srcu and there is the trick of grabbing the reference count on the current sysfs_dirent over the filldir and dropping the rcu lock (which works for proc). To cut down on lock overhead from user space accesses that works. >>> The revalidate on access model doesn't appear to have a way to track >>> remote renames. Something sysfs supports. >> >> Yeap, IIRC, one of the reasons why sysfs wasn't converted over to >> sysfs was because sysfs guarantees inode doesn't change over rename or >> move so that notifications keep working over renames. > > s/over to sysfs/over to revalidation/ and s/inode/dentry/. Maybe we can > just ignore dnotify? :-( Well there are more cases than dnotify, there is the renaming of directories in sysfs, although rare that I think get awkward if we use revalidation. I'm still not certain how we can get the lock ordering so it doesn't cause us problems. I will look at revalidation and what the other distributed filesystems are doing and see if that might work. If it doesn't we need refactor the VFS locking. Eric -- 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/