From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754786AbcI0N23 (ORCPT ); Tue, 27 Sep 2016 09:28:29 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:36214 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754421AbcI0N2Q (ORCPT ); Tue, 27 Sep 2016 09:28:16 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Ian Kent Cc: Mateusz Guzik , NeilBrown , Andrew Morton , autofs mailing list , Kernel Mailing List , Al Viro , linux-fsdevel , Omar Sandoval References: <20160914061434.24714.490.stgit@pluto.themaw.net> <20160914061445.24714.68331.stgit@pluto.themaw.net> <20160917201000.omswgttgyzcu7jt6@mguzik> <1474248973.3204.14.camel@themaw.net> <87oa3iikgf.fsf@x220.int.ebiederm.org> <1474411462.22440.2.camel@themaw.net> <1474412413.22440.7.camel@themaw.net> <1474507987.12887.5.camel@themaw.net> <87k2e4c541.fsf@x220.int.ebiederm.org> <1474592141.3345.20.camel@themaw.net> <877fa39z1q.fsf@x220.int.ebiederm.org> <1474604774.3083.1.camel@themaw.net> <87oa3e8m2v.fsf@x220.int.ebiederm.org> <1474675869.3078.3.camel@themaw.net> <878tue8x4s.fsf@x220.int.ebiederm.org> <1474941132.3390.6.camel@themaw.net> Date: Tue, 27 Sep 2016 08:14:27 -0500 In-Reply-To: <1474941132.3390.6.camel@themaw.net> (Ian Kent's message of "Tue, 27 Sep 2016 09:52:12 +0800") Message-ID: <871t057ado.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1bosQe-0001Ok-Uj;;;mid=<871t057ado.fsf@x220.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=75.170.125.99;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+GbUlM+jpCGMdGlB57DQvcEy6Bj7b0an0= X-SA-Exim-Connect-IP: 75.170.125.99 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 TVD_RCVD_IP Message was received from an IP address * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.7 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.4998] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa04 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa04 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **;Ian Kent X-Spam-Relay-Country: X-Spam-Timing: total 580 ms - load_scoreonly_sql: 0.05 (0.0%), signal_user_changed: 4.4 (0.8%), b_tie_ro: 3.0 (0.5%), parse: 1.40 (0.2%), extract_message_metadata: 14 (2.5%), get_uri_detail_list: 3.1 (0.5%), tests_pri_-1000: 4.7 (0.8%), tests_pri_-950: 1.13 (0.2%), tests_pri_-900: 0.91 (0.2%), tests_pri_-400: 31 (5.3%), check_bayes: 29 (5.0%), b_tokenize: 7 (1.2%), b_tok_get_all: 11 (2.0%), b_comp_prob: 4.1 (0.7%), b_tok_touch_all: 3.6 (0.6%), b_finish: 1.01 (0.2%), tests_pri_0: 515 (88.7%), check_dkim_signature: 0.50 (0.1%), check_dkim_adsp: 4.0 (0.7%), tests_pri_500: 4.0 (0.7%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH 3/4] autofs - make mountpoint checks namespace aware X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ian Kent writes: > On Mon, 2016-09-26 at 11:05 -0500, Eric W. Biederman wrote: >> Ian Kent writes: >> >> > On Fri, 2016-09-23 at 14:15 -0500, Eric W. Biederman wrote: >> > > Ian Kent writes: >> > > >> > > 2> On Thu, 2016-09-22 at 20:37 -0500, Eric W. Biederman wrote: >> > > > > Ian Kent writes: >> > > > > >> > > > > > On Thu, 2016-09-22 at 10:43 -0500, Eric W. Biederman wrote: >> > > > > > > Ian Kent writes: >> > > > > > > >> > > > > > > > Eric, Mateusz, I appreciate your spending time on this and >> > > > > > > > particularly >> > > > > > > > pointing >> > > > > > > > out my embarrassingly stupid is_local_mountpoint() usage >> > > > > > > > mistake. >> > > > > > > > >> > > > > > > > Please accept my apology for the inconvenience. >> > > > > > > > >> > > > > > > > If all goes well (in testing) I'll have follow up patches to >> > > > > > > > correct >> > > > > > > > this >> > > > > > > > fairly >> > > > > > > > soon. >> > > > > > > >> > > > > > > Related question. Do you happen to know how many mounts per mount >> > > > > > > namespace tend to be used? It looks like it is going to be wise >> > > > > > > to >> > > > > > > put >> > > > > > > a configurable limit on that number. And I would like the default >> > > > > > > to >> > > > > > > be >> > > > > > > something high enough most people don't care. I believe autofs is >> > > > > > > likely where people tend to use the most mounts. >> > > > >> > > > Yes, I agree, I did want to try and avoid changing the parameters to >> > > > ->d_mamange() but passing a struct path pointer might be better in the >> > > > long >> > > > run >> > > > anyway. >> > > >> > > Given that there is exactly one implementation of d_manage in the tree I >> > > don't imagine it will be disruptive to change that. >> > >> > Yes, but it could be used by external modules. >> > >> > And there's also have_submounts(). >> >> Good point about have_submounts. >> >> > I can update that using the existing d_walk() infrastructure or take it >> > (mostly) >> > into the autofs module and get rid of have_submounts(). >> > >> > I'll go with the former to start with and see what people think. >> >> That will be interesting to so. It is not clear to me that if d_walk >> needs to be updated, and if d_walk doesn't need to be updated I would >> be surprised to see it take into autofs. But I am happy to look at the >> end result and see what you come up with. > > I didn't mean d_walk() itself, just the have_submounts() function that's used > only by autofs these days. That's all I'll be changing. > > To take this functionality into the autofs module shouldn't be a big deal as it > amounts to a directory traversal with a check at each node. > > But I vaguely remember talk of wanting to get rid of have_submounts() and autofs > being the only remaining user. > > So I mentioned it to try and elicit a comment, ;) >>From my perspective the key detail is that d_walk is private to dcache.c That said you want to look at may_umount_tree, or may_umount that are already exported from fs/namespace.c, and already used by autofs. One of those may already do the job you are trying to do. It looks like at least may_umount needs to be examined to see if it does the right thing for the tweaked semantics of autofs. Eric