From patchwork Sat Aug 15 18:37:55 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 7021311 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id EDD49C05AC for ; Sat, 15 Aug 2015 18:44:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0B3FA206A3 for ; Sat, 15 Aug 2015 18:44:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2600E2069F for ; Sat, 15 Aug 2015 18:44:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754182AbbHOSos (ORCPT ); Sat, 15 Aug 2015 14:44:48 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:48566 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754089AbbHOSos (ORCPT ); Sat, 15 Aug 2015 14:44:48 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out03.mta.xmission.com with esmtps (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZQgRj-0006Kc-P4; Sat, 15 Aug 2015 12:44:47 -0600 Received: from 67-3-205-173.omah.qwest.net ([67.3.205.173] helo=x220.int.ebiederm.org.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZQgRi-00033a-KD; Sat, 15 Aug 2015 12:44:47 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Linux Containers Cc: linux-fsdevel@vger.kernel.org, Al Viro , Andy Lutomirski , "Serge E. Hallyn" , Richard Weinberger , Andrey Vagin , Jann Horn , Willy Tarreau , Omar Sandoval , Miklos Szeredi , Linus Torvalds , "J. Bruce Fields" References: <871tncuaf6.fsf@x220.int.ebiederm.org> <87mw5xq7lt.fsf@x220.int.ebiederm.org> <87a8yqou41.fsf_-_@x220.int.ebiederm.org> <874moq9oyb.fsf_-_@x220.int.ebiederm.org> <871tfkawu9.fsf_-_@x220.int.ebiederm.org> <87egjk9i61.fsf_-_@x220.int.ebiederm.org> <20150810043637.GC14139@ZenIV.linux.org.uk> <877foymrwt.fsf@x220.int.ebiederm.org> <87wpwyjxwc.fsf_-_@x220.int.ebiederm.org> <87fv3mjxsc.fsf_-_@x220.int.ebiederm.org> <20150815061617.GG14139@ZenIV.linux.org.uk> <874mk08l3g.fsf@x220.int.ebiederm.org> <87a8ts763c.fsf_-_@x220.int.ebiederm.org> Date: Sat, 15 Aug 2015 13:37:55 -0500 In-Reply-To: <87a8ts763c.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's message of "Sat, 15 Aug 2015 13:35:19 -0500") Message-ID: <87k2sw5rek.fsf_-_@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 X-XM-AID: U2FsdGVkX18S1wQdfIlsnbZc5rDNGanWwUadzQn4X2g= X-SA-Exim-Connect-IP: 67.3.205.173 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-DCC: XMission; sa02 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Linux Containers X-Spam-Relay-Country: X-Spam-Timing: total 563 ms - load_scoreonly_sql: 0.21 (0.0%), signal_user_changed: 5 (0.9%), b_tie_ro: 3.3 (0.6%), parse: 1.78 (0.3%), extract_message_metadata: 27 (4.8%), get_uri_detail_list: 2.8 (0.5%), tests_pri_-1000: 12 (2.0%), tests_pri_-950: 2.2 (0.4%), tests_pri_-900: 1.85 (0.3%), tests_pri_-400: 34 (6.1%), check_bayes: 32 (5.7%), b_tokenize: 13 (2.4%), b_tok_get_all: 7 (1.3%), b_comp_prob: 3.6 (0.6%), b_tok_touch_all: 3.5 (0.6%), b_finish: 0.93 (0.2%), tests_pri_0: 460 (81.7%), tests_pri_500: 12 (2.2%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH review 4/7] dcache: Implement d_common_ancestor X-SA-Exim-Version: 4.2.1 (built Wed, 24 Sep 2014 11:00:52 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If possible find the common ancestor of two dentries. This is necessary infrastructure for better handling the case when a dentry is moved out from under the root of a bind mount. Signed-off-by: "Eric W. Biederman" --- fs/dcache.c | 37 +++++++++++++++++++++++++++++++++++++ include/linux/dcache.h | 1 + 2 files changed, 38 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index 53b7f1e63beb..4e66bf92a481 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2469,6 +2469,43 @@ void dentry_update_name_case(struct dentry *dentry, struct qstr *name) } EXPORT_SYMBOL(dentry_update_name_case); +static unsigned long d_depth(const struct dentry *dentry) +{ + unsigned long depth = 0; + + while (!IS_ROOT(dentry)) { + dentry = dentry->d_parent; + depth++; + } + return depth; +} + +const struct dentry *d_common_ancestor(const struct dentry *left, + const struct dentry *right) +{ + unsigned long ldepth = d_depth(left); + unsigned long rdepth = d_depth(right); + + while (ldepth > rdepth) { + left = left->d_parent; + ldepth--; + } + + while (rdepth > ldepth) { + right = right->d_parent; + rdepth--; + } + + while (left != right) { + if (IS_ROOT(left)) + return NULL; + left = left->d_parent; + right = right->d_parent; + } + + return left; +} + static void swap_names(struct dentry *dentry, struct dentry *target) { if (unlikely(dname_external(target))) { diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 06bed2a1053c..5b69856b45a2 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -313,6 +313,7 @@ extern void dentry_update_name_case(struct dentry *, struct qstr *); extern void d_move(struct dentry *, struct dentry *); extern void d_exchange(struct dentry *, struct dentry *); extern struct dentry *d_ancestor(struct dentry *, struct dentry *); +extern const struct dentry *d_common_ancestor(const struct dentry *, const struct dentry *); /* appendix may either be NULL or be used for transname suffixes */ extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);