Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751829AbYFRIEN (ORCPT ); Wed, 18 Jun 2008 04:04:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751179AbYFRIDt (ORCPT ); Wed, 18 Jun 2008 04:03:49 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:58020 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752202AbYFRIDj (ORCPT ); Wed, 18 Jun 2008 04:03:39 -0400 Message-ID: <4858C0ED.2080905@cn.fujitsu.com> Date: Wed, 18 Jun 2008 16:01:49 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Andrew Morton CC: Paul Menage , LKML , "containers@lists.osdl.org" , Balbir Singh , KAMEZAWA Hiroyuki , Paul Jackson Subject: [PATCH] cgroup: support checking of subsystem dependencies Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3319 Lines: 110 This allows one subsystem to require that it only be mounted when some other subsystems are also present in the proposed hierarchy. For example if subsystem foo depends on bar, the following will fail: # mount -t cgroup -ofoo xxx /dev/cgroup You should mount with both subsystems: # mount -t cgroup -ofoo,bar xxx /dev/cgroup Signed-off-by: Li Zefan --- Documentation/cgroups.txt | 6 ++++++ include/linux/cgroup.h | 2 ++ kernel/cgroup.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 38 insertions(+), 0 deletions(-) diff --git a/Documentation/cgroups.txt b/Documentation/cgroups.txt index 824fc02..8252f5b 100644 --- a/Documentation/cgroups.txt +++ b/Documentation/cgroups.txt @@ -530,6 +530,12 @@ and root cgroup. Currently this will only involve movement between the default hierarchy (which never has sub-cgroups) and a hierarchy that is being created/destroyed (and hence has no sub-cgroups). +int subsys_depend(struct cgroup_subsys *ss, unsigned long subsys_bits) + +Called when a cgroup subsystem wants to check if some other subsystems +are also present in the proposed hierarchy. If this method returns error, +the mount of the cgroup filesystem will fail. + 4. Questions ============ diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index e155aa7..fc99ba4 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -305,6 +305,8 @@ struct cgroup_subsys { struct cgroup *cgrp); void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); + int (*subsys_depend)(struct cgroup_subsys *ss, + unsigned long subsys_bits); /* * This routine is called with the task_lock of mm->owner held */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 15ac0e1..a4c8671 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -837,6 +837,25 @@ static int parse_cgroupfs_options(char *data, return 0; } +static int check_subsys_dependency(unsigned long subsys_bits) +{ + int i; + int ret; + struct cgroup_subsys *ss; + + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { + ss = subsys[i]; + + if (test_bit(i, &subsys_bits) && ss->subsys_depend) { + ret = ss->subsys_depend(ss, subsys_bits); + if (ret) + return ret; + } + } + + return 0; +} + static int cgroup_remount(struct super_block *sb, int *flags, char *data) { int ret = 0; @@ -852,6 +871,10 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) if (ret) goto out_unlock; + ret = check_subsys_dependency(opts.subsys_bits); + if (ret) + goto out_unlock; + /* Don't allow flags to change at remount */ if (opts.flags != root->flags) { ret = -EINVAL; @@ -972,6 +995,13 @@ static int cgroup_get_sb(struct file_system_type *fs_type, return ret; } + ret = check_subsys_dependency(opts.subsys_bits); + if (ret) { + if (opts.release_agent) + kfree(opts.release_agent); + return ret; + } + root = kzalloc(sizeof(*root), GFP_KERNEL); if (!root) { if (opts.release_agent) -- 1.5.4.rc3 -- 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/