From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Righi Subject: [PATCH 4/9] support checking of cgroup subsystem dependencies Date: Tue, 14 Apr 2009 22:21:15 +0200 Message-ID: <1239740480-28125-5-git-send-email-righi.andrea__1254.7051570893$1239740738$gmane$org@gmail.com> References: <1239740480-28125-1-git-send-email-righi.andrea@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1239740480-28125-1-git-send-email-righi.andrea-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Paul Menage Cc: randy.dunlap-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, Carl Henrik Lunde , eric.rannaud-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Balbir Singh , fernando-gVGce1chcLdL9jVzuh4AOg@public.gmane.org, dradford-cT2on/YLNlBWk0Htik3J/w@public.gmane.org, agk-9JcytcrH/bA+uJoB2kUjGw@public.gmane.org, subrata-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, matt-cT2on/YLNlBWk0Htik3J/w@public.gmane.org, roberto-5KDOxZqKugI@public.gmane.org, ngupta-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org List-Id: containers.vger.kernel.org From: Li Zefan From: Li Zefan This allows one subsystem to require to be mounted only when some other subsystems are also present in or not in the proposed hierarchy. Signed-off-by: Li Zefan --- Documentation/cgroups/cgroups.txt | 5 +++++ include/linux/cgroup.h | 2 ++ kernel/cgroup.c | 19 ++++++++++++++++++- 3 files changed, 25 insertions(+), 1 deletions(-) diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index 6eb1a97..6938025 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -552,6 +552,11 @@ 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 665fa70..37ace23 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -385,6 +385,8 @@ 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); int subsys_id; int active; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 382109b..fad3f08 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -830,6 +830,23 @@ static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) 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; +} + struct cgroup_sb_opts { unsigned long subsys_bits; unsigned long flags; @@ -890,7 +907,7 @@ static int parse_cgroupfs_options(char *data, if (!opts->subsys_bits) return -EINVAL; - return 0; + return check_subsys_dependency(opts->subsys_bits); } static int cgroup_remount(struct super_block *sb, int *flags, char *data) -- 1.5.6.3