lkml.org 
[lkml]   [2008]   [Jun]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] cgroup: support checking of subsystem dependencies
On Wed, Jun 18, 2008 at 1:01 AM, Li Zefan <lizf@cn.fujitsu.com> wrote:
> 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 <lizf@cn.fujitsu.com>
> ---
> 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;
> +

Can we just call this from one place, in parse_cgroupfs_options() ?

Paul


\
 
 \ /
  Last update: 2008-06-18 23:17    [W:0.789 / U:0.260 seconds]
©2003-2014 Jasper Spaans. Advertise on this site