Messages in this thread Patch in this message | | | Date | Thu, 20 Nov 2008 19:14:57 +0800 | From | Gui Jianfeng <> | Subject | [PATCH 6/7] support checking of subsystem dependencies |
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From: Li Zefan <lizf@cn.fujitsu.com>
This allows one subsystem to require that it only be mounted when some other subsystems are also present in or not in the proposed hierarchy.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> --- Documentation/cgroups/cgroups.txt | 5 +++++ include/linux/cgroup.h | 2 ++ kernel/cgroup.c | 21 ++++++++++++++++++++- 3 files changed, 27 insertions(+), 1 deletions(-)
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index d9014aa..df648c6 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -534,6 +534,11 @@ 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 1164963..1899449 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -329,6 +329,8 @@ 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 a512a75..8a07023 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -761,6 +761,25 @@ 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; @@ -821,7 +840,7 @@ 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) -- 1.5.4.rc3
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