From: Li Zefan <lizf@xxxxxxxxxxxxxx>
From: Li Zefan <lizf@xxxxxxxxxxxxxx>
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 <lizf@xxxxxxxxxxxxxx>
---
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
_______________________________________________
Containers mailing list
Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/containers
