We will allow container to allocate new hierarchy,
and because the cgroup subsystems only can be linked
with one cgroupfs_root. so it's need to add a new field
top_root for cgroupfs_root to point out which subsystems
binds to this hierarchy.
Add a helper function find_top_root to help find out the
top_root.
also rename root_count to top_root_count.
Signed-off-by: Gao feng <gaofeng@xxxxxxxxxxxxxx>
---
kernel/cgroup.c | 29 ++++++++++++++++++++++++-----
1 files changed, 24 insertions(+), 5 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7d095b7..27ebeaf 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -132,6 +132,9 @@ struct cgroupfs_root {
/* The pid namespace this hierarchy belongs to */
struct pid_namespace *pid_ns;
+ /* The top root,subsystem only links with top root */
+ struct cgroupfs_root *top_root;
+
/* A list running through the active hierarchies */
struct list_head root_list;
@@ -234,7 +237,7 @@ struct cgroup_event {
/* The list of hierarchy roots */
static LIST_HEAD(roots);
-static int root_count;
+static int top_root_count;
static DEFINE_IDA(hierarchy_ida);
static int next_hierarchy_id;
@@ -682,7 +685,7 @@ static struct css_set *find_css_set(
return NULL;
/* Allocate all the cg_cgroup_link objects that we'll need */
- if (allocate_cg_links(root_count, &tmp_cg_links) < 0) {
+ if (allocate_cg_links(top_root_count, &tmp_cg_links) < 0) {
kfree(res);
return NULL;
}
@@ -847,6 +850,20 @@ static struct backing_dev_info cgroup_backing_dev_info = {
static int alloc_css_id(struct cgroup_subsys *ss,
struct cgroup *parent, struct cgroup *child);
+/*
+ * Find out the top root by subsys_mask.
+ */
+static struct cgroupfs_root *find_top_root(unsigned long subsys_mask)
+{
+ struct cgroupfs_root *existing_root;
+ for_each_active_root(existing_root) {
+ if (!test_bit(ROOT_NAMESPACE, &existing_root->flags) &&
+ existing_root->subsys_mask == subsys_mask)
+ return existing_root;
+ }
+ return NULL;
+}
+
static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
{
struct inode *inode = new_inode(sb);
@@ -1416,6 +1433,7 @@ static void init_cgroup_root(struct cgroupfs_root *root)
INIT_LIST_HEAD(&root->root_list);
INIT_LIST_HEAD(&root->allcg_list);
root->number_of_cgroups = 1;
+ root->top_root = root;
cgrp->root = root;
cgrp->top_cgroup = cgrp;
init_cgroup_housekeeping(cgrp);
@@ -1656,7 +1674,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
BUG_ON(ret);
list_add(&root->root_list, &roots);
- root_count++;
+ top_root_count++;
sb->s_root->d_fsdata = root_cgrp;
root->top_cgroup.dentry = sb->s_root;
@@ -1749,7 +1767,8 @@ static void cgroup_kill_sb(struct super_block *sb) {
if (!list_empty(&root->root_list)) {
list_del(&root->root_list);
- root_count--;
+ if (!test_bit(ROOT_NAMESPACE, &root->flags))
+ top_root_count--;
}
mutex_unlock(&cgroup_root_mutex);
@@ -4635,7 +4654,7 @@ int __init cgroup_init_early(void)
INIT_HLIST_NODE(&init_css_set.hlist);
css_set_count = 1;
init_cgroup_root(&rootnode);
- root_count = 1;
+ top_root_count = 1;
init_task.cgroups = &init_css_set;
init_css_set_link.cg = &init_css_set;
--
1.7.7.6
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