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cgroup: replace __DEVEL__sane_behavior with cgroup2 fs type

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With major controllers - cpu, memory and io - shaping up for the
unified hierarchy, cgroup2 is about ready to be, gradually, released
into the wild.  Replace __DEVEL__sane_behavior flag which was used to
select the unified hierarchy with a separate filesystem type "cgroup2"
so that unified hierarchy can be mounted as follows.

  mount -t cgroup2 none $MOUNT_POINT

The cgroup2 fs has its own magic number - 0x63677270 ("cgrp").

v2: Assign a different magic number to cgroup2 fs.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
This commit is contained in:
Tejun Heo 2015-11-16 11:13:34 -05:00
parent 34c06254ff
commit 67e9c74b8a
4 changed files with 26 additions and 29 deletions
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6
Documentation/cgroups/unified-hierarchy.txt
View File

@ -94,11 +94,9 @@ the process.
2-1. Mounting
Currently, unified hierarchy can be mounted with the following mount
command. Note that this is still under development and scheduled to
change soon.
Unified hierarchy can be mounted with the following mount command.
mount -t cgroup -o __DEVEL__sane_behavior cgroup $MOUNT_POINT
mount -t cgroup2 none $MOUNT_POINT
All controllers which support the unified hierarchy and are not bound
to other hierarchies are automatically bound to unified hierarchy and

1
include/linux/cgroup-defs.h
View File

@ -66,7 +66,6 @@ enum {
/* cgroup_root->flags */
enum {
CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
};

1
include/uapi/linux/magic.h
View File

@ -54,6 +54,7 @@
#define SMB_SUPER_MAGIC 0x517B
#define CGROUP_SUPER_MAGIC 0x27e0eb
#define CGROUP2_SUPER_MAGIC 0x63677270
#define STACK_END_MAGIC 0x57AC6E9D

47
kernel/cgroup.c
View File

@ -211,6 +211,7 @@ static unsigned long have_free_callback __read_mostly;
/* Ditto for the can_fork callback. */
static unsigned long have_canfork_callback __read_mostly;
static struct file_system_type cgroup2_fs_type;
static struct cftype cgroup_dfl_base_files[];
static struct cftype cgroup_legacy_base_files[];
@ -1641,10 +1642,6 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
all_ss = true;
continue;
}
if (!strcmp(token, "__DEVEL__sane_behavior")) {
opts->flags |= CGRP_ROOT_SANE_BEHAVIOR;
continue;
}
if (!strcmp(token, "noprefix")) {
opts->flags |= CGRP_ROOT_NOPREFIX;
continue;
@ -1711,15 +1708,6 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
return -ENOENT;
}
if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
if (nr_opts != 1) {
pr_err("sane_behavior: no other mount options allowed\n");
return -EINVAL;
}
return 0;
}
/*
* If the 'all' option was specified select all the subsystems,
* otherwise if 'none', 'name=' and a subsystem name options were
@ -1998,6 +1986,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
int flags, const char *unused_dev_name,
void *data)
{
bool is_v2 = fs_type == &cgroup2_fs_type;
struct super_block *pinned_sb = NULL;
struct cgroup_subsys *ss;
struct cgroup_root *root;
@ -2014,6 +2003,17 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
if (!use_task_css_set_links)
cgroup_enable_task_cg_lists();
if (is_v2) {
if (data) {
pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
return ERR_PTR(-EINVAL);
}
cgrp_dfl_root_visible = true;
root = &cgrp_dfl_root;
cgroup_get(&root->cgrp);
goto out_mount;
}
mutex_lock(&cgroup_mutex);
/* First find the desired set of subsystems */
@ -2021,15 +2021,6 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
if (ret)
goto out_unlock;
/* look for a matching existing root */
if (opts.flags & CGRP_ROOT_SANE_BEHAVIOR) {
cgrp_dfl_root_visible = true;
root = &cgrp_dfl_root;
cgroup_get(&root->cgrp);
ret = 0;
goto out_unlock;
}
/*
* Destruction of cgroup root is asynchronous, so subsystems may
* still be dying after the previous unmount. Let's drain the
@ -2140,9 +2131,10 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
if (ret)
return ERR_PTR(ret);
out_mount:
dentry = kernfs_mount(fs_type, flags, root->kf_root,
CGROUP_SUPER_MAGIC, &new_sb);
is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC,
&new_sb);
if (IS_ERR(dentry) || !new_sb)
cgroup_put(&root->cgrp);
@ -2185,6 +2177,12 @@ static struct file_system_type cgroup_fs_type = {
.kill_sb = cgroup_kill_sb,
};
static struct file_system_type cgroup2_fs_type = {
.name = "cgroup2",
.mount = cgroup_mount,
.kill_sb = cgroup_kill_sb,
};
/**
* task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
* @task: target task
@ -5315,6 +5313,7 @@ int __init cgroup_init(void)
WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
WARN_ON(register_filesystem(&cgroup_fs_type));
WARN_ON(register_filesystem(&cgroup2_fs_type));
WARN_ON(!proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations));
return 0;