cgroup: move v1 mount functions to kernel/cgroup/cgroup-v1.c

Now that the v1 mount code is split into separate functions, move them
to kernel/cgroup/cgroup-v1.c along with the mount option handling
code.  As this puts all v1-only kernfs_syscall_ops in cgroup-v1.c,
move cgroup1_kf_syscall_ops to cgroup-v1.c too.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Acked-by: Zefan Li <lizefan@huawei.com>

3 files changed, 413 insertions, 406 deletions

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 5790e5ff9a0f..710edeeb1f9f 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -26,6 +26,16 @@ struct cgrp_cset_link {
         struct list_head        cgrp_link;
 };
 
+struct cgroup_sb_opts {
+        u16 subsys_mask;
+        unsigned int flags;
+        char *release_agent;
+        bool cpuset_clone_children;
+        char *name;
+        /* User explicitly requested empty subsystem */
+        bool none;
+};
+
 extern struct mutex cgroup_mutex;
 extern spinlock_t css_set_lock;
 extern struct cgroup_subsys *cgroup_subsys[];
@@ -66,7 +76,13 @@ void cgroup_kn_unlock(struct kernfs_node *kn);
 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
                           struct cgroup_namespace *ns);
 
+void cgroup_free_root(struct cgroup_root *root);
+void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);
+int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);
 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
+struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
+                               struct cgroup_root *root, unsigned long magic,
+                               struct cgroup_namespace *ns);
 
 bool cgroup_may_migrate_to(struct cgroup *dst_cgrp);
 void cgroup_migrate_finish(struct list_head *preloaded_csets);
@@ -86,18 +102,24 @@ ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes
 
 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 
+int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
+int cgroup_rmdir(struct kernfs_node *kn);
+int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+                     struct kernfs_root *kf_root);
+
 /*
  * cgroup-v1.c
  */
-extern spinlock_t release_agent_path_lock;
 extern struct cftype cgroup_legacy_base_files[];
 extern const struct file_operations proc_cgroupstats_operations;
+extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 
 bool cgroup_ssid_no_v1(int ssid);
 void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
-int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-                   const char *new_name_str);
 void cgroup_release_agent(struct work_struct *work);
 void check_for_release(struct cgroup *cgrp);
+struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
+                             void *data, unsigned long magic,
+                             struct cgroup_namespace *ns);
 
 #endif /* __CGROUP_INTERNAL_H */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 0b2c24f0b310..ae240c0d33cb 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -1,7 +1,9 @@
 #include "cgroup-internal.h"
 
+#include <linux/ctype.h>
 #include <linux/kmod.h>
 #include <linux/sort.h>
+#include <linux/delay.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
@@ -32,7 +34,7 @@ static struct workqueue_struct *cgroup_pidlist_destroy_wq;
  * Protects cgroup_subsys->release_agent_path.  Modifying it also requires
  * cgroup_mutex.  Reading requires either cgroup_mutex or this spinlock.
  */
-DEFINE_SPINLOCK(release_agent_path_lock);
+static DEFINE_SPINLOCK(release_agent_path_lock);
 
 bool cgroup_ssid_no_v1(int ssid)
 {
@@ -800,8 +802,8 @@ out_free:
 /*
  * cgroup_rename - Only allow simple rename of directories in place.
  */
-int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-                   const char *new_name_str)
+static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+                          const char *new_name_str)
 {
         struct cgroup *cgrp = kn->priv;
         int ret;
@@ -832,6 +834,379 @@ int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
         return ret;
 }
 
+static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
+{
+        struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+        struct cgroup_subsys *ss;
+        int ssid;
+
+        for_each_subsys(ss, ssid)
+                if (root->subsys_mask & (1 << ssid))
+                        seq_show_option(seq, ss->legacy_name, NULL);
+        if (root->flags & CGRP_ROOT_NOPREFIX)
+                seq_puts(seq, ",noprefix");
+        if (root->flags & CGRP_ROOT_XATTR)
+                seq_puts(seq, ",xattr");
+
+        spin_lock(&release_agent_path_lock);
+        if (strlen(root->release_agent_path))
+                seq_show_option(seq, "release_agent",
+                                root->release_agent_path);
+        spin_unlock(&release_agent_path_lock);
+
+        if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
+                seq_puts(seq, ",clone_children");
+        if (strlen(root->name))
+                seq_show_option(seq, "name", root->name);
+        return 0;
+}
+
+static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
+{
+        char *token, *o = data;
+        bool all_ss = false, one_ss = false;
+        u16 mask = U16_MAX;
+        struct cgroup_subsys *ss;
+        int nr_opts = 0;
+        int i;
+
+#ifdef CONFIG_CPUSETS
+        mask = ~((u16)1 << cpuset_cgrp_id);
+#endif
+
+        memset(opts, 0, sizeof(*opts));
+
+        while ((token = strsep(&o, ",")) != NULL) {
+                nr_opts++;
+
+                if (!*token)
+                        return -EINVAL;
+                if (!strcmp(token, "none")) {
+                        /* Explicitly have no subsystems */
+                        opts->none = true;
+                        continue;
+                }
+                if (!strcmp(token, "all")) {
+                        /* Mutually exclusive option 'all' + subsystem name */
+                        if (one_ss)
+                                return -EINVAL;
+                        all_ss = true;
+                        continue;
+                }
+                if (!strcmp(token, "noprefix")) {
+                        opts->flags |= CGRP_ROOT_NOPREFIX;
+                        continue;
+                }
+                if (!strcmp(token, "clone_children")) {
+                        opts->cpuset_clone_children = true;
+                        continue;
+                }
+                if (!strcmp(token, "xattr")) {
+                        opts->flags |= CGRP_ROOT_XATTR;
+                        continue;
+                }
+                if (!strncmp(token, "release_agent=", 14)) {
+                        /* Specifying two release agents is forbidden */
+                        if (opts->release_agent)
+                                return -EINVAL;
+                        opts->release_agent =
+                                kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
+                        if (!opts->release_agent)
+                                return -ENOMEM;
+                        continue;
+                }
+                if (!strncmp(token, "name=", 5)) {
+                        const char *name = token + 5;
+                        /* Can't specify an empty name */
+                        if (!strlen(name))
+                                return -EINVAL;
+                        /* Must match [\w.-]+ */
+                        for (i = 0; i < strlen(name); i++) {
+                                char c = name[i];
+                                if (isalnum(c))
+                                        continue;
+                                if ((c == '.') || (c == '-') || (c == '_'))
+                                        continue;
+                                return -EINVAL;
+                        }
+                        /* Specifying two names is forbidden */
+                        if (opts->name)
+                                return -EINVAL;
+                        opts->name = kstrndup(name,
+                                              MAX_CGROUP_ROOT_NAMELEN - 1,
+                                              GFP_KERNEL);
+                        if (!opts->name)
+                                return -ENOMEM;
+
+                        continue;
+                }
+
+                for_each_subsys(ss, i) {
+                        if (strcmp(token, ss->legacy_name))
+                                continue;
+                        if (!cgroup_ssid_enabled(i))
+                                continue;
+                        if (cgroup_ssid_no_v1(i))
+                                continue;
+
+                        /* Mutually exclusive option 'all' + subsystem name */
+                        if (all_ss)
+                                return -EINVAL;
+                        opts->subsys_mask |= (1 << i);
+                        one_ss = true;
+
+                        break;
+                }
+                if (i == CGROUP_SUBSYS_COUNT)
+                        return -ENOENT;
+        }
+
+        /*
+         * If the 'all' option was specified select all the subsystems,
+         * otherwise if 'none', 'name=' and a subsystem name options were
+         * not specified, let's default to 'all'
+         */
+        if (all_ss || (!one_ss && !opts->none && !opts->name))
+                for_each_subsys(ss, i)
+                        if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
+                                opts->subsys_mask |= (1 << i);
+
+        /*
+         * We either have to specify by name or by subsystems. (So all
+         * empty hierarchies must have a name).
+         */
+        if (!opts->subsys_mask && !opts->name)
+                return -EINVAL;
+
+        /*
+         * Option noprefix was introduced just for backward compatibility
+         * with the old cpuset, so we allow noprefix only if mounting just
+         * the cpuset subsystem.
+         */
+        if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
+                return -EINVAL;
+
+        /* Can't specify "none" and some subsystems */
+        if (opts->subsys_mask && opts->none)
+                return -EINVAL;
+
+        return 0;
+}
+
+static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
+{
+        int ret = 0;
+        struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+        struct cgroup_sb_opts opts;
+        u16 added_mask, removed_mask;
+
+        cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+        /* See what subsystems are wanted */
+        ret = parse_cgroupfs_options(data, &opts);
+        if (ret)
+                goto out_unlock;
+
+        if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
+                pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
+                        task_tgid_nr(current), current->comm);
+
+        added_mask = opts.subsys_mask & ~root->subsys_mask;
+        removed_mask = root->subsys_mask & ~opts.subsys_mask;
+
+        /* Don't allow flags or name to change at remount */
+        if ((opts.flags ^ root->flags) ||
+            (opts.name && strcmp(opts.name, root->name))) {
+                pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
+                       opts.flags, opts.name ?: "", root->flags, root->name);
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+
+        /* remounting is not allowed for populated hierarchies */
+        if (!list_empty(&root->cgrp.self.children)) {
+                ret = -EBUSY;
+                goto out_unlock;
+        }
+
+        ret = rebind_subsystems(root, added_mask);
+        if (ret)
+                goto out_unlock;
+
+        WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
+
+        if (opts.release_agent) {
+                spin_lock(&release_agent_path_lock);
+                strcpy(root->release_agent_path, opts.release_agent);
+                spin_unlock(&release_agent_path_lock);
+        }
+
+        trace_cgroup_remount(root);
+
+ out_unlock:
+        kfree(opts.release_agent);
+        kfree(opts.name);
+        mutex_unlock(&cgroup_mutex);
+        return ret;
+}
+
+struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
+        .rename                 = cgroup1_rename,
+        .show_options           = cgroup1_show_options,
+        .remount_fs             = cgroup1_remount,
+        .mkdir                  = cgroup_mkdir,
+        .rmdir                  = cgroup_rmdir,
+        .show_path              = cgroup_show_path,
+};
+
+struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
+                             void *data, unsigned long magic,
+                             struct cgroup_namespace *ns)
+{
+        struct super_block *pinned_sb = NULL;
+        struct cgroup_sb_opts opts;
+        struct cgroup_root *root;
+        struct cgroup_subsys *ss;
+        struct dentry *dentry;
+        int i, ret;
+
+        cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+        /* First find the desired set of subsystems */
+        ret = parse_cgroupfs_options(data, &opts);
+        if (ret)
+                goto out_unlock;
+
+        /*
+         * Destruction of cgroup root is asynchronous, so subsystems may
+         * still be dying after the previous unmount.  Let's drain the
+         * dying subsystems.  We just need to ensure that the ones
+         * unmounted previously finish dying and don't care about new ones
+         * starting.  Testing ref liveliness is good enough.
+         */
+        for_each_subsys(ss, i) {
+                if (!(opts.subsys_mask & (1 << i)) ||
+                    ss->root == &cgrp_dfl_root)
+                        continue;
+
+                if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
+                        mutex_unlock(&cgroup_mutex);
+                        msleep(10);
+                        ret = restart_syscall();
+                        goto out_free;
+                }
+                cgroup_put(&ss->root->cgrp);
+        }
+
+        for_each_root(root) {
+                bool name_match = false;
+
+                if (root == &cgrp_dfl_root)
+                        continue;
+
+                /*
+                 * If we asked for a name then it must match.  Also, if
+                 * name matches but sybsys_mask doesn't, we should fail.
+                 * Remember whether name matched.
+                 */
+                if (opts.name) {
+                        if (strcmp(opts.name, root->name))
+                                continue;
+                        name_match = true;
+                }
+
+                /*
+                 * If we asked for subsystems (or explicitly for no
+                 * subsystems) then they must match.
+                 */
+                if ((opts.subsys_mask || opts.none) &&
+                    (opts.subsys_mask != root->subsys_mask)) {
+                        if (!name_match)
+                                continue;
+                        ret = -EBUSY;
+                        goto out_unlock;
+                }
+
+                if (root->flags ^ opts.flags)
+                        pr_warn("new mount options do not match the existing superblock, will be ignored\n");
+
+                /*
+                 * We want to reuse @root whose lifetime is governed by its
+                 * ->cgrp.  Let's check whether @root is alive and keep it
+                 * that way.  As cgroup_kill_sb() can happen anytime, we
+                 * want to block it by pinning the sb so that @root doesn't
+                 * get killed before mount is complete.
+                 *
+                 * With the sb pinned, tryget_live can reliably indicate
+                 * whether @root can be reused.  If it's being killed,
+                 * drain it.  We can use wait_queue for the wait but this
+                 * path is super cold.  Let's just sleep a bit and retry.
+                 */
+                pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
+                if (IS_ERR(pinned_sb) ||
+                    !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
+                        mutex_unlock(&cgroup_mutex);
+                        if (!IS_ERR_OR_NULL(pinned_sb))
+                                deactivate_super(pinned_sb);
+                        msleep(10);
+                        ret = restart_syscall();
+                        goto out_free;
+                }
+
+                ret = 0;
+                goto out_unlock;
+        }
+
+        /*
+         * No such thing, create a new one.  name= matching without subsys
+         * specification is allowed for already existing hierarchies but we
+         * can't create new one without subsys specification.
+         */
+        if (!opts.subsys_mask && !opts.none) {
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+
+        /* Hierarchies may only be created in the initial cgroup namespace. */
+        if (ns != &init_cgroup_ns) {
+                ret = -EPERM;
+                goto out_unlock;
+        }
+
+        root = kzalloc(sizeof(*root), GFP_KERNEL);
+        if (!root) {
+                ret = -ENOMEM;
+                goto out_unlock;
+        }
+
+        init_cgroup_root(root, &opts);
+
+        ret = cgroup_setup_root(root, opts.subsys_mask);
+        if (ret)
+                cgroup_free_root(root);
+
+out_unlock:
+        mutex_unlock(&cgroup_mutex);
+out_free:
+        kfree(opts.release_agent);
+        kfree(opts.name);
+
+        if (ret)
+                return ERR_PTR(ret);
+
+        dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
+                                 CGROUP_SUPER_MAGIC, ns);
+
+        /*
+         * If @pinned_sb, we're reusing an existing root and holding an
+         * extra ref on its sb.  Mount is complete.  Put the extra ref.
+         */
+        if (pinned_sb)
+                deactivate_super(pinned_sb);
+
+        return dentry;
+}
+
 static int __init cgroup1_wq_init(void)
 {
         /*
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index de6a2ac41d0b..4be306510aff 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -31,7 +31,6 @@
 #include "cgroup-internal.h"
 
 #include <linux/cred.h>
-#include <linux/ctype.h>
 #include <linux/errno.h>
 #include <linux/init_task.h>
 #include <linux/kernel.h>
@@ -49,7 +48,6 @@
 #include <linux/hashtable.h>
 #include <linux/idr.h>
 #include <linux/kthread.h>
-#include <linux/delay.h>
 #include <linux/atomic.h>
 #include <linux/cpuset.h>
 #include <linux/proc_ns.h>
@@ -1078,7 +1076,7 @@ static void cgroup_exit_root_id(struct cgroup_root *root)
         idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
 }
 
-static void cgroup_free_root(struct cgroup_root *root)
+void cgroup_free_root(struct cgroup_root *root)
 {
         if (root) {
                 idr_destroy(&root->cgroup_idr);
@@ -1232,7 +1230,6 @@ struct cgroup *task_cgroup_from_root(struct task_struct *task,
  * update of a tasks cgroup pointer by cgroup_attach_task()
  */
 
-static struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
 
 static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
@@ -1540,8 +1537,8 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
         return 0;
 }
 
-static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
-                            struct kernfs_root *kf_root)
+int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+                     struct kernfs_root *kf_root)
 {
         int len = 0;
         char *buf = NULL;
@@ -1567,232 +1564,6 @@ static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
         return len;
 }
 
-static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
-{
-        struct cgroup_root *root = cgroup_root_from_kf(kf_root);
-        struct cgroup_subsys *ss;
-        int ssid;
-
-        for_each_subsys(ss, ssid)
-                if (root->subsys_mask & (1 << ssid))
-                        seq_show_option(seq, ss->legacy_name, NULL);
-        if (root->flags & CGRP_ROOT_NOPREFIX)
-                seq_puts(seq, ",noprefix");
-        if (root->flags & CGRP_ROOT_XATTR)
-                seq_puts(seq, ",xattr");
-
-        spin_lock(&release_agent_path_lock);
-        if (strlen(root->release_agent_path))
-                seq_show_option(seq, "release_agent",
-                                root->release_agent_path);
-        spin_unlock(&release_agent_path_lock);
-
-        if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
-                seq_puts(seq, ",clone_children");
-        if (strlen(root->name))
-                seq_show_option(seq, "name", root->name);
-        return 0;
-}
-
-struct cgroup_sb_opts {
-        u16 subsys_mask;
-        unsigned int flags;
-        char *release_agent;
-        bool cpuset_clone_children;
-        char *name;
-        /* User explicitly requested empty subsystem */
-        bool none;
-};
-
-static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
-{
-        char *token, *o = data;
-        bool all_ss = false, one_ss = false;
-        u16 mask = U16_MAX;
-        struct cgroup_subsys *ss;
-        int nr_opts = 0;
-        int i;
-
-#ifdef CONFIG_CPUSETS
-        mask = ~((u16)1 << cpuset_cgrp_id);
-#endif
-
-        memset(opts, 0, sizeof(*opts));
-
-        while ((token = strsep(&o, ",")) != NULL) {
-                nr_opts++;
-
-                if (!*token)
-                        return -EINVAL;
-                if (!strcmp(token, "none")) {
-                        /* Explicitly have no subsystems */
-                        opts->none = true;
-                        continue;
-                }
-                if (!strcmp(token, "all")) {
-                        /* Mutually exclusive option 'all' + subsystem name */
-                        if (one_ss)
-                                return -EINVAL;
-                        all_ss = true;
-                        continue;
-                }
-                if (!strcmp(token, "noprefix")) {
-                        opts->flags |= CGRP_ROOT_NOPREFIX;
-                        continue;
-                }
-                if (!strcmp(token, "clone_children")) {
-                        opts->cpuset_clone_children = true;
-                        continue;
-                }
-                if (!strcmp(token, "xattr")) {
-                        opts->flags |= CGRP_ROOT_XATTR;
-                        continue;
-                }
-                if (!strncmp(token, "release_agent=", 14)) {
-                        /* Specifying two release agents is forbidden */
-                        if (opts->release_agent)
-                                return -EINVAL;
-                        opts->release_agent =
-                                kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
-                        if (!opts->release_agent)
-                                return -ENOMEM;
-                        continue;
-                }
-                if (!strncmp(token, "name=", 5)) {
-                        const char *name = token + 5;
-                        /* Can't specify an empty name */
-                        if (!strlen(name))
-                                return -EINVAL;
-                        /* Must match [\w.-]+ */
-                        for (i = 0; i < strlen(name); i++) {
-                                char c = name[i];
-                                if (isalnum(c))
-                                        continue;
-                                if ((c == '.') || (c == '-') || (c == '_'))
-                                        continue;
-                                return -EINVAL;
-                        }
-                        /* Specifying two names is forbidden */
-                        if (opts->name)
-                                return -EINVAL;
-                        opts->name = kstrndup(name,
-                                              MAX_CGROUP_ROOT_NAMELEN - 1,
-                                              GFP_KERNEL);
-                        if (!opts->name)
-                                return -ENOMEM;
-
-                        continue;
-                }
-
-                for_each_subsys(ss, i) {
-                        if (strcmp(token, ss->legacy_name))
-                                continue;
-                        if (!cgroup_ssid_enabled(i))
-                                continue;
-                        if (cgroup_ssid_no_v1(i))
-                                continue;
-
-                        /* Mutually exclusive option 'all' + subsystem name */
-                        if (all_ss)
-                                return -EINVAL;
-                        opts->subsys_mask |= (1 << i);
-                        one_ss = true;
-
-                        break;
-                }
-                if (i == CGROUP_SUBSYS_COUNT)
-                        return -ENOENT;
-        }
-
-        /*
-         * If the 'all' option was specified select all the subsystems,
-         * otherwise if 'none', 'name=' and a subsystem name options were
-         * not specified, let's default to 'all'
-         */
-        if (all_ss || (!one_ss && !opts->none && !opts->name))
-                for_each_subsys(ss, i)
-                        if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
-                                opts->subsys_mask |= (1 << i);
-
-        /*
-         * We either have to specify by name or by subsystems. (So all
-         * empty hierarchies must have a name).
-         */
-        if (!opts->subsys_mask && !opts->name)
-                return -EINVAL;
-
-        /*
-         * Option noprefix was introduced just for backward compatibility
-         * with the old cpuset, so we allow noprefix only if mounting just
-         * the cpuset subsystem.
-         */
-        if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
-                return -EINVAL;
-
-        /* Can't specify "none" and some subsystems */
-        if (opts->subsys_mask && opts->none)
-                return -EINVAL;
-
-        return 0;
-}
-
-static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
-{
-        int ret = 0;
-        struct cgroup_root *root = cgroup_root_from_kf(kf_root);
-        struct cgroup_sb_opts opts;
-        u16 added_mask, removed_mask;
-
-        cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
-
-        /* See what subsystems are wanted */
-        ret = parse_cgroupfs_options(data, &opts);
-        if (ret)
-                goto out_unlock;
-
-        if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
-                pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
-                        task_tgid_nr(current), current->comm);
-
-        added_mask = opts.subsys_mask & ~root->subsys_mask;
-        removed_mask = root->subsys_mask & ~opts.subsys_mask;
-
-        /* Don't allow flags or name to change at remount */
-        if ((opts.flags ^ root->flags) ||
-            (opts.name && strcmp(opts.name, root->name))) {
-                pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
-                       opts.flags, opts.name ?: "", root->flags, root->name);
-                ret = -EINVAL;
-                goto out_unlock;
-        }
-
-        /* remounting is not allowed for populated hierarchies */
-        if (!list_empty(&root->cgrp.self.children)) {
-                ret = -EBUSY;
-                goto out_unlock;
-        }
-
-        ret = rebind_subsystems(root, added_mask);
-        if (ret)
-                goto out_unlock;
-
-        WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
-
-        if (opts.release_agent) {
-                spin_lock(&release_agent_path_lock);
-                strcpy(root->release_agent_path, opts.release_agent);
-                spin_unlock(&release_agent_path_lock);
-        }
-
-        trace_cgroup_remount(root);
-
- out_unlock:
-        kfree(opts.release_agent);
-        kfree(opts.name);
-        mutex_unlock(&cgroup_mutex);
-        return ret;
-}
-
 static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
 {
         pr_err("remount is not allowed\n");
@@ -1877,8 +1648,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
         INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
 }
 
-static void init_cgroup_root(struct cgroup_root *root,
-                             struct cgroup_sb_opts *opts)
+void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts)
 {
         struct cgroup *cgrp = &root->cgrp;
 
@@ -1897,7 +1667,7 @@ static void init_cgroup_root(struct cgroup_root *root,
                 set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
 }
 
-static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
+int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 {
         LIST_HEAD(tmp_links);
         struct cgroup *root_cgrp = &root->cgrp;
@@ -1994,10 +1764,9 @@ out:
         return ret;
 }
 
-static struct dentry *cgroup_do_mount(struct file_system_type *fs_type,
-                                      int flags, struct cgroup_root *root,
-                                      unsigned long magic,
-                                      struct cgroup_namespace *ns)
+struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
+                               struct cgroup_root *root, unsigned long magic,
+                               struct cgroup_namespace *ns)
 {
         struct dentry *dentry;
         bool new_sb;
@@ -2031,155 +1800,6 @@ static struct dentry *cgroup_do_mount(struct file_system_type *fs_type,
         return dentry;
 }
 
-static struct dentry *cgroup1_mount(struct file_system_type *fs_type,
-                                    int flags, void *data,
-                                    unsigned long magic,
-                                    struct cgroup_namespace *ns)
-{
-        struct super_block *pinned_sb = NULL;
-        struct cgroup_sb_opts opts;
-        struct cgroup_root *root;
-        struct cgroup_subsys *ss;
-        struct dentry *dentry;
-        int i, ret;
-
-        cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
-
-        /* First find the desired set of subsystems */
-        ret = parse_cgroupfs_options(data, &opts);
-        if (ret)
-                goto out_unlock;
-
-        /*
-         * Destruction of cgroup root is asynchronous, so subsystems may
-         * still be dying after the previous unmount.  Let's drain the
-         * dying subsystems.  We just need to ensure that the ones
-         * unmounted previously finish dying and don't care about new ones
-         * starting.  Testing ref liveliness is good enough.
-         */
-        for_each_subsys(ss, i) {
-                if (!(opts.subsys_mask & (1 << i)) ||
-                    ss->root == &cgrp_dfl_root)
-                        continue;
-
-                if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
-                        mutex_unlock(&cgroup_mutex);
-                        msleep(10);
-                        ret = restart_syscall();
-                        goto out_free;
-                }
-                cgroup_put(&ss->root->cgrp);
-        }
-
-        for_each_root(root) {
-                bool name_match = false;
-
-                if (root == &cgrp_dfl_root)
-                        continue;
-
-                /*
-                 * If we asked for a name then it must match.  Also, if
-                 * name matches but sybsys_mask doesn't, we should fail.
-                 * Remember whether name matched.
-                 */
-                if (opts.name) {
-                        if (strcmp(opts.name, root->name))
-                                continue;
-                        name_match = true;
-                }
-
-                /*
-                 * If we asked for subsystems (or explicitly for no
-                 * subsystems) then they must match.
-                 */
-                if ((opts.subsys_mask || opts.none) &&
-                    (opts.subsys_mask != root->subsys_mask)) {
-                        if (!name_match)
-                                continue;
-                        ret = -EBUSY;
-                        goto out_unlock;
-                }
-
-                if (root->flags ^ opts.flags)
-                        pr_warn("new mount options do not match the existing superblock, will be ignored\n");
-
-                /*
-                 * We want to reuse @root whose lifetime is governed by its
-                 * ->cgrp.  Let's check whether @root is alive and keep it
-                 * that way.  As cgroup_kill_sb() can happen anytime, we
-                 * want to block it by pinning the sb so that @root doesn't
-                 * get killed before mount is complete.
-                 *
-                 * With the sb pinned, tryget_live can reliably indicate
-                 * whether @root can be reused.  If it's being killed,
-                 * drain it.  We can use wait_queue for the wait but this
-                 * path is super cold.  Let's just sleep a bit and retry.
-                 */
-                pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
-                if (IS_ERR(pinned_sb) ||
-                    !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
-                        mutex_unlock(&cgroup_mutex);
-                        if (!IS_ERR_OR_NULL(pinned_sb))
-                                deactivate_super(pinned_sb);
-                        msleep(10);
-                        ret = restart_syscall();
-                        goto out_free;
-                }
-
-                ret = 0;
-                goto out_unlock;
-        }
-
-        /*
-         * No such thing, create a new one.  name= matching without subsys
-         * specification is allowed for already existing hierarchies but we
-         * can't create new one without subsys specification.
-         */
-        if (!opts.subsys_mask && !opts.none) {
-                ret = -EINVAL;
-                goto out_unlock;
-        }
-
-        /* Hierarchies may only be created in the initial cgroup namespace. */
-        if (ns != &init_cgroup_ns) {
-                ret = -EPERM;
-                goto out_unlock;
-        }
-
-        root = kzalloc(sizeof(*root), GFP_KERNEL);
-        if (!root) {
-                ret = -ENOMEM;
-                goto out_unlock;
-        }
-
-        init_cgroup_root(root, &opts);
-
-        ret = cgroup_setup_root(root, opts.subsys_mask);
-        if (ret)
-                cgroup_free_root(root);
-
-out_unlock:
-        mutex_unlock(&cgroup_mutex);
-out_free:
-        kfree(opts.release_agent);
-        kfree(opts.name);
-
-        if (ret)
-                return ERR_PTR(ret);
-
-        dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
-                                 CGROUP_SUPER_MAGIC, ns);
-
-        /*
-         * If @pinned_sb, we're reusing an existing root and holding an
-         * extra ref on its sb.  Mount is complete.  Put the extra ref.
-         */
-        if (pinned_sb)
-                deactivate_super(pinned_sb);
-
-        return dentry;
-}
-
 static struct dentry *cgroup_mount(struct file_system_type *fs_type,
                          int flags, const char *unused_dev_name,
                          void *data)
@@ -4587,8 +4207,7 @@ out_destroy:
         return ERR_PTR(ret);
 }
 
-static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
-                        umode_t mode)
+int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
 {
         struct cgroup *parent, *cgrp;
         struct kernfs_node *kn;
@@ -4800,7 +4419,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
         return 0;
 };
 
-static int cgroup_rmdir(struct kernfs_node *kn)
+int cgroup_rmdir(struct kernfs_node *kn)
 {
         struct cgroup *cgrp;
         int ret = 0;
@@ -4818,15 +4437,6 @@ static int cgroup_rmdir(struct kernfs_node *kn)
         return ret;
 }
 
-static struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
-        .remount_fs             = cgroup1_remount,
-        .show_options           = cgroup1_show_options,
-        .rename                 = cgroup1_rename,
-        .mkdir                  = cgroup_mkdir,
-        .rmdir                  = cgroup_rmdir,
-        .show_path              = cgroup_show_path,
-};
-
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
         .remount_fs             = cgroup_remount,
         .mkdir                  = cgroup_mkdir,