cgroup: separate out cgroup1_kf_syscall_ops

Currently, cgroup_kf_syscall_ops is shared by v1 and v2 and the
specific methods test the version and take different actions.  Split
out v1 functions and put them in cgroup1_kf_syscall_ops and remove the
now unnecessary explicit branches in specific methods.

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

3 files changed, 30 insertions, 25 deletions

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index dca3193bd9d2..5790e5ff9a0f 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -95,8 +95,8 @@ extern const struct file_operations proc_cgroupstats_operations;
 
 bool cgroup_ssid_no_v1(int ssid);
 void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
-int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-                  const char *new_name_str);
+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);
 
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 7af745a46f91..0b2c24f0b310 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -800,8 +800,8 @@ out_free:
 /*
  * cgroup_rename - Only allow simple rename of directories in place.
  */
-int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
-                  const char *new_name_str)
+int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+                   const char *new_name_str)
 {
         struct cgroup *cgrp = kn->priv;
         int ret;
@@ -812,13 +812,6 @@ int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
                 return -EIO;
 
         /*
-         * This isn't a proper migration and its usefulness is very
-         * limited.  Disallow on the default hierarchy.
-         */
-        if (cgroup_on_dfl(cgrp))
-                return -EPERM;
-
-        /*
          * We're gonna grab cgroup_mutex which nests outside kernfs
          * active_ref.  kernfs_rename() doesn't require active_ref
          * protection.  Break them before grabbing cgroup_mutex.
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 228dd9ae708b..de6a2ac41d0b 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1232,6 +1232,7 @@ 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,
@@ -1566,16 +1567,15 @@ static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
         return len;
 }
 
-static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
+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;
 
-        if (root != &cgrp_dfl_root)
-                for_each_subsys(ss, ssid)
-                        if (root->subsys_mask & (1 << ssid))
-                                seq_show_option(seq, ss->legacy_name, NULL);
+        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)
@@ -1736,18 +1736,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
         return 0;
 }
 
-static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
+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;
 
-        if (root == &cgrp_dfl_root) {
-                pr_err("remount is not allowed\n");
-                return -EINVAL;
-        }
-
         cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
 
         /* See what subsystems are wanted */
@@ -1798,6 +1793,12 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
         return ret;
 }
 
+static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
+{
+        pr_err("remount is not allowed\n");
+        return -EINVAL;
+}
+
 /*
  * To reduce the fork() overhead for systems that are not actually using
  * their cgroups capability, we don't maintain the lists running through
@@ -1900,6 +1901,7 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 {
         LIST_HEAD(tmp_links);
         struct cgroup *root_cgrp = &root->cgrp;
+        struct kernfs_syscall_ops *kf_sops;
         struct css_set *cset;
         int i, ret;
 
@@ -1931,7 +1933,10 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
         if (ret)
                 goto cancel_ref;
 
-        root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
+        kf_sops = root == &cgrp_dfl_root ?
+                &cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops;
+
+        root->kf_root = kernfs_create_root(kf_sops,
                                            KERNFS_ROOT_CREATE_DEACTIVATED,
                                            root_cgrp);
         if (IS_ERR(root->kf_root)) {
@@ -4813,12 +4818,19 @@ 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,
-        .show_options           = cgroup_show_options,
         .mkdir                  = cgroup_mkdir,
         .rmdir                  = cgroup_rmdir,
-        .rename                 = cgroup_rename,
         .show_path              = cgroup_show_path,
 };