#include <linux/module.h>
 #include <linux/fs.h>
-#include <linux/mount.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include <linux/pagemap.h>
 #include <linux/init.h>
 #include <linux/kobject.h>
 #include <linux/fsnotify.h>
 #include <linux/string.h>
 #include <linux/seq_file.h>
-#include <linux/parser.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
 #include <linux/security.h>
        return inode;
 }
 
-struct debugfs_mount_opts {
+struct debugfs_fs_info {
        kuid_t uid;
        kgid_t gid;
        umode_t mode;
        Opt_uid,
        Opt_gid,
        Opt_mode,
-       Opt_err
 };
 
-static const match_table_t tokens = {
-       {Opt_uid, "uid=%u"},
-       {Opt_gid, "gid=%u"},
-       {Opt_mode, "mode=%o"},
-       {Opt_err, NULL}
+static const struct fs_parameter_spec debugfs_param_specs[] = {
+       fsparam_u32     ("gid",         Opt_gid),
+       fsparam_u32oct  ("mode",        Opt_mode),
+       fsparam_u32     ("uid",         Opt_uid),
+       {}
 };
 
-struct debugfs_fs_info {
-       struct debugfs_mount_opts mount_opts;
-};
-
-static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
+static int debugfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 {
-       substring_t args[MAX_OPT_ARGS];
-       int option;
-       int token;
+       struct debugfs_fs_info *opts = fc->s_fs_info;
+       struct fs_parse_result result;
        kuid_t uid;
        kgid_t gid;
-       char *p;
-
-       opts->opts = 0;
-       opts->mode = DEBUGFS_DEFAULT_MODE;
-
-       while ((p = strsep(&data, ",")) != NULL) {
-               if (!*p)
-                       continue;
-
-               token = match_token(p, tokens, args);
-               switch (token) {
-               case Opt_uid:
-                       if (match_int(&args[0], &option))
-                               return -EINVAL;
-                       uid = make_kuid(current_user_ns(), option);
-                       if (!uid_valid(uid))
-                               return -EINVAL;
-                       opts->uid = uid;
-                       break;
-               case Opt_gid:
-                       if (match_int(&args[0], &option))
-                               return -EINVAL;
-                       gid = make_kgid(current_user_ns(), option);
-                       if (!gid_valid(gid))
-                               return -EINVAL;
-                       opts->gid = gid;
-                       break;
-               case Opt_mode:
-                       if (match_octal(&args[0], &option))
-                               return -EINVAL;
-                       opts->mode = option & S_IALLUGO;
-                       break;
-               /*
-                * We might like to report bad mount options here;
-                * but traditionally debugfs has ignored all mount options
-                */
-               }
-
-               opts->opts |= BIT(token);
+       int opt;
+
+       opt = fs_parse(fc, debugfs_param_specs, param, &result);
+       if (opt < 0)
+               return opt;
+
+       switch (opt) {
+       case Opt_uid:
+               uid = make_kuid(current_user_ns(), result.uint_32);
+               if (!uid_valid(uid))
+                       return invalf(fc, "Unknown uid");
+               opts->uid = uid;
+               break;
+       case Opt_gid:
+               gid = make_kgid(current_user_ns(), result.uint_32);
+               if (!gid_valid(gid))
+                       return invalf(fc, "Unknown gid");
+               opts->gid = gid;
+               break;
+       case Opt_mode:
+               opts->mode = result.uint_32 & S_IALLUGO;
+               break;
+       /*
+        * We might like to report bad mount options here;
+        * but traditionally debugfs has ignored all mount options
+        */
        }
 
+       opts->opts |= BIT(opt);
+
        return 0;
 }
 
 {
        struct debugfs_fs_info *fsi = sb->s_fs_info;
        struct inode *inode = d_inode(sb->s_root);
-       struct debugfs_mount_opts *opts = &fsi->mount_opts;
 
        /*
         * On remount, only reset mode/uid/gid if they were provided as mount
         * options.
         */
 
-       if (!remount || opts->opts & BIT(Opt_mode)) {
+       if (!remount || fsi->opts & BIT(Opt_mode)) {
                inode->i_mode &= ~S_IALLUGO;
-               inode->i_mode |= opts->mode;
+               inode->i_mode |= fsi->mode;
        }
 
-       if (!remount || opts->opts & BIT(Opt_uid))
-               inode->i_uid = opts->uid;
+       if (!remount || fsi->opts & BIT(Opt_uid))
+               inode->i_uid = fsi->uid;
 
-       if (!remount || opts->opts & BIT(Opt_gid))
-               inode->i_gid = opts->gid;
+       if (!remount || fsi->opts & BIT(Opt_gid))
+               inode->i_gid = fsi->gid;
 }
 
 static void debugfs_apply_options(struct super_block *sb)
        _debugfs_apply_options(sb, true);
 }
 
-static int debugfs_remount(struct super_block *sb, int *flags, char *data)
+static int debugfs_reconfigure(struct fs_context *fc)
 {
-       int err;
-       struct debugfs_fs_info *fsi = sb->s_fs_info;
+       struct super_block *sb = fc->root->d_sb;
+       struct debugfs_fs_info *sb_opts = sb->s_fs_info;
+       struct debugfs_fs_info *new_opts = fc->s_fs_info;
 
        sync_filesystem(sb);
-       err = debugfs_parse_options(data, &fsi->mount_opts);
-       if (err)
-               goto fail;
 
+       /* structure copy of new mount options to sb */
+       *sb_opts = *new_opts;
        debugfs_apply_options_remount(sb);
 
-fail:
-       return err;
+       return 0;
 }
 
 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
 {
        struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
-       struct debugfs_mount_opts *opts = &fsi->mount_opts;
 
-       if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
+       if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID))
                seq_printf(m, ",uid=%u",
-                          from_kuid_munged(&init_user_ns, opts->uid));
-       if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
+                          from_kuid_munged(&init_user_ns, fsi->uid));
+       if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID))
                seq_printf(m, ",gid=%u",
-                          from_kgid_munged(&init_user_ns, opts->gid));
-       if (opts->mode != DEBUGFS_DEFAULT_MODE)
-               seq_printf(m, ",mode=%o", opts->mode);
+                          from_kgid_munged(&init_user_ns, fsi->gid));
+       if (fsi->mode != DEBUGFS_DEFAULT_MODE)
+               seq_printf(m, ",mode=%o", fsi->mode);
 
        return 0;
 }
 
 static const struct super_operations debugfs_super_operations = {
        .statfs         = simple_statfs,
-       .remount_fs     = debugfs_remount,
        .show_options   = debugfs_show_options,
        .free_inode     = debugfs_free_inode,
 };
        .d_automount = debugfs_automount,
 };
 
-static int debug_fill_super(struct super_block *sb, void *data, int silent)
+static int debugfs_fill_super(struct super_block *sb, struct fs_context *fc)
 {
        static const struct tree_descr debug_files[] = {{""}};
-       struct debugfs_fs_info *fsi;
        int err;
 
-       fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
-       sb->s_fs_info = fsi;
-       if (!fsi) {
-               err = -ENOMEM;
-               goto fail;
-       }
-
-       err = debugfs_parse_options(data, &fsi->mount_opts);
+       err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
        if (err)
-               goto fail;
-
-       err  =  simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
-       if (err)
-               goto fail;
+               return err;
 
        sb->s_op = &debugfs_super_operations;
        sb->s_d_op = &debugfs_dops;
        debugfs_apply_options(sb);
 
        return 0;
-
-fail:
-       kfree(fsi);
-       sb->s_fs_info = NULL;
-       return err;
 }
 
-static struct dentry *debug_mount(struct file_system_type *fs_type,
-                       int flags, const char *dev_name,
-                       void *data)
+static int debugfs_get_tree(struct fs_context *fc)
 {
        if (!(debugfs_allow & DEBUGFS_ALLOW_API))
-               return ERR_PTR(-EPERM);
+               return -EPERM;
+
+       return get_tree_single(fc, debugfs_fill_super);
+}
+
+static void debugfs_free_fc(struct fs_context *fc)
+{
+       kfree(fc->s_fs_info);
+}
 
-       return mount_single(fs_type, flags, data, debug_fill_super);
+static const struct fs_context_operations debugfs_context_ops = {
+       .free           = debugfs_free_fc,
+       .parse_param    = debugfs_parse_param,
+       .get_tree       = debugfs_get_tree,
+       .reconfigure    = debugfs_reconfigure,
+};
+
+static int debugfs_init_fs_context(struct fs_context *fc)
+{
+       struct debugfs_fs_info *fsi;
+
+       fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
+       if (!fsi)
+               return -ENOMEM;
+
+       fsi->mode = DEBUGFS_DEFAULT_MODE;
+
+       fc->s_fs_info = fsi;
+       fc->ops = &debugfs_context_ops;
+       return 0;
 }
 
 static struct file_system_type debug_fs_type = {
        .owner =        THIS_MODULE,
        .name =         "debugfs",
-       .mount =        debug_mount,
+       .init_fs_context = debugfs_init_fs_context,
+       .parameters =   debugfs_param_specs,
        .kill_sb =      kill_litter_super,
 };
 MODULE_ALIAS_FS("debugfs");