Re: [PATCH 3/5] befs: convert befs to use the new mount api

[Jan Kara <jack@suse.cz>]

On Mon 16-09-24 13:26:20, Eric Sandeen wrote:
> Convert the befs filesystem to use the new mount API.
> Tested by comparing random mount & remount options before and after
> the change.
> 
> Cc: Luis de Bethencourt <luisbg@kernel.org>
> Cc: Salah Triki <salah.triki@gmail.com>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/befs/linuxvfs.c | 199 +++++++++++++++++++++++----------------------
>  1 file changed, 102 insertions(+), 97 deletions(-)
> 
> diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c
> index f92f108840f5..8f430ff8e445 100644
> --- a/fs/befs/linuxvfs.c
> +++ b/fs/befs/linuxvfs.c
> @@ -11,12 +11,13 @@
>  #include <linux/module.h>
>  #include <linux/slab.h>
>  #include <linux/fs.h>
> +#include <linux/fs_context.h>
> +#include <linux/fs_parser.h>
>  #include <linux/errno.h>
>  #include <linux/stat.h>
>  #include <linux/nls.h>
>  #include <linux/buffer_head.h>
>  #include <linux/vfs.h>
> -#include <linux/parser.h>
>  #include <linux/namei.h>
>  #include <linux/sched.h>
>  #include <linux/cred.h>
> @@ -54,22 +55,20 @@ static int befs_utf2nls(struct super_block *sb, const char *in, int in_len,
>  static int befs_nls2utf(struct super_block *sb, const char *in, int in_len,
>  			char **out, int *out_len);
>  static void befs_put_super(struct super_block *);
> -static int befs_remount(struct super_block *, int *, char *);
>  static int befs_statfs(struct dentry *, struct kstatfs *);
>  static int befs_show_options(struct seq_file *, struct dentry *);
> -static int parse_options(char *, struct befs_mount_options *);
>  static struct dentry *befs_fh_to_dentry(struct super_block *sb,
>  				struct fid *fid, int fh_len, int fh_type);
>  static struct dentry *befs_fh_to_parent(struct super_block *sb,
>  				struct fid *fid, int fh_len, int fh_type);
>  static struct dentry *befs_get_parent(struct dentry *child);
> +static void befs_free_fc(struct fs_context *fc);
>  
>  static const struct super_operations befs_sops = {
>  	.alloc_inode	= befs_alloc_inode,	/* allocate a new inode */
>  	.free_inode	= befs_free_inode, /* deallocate an inode */
>  	.put_super	= befs_put_super,	/* uninit super */
>  	.statfs		= befs_statfs,	/* statfs */
> -	.remount_fs	= befs_remount,
>  	.show_options	= befs_show_options,
>  };
>  
> @@ -672,92 +671,53 @@ static struct dentry *befs_get_parent(struct dentry *child)
>  }
>  
>  enum {
> -	Opt_uid, Opt_gid, Opt_charset, Opt_debug, Opt_err,
> +	Opt_uid, Opt_gid, Opt_charset, Opt_debug,
>  };
>  
> -static const match_table_t befs_tokens = {
> -	{Opt_uid, "uid=%d"},
> -	{Opt_gid, "gid=%d"},
> -	{Opt_charset, "iocharset=%s"},
> -	{Opt_debug, "debug"},
> -	{Opt_err, NULL}
> +static const struct fs_parameter_spec befs_param_spec[] = {
> +	fsparam_uid	("uid",		Opt_uid),
> +	fsparam_gid	("gid",		Opt_gid),
> +	fsparam_string	("iocharset",	Opt_charset),
> +	fsparam_flag	("debug",	Opt_debug),
> +	{}
>  };
>  
>  static int
> -parse_options(char *options, struct befs_mount_options *opts)
> +befs_parse_param(struct fs_context *fc, struct fs_parameter *param)
>  {
> -	char *p;
> -	substring_t args[MAX_OPT_ARGS];
> -	int option;
> -	kuid_t uid;
> -	kgid_t gid;
> -
> -	/* Initialize options */
> -	opts->uid = GLOBAL_ROOT_UID;
> -	opts->gid = GLOBAL_ROOT_GID;
> -	opts->use_uid = 0;
> -	opts->use_gid = 0;
> -	opts->iocharset = NULL;
> -	opts->debug = 0;
> -
> -	if (!options)
> -		return 1;
> -
> -	while ((p = strsep(&options, ",")) != NULL) {
> -		int token;
> -
> -		if (!*p)
> -			continue;
> -
> -		token = match_token(p, befs_tokens, args);
> -		switch (token) {
> -		case Opt_uid:
> -			if (match_int(&args[0], &option))
> -				return 0;
> -			uid = INVALID_UID;
> -			if (option >= 0)
> -				uid = make_kuid(current_user_ns(), option);
> -			if (!uid_valid(uid)) {
> -				pr_err("Invalid uid %d, "
> -				       "using default\n", option);
> -				break;
> -			}
> -			opts->uid = uid;
> -			opts->use_uid = 1;
> -			break;
> -		case Opt_gid:
> -			if (match_int(&args[0], &option))
> -				return 0;
> -			gid = INVALID_GID;
> -			if (option >= 0)
> -				gid = make_kgid(current_user_ns(), option);
> -			if (!gid_valid(gid)) {
> -				pr_err("Invalid gid %d, "
> -				       "using default\n", option);
> -				break;
> -			}
> -			opts->gid = gid;
> -			opts->use_gid = 1;
> -			break;
> -		case Opt_charset:
> -			kfree(opts->iocharset);
> -			opts->iocharset = match_strdup(&args[0]);
> -			if (!opts->iocharset) {
> -				pr_err("allocation failure for "
> -				       "iocharset string\n");
> -				return 0;
> -			}
> -			break;
> -		case Opt_debug:
> -			opts->debug = 1;
> -			break;
> -		default:
> -			pr_err("Unrecognized mount option \"%s\" "
> -			       "or missing value\n", p);
> -			return 0;
> -		}
> +	struct befs_mount_options *opts = fc->fs_private;
> +	int token;
> +	struct fs_parse_result result;
> +
> +	/* befs ignores all options on remount */
> +	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE)
> +		return 0;
> +
> +	token = fs_parse(fc, befs_param_spec, param, &result);
> +	if (token < 0)
> +		return token;
> +
> +	switch (token) {
> +	case Opt_uid:
> +		opts->uid = result.uid;
> +		opts->use_uid = 1;
> +		break;
> +	case Opt_gid:
> +		opts->gid = result.gid;
> +		opts->use_gid = 1;
> +		break;
> +	case Opt_charset:
> +		kfree(opts->iocharset);
> +		opts->iocharset = param->string;
> +		param->string = NULL;
> +		break;
> +	case Opt_debug:
> +		opts->debug = 1;
> +		break;
> +	default:
> +		return -EINVAL;
>  	}
> -	return 1;
> +	return 0;
>  }
>  
>  static int befs_show_options(struct seq_file *m, struct dentry *root)
> @@ -793,6 +753,21 @@ befs_put_super(struct super_block *sb)
>  	sb->s_fs_info = NULL;
>  }
>  
> +/*
> + * Copy the parsed options into the sbi mount_options member
> + */
> +static void
> +befs_set_options(struct befs_sb_info *sbi, struct befs_mount_options *opts)
> +{
> +	sbi->mount_opts.uid = opts->uid;
> +	sbi->mount_opts.gid = opts->gid;
> +	sbi->mount_opts.use_uid = opts->use_uid;
> +	sbi->mount_opts.use_gid = opts->use_gid;
> +	sbi->mount_opts.debug = opts->debug;
> +	sbi->mount_opts.iocharset = opts->iocharset;
> +	opts->iocharset = NULL;
> +}
> +
>  /* Allocate private field of the superblock, fill it.
>   *
>   * Finish filling the public superblock fields
> @@ -800,7 +775,7 @@ befs_put_super(struct super_block *sb)
>   * Load a set of NLS translations if needed.
>   */
>  static int
> -befs_fill_super(struct super_block *sb, void *data, int silent)
> +befs_fill_super(struct super_block *sb, struct fs_context *fc)
>  {
>  	struct buffer_head *bh;
>  	struct befs_sb_info *befs_sb;
> @@ -810,6 +785,8 @@ befs_fill_super(struct super_block *sb, void *data, int silent)
>  	const unsigned long sb_block = 0;
>  	const off_t x86_sb_off = 512;
>  	int blocksize;
> +	struct befs_mount_options *parsed_opts = fc->fs_private;
> +	int silent = fc->sb_flags & SB_SILENT;
>  
>  	sb->s_fs_info = kzalloc(sizeof(*befs_sb), GFP_KERNEL);
>  	if (sb->s_fs_info == NULL)
> @@ -817,11 +794,7 @@ befs_fill_super(struct super_block *sb, void *data, int silent)
>  
>  	befs_sb = BEFS_SB(sb);
>  
> -	if (!parse_options((char *) data, &befs_sb->mount_opts)) {
> -		if (!silent)
> -			befs_error(sb, "cannot parse mount options");
> -		goto unacquire_priv_sbp;
> -	}
> +	befs_set_options(befs_sb, parsed_opts);
>  
>  	befs_debug(sb, "---> %s", __func__);
>  
> @@ -934,10 +907,10 @@ befs_fill_super(struct super_block *sb, void *data, int silent)
>  }
>  
>  static int
> -befs_remount(struct super_block *sb, int *flags, char *data)
> +befs_reconfigure(struct fs_context *fc)
>  {
> -	sync_filesystem(sb);
> -	if (!(*flags & SB_RDONLY))
> +	sync_filesystem(fc->root->d_sb);
> +	if (!(fc->sb_flags & SB_RDONLY))
>  		return -EINVAL;
>  	return 0;
>  }
> @@ -965,19 +938,51 @@ befs_statfs(struct dentry *dentry, struct kstatfs *buf)
>  	return 0;
>  }
>  
> -static struct dentry *
> -befs_mount(struct file_system_type *fs_type, int flags, const char *dev_name,
> -	    void *data)
> +static int befs_get_tree(struct fs_context *fc)
> +{
> +	return get_tree_bdev(fc, befs_fill_super);
> +}
> +
> +static const struct fs_context_operations befs_context_ops = {
> +	.parse_param	= befs_parse_param,
> +	.get_tree	= befs_get_tree,
> +	.reconfigure	= befs_reconfigure,
> +	.free		= befs_free_fc,
> +};
> +
> +static int befs_init_fs_context(struct fs_context *fc)
> +{
> +	struct befs_mount_options *opts;
> +
> +	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
> +	if (!opts)
> +		return -ENOMEM;
> +
> +	/* Initialize options */
> +	opts->uid = GLOBAL_ROOT_UID;
> +	opts->gid = GLOBAL_ROOT_GID;
> +
> +	fc->fs_private = opts;
> +	fc->ops = &befs_context_ops;
> +
> +	return 0;
> +}
> +
> +static void befs_free_fc(struct fs_context *fc)
>  {
> -	return mount_bdev(fs_type, flags, dev_name, data, befs_fill_super);
> +	struct befs_mount_options *opts = fc->fs_private;
> +
> +	kfree(opts->iocharset);
> +	kfree(fc->fs_private);
>  }
>  
>  static struct file_system_type befs_fs_type = {
>  	.owner		= THIS_MODULE,
>  	.name		= "befs",
> -	.mount		= befs_mount,
>  	.kill_sb	= kill_block_super,
>  	.fs_flags	= FS_REQUIRES_DEV,
> +	.init_fs_context = befs_init_fs_context,
> +	.parameters	= befs_param_spec,
>  };
>  MODULE_ALIAS_FS("befs");
>  
> -- 
> 2.46.0
> 
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR