linux-kernel - RE: [PATCH 2/2] exfat: allow to change some mount options for remount

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Date:   Mon, 15 Jun 2020 09:18:42 +0900
From:   "Namjae Jeon" <namjae.jeon@...sung.com>
To:     "'Hyunchul Lee'" <hyc.lee@...il.com>
Cc:     <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "'Sungjong Seo'" <sj1557.seo@...sung.com>
Subject: RE: [PATCH 2/2] exfat: allow to change some mount options for
 remount

> Allow to change permission masks, allow_utime, errors. But ignore other options.
> 
> Signed-off-by: Hyunchul Lee <hyc.lee@...il.com>
> ---
>  fs/exfat/super.c | 40 +++++++++++++++++++++++++++++-----------
>  1 file changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c index 61c6cf240c19..3c1d47289ba2 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -696,9 +696,13 @@ static void exfat_free(struct fs_context *fc)  static int
> exfat_reconfigure(struct fs_context *fc)  {
>  	struct super_block *sb = fc->root->d_sb;
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +	struct exfat_mount_options *new_opts;
>  	int ret;
>  	bool new_rdonly;
> 
> +	new_opts = &((struct exfat_sb_info *)fc->s_fs_info)->options;
> +
>  	new_rdonly = fc->sb_flags & SB_RDONLY;
>  	if (new_rdonly != sb_rdonly(sb)) {
>  		if (new_rdonly) {
> @@ -708,6 +712,12 @@ static int exfat_reconfigure(struct fs_context *fc)
>  				return ret;
>  		}
>  	}
> +
> +	/* allow to change these options but ignore others */
> +	sbi->options.fs_fmask = new_opts->fs_fmask;
> +	sbi->options.fs_dmask = new_opts->fs_dmask;
> +	sbi->options.allow_utime = new_opts->allow_utime;
> +	sbi->options.errors = new_opts->errors;
Is there any reason why you allow a few options on remount ?
>  	return 0;
>  }
> 
> @@ -726,17 +736,25 @@ static int exfat_init_fs_context(struct fs_context *fc)
>  	if (!sbi)
>  		return -ENOMEM;
> 
> -	mutex_init(&sbi->s_lock);
> -	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
> -			DEFAULT_RATELIMIT_BURST);
> -
> -	sbi->options.fs_uid = current_uid();
> -	sbi->options.fs_gid = current_gid();
> -	sbi->options.fs_fmask = current->fs->umask;
> -	sbi->options.fs_dmask = current->fs->umask;
> -	sbi->options.allow_utime = -1;
> -	sbi->options.iocharset = exfat_default_iocharset;
> -	sbi->options.errors = EXFAT_ERRORS_RO;
> +	if (fc->root) {
> +		/* reconfiguration */
> +		memcpy(&sbi->options, &EXFAT_SB(fc->root->d_sb)->options,
> +			sizeof(struct exfat_mount_options));
> +		sbi->options.iocharset = exfat_default_iocharset;
> +	} else {
> +		mutex_init(&sbi->s_lock);
> +		ratelimit_state_init(&sbi->ratelimit,
> +				DEFAULT_RATELIMIT_INTERVAL,
> +				DEFAULT_RATELIMIT_BURST);
> +
> +		sbi->options.fs_uid = current_uid();
> +		sbi->options.fs_gid = current_gid();
> +		sbi->options.fs_fmask = current->fs->umask;
> +		sbi->options.fs_dmask = current->fs->umask;
> +		sbi->options.allow_utime = -1;
> +		sbi->options.iocharset = exfat_default_iocharset;
> +		sbi->options.errors = EXFAT_ERRORS_RO;
> +	}
> 
>  	fc->s_fs_info = sbi;
>  	fc->ops = &exfat_context_ops;
> --
> 2.17.1