On Sun, Apr 1, 2018 at 7:57 AM, Chengguang Xu <cgxu519@xxxxxxx> wrote:
> Some overlayfs mount options cannot be changed via remount,
> but remount operation does not return proper error even if
> we specify different value to unchangeable options.
>
> This patch add option parsing support for remount so we can
> recogonize unchangeable options in remount.
>
> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx>
> ---
> fs/overlayfs/super.c | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 7c24619..5c8944b 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -446,14 +446,10 @@ static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
> return 0;
> }
>
> -static int ovl_parse_opt(char *opt, struct ovl_config *config)
> +static int ovl_parse_opt(char *opt, struct ovl_config *config, bool remount)
> {
> char *p;
>
> - config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
> - if (!config->redirect_mode)
> - return -ENOMEM;
> -
> while ((p = ovl_next_opt(&opt)) != NULL) {
> int token;
> substring_t args[MAX_OPT_ARGS];
> @@ -517,6 +513,9 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
> }
> }
>
> + if (remount)
> + return 0;
> +
> /* Workdir is useless in non-upper mount */
> if (!config->upperdir && config->workdir) {
> pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
> @@ -525,6 +524,13 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
> config->workdir = NULL;
> }
>
> + if (!config->redirect_mode) {
> + config->redirect_mode = kstrdup(ovl_redirect_mode_def(),
> + GFP_KERNEL);
> + if (!config->redirect_mode)
> + return -ENOMEM;
> + }
> +
You can move this chunk into ovl_parse_redirect_mode() no?
> return ovl_parse_redirect_mode(config, config->redirect_mode);
> }
>
> @@ -1250,6 +1256,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
> struct ovl_entry *oe;
> struct ovl_fs *ofs;
> struct cred *cred;
> + bool remount = false;
This helper var is not needed.
Thanks,
Amir.
> int err;
>
> err = -ENOMEM;
> @@ -1263,7 +1270,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
>
> ofs->config.index = ovl_index_def;
> ofs->config.nfs_export = ovl_nfs_export_def;
> - err = ovl_parse_opt((char *) data, &ofs->config);
> + err = ovl_parse_opt((char *) data, &ofs->config, remount);
> if (err)
> goto out_err;
>
> --
> 1.8.3.1
>
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