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Subject: Re: [RFC PATCH 4/5] ubifs: Introduce ACLs mount options
To: Li Zetao <lizetao1@huawei.com>, <richard@nod.at>
CC: <linux-kernel@vger.kernel.org>, <linux-mtd@lists.infradead.org>
References: <20240319161646.2153867-1-lizetao1@huawei.com>
 <20240319161646.2153867-5-lizetao1@huawei.com>
From: Zhihao Cheng <chengzhihao1@huawei.com>
Message-ID: <c3d5f06e-bdc4-4312-19a1-17a7a64e8795@huawei.com>
Date: Thu, 21 Mar 2024 14:49:04 +0800
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?? 2024/3/20 0:16, Li Zetao д??:
> Implement the ability to enable or disable the ACLs feature through
> mount options. "-o acl" option means enable and "-o noacl" means disable
> and it is enable by default.
> 
> Signed-off-by: Li Zetao <lizetao1@huawei.com>
> ---
>   fs/ubifs/super.c | 40 ++++++++++++++++++++++++++++++++++++++++
>   fs/ubifs/ubifs.h |  2 ++
>   2 files changed, 42 insertions(+)
> 
> diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
> index 7f4031a15f4d..ed03bf11e51d 100644
> --- a/fs/ubifs/super.c
> +++ b/fs/ubifs/super.c
> @@ -457,6 +457,13 @@ static int ubifs_show_options(struct seq_file *s, struct dentry *root)
>   	seq_printf(s, ",assert=%s", ubifs_assert_action_name(c));
>   	seq_printf(s, ",ubi=%d,vol=%d", c->vi.ubi_num, c->vi.vol_id);
>   
> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL

This config is introduced in pacth 5, we cannot use it in patch 4.
> +	if (c->mount_opts.acl == 2)
> +		seq_puts(s, ",acl");
> +	else if (c->mount_opts.acl == 1)
> +		seq_puts(s, ",noacl");
> +#endif
> +
>   	return 0;
>   }
>   
> @@ -967,6 +974,8 @@ static int check_volume_empty(struct ubifs_info *c)
>    * Opt_assert: set ubifs_assert() action
>    * Opt_auth_key: The key name used for authentication
>    * Opt_auth_hash_name: The hash type used for authentication
> + * Opt_acl: enable posix acl
> + * Opt_noacl: disable posix acl
>    * Opt_err: just end of array marker
>    */
>   enum {
> @@ -981,6 +990,8 @@ enum {
>   	Opt_auth_key,
>   	Opt_auth_hash_name,
>   	Opt_ignore,
> +	Opt_acl,
> +	Opt_noacl,
It would be better to update Documentation/filesystems/ubifs.rst to 
describe new mount options
>   	Opt_err,
>   };
>   
> @@ -997,6 +1008,8 @@ static const match_table_t tokens = {
>   	{Opt_ignore, "ubi=%s"},
>   	{Opt_ignore, "vol=%s"},
>   	{Opt_assert, "assert=%s"},
> +	{Opt_acl, "acl"},
> +	{Opt_noacl, "noacl"},
>   	{Opt_err, NULL},
>   };
>   
> @@ -1137,6 +1150,23 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
>   			break;
>   		case Opt_ignore:
>   			break;
> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
> +		case Opt_acl:
> +			c->mount_opts.acl = 2;
> +			c->vfs_sb->s_flags |= SB_POSIXACL;
> +			break;
> +		case Opt_noacl:
> +			c->mount_opts.acl = 1;
> +			c->vfs_sb->s_flags &= ~SB_POSIXACL;
> +			break;
> +#else
> +		case Opt_acl:
> +			ubifs_err(c, "acl options not supported");
> +			return -EINVAL;
> +		case Opt_noacl:
> +			ubifs_err(c, "noacl options not supported");
> +			return -EINVAL;
> +#endif
>   		default:
>   		{
>   			unsigned long flag;
> @@ -2011,12 +2041,17 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
>   	sync_filesystem(sb);
>   	dbg_gen("old flags %#lx, new flags %#x", sb->s_flags, *flags);
>   
> +	c->mount_opts.acl = 0;
>   	err = ubifs_parse_options(c, data, 1);

1. mount -onoacl /dev/ubi0_0 /mnt # After that, mount will show 'noacl' 
option
2. mount -oremount,xxx /dev/ubi0_0 /mnt
If 'xxx' has nothing to do with acl, c->mount_opts.acl is set as '0'. 
Then superblock flag is assigned with 'SB_POSIXACL' and mount will not 
display 'nocal'. Will it make user confused?
>   	if (err) {
>   		ubifs_err(c, "invalid or unknown remount parameter");
>   		return err;
>   	}
>   
> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
> +	if (!c->mount_opts.acl)
> +		c->vfs_sb->s_flags |= SB_POSIXACL;
> +#endif
>   	if (c->ro_mount && !(*flags & SB_RDONLY)) {
>   		if (c->ro_error) {
>   			ubifs_msg(c, "cannot re-mount R/W due to prior errors");
> @@ -2197,6 +2232,11 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
>   	if (err)
>   		goto out_close;
>   
> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
> +	if (!c->mount_opts.acl)
> +		c->vfs_sb->s_flags |= SB_POSIXACL;
> +#endif
> +
>   	/*
>   	 * UBIFS provides 'backing_dev_info' in order to disable read-ahead. For
>   	 * UBIFS, I/O is not deferred, it is done immediately in read_folio,
> diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
> index b0d3b076290d..4a6078cbb2f5 100644
> --- a/fs/ubifs/ubifs.h
> +++ b/fs/ubifs/ubifs.h
> @@ -956,6 +956,7 @@ struct ubifs_orphan {
>    *                  specified in @compr_type)
>    * @compr_type: compressor type to override the superblock compressor with
>    *              (%UBIFS_COMPR_NONE, etc)
> + * @acl: enable/disable posix acl (%0 default, %1 disable, %2 enable)
>    */
>   struct ubifs_mount_opts {
>   	unsigned int unmount_mode:2;
> @@ -963,6 +964,7 @@ struct ubifs_mount_opts {
>   	unsigned int chk_data_crc:2;
>   	unsigned int override_compr:1;
>   	unsigned int compr_type:2;
> +	unsigned int acl:2;
>   };
>   
>   /**
>