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Message-ID: <b91ebdb0-bcca-18f9-6f0f-5eef6c72b42c@huawei.com>
Date: Fri, 22 Mar 2024 20:05:18 +0800
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Subject: Re: [RFC PATCH 4/5] ubifs: Introduce ACLs mount options
Content-Language: en-US
To: Zhihao Cheng <chengzhihao1@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>
 <c3d5f06e-bdc4-4312-19a1-17a7a64e8795@huawei.com>
From: Li Zetao <lizetao1@huawei.com>
In-Reply-To: <c3d5f06e-bdc4-4312-19a1-17a7a64e8795@huawei.com>
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Hi,

On 2024/3/21 14:49, Zhihao Cheng wrote:
> 在 2024/3/20 0:16, Li Zetao 写道:
>> 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
Ok.
>>       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?
I have tested this use case and it works fine. This is because the mount 
options will be re-parsed during remount, just like the last mount. But 
this is indeed redundant. I adjusted it to make it more reasonable.
>>       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;
>>   };
>>   /**
>>
>