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Message-ID: <dfebd3d3-29e6-b01e-a163-2ea0766062ae@bytedance.com>
Date:   Thu, 15 Sep 2022 15:43:48 +0800
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Subject: Re: [External] Re: [PATCH V3 3/6] erofs: introduce 'domain_id' mount
 option
To:     JeffleXu <jefflexu@linux.alibaba.com>,
        linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        yinxin.x@bytedance.com, huyue2@coolpad.com
References: <20220914105041.42970-1-zhujia.zj@bytedance.com>
 <20220914105041.42970-4-zhujia.zj@bytedance.com>
 <6644b9eb-d477-bbca-bbbe-b41776e38a46@linux.alibaba.com>
From:   Jia Zhu <zhujia.zj@bytedance.com>
In-Reply-To: <6644b9eb-d477-bbca-bbbe-b41776e38a46@linux.alibaba.com>
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在 2022/9/15 15:30, JeffleXu 写道:
> 
> 
> On 9/14/22 6:50 PM, Jia Zhu wrote:
>> Introduce 'domain_id' mount option to enable shared domain sementics.
>> In which case, the related cookie is shared if two mountpoints in the
>> same domain have the same data blob. Users could specify the name of
>> domain by this mount option.
>>
>> Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
> 
> Could you please move this patch to the end of this patch set, so that
> once the "domain_id" mount option is visible to users, this feature
> really works?
> 
Thanks for your example. I'll revise it.
> 
>> ---
>>   fs/erofs/internal.h |  1 +
>>   fs/erofs/super.c    | 17 +++++++++++++++++
>>   fs/erofs/sysfs.c    | 19 +++++++++++++++++--
>>   3 files changed, 35 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>> index aa71eb65e965..2d129c6b3027 100644
>> --- a/fs/erofs/internal.h
>> +++ b/fs/erofs/internal.h
>> @@ -76,6 +76,7 @@ struct erofs_mount_opts {
>>   #endif
>>   	unsigned int mount_opt;
>>   	char *fsid;
>> +	char *domain_id;
>>   };
> 
> Indeed we can add @domain_id field into struct erofs_mount_opts in prep
> for the following implementation of the domain_id feature. IOW, the
> above change can be folded into patch 4, just like what [1] does.
> 
> [1]
> https://github.com/torvalds/linux/commit/c6be2bd0a5dd91f98d6b5d2df2c79bc32993352c#diff-eee5fb30f4e83505af808386e84c953266d2fd2e76b6e66cb94cf6e849881240R77
> 
> 
>>   
>>   struct erofs_dev_context {
>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
>> index 7aa57dcebf31..856758ee4869 100644
>> --- a/fs/erofs/super.c
>> +++ b/fs/erofs/super.c
>> @@ -440,6 +440,7 @@ enum {
>>   	Opt_dax_enum,
>>   	Opt_device,
>>   	Opt_fsid,
>> +	Opt_domain_id,
>>   	Opt_err
>>   };
>>   
>> @@ -465,6 +466,7 @@ static const struct fs_parameter_spec erofs_fs_parameters[] = {
>>   	fsparam_enum("dax",		Opt_dax_enum, erofs_dax_param_enums),
>>   	fsparam_string("device",	Opt_device),
>>   	fsparam_string("fsid",		Opt_fsid),
>> +	fsparam_string("domain_id",	Opt_domain_id),
>>   	{}
>>   };
>>   
>> @@ -568,6 +570,16 @@ static int erofs_fc_parse_param(struct fs_context *fc,
>>   			return -ENOMEM;
>>   #else
>>   		errorfc(fc, "fsid option not supported");
>> +#endif
>> +		break;
>> +	case Opt_domain_id:
>> +#ifdef CONFIG_EROFS_FS_ONDEMAND
>> +		kfree(ctx->opt.domain_id);
>> +		ctx->opt.domain_id = kstrdup(param->string, GFP_KERNEL);
>> +		if (!ctx->opt.domain_id)
>> +			return -ENOMEM;
>> +#else
>> +		errorfc(fc, "domain_id option not supported");
>>   #endif
>>   		break;
>>   	default:
>> @@ -695,6 +707,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>>   	sb->s_fs_info = sbi;
>>   	sbi->opt = ctx->opt;
>>   	ctx->opt.fsid = NULL;
>> +	ctx->opt.domain_id = NULL;
>>   	sbi->devs = ctx->devs;
>>   	ctx->devs = NULL;
>>   
>> @@ -834,6 +847,7 @@ static void erofs_fc_free(struct fs_context *fc)
>>   
>>   	erofs_free_dev_context(ctx->devs);
>>   	kfree(ctx->opt.fsid);
>> +	kfree(ctx->opt.domain_id);
>>   	kfree(ctx);
>>   }
>>   
>> @@ -887,6 +901,7 @@ static void erofs_kill_sb(struct super_block *sb)
>>   	fs_put_dax(sbi->dax_dev, NULL);
>>   	erofs_fscache_unregister_fs(sb);
>>   	kfree(sbi->opt.fsid);
>> +	kfree(sbi->opt.domain_id);
>>   	kfree(sbi);
>>   	sb->s_fs_info = NULL;
>>   }
>> @@ -1040,6 +1055,8 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
>>   #ifdef CONFIG_EROFS_FS_ONDEMAND
>>   	if (opt->fsid)
>>   		seq_printf(seq, ",fsid=%s", opt->fsid);
>> +	if (opt->domain_id)
>> +		seq_printf(seq, ",domain_id=%s", opt->domain_id);
>>   #endif
>>   	return 0;
>>   }
>> diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
>> index c1383e508bbe..341fb43ad587 100644
>> --- a/fs/erofs/sysfs.c
>> +++ b/fs/erofs/sysfs.c
>> @@ -201,12 +201,27 @@ static struct kobject erofs_feat = {
>>   int erofs_register_sysfs(struct super_block *sb)
>>   {
>>   	struct erofs_sb_info *sbi = EROFS_SB(sb);
>> +	char *name;
>> +	char *str = NULL;
>>   	int err;
>>   
>> +	if (erofs_is_fscache_mode(sb)) {
>> +		if (sbi->opt.domain_id) {
>> +			str = kasprintf(GFP_KERNEL, "%s,%s", sbi->opt.domain_id,
>> +					sbi->opt.fsid);
>> +			if (!str)
>> +				return -ENOMEM;
>> +			name = str;
>> +		} else {
>> +			name = sbi->opt.fsid;
>> +		}
>> +	} else {
>> +		name = sb->s_id;
>> +	}
>>   	sbi->s_kobj.kset = &erofs_root;
>>   	init_completion(&sbi->s_kobj_unregister);
>> -	err = kobject_init_and_add(&sbi->s_kobj, &erofs_sb_ktype, NULL, "%s",
>> -			erofs_is_fscache_mode(sb) ? sbi->opt.fsid : sb->s_id);
>> +	err = kobject_init_and_add(&sbi->s_kobj, &erofs_sb_ktype, NULL, "%s", name);
>> +	kfree(str);
>>   	if (err)
>>   		goto put_sb_kobj;
>>   	return 0;
>