Re: [External] Re: [PATCH V3 3/6] erofs: introduce 'domain_id' mount option

[Jia Zhu <zhujia.zj@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
>
> 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;