Re: [External] Re: [RFC PATCH 1/5] erofs: add 'domain_id' mount option for on-demand read sementics

[Jia Zhu]

在 2022/9/1 11:31, Gao Xiang 写道:
> On Wed, Aug 31, 2022 at 08:31:21PM +0800, 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>
> > ---
> >   fs/erofs/internal.h |  1 +
> >   fs/erofs/super.c    | 17 +++++++++++++++++
> >   2 files changed, 18 insertions(+)
> >
> > diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> > index cfee49d33b95..fe435d077f1a 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;
> >   };
> >   
> >   struct erofs_dev_context {
> > diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> > index 3173debeaa5a..fb5a84a07bd5 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:
> > +		kfree(ctx->opt.domain_id);
> > +		ctx->opt.domain_id = kstrdup(param->string, GFP_KERNEL);
> > +		if (!ctx->opt.domain_id)
> > +			return -ENOMEM;
> > +#ifdef CONFIG_EROFS_FS_ONDEMAND
> > +#else
> > +		errorfc(fc, "domain_id option not supported");
>
> Just one question, why not write as below?
>
> #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
>
> Thanks,
> Gao Xiang
Thanks for catching this. Maybe something went wrong when I split the
patch. I'll fix it in next version.

Thanks,
Zhu Jia
> >   #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;
> >   
> > @@ -838,6 +851,7 @@ 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);
> >   }
> >   
> > @@ -892,6 +906,7 @@ static void erofs_kill_sb(struct super_block *sb)
> >   	erofs_fscache_unregister_cookie(&sbi->s_fscache);
> >   	erofs_fscache_unregister_fs(sb);
> >   	kfree(sbi->opt.fsid);
> > +	kfree(sbi->opt.domain_id);
> >   	kfree(sbi);
> >   	sb->s_fs_info = NULL;
> >   }
> > @@ -1044,6 +1059,8 @@ 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;
> >   }
> > --
> > 2.20.1