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

Jia Zhu <zhujia.zj@xxxxxxxxxxxxx> · Thu, 1 Sep 2022 11:45:01 +0800

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






