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

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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@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;




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