juicedata/juicefs · error

failed to chown object %s

Error message

failed to chown object %s

What it means

Returned by the 'change owner/group' funFS case when fi.Chown(key, "nobody", groupName) fails. This exercises filesystem-style ownership on file:// or jfs:// style backends; a failure means the underlying chown syscall/operation was refused — insufficient privileges, unsupported backend, or the user/group ('nobody'/groupName) does not exist. Note the format string uses %s with the error, printing the error text instead of a label.

Source

Thrown at cmd/objbench.go:1099

			}
			cnt, err := io.ReadAll(r)
			if err != nil {
				return fmt.Errorf("failed to get multipart upload file: %v", err)
			}
			if !bytes.Equal(cnt, bytes.Join(content, nil)) {
				return fmt.Errorf("the content of the multipart upload file is incorrect")
			}
			return nil
		}
		return utils.ErrNotSUP
	})

	funFSCase("change owner/group", func() error {
		if (strings.HasPrefix(blob.String(), "file://") || strings.HasPrefix(blob.String(), "jfs://")) && os.Getuid() != 0 {
			return errors.New("root required")
		}
		if err := fi.Chown(key, "nobody", groupName); err != nil {
			return fmt.Errorf("failed to chown object %s", err)
		}
		if objInfo, err := blob.Head(ctx, key); err != nil {
			return fmt.Errorf("failed to head object %s", err)
		} else if info, ok := objInfo.(object.File); ok {
			if info.Owner() != "nobody" {
				return fmt.Errorf("expect owner nobody but got %s", info.Owner())
			}
			if info.Group() != groupName {
				return fmt.Errorf("expect group %s but got %s", groupName, info.Group())
			}
		}
		return nil
	})

	funFSCase("change permission", func() error {
		if err := fi.Chmod(key, 0777); err != nil {
			return err
		}

View on GitHub (pinned to c9a67b23e8)

Solutions

1. Run objbench as root (or with CAP_CHOWN) when testing file:// or jfs:// backends.
2. Verify 'nobody' and the groupName exist on the system (id nobody; getent group <groupName>).
3. Confirm the backend FileSystem implements Chown; skip the case for backends lacking ownership support.
4. Fix the message to embed the underlying error with %w for diagnosis.

Example fix

// before
if err := fi.Chown(key, "nobody", groupName); err != nil {
	return fmt.Errorf("failed to chown object %s", err)
}
// after
if err := fi.Chown(key, "nobody", groupName); err != nil {
	return fmt.Errorf("failed to chown object: %w", err)
}

if (strings.HasPrefix(blob.String(), "file://") || strings.HasPrefix(blob.String(), "jfs://")) && os.Getuid() != 0 {
	return errors.New("root required")
}
if _, err := user.Lookup("nobody"); err != nil {
	return fmt.Errorf("user nobody missing: %w", err)
}
if _, err := user.LookupGroup(groupName); err != nil {
	return fmt.Errorf("group %s missing: %w", groupName, err)
}

if err := fi.Chown(key, "nobody", groupName); err != nil {
	return fmt.Errorf("failed to chown object: %w", err)
}

When it happens

Trigger: Running objbench FS cases as a non-root user on file:// or jfs:// (this is partially pre-checked), chown to 'nobody' or a nonexistent group, or a backend whose FileSystem implementation does not support Chown.

Common situations: Benchmark run without sudo against a local file system, container without CAP_CHOWN, groupName not defined on the host (/etc/group), or FUSE mount not allowing ownership changes by the mounting user.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

• get inode of %s: %s
• failed to get volume config %s: %v
• user(%s):group(%s) not found
• mkdir %s
• name is required

AI-assisted analysis of juicedata/juicefs@c9a67b23e8 (2026-09-06). Data as JSON: /api/errors/8c5c1fe2aa0c5b25. Report an issue: GitHub.