+ * layout information in the OST object EA:
+ * ldiskfs inode size: 160
+ * OST extended attributes size, including:
+ * ext4_xattr_header: 32
+ * LMA EA size: 24(lustre_mdt_attrs) +
+ * 16(xattr_entry) + 4("lma")
+ * FID EA size: 52(filter_fid) +
+ * 16(xattr_entry) + 4("fid")
+ * 160 + 32 + (24+20) + (52+20) = 308
+ */