Yang, Am 27.09.2015 um 04:39 schrieb Dongsheng Yang: > We need to do nothing in ubifs, as all is already done in vfs. Please more details. :-) The current changelog reads like every filesystem should implement it as nop. Which is obviously not the case. fs/super.c checks whether ->freeze_fs() is implemented, so a nop-implementation does not make sense here. I bet you hit this in fs/ioctl.c: /* If filesystem doesn't support freeze feature, return. */ if (sb->s_op->freeze_fs == NULL && sb->s_op->freeze_super == NULL) return -EOPNOTSUPP; Correct? And the most important detail is missing, why is UBIFS allowed to have a nop-implementation? Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html