On Sun, May 21, 2017 at 10:20:49PM +0200, Richard Weinberger wrote: > The new feature UBIFS_FLG_PARENTPOINTER allows looking > up the parent. Usually the Linux VFS walks down the filesystem > and no parent pointers are needed. But when a filesystem > is exportable via NFS such a lookup is needed. > We can use a padding field in struct ubifs_ino_node to > maintain a pointer to the parent inode. Note that nfsd/exportfs will only do this for directories, and beacause we hardlinks for other objects that is an important distinction. I think the ubifs code should make sure to only maintain the parent pointers for directories, otherwise confusion and abuses will happen.