This fixes getfattr(1) which otherwise fails with ERANGE.

This will catch potential data loss when the underlying storage is
full or faulty.

Writing the notification must be synchronized with closing the FUSE
connection.

6g has changed its baseaddress. Users that require small inode numbers
should just use portableHandleMap.

look like a race condition.

It had a race condition. Removing it frees us from having go-routines
hanging around after the FS is unmounted.