inodes are actual objects in the kernel. Their inode number is supposed to be such that (device, inode, generation) uniquely identifies it, but the kernel itsel

inodes are actual objects in the kernel. Their inode number is supposed to be such that (device, inode, generation) uniquely identifies it, but the kernel itself doesn't really care about this (as long as your filesystem is not using the inode cache, which does use the inode number as a key). The way tmpfs works is that it uses the dirent cache as it's actual data structure (forcing the refcount of all cache entries >1 means they can't be evicted); those just directly contain pointers to inode objects. File data is stored in the page cache.