Miklos Szeredi [off-list ref] wrote:

The point is that generic operations already exist and no need to add
new, specialized ones to access metadata.

open and read already exist, yes, but the metadata isn't currently in
convenient inodes and dentries that you can just walk through.  So you're
going to end up with a specialised filesystem instead, I suspect.  Basically,
it's the same as your do-everything-through-/proc/self/fds/ approach.

And it's going to be heavier.  I don't know if you're planning on creating a
superblock each time you do an O_ALT open, but you will end up creating some
inodes, dentries and a file - even before you get to the reading bit.

David