RE: [PATCH 1/2] fs/efivarfs: restrict inode permissions

[Luck, Tony]

> read() will make two calls - one to obtain the size of the variable, the
> other to read it. It looks like cat will also trigger an fstat(), so we're
> probably also making a call for that. There's presumably some optimisation
> that could be made there if we trust the firmware not to change the size
> behind our back.

Hmmm. "ls -l" reports the size of each of the files without causing any SMIs,
so Linux has that cached someplace and "read" is being silly making a call
to get something that we already know.  Unless we think the size may be
changing asynchronously and are OK with reporting a stale value for "stat"
but want the actual value for "read".

-Tony