Re: [RFC] mm: optimise generic_file_read_iter

[Al Viro]

On Fri, Aug 06, 2021 at 12:42:43PM +0100, Pavel Begunkov wrote:
> Unless direct I/O path of generic_file_read_iter() ended up with an
> error or a short read, it doesn't use inode. So, load inode and size
> later, only when they're needed. This cuts two memory reads and also
> imrpoves code generation, e.g. loads from stack.

... and the same question here.

> NOTE: as a side effect, it reads inode->i_size after ->direct_IO(), and
> I'm not sure whether that's valid, so would be great to get feedback
> from someone who knows better.

Ought to be safe, I think, but again, how much effect have you observed
from the patch?