RE: [PATCH 01/10] fs: don't allow kernel reads and writes without iter ops

David Laight
2020-08-27T15:58:08Z

From: Christoph Hellwig
> Sent: 27 August 2020 16:00
>
> Don't allow calling ->read or ->write with set_fs as a preparation for
> killing off set_fs. All the instances that we use kernel_read/write on
> are using the iter ops already.
>
> If a file has both the regular ->read/->write methods and the iter
> variants those could have different semantics for messed up enough
> drivers. Also fails the kernel access to them in that case.

Is there a real justification for that?
For system calls supplying both methods makes sense to avoid
the extra code paths for a simple read/write.

Any one stupid enough to make them behave differently gets
what they deserve.

David

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