[PATCH 9/9] mm: return an ERR_PTR from __filemap_get_folio

[Ryusuke Konishi]

On Wed, Jan 18, 2023 at 7:41 PM Christoph Hellwig wrote:
>
> Instead of returning NULL for all errors, distinguish between:
>
>  - no entry found and not asked to allocated (-ENOENT)
>  - failed to allocate memory (-ENOMEM)
>  - would block (-EAGAIN)
>
> so that callers don't have to guess the error based on the passed
> in flags.
>
> Also pass through the error through the direct callers:

> filemap_get_folio, filemap_lock_folio filemap_grab_folio
> and filemap_get_incore_folio.

As for the comments describing the return values of these callers,
isn't it necessary to rewrite the value from NULL in case of errors ?

Regards,
Ryusuke Konishi