Re: [PATCH v2 05/16] iomap: propagate iomap_read_folio() error to caller

Joanne Koong
2025-09-12T16:28:14Z

On Thu, Sep 11, 2025 at 7:13 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Mon, Sep 08, 2025 at 11:51:11AM -0700, Joanne Koong wrote:
> > Propagate any error encountered in iomap_read_folio() back up to its
> > caller (otherwise a default -EIO will be passed up by
> > filemap_read_folio() to callers). This is standard behavior for how
> > other filesystems handle their ->read_folio() errors as well.
> >
> > Remove the out of date comment about setting the folio error flag.
> > Folio error flags were removed in commit 1f56eedf7ff7 ("iomap:
> > Remove calls to set and clear folio error flag").
>
> As mentioned last time I actually think this is a bad idea, and the most
> common helpers (mpage_read_folio and block_read_full_folio) will not
> return and error here.
>
>

I'll drop this. I interpreted Matthew's comment to mean the error
return isn't useful for ->readahead but is for ->read_folio.

If iomap_read_folio() doesn't do error returns and always just returns
0, then maybe we should just make it `void iomap_read_folio(...)`
instead of `int iomap_read_folio(...)` then.

Thanks,
Joanne