> -static int iomap_read_folio_sync(loff_t block_start, struct folio *folio,
> - size_t poff, size_t plen, const struct iomap *iomap)
> +static int iomap_read_folio_sync(const struct iomap_iter *iter, loff_t block_start,
> + struct folio *folio, size_t poff, size_t plen)
> {
> - return iomap_bio_read_folio_sync(block_start, folio, poff, plen, iomap);
> + const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
> + const struct iomap *srcmap = iomap_iter_srcmap(iter);
> +
> + if (folio_ops && folio_ops->read_folio_sync)
> + return folio_ops->read_folio_sync(block_start, folio,
> + poff, plen, srcmap,
> + iter->private);
> +
> + /* IOMAP_IN_MEM iomaps must always handle ->read_folio_sync() */
> + WARN_ON_ONCE(iter->iomap.type == IOMAP_IN_MEM);
> +
> + return iomap_bio_read_folio_sync(block_start, folio, poff, plen, srcmap);
I just ran into this for another project and I hated my plumbing for
this. I hate yours very slightly less but I still don't like it.
This is really more of a VM level concept, so I wonder if we should
instead:
- add a new read_folio_sync method to the address space operations that
reads a folio without unlocking it.
- figure out if just reading the head/tail really is as much of an
optimization, and if it it pass arguments to it to just read the
head/tail, and if not skip it.
