On Wed, Nov 20, 2024 at 12:38:41AM -0800, Christoph Hellwig wrote:
> On Tue, Nov 19, 2024 at 10:46:53AM -0500, Brian Foster wrote:
> > To facilitate batch processing of dirty folios for zero range, tweak
> > the write begin path to allow the caller to optionally pass in its
> > own folio/pos combination.
> >
> > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
> > ---
> > fs/iomap/buffered-io.c | 20 +++++++++++++-------
> > 1 file changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> > index ce73d2a48c1e..d1a86aea1a7a 100644
> > --- a/fs/iomap/buffered-io.c
> > +++ b/fs/iomap/buffered-io.c
> > @@ -781,7 +781,7 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
> > {
> > const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
> > const struct iomap *srcmap = iomap_iter_srcmap(iter);
> > - struct folio *folio;
> > + struct folio *folio = *foliop;
> > int status = 0;
> >
> > BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
> > @@ -794,9 +794,15 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
> > if (!mapping_large_folio_support(iter->inode->i_mapping))
> > len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
> >
> > - folio = __iomap_get_folio(iter, pos, len);
> > - if (IS_ERR(folio))
> > - return PTR_ERR(folio);
> > + /*
> > + * XXX: Might want to plumb batch handling down through here. For now
> > + * let the caller do it.
>
> Yeah, plumbing in the batch here would be nicer.
>
Ok, I'll take a closer look at that. IIRC I punted on it initially
because we'll also have to fix up pos/len down in this path when the
next folio is not contiguous. This was easier to just get the basics
working.
Brian
> I suspect doing batch processing might actually be a neat thing for
> the normal write patch as well.
>
