On Wed, Jan 21, 2026 at 07:43:16AM +0100, Christoph Hellwig wrote: > Split out the logic to allocate a new bio and only keep the fast path > that adds more data to an existing bio in iomap_bio_read_folio_range. > > Signed-off-by: Christoph Hellwig <[email protected]>
Looks like a simple function split to me... Reviewed-by: "Darrick J. Wong" <[email protected]> --D > --- > fs/iomap/bio.c | 69 +++++++++++++++++++++++++++----------------------- > 1 file changed, 37 insertions(+), 32 deletions(-) > > diff --git a/fs/iomap/bio.c b/fs/iomap/bio.c > index fc045f2e4c45..578b1202e037 100644 > --- a/fs/iomap/bio.c > +++ b/fs/iomap/bio.c > @@ -26,45 +26,50 @@ static void iomap_bio_submit_read(struct > iomap_read_folio_ctx *ctx) > submit_bio(bio); > } > > -static int iomap_bio_read_folio_range(const struct iomap_iter *iter, > +static void iomap_read_alloc_bio(const struct iomap_iter *iter, > struct iomap_read_folio_ctx *ctx, size_t plen) > { > - struct folio *folio = ctx->cur_folio; > const struct iomap *iomap = &iter->iomap; > - loff_t pos = iter->pos; > - size_t poff = offset_in_folio(folio, pos); > - loff_t length = iomap_length(iter); > - sector_t sector; > + unsigned int nr_vecs = DIV_ROUND_UP(iomap_length(iter), PAGE_SIZE); > + struct folio *folio = ctx->cur_folio; > + gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL); > + gfp_t orig_gfp = gfp; > struct bio *bio = ctx->read_ctx; > > - sector = iomap_sector(iomap, pos); > - if (!bio || bio_end_sector(bio) != sector || > - !bio_add_folio(bio, folio, plen, poff)) { > - gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL); > - gfp_t orig_gfp = gfp; > - unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE); > + if (bio) > + submit_bio(bio); > + > + /* Same as readahead_gfp_mask: */ > + if (ctx->rac) > + gfp |= __GFP_NORETRY | __GFP_NOWARN; > > - if (bio) > - submit_bio(bio); > + /* > + * If the bio_alloc fails, try it again for a single page to avoid > + * having to deal with partial page reads. This emulates what > + * do_mpage_read_folio does. > + */ > + bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs), REQ_OP_READ, gfp); > + if (!bio) > + bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp); > + if (ctx->rac) > + bio->bi_opf |= REQ_RAHEAD; > + bio->bi_iter.bi_sector = iomap_sector(iomap, iter->pos); > + bio->bi_end_io = iomap_read_end_io; > + bio_add_folio_nofail(bio, folio, plen, > + offset_in_folio(folio, iter->pos)); > + ctx->read_ctx = bio; > +} > + > +static int iomap_bio_read_folio_range(const struct iomap_iter *iter, > + struct iomap_read_folio_ctx *ctx, size_t plen) > +{ > + struct folio *folio = ctx->cur_folio; > + struct bio *bio = ctx->read_ctx; > > - if (ctx->rac) /* same as readahead_gfp_mask */ > - gfp |= __GFP_NORETRY | __GFP_NOWARN; > - bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs), REQ_OP_READ, > - gfp); > - /* > - * If the bio_alloc fails, try it again for a single page to > - * avoid having to deal with partial page reads. This emulates > - * what do_mpage_read_folio does. > - */ > - if (!bio) > - bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp); > - if (ctx->rac) > - bio->bi_opf |= REQ_RAHEAD; > - bio->bi_iter.bi_sector = sector; > - bio->bi_end_io = iomap_read_end_io; > - bio_add_folio_nofail(bio, folio, plen, poff); > - ctx->read_ctx = bio; > - } > + if (!bio || > + bio_end_sector(bio) != iomap_sector(&iter->iomap, iter->pos) || > + !bio_add_folio(bio, folio, plen, offset_in_folio(folio, iter->pos))) > + iomap_read_alloc_bio(iter, ctx, plen); > return 0; > } > > -- > 2.47.3 > >
