On Fri, Aug 29, 2025 at 04:56:15PM -0700, Joanne Koong wrote:
> Use the iomap_iter->private field for stashing any read/readahead bios
> instead of defining the bio as part of the iomap_readpage_ctx struct.
> This makes the read/readahead interface more generic. Some filesystems
> that will be using iomap for read/readahead may not have CONFIG_BLOCK
> set.
Sorry, but I don't like abusing iomap_iter::private because (a) it's a
void pointer which means shenanigans; and (b) private exists to store
some private data for an iomap caller, not iomap itself.
> Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
> ---
> fs/iomap/buffered-io.c | 49 +++++++++++++++++++++---------------------
> 1 file changed, 25 insertions(+), 24 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index f2bfb3e17bb0..9db233a4a82c 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -353,11 +353,10 @@ static void iomap_read_end_io(struct bio *bio)
> struct iomap_readpage_ctx {
> struct folio *cur_folio;
> bool folio_unlocked;
> - struct bio *bio;
Does this work if you do:
#ifdef CONFIG_BLOCK
struct bio *bio;
#endif
Hm? Possibly with a forward declaration of struct bio to shut the
compiler up?
--D
> struct readahead_control *rac;
> };
>
> -static void iomap_read_folio_range_async(const struct iomap_iter *iter,
> +static void iomap_read_folio_range_async(struct iomap_iter *iter,
> struct iomap_readpage_ctx *ctx, loff_t pos, size_t plen)
> {
> struct folio *folio = ctx->cur_folio;
> @@ -365,6 +364,7 @@ static void iomap_read_folio_range_async(const struct iomap_iter *iter,
> struct iomap_folio_state *ifs = folio->private;
> size_t poff = offset_in_folio(folio, pos);
> loff_t length = iomap_length(iter);
> + struct bio *bio = iter->private;
> sector_t sector;
>
> ctx->folio_unlocked = true;
> @@ -375,34 +375,32 @@ static void iomap_read_folio_range_async(const struct iomap_iter *iter,
> }
>
> sector = iomap_sector(iomap, pos);
> - if (!ctx->bio ||
> - bio_end_sector(ctx->bio) != sector ||
> - !bio_add_folio(ctx->bio, folio, plen, poff)) {
> + 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 (ctx->bio)
> - submit_bio(ctx->bio);
> + if (bio)
> + submit_bio(bio);
>
> if (ctx->rac) /* same as readahead_gfp_mask */
> gfp |= __GFP_NORETRY | __GFP_NOWARN;
> - ctx->bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs),
> - REQ_OP_READ, gfp);
> + 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 (!ctx->bio) {
> - ctx->bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ,
> - orig_gfp);
> - }
> + if (!bio)
> + bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp);
> + iter->private = bio;
> if (ctx->rac)
> - ctx->bio->bi_opf |= REQ_RAHEAD;
> - ctx->bio->bi_iter.bi_sector = sector;
> - ctx->bio->bi_end_io = iomap_read_end_io;
> - bio_add_folio_nofail(ctx->bio, folio, plen, poff);
> + 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);
> }
> }
>
> @@ -447,15 +445,18 @@ static int iomap_readpage_iter(struct iomap_iter *iter,
> return iomap_iter_advance(iter, &length);
> }
>
> -static void iomap_readfolio_submit(const struct iomap_readpage_ctx *ctx)
> +static void iomap_readfolio_submit(const struct iomap_iter *iter)
> {
> - if (ctx->bio)
> - submit_bio(ctx->bio);
> + struct bio *bio = iter->private;
> +
> + if (bio)
> + submit_bio(bio);
> }
>
> -static void iomap_readfolio_complete(const struct iomap_readpage_ctx *ctx)
> +static void iomap_readfolio_complete(const struct iomap_iter *iter,
> + const struct iomap_readpage_ctx *ctx)
> {
> - iomap_readfolio_submit(ctx);
> + iomap_readfolio_submit(iter);
>
> if (ctx->cur_folio && !ctx->folio_unlocked)
> folio_unlock(ctx->cur_folio);
> @@ -492,7 +493,7 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
> while ((ret = iomap_iter(&iter, ops)) > 0)
> iter.status = iomap_read_folio_iter(&iter, &ctx);
>
> - iomap_readfolio_complete(&ctx);
> + iomap_readfolio_complete(&iter, &ctx);
>
> /*
> * Just like mpage_readahead and block_read_full_folio, we always
> @@ -558,7 +559,7 @@ void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
> while (iomap_iter(&iter, ops) > 0)
> iter.status = iomap_readahead_iter(&iter, &ctx);
>
> - iomap_readfolio_complete(&ctx);
> + iomap_readfolio_complete(&iter, &ctx);
> }
> EXPORT_SYMBOL_GPL(iomap_readahead);
>
> --
> 2.47.3
>
>
