[PATCH v3 03/15] iomap: store read/readahead bio generically

Joanne Koong
2025-09-16T23:50:32Z

Store the iomap_readpage_ctx bio generically as a "void *read_ctx".
This makes the read/readahead interface more generic, which allows it to
be used by filesystems that may not be block-based and may not have
CONFIG_BLOCK set.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
---
fs/iomap/buffered-io.c | 29 ++++++++++++++---------------
1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index ee96558b6d99..2a1709e0757b 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -353,13 +353,13 @@ static void iomap_read_end_io(struct bio *bio)
struct iomap_readpage_ctx {
struct folio *cur_folio;
bool cur_folio_in_bio;
- struct bio *bio;
+ void *read_ctx;
struct readahead_control *rac;
};

static void iomap_bio_submit_read(struct iomap_readpage_ctx *ctx)
{
- struct bio *bio = ctx->bio;
+ struct bio *bio = ctx->read_ctx;

if (bio)
submit_bio(bio);
@@ -374,6 +374,7 @@ static void iomap_bio_read_folio_range(const struct iomap_iter *iter,
size_t poff = offset_in_folio(folio, pos);
loff_t length = iomap_length(iter);
sector_t sector;
+ struct bio *bio = ctx->read_ctx;

ctx->cur_folio_in_bio = true;
if (ifs) {
@@ -383,9 +384,8 @@ static void iomap_bio_read_folio_range(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);
@@ -394,22 +394,21 @@ static void iomap_bio_read_folio_range(const struct iomap_iter *iter,

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);
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);
+ ctx->read_ctx = bio;
}
}

--
2.47.3