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iomap: refactor iomap_bio_read_folio_range

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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 <hch@lst.de>
Link: https://patch.msgid.link/20260223132021.292832-9-hch@lst.de
Tested-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christoph Hellwig 2026-02-23 05:20:08 -08:00 committed by Christian Brauner
parent 969ebebc30
commit 2580a0095f
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GPG Key ID: 91C61BC06578DCA2
1 changed files with 38 additions and 33 deletions
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71
fs/iomap/bio.c
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@ -26,45 +26,50 @@ static void iomap_bio_submit_read(struct iomap_read_folio_ctx *ctx)
submit_bio(bio);
}
static void iomap_read_alloc_bio(const struct iomap_iter *iter,
struct iomap_read_folio_ctx *ctx, size_t plen)
{
const struct iomap *iomap = &iter->iomap;
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;
if (bio)
submit_bio(bio);
/* Same as readahead_gfp_mask: */
if (ctx->rac)
gfp |= __GFP_NORETRY | __GFP_NOWARN;
/*
* 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;
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;
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);
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;
}