On Mon, Feb 03, 2025 at 10:43:07AM +0100, Christoph Hellwig wrote:
> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>
> Allocate the bio from the bioset provided in iomap_read_folio_ops.
> If no bioset is provided, fs_bio_set is used which is the standard
> bioset for filesystems.
>
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
I feel like I've seen this patch and the last one floating around for
quite a while; would you and/or Goldwyn like to merge it for 6.15?
--D
> [hch: factor out two helpers]
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/iomap/buffered-io.c | 51 ++++++++++++++++++++++++++++--------------
> include/linux/iomap.h | 6 +++++
> 2 files changed, 40 insertions(+), 17 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 804527dcc9ba..eaffa23eb8e4 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -364,6 +364,39 @@ static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
> pos >= i_size_read(iter->inode);
> }
>
> +static struct bio_set *iomap_read_bio_set(struct iomap_readpage_ctx *ctx)
> +{
> + if (ctx->ops && ctx->ops->bio_set)
> + return ctx->ops->bio_set;
> + return &fs_bio_set;
> +}
> +
> +static struct bio *iomap_read_alloc_bio(const struct iomap_iter *iter,
> + struct iomap_readpage_ctx *ctx, loff_t length)
> +{
> + unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
> + struct block_device *bdev = iter->iomap.bdev;
> + struct bio_set *bio_set = iomap_read_bio_set(ctx);
> + gfp_t gfp = mapping_gfp_constraint(iter->inode->i_mapping, GFP_KERNEL);
> + gfp_t orig_gfp = gfp;
> + struct bio *bio;
> +
> + if (ctx->rac) /* same as readahead_gfp_mask */
> + gfp |= __GFP_NORETRY | __GFP_NOWARN;
> +
> + bio = bio_alloc_bioset(bdev, bio_max_segs(nr_vecs), REQ_OP_READ, gfp,
> + bio_set);
> +
> + /*
> + * 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_bioset(bdev, 1, REQ_OP_READ, orig_gfp, bio_set);
> + return bio;
> +}
> +
> static void iomap_read_submit_bio(const struct iomap_iter *iter,
> struct iomap_readpage_ctx *ctx)
> {
> @@ -411,27 +444,11 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
> if (!ctx->bio ||
> bio_end_sector(ctx->bio) != sector ||
> !bio_add_folio(ctx->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)
> iomap_read_submit_bio(iter, ctx);
>
> ctx->bio_start_pos = offset;
> - 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);
> - /*
> - * 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);
> - }
> + ctx->bio = iomap_read_alloc_bio(iter, ctx, length);
> if (ctx->rac)
> ctx->bio->bi_opf |= REQ_RAHEAD;
> ctx->bio->bi_iter.bi_sector = sector;
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index 2930861d1ef1..304be88ecd23 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -311,6 +311,12 @@ struct iomap_read_folio_ops {
> */
> void (*submit_io)(struct inode *inode, struct bio *bio,
> loff_t file_offset);
> +
> + /*
> + * Optional, allows filesystem to specify own bio_set, so new bio's
> + * can be allocated from the provided bio_set.
> + */
> + struct bio_set *bio_set;
> };
>
> int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops,
> --
> 2.45.2
>
>
