Re: [PATCH 12/15] iomap: add a bioset pointer to iomap_read_folio_ops

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Jan 21, 2026 at 07:43:20AM +0100, Christoph Hellwig wrote:
> Optionally allocate the bio from the bioset provided in
> iomap_read_folio_ops.  If no bioset is provided, fs_bio_set is still
> used, which is the standard bioset for file systems.
> 
> Based on a patch from Goldwyn Rodrigues <rgoldwyn@suse.com>.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks reasonable,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/iomap/bio.c        | 14 ++++++++++++--
>  include/linux/iomap.h |  6 ++++++
>  2 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/iomap/bio.c b/fs/iomap/bio.c
> index 903cb9fe759e..259a2bf95a43 100644
> --- a/fs/iomap/bio.c
> +++ b/fs/iomap/bio.c
> @@ -24,11 +24,19 @@ static void iomap_bio_submit_read(const struct iomap_iter *iter,
>  	submit_bio(ctx->read_ctx);
>  }
>  
> +static struct bio_set *iomap_read_bio_set(struct iomap_read_folio_ctx *ctx)
> +{
> +	if (ctx->ops && ctx->ops->bio_set)
> +		return ctx->ops->bio_set;
> +	return &fs_bio_set;
> +}
> +
>  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 bio_set *bio_set = iomap_read_bio_set(ctx);
>  	struct folio *folio = ctx->cur_folio;
>  	gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
>  	gfp_t orig_gfp = gfp;
> @@ -47,9 +55,11 @@ static void iomap_read_alloc_bio(const struct iomap_iter *iter,
>  	 * 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);
> +	bio = bio_alloc_bioset(iomap->bdev, bio_max_segs(nr_vecs), REQ_OP_READ,
> +			gfp, bio_set);
>  	if (!bio)
> -		bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp);
> +		bio = bio_alloc_bioset(iomap->bdev, 1, REQ_OP_READ, orig_gfp,
> +				bio_set);
>  	if (ctx->rac)
>  		bio->bi_opf |= REQ_RAHEAD;
>  	bio->bi_iter.bi_sector = iomap_sector(iomap, iter->pos);
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index b3f545d41720..24f884b6b0c4 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -515,6 +515,12 @@ struct iomap_read_ops {
>  	 */
>  	void (*submit_read)(const struct iomap_iter *iter,
>  			struct iomap_read_folio_ctx *ctx);
> +
> +	/*
> +	 * 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;
>  };
>  
>  /*
> -- 
> 2.47.3
> 
>