[PATCH v2] block: Correct comments on bio_alloc_clone() and bio_init_clone()

[PATCH v2] block: Correct comments on bio_alloc_clone() and bio_init_clone()

[John Garry]

Correct the comments that the cloned bio must be freed before the memory
pointed to by @bio_Src->bi_io_vecs (is freed).

Christoph Hellwig contributed most the of the update wording.

Signed-off-by: John Garry <john.g.garry@oracle.com>

diff --git a/block/bio.c b/block/bio.c
index 8203bb7455a9f..156bb75f55298 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -897,10 +897,11 @@ static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp)
  * @gfp: allocation priority
  * @bs: bio_set to allocate from
  *
- * Allocate a new bio that is a clone of @bio_src. The caller owns the returned
- * bio, but not the actual data it points to.
- *
- * The caller must ensure that the return bio is not freed before @bio_src.
+ * Allocate a new bio that is a clone of @bio_src. This reuses the bio_vecs
+ * pointed to by @bio_src->bi_io_vec, and clones the iterator pointing to
+ * the current position in it.  The caller owns the returned bio, but not
+ * the bio_vecs, and must ensure the bio is freed before the memory
+ * pointed to by @bio_Src->bi_io_vecs.
  */
 struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
 		gfp_t gfp, struct bio_set *bs)
@@ -929,9 +930,7 @@ EXPORT_SYMBOL(bio_alloc_clone);
  * @gfp: allocation priority
  *
  * Initialize a new bio in caller provided memory that is a clone of @bio_src.
- * The caller owns the returned bio, but not the actual data it points to.
- *
- * The caller must ensure that @bio_src is not freed before @bio.
+ * The same bio_vecs reuse and bio lifetime rules as bio_alloc_clone() apply.
  */
 int bio_init_clone(struct block_device *bdev, struct bio *bio,
 		struct bio *bio_src, gfp_t gfp)
-- 
2.43.5

Re: [PATCH v2] block: Correct comments on bio_alloc_clone() and bio_init_clone()

[Damien Le Moal]

On 2/27/26 19:44, John Garry wrote:
> Correct the comments that the cloned bio must be freed before the memory
> pointed to by @bio_Src->bi_io_vecs (is freed).
> 
> Christoph Hellwig contributed most the of the update wording.
> 
> Signed-off-by: John Garry <john.g.garry@oracle.com>

Looks good to me.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

Note: Not sure if it matters, but your patch is missing the "---" separator
between your SoB and the beginning of the diff.

> 
> diff --git a/block/bio.c b/block/bio.c
> index 8203bb7455a9f..156bb75f55298 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -897,10 +897,11 @@ static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp)
>   * @gfp: allocation priority
>   * @bs: bio_set to allocate from
>   *
> - * Allocate a new bio that is a clone of @bio_src. The caller owns the returned
> - * bio, but not the actual data it points to.
> - *
> - * The caller must ensure that the return bio is not freed before @bio_src.
> + * Allocate a new bio that is a clone of @bio_src. This reuses the bio_vecs
> + * pointed to by @bio_src->bi_io_vec, and clones the iterator pointing to
> + * the current position in it.  The caller owns the returned bio, but not
> + * the bio_vecs, and must ensure the bio is freed before the memory
> + * pointed to by @bio_Src->bi_io_vecs.
>   */
>  struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
>  		gfp_t gfp, struct bio_set *bs)
> @@ -929,9 +930,7 @@ EXPORT_SYMBOL(bio_alloc_clone);
>   * @gfp: allocation priority
>   *
>   * Initialize a new bio in caller provided memory that is a clone of @bio_src.
> - * The caller owns the returned bio, but not the actual data it points to.
> - *
> - * The caller must ensure that @bio_src is not freed before @bio.
> + * The same bio_vecs reuse and bio lifetime rules as bio_alloc_clone() apply.
>   */
>  int bio_init_clone(struct block_device *bdev, struct bio *bio,
>  		struct bio *bio_src, gfp_t gfp)


-- 
Damien Le Moal
Western Digital Research

Re: [PATCH v2] block: Correct comments on bio_alloc_clone() and bio_init_clone()

[Christoph Hellwig]

> + * pointed to by @bio_Src->bi_io_vecs.

s/bio_Src/bio_src/

Re: [PATCH v2] block: Correct comments on bio_alloc_clone() and bio_init_clone()

[Jens Axboe]

On Fri, 27 Feb 2026 10:44:38 +0000, John Garry wrote:
> Correct the comments that the cloned bio must be freed before the memory
> pointed to by @bio_Src->bi_io_vecs (is freed).
> 
> Christoph Hellwig contributed most the of the update wording.
> 
> 

Applied, thanks!

[1/1] block: Correct comments on bio_alloc_clone() and bio_init_clone()
      commit: 6d13f8ca6428fd5c24f5d83da37a8f297419d273

Best regards,
-- 
Jens Axboe