Re: [PATCH] block/merge: remove unnecessary min() with UINT_MAX

David Laight
2025-02-15T11:51:46Z

On Fri, 14 Feb 2025 12:36:36 -0700
Caleb Sander Mateos <csander@purestorage.com> wrote:

> In bvec_split_segs(), max_bytes is an unsigned, so it must be less than
> or equal to UINT_MAX. Remove the unnecessary min().
>
> Prior to commit 67927d220150 ("block/merge: count bytes instead of
> sectors"), the min() was with UINT_MAX >> 9, so it did have an effect.
>
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
> ---
> block/blk-merge.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index 15cd231d560c..39b738c0e4c9 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -268,11 +268,11 @@ static inline unsigned get_max_segment_size(const struct queue_limits *lim,
> */
> static bool bvec_split_segs(const struct queue_limits *lim,
> const struct bio_vec *bv, unsigned *nsegs, unsigned *bytes,
> unsigned max_segs, unsigned max_bytes)
> {
> - unsigned max_len = min(max_bytes, UINT_MAX) - *bytes;
> + unsigned max_len = max_bytes - *bytes;

More interestingly, what stops *bytes being larger than max_bytes?

David

> unsigned len = min(bv->bv_len, max_len);
> unsigned total_len = 0;
> unsigned seg_size = 0;
>
> while (len && *nsegs < max_segs) {