linux-kernel - Re: [PATCH v4 1/2] block: decouple secure erase size limit from discard size limit

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Message-ID: <CAPDyKFrnbvkp2_WP837-nsTZN5vatKifETihn-y+YQ1=DjbADQ@mail.gmail.com>
Date: Wed, 4 Feb 2026 15:33:17 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: ziniu.wang_1@....com, axboe@...nel.dk
Cc: hch@...radead.org, linux-block@...r.kernel.org, linux-mmc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [PATCH v4 1/2] block: decouple secure erase size limit from
 discard size limit

On Wed, 4 Feb 2026 at 04:37, <ziniu.wang_1@....com> wrote:
>
> From: Luke Wang <ziniu.wang_1@....com>
>
> Secure erase should use max_secure_erase_sectors instead of being limited
> by max_discard_sectors. Separate the handling of REQ_OP_SECURE_ERASE from
> REQ_OP_DISCARD to allow each operation to use its own size limit.
>
> Signed-off-by: Luke Wang <ziniu.wang_1@....com>

As I said before, I don't know this code in great detail, but FWIW,
feel free to add:

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Jens, please funnel the patch1 via your blk tree. I have already
picked the mmc patch (patch2) via my mmc tree.

Kind regards
Uffe

> ---
>  block/blk-merge.c | 21 +++++++++++++++++----
>  block/blk.h       |  6 +++++-
>  2 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index 0eb0aef97197..fcf09325b22e 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -158,8 +158,9 @@ static struct bio *bio_submit_split(struct bio *bio, int split_sectors)
>         return bio;
>  }
>
> -struct bio *bio_split_discard(struct bio *bio, const struct queue_limits *lim,
> -               unsigned *nsegs)
> +static struct bio *__bio_split_discard(struct bio *bio,
> +               const struct queue_limits *lim, unsigned *nsegs,
> +               unsigned int max_sectors)
>  {
>         unsigned int max_discard_sectors, granularity;
>         sector_t tmp;
> @@ -169,8 +170,7 @@ struct bio *bio_split_discard(struct bio *bio, const struct queue_limits *lim,
>
>         granularity = max(lim->discard_granularity >> 9, 1U);
>
> -       max_discard_sectors =
> -               min(lim->max_discard_sectors, bio_allowed_max_sectors(lim));
> +       max_discard_sectors = min(max_sectors, bio_allowed_max_sectors(lim));
>         max_discard_sectors -= max_discard_sectors % granularity;
>         if (unlikely(!max_discard_sectors))
>                 return bio;
> @@ -194,6 +194,19 @@ struct bio *bio_split_discard(struct bio *bio, const struct queue_limits *lim,
>         return bio_submit_split(bio, split_sectors);
>  }
>
> +struct bio *bio_split_discard(struct bio *bio, const struct queue_limits *lim,
> +               unsigned *nsegs)
> +{
> +       unsigned int max_sectors;
> +
> +       if (bio_op(bio) == REQ_OP_SECURE_ERASE)
> +               max_sectors = lim->max_secure_erase_sectors;
> +       else
> +               max_sectors = lim->max_discard_sectors;
> +
> +       return __bio_split_discard(bio, lim, nsegs, max_sectors);
> +}
> +
>  static inline unsigned int blk_boundary_sectors(const struct queue_limits *lim,
>                                                 bool is_atomic)
>  {
> diff --git a/block/blk.h b/block/blk.h
> index 886238cae5f1..a6b1de509733 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -208,10 +208,14 @@ static inline unsigned int blk_queue_get_max_sectors(struct request *rq)
>         struct request_queue *q = rq->q;
>         enum req_op op = req_op(rq);
>
> -       if (unlikely(op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE))
> +       if (unlikely(op == REQ_OP_DISCARD))
>                 return min(q->limits.max_discard_sectors,
>                            UINT_MAX >> SECTOR_SHIFT);
>
> +       if (unlikely(op == REQ_OP_SECURE_ERASE))
> +               return min(q->limits.max_secure_erase_sectors,
> +                          UINT_MAX >> SECTOR_SHIFT);
> +
>         if (unlikely(op == REQ_OP_WRITE_ZEROES))
>                 return q->limits.max_write_zeroes_sectors;
>
> --
> 2.34.1
>