linux-kernel - RE: [EXT] Re: [PATCH v3 1/2] block: decouple secure erase size limit from discard size limit

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Message-ID:
 <DU2PR04MB85671D007A045527195EC5F9ED98A@DU2PR04MB8567.eurprd04.prod.outlook.com>
Date: Wed, 4 Feb 2026 02:28:52 +0000
From: Luke Wang <ziniu.wang_1@....com>
To: Ulf Hansson <ulf.hansson@...aro.org>
CC: "axboe@...nel.dk" <axboe@...nel.dk>, "hch@...radead.org"
	<hch@...radead.org>, "linux-block@...r.kernel.org"
	<linux-block@...r.kernel.org>, "linux-mmc@...r.kernel.org"
	<linux-mmc@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: RE: [EXT] Re: [PATCH v3 1/2] block: decouple secure erase size limit
 from discard size limit



> -----Original Message-----
> From: Ulf Hansson <ulf.hansson@...aro.org>
> Sent: Tuesday, February 3, 2026 7:55 PM
> To: Luke Wang <ziniu.wang_1@....com>
> Cc: axboe@...nel.dk; hch@...radead.org; linux-block@...r.kernel.org; linux-
> mmc@...r.kernel.org; linux-kernel@...r.kernel.org; imx@...ts.linux.dev
> Subject: [EXT] Re: [PATCH v3 1/2] block: decouple secure erase size limit from
> discard size limit
> 
> Caution: This is an external email. Please take care when clicking links or
> opening attachments. When in doubt, report the message using the 'Report this
> email' button
> 
> 
> On Tue, 3 Feb 2026 at 11:27, <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.
> 
> I don't know this code well enough, but is this change really sufficient?
> 
> Don't we need to adjust blk_queue_get_max_sectors() as well?

Oh, I focus on the helper function and forget to adjust blk_queue_get_max_sectors()
I will add this change back.

Thanks
Luke

> 
> Kind regards
> Uffe
> 
> >
> > Signed-off-by: Luke Wang <ziniu.wang_1@....com>
> > ---
> >  block/blk-merge.c | 21 +++++++++++++++++----
> >  1 file changed, 17 insertions(+), 4 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)
> >  {
> > --
> > 2.34.1
> >