Re: [PATCH 06/20] ublk: support UBLK_PARAM_TYPE_INTEGRITY in device creation

[Ming Lei <ming.lei@redhat.com>]

On Mon, Dec 22, 2025 at 10:35:27AM -0500, Caleb Sander Mateos wrote:
> On Mon, Dec 22, 2025 at 9:47 AM Ming Lei <ming.lei@redhat.com> wrote:
> >
> > On Tue, Dec 16, 2025 at 10:34:40PM -0700, Caleb Sander Mateos wrote:
> > > From: Stanley Zhang <stazhang@purestorage.com>
> > >
> > > If the UBLK_PARAM_TYPE_INTEGRITY flag is set, validate the integrity
> > > parameters and apply them to the blk_integrity limits.
> > > UBLK_PARAM_TYPE_INTEGRITY requires CONFIG_BLK_DEV_INTEGRITY=y,
> > > UBLK_F_USER_COPY, and metadata_size > 0. Reuse the block metadata ioctl
> > > LBMD_PI_CAP_* and LBMD_PI_CSUM_* constants from the linux/fs.h UAPI
> > > header for the flags and csum_type field values.
> > > The struct ublk_param_integrity validations are based on the checks in
> > > blk_validate_integrity_limits(). Any invalid parameters should be
> > > rejected before being applied to struct blk_integrity.
> > >
> > > Signed-off-by: Stanley Zhang <stazhang@purestorage.com>
> > > [csander: add param validation]
> > > Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
> > > ---
> > >  drivers/block/ublk_drv.c | 92 +++++++++++++++++++++++++++++++++++++++-
> > >  1 file changed, 91 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> > > index 4da5d8ff1e1d..2893a9172220 100644
> > > --- a/drivers/block/ublk_drv.c
> > > +++ b/drivers/block/ublk_drv.c
> > > @@ -42,10 +42,12 @@
> > >  #include <linux/mm.h>
> > >  #include <asm/page.h>
> > >  #include <linux/task_work.h>
> > >  #include <linux/namei.h>
> > >  #include <linux/kref.h>
> > > +#include <linux/blk-integrity.h>
> > > +#include <uapi/linux/fs.h>
> > >  #include <uapi/linux/ublk_cmd.h>
> > >
> > >  #define UBLK_MINORS          (1U << MINORBITS)
> > >
> > >  #define UBLK_INVALID_BUF_IDX         ((u16)-1)
> > > @@ -81,11 +83,12 @@
> > >
> > >  /* All UBLK_PARAM_TYPE_* should be included here */
> > >  #define UBLK_PARAM_TYPE_ALL                                \
> > >       (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD | \
> > >        UBLK_PARAM_TYPE_DEVT | UBLK_PARAM_TYPE_ZONED |    \
> > > -      UBLK_PARAM_TYPE_DMA_ALIGN | UBLK_PARAM_TYPE_SEGMENT)
> > > +      UBLK_PARAM_TYPE_DMA_ALIGN | UBLK_PARAM_TYPE_SEGMENT | \
> > > +      UBLK_PARAM_TYPE_INTEGRITY)
> > >
> > >  struct ublk_uring_cmd_pdu {
> > >       /*
> > >        * Store requests in same batch temporarily for queuing them to
> > >        * daemon context.
> > > @@ -613,10 +616,57 @@ static void ublk_dev_param_basic_apply(struct ublk_device *ub)
> > >               set_disk_ro(ub->ub_disk, true);
> > >
> > >       set_capacity(ub->ub_disk, p->dev_sectors);
> > >  }
> > >
> > > +static int ublk_integrity_flags(u32 flags)
> > > +{
> > > +     int ret_flags = 0;
> > > +
> > > +     if (flags & LBMD_PI_CAP_INTEGRITY) {
> > > +             flags &= ~LBMD_PI_CAP_INTEGRITY;
> > > +             ret_flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
> > > +     }
> > > +     if (flags & LBMD_PI_CAP_REFTAG) {
> > > +             flags &= ~LBMD_PI_CAP_REFTAG;
> > > +             ret_flags |= BLK_INTEGRITY_REF_TAG;
> > > +     }
> > > +     return flags ? -EINVAL : ret_flags;
> > > +}
> > > +
> > > +static int ublk_integrity_pi_tuple_size(u8 csum_type)
> > > +{
> > > +     switch (csum_type) {
> > > +     case LBMD_PI_CSUM_NONE:
> > > +             return 0;
> > > +     case LBMD_PI_CSUM_IP:
> > > +     case LBMD_PI_CSUM_CRC16_T10DIF:
> > > +             return 8;
> > > +     case LBMD_PI_CSUM_CRC64_NVME:
> > > +             return 16;
> > > +     default:
> > > +             return -EINVAL;
> > > +     }
> > > +}
> > > +
> > > +static enum blk_integrity_checksum ublk_integrity_csum_type(u8 csum_type)
> > > +{
> > > +     switch (csum_type) {
> > > +     case LBMD_PI_CSUM_NONE:
> > > +             return BLK_INTEGRITY_CSUM_NONE;
> > > +     case LBMD_PI_CSUM_IP:
> > > +             return BLK_INTEGRITY_CSUM_IP;
> > > +     case LBMD_PI_CSUM_CRC16_T10DIF:
> > > +             return BLK_INTEGRITY_CSUM_CRC;
> > > +     case LBMD_PI_CSUM_CRC64_NVME:
> > > +             return BLK_INTEGRITY_CSUM_CRC64;
> > > +     default:
> > > +             WARN_ON_ONCE(1);
> > > +             return BLK_INTEGRITY_CSUM_NONE;
> > > +     }
> > > +}
> > > +
> > >  static int ublk_validate_params(const struct ublk_device *ub)
> > >  {
> > >       /* basic param is the only one which must be set */
> > >       if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
> > >               const struct ublk_param_basic *p = &ub->params.basic;
> > > @@ -675,10 +725,35 @@ static int ublk_validate_params(const struct ublk_device *ub)
> > >                       return -EINVAL;
> > >               if (p->max_segment_size < UBLK_MIN_SEGMENT_SIZE)
> > >                       return -EINVAL;
> > >       }
> > >
> > > +     if (ub->params.types & UBLK_PARAM_TYPE_INTEGRITY) {
> > > +             const struct ublk_param_integrity *p = &ub->params.integrity;
> > > +             int pi_tuple_size = ublk_integrity_pi_tuple_size(p->csum_type);
> > > +             int flags = ublk_integrity_flags(p->flags);
> > > +
> > > +             if (!IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY))
> > > +                     return -EINVAL;
> > > +             if (!ublk_dev_support_user_copy(ub))
> > > +                     return -EINVAL;
> >
> > UBLK_IO_F_INTEGRITY should be checked here, and ublk_dev_support_user_copy() can be
> > validated with UBLK_IO_F_INTEGRITY together in ublk_ctrl_add_dev(), so
> > mis-matched features can be failed earlier.
> 
> I'm not sure what you mean. UBLK_IO_F_INTEGRITY is a per-I/O flag set

I misread it as feature flag of `UBLK_F_INTEGRITY`...

> in struct ublksrv_io_desc's op_flags field. Are you suggesting adding
> a separate feature flag for integrity? I can do that, but I didn't
> originally because none of the other UBLK_PARAM_TYPE_* flags have
> associated features.

oops, you don't define feature flag of UBLK_F_INTEGRITY, then how can
userspace know UBLK INTEGRITY is supported by driver?

With UBLK_F_INTEGRITY you can run early check in ublk_ctrl_add_dev() for:

- dependency on user copy
- if kernel enables CONFIG_BLK_DEV_INTEGRITY

> 
> >
> > Same for IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY).
> >
> > > +             if (flags < 0)
> > > +                     return flags;
> > > +             if (pi_tuple_size < 0)
> > > +                     return pi_tuple_size;
> > > +             if (!p->metadata_size)
> > > +                     return -EINVAL;
> >
> > blk_validate_integrity_limits() allows zero p->metadata_size with
> > LBMD_PI_CSUM_NONE, maybe document ublk's support for zero metadata_size & LBMD_PI_CSUM_NONE?
> 
> Sure, I can mention that UBLK_PARAM_TYPE_INTEGRITY requires a nonzero
> metadata size. Would you prefer that metadata_size == 0 be supported?
> It would be a bit more code, but certainly possible.

It can be started with less feature/functions, and can be extended in future.


Thanks,
Ming