Re: [PATCH v3 03/19] ublk: support UBLK_PARAM_TYPE_INTEGRITY in device creation

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

On Mon, Jan 05, 2026 at 05:57:35PM -0700, Caleb Sander Mateos wrote:
> From: Stanley Zhang <stazhang@purestorage.com>
> 
> Add a feature flag UBLK_F_INTEGRITY for a ublk server to request
> integrity/metadata support when creating a ublk device. The ublk server
> can also check for the feature flag on the created device or the result
> of UBLK_U_CMD_GET_FEATURES to tell if the ublk driver supports it.
> UBLK_F_INTEGRITY requires UBLK_F_USER_COPY, as user copy is the only
> data copy mode initially supported for integrity data.
> Add UBLK_PARAM_TYPE_INTEGRITY and struct ublk_param_integrity to struct
> ublk_params to specify the integrity params of a ublk device.
> UBLK_PARAM_TYPE_INTEGRITY requires UBLK_F_INTEGRITY and a nonzero
> metadata_size. The LBMD_PI_CAP_* and LBMD_PI_CSUM_* values from the
> linux/fs.h UAPI header are used for the flags and csum_type fields.
> If the UBLK_PARAM_TYPE_INTEGRITY flag is set, validate the integrity
> parameters and apply them to the blk_integrity limits.
> 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: drop redundant pi_tuple_size field, use block metadata UAPI
>  constants, add param validation]
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
> ---
>  drivers/block/ublk_drv.c      | 94 ++++++++++++++++++++++++++++++++++-
>  include/uapi/linux/ublk_cmd.h | 18 +++++++
>  2 files changed, 111 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 8e3da9b2b93a..066c6ae062a0 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.
> @@ -628,10 +631,57 @@ 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;
> @@ -690,10 +740,33 @@ 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 (!(ub->dev_info.flags & UBLK_F_INTEGRITY))
> +			return -EINVAL;
> +		if (flags < 0)
> +			return flags;
> +		if (pi_tuple_size < 0)
> +			return pi_tuple_size;
> +		if (!p->metadata_size)
> +			return -EINVAL;
> +		if (p->csum_type == LBMD_PI_CSUM_NONE &&
> +		    p->flags & LBMD_PI_CAP_REFTAG)
> +			return -EINVAL;
> +		if (p->pi_offset + pi_tuple_size > p->metadata_size)
> +			return -EINVAL;
> +		if (p->interval_exp < SECTOR_SHIFT ||
> +		    p->interval_exp > ub->params.basic.logical_bs_shift)
> +			return -EINVAL;
> +	}
> +
>  	return 0;
>  }
>  
>  static void ublk_apply_params(struct ublk_device *ub)
>  {
> @@ -2941,10 +3014,25 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub,
>  		lim.seg_boundary_mask = ub->params.seg.seg_boundary_mask;
>  		lim.max_segment_size = ub->params.seg.max_segment_size;
>  		lim.max_segments = ub->params.seg.max_segments;
>  	}
>  
> +	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);
> +
> +		lim.integrity = (struct blk_integrity) {
> +			.flags = ublk_integrity_flags(p->flags),
> +			.csum_type = ublk_integrity_csum_type(p->csum_type),
> +			.metadata_size = p->metadata_size,
> +			.pi_offset = p->pi_offset,
> +			.interval_exp = p->interval_exp,
> +			.tag_size = p->tag_size,
> +			.pi_tuple_size = pi_tuple_size,
> +		};
> +	}
> +
>  	if (wait_for_completion_interruptible(&ub->completion) != 0)
>  		return -EINTR;
>  
>  	if (ub->ublksrv_tgid != ublksrv_pid)
>  		return -EINVAL;
> @@ -3131,10 +3219,14 @@ static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_cmd *header)
>  		if (info.flags & (UBLK_F_USER_COPY | UBLK_F_SUPPORT_ZERO_COPY |
>  					UBLK_F_AUTO_BUF_REG))
>  			return -EINVAL;
>  	}
>  
> +	/* User copy is required to access integrity buffer */
> +	if (info.flags & UBLK_F_INTEGRITY && !(info.flags & UBLK_F_USER_COPY))
> +		return -EINVAL;
> +
>  	/* the created device is always owned by current user */
>  	ublk_store_owner_uid_gid(&info.owner_uid, &info.owner_gid);
>  
>  	if (header->dev_id != info.dev_id) {
>  		pr_warn("%s: dev id not match %u %u\n",
> diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
> index ec77dabba45b..a54c47832fa2 100644
> --- a/include/uapi/linux/ublk_cmd.h
> +++ b/include/uapi/linux/ublk_cmd.h
> @@ -309,10 +309,16 @@
>   * the I/O's daemon task. The q_id and tag of the registered buffer are required
>   * in UBLK_U_IO_UNREGISTER_IO_BUF's ublksrv_io_cmd.
>   */
>  #define UBLK_F_BUF_REG_OFF_DAEMON (1ULL << 14)
>  
> +/*
> + * ublk device supports requests with integrity/metadata buffer.
> + * Requires UBLK_F_USER_COPY.
> + */
> +#define UBLK_F_INTEGRITY (1ULL << 16)
> +
>  /* device state */
>  #define UBLK_S_DEV_DEAD	0
>  #define UBLK_S_DEV_LIVE	1
>  #define UBLK_S_DEV_QUIESCED	2
>  #define UBLK_S_DEV_FAIL_IO 	3
> @@ -598,10 +604,20 @@ struct ublk_param_segment {
>  	__u32 	max_segment_size;
>  	__u16 	max_segments;
>  	__u8	pad[2];
>  };
>  
> +struct ublk_param_integrity {
> +	__u32	flags; /* LBMD_PI_CAP_* from linux/fs.h */
> +	__u8	interval_exp;
> +	__u8	metadata_size; /* UBLK_PARAM_TYPE_INTEGRITY requires nonzero */
> +	__u8	pi_offset;
> +	__u8	csum_type; /* LBMD_PI_CSUM_* from linux/fs.h */
> +	__u8	tag_size;
> +	__u8	pad[7];
> +};

Looks max_integrity_segments is missed, otherwise this patch is fine for me.


Thanks,
Ming