[PATCH for-next v4 0/4] add ioctl to query metadata and protection info capabilities

[PATCH for-next v4 0/4] add ioctl to query metadata and protection info capabilities

[Anuj Gupta]

Hi all,

This patch series adds a new ioctl to query metadata and integrity
capability.

Patch 1 renames tuple_size field to metadata_size
Patch_2 adds a pi_tuple_size field in blk_integrity struct which is later
used to export this value to the user as well.
Patch 3 allows computing right pi_offset value.
Patch 4 introduces a new ioctl to query integrity capability.

v3->v4
rename tuple_size to metadata_size to inflect right meaning (Martin)
rectify the condition in blk_validate_integrity_limits when csum type is
none (Christoph)
change uapi field comment to more friendly formats (Christoph)
add comments regarding ioctl behaviour when bi is NULL (Christoph)
remove the reserved fields and use different scheme for extensibility
(Christian)
Other misc code improvements (Christoph)
set pi_tuple_size and pi_offset in NVMe only if csum type is not NONE

v2->v3
better naming for uapi struct fields (Martin)
validate integrity fields in blk-settings.c (Christoph)

v1 -> v2
introduce metadata_size, storage_tag_size and ref_tag_size field in the
uapi struct (Martin)
uapi struct fields comment improvements (Martin)
add csum_type definitions to the uapi file (Martin)
add fpc_* prefix to uapi struct fields (Andreas)
bump the size of rsvd and hence the uapi struct to 32 bytes (Andreas)
use correct value for ioctl (Andreas)
use clearer names for CRC (Eric)


Anuj Gupta (4):
  block: rename tuple_size field in blk_integrity to metadata_size
  block: introduce pi_tuple_size field in blk_integrity
  set pi_offset only when checksum type is not BLK_INTEGRITY_CSUM_NONE
  fs: add ioctl to query metadata and protection info capabilities

 block/bio-integrity-auto.c        |  4 +--
 block/blk-integrity.c             | 54 ++++++++++++++++++++++++++++++-
 block/blk-settings.c              | 44 +++++++++++++++++++++++--
 block/ioctl.c                     |  4 +++
 block/t10-pi.c                    | 16 ++++-----
 drivers/md/dm-crypt.c             |  4 +--
 drivers/md/dm-integrity.c         | 12 +++----
 drivers/nvdimm/btt.c              |  2 +-
 drivers/nvme/host/core.c          |  7 ++--
 drivers/nvme/target/io-cmd-bdev.c |  2 +-
 drivers/scsi/sd_dif.c             |  3 +-
 include/linux/blk-integrity.h     | 11 +++++--
 include/linux/blkdev.h            |  3 +-
 include/uapi/linux/fs.h           | 45 ++++++++++++++++++++++++++
 14 files changed, 181 insertions(+), 30 deletions(-)

-- 
2.25.1

[PATCH for-next v4 1/4] block: rename tuple_size field in blk_integrity to metadata_size

[Anuj Gupta]

The tuple_size field in blk_integrity currently represents the total
size of metadata associated with each data interval. To make the meaning
more explicit, rename tuple_size to metadata_size. This is a purely
mechanical rename with no functional changes.

Suggested-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
---
 block/bio-integrity-auto.c        |  4 ++--
 block/blk-integrity.c             |  2 +-
 block/blk-settings.c              |  6 +++---
 block/t10-pi.c                    | 16 ++++++++--------
 drivers/md/dm-crypt.c             |  4 ++--
 drivers/md/dm-integrity.c         | 12 ++++++------
 drivers/nvdimm/btt.c              |  2 +-
 drivers/nvme/host/core.c          |  2 +-
 drivers/nvme/target/io-cmd-bdev.c |  2 +-
 drivers/scsi/sd_dif.c             |  2 +-
 include/linux/blk-integrity.h     |  4 ++--
 include/linux/blkdev.h            |  2 +-
 12 files changed, 29 insertions(+), 29 deletions(-)

diff --git a/block/bio-integrity-auto.c b/block/bio-integrity-auto.c
index 9c6657664792..687952f63bbb 100644
--- a/block/bio-integrity-auto.c
+++ b/block/bio-integrity-auto.c
@@ -54,10 +54,10 @@ static bool bi_offload_capable(struct blk_integrity *bi)
 {
 	switch (bi->csum_type) {
 	case BLK_INTEGRITY_CSUM_CRC64:
-		return bi->tuple_size == sizeof(struct crc64_pi_tuple);
+		return bi->metadata_size == sizeof(struct crc64_pi_tuple);
 	case BLK_INTEGRITY_CSUM_CRC:
 	case BLK_INTEGRITY_CSUM_IP:
-		return bi->tuple_size == sizeof(struct t10_pi_tuple);
+		return bi->metadata_size == sizeof(struct t10_pi_tuple);
 	default:
 		pr_warn_once("%s: unknown integrity checksum type:%d\n",
 			__func__, bi->csum_type);
diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index e4e2567061f9..c1102bf4cd8d 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -239,7 +239,7 @@ static ssize_t format_show(struct device *dev, struct device_attribute *attr,
 {
 	struct blk_integrity *bi = dev_to_bi(dev);
 
-	if (!bi->tuple_size)
+	if (!bi->metadata_size)
 		return sysfs_emit(page, "none\n");
 	return sysfs_emit(page, "%s\n", blk_integrity_profile_name(bi));
 }
diff --git a/block/blk-settings.c b/block/blk-settings.c
index a000daafbfb4..787500ff00c3 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -114,7 +114,7 @@ static int blk_validate_integrity_limits(struct queue_limits *lim)
 {
 	struct blk_integrity *bi = &lim->integrity;
 
-	if (!bi->tuple_size) {
+	if (!bi->metadata_size) {
 		if (bi->csum_type != BLK_INTEGRITY_CSUM_NONE ||
 		    bi->tag_size || ((bi->flags & BLK_INTEGRITY_REF_TAG))) {
 			pr_warn("invalid PI settings.\n");
@@ -875,7 +875,7 @@ bool queue_limits_stack_integrity(struct queue_limits *t,
 		return true;
 
 	if (ti->flags & BLK_INTEGRITY_STACKED) {
-		if (ti->tuple_size != bi->tuple_size)
+		if (ti->metadata_size != bi->metadata_size)
 			goto incompatible;
 		if (ti->interval_exp != bi->interval_exp)
 			goto incompatible;
@@ -891,7 +891,7 @@ bool queue_limits_stack_integrity(struct queue_limits *t,
 		ti->flags |= (bi->flags & BLK_INTEGRITY_DEVICE_CAPABLE) |
 			     (bi->flags & BLK_INTEGRITY_REF_TAG);
 		ti->csum_type = bi->csum_type;
-		ti->tuple_size = bi->tuple_size;
+		ti->metadata_size = bi->metadata_size;
 		ti->pi_offset = bi->pi_offset;
 		ti->interval_exp = bi->interval_exp;
 		ti->tag_size = bi->tag_size;
diff --git a/block/t10-pi.c b/block/t10-pi.c
index 851db518ee5e..0c4ed9702146 100644
--- a/block/t10-pi.c
+++ b/block/t10-pi.c
@@ -56,7 +56,7 @@ static void t10_pi_generate(struct blk_integrity_iter *iter,
 			pi->ref_tag = 0;
 
 		iter->data_buf += iter->interval;
-		iter->prot_buf += bi->tuple_size;
+		iter->prot_buf += bi->metadata_size;
 		iter->seed++;
 	}
 }
@@ -105,7 +105,7 @@ static blk_status_t t10_pi_verify(struct blk_integrity_iter *iter,
 
 next:
 		iter->data_buf += iter->interval;
-		iter->prot_buf += bi->tuple_size;
+		iter->prot_buf += bi->metadata_size;
 		iter->seed++;
 	}
 
@@ -125,7 +125,7 @@ static blk_status_t t10_pi_verify(struct blk_integrity_iter *iter,
 static void t10_pi_type1_prepare(struct request *rq)
 {
 	struct blk_integrity *bi = &rq->q->limits.integrity;
-	const int tuple_sz = bi->tuple_size;
+	const int tuple_sz = bi->metadata_size;
 	u32 ref_tag = t10_pi_ref_tag(rq);
 	u8 offset = bi->pi_offset;
 	struct bio *bio;
@@ -177,7 +177,7 @@ static void t10_pi_type1_complete(struct request *rq, unsigned int nr_bytes)
 {
 	struct blk_integrity *bi = &rq->q->limits.integrity;
 	unsigned intervals = nr_bytes >> bi->interval_exp;
-	const int tuple_sz = bi->tuple_size;
+	const int tuple_sz = bi->metadata_size;
 	u32 ref_tag = t10_pi_ref_tag(rq);
 	u8 offset = bi->pi_offset;
 	struct bio *bio;
@@ -234,7 +234,7 @@ static void ext_pi_crc64_generate(struct blk_integrity_iter *iter,
 			put_unaligned_be48(0ULL, pi->ref_tag);
 
 		iter->data_buf += iter->interval;
-		iter->prot_buf += bi->tuple_size;
+		iter->prot_buf += bi->metadata_size;
 		iter->seed++;
 	}
 }
@@ -289,7 +289,7 @@ static blk_status_t ext_pi_crc64_verify(struct blk_integrity_iter *iter,
 
 next:
 		iter->data_buf += iter->interval;
-		iter->prot_buf += bi->tuple_size;
+		iter->prot_buf += bi->metadata_size;
 		iter->seed++;
 	}
 
@@ -299,7 +299,7 @@ static blk_status_t ext_pi_crc64_verify(struct blk_integrity_iter *iter,
 static void ext_pi_type1_prepare(struct request *rq)
 {
 	struct blk_integrity *bi = &rq->q->limits.integrity;
-	const int tuple_sz = bi->tuple_size;
+	const int tuple_sz = bi->metadata_size;
 	u64 ref_tag = ext_pi_ref_tag(rq);
 	u8 offset = bi->pi_offset;
 	struct bio *bio;
@@ -340,7 +340,7 @@ static void ext_pi_type1_complete(struct request *rq, unsigned int nr_bytes)
 {
 	struct blk_integrity *bi = &rq->q->limits.integrity;
 	unsigned intervals = nr_bytes >> bi->interval_exp;
-	const int tuple_sz = bi->tuple_size;
+	const int tuple_sz = bi->metadata_size;
 	u64 ref_tag = ext_pi_ref_tag(rq);
 	u8 offset = bi->pi_offset;
 	struct bio *bio;
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 9dfdb63220d7..3d6d06b94c9f 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1189,11 +1189,11 @@ static int crypt_integrity_ctr(struct crypt_config *cc, struct dm_target *ti)
 		return -EINVAL;
 	}
 
-	if (bi->tuple_size < cc->used_tag_size) {
+	if (bi->metadata_size < cc->used_tag_size) {
 		ti->error = "Integrity profile tag size mismatch.";
 		return -EINVAL;
 	}
-	cc->tuple_size = bi->tuple_size;
+	cc->tuple_size = bi->metadata_size;
 	if (1 << bi->interval_exp != cc->sector_size) {
 		ti->error = "Integrity profile sector size mismatch.";
 		return -EINVAL;
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 4395657fa583..efeee0a873c0 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -3906,8 +3906,8 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim
 		struct blk_integrity *bi = &limits->integrity;
 
 		memset(bi, 0, sizeof(*bi));
-		bi->tuple_size = ic->tag_size;
-		bi->tag_size = bi->tuple_size;
+		bi->metadata_size = ic->tag_size;
+		bi->tag_size = bi->metadata_size;
 		bi->interval_exp =
 			ic->sb->log2_sectors_per_block + SECTOR_SHIFT;
 	}
@@ -4746,18 +4746,18 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned int argc, char **argv
 			ti->error = "Integrity profile not supported";
 			goto bad;
 		}
-		/*printk("tag_size: %u, tuple_size: %u\n", bi->tag_size, bi->tuple_size);*/
-		if (bi->tuple_size < ic->tag_size) {
+		/*printk("tag_size: %u, metadata_size: %u\n", bi->tag_size, bi->metadata_size);*/
+		if (bi->metadata_size < ic->tag_size) {
 			r = -EINVAL;
 			ti->error = "The integrity profile is smaller than tag size";
 			goto bad;
 		}
-		if ((unsigned long)bi->tuple_size > PAGE_SIZE / 2) {
+		if ((unsigned long)bi->metadata_size > PAGE_SIZE / 2) {
 			r = -EINVAL;
 			ti->error = "Too big tuple size";
 			goto bad;
 		}
-		ic->tuple_size = bi->tuple_size;
+		ic->tuple_size = bi->metadata_size;
 		if (1 << bi->interval_exp != ic->sectors_per_block << SECTOR_SHIFT) {
 			r = -EINVAL;
 			ti->error = "Integrity profile sector size mismatch";
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 423dcd190906..2a1aa32e6693 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1506,7 +1506,7 @@ static int btt_blk_init(struct btt *btt)
 	int rc;
 
 	if (btt_meta_size(btt) && IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY)) {
-		lim.integrity.tuple_size = btt_meta_size(btt);
+		lim.integrity.metadata_size = btt_meta_size(btt);
 		lim.integrity.tag_size = btt_meta_size(btt);
 	}
 
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 92697f98c601..b027dda38e69 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1866,7 +1866,7 @@ static bool nvme_init_integrity(struct nvme_ns_head *head,
 		break;
 	}
 
-	bi->tuple_size = head->ms;
+	bi->metadata_size = head->ms;
 	bi->pi_offset = info->pi_offset;
 	return true;
 }
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index eba42df2f821..42fb19f94ab8 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -65,7 +65,7 @@ static void nvmet_bdev_ns_enable_integrity(struct nvmet_ns *ns)
 		return;
 
 	if (bi->csum_type == BLK_INTEGRITY_CSUM_CRC) {
-		ns->metadata_size = bi->tuple_size;
+		ns->metadata_size = bi->metadata_size;
 		if (bi->flags & BLK_INTEGRITY_REF_TAG)
 			ns->pi_type = NVME_NS_DPS_PI_TYPE1;
 		else
diff --git a/drivers/scsi/sd_dif.c b/drivers/scsi/sd_dif.c
index ae6ce6f5d622..18bfca1f1c78 100644
--- a/drivers/scsi/sd_dif.c
+++ b/drivers/scsi/sd_dif.c
@@ -52,7 +52,7 @@ void sd_dif_config_host(struct scsi_disk *sdkp, struct queue_limits *lim)
 	if (type != T10_PI_TYPE3_PROTECTION)
 		bi->flags |= BLK_INTEGRITY_REF_TAG;
 
-	bi->tuple_size = sizeof(struct t10_pi_tuple);
+	bi->metadata_size = sizeof(struct t10_pi_tuple);
 
 	if (dif && type) {
 		bi->flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
diff --git a/include/linux/blk-integrity.h b/include/linux/blk-integrity.h
index c7eae0bfb013..d27730da47f3 100644
--- a/include/linux/blk-integrity.h
+++ b/include/linux/blk-integrity.h
@@ -33,7 +33,7 @@ int blk_rq_integrity_map_user(struct request *rq, void __user *ubuf,
 static inline bool
 blk_integrity_queue_supports_integrity(struct request_queue *q)
 {
-	return q->limits.integrity.tuple_size;
+	return q->limits.integrity.metadata_size;
 }
 
 static inline struct blk_integrity *blk_get_integrity(struct gendisk *disk)
@@ -74,7 +74,7 @@ static inline unsigned int bio_integrity_intervals(struct blk_integrity *bi,
 static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
 					       unsigned int sectors)
 {
-	return bio_integrity_intervals(bi, sectors) * bi->tuple_size;
+	return bio_integrity_intervals(bi, sectors) * bi->metadata_size;
 }
 
 static inline bool blk_integrity_rq(struct request *rq)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a59880c809c7..ccda87d06a38 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -116,7 +116,7 @@ enum blk_integrity_checksum {
 struct blk_integrity {
 	unsigned char				flags;
 	enum blk_integrity_checksum		csum_type;
-	unsigned char				tuple_size;
+	unsigned char				metadata_size;
 	unsigned char				pi_offset;
 	unsigned char				interval_exp;
 	unsigned char				tag_size;
-- 
2.25.1

Re: [PATCH for-next v4 1/4] block: rename tuple_size field in blk_integrity to metadata_size

[Christoph Hellwig]

On Wed, Jun 18, 2025 at 11:21:50AM +0530, Anuj Gupta wrote:
> @@ -299,7 +299,7 @@ static blk_status_t ext_pi_crc64_verify(struct blk_integrity_iter *iter,
>  static void ext_pi_type1_prepare(struct request *rq)
>  {
>  	struct blk_integrity *bi = &rq->q->limits.integrity;
> -	const int tuple_sz = bi->tuple_size;
> +	const int tuple_sz = bi->metadata_size;

I guess keeping tuple here is fine because we're deep into PI code.

The rest looks good as well:

Reviewed-by: Christoph Hellwig <hch@lst.de>

[PATCH for-next v4 2/4] block: introduce pi_tuple_size field in blk_integrity

[Anuj Gupta]

Introduce a new pi_tuple_size field in struct blk_integrity to
explicitly represent the size (in bytes) of the protection information
(PI) tuple. This is a prep patch.
Add validation in blk_validate_integrity_limits() to ensure that
pi size matches the expected size for known checksum types and never
exceeds the pi_tuple_size.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-settings.c     | 38 ++++++++++++++++++++++++++++++++++++++
 drivers/nvme/host/core.c |  2 ++
 drivers/scsi/sd_dif.c    |  1 +
 include/linux/blkdev.h   |  1 +
 4 files changed, 42 insertions(+)

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 787500ff00c3..32f3cdc9835a 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -14,6 +14,8 @@
 #include <linux/jiffies.h>
 #include <linux/gfp.h>
 #include <linux/dma-mapping.h>
+#include <linux/t10-pi.h>
+#include <linux/crc64.h>
 
 #include "blk.h"
 #include "blk-rq-qos.h"
@@ -135,6 +137,42 @@ static int blk_validate_integrity_limits(struct queue_limits *lim)
 		return -EINVAL;
 	}
 
+	if (bi->pi_tuple_size > bi->metadata_size) {
+		pr_warn("pi_tuple_size (%u) exceeds metadata_size (%u)\n",
+			 bi->pi_tuple_size,
+			 bi->metadata_size);
+		return -EINVAL;
+	}
+
+	switch (bi->csum_type) {
+	case BLK_INTEGRITY_CSUM_NONE:
+		if (bi->pi_tuple_size) {
+			pr_warn("pi_tuple_size must be 0 when checksum type \
+				 is none\n");
+			return -EINVAL;
+		}
+		break;
+	case BLK_INTEGRITY_CSUM_CRC:
+	case BLK_INTEGRITY_CSUM_IP:
+		if (bi->pi_tuple_size != sizeof(struct t10_pi_tuple)) {
+			pr_warn("pi_tuple_size mismatch for T10 PI: expected \
+				 %zu, got %u\n",
+				 sizeof(struct t10_pi_tuple),
+				 bi->pi_tuple_size);
+			return -EINVAL;
+		}
+		break;
+	case BLK_INTEGRITY_CSUM_CRC64:
+		if (bi->pi_tuple_size != sizeof(struct crc64_pi_tuple)) {
+			pr_warn("pi_tuple_size mismatch for CRC64 PI: \
+				 expected %zu, got %u\n",
+				 sizeof(struct crc64_pi_tuple),
+				 bi->pi_tuple_size);
+			return -EINVAL;
+		}
+		break;
+	}
+
 	if (!bi->interval_exp)
 		bi->interval_exp = ilog2(lim->logical_block_size);
 
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index b027dda38e69..fe72accab516 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1867,6 +1867,8 @@ static bool nvme_init_integrity(struct nvme_ns_head *head,
 	}
 
 	bi->metadata_size = head->ms;
+	if (bi->csum_type)
+		bi->pi_tuple_size = head->pi_size;
 	bi->pi_offset = info->pi_offset;
 	return true;
 }
diff --git a/drivers/scsi/sd_dif.c b/drivers/scsi/sd_dif.c
index 18bfca1f1c78..ff4217fef93b 100644
--- a/drivers/scsi/sd_dif.c
+++ b/drivers/scsi/sd_dif.c
@@ -53,6 +53,7 @@ void sd_dif_config_host(struct scsi_disk *sdkp, struct queue_limits *lim)
 		bi->flags |= BLK_INTEGRITY_REF_TAG;
 
 	bi->metadata_size = sizeof(struct t10_pi_tuple);
+	bi->pi_tuple_size = bi->metadata_size;
 
 	if (dif && type) {
 		bi->flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ccda87d06a38..0d4011dcfed3 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -120,6 +120,7 @@ struct blk_integrity {
 	unsigned char				pi_offset;
 	unsigned char				interval_exp;
 	unsigned char				tag_size;
+	unsigned char				pi_tuple_size;
 };
 
 typedef unsigned int __bitwise blk_mode_t;
-- 
2.25.1

[PATCH for-next v4 3/4] set pi_offset only when checksum type is not BLK_INTEGRITY_CSUM_NONE

[Anuj Gupta]

protection information is treated as opaque when checksum type is
BLK_INTEGRITY_CSUM_NONE. In order to maintain the right metadata
semantics, set pi_offset only in cases where checksum type is not
BLK_INTEGRITY_CSUM_NONE.

Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
---
 drivers/nvme/host/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fe72accab516..806b6e73276d 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1867,9 +1867,10 @@ static bool nvme_init_integrity(struct nvme_ns_head *head,
 	}
 
 	bi->metadata_size = head->ms;
-	if (bi->csum_type)
+	if (bi->csum_type) {
 		bi->pi_tuple_size = head->pi_size;
-	bi->pi_offset = info->pi_offset;
+		bi->pi_offset = info->pi_offset;
+	}
 	return true;
 }
 
-- 
2.25.1

Re: [PATCH for-next v4 3/4] set pi_offset only when checksum type is not BLK_INTEGRITY_CSUM_NONE

[Christoph Hellwig]

The Subject line is missing an "nvme: " prefix.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

[PATCH for-next v4 4/4] fs: add ioctl to query metadata and protection info capabilities

[Anuj Gupta]

Add a new ioctl, FS_IOC_GETLBMD_CAP, to query metadata and protection
info (PI) capabilities. This ioctl returns information about the files
integrity profile. This is useful for userspace applications to
understand a files end-to-end data protection support and configure the
I/O accordingly.

For now this interface is only supported by block devices. However the
design and placement of this ioctl in generic FS ioctl space allows us
to extend it to work over files as well. This maybe useful when
filesystems start supporting  PI-aware layouts.

A new structure struct logical_block_metadata_cap is introduced, which
contains the following fields:

1. lbmd_flags: bitmask of logical block metadata capability flags
2. lbmd_interval: the amount of data described by each unit of logical
block metadata
3. lbmd_size: size in bytes of the logical block metadata associated
with each interval
4. lbmd_opaque_size: size in bytes of the opaque block tag associated
with each interval
5. lbmd_opaque_offset: offset in bytes of the opaque block tag within
the logical block metadata
6. lbmd_pi_size: size in bytes of the T10 PI tuple associated with each
interval
7. lbmd_pi_offset: offset in bytes of T10 PI tuple within the logical
block metadata
8. lbmd_pi_guard_tag_type: T10 PI guard tag type
9. lbmd_pi_app_tag_size: size in bytes of the T10 PI application tag
10. lbmd_pi_ref_tag_size: size in bytes of the T10 PI reference tag
11. lbmd_pi_storage_tag_size: size in bytes of the T10 PI storage tag

The internal logic to fetch the capability is encapsulated in a helper
function blk_get_meta_cap(), which uses the blk_integrity profile
associated with the device. The ioctl returns -EOPNOTSUPP, if
CONFIG_BLK_DEV_INTEGRITY is not enabled.

Suggested-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
---
 block/blk-integrity.c         | 52 +++++++++++++++++++++++++++++++++++
 block/ioctl.c                 |  4 +++
 include/linux/blk-integrity.h |  7 +++++
 include/uapi/linux/fs.h       | 45 ++++++++++++++++++++++++++++++
 4 files changed, 108 insertions(+)

diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index c1102bf4cd8d..9d9dc9c32083 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -13,6 +13,7 @@
 #include <linux/scatterlist.h>
 #include <linux/export.h>
 #include <linux/slab.h>
+#include <linux/t10-pi.h>
 
 #include "blk.h"
 
@@ -54,6 +55,57 @@ int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
 	return segments;
 }
 
+int blk_get_meta_cap(struct block_device *bdev, unsigned int cmd,
+		     struct logical_block_metadata_cap __user *argp)
+{
+	struct blk_integrity *bi = blk_get_integrity(bdev->bd_disk);
+	struct logical_block_metadata_cap meta_cap = {};
+	size_t usize = _IOC_SIZE(cmd);
+
+	if (!argp)
+		return -EINVAL;
+	if (usize < LBMD_SIZE_VER0)
+		return -EINVAL;
+	if (!bi)
+		goto out;
+
+	if (bi->flags & BLK_INTEGRITY_DEVICE_CAPABLE)
+		meta_cap.lbmd_flags |= LBMD_PI_CAP_INTEGRITY;
+	if (bi->flags & BLK_INTEGRITY_REF_TAG)
+		meta_cap.lbmd_flags |= LBMD_PI_CAP_REFTAG;
+	meta_cap.lbmd_interval = 1 << bi->interval_exp;
+	meta_cap.lbmd_size = bi->metadata_size;
+	meta_cap.lbmd_pi_size = bi->pi_tuple_size;
+	meta_cap.lbmd_pi_offset = bi->pi_offset;
+	meta_cap.lbmd_opaque_size = bi->metadata_size - bi->pi_tuple_size;
+	if (meta_cap.lbmd_opaque_size && !bi->pi_offset)
+		meta_cap.lbmd_opaque_offset = bi->pi_tuple_size;
+
+	meta_cap.lbmd_guard_tag_type = bi->csum_type;
+	if (bi->csum_type != BLK_INTEGRITY_CSUM_NONE)
+		meta_cap.lbmd_app_tag_size = 2;
+
+	if (bi->flags & BLK_INTEGRITY_REF_TAG) {
+		switch (bi->csum_type) {
+		case BLK_INTEGRITY_CSUM_CRC64:
+			meta_cap.lbmd_ref_tag_size =
+				sizeof_field(struct crc64_pi_tuple, ref_tag);
+			break;
+		case BLK_INTEGRITY_CSUM_CRC:
+		case BLK_INTEGRITY_CSUM_IP:
+			meta_cap.lbmd_ref_tag_size =
+				sizeof_field(struct t10_pi_tuple, ref_tag);
+			break;
+		default:
+			break;
+		}
+	}
+
+out:
+	return copy_struct_to_user(argp, usize, &meta_cap, sizeof(meta_cap),
+				   NULL);
+}
+
 /**
  * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
  * @rq:		request to map
diff --git a/block/ioctl.c b/block/ioctl.c
index e472cc1030c6..9ad403733e19 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -13,6 +13,7 @@
 #include <linux/uaccess.h>
 #include <linux/pagemap.h>
 #include <linux/io_uring/cmd.h>
+#include <linux/blk-integrity.h>
 #include <uapi/linux/blkdev.h>
 #include "blk.h"
 #include "blk-crypto-internal.h"
@@ -566,6 +567,9 @@ static int blkdev_common_ioctl(struct block_device *bdev, blk_mode_t mode,
 {
 	unsigned int max_sectors;
 
+	if (_IOC_NR(cmd) == _IOC_NR(FS_IOC_GETLBMD_CAP))
+		return blk_get_meta_cap(bdev, cmd, argp);
+
 	switch (cmd) {
 	case BLKFLSBUF:
 		return blkdev_flushbuf(bdev, cmd, arg);
diff --git a/include/linux/blk-integrity.h b/include/linux/blk-integrity.h
index d27730da47f3..e04c6e5bf1c6 100644
--- a/include/linux/blk-integrity.h
+++ b/include/linux/blk-integrity.h
@@ -29,6 +29,8 @@ int blk_rq_map_integrity_sg(struct request *, struct scatterlist *);
 int blk_rq_count_integrity_sg(struct request_queue *, struct bio *);
 int blk_rq_integrity_map_user(struct request *rq, void __user *ubuf,
 			      ssize_t bytes);
+int blk_get_meta_cap(struct block_device *bdev, unsigned int cmd,
+		     struct logical_block_metadata_cap __user *argp);
 
 static inline bool
 blk_integrity_queue_supports_integrity(struct request_queue *q)
@@ -92,6 +94,11 @@ static inline struct bio_vec rq_integrity_vec(struct request *rq)
 				 rq->bio->bi_integrity->bip_iter);
 }
 #else /* CONFIG_BLK_DEV_INTEGRITY */
+static inline int blk_get_meta_cap(struct block_device *bdev, unsigned int cmd,
+				   struct logical_block_metadata_cap __user *argp)
+{
+	return -EOPNOTSUPP;
+}
 static inline int blk_rq_count_integrity_sg(struct request_queue *q,
 					    struct bio *b)
 {
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 0098b0ce8ccb..267efbc17d48 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -91,6 +91,49 @@ struct fs_sysfs_path {
 	__u8			name[128];
 };
 
+/* Protection info capability flags */
+#define	LBMD_PI_CAP_INTEGRITY		(1 << 0)
+#define	LBMD_PI_CAP_REFTAG		(1 << 1)
+
+/* Checksum types for Protection Information */
+#define LBMD_PI_CSUM_NONE		0
+#define LBMD_PI_CSUM_IP			1
+#define LBMD_PI_CSUM_CRC16_T10DIF	2
+#define LBMD_PI_CSUM_CRC64_NVME		4
+
+/* sizeof first published struct */
+#define LBMD_SIZE_VER0			16
+
+/*
+ * struct logical_block_metadata_cap - Logical block metadata capability
+ * If the device does not support metadata, all the fields will be zero.
+ * Applications must check lbmd_flags to determine whether metadata is supported or not.
+ */
+struct logical_block_metadata_cap {
+	/* Bitmask of logical block metadata capability flags */
+	__u32	lbmd_flags;
+	/* The amount of data described by each unit of logical block metadata */
+	__u16	lbmd_interval;
+	/* Size in bytes of the logical block metadata associated with each interval */
+	__u8	lbmd_size;
+	/* Size in bytes of the opaque block tag associated with each interval */
+	__u8	lbmd_opaque_size;
+	/* Offset in bytes of the opaque block tag within the logical block metadata */
+	__u8	lbmd_opaque_offset;
+	/* Size in bytes of the T10 PI tuple associated with each interval */
+	__u8	lbmd_pi_size;
+	/* Offset in bytes of T10 PI tuple within the logical block metadata */
+	__u8	lbmd_pi_offset;
+	/* T10 PI guard tag type */
+	__u8	lbmd_guard_tag_type;
+	/* Size in bytes of the T10 PI application tag */
+	__u8	lbmd_app_tag_size;
+	/* Size in bytes of the T10 PI reference tag */
+	__u8	lbmd_ref_tag_size;
+	/* Size in bytes of the T10 PI storage tag */
+	__u8	lbmd_storage_tag_size;
+};
+
 /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */
 #define FILE_DEDUPE_RANGE_SAME		0
 #define FILE_DEDUPE_RANGE_DIFFERS	1
@@ -247,6 +290,8 @@ struct fsxattr {
  * also /sys/kernel/debug/ for filesystems with debugfs exports
  */
 #define FS_IOC_GETFSSYSFSPATH		_IOR(0x15, 1, struct fs_sysfs_path)
+/* Get logical block metadata capability details */
+#define FS_IOC_GETLBMD_CAP		_IOWR(0x15, 2, struct logical_block_metadata_cap)
 
 /*
  * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)
-- 
2.25.1

Re: [PATCH for-next v4 4/4] fs: add ioctl to query metadata and protection info capabilities

[Christoph Hellwig]

On Wed, Jun 18, 2025 at 11:21:53AM +0530, Anuj Gupta wrote:
> +/*
> + * struct logical_block_metadata_cap - Logical block metadata capability

No real need to duplicate the struct name here.

> + * If the device does not support metadata, all the fields will be zero.
> + * Applications must check lbmd_flags to determine whether metadata is supported or not.

Overly long line.

> + */
> +struct logical_block_metadata_cap {
> +	/* Bitmask of logical block metadata capability flags */
> +	__u32	lbmd_flags;
> +	/* The amount of data described by each unit of logical block metadata */

Loit sof overly long lines, please reformat these as block comments.

> +	__u16	lbmd_interval;
> +	/* Size in bytes of the logical block metadata associated with each interval */
> +	__u8	lbmd_size;
> +	/* Size in bytes of the opaque block tag associated with each interval */
> +	__u8	lbmd_opaque_size;



> +	/* Offset in bytes of the opaque block tag within the logical block metadata */
>
> +	__u8	lbmd_opaque_offset;
> +	/* Size in bytes of the T10 PI tuple associated with each interval */
> +	__u8	lbmd_pi_size;
> +	/* Offset in bytes of T10 PI tuple within the logical block metadata */
> +	__u8	lbmd_pi_offset;
> +	/* T10 PI guard tag type */
> +	__u8	lbmd_guard_tag_type;
> +	/* Size in bytes of the T10 PI application tag */
> +	__u8	lbmd_app_tag_size;
> +	/* Size in bytes of the T10 PI reference tag */
> +	__u8	lbmd_ref_tag_size;
> +	/* Size in bytes of the T10 PI storage tag */
> +	__u8	lbmd_storage_tag_size;
> +};

This leaves a byte of padding at the end, leaving to issues with
compiler alignments and potentially leaking uninitialized stack data.

Re: [PATCH for-next v4 0/4] add ioctl to query metadata and protection info capabilities

[Martin K. Petersen]

Anuj,

> This patch series adds a new ioctl to query metadata and integrity
> capability.
>
> Patch 1 renames tuple_size field to metadata_size
> Patch_2 adds a pi_tuple_size field in blk_integrity struct which is later
> used to export this value to the user as well.
> Patch 3 allows computing right pi_offset value.
> Patch 4 introduces a new ioctl to query integrity capability.

This looks good to me. Thanks for making all the changes!

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen