[PATCH for-next v3 1/2] block: introduce pi_size field in blk_integrity

[Anuj Gupta <anuj20.g@xxxxxxxxxxx>]

Introduce a new pi_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 know checksum types and never
exceeds the tuple_size.

Suggested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
---
 block/blk-settings.c     | 37 +++++++++++++++++++++++++++++++++++++
 drivers/nvme/host/core.c |  1 +
 drivers/scsi/sd_dif.c    |  1 +
 include/linux/blkdev.h   |  1 +
 4 files changed, 40 insertions(+)

diff --git a/block/blk-settings.c b/block/blk-settings.c
index a000daafbfb4..125b23acb5b7 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 +137,41 @@ static int blk_validate_integrity_limits(struct queue_limits *lim)
 		return -EINVAL;
 	}
 
+	if (bi->pi_size > bi->tuple_size) {
+		pr_warn("pi_size (%u) exceeds tuple_size (%u)\n",
+						bi->pi_size, bi->tuple_size);
+		return -EINVAL;
+	}
+
+	switch (bi->csum_type) {
+	case BLK_INTEGRITY_CSUM_NONE:
+		if (!bi->pi_size) {
+			pr_warn("pi_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_size != sizeof(struct t10_pi_tuple)) {
+			pr_warn("pi_size mismatch for T10 PI: expected \
+				 %zu, got %u\n",
+				 sizeof(struct t10_pi_tuple),
+				 bi->pi_size);
+			return -EINVAL;
+		}
+		break;
+	case BLK_INTEGRITY_CSUM_CRC64:
+		if (bi->pi_size != sizeof(struct crc64_pi_tuple)) {
+			pr_warn("pi_size mismatch for CRC64 PI: \
+				 expected %zu, got %u\n",
+				 sizeof(struct crc64_pi_tuple),
+				 bi->pi_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 f69a232a000a..a9a2a0ca9797 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1868,6 +1868,7 @@ static bool nvme_init_integrity(struct nvme_ns_head *head,
 	}
 
 	bi->tuple_size = head->ms;
+	bi->pi_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 ae6ce6f5d622..9c39a82298da 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->tuple_size = sizeof(struct t10_pi_tuple);
+	bi->pi_size = bi->tuple_size;
 
 	if (dif && type) {
 		bi->flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 332b56f323d9..1ed604b70e0f 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_size;
 };
 
 typedef unsigned int __bitwise blk_mode_t;
-- 
2.25.1