[PATCH v3] block: fix lbmd_guard_tag_type assignment in FS_IOC_GETLBMD_CAP

[Anuj Gupta <anuj20.g@samsung.com>]

The blk_get_meta_cap() implementation directly assigns bi->csum_type to
the UAPI field lbmd_guard_tag_type. This is not right as the kernel enum
blk_integrity_checksum values are not guaranteed to match the UAPI
defined values.

Fix this by explicitly mapping internal checksum types to UAPI-defined
constants to ensure compatibility and correctness, especially for the
devices using CRC64 PI.

Fixes: 9eb22f7fedfc ("fs: add ioctl to query metadata and protection info capabilities")
Reported-by: Vincent Fu <vincent.fu@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-integrity.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index 61a79e19c78f..056b8948369d 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -83,7 +83,21 @@ int blk_get_meta_cap(struct block_device *bdev, unsigned int cmd,
 	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;
+	switch (bi->csum_type) {
+	case BLK_INTEGRITY_CSUM_NONE:
+		meta_cap.lbmd_guard_tag_type = LBMD_PI_CSUM_NONE;
+		break;
+	case BLK_INTEGRITY_CSUM_IP:
+		meta_cap.lbmd_guard_tag_type = LBMD_PI_CSUM_IP;
+		break;
+	case BLK_INTEGRITY_CSUM_CRC:
+		meta_cap.lbmd_guard_tag_type = LBMD_PI_CSUM_CRC16_T10DIF;
+		break;
+	case BLK_INTEGRITY_CSUM_CRC64:
+		meta_cap.lbmd_guard_tag_type = LBMD_PI_CSUM_CRC64_NVME;
+		break;
+	}
+
 	if (bi->csum_type != BLK_INTEGRITY_CSUM_NONE)
 		meta_cap.lbmd_app_tag_size = 2;
 
-- 
2.25.1