[PATCH] nvme-fc: add DIF support for intergrity metadata

[Atharva Tiwari <evepolonium@gmail.com>]

This patch enhances the NVMe over Fibre Channel (NVMe-FC) driver to 
handle requests with integrity metadata (DIF).

- Added the inclusion of `<linux/blk-integrity.h>` to enable integrity operations.
- Implemented support for mapping integrity metadata using `blk_rq_map_integrity_sg`.
- Ensures proper handling of requests with integrity metadata, including error cases where mapping fails.

This update improves the reliability of data integrity checks in environments utilizing DIF.

Signed-off-by: Atharva Tiwari <evepolonium@gmail.com>
---
 drivers/nvme/host/fc.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index b81af7919e94..d0343133413f 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -17,6 +17,7 @@
 #include "fc.h"
 #include <scsi/scsi_transport_fc.h>
 #include <linux/blk-mq-pci.h>
+#include <linux/blk-integrity.h>
 
 /* *************************** Data Structures/Defines ****************** */
 
@@ -2620,10 +2621,16 @@ nvme_fc_map_data(struct nvme_fc_ctrl *ctrl, struct request *rq,
 		freq->sg_cnt = 0;
 		return -EFAULT;
 	}
-
-	/*
-	 * TODO: blk_integrity_rq(rq)  for DIF
-	 */
+	/* Handle requests with integrity metadata (DIF) */
+	if (blk_integrity_rq(rq)) {
+		ret = blk_rq_map_integrity_sg(rq, freq->sg_table.sgl);
+		if (ret < 0) {
+			sg_free_table_chained(&freq->sg_table, NVME_INLINE_SG_CNT);
+			freq->sg_cnt = 0;
+			return -EFAULT;
+		}
+		freq->sg_cnt += ret;
+	}
 	return 0;
 }
 
-- 
2.39.5