[PATCH 04 of 10] scsi: Support devices with protection information (DIF)

["Martin K. Petersen" <martin.petersen@xxxxxxxxxx>]

 - Add support for an extra scatter-gather list containing protection
   information.

 - Remember devices with protection information turned on in INQUIRY.

Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>

---
4 files changed, 62 insertions(+)
drivers/scsi/scsi_lib.c    |   38 ++++++++++++++++++++++++++++++++++++++
drivers/scsi/scsi_scan.c   |    3 +++
include/scsi/scsi_cmnd.h   |   20 ++++++++++++++++++++
include/scsi/scsi_device.h |    1 +



diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -778,6 +778,11 @@ void scsi_release_buffers(struct scsi_cm
 		kmem_cache_free(scsi_sdb_cache, bidi_sdb);
 		cmd->request->next_rq->special = NULL;
 	}
+
+	if (scsi_prot_sg_count(cmd)) {
+		scsi_free_sgtable(cmd->prot_sdb);
+		kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
+	}
 }
 EXPORT_SYMBOL(scsi_release_buffers);
 
@@ -1031,6 +1036,32 @@ static int scsi_init_sgtable(struct requ
 	return BLKPREP_OK;
 }
 
+static int scsi_protect_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
+{
+	struct request *req;
+	struct scsi_data_buffer *pdb;
+	int ivecs, count;
+
+	req = cmd->request;
+
+	pdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
+	if (unlikely(pdb == NULL))
+		return BLKPREP_DEFER;
+
+	ivecs = blk_rq_count_integrity_sg(req);
+
+	if (unlikely(scsi_alloc_sgtable(pdb, ivecs, gfp_mask)))
+		return BLKPREP_DEFER;
+
+	count = blk_rq_map_integrity_sg(req, pdb->table.sgl);
+	BUG_ON(unlikely(count > ivecs));
+
+	cmd->prot_sdb = pdb;
+	cmd->prot_sdb->table.nents = count;
+
+	return BLKPREP_OK;
+}
+
 /*
  * Function:    scsi_init_io()
  *
@@ -1060,6 +1091,13 @@ int scsi_init_io(struct scsi_cmnd *cmd, 
 		error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb,
 								    GFP_ATOMIC);
 		if (error)
+			goto err_exit;
+	}
+
+	if (blk_integrity_rq(cmd->request)) {
+		error = scsi_protect_io(cmd, gfp_mask);
+
+		if (error != BLKPREP_OK)
 			goto err_exit;
 	}
 
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -882,6 +882,9 @@ static int scsi_add_lun(struct scsi_devi
 
 	if (*bflags & BLIST_USE_10_BYTE_MS)
 		sdev->use_10_for_ms = 1;
+
+	if (inq_result[5] & 0x1)
+		sdev->protection = 1;
 
 	/* set the device running here so that slave configure
 	 * may do I/O */
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -88,6 +88,8 @@ struct scsi_cmnd {
 
 	/* These elements define the operation we ultimately want to perform */
 	struct scsi_data_buffer sdb;
+	struct scsi_data_buffer *prot_sdb;
+
 	unsigned underflow;	/* Return error if less than
 				   this amount is transferred */
 
@@ -209,4 +211,22 @@ static inline int scsi_sg_copy_to_buffer
 				 buf, buflen);
 }
 
+static inline unsigned scsi_prot_sg_count(struct scsi_cmnd *cmd)
+{
+	return cmd->prot_sdb ? cmd->prot_sdb->table.nents : 0;
+}
+
+static inline struct scatterlist *scsi_prot_sglist(struct scsi_cmnd *cmd)
+{
+	return cmd->prot_sdb ? cmd->prot_sdb->table.sgl : NULL;
+}
+
+static inline struct scsi_data_buffer *scsi_prot(struct scsi_cmnd *cmd)
+{
+	return cmd->prot_sdb;
+}
+
+#define scsi_for_each_prot_sg(cmd, sg, nseg, __i)		\
+	for_each_sg(scsi_prot_sglist(cmd), sg, nseg, __i)
+
 #endif /* _SCSI_SCSI_CMND_H */
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -140,6 +140,7 @@ struct scsi_device {
 	unsigned guess_capacity:1;	/* READ_CAPACITY might be too high by 1 */
 	unsigned retry_hwerror:1;	/* Retry HARDWARE_ERROR */
 	unsigned last_sector_bug:1;	/* Always read last sector in a 1 sector read */
+	unsigned protection:1;		/* Data Integrity Field */
 
 	DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
 	struct list_head event_list;	/* asserted events */


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