[SCSI] Support devices with protection information

Implement support for DMA of protection information for devices that
are data integrity capable.

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

 - Allocate protection scsi_data_buffer if host is DIX (integrity DMA)
   capable.

 - Accessor function for checking whether a device has protection
   enabled.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 402c1078d01c..f9f6e793575c 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -90,6 +90,8 @@ 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 */
 
@@ -274,4 +276,22 @@ static inline sector_t scsi_get_lba(struct scsi_cmnd *scmd)
         return scmd->request->sector;
 }
 
+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 */