[SCSI] sd: Correctly handle all combinations of DIF and DIX

The old detection code couldn't handle all possible combinations of
DIX and DIF.  This version does, giving priority to DIX if the
controller is capable.

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

3 files changed, 23 insertions, 19 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a494a2e..7c4d2e6 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -575,7 +575,8 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq)
 
 	/* If DIF or DIX is enabled, tell HBA how to handle request */
 	if (host_dif || scsi_prot_sg_count(SCpnt))
-		sd_dif_op(SCpnt, sdkp->protection_type, scsi_prot_sg_count(SCpnt));
+		sd_dif_op(SCpnt, host_dif, scsi_prot_sg_count(SCpnt),
+			  sdkp->protection_type);
 
 	/*
 	 * We shouldn't disconnect in the middle of a sector, so with a dumb
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 95b9f06..a92b991 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -99,7 +99,7 @@ struct sd_dif_tuple {
 
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 
-extern void sd_dif_op(struct scsi_cmnd *, unsigned int, unsigned int);
+extern void sd_dif_op(struct scsi_cmnd *, unsigned int, unsigned int, unsigned int);
 extern void sd_dif_config_host(struct scsi_disk *);
 extern int sd_dif_prepare(struct request *rq, sector_t, unsigned int);
 extern void sd_dif_complete(struct scsi_cmnd *, unsigned int);
diff --git a/drivers/scsi/sd_dif.c b/drivers/scsi/sd_dif.c
index 943fde7..194c770 100644
--- a/drivers/scsi/sd_dif.c
+++ b/drivers/scsi/sd_dif.c
@@ -311,24 +311,26 @@ void sd_dif_config_host(struct scsi_disk *sdkp)
 	struct scsi_device *sdp = sdkp->device;
 	struct gendisk *disk = sdkp->disk;
 	u8 type = sdkp->protection_type;
+	int dif, dix;
 
-	/* If this HBA doesn't support DIX, resort to normal I/O or DIF */
-	if (scsi_host_dix_capable(sdp->host, type) == 0) {
+	dif = scsi_host_dif_capable(sdp->host, type);
+	dix = scsi_host_dix_capable(sdp->host, type);
 
-		if (type == SD_DIF_TYPE0_PROTECTION)
-			return;
-
-		if (scsi_host_dif_capable(sdp->host, type) == 0) {
-			sd_printk(KERN_INFO, sdkp, "Type %d protection " \
-				  "unsupported by HBA. Disabling DIF.\n", type);
-			return;
-		}
+	if (!dix && scsi_host_dix_capable(sdp->host, 0)) {
+		dif = 0; dix = 1;
+	}
 
-		sd_printk(KERN_INFO, sdkp, "Enabling DIF Type %d protection\n",
-			  type);
+	if (type) {
+		if (dif)
+			sd_printk(KERN_INFO, sdkp,
+				  "Enabling DIF Type %d protection\n", type);
+		else
+			sd_printk(KERN_INFO, sdkp,
+				  "Disabling DIF Type %d protection\n", type);
+	}
 
+	if (!dix)
 		return;
-	}
 
 	/* Enable DMA of protection information */
 	if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP)
@@ -343,10 +345,10 @@ void sd_dif_config_host(struct scsi_disk *sdkp)
 			blk_integrity_register(disk, &dif_type1_integrity_crc);
 
 	sd_printk(KERN_INFO, sdkp,
-		  "Enabling %s integrity protection\n", disk->integrity->name);
+		  "Enabling DIX %s protection\n", disk->integrity->name);
 
 	/* Signal to block layer that we support sector tagging */
-	if (type && sdkp->ATO) {
+	if (dif && type && sdkp->ATO) {
 		if (type == SD_DIF_TYPE3_PROTECTION)
 			disk->integrity->tag_size = sizeof(u16) + sizeof(u32);
 		else
@@ -360,7 +362,7 @@ void sd_dif_config_host(struct scsi_disk *sdkp)
 /*
  * DIF DMA operation magic decoder ring.
  */
-void sd_dif_op(struct scsi_cmnd *scmd, unsigned int dif, unsigned int dix)
+void sd_dif_op(struct scsi_cmnd *scmd, unsigned int dif, unsigned int dix, unsigned int type)
 {
 	int csum_convert, prot_op;
 
@@ -405,7 +407,8 @@ void sd_dif_op(struct scsi_cmnd *scmd, unsigned int dif, unsigned int dix)
 	}
 
 	scsi_set_prot_op(scmd, prot_op);
-	scsi_set_prot_type(scmd, dif);
+	if (dif)
+		scsi_set_prot_type(scmd, type);
 }
 
 /*