[SCSI] Add detailed SCSI I/O errors

Instead of just passing 'EIO' for any I/O error we should be
notifying the upper layers with more details about the cause
of this error.

Update the possible I/O errors to:

- ENOLINK: Link failure between host and target
- EIO: Retryable I/O error
- EREMOTEIO: Non-retryable I/O error
- EBADE: I/O error restricted to the I_T_L nexus

'Retryable' in this context means that an I/O error _might_ be
restricted to the I_T_L nexus (vulgo: path), so retrying on another
nexus / path might succeed.

'Non-retryable' in general refers to a target failure, so this
error will always be generated regardless of the I_T_L nexus
it was send on.

I/O errors restricted to the I_T_L nexus might be retried
on another nexus / path, but they should _not_ be queued
if no paths are available.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 17 insertions, 7 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 45c75649b9e0..991de3c15cfc 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -223,7 +223,7 @@ static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
  * @scmd:	Cmd to have sense checked.
  *
  * Return value:
- * 	SUCCESS or FAILED or NEEDS_RETRY
+ *	SUCCESS or FAILED or NEEDS_RETRY or TARGET_ERROR
  *
  * Notes:
  *	When a deferred error is detected the current command has
@@ -326,17 +326,19 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
 		 */
 		return SUCCESS;
 
-		/* these three are not supported */
+		/* these are not supported */
 	case COPY_ABORTED:
 	case VOLUME_OVERFLOW:
 	case MISCOMPARE:
-		return SUCCESS;
+	case BLANK_CHECK:
+	case DATA_PROTECT:
+		return TARGET_ERROR;
 
 	case MEDIUM_ERROR:
 		if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
 		    sshdr.asc == 0x13 || /* AMNF DATA FIELD */
 		    sshdr.asc == 0x14) { /* RECORD NOT FOUND */
-			return SUCCESS;
+			return TARGET_ERROR;
 		}
 		return NEEDS_RETRY;
 
@@ -344,11 +346,9 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
 		if (scmd->device->retry_hwerror)
 			return ADD_TO_MLQUEUE;
 		else
-			return SUCCESS;
+			return TARGET_ERROR;
 
 	case ILLEGAL_REQUEST:
-	case BLANK_CHECK:
-	case DATA_PROTECT:
 	default:
 		return SUCCESS;
 	}
@@ -787,6 +787,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 		case SUCCESS:
 		case NEEDS_RETRY:
 		case FAILED:
+		case TARGET_ERROR:
 			break;
 		case ADD_TO_MLQUEUE:
 			rtn = NEEDS_RETRY;
@@ -1469,6 +1470,14 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
 		rtn = scsi_check_sense(scmd);
 		if (rtn == NEEDS_RETRY)
 			goto maybe_retry;
+		else if (rtn == TARGET_ERROR) {
+			/*
+			 * Need to modify host byte to signal a
+			 * permanent target failure
+			 */
+			scmd->result |= (DID_TARGET_FAILURE << 16);
+			rtn = SUCCESS;
+		}
 		/* if rtn == FAILED, we have no sense information;
 		 * returning FAILED will wake the error handler thread
 		 * to collect the sense and redo the decide
@@ -1486,6 +1495,7 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
 	case RESERVATION_CONFLICT:
 		sdev_printk(KERN_INFO, scmd->device,
 			    "reservation conflict\n");
+		scmd->result |= (DID_NEXUS_FAILURE << 16);
 		return SUCCESS; /* causes immediate i/o error */
 	default:
 		return FAILED;