[PATCH 4/5] scsi: translate errors for power management

[Oliver Neukum <oliver@xxxxxxxxxx>]

Synchronizing caches may fail. The reason for these
failures need to be translated to the generic layer
so that it nows whether to ignore a failure, retry later
or give up, aborting sleep.

Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
---
 drivers/scsi/scsi_error.c |   32 ++++++++++++++++++++++++++++++++
 drivers/scsi/sd.c         |    3 +--
 include/scsi/scsi_eh.h    |    1 +
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 4a6381c..195cc75 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -2217,3 +2217,35 @@ void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
 	}
 }
 EXPORT_SYMBOL(scsi_build_sense_buffer);
+
+/**
+ * scsi_translate_errors_to_power_management - errors in a form driver core understands
+ * @res:	Result of scsi command
+ *
+ * Return value:
+ * 	error code driver core understands
+ **/
+int scsi_translate_errors_to_power_management(int res)
+{
+	switch (host_byte(res)) {
+	/* ignore errors due to racing a disconnection */
+	case DID_BAD_TARGET:
+	case DID_NO_CONNECT:
+		return 0;
+	/* signal the upper layer it might try again */
+	case DID_BUS_BUSY:
+	case DID_IMM_RETRY:
+	case DID_REQUEUE:
+	case DID_SOFT_ERROR:
+	case DID_TIME_OUT:
+	case DID_ABORT:
+	case DID_RESET:
+	case DID_TRANSPORT_DISRUPTED:
+		return -EBUSY;
+	case DID_OK:
+		return 0;
+	default:
+		return -EIO;
+	}
+}
+EXPORT_SYMBOL(scsi_translate_errors_to_power_management);
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index c39a97e..8597294 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1288,10 +1288,9 @@ static int sd_sync_cache(struct scsi_disk *sdkp)
 		 */
 		if ((scsi_sense_valid(&sshdr) && sshdr.asc == 0x3a))
 			return 0;
+		return scsi_translate_errors_to_power_management(res);
 	}
 
-	if (res)
-		return -EIO;
 	return 0;
 }
 
diff --git a/include/scsi/scsi_eh.h b/include/scsi/scsi_eh.h
index 06a8790..bdf6d6c 100644
--- a/include/scsi/scsi_eh.h
+++ b/include/scsi/scsi_eh.h
@@ -59,6 +59,7 @@ extern int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
 				   u64 * info_out);
 
 extern void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq);
+extern int scsi_translate_errors_to_power_management(int res);
 
 /*
  * Reset request from external source
-- 
1.7.7

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