2 files changed, 13 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 10430d500792..393f9db8f41b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -867,6 +867,17 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
                 /* for passthrough error may be set */
                 error = BLK_STS_OK;
         }
+        /*
+         * Another corner case: the SCSI status byte is non-zero but 'good'.
+         * Example: PRE-FETCH command returns SAM_STAT_CONDITION_MET when
+         * it is able to fit nominated LBs in its cache (and SAM_STAT_GOOD
+         * if it can't fit). Treat SAM_STAT_CONDITION_MET and the related
+         * intermediate statuses (both obsolete in SAM-4) as good.
+         */
+        if (status_byte(result) && scsi_status_is_good(result)) {
+                result = 0;
+                error = BLK_STS_OK;
+        }
 
         /*
          * special case: failed zero length commands always need to
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index cb85eddb47ea..eb7853c1a23b 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -47,6 +47,8 @@ static inline int scsi_status_is_good(int status)
          */
         status &= 0xfe;
         return ((status == SAM_STAT_GOOD) ||
+                (status == SAM_STAT_CONDITION_MET) ||
+                /* Next two "intermediate" statuses are obsolete in SAM-4 */
                 (status == SAM_STAT_INTERMEDIATE) ||
                 (status == SAM_STAT_INTERMEDIATE_CONDITION_MET) ||
                 /* FIXME: this is obsolete in SAM-3 */