scsi: retry MODE SENSE on unit attention

The 'sd' driver is calling scsi_mode_sense() to figure out
internal details. But scsi_mode_sense() never checks for
any pending unit attentions, so we're getting annoying error
messages like:

MODE SENSE: unimplemented page/subpage: 0x00/0x00

and a possible wrong decision for device cache handling.

Reviewed-by: Ewan Milne <emilne@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 448ebda..dffa91c 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2423,7 +2423,7 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
        unsigned char cmd[12];
        int use_10_for_ms;
        int header_length;
-       int result;
+       int result, retry_count = retries;
        struct scsi_sense_hdr my_sshdr;
 
        memset(data, 0, sizeof(*data));
@@ -2502,6 +2502,11 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
                        data->block_descriptor_length = buffer[3];
                }
                data->header_length = header_length;
+       } else if ((status_byte(result) == CHECK_CONDITION) &&
+                  scsi_sense_valid(sshdr) &&
+                  sshdr->sense_key == UNIT_ATTENTION && retry_count) {
+               retry_count--;
+               goto retry;
        }
 
        return result;