scsi: sd: Remember that READ CAPACITY(16) succeeded

The USB storage glue sets the try_rc_10_first flag in an attempt to
avoid wedging poorly implemented legacy USB devices.

If the device capacity is too large to be expressed in the provided
response buffer field of READ CAPACITY(10), a well-behaved device will
set the reported capacity to 0xFFFFFFFF. We will then attempt to issue a
READ CAPACITY(16) to obtain the real capacity.

Since this part of the discovery logic is not covered by the first_scan
flag, a warning will be printed a couple of times times per revalidate
attempt if we upgrade from READ CAPACITY(10) to READ CAPACITY(16).

Remember that we have successfully issued READ CAPACITY(16) so we can
take the fast path on subsequent revalidate attempts.

Reported-by: Menion <menion@gmail.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3b45f7fc5620..13ec1b5ef75c 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2513,6 +2513,8 @@ sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)
 				sector_size = old_sector_size;
 				goto got_data;
 			}
+			/* Remember that READ CAPACITY(16) succeeded */
+			sdp->try_rc_10_first = 0;
 		}
 	}