[SCSI] sd: Try READ CAPACITY 16 first for SBC-2 devices

New features are being added to the READ CAPACITY 16 results, so we
want to issue it in preference to READ CAPACITY 10.  Unfortunately, some
devices misbehave when they see a READ CAPACITY 16, so we restrict this
command to devices which claim conformance to SPC-3 (aka SBC-2), or claim
they have features which are only reported in the READ CAPACITY 16 data.

The READ CAPACITY 16 command is optional, even for SBC-2 devices, so
we fall back to READ CAPACITY 10 if READ CAPACITY 16 fails.

[jejb: don't error if device supports SBC-2 but doesn't support RC16]
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Tested-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index dcff84a..8eebaa8 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1329,8 +1329,17 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,
                if (media_not_present(sdkp, &sshdr))
                        return -ENODEV;
 
-               if (the_result)
+               if (the_result) {
                        sense_valid = scsi_sense_valid(&sshdr);
+                       if (sense_valid &&
+                           sshdr.sense_key == ILLEGAL_REQUEST &&
+                           (sshdr.asc == 0x20 || sshdr.asc == 0x24) &&
+                           sshdr.ascq == 0x00)
+                               /* Invalid Command Operation Code or
+                                * Invalid Field in CDB, just retry
+                                * silently with RC10 */
+                               return -EINVAL;
+               }
                retries--;
 
        } while (the_result && retries);
@@ -1414,6 +1423,15 @@ static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp,
        return sector_size;
 }
 
+static int sd_try_rc16_first(struct scsi_device *sdp)
+{
+       if (sdp->scsi_level > SCSI_SPC_2)
+               return 1;
+       if (scsi_device_protection(sdp))
+               return 1;
+       return 0;
+}
+
 /*
  * read disk capacity
  */
@@ -1423,11 +1441,14 @@ sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)
        int sector_size;
        struct scsi_device *sdp = sdkp->device;
 
-       /* Force READ CAPACITY(16) when PROTECT=1 */
-       if (scsi_device_protection(sdp)) {
+       if (sd_try_rc16_first(sdp)) {
                sector_size = read_capacity_16(sdkp, sdp, buffer);
                if (sector_size == -EOVERFLOW)
                        goto got_data;
+               if (sector_size == -ENODEV)
+                       return;
+               if (sector_size < 0)
+                       sector_size = read_capacity_10(sdkp, sdp, buffer);
                if (sector_size < 0)
                        return;
        } else {