[SCSI] sd,sr: add early detection of medium not present

The current scsi_test_unit_ready() is updated to return sense code
information (in struct scsi_sense_hdr).  The sd and sr drivers are
changed to interpret the sense code return asc 0x3a as no media and
adjust the device status accordingly.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 7702681d93f..896be4ab285 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -179,18 +179,24 @@ static int sr_media_change(struct cdrom_device_info *cdi, int slot)
 {
         struct scsi_cd *cd = cdi->handle;
         int retval;
+        struct scsi_sense_hdr *sshdr;
 
         if (CDSL_CURRENT != slot) {
                 /* no changer support */
                 return -EINVAL;
         }
 
-        retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES);
-        if (retval) {
-                /* Unable to test, unit probably not ready.  This usually
-                 * means there is no disc in the drive.  Mark as changed,
-                 * and we will figure it out later once the drive is
-                 * available again.  */
+        sshdr =  kzalloc(sizeof(*sshdr), GFP_KERNEL);
+        retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES,
+                                      sshdr);
+        if (retval || (scsi_sense_valid(sshdr) &&
+                       /* 0x3a is medium not present */
+                       sshdr->asc == 0x3a)) {
+                /* Media not present or unable to test, unit probably not
+                 * ready. This usually means there is no disc in the drive.
+                 * Mark as changed, and we will figure it out later once
+                 * the drive is available again.
+                 */
                 cd->device->changed = 1;
                 /* This will force a flush, if called from check_disk_change */
                 retval = 1;
@@ -213,6 +219,7 @@ out:
                 sdev_evt_send_simple(cd->device, SDEV_EVT_MEDIA_CHANGE,
                                      GFP_KERNEL);
         cd->previous_state = retval;
+        kfree(sshdr);
 
         return retval;
 }