3 files changed, 17 insertions, 2 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3f048bd6326d..5a8f55fea5ff 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1269,9 +1269,18 @@ repeat:
 
         /* Some devices return the total number of sectors, not the
          * highest sector number.  Make the necessary adjustment. */
-        if (sdp->fix_capacity)
+        if (sdp->fix_capacity) {
                 --sdkp->capacity;
 
+        /* Some devices have version which report the correct sizes
+         * and others which do not. We guess size according to a heuristic
+         * and err on the side of lowering the capacity. */
+        } else {
+                if (sdp->guess_capacity)
+                        if (sdkp->capacity & 0x01) /* odd sizes are odd */
+                                --sdkp->capacity;
+        }
+
 got_data:
         if (sector_size == 0) {
                 sector_size = 512;
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 70234f5dbeeb..e227f64d5641 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -153,6 +153,12 @@ static int slave_configure(struct scsi_device *sdev)
                 if (us->flags & US_FL_FIX_CAPACITY)
                         sdev->fix_capacity = 1;
 
+                /* A few disks have two indistinguishable version, one of
+                 * which reports the correct capacity and the other does not.
+                 * The sd driver has to guess which is the case. */
+                if (us->flags & US_FL_CAPACITY_HEURISTICS)
+                        sdev->guess_capacity = 1;
+
                 /* Some devices report a SCSI revision level above 2 but are
                  * unable to handle the REPORT LUNS command (for which
                  * support is mandatory at level 3).  Since we already have
diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
index bab054b8d94f..568366569769 100644
--- a/drivers/usb/storage/unusual_devs.h
+++ b/drivers/usb/storage/unusual_devs.h
@@ -1434,7 +1434,7 @@ UNUSUAL_DEV(  0xed06, 0x4500, 0x0001, 0x0001,
                 "DataStor",
                 "USB4500 FW1.04",
                 US_SC_DEVICE, US_PR_DEVICE, NULL,
-                US_FL_FIX_CAPACITY),
+                US_FL_CAPACITY_HEURISTICS),
 
 /* Control/Bulk transport for all SubClass values */
 USUAL_DEV(US_SC_RBC, US_PR_CB, USB_US_TYPE_STOR),