USB: usb-storage: increase max_sectors for tape drives

This patch (as1203) increases the max_sector limit for USB tape
drives.  By default usb-storage sets max_sectors to 240 (i.e., 120 KB)
for all devices.  But tape drives need a higher limit, since tapes can
and do have very large block sizes.  Without the ability to transfer
an entire large block in a single command, such tapes can't be used.

This fixes Bugzilla #12207.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: Phil Mitchell <philipm@sybase.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 727c506417cc..ed710bcdaab2 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -135,6 +135,12 @@ static int slave_configure(struct scsi_device *sdev)
                 if (sdev->request_queue->max_sectors > max_sectors)
                         blk_queue_max_sectors(sdev->request_queue,
                                               max_sectors);
+        } else if (sdev->type == TYPE_TAPE) {
+                /* Tapes need much higher max_sector limits, so just
+                 * raise it to the maximum possible (4 GB / 512) and
+                 * let the queue segment size sort out the real limit.
+                 */
+                blk_queue_max_sectors(sdev->request_queue, 0x7FFFFF);
         }
 
         /* Some USB host controllers can't do DMA; they have to use PIO.