[patch 10/45] USB: usb-storage: increase max_sectors for tape drives

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>

upstream commit: 5c16034d73da2c1b663aa25dedadbc533b3d811c

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@xxxxxxxxxxxxxxxxxxx>
Reported-and-tested-by: Phil Mitchell <philipm@xxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 drivers/usb/storage/scsiglue.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -135,6 +135,12 @@ static int slave_configure(struct scsi_d
 		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.

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