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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>
This commit is contained in:
Alan Stern 2009-03-23 09:51:02 -04:00 committed by Greg Kroah-Hartman
parent 090b901182
commit 5c16034d73
1 changed files with 6 additions and 0 deletions
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6
drivers/usb/storage/scsiglue.c
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@ -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.