usb-storage: enable multi-LUN scanning when needed
commit 823d12c95c666fa7ab7dad208d735f6bc6afabdc upstream.
People sometimes create their own custom-configured kernels and forget
to enable CONFIG_SCSI_MULTI_LUN. This causes problems when they plug
in a USB storage device (such as a card reader) with more than one
LUN.
Fortunately, we can tell fairly easily when a storage device claims to
have more than one LUN. When that happens, this patch asks the SCSI
layer to probe all the LUNs automatically, regardless of the config
setting.
The patch also updates the Kconfig help text for usb-storage,
explaining that CONFIG_SCSI_MULTI_LUN may be necessary.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Thomas Raschbacher <lordvan@lordvan.com>
CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
CC: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 11418da..3a7fd6f 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -78,6 +78,8 @@
static int slave_alloc (struct scsi_device *sdev)
{
+ struct us_data *us = host_to_us(sdev->host);
+
/*
* Set the INQUIRY transfer length to 36. We don't use any of
* the extra data and many devices choke if asked for more or
@@ -102,6 +104,10 @@
*/
blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
+ /* Tell the SCSI layer if we know there is more than one LUN */
+ if (us->protocol == USB_PR_BULK && us->max_lun > 0)
+ sdev->sdev_bflags |= BLIST_FORCELUN;
+
return 0;
}