Netac OnlyDisk Mini incorrectly detected as write protected

Hi,

On vanilla kernel 2.6.20, Netac OnlyDisk Mini 512MB usb stick lets you
write a file and copy it from the device until it is unmounted.  Upon
mounting the device again, attempts to copy the file written on last
mount results in SCSI I/O errors and the cp command eventually failing
(see error log at the bottom of this message).

The good news is adding the device to drivers/usb/storage/unusual_devs.h
with the US_FL_IGNORE_RESIDUE flag completely cures the problem :)  I've
attached a patch against 2.6.20 to add the device to this file.

The bad news is adding the device to unusual_devs.h and using any of the
flags (I tried many of them) causes the device to be incorrectly
detected as write protected. I tried using  US_FL_NO_WP_DETECT (does
this disable write protect?) but to no avail. I've had to hack
sd_read_write_protect_flag() in drivers/scsi/sd.c to disable write
protect detection in order to use the device with it added to
unusual_devs.h.

Without adding the device to unusual_devs.h, write protect detection
works fine.  The device does have a write protect switch by the way, and
yes I have it set to off.

So my question is can anyone help me figure out the incorrect write
protect detection problem?  I can test, provide whatever info needed.  I
have over 40 of these devices so I'm desperate to iron out this last
issue :)

many thanks,
Eddie


Errors WITHOUT device in unusual_devs.h:

Mar 11 13:16:07 srv1 kernel: usbcore: registered new interface driver
libusual
Mar 11 13:16:07 srv1 kernel: Initializing USB Mass Storage driver...
Mar 11 13:16:07 srv1 kernel: usbcore: registered new interface driver
usb-storage
Mar 11 13:16:07 srv1 kernel: USB Mass Storage support registered.
Mar 11 13:16:23 srv1 kernel: usb 5-2.7: new high speed USB device using
ehci_hcd and address 6
Mar 11 13:16:23 srv1 kernel: usb 5-2.7: configuration #1 chosen from 1
choice
Mar 11 13:16:23 srv1 kernel: scsi2 : SCSI emulation for USB Mass Storage
devices
Mar 11 13:16:23 srv1 kernel: usb-storage: device found at 6
Mar 11 13:16:23 srv1 kernel: usb-storage: waiting for device to settle
before scanning
Mar 11 13:16:28 srv1 kernel: scsi 2:0:0:0: Direct-Access     Netac
OnlyDisk         1.10 PQ: 0 ANSI: 2
Mar 11 13:16:28 srv1 kernel: SCSI device sdc: 1024000 512-byte hdwr
sectors (524 MB)
Mar 11 13:16:28 srv1 kernel: sdc: Write Protect is off
Mar 11 13:16:28 srv1 kernel: sdc: Mode Sense: 00 00 00 00
Mar 11 13:16:28 srv1 kernel: sdc: assuming drive cache: write through
Mar 11 13:16:28 srv1 kernel: SCSI device sdc: 1024000 512-byte hdwr
sectors (524 MB)
Mar 11 13:16:28 srv1 kernel: sdc: Write Protect is off
Mar 11 13:16:28 srv1 kernel: sdc: Mode Sense: 00 00 00 00
Mar 11 13:16:28 srv1 kernel: sdc: assuming drive cache: write through
Mar 11 13:16:28 srv1 kernel:  sdc: sdc1
Mar 11 13:16:28 srv1 kernel: sd 2:0:0:0: Attached scsi removable disk
sdc
Mar 11 13:16:28 srv1 kernel: sd 2:0:0:0: Attached scsi generic sg2 type
0
Mar 11 13:16:28 srv1 kernel: usb-storage: device scan complete
Mar 11 13:19:00 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:00 srv1 kernel: end_request: I/O error, dev sdc, sector
8351
Mar 11 13:19:00 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:00 srv1 kernel: end_request: I/O error, dev sdc, sector
8479
Mar 11 13:19:01 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:01 srv1 kernel: end_request: I/O error, dev sdc, sector
8795
Mar 11 13:19:01 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:01 srv1 kernel: end_request: I/O error, dev sdc, sector
8995
Mar 11 13:19:01 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:01 srv1 kernel: end_request: I/O error, dev sdc, sector
9309
Mar 11 13:19:01 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:01 srv1 kernel: end_request: I/O error, dev sdc, sector
9509
Mar 11 13:19:01 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
            <--------- SNIP ----------->
Mar 11 13:19:35 srv1 kernel: end_request: I/O error, dev sdc, sector
48061
Mar 11 13:19:35 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:35 srv1 kernel: end_request: I/O error, dev sdc, sector
48375
Mar 11 13:19:35 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:35 srv1 kernel: end_request: I/O error, dev sdc, sector
48575
Mar 11 13:19:36 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:36 srv1 kernel: end_request: I/O error, dev sdc, sector
48889
Mar 11 13:19:36 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:36 srv1 kernel: end_request: I/O error, dev sdc, sector
49731
Mar 11 13:19:36 srv1 kernel: Buffer I/O error on device sdc1, logical
block 24836
Mar 11 13:19:36 srv1 kernel: Buffer I/O error on device sdc1, logical
block 24837
Mar 11 13:19:36 srv1 kernel: sd 2:0:0:0: SCSI error: return code =
0x10070000
Mar 11 13:19:36 srv1 kernel: end_request: I/O error, dev sdc, sector
49921
Mar 11 13:21:19 srv1 kernel: usbcore: deregistering interface driver
usb-storage

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--- linux-2.6.20/drivers/usb/storage/unusual_devs.h	2007-03-09 18:58:04.000000000 +0000
+++ linux-2.6.20b/drivers/usb/storage/unusual_devs.h	2007-03-13 23:59:21.000000000 +0000
@@ -1286,6 +1286,14 @@
 		US_SC_DEVICE, US_PR_DEVICE, NULL,
 		US_FL_IGNORE_RESIDUE ),
 
+/* Reported by Edward Chapman <[email protected]>
+   Netac OnlyDisk Mini U2CV2 512MB USB 2.0 Flash Drive */
+UNUSUAL_DEV( 0x0dd8, 0xd202, 0x0000, 0x9999,
+		"Netac",
+		"USB Flash Disk",
+		US_SC_DEVICE, US_PR_DEVICE, NULL,
+		US_FL_IGNORE_RESIDUE ),
+
 /* Reported by Benjamin Schiller <[email protected]>
  * It is also sold by Easylite as DJ 20 */
 UNUSUAL_DEV(  0x0ed1, 0x7636, 0x0103, 0x0103,