On Wed, 14 Mar 2007, Edward Chapman wrote: > 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).
Those error messages aren't very informative. It would help to have a usbmon log. Instructions for usbmon are in the kernel source file Documentation/usb/usbmon.txt. Post a log showing what happens when you mount the drive, copy a short file (no more than 1 KB), unmount it, mount it again, and try to copy the file back. > 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?) It doesn't disable write-protect -- the only way to do that is by setting the device's switch off. However it does prevent the kernel from asking the device whether it is write-protected. > 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 :) Post another usbmon log showing what happens with your unusual_devs entry present. Alan Stern ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
