Summary: 2.6.26-rc2 doesn't detect a USB drive's write-protect setting correctly. On Sat, 17 May 2008, Maciej Rutecki wrote: > 2.6.25.4 (works fine): > http://unixy.pl/maciek/download/kernel/2.6.25.4/syslog_debug.txt > http://unixy.pl/maciek/download/kernel/2.6.25.4/usbmon.txt > > 2.6.26-rc2 ("write protect is on" problem; can't mount device): > http://unixy.pl/maciek/download/kernel/2.6.26-rc2/syslog_debug.txt > http://unixy.pl/maciek/download/kernel/2.6.26-rc2/usbmon.txt I'm not sure exactly what changed to cause this regression, but the problem lies in the SCSI layer, not the USB layer. The logs show that in response to the 192-byte MODE SENSE command (used to read the write-protect status), the device sends back no data, good status, and Residue = 192. The SCSI core ignores the Residue and thinks that the old left-over data in the buffer (in this case left over from the READ CAPACITY command) actually indicates the write-protect status -- which it obviously doesn't. Boaz, is scsi_mode_sense() the right place to check for this sort of thing? It probably should be treated the same as an Illegal Request error. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
