Re: 2.6.3 BUG - can't write DVD-RAM - reported as write-protected

[Jens Axboe <axboe@suse.de>]

On Fri, Mar 05 2004, Olaf Fr?czyk wrote:
> On Fri, 2004-03-05 at 09:23, Jens Axboe wrote:
> > On Thu, Mar 04 2004, Olaf Fr?czyk wrote:
> > > Hi,
> > > I switched to 2.6.3 from 2.4.x serie.
> > > When I mount DVD-RAM it is mounted read-only:
> > > 
> > > [root@venus olaf]# mount /dev/dvdram /mnt/dvdram
> > > mount: block device /dev/dvdram is write-protected, mounting read-only
> > > [root@venus olaf]#
> > > 
> > > In 2.4 it is mounted correctly as read-write.
> > > 
> > > Drive: Panasonic LF-201, reported in Linux as:
> > > MATSHITA        DVD-RAM LF-D200         A120
> > > 
> > > SCSI controller: Adaptec 2940U2W
> > 
> > What does cat /proc/sys/dev/cdrom/info say? Do you get any kernel
> > messages in dmesg when the rw mount fails?
> 
> I get nothing in /var/log/dmesg and in /var/log/messages
> In /proc/sys/dev/cdrom/info I get:
> [olaf@venus olaf]$ cat /proc/sys/dev/cdrom/info
> CD-ROM information, Id: cdrom.c 3.20 2003/12/17
>  
> drive name:             sr1     sr0     hdc
> drive speed:            0       16      44
> drive # of slots:       1       1       1
> Can close tray:         1       1       1
> Can open tray:          1       1       1
> Can lock tray:          1       1       1
> Can change speed:       1       1       1
> Can select disk:        0       0       0
> Can read multisession:  1       1       1
> Can read MCN:           1       1       1
> Reports media changed:  1       1       1
> Can play audio:         1       1       1
> Can write CD-R:         0       1       1
> Can write CD-RW:        0       1       1
> Can read DVD:           1       0       0
> Can write DVD-R:        0       0       0
> Can write DVD-RAM:      1       0       0
> Can read MRW:           0       0       1
> Can write MRW:          0       0       1
> 
> The one I'm mounting is /dev/scd1.
> As there is capablity to write-protect DVD-RAM disk (like a 1.44"
> Floppy), I think that the linux kernel interprets some message from
> device in wrong way.

Please repeat with this patch applied and send back the results, thanks.

===== drivers/cdrom/cdrom.c 1.48 vs edited =====
--- 1.48/drivers/cdrom/cdrom.c	Mon Feb  9 21:58:21 2004
+++ edited/drivers/cdrom/cdrom.c	Sun Mar  7 11:58:40 2004
@@ -645,9 +645,12 @@
 {
 	disc_information di;
 
-	if (cdrom_get_disc_info(cdi, &di))
+	if (cdrom_get_disc_info(cdi, &di)) {
+		printk("cdrom: read di failed\n");
 		return 0;
+	}
 
+	printk("cdrom: erasable: %d\n", di.erasable);
 	return di.erasable;
 }
 

-- 
Jens Axboe