Subject: Re: 2.6.3 BUG - can't write DVD-RAM - reported as write-protected
From: Olaf =?iso-8859-2?Q?Fr=B1czyk?= <olaf@cbk.poznan.pl>
To: Jens Axboe <axboe@suse.de>
Cc: linux-kernel@vger.kernel.org, td@linuxgang.com
In-Reply-To: <20040323152339.GI1481@suse.de>
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Date: Tue, 23 Mar 2004 16:36:27 +0100
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On Tue, 2004-03-23 at 16:23, Jens Axboe wrote:
> On Tue, Mar 23 2004, Olaf Fr?czyk wrote:
> > > You broke it, the first check simply returns the header so .erasable
> > > must be 0 because we cleared the buffer first.
> > > 
> > > ===== drivers/cdrom/cdrom.c 1.49 vs edited =====
> > > --- 1.49/drivers/cdrom/cdrom.c	Thu Mar 11 13:31:15 2004
> > > +++ edited/drivers/cdrom/cdrom.c	Sun Mar 14 12:21:44 2004
> > > @@ -2658,11 +2658,13 @@
> > >  	/* set up command and get the disc info */
> > >  	init_cdrom_command(&cgc, di, sizeof(*di), CGC_DATA_READ);
> > >  	cgc.cmd[0] = GPCMD_READ_DISC_INFO;
> > > -	cgc.cmd[8] = cgc.buflen = 2;
> > > -	cgc.quiet = 1;
> > > +	cgc.cmd[8] = cgc.buflen = 8;
> > > +	cgc.quiet = 0;
> > >  
> > > -	if ((ret = cdo->generic_packet(cdi, &cgc)))
> > > +	if ((ret = cdo->generic_packet(cdi, &cgc))) {
> > > +		printk("cdrom: read_di failed, %d\n", ret);
> > >  		return ret;
> > > +	}
> > >  
> > >  	/* not all drives have the same disc_info length, so requeue
> > >  	 * packet with the length the drive tells us it can supply
> > > @@ -2673,6 +2675,7 @@
> > >  	if (cgc.buflen > sizeof(disc_information))
> > >  		cgc.buflen = sizeof(disc_information);
> > >  
> > > +	printk("cdrom: re-reading di, len=%d\n", cgc.buflen);
> > >  	cgc.cmd[8] = cgc.buflen;
> > >  	return cdo->generic_packet(cdi, &cgc);
> > >  }
> > On 2.6.4 with your patch I get:
> > Mar 23 15:46:03 venus kernel: cdrom: read_di failed, -95
> 
> Ok, so your drive doesn't support GPCMD_READ_DISC_INFO at all. Probably
> the best bet is simply to allow writable open if cdrom_get_disc_info()
> fails after all, even though I hate doing stuff like that.
> 
> ===== drivers/cdrom/cdrom.c 1.50 vs edited =====
> --- 1.50/drivers/cdrom/cdrom.c	Tue Mar 16 09:41:01 2004
> +++ edited/drivers/cdrom/cdrom.c	Tue Mar 23 16:23:07 2004
> @@ -725,7 +725,7 @@
>  	disc_information di;
>  
>  	if (cdrom_get_disc_info(cdi, &di))
> -		return 0;
> +		return -1;
>  
>  	return di.erasable;
>  }
> @@ -735,7 +735,16 @@
>   */
>  static int cdrom_dvdram_open_write(struct cdrom_device_info *cdi)
>  {
> -	return !cdrom_media_erasable(cdi);
> +	int ret = cdrom_media_erasable(cdi);
> +
> +	/*
> +	 * allow writable open if media info read worked and media is
> +	 * erasable, _or_ if it fails since not all drives support it
> +	 */
> +	if (!ret)
> +		return 1;
> +
> +	return 0;
>  }
>  
>  static int cdrom_mrw_open_write(struct cdrom_device_info *cdi)
Just to be sure. In 2.4 it was not checked?
Will your patch go in 2.6.5/2.6.6 or I'll have to patch it manually till
end of my life ? :)
Regards,

Olaf

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