linux-kernel - Re: Oops when using growisofs

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Date:	Wed, 9 Jul 2008 20:46:12 +0200
From:	Jan Kara <jack@...e.cz>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	Michael Buesch <mb@...sch.de>, Jan Kara <jack@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Oops when using growisofs

On Thu 26-06-08 20:36:11, Jens Axboe wrote:
> On Thu, Jun 26 2008, Michael Buesch wrote:
> > On Thursday 26 June 2008 20:11:42 Jens Axboe wrote:
> > > On Thu, Jun 26 2008, Jan Kara wrote:
> > > > On Wed 25-06-08 11:46:29, Michael Buesch wrote:
> > > > > On Wednesday 25 June 2008 11:37:00 Jan Kara wrote:
> > > > > > > Yeah the IO error is the trigger.
> > > > > > > I noticed that it had obvious troubles accessing the DVD that was in the drive.
> > > > > > > It sweeped over it for several seconds, then hung the system for 2 or 3 seconds
> > > > > > > and then oopsed. But after that everything continued to work as usual.
> > > > > > > (Except kded of course)
> > > > > >   Hmm, by "accessing" do you mean that you've mounted the burned DVD and when
> > > > > > browsing it the IO error and the oops occured or that IO error happened
> > > > > > when burning? It is important because in the first case i_blkbits would be
> > > > > > taken from some ISOFS inode desribing some file while in the second case
> > > > > > i_blkbits are from the inode of the device...
> > > > > I don't know. kded, which caused the oops, is always running. It is a KDE daemon
> > > > > that polls device state and so on. So yeah, it might have accessed the drive
> > > > > while growisofs was writing to it.
> > > > > 
> > > > > However with "accessing" I mean the DVD drive motor was spinning up and down
> > > > > and the laser lens was moving like crazy. The sound that happens, if you put
> > > > > a completely scratched DVD into the drive and it is unable to make sense of it.
> > > > > However, this was not scratched. It was a new DVD with one session on it that
> > > > > I just burnt 5 minutes before that. So I wanted to append another session to it
> > > > > and it crashed and resulted in IO errors in growisofs.
> > > >   I've been looking into this problem for some time. The only way how
> > > >   I see blocksize can be set so big is in cdrom_read_capacity() in
> > > >   drivers/ide/ide-cd.c. That basically blindly fills in
> > > >   queue->hardsect_size with what the drive returns and this can
> > > >   propagate in bd_set_size() to i_blkbits.  Jens, do you think that is
> > > >   possible? Shouldn't ide_cd_read_toc() do some sanity checks of the
> > > >   blocksize returned?
> > > 
> > > It can't hurt, the value should be >= 512b and <= 4kb. Normally it would
> > > be 2kb, but some devices have a 512b switch so that is also seen. Not
> > > sure that 1kb and 4kb are valid, but at least it would still point to
> > > the drive possibly returning valid data and not garbage. So accept all
> > > those, reject (and complain) if it isn't one of those and default to 2kb.
> > 
> > I agree with the need for a hardware sanity check and I would happily test
> > any RFC patch :)
> 
> Something like this, totally untested...
  BTW, just to confirm some positive result: On one of my machines I was
able to trigger the warning message in this patch. So it definitely fixes
some problem.

									Honza

> diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
> index 68e7f19..5c1e663 100644
> --- a/drivers/ide/ide-cd.c
> +++ b/drivers/ide/ide-cd.c
> @@ -1308,13 +1308,29 @@ static int cdrom_read_capacity(ide_drive_t *drive, unsigned long *capacity,
>  	req.cmd_flags |= REQ_QUIET;
>  
>  	stat = ide_cd_queue_pc(drive, &req);
> -	if (stat == 0) {
> -		*capacity = 1 + be32_to_cpu(capbuf.lba);
> -		*sectors_per_frame =
> -			be32_to_cpu(capbuf.blocklen) >> SECTOR_BITS;
> +	if (stat)
> +		return stat;
> +
> +	/*
> +	 * Sanity check the given block size
> +	 */
> +	switch (capbuf.blocklen) {
> +	case 512:
> +	case 1024:
> +	case 2048:
> +	case 4096:
> +		break;
> +	default:
> +		printk(KERN_ERR "ide-cd: weird block size %u\n",
> +							capbuf.blocklen);
> +		printk(KERN_ERR "ide-cd: default to 2kb block size\n");
> +		capbuf.blocklen = 2048;
> +		break;
>  	}
>  
> -	return stat;
> +	*capacity = 1 + be32_to_cpu(capbuf.lba);
> +	*sectors_per_frame = be32_to_cpu(capbuf.blocklen) >> SECTOR_BITS;
> +	return 0;
>  }
>  
>  static int cdrom_read_tocentry(ide_drive_t *drive, int trackno, int msf_flag,
> 
> -- 
> Jens Axboe
> 
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