fwd: 2.4.27rc2, DVD-RW support broke DVD-RAM writes

fwd: 2.4.27rc2, DVD-RW support broke DVD-RAM writes

[Pat LaVarre]

>> With 2.4.27rc2 (and I assume anything later than pre5 - that's when
>> DVD-RW got added) DVD-RAMs have become read-only. Opening a DVD-RAM 
>> for
>> writing results in "EROFS (Read-only file system)" (reported by
>> 'strace'.
...
>  let Pat fix it. Pat?

I'll work first to duplicate this result, then try to fix it, maybe by 
deleting all set_disk_ro.

I'll look for code that ends up rewriting both DVD-RAM and Iomega REV 
discs.

> Also, any chance we get proper 'DVD-RAM is write-protected' support in
> 2.4.x ? It'd be really nice if write()/open(O_WRONLY) would fail in
> those cases.

I'll try Iomega REV discs with the MMC PWP switch flipped on and off.

 > ...

Please redirect me if need be.

Pat LaVarre
http://linux-pel.blog-city.com/read/754579.htm

Re: [usb-storage] 2.4.27rc2, DVD-RW support broke DVD-RAM writes

[Matthew Dharm]

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On Sun, Aug 01, 2004 at 03:26:24PM -0600, Pat LaVarre wrote:
> Jens A/ Matt D:
> 
> Linux 2.4.27-rc4 and 2.4.26 do Not recognise USB DVD-RAM disc 
> rewritability, even though 2.4.27 has recognised USB Iomega REV disc 
> rewritability at least since -rc3.
> 
> Q0: Agreed?

I'll take your word for it.

> Q1: Would you consider a promptly written patch to persuade 2.4.27-rc4 
> to recognise USB DVD-RAM rewritability?  Or is 2.4 development already 
> too over?

I've turned over 2.4 maintance to Pete Zaitcev.

> Q2: Where do you want the patch?  In drivers/usb?  In drivers/scsi?

To me, it sounds like drivers/scsi would be better.  Tho I can see good
arguments for either location.

> Q3: What patch do you want? Should we try op x5A after op x1A fails?  
> Or should we try only op x5A?  Or should we try op x5A first?

I would think on a SCSI Level 2 device, we should start with x5A.

Matt

-- 
Matthew Dharm                              Home: mdharm-usb@one-eyed-alien.net 
Maintainer, Linux USB Mass Storage Driver

It was a new hope.
					-- Dust Puppy
User Friendly, 12/25/1998

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Re: [usb-storage] 2.4.27rc2, DVD-RW support broke DVD-RAM writes

[Jens Axboe]

On Sun, Aug 01 2004, Matthew Dharm wrote:
> On Sun, Aug 01, 2004 at 03:26:24PM -0600, Pat LaVarre wrote:
> > Jens A/ Matt D:
> > 
> > Linux 2.4.27-rc4 and 2.4.26 do Not recognise USB DVD-RAM disc 
> > rewritability, even though 2.4.27 has recognised USB Iomega REV disc 
> > rewritability at least since -rc3.
> > 
> > Q0: Agreed?
> 
> I'll take your word for it.
> 
> > Q1: Would you consider a promptly written patch to persuade 2.4.27-rc4 
> > to recognise USB DVD-RAM rewritability?  Or is 2.4 development already 
> > too over?
> 
> I've turned over 2.4 maintance to Pete Zaitcev.

I think this was a general question. If the patch is to go into
2.4.27-rc now, then it has to be to the point and straight forward (aka
obviously correct). Otherwise we back it out, and get it fixed for
2.4.28-rc.

> > Q2: Where do you want the patch?  In drivers/usb?  In drivers/scsi?
> 
> To me, it sounds like drivers/scsi would be better.  Tho I can see good
> arguments for either location.

Agree

> > Q3: What patch do you want? Should we try op x5A after op x1A fails?  
> > Or should we try only op x5A?  Or should we try op x5A first?
> 
> I would think on a SCSI Level 2 device, we should start with x5A.

Agree. But such a change alone means that it cannot go into 2.4.27, it
has to be in 2.4.28-pre.

-- 
Jens Axboe

Re: [usb-storage] 2.4.27rc2, DVD-RW support broke DVD-RAM writes

[Pat LaVarre]

> drivers/scsi/sr.c ... vendor-specific op x1A 
> reaching the drive, by analogy with SPC op x1A "MODE SENSE (6)", in 
> place of the standard MMC op x5A "MODE SENSE (10)" ...

I've now concretely proposed fixing this in drivers/scsi/.

Subject: [PATCH 2.4] rewritable USB DVD-RAM vs. mode sense op choice
http://marc.theaimsgroup.com/?l=linux-scsi&m=109267404822826

Of course I'll return to drivers/usb/storage/ if the drivers/scsi/ folk
say I should.

Pat LaVarre