Messages in this thread | | | Date | Thu, 13 Nov 2003 16:27:29 +0100 | From | Jens Axboe <> | Subject | Re: 2.9test9-mm1 and DAO ATAPI cd-burning corrupt |
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On Thu, Nov 13 2003, Linus Torvalds wrote: > > On Thu, 13 Nov 2003, Jens Axboe wrote: > > > On Thu, Nov 13 2003, Pascal Schmidt wrote: > > > > > > My patch from yesterday should handle that situation. > > > cdrom_get_last_written is allowed to override the capacity from > > > cdrom_read_capacity. > > > > Yep, that is fine. > > Well, there is a good argument for not bothering with the > "cdrom_get_last_written" at all: the SCSI layer never does anything like > that as far as I can see, so arguably everybody who ever used ide-scsi > would only ever have seen the READ_CAPACITY command be used. And nobody > ever complained about bad capacitites as far as I can remember.. > > But I might have missed something in the SCSI driver. But I actually see a > > if (cdrom_get_last_written(..) > > in sr.c, and it's been #if 0'ed out since before the Bitkeeper tree > started. And that code definitely does the READ_CAPACITY first. > > The "sd.c" code (which is what a MO device would use) obviously doesn't do > cdrom_get_last_written either - it just does a READ_CAPACITY. (Well, it > does a READ_CAPACITY_16 if it hits a really big disk, but that only hits > if the disk has more than 4G sectors, so we can ignore it for CD-ROM's for > a while. > > So I'd argue for just dropping the cdrom_get_last_written() call entirely.
Your argument isn't very good, imo. I was the one that added the cdrom_get_last_written() calls, because with the pktcdvd written media reading the toc or using READ_CAPACITY just didn't work.
For MO drives, DVD-RAM, and that sort of thing there's no argument - read capacity is the way to go. For CDROMs it's not so clear.
-- Jens Axboe
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