Re: Patch for 256 disks in 2.4

[Kurt Garloff]

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Hi Pete,

On Sat, Jul 20, 2002 at 07:57:29PM -0400, Pete Zaitcev wrote:
> For those who do not follow, John Cagle allocated 8 more SCSI
> disk majors.

Have those officially been assigned to SCSI disks?
So disks 128 -- 255 have majors 128 thr. 135?

> Here's a patch to make use of them. I am not sure
> if we want a 2.5 version; it's going to be all devicefs anyhow...

I've written a patch for sd that makes the allocation of majors
dynamic. The driver just takes 8 at sd_init and further majors are=20
allocated when disks are attached. Which saves a lot of memory for
all the gendisk and hd_struct stuff in case you do not have a lot of=20
SCSI disks connected. The patch does support up to 160 SD majors,=20
though currently, it won't succeed getting more than 132 majors.

> It really is strange how many places know major assignments.

Indeed. I missed the sysrq stuff in my patch, BTW.=20
Do you have any idea why we can't just sync all mounted filesystems
in do_emergency_sync()? Or at least all that are backed by a real=20
device? The test for IDE and SCSI majors seems bogus to me. What
about DASD? LVM? EVMS? MD? Loop? NBD? DRBD? What's the rationale=20
of restricting the sync to only IDE and SCSI? Deadlock avoidance?

> I hope I found all of them which matter. Also, I think nobody
> uses min_major/max_major, do you guys know if that's right?

It's right. Kill them! I killed them as well in my patch.

> More comments?

I'm gonna post my patches tomorrow ...

Regards,
--=20
Kurt Garloff  <[e-mail]>                          Eindhoven, NL
GPG key: See mail header, key servers         Linux kernel development
SuSE Linux AG, Nuernberg, DE                            SCSI, Security

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