linux-kernel - Re: What to do about the 2TB limit on HDIO

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Date:	Thu, 27 Mar 2008 20:03:05 +0100
From:	Kay Sievers <kay.sievers@...y.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Mark Lord <lkml@....ca>, Greg KH <gregkh@...e.de>,
	Jens Axboe <axboe@...nel.dk>, Jeff Garzik <jgarzik@...ox.com>,
	Tejun Heo <htejun@...il.com>,
	Linus Torvalds <torvalds@...l.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	IDE/ATA development list <linux-ide@...r.kernel.org>,
	linux-scsi <linux-scsi@...r.kernel.org>
Subject: Re: What to do about the 2TB limit on HDIO_GETGEO ?

On Thu, 2008-03-27 at 11:55 -0700, H. Peter Anvin wrote:
> Kay Sievers wrote:
> >>
> >>  And it's not just a few 10s of lines of code currently,
> >>  but rather about 80-100 lines just to find the correct device subdir,
> >>  and *then* a few more 10s of lines of code to retrieve the value.
> > 
> > Hmm, 100 lines? What else do you need?
> > 
> >   $ grep -l 8:3 /sys/class/block/*/dev
> >   /sys/class/block/sdc/dev
> > 
> 
> That's particularly funny, because your very own example gives the wrong 
> result -- sdc is 8:32 not 8:3 (which is sdc3, which is also excluded by 
> your search.)

Very true, but I guess you get the idea, and know how to add the proper
string match to grep. :)

> Not to mention the fact that it is still O(n).

Any real numbers from a large setup, which show that we want to have a
reverse devnum map in sysfs?

Thanks,
Kay

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