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From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Tejun Heo <tj@kernel.org>
Cc: jeff@garzik.org, linux-ide@vger.kernel.org,
	jens.axboe@oracle.com, linux-kernel@vger.kernel.org,
	linux-scsi@vger.kernel.org, Mauelshagen@RedHat.com,
	dm-devel@RedHat.com, dan.j.williams@gmail.com
Subject: Re: [PATCH 2/3] scsi: add scsi_device->alt_capacity
Date: Sat, 09 May 2009 16:23:43 +0000	[thread overview]
Message-ID: <1241886223.3542.37.camel@mulgrave.int.hansenpartnership.com> (raw)
In-Reply-To: <4A05AAA4.9010806@kernel.org>

On Sun, 2009-05-10 at 01:09 +0900, Tejun Heo wrote:
> James Bottomley wrote:
> > This is done at slightly the wrong level.  Capacity is actually a
> > property of struct scsi_disk not struct scsi_device ... shouldn't
> > alt_capacity be at the same level?
> 
> Hmmm... I think that was my first try and then I moved it to sdev for
> some reason I can't rememer now.  I'll look into it again and try to
> move it into sdev.

Really one of the things I was wondering is why even scsi_disk ...
capacity is in there, but it's also in gendisk, so I've thought
(admittedly never translated it to action) that we could just remove the
duplication in scsi_disk.

This alt_capacity looks to be a pure ATA thing ... I can't find it in
the SCSI specs and there doesn't seem to be a SAT equivalent of the
commands.  Ideally, what should be happening is that the ata ULD would
issue the capacity commands and just set the block alt_capacity without
having to worry about transporting the value up and down the stack.
Matthew Wilcox thought we could begin an implementation of the ATA uld
using the ATA_16 command to transport it through SCSI ... this might
provide the good reason to begin that.

James



  reply	other threads:[~2009-05-09 16:23 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-09  0:13 [GIT PATCH] block,scsi,libata: implement alt_size, take#2 Tejun Heo
2009-05-09  0:13 ` Tejun Heo
2009-05-09  0:13 ` [PATCH 1/3] block: add alt_size Tejun Heo
2009-05-09  0:13   ` Tejun Heo
2009-05-09 13:45   ` Kay Sievers
2009-05-09 13:45     ` Kay Sievers
2009-05-09 14:04     ` Tejun Heo
2009-05-09 14:04       ` Tejun Heo
2009-05-09 16:26       ` Kay Sievers
2009-05-11 13:45       ` [dm-devel] " Konrad Rzeszutek
2009-05-12  0:53         ` Tejun Heo
2009-05-12  0:53           ` [dm-devel] " Tejun Heo
2009-05-09  0:13 ` [PATCH 2/3] scsi: add scsi_device->alt_capacity Tejun Heo
2009-05-09  0:13   ` Tejun Heo
2009-05-09  4:23   ` James Bottomley
2009-05-09 16:09     ` Tejun Heo
2009-05-09 16:09       ` Tejun Heo
2009-05-09 16:23       ` James Bottomley [this message]
2009-05-10  1:26         ` Tejun Heo
2009-05-15 19:44         ` ATA ULD (was Re: [PATCH 2/3] scsi: add scsi_device->alt_capacity) Jeff Garzik
2009-05-09  0:13 ` [PATCH 3/3] libata: export HPA size as alt_size Tejun Heo
2009-05-09  0:13   ` Tejun Heo
  -- strict thread matches above, loose matches on Subject: below --
2009-02-01  2:55 [PATCHSET] block,scsi,libata: implement alt_size Tejun Heo
2009-02-01  2:55 ` [PATCH 2/3] scsi: add scsi_device->alt_capacity Tejun Heo
2009-02-01  2:55   ` Tejun Heo

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