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SubjectRe: [Patch] Cleanup struct gendisk registration, 2.3.40-pre1
Date

----- Original Message -----
From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
To: "Andre Hedrick" <andre@suse.com>
Cc: "Linus Torvalds" <torvalds@transmeta.com>; "Alan Cox"
<alan@lxorguk.ukuu.org.uk>; "Alexander Viro" <aviro@redhat.com>; "Guest
section DW" <dwguest@win.tue.nl>; "Stephen C. Tweedie" <sct@redhat.com>;
<linux-kernel@vger.rutgers.edu>; "Ben LaHaise" <bcrl@redhat.com>; "Alan Cox"
<number6@the-village.bc.nu>; "Eric Youngdale" <eric@andante.org>
Sent: Sunday, January 16, 2000 11:27 AM
Subject: Re: [Patch] Cleanup struct gendisk registration, 2.3.40-pre1


> > I suggested Linux consider the move to a default packet global block
> > device layer and both SCSI and IDE plug into it.
>
> Not all devices are remotely packet based. Later IDE (ATAPI) is, current
> SCSI is, i2o had totally different needs.
>
> Eric is building a nice library, maybe the library for merging/ISA
bouncing
> should be shared but don't jam the policy into the block layer. For some
high
> end cards we already have far too much policy in the block layer.

It should be possible to migrate all of the remaining policy in the
assorted block devices down to the individual drivers. I added enough hooks
for what I needed to do, but some of the policy questions (i.e. the question
as to whether the head entry on the queue is active or not) can now be set
in the actual driver. Those big switch statements in ll_rw_blk.c can all be
made to go away (or at least I think they can, with a little bit of work).
Any remaining policy in the block layer (at least that which is directly
related to queueing) can probably be moved to their respective drivers by
extending request_queue_t if needed.

The only reason I didn't do it was that since I had changed so many
files for the SCSI queueing, the constant merging as new kernel releases
were coming out was becoming a significant burden. Finishing some of this
stuff is buried down on my list of things to do - if no one else gets to it,
I would probably do it the same time that I went in to fix the locking on
those damned tables in the block layer.

-Eric



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