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Message-id: <alpine.DEB.1.00.0804090337110.19638@zirkon.biophys.uni-duesseldorf.de>
Date: Wed, 09 Apr 2008 03:40:34 +0200 (CEST)
From: Michael Schmitz <schmitz@...kon.biophys.uni-duesseldorf.de>
To: Richard Zidlicky <rz@...ux-m68k.org>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
linux-ide@...r.kernel.org,
Linux Kernel Development <linux-kernel@...r.kernel.org>,
Linux/m68k <linux-m68k@...r.kernel.org>,
Michael Schmitz <schmitz@...ian.org>
Subject: Re: [PATCH 5/5] falconide/q40ide: add ->atapi_*put_bytes and
->ata_*put_data methods
Hi,
>> v2:
>> * Add 'struct request *rq' argument to ->ata_{in,out}put_data methods
>> and don't byte-swap disk fs requests (we shouldn't un-swap fs requests
>> because fs itself is stored byte-swapped on the disk) - this is how
>> things were done before the patch (ideally device mapper should be
>> used instead but it would break existing setups and would have some
>> performance impact).
>
> I like the part about checking 'struct request *rq', will make a clean
> distinction between ide command data and ide disk/medium data which is badly
> needed.
>
> However, not only FS data is byteswapped, complete disk including partition
> table and everything else is. Will "rq->cmd_type == REQ_TYPE_FS" also catch
> all these cases?
IIRC only identify data (and perhaps ATAPI data) need to be byteswapped
twice (or not at all), so REQ_TYPE_FS should catch all other cases.
(Good catch about ATAPI there, BTW - I never thought about that, and ISTR
that IDE CD-ROMs never worked in Linux. That would be the reason why..)
Michael
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