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Date: Tue, 10 Sep 2002 00:12:54 -0700
From: Andrew Morton <akpm@digeo.com>
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To: Jens Axboe <axboe@suse.de>
CC: Daniel Phillips <phillips@arcor.de>, Jesse Barnes <jbarnes@sgi.com>,
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Subject: Re: Calculating kernel logical address ..
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Jens Axboe wrote:
> 
> On Mon, Sep 09 2002, Daniel Phillips wrote:
> > On Monday 09 September 2002 21:40, Andrew Morton wrote:
> > > We need a general-purpose "read or write these pages to this blockdev"
> > > library function.
> >
> > I thought bio was supposed to be that.  In what way does it not suffice?
> > Simply because of not having a suitable wrapper?
> 
> a bio _can_ hold a number of pages, it's just that noone has written the
> bio_rw_pages() yet. Not that it would be hard...

It's simple if it's synchronous.  When I discussed this a while
back with the LVM and EVMS developers the consensus was that an
async API would be better - so we'd need some sort of completion
cookie or callback or whatever.

It would end up with almost as much state as the rather amazing
`struct dio'.

Of course, one could do a synchronous API and see if anyone really,
really complains ;)  But a bit of requirements-gathering would be
needed before getting in and coding it.
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