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Date: Mon, 26 Mar 2001 14:07:05 -0800
From: LA Walsh <law@sgi.com>
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To: Manfred Spraul <manfred@colorfullife.com>
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Subject: Re: 64-bit block sizes on 32-bit systems
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Manfred Spraul wrote:
> Which field do you access? bh->b_blocknr instead of bh->r_sector?
---
	Yes.
> 
> There were plans to split the buffer_head into 2 structures: buffer
> cache data and the block io data.
> b_blocknr is buffer cache only, no driver should access them.
---
	My 'device' only lives in the buffer cache.  I write
to the device 95% only from kernel space and then it is read
out in large 256K reads by a user-land daemon to copy to a file.
The user-land daemon may also use 'sendfile' to pull the
data out of the device and copy it to a file which should, as I
understand it, result in a kernel only copy from the device
to the output file buffers -- meaning no copy of the data
to user space would be needed.  My primary 'dig' in all this is the 
32-bit block_nr's in the buffer cache.

-l

-- 
L A Walsh                        | Trust Technology, Core Linux, SGI
law@sgi.com                      | Voice: (650) 933-5338
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