Re: 64-bit block sizes on 32-bit systems

LA Walsh
2001-03-26T22:11:59Z

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