Re: Lockless file reading

[Jamie Lokier]

Nagendra Singh Tomar wrote:
> While the write had "12" in its buffers and it  would have grabbed the 
> page lock to write it into the page cache, won't it set some flag saying 
> that I don't want to be prempted now. I think there is a small primitive 
> for it in from 2.5 onwards. I don't think it will be a good idea to prempt 
> while it is holding the page lock. How is it possible that it just wrote 
> "1" and did not write "2" though it had grabbed the page lock for that 
> purpose. 

Nope.  I don't see any disabling of preemption while the page is held.

It wouldn't make sense anyway, because the copies to/from userspace
can sleep, so there's nothing to gain by disabling preemption.

-- Jamie
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