Re: PATCH [2.4.0test10]: Kiobuf#02, fault-in fix

[Eric Lowe <elowe@myrile.madriver.k12.oh.us>]

Hello,

> Yes.  The kernel often has to make these checks the non-intuitive way
> round, because a disk or network read IO actually involves write to
> memory, but a write IO only has to read from memory.  The convention
> is that read/write flags which affect IO paths indicate whether we are
> writing from backing store, so we have to invert the sense to decide
> whether it's a write to memory.
> 
> > This seems to further imply datain means 'read access':
> > 	if (((datain) && (!(vma->vm_flags & VM_WRITE))) ||
> 
> No, because the next line is
> 				err = -EACCES;
> so (rw==READ) and !VM_WRITE is an error --- datain does imply write
> access to memory.

That's why I call it write_access in my patches instead:
there's no ambiguity about what we mean. :)  But in any 
case, it's much better than using (rw==READ) everywhere like
it used to be ...

--
Eric Lowe
Software Engineer, Systran Corporation
elowe@systran.com


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