Re: [patch 2/2] vfs: relax count check in rw_verify_area

[Andrew Morton]

On Wed, 13 Oct 2010 22:46:21 +0200
Edward Shishkin <edward.shishkin@xxxxxxxxx> wrote:

> Increase count limit in rw_verify_area().
> 

OK, now this is a truly awful attempt to describe a patch.

afaict what the patch does is to change rw_verify_area() so that the
kernel now permits single reads and writes of up to 2^63 bytes on
64-bit systems.  Whereas it was previously limited to 2^31.  And the
patch also fixes up a couple of callsites which were assuming that
rw_verify_area() had that particular behaviour.

But that's just my guess, based on a quick read of the implementation. 
I didn't check how far this change penetrates.  Does it affect all
filesystems, for example?  If so were they all reviewed (or tested!)
for correctness?

And why was this patch written?  What motivated you?  What are the
user-visible effects?  Do manpages need updating?

I don't want to have to sit here scratching my head over the
implications and intent of *your* patch.  As at least a starting
point, you should be telling us, please.

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