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From: Daniel Phillips <phillips@arcor.de>
To: Andrew Morton <akpm@digeo.com>
Subject: Re: invalidate_inode_pages in 2.5.32/3
Date: Tue, 10 Sep 2002 00:19:41 +0200
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Cc: Rik van Riel <riel@conectiva.com.br>, trond.myklebust@fys.uio.no,
       Chuck Lever <cel@citi.umich.edu>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Tuesday 10 September 2002 00:03, Andrew Morton wrote:
> Daniel Phillips wrote:
> > 
> > > I'm very unkeen about using the inaccurate invalidate_inode_pages
> > > for anything which matters, really.   And the consistency of pagecache
> > > data matters.
> > >
> > > NFS should be using something stronger.  And that's basically
> > > vmtruncate() without the i_size manipulation.
> > 
> > Yes, that looks good.  Semantics are basically "and don't come back
> > until every damm page is gone" which is enforced by the requirement
> > that we hold the mapping->page_lock though one entire scan of the
> > truncated region.  (Yes, I remember sweating this one out a year
> > or two ago so it doesn't eat 100% CPU on regular occasions.)
> > 
> > So, specifically, we want:
> > 
> > void invalidate_inode_pages(struct inode *inode)
> > {
> >         truncate_inode_pages(mapping, 0);
> > }
> > 
> > Is it any harder than that?
> 
> Pretty much - need to leave i_size where it was.

This doesn't touch i_size.

> But there are
> apparently reasons why NFS cannot sleepingly lock pages in this particular
> context.

If only we knew what those were.  It's hard to keep the word 'bogosity'
from popping into my head.

-- 
Daniel
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