Re: [PATCH 10/13: eCryptfs] Mmap operations

[Dave Kleikamp <shaggy@austin.ibm.com>]

On Thu, 2006-05-04 at 22:43 +0100, David Howells wrote:
> Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> 
> > > +               rc = mapping->a_ops->readpage(file, page);
> > 
> > What's the purpose of this second read?
> 
> When writing CacheFiles, I noticed that ext3 would occasionally unlock a page
> that had neither PG_uptodate nor PG_error set, and so I had to force another
> readpage() on it.

I understand this comes from the FiST package.  In that code, there is a
comment in one of these functions explaining the second read.  It would
be nice to have that comment in here too:

   /*
    * call readpage() again if we returned from wait_on_page with a
    * page that's not up-to-date; that can happen when a partial
    * page has a few buffers which are ok, but not the whole
    * page.
    */

I'm a bit surprised that this could happen.

Shaggy
-- 
David Kleikamp
IBM Linux Technology Center

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