Re: Review: Clear unwritten flag on during partial page truncation

[David Chinner <dgc@sgi.com>]

On Thu, Dec 21, 2006 at 05:16:58PM +1100, Nathan Scott wrote:
> On Wed, 2006-12-20 at 17:28 +1100, David Chinner wrote:
> > Hence the solution is to clear the private buffer flags in
> > xfs_vm_invalidatepage() so that when we extend the file the buffers
> > on the page are all consistent.
> > 
> > Patch below. Comments?
> 
> Looks good Dave, nice sleuthing.
> 
> In hindsight, it'd have been really good to have gone for the real
> BH_Unwritten flag upfront, and then being able to clear that inside
> discard_buffer (like was done for BH_Delay)...  if we did that, then
> all this new code we're adding here (to just clear_buffer_unwritten,
> ultimately) and also the complete hack in xfs_count_page_state could
> be removed.  It still might be worth considering doing that, in case
> there's other hard-to-hit-but-not-yet-uncovered bugs lurking along
> the same lines.  But alot of effort, with the possibility of it not
> being merged at all, as it touches code outside XFS.  D'oh.

Yep, pretty much my thinking as well.

I forgot about that hack in xfs_count_page_state() - we should
be able to remove that with this change, right?

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group