[PATCH v3] xfs: probe data buffer from page cache for unwritten extents

[Christoph Hellwig]

On Tue, Jul 03, 2012 at 03:15:56PM +0800, Jeff Liu wrote:
> Hello,
> 
> This is v3 of the patch.
> 
> We can trigger BUG() in xfs_seek_data() if met two unwritten without data or hole extents at last version.
> So making the extents map reading in loop could solve it.
> 
> Sorry, Am not yet try the repeated holes scenario according to Dave's comments as lack of X64 test env, still
> waiting for it ready.  But this patch is already too long delayed, I have worked it out one weeks ago.
> So I'd like to post it because of it could handle repeated hole/unwritten extents well in a loop, and I also improved
> xfstests:286 with those cases for the verification, will post it soon.
> 
> v2->v3:
> Tested by Mark, hit BUG() for continuous unwritten extents without data wrote.
> * xfs_seek_data(), remove BUG() and having extents map search in loop.

The patch looks good.  But as question by Mark I wonder if it's a good
idea to just improve xfs_seek_data, but not xfs_seek_hole.