Introduce SEEK_DATA/SEEK_HOLE to XFS V5

[Christoph Hellwig]

On Wed, Jan 11, 2012 at 03:07:29PM -0600, Mark Tinguely wrote:
> 
> xfs_bmapi_read() returns the br_state == XFS_EXT_NORM for a hole.
> There are a couple places that a hole can trigger a data test.
> BTW, I could not generate a large enough hole that xfs_bmapi_read()
> would return as more than one hole entry, so I will ignore those
> situations and just list the couple places that a hole may be match
> a data rule:

We've been through this before, you need to overflow the 32-bit extent
length counter to get there.  Jeff, did you manage to create a test
case for that particular scenario?