On Thu, Aug 14, 2014 at 07:58:56PM -0700, Luis R. Rodriguez wrote:

Christoph had noted that this seemed associated to the problem
that the btrfs uses different assignments for st_dev than s_dev,
but much as I'd like to see that changed based on discussions so
far its unclear if this is going to be possible unless strong
commitment is reached.

Explain, please.  Whose commitment and commitment to what, exactly?
Having different ->st_dev values for different files on the same
fs is a bloody bad idea; why does btrfs do that at all?  If nothing else,
it breaks the usual "are those two files on the same fs?" tests...