btrfs: allow dedupe of same inode

btrfs: allow dedupe of same inode

clone() supports cloning within an inode so extent-same can do
the same now. This patch fixes up the locking in extent-same to
know about the single-inode case. In addition to that, we add a
check for overlapping ranges, which clone does not allow.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
(Cherry picked from commit 0efa9f48c7e6c15e75946dd2b1c82d3d19e13545)

Orabug: 26251039

Signed-off-by: Shan Hai <shan.hai@oracle.com>
Acked-by: Shannon Nelson <shannon.nelson@oracle.com>
Acked-by: John Haxby <john.haxby@oracle.com>