mm/hugetlb: setup hugetlb_falloc during fallocate hole punch

mm/hugetlb: setup hugetlb_falloc during fallocate hole punch

When performing a fallocate hole punch, set up a hugetlb_falloc struct and
make i_private point to it.  i_private will point to this struct for the
duration of the operation.  At the end of the operation, wake up anyone
who faulted on the hole and is on the waitq.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>