mm/hugetlb: expose hugetlb fault mutex for use by fallocate

mm/hugetlb: expose hugetlb fault mutex for use by fallocate

Orabug: 21652814

hugetlb page faults are currently synchronized by the table of mutexes
(htlb_fault_mutex_table).  fallocate code will need to synchronize with
the page fault code when it allocates or deletes pages.  Expose interfaces
so that fallocate operations can be synchronized with page faults.  Minor
name changes to be more consistent with other global hugetlb symbols.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit fec73245c33b067c60f520908a93c971003664c8)
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>