hugetlbfs: truncate_hugepages() takes a range of pages

hugetlbfs: truncate_hugepages() takes a range of pages

Orabug: 21652814

Modify truncate_hugepages() to take a range of pages (start, end) instead
of simply start.  If an end value of LLONG_MAX is passed, the current
"truncate" functionality is maintained.  Existing callers are modified to
pass LLONG_MAX as end of range.  By keying off end == LLONG_MAX, the
routine behaves differently for truncate and hole punch.  Page removal is
now synchronized with page allocation via faults by using the fault mutex
table.  The hole punch case can experience the rare region_del error and
must handle accordingly.

Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in the
case where region_del returns an error.

Since the routine handles more than just the truncate case, it is renamed
to remove_inode_hugepages().  To be consistent, the routine
truncate_huge_page() is renamed remove_huge_page().

Downstream of remove_inode_hugepages(), the routine
hugetlb_unreserve_pages() is also modified to take a range of pages.
hugetlb_unreserve_pages is modified to detect an error from region_del and
pass it back to the caller.

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 6a57804ccdfb77b8f333b736a3ee7cb1bf8732e1)
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>