RDMA/umem: batch page unpin in __ib_umem_release()

Use the newly added unpin_user_page_range_dirty_lock() for more quickly
unpinning a consecutive range of pages represented as compound pages.
This will also calculate number of pages to unpin (for the tail pages
which matching head page) and thus batch the refcount update.

Running a test program which calls memory range reg/unreg on a region 1G
in size and measures cost of both operations together (in a guest using
rxe) with THP and hugetlbfs:

Before:
  590 rounds in 5.003 sec: 8480.335 usec / round
  6898 rounds in 60.001 sec: 8698.367 usec / round

After:
  2688 rounds in 5.002 sec: 1860.786 usec / round
  32517 rounds in 60.001 sec: 1845.225 usec / round

Link: https://lkml.kernel.org/r/20210212130843.13865-5-joao.m.martins@oracle.com


Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Acked-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>