IB: Replace ib_umem page_size by page_shift

Size of pages are held by struct ib_umem in page_size field.

It is better to store it as an exponent, because page size by nature
is always power-of-two and used as a factor, divisor or ilog2's argument.

The conversion of page_size to be page_shift allows to have portable
code and avoid following error while compiling on ARM:

  ERROR: "__aeabi_uldivmod" [drivers/infiniband/core/ib_core.ko] undefined!

CC: Selvin Xavier <selvin.xavier@broadcom.com>
CC: Steve Wise <swise@chelsio.com>
CC: Lijun Ou <oulijun@huawei.com>
CC: Shiraz Saleem <shiraz.saleem@intel.com>
CC: Adit Ranadive <aditr@vmware.com>
CC: Dennis Dalessandro <dennis.dalessandro@intel.com>
CC: Ram Amrani <Ram.Amrani@Cavium.com>
Signed-off-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Acked-by: Ram Amrani <Ram.Amrani@cavium.com>
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
Acked-by: Adit Ranadive <aditr@vmware.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 2d83cfd..7f4af1e 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -44,7 +44,7 @@ struct ib_umem {
 	struct ib_ucontext     *context;
 	size_t			length;
 	unsigned long		address;
-	int			page_size;
+	int			page_shift;
 	int                     writable;
 	int                     hugetlb;
 	struct work_struct	work;
@@ -60,7 +60,7 @@ struct ib_umem {
 /* Returns the offset of the umem start relative to the first page. */
 static inline int ib_umem_offset(struct ib_umem *umem)
 {
-	return umem->address & ((unsigned long)umem->page_size - 1);
+	return umem->address & (BIT(umem->page_shift) - 1);
 }
 
 /* Returns the first page of an ODP umem. */