IB/core: Make testing MR flags for writability a static inline function

Make the MR writability flags check, which is performed in umem.c,
a static inline function in file ib_verbs.h

This allows the function to be used by low-level infiniband drivers.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>

include/rdma/ib_verbs.h

@@ -3734,6 +3734,20 @@ static inline int ib_check_mr_access(int flags)
 	return 0;
 }
 
+static inline bool ib_access_writable(int access_flags)
+{
+	/*
+	 * We have writable memory backing the MR if any of the following
+	 * access flags are set.  "Local write" and "remote write" obviously
+	 * require write access.  "Remote atomic" can do things like fetch and
+	 * add, which will modify memory, and "MW bind" can change permissions
+	 * by binding a window.
+	 */
+	return access_flags &
+		(IB_ACCESS_LOCAL_WRITE   | IB_ACCESS_REMOTE_WRITE |
+		 IB_ACCESS_REMOTE_ATOMIC | IB_ACCESS_MW_BIND);
+}
+
 /**
  * ib_check_mr_status: lightweight check of MR status.
  *     This routine may provide status checks on a selected