xprtrdma: Clean up device capability detection

Clean up: Move device capability detection into memreg-specific
source files.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/frwr_ops.c

@@ -73,6 +73,23 @@
 # define RPCDBG_FACILITY	RPCDBG_TRANS
 #endif
 
+bool
+frwr_is_supported(struct rpcrdma_ia *ia)
+{
+	struct ib_device_attr *attrs = &ia->ri_device->attrs;
+
+	if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS))
+		goto out_not_supported;
+	if (attrs->max_fast_reg_page_list_len == 0)
+		goto out_not_supported;
+	return true;
+
+out_not_supported:
+	pr_info("rpcrdma: 'frwr' mode is not supported by device %s\n",
+		ia->ri_device->name);
+	return false;
+}
+
 static int
 __frwr_init(struct rpcrdma_mw *r, struct ib_pd *pd, unsigned int depth)
 {