RDS: Add GET_MR_FOR_DEST sockopt

RDS currently supports a GET_MR sockopt to establish a
memory region (MR) for a chunk of memory. However, the fastreg
method ties a MR to a particular destination. The GET_MR_FOR_DEST
sockopt allows the remote machine to be specified, and thus
support for fastreg (aka FRWRs).

Note that this patch does *not* do all of this - it simply
implements the new sockopt in terms of the old one, so applications
can begin to use the new sockopt in preparation for cutover to
FRWRs.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/rds.h b/include/linux/rds.h
index 89d46e1afbb1..cab4994c2f63 100644
--- a/include/linux/rds.h
+++ b/include/linux/rds.h
@@ -56,6 +56,7 @@
 /* deprecated: RDS_BARRIER 4 */
 #define RDS_RECVERR                     5
 #define RDS_CONG_MONITOR                6
+#define RDS_GET_MR_FOR_DEST             7
 
 /*
  * Control message types for SOL_RDS.
@@ -224,6 +225,13 @@ struct rds_get_mr_args {
         uint64_t        flags;
 };
 
+struct rds_get_mr_for_dest_args {
+        struct sockaddr_storage dest_addr;
+        struct rds_iovec        vec;
+        u_int64_t               cookie_addr;
+        uint64_t                flags;
+};
+
 struct rds_free_mr_args {
         rds_rdma_cookie_t cookie;
         u_int64_t       flags;