xprtrdma: Remove support for FMR memory registration

FMR is not supported on most recent RDMA devices. It is also less
secure than FRWR because an FMR memory registration can expose
adjacent bytes to remote reading or writing. As discussed during the
RDMA BoF at LPC 2018, it is time to remove support for FMR in the
NFS/RDMA client stack.

Note that NFS/RDMA server-side uses either local memory registration
or FRWR. FMR is not used.

There are a few Infiniband/RoCE devices in the kernel tree that do
not appear to support MEM_MGT_EXTENSIONS (FRWR), and therefore will
not support client-side NFS/RDMA after this patch. These are:

 - mthca
 - qib
 - hns (RoCE)

Users of these devices can use NFS/TCP on IPoIB instead.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 1 insertions, 11 deletions

diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 99b7f8ea66b0..84f7bbecdd86 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -262,20 +262,12 @@ struct rpcrdma_frwr {
 	};
 };
 
-struct rpcrdma_fmr {
-	struct ib_fmr		*fm_mr;
-	u64			*fm_physaddrs;
-};
-
 struct rpcrdma_mr {
 	struct list_head	mr_list;
 	struct scatterlist	*mr_sg;
 	int			mr_nents;
 	enum dma_data_direction	mr_dir;
-	union {
-		struct rpcrdma_fmr	fmr;
-		struct rpcrdma_frwr	frwr;
-	};
+	struct rpcrdma_frwr	frwr;
 	struct rpcrdma_xprt	*mr_xprt;
 	u32			mr_handle;
 	u32			mr_length;
@@ -490,7 +482,6 @@ struct rpcrdma_memreg_ops {
 	const int	ro_send_w_inv_ok;
 };
 
-extern const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops;
 extern const struct rpcrdma_memreg_ops rpcrdma_frwr_memreg_ops;
 
 /*
@@ -545,7 +536,6 @@ int rpcrdma_ia_open(struct rpcrdma_xprt *xprt);
 void rpcrdma_ia_remove(struct rpcrdma_ia *ia);
 void rpcrdma_ia_close(struct rpcrdma_ia *);
 bool frwr_is_supported(struct rpcrdma_ia *);
-bool fmr_is_supported(struct rpcrdma_ia *);
 
 /*
  * Endpoint calls - xprtrdma/verbs.c