SUNRPC: Fix a nfs4 over rdma transport oops

Prevent an RPC oops when freeing a dynamically allocated RDMA
buffer, used in certain special-case large metadata operations.

Signed-off-by: Tom Talpey <tmt@netapp.com>
Signed-off-by: James Lentini <jlentini@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 02c522c17de5..a564c1a39ec5 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -614,7 +614,11 @@ xprt_rdma_free(void *buffer)
                 return;
 
         req = container_of(buffer, struct rpcrdma_req, rl_xdr_buf[0]);
-        r_xprt = container_of(req->rl_buffer, struct rpcrdma_xprt, rx_buf);
+        if (req->rl_iov.length == 0) {  /* see allocate above */
+                r_xprt = container_of(((struct rpcrdma_req *) req->rl_buffer)->rl_buffer,
+                                      struct rpcrdma_xprt, rx_buf);
+        } else
+                r_xprt = container_of(req->rl_buffer, struct rpcrdma_xprt, rx_buf);
         rep = req->rl_reply;
 
         dprintk("RPC:       %s: called on 0x%p%s\n",