xprtrdma: Clean up SGE accounting in rpcrdma_prepare_msg_sges()

chucklever · amschuma-ntap · commit ad99f0530710 · 2017-11-17T13:47:55.000-05:00
Clean up. rpcrdma_prepare_hdr_sge() sets num_sge to one, then
rpcrdma_prepare_msg_sges() sets num_sge again to the count of SGEs
it added, plus one for the header SGE just mapped in
rpcrdma_prepare_hdr_sge(). This is confusing, and nails in an
assumption about when these functions are called.

Instead, maintain a running count that both functions can update
with just the number of SGEs they have added to the SGE array.

Signed-off-by: Chuck Lever &lt;chuck.lever@oracle.com&gt;
Signed-off-by: Anna Schumaker &lt;Anna.Schumaker@Netapp.com&gt;
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -637,7 +637,7 @@ rpcrdma_prepare_msg_sges(struct rpcrdma_ia *ia, struct rpcrdma_req *req,
 	}
 
 out:
-	req->rl_send_wr.num_sge = sge_no + 1;
+	req->rl_send_wr.num_sge += sge_no;
 	return true;
 
 out_mapping_overflow:

Original file line number	Diff line number	Diff line change
`@@ -637,7 +637,7 @@ rpcrdma_prepare_msg_sges(struct rpcrdma_ia ia, struct rpcrdma_req req,`
`637`	`637`	`}`
`638`	`638`
`639`	`639`	`out:`
`640`		`- req->rl_send_wr.num_sge = sge_no + 1;`
	`640`	`+ req->rl_send_wr.num_sge += sge_no;`
`641`	`641`	`return true;`
`642`	`642`
`643`	`643`	`out_mapping_overflow:`