SUNRPC: Prevent mixed sign comparisons in rpcrdma_convert_iovs()

Keep the type of the buffer position the same during iovec conversion to
reduce the likelihood of unexpected results from comparisons and length
computations.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: Thomas Talpey <Thomas.Talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/xprtrdma/rpc_rdma.c

@@ -83,7 +83,7 @@ static const char transfertypes[][12] = {
  */
 
 static int
-rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, int pos,
+rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
 	enum rpcrdma_chunktype type, struct rpcrdma_mr_seg *seg, int nsegs)
 {
 	int len, n = 0, p;
@@ -169,7 +169,7 @@ rpcrdma_create_chunks(struct rpc_rqst *rqst, struct xdr_buf *target,
 	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
 	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_task->tk_xprt);
 	int nsegs, nchunks = 0;
-	int pos;
+	unsigned int pos;
 	struct rpcrdma_mr_seg *seg = req->rl_segments;
 	struct rpcrdma_read_chunk *cur_rchunk = NULL;
 	struct rpcrdma_write_array *warray = NULL;
@@ -213,7 +213,7 @@ rpcrdma_create_chunks(struct rpc_rqst *rqst, struct xdr_buf *target,
 					(__be32 *)&cur_rchunk->rc_target.rs_offset,
 					seg->mr_base);
 			dprintk("RPC:       %s: read chunk "
-				"elem %d@0x%llx:0x%x pos %d (%s)\n", __func__,
+				"elem %d@0x%llx:0x%x pos %u (%s)\n", __func__,
 				seg->mr_len, (unsigned long long)seg->mr_base,
 				seg->mr_rkey, pos, n < nsegs ? "more" : "last");
 			cur_rchunk++;