9p/rdma: unmap receive dma buffer in rdma_request()/post_recv()

When down_interruptible() or ib_post_send() failed in rdma_request(),
receive dma buffer is not unmapped. Add unmap action to error path.
Also if ib_post_recv() failed in post_recv(), dma buffer is not unmapped.
Add unmap action to error path.

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: fc79d4b104f0 ("9p: rdma: RDMA Transport Support for 9P")
Signed-off-by: Zhengchao Shao <[e-mail]>
Reviewed-by: Leon Romanovsky <[e-mail]>
Signed-off-by: Dominique Martinet <[e-mail]>
Signed-off-by: Eric Van Hensbergen <[e-mail]>

net/9p/trans_rdma.c

···
 	struct p9_trans_rdma *rdma = client->trans;
 	struct ib_recv_wr wr;
 	struct ib_sge sge;
+	int ret;
 
 	c->busa = ib_dma_map_single(rdma->cm_id->device,
 				    c->rc.sdata, client->msize,
···
 	wr.wr_cqe = &c->cqe;
 	wr.sg_list = &sge;
 	wr.num_sge = 1;
-	return ib_post_recv(rdma->qp, &wr, NULL);
+
+	ret = ib_post_recv(rdma->qp, &wr, NULL);
+	if (ret)
+		ib_dma_unmap_single(rdma->cm_id->device, c->busa,
+				    client->msize, DMA_FROM_DEVICE);
+	return ret;
 
  error:
 	p9_debug(P9_DEBUG_ERROR, "EIO\n");
···
 
 	if (down_interruptible(&rdma->sq_sem)) {
 		err = -EINTR;
-		goto send_error;
+		goto dma_unmap;
 	}
 
 	/* Mark request as `sent' *before* we actually send it,
···
 	WRITE_ONCE(req->status, REQ_STATUS_SENT);
 	err = ib_post_send(rdma->qp, &wr, NULL);
 	if (err)
-		goto send_error;
+		goto dma_unmap;
 
 	/* Success */
 	return 0;
 
+dma_unmap:
+	ib_dma_unmap_single(rdma->cm_id->device, c->busa,
+			    c->req->tc.size, DMA_TO_DEVICE);
  /* Handle errors that happened during or while preparing the send: */
  send_error:
 	WRITE_ONCE(req->status, REQ_STATUS_ERROR);