9p: trans_fd, bail out if recv fcall if missing

req->rc is pre-allocated early on with p9_tag_alloc and shouldn't be missing
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

net/9p/trans_fd.c

@@ -356,14 +356,13 @@ static void p9_read_work(struct work_struct *work)
 		}
 
 		if (m->req->rc == NULL) {
-			m->req->rc = kmalloc(sizeof(struct p9_fcall) +
-						m->client->msize, GFP_NOFS);
-			if (!m->req->rc) {
+			p9_debug(P9_DEBUG_ERROR,
+				 "No recv fcall for tag %d (req %p), disconnecting!\n",
+				 m->rc.tag, m->req);
 			m->req = NULL;
-				err = -ENOMEM;
+			err = -EIO;
 			goto error;
 		}
-		}
 		m->rc.sdata = (char *)m->req->rc + sizeof(struct p9_fcall);
 		memcpy(m->rc.sdata, m->tmp_buf, m->rc.capacity);
 		m->rc.capacity = m->rc.size;