SUNRPC: Eliminate side effects from rpc_malloc

Currently rpc_malloc sets req->rq_buffer internally.  Make this a more
generic interface:  return a pointer to the new buffer (or NULL) and
make the caller set req->rq_buffer and req->rq_bufsize.  This looks much
more like kmalloc and eliminates the side effects.

To fix a potential deadlock, this patch also replaces GFP_NOFS with
GFP_NOWAIT in rpc_malloc.  This prevents async RPCs from sleeping outside
the RPC's task scheduler while allocating their buffer.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 12487aafaab5..e7dc09ecc470 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -774,7 +774,8 @@ call_allocate(struct rpc_task *task)
         req->rq_rcvsize = RPC_REPHDRSIZE + slack + proc->p_replen;
         req->rq_rcvsize <<= 2;
 
-        xprt->ops->buf_alloc(task, req->rq_callsize + req->rq_rcvsize);
+        req->rq_buffer = xprt->ops->buf_alloc(task,
+                                        req->rq_callsize + req->rq_rcvsize);
         if (req->rq_buffer != NULL)
                 return;