xprtrdma: Support unplugging an HCA from under an NFS mount

The device driver for the underlying physical device associated
with an RPC-over-RDMA transport can be removed while RPC-over-RDMA
transports are still in use (ie, while NFS filesystems are still
mounted and active). The IB core performs a connection event upcall
to request that consumers free all RDMA resources associated with
a transport.

There may be pending RPCs when this occurs. Care must be taken to
release associated resources without leaving references that can
trigger a subsequent crash if a signal or soft timeout occurs. We
rely on the caller of the transport's ->close method to ensure that
the previous RPC task has invoked xprt_release but the transport
remains write-locked.

A DEVICE_REMOVE upcall forces a disconnect then sleeps. When ->close
is invoked, it destroys the transport's H/W resources, then wakes
the upcall, which completes and allows the core driver unload to
continue.

BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=266
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 83e219d7aba4acee248bd2653aaacf6ae3d9f6d5..62ecbccd9748e54874059209070ebe4a6b9591e7 100644 (file)
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -457,19 +457,33 @@ out1:
        return ERR_PTR(rc);
 }
 
-/*
- * Close a connection, during shutdown or timeout/reconnect
+/**
+ * xprt_rdma_close - Close down RDMA connection
+ * @xprt: generic transport to be closed
+ *
+ * Called during transport shutdown reconnect, or device
+ * removal. Caller holds the transport's write lock.
  */
 static void
 xprt_rdma_close(struct rpc_xprt *xprt)
 {
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
+       struct rpcrdma_ep *ep = &r_xprt->rx_ep;
+       struct rpcrdma_ia *ia = &r_xprt->rx_ia;
+
+       dprintk("RPC:       %s: closing xprt %p\n", __func__, xprt);
 
-       dprintk("RPC:       %s: closing\n", __func__);
-       if (r_xprt->rx_ep.rep_connected > 0)
+       if (test_and_clear_bit(RPCRDMA_IAF_REMOVING, &ia->ri_flags)) {
+               xprt_clear_connected(xprt);
+               rpcrdma_ia_remove(ia);
+               return;
+       }
+       if (ep->rep_connected == -ENODEV)
+               return;
+       if (ep->rep_connected > 0)
                xprt->reestablish_timeout = 0;
        xprt_disconnect_done(xprt);
-       rpcrdma_ep_disconnect(&r_xprt->rx_ep, &r_xprt->rx_ia);
+       rpcrdma_ep_disconnect(ep, ia);
 }
 
 static void
@@ -680,6 +694,8 @@ xprt_rdma_free(struct rpc_task *task)
  * xprt_rdma_send_request - marshal and send an RPC request
  * @task: RPC task with an RPC message in rq_snd_buf
  *
+ * Caller holds the transport's write lock.
+ *
  * Return values:
  *        0:   The request has been sent
  * ENOTCONN:   Caller needs to invoke connect logic then call again
@@ -706,6 +722,9 @@ xprt_rdma_send_request(struct rpc_task *task)
        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
        int rc = 0;
 
+       if (!xprt_connected(xprt))
+               goto drop_connection;
+
        /* On retransmit, remove any previously registered chunks */
        if (unlikely(!list_empty(&req->rl_registered)))
                r_xprt->rx_ia.ri_ops->ro_unmap_safe(r_xprt, req, false);

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index c8813fb2163f8e5dc2030197191786e18e5e2425..938fd9e6f308b4fb02fd52bf66f5d984558dd523 100644 (file)
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -69,6 +69,8 @@
 /*
  * internal functions
  */
+static void rpcrdma_destroy_mrs(struct rpcrdma_buffer *buf);
+static void rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb);
 
 static struct workqueue_struct *rpcrdma_receive_wq;
 
@@ -262,6 +264,21 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
                        __func__, ep);
                complete(&ia->ri_done);
                break;
+       case RDMA_CM_EVENT_DEVICE_REMOVAL:
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+               pr_info("rpcrdma: removing device for %pIS:%u\n",
+                       sap, rpc_get_port(sap));
+#endif
+               set_bit(RPCRDMA_IAF_REMOVING, &ia->ri_flags);
+               ep->rep_connected = -ENODEV;
+               xprt_force_disconnect(&xprt->rx_xprt);
+               wait_for_completion(&ia->ri_remove_done);
+
+               ia->ri_id = NULL;
+               ia->ri_pd = NULL;
+               ia->ri_device = NULL;
+               /* Return 1 to ensure the core destroys the id. */
+               return 1;
        case RDMA_CM_EVENT_ESTABLISHED:
                connstate = 1;
                ib_query_qp(ia->ri_id->qp, attr,
@@ -291,9 +308,6 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
                goto connected;
        case RDMA_CM_EVENT_DISCONNECTED:
                connstate = -ECONNABORTED;
-               goto connected;
-       case RDMA_CM_EVENT_DEVICE_REMOVAL:
-               connstate = -ENODEV;
 connected:
                dprintk("RPC:       %s: %sconnected\n",
                                        __func__, connstate > 0 ? "" : "dis");
@@ -346,6 +360,7 @@ rpcrdma_create_id(struct rpcrdma_xprt *xprt,
        int rc;
 
        init_completion(&ia->ri_done);
+       init_completion(&ia->ri_remove_done);
 
        id = rdma_create_id(&init_net, rpcrdma_conn_upcall, xprt, RDMA_PS_TCP,
                            IB_QPT_RC);
@@ -468,6 +483,56 @@ out_err:
        return rc;
 }
 
+/**
+ * rpcrdma_ia_remove - Handle device driver unload
+ * @ia: interface adapter being removed
+ *
+ * Divest transport H/W resources associated with this adapter,
+ * but allow it to be restored later.
+ */
+void
+rpcrdma_ia_remove(struct rpcrdma_ia *ia)
+{
+       struct rpcrdma_xprt *r_xprt = container_of(ia, struct rpcrdma_xprt,
+                                                  rx_ia);
+       struct rpcrdma_ep *ep = &r_xprt->rx_ep;
+       struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+       struct rpcrdma_req *req;
+       struct rpcrdma_rep *rep;
+
+       cancel_delayed_work_sync(&buf->rb_refresh_worker);
+
+       /* This is similar to rpcrdma_ep_destroy, but:
+        * - Don't cancel the connect worker.
+        * - Don't call rpcrdma_ep_disconnect, which waits
+        *   for another conn upcall, which will deadlock.
+        * - rdma_disconnect is unneeded, the underlying
+        *   connection is already gone.
+        */
+       if (ia->ri_id->qp) {
+               ib_drain_qp(ia->ri_id->qp);
+               rdma_destroy_qp(ia->ri_id);
+               ia->ri_id->qp = NULL;
+       }
+       ib_free_cq(ep->rep_attr.recv_cq);
+       ib_free_cq(ep->rep_attr.send_cq);
+
+       /* The ULP is responsible for ensuring all DMA
+        * mappings and MRs are gone.
+        */
+       list_for_each_entry(rep, &buf->rb_recv_bufs, rr_list)
+               rpcrdma_dma_unmap_regbuf(rep->rr_rdmabuf);
+       list_for_each_entry(req, &buf->rb_allreqs, rl_all) {
+               rpcrdma_dma_unmap_regbuf(req->rl_rdmabuf);
+               rpcrdma_dma_unmap_regbuf(req->rl_sendbuf);
+               rpcrdma_dma_unmap_regbuf(req->rl_recvbuf);
+       }
+       rpcrdma_destroy_mrs(buf);
+
+       /* Allow waiters to continue */
+       complete(&ia->ri_remove_done);
+}
+
 /**
  * rpcrdma_ia_close - Clean up/close an IA.
  * @ia: interface adapter to close
@@ -1080,7 +1145,8 @@ rpcrdma_get_mw(struct rpcrdma_xprt *r_xprt)
 
 out_nomws:
        dprintk("RPC:       %s: no MWs available\n", __func__);
-       schedule_delayed_work(&buf->rb_refresh_worker, 0);
+       if (r_xprt->rx_ep.rep_connected != -ENODEV)
+               schedule_delayed_work(&buf->rb_refresh_worker, 0);
 
        /* Allow the reply handler and refresh worker to run */
        cond_resched();

diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 9d58260533fc1876252b25c11d48c78d07b40c1d..1c5de1af195b89c2917aad04cf7c01300f63b654 100644 (file)
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -69,6 +69,7 @@ struct rpcrdma_ia {
        struct rdma_cm_id       *ri_id;
        struct ib_pd            *ri_pd;
        struct completion       ri_done;
+       struct completion       ri_remove_done;
        int                     ri_async_rc;
        unsigned int            ri_max_segs;
        unsigned int            ri_max_frmr_depth;
@@ -78,10 +79,15 @@ struct rpcrdma_ia {
        bool                    ri_reminv_expected;
        bool                    ri_implicit_roundup;
        enum ib_mr_type         ri_mrtype;
+       unsigned long           ri_flags;
        struct ib_qp_attr       ri_qp_attr;
        struct ib_qp_init_attr  ri_qp_init_attr;
 };
 
+enum {
+       RPCRDMA_IAF_REMOVING = 0,
+};
+
 /*
  * RDMA Endpoint -- one per transport instance
  */
@@ -511,6 +517,7 @@ extern unsigned int xprt_rdma_memreg_strategy;
  * Interface Adapter calls - xprtrdma/verbs.c
  */
 int rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr);
+void rpcrdma_ia_remove(struct rpcrdma_ia *ia);
 void rpcrdma_ia_close(struct rpcrdma_ia *);
 bool frwr_is_supported(struct rpcrdma_ia *);
 bool fmr_is_supported(struct rpcrdma_ia *);