xprtrdma: Honor ->send_request API contract

Commit c93c62231cf5 ("xprtrdma: Disconnect on registration failure")
added a disconnect for some RPC marshaling failures. This is needed
only in a handful of cases, but it was triggering for simple stuff
like temporary resource shortages. Try to straighten this out.

Fix up the lower layers so they don't return -ENOMEM or other error
codes that the RPC client's FSM doesn't explicitly recognize.

Also fix up the places in the send_request path that do want a
disconnect. For example, when ib_post_send or ib_post_recv fail,
this is a sign that there is a send or receive queue resource
miscalculation. That should be rare, and is a sign of a software
bug. But xprtrdma can recover: disconnect to reset the transport and
start over.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

5 files changed, 39 insertions, 24 deletions

diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
index 8b6ce8ebe60f..aae4c372a40f 100644
--- a/net/sunrpc/xprtrdma/fmr_ops.c
+++ b/net/sunrpc/xprtrdma/fmr_ops.c
@@ -219,7 +219,7 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
                 rpcrdma_defer_mr_recovery(mw);
         mw = rpcrdma_get_mw(r_xprt);
         if (!mw)
-                return -ENOMEM;
+                return -ENOBUFS;
 
         pageoff = offset_in_page(seg1->mr_offset);
         seg1->mr_offset -= pageoff;     /* start of page */
@@ -269,14 +269,14 @@ out_dmamap_err:
         pr_err("rpcrdma: failed to dma map sg %p sg_nents %u\n",
                mw->mw_sg, mw->mw_nents);
         rpcrdma_defer_mr_recovery(mw);
-        return -ENOMEM;
+        return -EIO;
 
 out_maperr:
         pr_err("rpcrdma: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
                len, (unsigned long long)dma_pages[0],
                pageoff, mw->mw_nents, rc);
         rpcrdma_defer_mr_recovery(mw);
-        return rc;
+        return -EIO;
 }
 
 /* Invalidate all memory regions that were registered for "req".
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index fc2826b3518c..d7613db9185d 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -382,7 +382,7 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
                         rpcrdma_defer_mr_recovery(mw);
                 mw = rpcrdma_get_mw(r_xprt);
                 if (!mw)
-                        return -ENOMEM;
+                        return -ENOBUFS;
         } while (mw->frmr.fr_state != FRMR_IS_INVALID);
         frmr = &mw->frmr;
         frmr->fr_state = FRMR_IS_VALID;
@@ -456,18 +456,18 @@ out_dmamap_err:
         pr_err("rpcrdma: failed to dma map sg %p sg_nents %u\n",
                mw->mw_sg, mw->mw_nents);
         rpcrdma_defer_mr_recovery(mw);
-        return -ENOMEM;
+        return -EIO;
 
 out_mapmr_err:
         pr_err("rpcrdma: failed to map mr %p (%u/%u)\n",
                frmr->fr_mr, n, mw->mw_nents);
-        rc = n < 0 ? n : -EIO;
         rpcrdma_defer_mr_recovery(mw);
-        return rc;
+        return -EIO;
 
 out_senderr:
+        pr_err("rpcrdma: FRMR registration ib_post_send returned %i\n", rc);
         rpcrdma_defer_mr_recovery(mw);
-        return rc;
+        return -ENOTCONN;
 }
 
 static struct ib_send_wr *
@@ -569,7 +569,8 @@ unmap:
         return;
 
 reset_mrs:
-        pr_warn("%s: ib_post_send failed %i\n", __func__, rc);
+        pr_err("rpcrdma: FRMR invalidate ib_post_send returned %i\n", rc);
+        rdma_disconnect(ia->ri_id);
 
         /* Find and reset the MRs in the LOCAL_INV WRs that did not
          * get posted. This is synchronous, and slow.
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 35a81096e83d..77e002f4d005 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -251,7 +251,7 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
                         /* alloc the pagelist for receiving buffer */
                         ppages[p] = alloc_page(GFP_ATOMIC);
                         if (!ppages[p])
-                                return -ENOMEM;
+                                return -EAGAIN;
                 }
                 seg[n].mr_page = ppages[p];
                 seg[n].mr_offset = (void *)(unsigned long) page_base;
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 4c8e7f11b906..be4dd2c7c680 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -558,7 +558,6 @@ out_sendbuf:
 
 out_fail:
         rpcrdma_buffer_put(req);
-        r_xprt->rx_stats.failed_marshal_count++;
         return NULL;
 }
 
@@ -590,8 +589,19 @@ xprt_rdma_free(void *buffer)
         rpcrdma_buffer_put(req);
 }
 
-/*
+/**
+ * xprt_rdma_send_request - marshal and send an RPC request
+ * @task: RPC task with an RPC message in rq_snd_buf
+ *
+ * Return values:
+ *        0:    The request has been sent
+ * ENOTCONN:    Caller needs to invoke connect logic then call again
+ *  ENOBUFS:    Call again later to send the request
+ *      EIO:    A permanent error occurred. The request was not sent,
+ *              and don't try it again
+ *
  * send_request invokes the meat of RPC RDMA. It must do the following:
+ *
  *  1.  Marshal the RPC request into an RPC RDMA request, which means
  *      putting a header in front of data, and creating IOVs for RDMA
  *      from those in the request.
@@ -600,7 +610,6 @@ xprt_rdma_free(void *buffer)
  *      the request (rpcrdma_ep_post).
  *  4.  No partial sends are possible in the RPC-RDMA protocol (as in UDP).
  */
-
 static int
 xprt_rdma_send_request(struct rpc_task *task)
 {
@@ -630,11 +639,12 @@ xprt_rdma_send_request(struct rpc_task *task)
         return 0;
 
 failed_marshal:
-        r_xprt->rx_stats.failed_marshal_count++;
         dprintk("RPC:       %s: rpcrdma_marshal_req failed, status %i\n",
                 __func__, rc);
         if (rc == -EIO)
-                return -EIO;
+                r_xprt->rx_stats.failed_marshal_count++;
+        if (rc != -ENOTCONN)
+                return rc;
 drop_connection:
         xprt_disconnect_done(xprt);
         return -ENOTCONN;       /* implies disconnect */
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 6fb73ff26183..db935ed3ac75 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1151,7 +1151,7 @@ rpcrdma_ep_post(struct rpcrdma_ia *ia,
         if (rep) {
                 rc = rpcrdma_ep_post_recv(ia, ep, rep);
                 if (rc)
-                        goto out;
+                        return rc;
                 req->rl_reply = NULL;
         }
 
@@ -1176,10 +1176,12 @@ rpcrdma_ep_post(struct rpcrdma_ia *ia,
 
         rc = ib_post_send(ia->ri_id->qp, &send_wr, &send_wr_fail);
         if (rc)
-                dprintk("RPC:       %s: ib_post_send returned %i\n", __func__,
-                        rc);
-out:
-        return rc;
+                goto out_postsend_err;
+        return 0;
+
+out_postsend_err:
+        pr_err("rpcrdma: RDMA Send ib_post_send returned %i\n", rc);
+        return -ENOTCONN;
 }
 
 /*
@@ -1204,11 +1206,13 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
                                    DMA_BIDIRECTIONAL);
 
         rc = ib_post_recv(ia->ri_id->qp, &recv_wr, &recv_wr_fail);
-
         if (rc)
-                dprintk("RPC:       %s: ib_post_recv returned %i\n", __func__,
-                        rc);
-        return rc;
+                goto out_postrecv;
+        return 0;
+
+out_postrecv:
+        pr_err("rpcrdma: ib_post_recv returned %i\n", rc);
+        return -ENOTCONN;
 }
 
 /**