svcrdma: Add class for RDMA backwards direction transport
To support the server-side of an NFSv4.1 backchannel on RDMA connections, add a transport class that enables backward direction messages on an existing forward channel connection. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Acked-by: Bruce Fields <bfields@fieldses.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Chuck Lever
371
net/sunrpc/xprtrdma/svc_rdma_backchannel.c
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371
net/sunrpc/xprtrdma/svc_rdma_backchannel.c
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@@ -0,0 +1,371 @@
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/*
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* Copyright (c) 2015 Oracle. All rights reserved.
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*
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* Support for backward direction RPCs on RPC/RDMA (server-side).
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*/
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#include <linux/sunrpc/svc_rdma.h>
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#include "xprt_rdma.h"
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#define RPCDBG_FACILITY RPCDBG_SVCXPRT
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#undef SVCRDMA_BACKCHANNEL_DEBUG
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int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp,
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struct xdr_buf *rcvbuf)
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{
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struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
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struct kvec *dst, *src = &rcvbuf->head[0];
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struct rpc_rqst *req;
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unsigned long cwnd;
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u32 credits;
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size_t len;
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__be32 xid;
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__be32 *p;
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int ret;
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p = (__be32 *)src->iov_base;
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len = src->iov_len;
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xid = rmsgp->rm_xid;
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#ifdef SVCRDMA_BACKCHANNEL_DEBUG
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pr_info("%s: xid=%08x, length=%zu\n",
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__func__, be32_to_cpu(xid), len);
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pr_info("%s: RPC/RDMA: %*ph\n",
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__func__, (int)RPCRDMA_HDRLEN_MIN, rmsgp);
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pr_info("%s: RPC: %*ph\n",
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__func__, (int)len, p);
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#endif
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ret = -EAGAIN;
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if (src->iov_len < 24)
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goto out_shortreply;
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spin_lock_bh(&xprt->transport_lock);
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req = xprt_lookup_rqst(xprt, xid);
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if (!req)
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goto out_notfound;
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dst = &req->rq_private_buf.head[0];
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memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
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if (dst->iov_len < len)
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goto out_unlock;
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memcpy(dst->iov_base, p, len);
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credits = be32_to_cpu(rmsgp->rm_credit);
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if (credits == 0)
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credits = 1; /* don't deadlock */
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else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
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credits = r_xprt->rx_buf.rb_bc_max_requests;
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cwnd = xprt->cwnd;
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xprt->cwnd = credits << RPC_CWNDSHIFT;
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if (xprt->cwnd > cwnd)
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xprt_release_rqst_cong(req->rq_task);
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ret = 0;
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xprt_complete_rqst(req->rq_task, rcvbuf->len);
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rcvbuf->len = 0;
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out_unlock:
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spin_unlock_bh(&xprt->transport_lock);
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out:
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return ret;
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out_shortreply:
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dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
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xprt, src->iov_len);
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goto out;
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out_notfound:
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dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
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xprt, be32_to_cpu(xid));
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goto out_unlock;
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}
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/* Send a backwards direction RPC call.
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*
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* Caller holds the connection's mutex and has already marshaled
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* the RPC/RDMA request.
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*
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* This is similar to svc_rdma_reply, but takes an rpc_rqst
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* instead, does not support chunks, and avoids blocking memory
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* allocation.
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*
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* XXX: There is still an opportunity to block in svc_rdma_send()
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* if there are no SQ entries to post the Send. This may occur if
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* the adapter has a small maximum SQ depth.
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*/
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static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
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struct rpc_rqst *rqst)
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{
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struct xdr_buf *sndbuf = &rqst->rq_snd_buf;
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struct svc_rdma_op_ctxt *ctxt;
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struct svc_rdma_req_map *vec;
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struct ib_send_wr send_wr;
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int ret;
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vec = svc_rdma_get_req_map(rdma);
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ret = svc_rdma_map_xdr(rdma, sndbuf, vec);
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if (ret)
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goto out_err;
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/* Post a recv buffer to handle the reply for this request. */
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ret = svc_rdma_post_recv(rdma, GFP_NOIO);
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if (ret) {
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pr_err("svcrdma: Failed to post bc receive buffer, err=%d.\n",
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ret);
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pr_err("svcrdma: closing transport %p.\n", rdma);
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set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
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ret = -ENOTCONN;
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goto out_err;
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}
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ctxt = svc_rdma_get_context(rdma);
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ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
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ctxt->count = 1;
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ctxt->wr_op = IB_WR_SEND;
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ctxt->direction = DMA_TO_DEVICE;
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ctxt->sge[0].lkey = rdma->sc_dma_lkey;
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ctxt->sge[0].length = sndbuf->len;
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ctxt->sge[0].addr =
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ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
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sndbuf->len, DMA_TO_DEVICE);
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if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
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ret = -EIO;
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goto out_unmap;
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}
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atomic_inc(&rdma->sc_dma_used);
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memset(&send_wr, 0, sizeof(send_wr));
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send_wr.wr_id = (unsigned long)ctxt;
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send_wr.sg_list = ctxt->sge;
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send_wr.num_sge = 1;
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send_wr.opcode = IB_WR_SEND;
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send_wr.send_flags = IB_SEND_SIGNALED;
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ret = svc_rdma_send(rdma, &send_wr);
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if (ret) {
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ret = -EIO;
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goto out_unmap;
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}
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out_err:
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svc_rdma_put_req_map(rdma, vec);
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dprintk("svcrdma: %s returns %d\n", __func__, ret);
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return ret;
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out_unmap:
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svc_rdma_unmap_dma(ctxt);
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svc_rdma_put_context(ctxt, 1);
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goto out_err;
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}
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/* Server-side transport endpoint wants a whole page for its send
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* buffer. The client RPC code constructs the RPC header in this
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* buffer before it invokes ->send_request.
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*
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* Returns NULL if there was a temporary allocation failure.
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*/
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static void *
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xprt_rdma_bc_allocate(struct rpc_task *task, size_t size)
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{
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struct rpc_rqst *rqst = task->tk_rqstp;
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struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
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struct svcxprt_rdma *rdma;
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struct page *page;
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rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
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/* Prevent an infinite loop: try to make this case work */
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if (size > PAGE_SIZE)
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WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
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size);
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page = alloc_page(RPCRDMA_DEF_GFP);
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if (!page)
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return NULL;
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return page_address(page);
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}
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static void
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xprt_rdma_bc_free(void *buffer)
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{
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/* No-op: ctxt and page have already been freed. */
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}
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static int
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rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
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{
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struct rpc_xprt *xprt = rqst->rq_xprt;
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struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
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struct rpcrdma_msg *headerp = (struct rpcrdma_msg *)rqst->rq_buffer;
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int rc;
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/* Space in the send buffer for an RPC/RDMA header is reserved
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* via xprt->tsh_size.
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*/
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headerp->rm_xid = rqst->rq_xid;
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headerp->rm_vers = rpcrdma_version;
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headerp->rm_credit = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
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headerp->rm_type = rdma_msg;
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headerp->rm_body.rm_chunks[0] = xdr_zero;
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headerp->rm_body.rm_chunks[1] = xdr_zero;
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headerp->rm_body.rm_chunks[2] = xdr_zero;
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#ifdef SVCRDMA_BACKCHANNEL_DEBUG
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pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
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#endif
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rc = svc_rdma_bc_sendto(rdma, rqst);
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if (rc)
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goto drop_connection;
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return rc;
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drop_connection:
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dprintk("svcrdma: failed to send bc call\n");
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xprt_disconnect_done(xprt);
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return -ENOTCONN;
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}
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/* Send an RPC call on the passive end of a transport
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* connection.
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*/
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static int
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xprt_rdma_bc_send_request(struct rpc_task *task)
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{
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struct rpc_rqst *rqst = task->tk_rqstp;
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struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
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struct svcxprt_rdma *rdma;
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int ret;
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dprintk("svcrdma: sending bc call with xid: %08x\n",
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be32_to_cpu(rqst->rq_xid));
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if (!mutex_trylock(&sxprt->xpt_mutex)) {
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rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
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if (!mutex_trylock(&sxprt->xpt_mutex))
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return -EAGAIN;
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rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
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}
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ret = -ENOTCONN;
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rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
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if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
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ret = rpcrdma_bc_send_request(rdma, rqst);
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mutex_unlock(&sxprt->xpt_mutex);
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if (ret < 0)
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return ret;
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return 0;
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}
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static void
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xprt_rdma_bc_close(struct rpc_xprt *xprt)
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{
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dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
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}
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static void
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xprt_rdma_bc_put(struct rpc_xprt *xprt)
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{
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dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
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xprt_free(xprt);
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module_put(THIS_MODULE);
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}
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static struct rpc_xprt_ops xprt_rdma_bc_procs = {
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.reserve_xprt = xprt_reserve_xprt_cong,
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.release_xprt = xprt_release_xprt_cong,
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.alloc_slot = xprt_alloc_slot,
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.release_request = xprt_release_rqst_cong,
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.buf_alloc = xprt_rdma_bc_allocate,
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.buf_free = xprt_rdma_bc_free,
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.send_request = xprt_rdma_bc_send_request,
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.set_retrans_timeout = xprt_set_retrans_timeout_def,
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.close = xprt_rdma_bc_close,
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.destroy = xprt_rdma_bc_put,
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.print_stats = xprt_rdma_print_stats
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};
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static const struct rpc_timeout xprt_rdma_bc_timeout = {
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.to_initval = 60 * HZ,
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.to_maxval = 60 * HZ,
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};
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/* It shouldn't matter if the number of backchannel session slots
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* doesn't match the number of RPC/RDMA credits. That just means
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* one or the other will have extra slots that aren't used.
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*/
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static struct rpc_xprt *
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xprt_setup_rdma_bc(struct xprt_create *args)
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{
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struct rpc_xprt *xprt;
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struct rpcrdma_xprt *new_xprt;
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if (args->addrlen > sizeof(xprt->addr)) {
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dprintk("RPC: %s: address too large\n", __func__);
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return ERR_PTR(-EBADF);
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}
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xprt = xprt_alloc(args->net, sizeof(*new_xprt),
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RPCRDMA_MAX_BC_REQUESTS,
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RPCRDMA_MAX_BC_REQUESTS);
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if (!xprt) {
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dprintk("RPC: %s: couldn't allocate rpc_xprt\n",
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__func__);
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return ERR_PTR(-ENOMEM);
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}
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xprt->timeout = &xprt_rdma_bc_timeout;
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xprt_set_bound(xprt);
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xprt_set_connected(xprt);
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xprt->bind_timeout = RPCRDMA_BIND_TO;
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xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
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xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
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xprt->prot = XPRT_TRANSPORT_BC_RDMA;
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xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
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xprt->ops = &xprt_rdma_bc_procs;
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memcpy(&xprt->addr, args->dstaddr, args->addrlen);
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xprt->addrlen = args->addrlen;
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xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
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xprt->resvport = 0;
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xprt->max_payload = xprt_rdma_max_inline_read;
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new_xprt = rpcx_to_rdmax(xprt);
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new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
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xprt_get(xprt);
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args->bc_xprt->xpt_bc_xprt = xprt;
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xprt->bc_xprt = args->bc_xprt;
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if (!try_module_get(THIS_MODULE))
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goto out_fail;
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/* Final put for backchannel xprt is in __svc_rdma_free */
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xprt_get(xprt);
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return xprt;
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out_fail:
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xprt_rdma_free_addresses(xprt);
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args->bc_xprt->xpt_bc_xprt = NULL;
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xprt_put(xprt);
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xprt_free(xprt);
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return ERR_PTR(-EINVAL);
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}
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struct xprt_class xprt_rdma_bc = {
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.list = LIST_HEAD_INIT(xprt_rdma_bc.list),
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.name = "rdma backchannel",
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.owner = THIS_MODULE,
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.ident = XPRT_TRANSPORT_BC_RDMA,
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.setup = xprt_setup_rdma_bc,
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};
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