From 63cae47005af51c937f4cdcc4835f29075add2ba Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sat, 24 Oct 2015 17:28:08 -0400 Subject: xprtrdma: Handle incoming backward direction RPC calls Introduce a code path in the rpcrdma_reply_handler() to catch incoming backward direction RPC calls and route them to the ULP's backchannel server. Signed-off-by: Chuck Lever Reviewed-by: Sagi Grimberg Tested-By: Devesh Sharma Signed-off-by: Anna Schumaker --- net/sunrpc/xprtrdma/backchannel.c | 118 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) (limited to 'net/sunrpc/xprtrdma/backchannel.c') diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c index ffc4853..0b3387f 100644 --- a/net/sunrpc/xprtrdma/backchannel.c +++ b/net/sunrpc/xprtrdma/backchannel.c @@ -5,6 +5,8 @@ */ #include +#include +#include #include "xprt_rdma.h" @@ -12,6 +14,8 @@ # define RPCDBG_FACILITY RPCDBG_TRANS #endif +#define RPCRDMA_BACKCHANNEL_DEBUG + static void rpcrdma_bc_free_rqst(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst) { @@ -253,3 +257,117 @@ void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); spin_unlock_bh(&xprt->bc_pa_lock); } + +/** + * rpcrdma_bc_receive_call - Handle a backward direction call + * @xprt: transport receiving the call + * @rep: receive buffer containing the call + * + * Called in the RPC reply handler, which runs in a tasklet. + * Be quick about it. + * + * Operational assumptions: + * o Backchannel credits are ignored, just as the NFS server + * forechannel currently does + * o The ULP manages a replay cache (eg, NFSv4.1 sessions). + * No replay detection is done at the transport level + */ +void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt, + struct rpcrdma_rep *rep) +{ + struct rpc_xprt *xprt = &r_xprt->rx_xprt; + struct rpcrdma_msg *headerp; + struct svc_serv *bc_serv; + struct rpcrdma_req *req; + struct rpc_rqst *rqst; + struct xdr_buf *buf; + size_t size; + __be32 *p; + + headerp = rdmab_to_msg(rep->rr_rdmabuf); +#ifdef RPCRDMA_BACKCHANNEL_DEBUG + pr_info("RPC: %s: callback XID %08x, length=%u\n", + __func__, be32_to_cpu(headerp->rm_xid), rep->rr_len); + pr_info("RPC: %s: %*ph\n", __func__, rep->rr_len, headerp); +#endif + + /* Sanity check: + * Need at least enough bytes for RPC/RDMA header, as code + * here references the header fields by array offset. Also, + * backward calls are always inline, so ensure there + * are some bytes beyond the RPC/RDMA header. + */ + if (rep->rr_len < RPCRDMA_HDRLEN_MIN + 24) + goto out_short; + p = (__be32 *)((unsigned char *)headerp + RPCRDMA_HDRLEN_MIN); + size = rep->rr_len - RPCRDMA_HDRLEN_MIN; + + /* Grab a free bc rqst */ + spin_lock(&xprt->bc_pa_lock); + if (list_empty(&xprt->bc_pa_list)) { + spin_unlock(&xprt->bc_pa_lock); + goto out_overflow; + } + rqst = list_first_entry(&xprt->bc_pa_list, + struct rpc_rqst, rq_bc_pa_list); + list_del(&rqst->rq_bc_pa_list); + spin_unlock(&xprt->bc_pa_lock); +#ifdef RPCRDMA_BACKCHANNEL_DEBUG + pr_info("RPC: %s: using rqst %p\n", __func__, rqst); +#endif + + /* Prepare rqst */ + rqst->rq_reply_bytes_recvd = 0; + rqst->rq_bytes_sent = 0; + rqst->rq_xid = headerp->rm_xid; + set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); + + buf = &rqst->rq_rcv_buf; + memset(buf, 0, sizeof(*buf)); + buf->head[0].iov_base = p; + buf->head[0].iov_len = size; + buf->len = size; + + /* The receive buffer has to be hooked to the rpcrdma_req + * so that it can be reposted after the server is done + * parsing it but just before sending the backward + * direction reply. + */ + req = rpcr_to_rdmar(rqst); +#ifdef RPCRDMA_BACKCHANNEL_DEBUG + pr_info("RPC: %s: attaching rep %p to req %p\n", + __func__, rep, req); +#endif + req->rl_reply = rep; + + /* Defeat the retransmit detection logic in send_request */ + req->rl_connect_cookie = 0; + + /* Queue rqst for ULP's callback service */ + bc_serv = xprt->bc_serv; + spin_lock(&bc_serv->sv_cb_lock); + list_add(&rqst->rq_bc_list, &bc_serv->sv_cb_list); + spin_unlock(&bc_serv->sv_cb_lock); + + wake_up(&bc_serv->sv_cb_waitq); + + r_xprt->rx_stats.bcall_count++; + return; + +out_overflow: + pr_warn("RPC/RDMA backchannel overflow\n"); + xprt_disconnect_done(xprt); + /* This receive buffer gets reposted automatically + * when the connection is re-established. + */ + return; + +out_short: + pr_warn("RPC/RDMA short backward direction call\n"); + + if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, &r_xprt->rx_ep, rep)) + xprt_disconnect_done(xprt); + else + pr_warn("RPC: %s: reposting rep %p\n", + __func__, rep); +} -- cgit v1.1