RPCRDMA: rpc rdma protocol implementation

This implements the marshaling and unmarshaling of the rpcrdma transport
headers. Connection management is also addressed.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 863 insertions, 4 deletions

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index b0587f3a5d77..12db63580427 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -1,9 +1,868 @@
 /*
- * Placeholders for subsequent patches
+ * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the BSD-type
+ * license below:
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *      Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *      Redistributions in binary form must reproduce the above
+ *      copyright notice, this list of conditions and the following
+ *      disclaimer in the documentation and/or other materials provided
+ *      with the distribution.
+ *
+ *      Neither the name of the Network Appliance, Inc. nor the names of
+ *      its contributors may be used to endorse or promote products
+ *      derived from this software without specific prior written
+ *      permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * rpc_rdma.c
+ *
+ * This file contains the guts of the RPC RDMA protocol, and
+ * does marshaling/unmarshaling, etc. It is also where interfacing
+ * to the Linux RPC framework lives.
  */
 
 #include "xprt_rdma.h"
 
-void rpcrdma_conn_func(struct rpcrdma_ep *a) { }
-void rpcrdma_reply_handler(struct rpcrdma_rep *a) { }
-int rpcrdma_marshal_req(struct rpc_rqst *a) { return EINVAL; }
+#include <linux/highmem.h>
+
+#ifdef RPC_DEBUG
+# define RPCDBG_FACILITY        RPCDBG_TRANS
+#endif
+
+enum rpcrdma_chunktype {
+        rpcrdma_noch = 0,
+        rpcrdma_readch,
+        rpcrdma_areadch,
+        rpcrdma_writech,
+        rpcrdma_replych
+};
+
+#ifdef RPC_DEBUG
+static const char transfertypes[][12] = {
+        "pure inline",  /* no chunks */
+        " read chunk",  /* some argument via rdma read */
+        "*read chunk",  /* entire request via rdma read */
+        "write chunk",  /* some result via rdma write */
+        "reply chunk"   /* entire reply via rdma write */
+};
+#endif
+
+/*
+ * Chunk assembly from upper layer xdr_buf.
+ *
+ * Prepare the passed-in xdr_buf into representation as RPC/RDMA chunk
+ * elements. Segments are then coalesced when registered, if possible
+ * within the selected memreg mode.
+ *
+ * Note, this routine is never called if the connection's memory
+ * registration strategy is 0 (bounce buffers).
+ */
+
+static int
+rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, int pos,
+        enum rpcrdma_chunktype type, struct rpcrdma_mr_seg *seg, int nsegs)
+{
+        int len, n = 0, p;
+
+        if (pos == 0 && xdrbuf->head[0].iov_len) {
+                seg[n].mr_page = NULL;
+                seg[n].mr_offset = xdrbuf->head[0].iov_base;
+                seg[n].mr_len = xdrbuf->head[0].iov_len;
+                pos += xdrbuf->head[0].iov_len;
+                ++n;
+        }
+
+        if (xdrbuf->page_len && (xdrbuf->pages[0] != NULL)) {
+                if (n == nsegs)
+                        return 0;
+                seg[n].mr_page = xdrbuf->pages[0];
+                seg[n].mr_offset = (void *)(unsigned long) xdrbuf->page_base;
+                seg[n].mr_len = min_t(u32,
+                        PAGE_SIZE - xdrbuf->page_base, xdrbuf->page_len);
+                len = xdrbuf->page_len - seg[n].mr_len;
+                pos += len;
+                ++n;
+                p = 1;
+                while (len > 0) {
+                        if (n == nsegs)
+                                return 0;
+                        seg[n].mr_page = xdrbuf->pages[p];
+                        seg[n].mr_offset = NULL;
+                        seg[n].mr_len = min_t(u32, PAGE_SIZE, len);
+                        len -= seg[n].mr_len;
+                        ++n;
+                        ++p;
+                }
+        }
+
+        if (pos < xdrbuf->len && xdrbuf->tail[0].iov_len) {
+                if (n == nsegs)
+                        return 0;
+                seg[n].mr_page = NULL;
+                seg[n].mr_offset = xdrbuf->tail[0].iov_base;
+                seg[n].mr_len = xdrbuf->tail[0].iov_len;
+                pos += xdrbuf->tail[0].iov_len;
+                ++n;
+        }
+
+        if (pos < xdrbuf->len)
+                dprintk("RPC:       %s: marshaled only %d of %d\n",
+                                __func__, pos, xdrbuf->len);
+
+        return n;
+}
+
+/*
+ * Create read/write chunk lists, and reply chunks, for RDMA
+ *
+ *   Assume check against THRESHOLD has been done, and chunks are required.
+ *   Assume only encoding one list entry for read|write chunks. The NFSv3
+ *     protocol is simple enough to allow this as it only has a single "bulk
+ *     result" in each procedure - complicated NFSv4 COMPOUNDs are not. (The
+ *     RDMA/Sessions NFSv4 proposal addresses this for future v4 revs.)
+ *
+ * When used for a single reply chunk (which is a special write
+ * chunk used for the entire reply, rather than just the data), it
+ * is used primarily for READDIR and READLINK which would otherwise
+ * be severely size-limited by a small rdma inline read max. The server
+ * response will come back as an RDMA Write, followed by a message
+ * of type RDMA_NOMSG carrying the xid and length. As a result, reply
+ * chunks do not provide data alignment, however they do not require
+ * "fixup" (moving the response to the upper layer buffer) either.
+ *
+ * Encoding key for single-list chunks (HLOO = Handle32 Length32 Offset64):
+ *
+ *  Read chunklist (a linked list):
+ *   N elements, position P (same P for all chunks of same arg!):
+ *    1 - PHLOO - 1 - PHLOO - ... - 1 - PHLOO - 0
+ *
+ *  Write chunklist (a list of (one) counted array):
+ *   N elements:
+ *    1 - N - HLOO - HLOO - ... - HLOO - 0
+ *
+ *  Reply chunk (a counted array):
+ *   N elements:
+ *    1 - N - HLOO - HLOO - ... - HLOO
+ */
+
+static unsigned int
+rpcrdma_create_chunks(struct rpc_rqst *rqst, struct xdr_buf *target,
+                struct rpcrdma_msg *headerp, enum rpcrdma_chunktype type)
+{
+        struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
+        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_task->tk_xprt);
+        int nsegs, nchunks = 0;
+        int pos;
+        struct rpcrdma_mr_seg *seg = req->rl_segments;
+        struct rpcrdma_read_chunk *cur_rchunk = NULL;
+        struct rpcrdma_write_array *warray = NULL;
+        struct rpcrdma_write_chunk *cur_wchunk = NULL;
+        u32 *iptr = headerp->rm_body.rm_chunks;
+
+        if (type == rpcrdma_readch || type == rpcrdma_areadch) {
+                /* a read chunk - server will RDMA Read our memory */
+                cur_rchunk = (struct rpcrdma_read_chunk *) iptr;
+        } else {
+                /* a write or reply chunk - server will RDMA Write our memory */
+                *iptr++ = xdr_zero;     /* encode a NULL read chunk list */
+                if (type == rpcrdma_replych)
+                        *iptr++ = xdr_zero;     /* a NULL write chunk list */
+                warray = (struct rpcrdma_write_array *) iptr;
+                cur_wchunk = (struct rpcrdma_write_chunk *) (warray + 1);
+        }
+
+        if (type == rpcrdma_replych || type == rpcrdma_areadch)
+                pos = 0;
+        else
+                pos = target->head[0].iov_len;
+
+        nsegs = rpcrdma_convert_iovs(target, pos, type, seg, RPCRDMA_MAX_SEGS);
+        if (nsegs == 0)
+                return 0;
+
+        do {
+                /* bind/register the memory, then build chunk from result. */
+                int n = rpcrdma_register_external(seg, nsegs,
+                                                cur_wchunk != NULL, r_xprt);
+                if (n <= 0)
+                        goto out;
+                if (cur_rchunk) {       /* read */
+                        cur_rchunk->rc_discrim = xdr_one;
+                        /* all read chunks have the same "position" */
+                        cur_rchunk->rc_position = htonl(pos);
+                        cur_rchunk->rc_target.rs_handle = htonl(seg->mr_rkey);
+                        cur_rchunk->rc_target.rs_length = htonl(seg->mr_len);
+                        xdr_encode_hyper(
+                                        (u32 *)&cur_rchunk->rc_target.rs_offset,
+                                        seg->mr_base);
+                        dprintk("RPC:       %s: read chunk "
+                                "elem %d@0x%llx:0x%x pos %d (%s)\n", __func__,
+                                seg->mr_len, seg->mr_base, seg->mr_rkey, pos,
+                                n < nsegs ? "more" : "last");
+                        cur_rchunk++;
+                        r_xprt->rx_stats.read_chunk_count++;
+                } else {                /* write/reply */
+                        cur_wchunk->wc_target.rs_handle = htonl(seg->mr_rkey);
+                        cur_wchunk->wc_target.rs_length = htonl(seg->mr_len);
+                        xdr_encode_hyper(
+                                        (u32 *)&cur_wchunk->wc_target.rs_offset,
+                                        seg->mr_base);
+                        dprintk("RPC:       %s: %s chunk "
+                                "elem %d@0x%llx:0x%x (%s)\n", __func__,
+                                (type == rpcrdma_replych) ? "reply" : "write",
+                                seg->mr_len, seg->mr_base, seg->mr_rkey,
+                                n < nsegs ? "more" : "last");
+                        cur_wchunk++;
+                        if (type == rpcrdma_replych)
+                                r_xprt->rx_stats.reply_chunk_count++;
+                        else
+                                r_xprt->rx_stats.write_chunk_count++;
+                        r_xprt->rx_stats.total_rdma_request += seg->mr_len;
+                }
+                nchunks++;
+                seg   += n;
+                nsegs -= n;
+        } while (nsegs);
+
+        /* success. all failures return above */
+        req->rl_nchunks = nchunks;
+
+        BUG_ON(nchunks == 0);
+
+        /*
+         * finish off header. If write, marshal discrim and nchunks.
+         */
+        if (cur_rchunk) {
+                iptr = (u32 *) cur_rchunk;
+                *iptr++ = xdr_zero;     /* finish the read chunk list */
+                *iptr++ = xdr_zero;     /* encode a NULL write chunk list */
+                *iptr++ = xdr_zero;     /* encode a NULL reply chunk */
+        } else {
+                warray->wc_discrim = xdr_one;
+                warray->wc_nchunks = htonl(nchunks);
+                iptr = (u32 *) cur_wchunk;
+                if (type == rpcrdma_writech) {
+                        *iptr++ = xdr_zero; /* finish the write chunk list */
+                        *iptr++ = xdr_zero; /* encode a NULL reply chunk */
+                }
+        }
+
+        /*
+         * Return header size.
+         */
+        return (unsigned char *)iptr - (unsigned char *)headerp;
+
+out:
+        for (pos = 0; nchunks--;)
+                pos += rpcrdma_deregister_external(
+                                &req->rl_segments[pos], r_xprt, NULL);
+        return 0;
+}
+
+/*
+ * Copy write data inline.
+ * This function is used for "small" requests. Data which is passed
+ * to RPC via iovecs (or page list) is copied directly into the
+ * pre-registered memory buffer for this request. For small amounts
+ * of data, this is efficient. The cutoff value is tunable.
+ */
+static int
+rpcrdma_inline_pullup(struct rpc_rqst *rqst, int pad)
+{
+        int i, npages, curlen;
+        int copy_len;
+        unsigned char *srcp, *destp;
+        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt);
+
+        destp = rqst->rq_svec[0].iov_base;
+        curlen = rqst->rq_svec[0].iov_len;
+        destp += curlen;
+        /*
+         * Do optional padding where it makes sense. Alignment of write
+         * payload can help the server, if our setting is accurate.
+         */
+        pad -= (curlen + 36/*sizeof(struct rpcrdma_msg_padded)*/);
+        if (pad < 0 || rqst->rq_slen - curlen < RPCRDMA_INLINE_PAD_THRESH)
+                pad = 0;        /* don't pad this request */
+
+        dprintk("RPC:       %s: pad %d destp 0x%p len %d hdrlen %d\n",
+                __func__, pad, destp, rqst->rq_slen, curlen);
+
+        copy_len = rqst->rq_snd_buf.page_len;
+        r_xprt->rx_stats.pullup_copy_count += copy_len;
+        npages = PAGE_ALIGN(rqst->rq_snd_buf.page_base+copy_len) >> PAGE_SHIFT;
+        for (i = 0; copy_len && i < npages; i++) {
+                if (i == 0)
+                        curlen = PAGE_SIZE - rqst->rq_snd_buf.page_base;
+                else
+                        curlen = PAGE_SIZE;
+                if (curlen > copy_len)
+                        curlen = copy_len;
+                dprintk("RPC:       %s: page %d destp 0x%p len %d curlen %d\n",
+                        __func__, i, destp, copy_len, curlen);
+                srcp = kmap_atomic(rqst->rq_snd_buf.pages[i],
+                                        KM_SKB_SUNRPC_DATA);
+                if (i == 0)
+                        memcpy(destp, srcp+rqst->rq_snd_buf.page_base, curlen);
+                else
+                        memcpy(destp, srcp, curlen);
+                kunmap_atomic(srcp, KM_SKB_SUNRPC_DATA);
+                rqst->rq_svec[0].iov_len += curlen;
+                destp += curlen;
+                copy_len -= curlen;
+        }
+        if (rqst->rq_snd_buf.tail[0].iov_len) {
+                curlen = rqst->rq_snd_buf.tail[0].iov_len;
+                if (destp != rqst->rq_snd_buf.tail[0].iov_base) {
+                        memcpy(destp,
+                                rqst->rq_snd_buf.tail[0].iov_base, curlen);
+                        r_xprt->rx_stats.pullup_copy_count += curlen;
+                }
+                dprintk("RPC:       %s: tail destp 0x%p len %d curlen %d\n",
+                        __func__, destp, copy_len, curlen);
+                rqst->rq_svec[0].iov_len += curlen;
+        }
+        /* header now contains entire send message */
+        return pad;
+}
+
+/*
+ * Marshal a request: the primary job of this routine is to choose
+ * the transfer modes. See comments below.
+ *
+ * Uses multiple RDMA IOVs for a request:
+ *  [0] -- RPC RDMA header, which uses memory from the *start* of the
+ *         preregistered buffer that already holds the RPC data in
+ *         its middle.
+ *  [1] -- the RPC header/data, marshaled by RPC and the NFS protocol.
+ *  [2] -- optional padding.
+ *  [3] -- if padded, header only in [1] and data here.
+ */
+
+int
+rpcrdma_marshal_req(struct rpc_rqst *rqst)
+{
+        struct rpc_xprt *xprt = rqst->rq_task->tk_xprt;
+        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
+        struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
+        char *base;
+        size_t hdrlen, rpclen, padlen;
+        enum rpcrdma_chunktype rtype, wtype;
+        struct rpcrdma_msg *headerp;
+
+        /*
+         * rpclen gets amount of data in first buffer, which is the
+         * pre-registered buffer.
+         */
+        base = rqst->rq_svec[0].iov_base;
+        rpclen = rqst->rq_svec[0].iov_len;
+
+        /* build RDMA header in private area at front */
+        headerp = (struct rpcrdma_msg *) req->rl_base;
+        /* don't htonl XID, it's already done in request */
+        headerp->rm_xid = rqst->rq_xid;
+        headerp->rm_vers = xdr_one;
+        headerp->rm_credit = htonl(r_xprt->rx_buf.rb_max_requests);
+        headerp->rm_type = __constant_htonl(RDMA_MSG);
+
+        /*
+         * Chunks needed for results?
+         *
+         * o If the expected result is under the inline threshold, all ops
+         *   return as inline (but see later).
+         * o Large non-read ops return as a single reply chunk.
+         * o Large read ops return data as write chunk(s), header as inline.
+         *
+         * Note: the NFS code sending down multiple result segments implies
+         * the op is one of read, readdir[plus], readlink or NFSv4 getacl.
+         */
+
+        /*
+         * This code can handle read chunks, write chunks OR reply
+         * chunks -- only one type. If the request is too big to fit
+         * inline, then we will choose read chunks. If the request is
+         * a READ, then use write chunks to separate the file data
+         * into pages; otherwise use reply chunks.
+         */
+        if (rqst->rq_rcv_buf.buflen <= RPCRDMA_INLINE_READ_THRESHOLD(rqst))
+                wtype = rpcrdma_noch;
+        else if (rqst->rq_rcv_buf.page_len == 0)
+                wtype = rpcrdma_replych;
+        else if (rqst->rq_rcv_buf.flags & XDRBUF_READ)
+                wtype = rpcrdma_writech;
+        else
+                wtype = rpcrdma_replych;
+
+        /*
+         * Chunks needed for arguments?
+         *
+         * o If the total request is under the inline threshold, all ops
+         *   are sent as inline.
+         * o Large non-write ops are sent with the entire message as a
+         *   single read chunk (protocol 0-position special case).
+         * o Large write ops transmit data as read chunk(s), header as
+         *   inline.
+         *
+         * Note: the NFS code sending down multiple argument segments
+         * implies the op is a write.
+         * TBD check NFSv4 setacl
+         */
+        if (rqst->rq_snd_buf.len <= RPCRDMA_INLINE_WRITE_THRESHOLD(rqst))
+                rtype = rpcrdma_noch;
+        else if (rqst->rq_snd_buf.page_len == 0)
+                rtype = rpcrdma_areadch;
+        else
+                rtype = rpcrdma_readch;
+
+        /* The following simplification is not true forever */
+        if (rtype != rpcrdma_noch && wtype == rpcrdma_replych)
+                wtype = rpcrdma_noch;
+        BUG_ON(rtype != rpcrdma_noch && wtype != rpcrdma_noch);
+
+        if (r_xprt->rx_ia.ri_memreg_strategy == RPCRDMA_BOUNCEBUFFERS &&
+            (rtype != rpcrdma_noch || wtype != rpcrdma_noch)) {
+                /* forced to "pure inline"? */
+                dprintk("RPC:       %s: too much data (%d/%d) for inline\n",
+                        __func__, rqst->rq_rcv_buf.len, rqst->rq_snd_buf.len);
+                return -1;
+        }
+
+        hdrlen = 28; /*sizeof *headerp;*/
+        padlen = 0;
+
+        /*
+         * Pull up any extra send data into the preregistered buffer.
+         * When padding is in use and applies to the transfer, insert
+         * it and change the message type.
+         */
+        if (rtype == rpcrdma_noch) {
+
+                padlen = rpcrdma_inline_pullup(rqst,
+                                                RPCRDMA_INLINE_PAD_VALUE(rqst));
+
+                if (padlen) {
+                        headerp->rm_type = __constant_htonl(RDMA_MSGP);
+                        headerp->rm_body.rm_padded.rm_align =
+                                htonl(RPCRDMA_INLINE_PAD_VALUE(rqst));
+                        headerp->rm_body.rm_padded.rm_thresh =
+                                __constant_htonl(RPCRDMA_INLINE_PAD_THRESH);
+                        headerp->rm_body.rm_padded.rm_pempty[0] = xdr_zero;
+                        headerp->rm_body.rm_padded.rm_pempty[1] = xdr_zero;
+                        headerp->rm_body.rm_padded.rm_pempty[2] = xdr_zero;
+                        hdrlen += 2 * sizeof(u32); /* extra words in padhdr */
+                        BUG_ON(wtype != rpcrdma_noch);
+
+                } else {
+                        headerp->rm_body.rm_nochunks.rm_empty[0] = xdr_zero;
+                        headerp->rm_body.rm_nochunks.rm_empty[1] = xdr_zero;
+                        headerp->rm_body.rm_nochunks.rm_empty[2] = xdr_zero;
+                        /* new length after pullup */
+                        rpclen = rqst->rq_svec[0].iov_len;
+                        /*
+                         * Currently we try to not actually use read inline.
+                         * Reply chunks have the desirable property that
+                         * they land, packed, directly in the target buffers
+                         * without headers, so they require no fixup. The
+                         * additional RDMA Write op sends the same amount
+                         * of data, streams on-the-wire and adds no overhead
+                         * on receive. Therefore, we request a reply chunk
+                         * for non-writes wherever feasible and efficient.
+                         */
+                        if (wtype == rpcrdma_noch &&
+                            r_xprt->rx_ia.ri_memreg_strategy > RPCRDMA_REGISTER)
+                                wtype = rpcrdma_replych;
+                }
+        }
+
+        /*
+         * Marshal chunks. This routine will return the header length
+         * consumed by marshaling.
+         */
+        if (rtype != rpcrdma_noch) {
+                hdrlen = rpcrdma_create_chunks(rqst,
+                                        &rqst->rq_snd_buf, headerp, rtype);
+                wtype = rtype;  /* simplify dprintk */
+
+        } else if (wtype != rpcrdma_noch) {
+                hdrlen = rpcrdma_create_chunks(rqst,
+                                        &rqst->rq_rcv_buf, headerp, wtype);
+        }
+
+        if (hdrlen == 0)
+                return -1;
+
+        dprintk("RPC:       %s: %s: hdrlen %zd rpclen %zd padlen %zd\n"
+                "                   headerp 0x%p base 0x%p lkey 0x%x\n",
+                __func__, transfertypes[wtype], hdrlen, rpclen, padlen,
+                headerp, base, req->rl_iov.lkey);
+
+        /*
+         * initialize send_iov's - normally only two: rdma chunk header and
+         * single preregistered RPC header buffer, but if padding is present,
+         * then use a preregistered (and zeroed) pad buffer between the RPC
+         * header and any write data. In all non-rdma cases, any following
+         * data has been copied into the RPC header buffer.
+         */
+        req->rl_send_iov[0].addr = req->rl_iov.addr;
+        req->rl_send_iov[0].length = hdrlen;
+        req->rl_send_iov[0].lkey = req->rl_iov.lkey;
+
+        req->rl_send_iov[1].addr = req->rl_iov.addr + (base - req->rl_base);
+        req->rl_send_iov[1].length = rpclen;
+        req->rl_send_iov[1].lkey = req->rl_iov.lkey;
+
+        req->rl_niovs = 2;
+
+        if (padlen) {
+                struct rpcrdma_ep *ep = &r_xprt->rx_ep;
+
+                req->rl_send_iov[2].addr = ep->rep_pad.addr;
+                req->rl_send_iov[2].length = padlen;
+                req->rl_send_iov[2].lkey = ep->rep_pad.lkey;
+
+                req->rl_send_iov[3].addr = req->rl_send_iov[1].addr + rpclen;
+                req->rl_send_iov[3].length = rqst->rq_slen - rpclen;
+                req->rl_send_iov[3].lkey = req->rl_iov.lkey;
+
+                req->rl_niovs = 4;
+        }
+
+        return 0;
+}
+
+/*
+ * Chase down a received write or reply chunklist to get length
+ * RDMA'd by server. See map at rpcrdma_create_chunks()! :-)
+ */
+static int
+rpcrdma_count_chunks(struct rpcrdma_rep *rep, int max, int wrchunk, u32 **iptrp)
+{
+        unsigned int i, total_len;
+        struct rpcrdma_write_chunk *cur_wchunk;
+
+        i = ntohl(**iptrp);     /* get array count */
+        if (i > max)
+                return -1;
+        cur_wchunk = (struct rpcrdma_write_chunk *) (*iptrp + 1);
+        total_len = 0;
+        while (i--) {
+                struct rpcrdma_segment *seg = &cur_wchunk->wc_target;
+                ifdebug(FACILITY) {
+                        u64 off;
+                        xdr_decode_hyper((u32 *)&seg->rs_offset, &off);
+                        dprintk("RPC:       %s: chunk %d@0x%llx:0x%x\n",
+                                __func__,
+                                ntohl(seg->rs_length),
+                                off,
+                                ntohl(seg->rs_handle));
+                }
+                total_len += ntohl(seg->rs_length);
+                ++cur_wchunk;
+        }
+        /* check and adjust for properly terminated write chunk */
+        if (wrchunk) {
+                u32 *w = (u32 *) cur_wchunk;
+                if (*w++ != xdr_zero)
+                        return -1;
+                cur_wchunk = (struct rpcrdma_write_chunk *) w;
+        }
+        if ((char *) cur_wchunk > rep->rr_base + rep->rr_len)
+                return -1;
+
+        *iptrp = (u32 *) cur_wchunk;
+        return total_len;
+}
+
+/*
+ * Scatter inline received data back into provided iov's.
+ */
+static void
+rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len)
+{
+        int i, npages, curlen, olen;
+        char *destp;
+
+        curlen = rqst->rq_rcv_buf.head[0].iov_len;
+        if (curlen > copy_len) {        /* write chunk header fixup */
+                curlen = copy_len;
+                rqst->rq_rcv_buf.head[0].iov_len = curlen;
+        }
+
+        dprintk("RPC:       %s: srcp 0x%p len %d hdrlen %d\n",
+                __func__, srcp, copy_len, curlen);
+
+        /* Shift pointer for first receive segment only */
+        rqst->rq_rcv_buf.head[0].iov_base = srcp;
+        srcp += curlen;
+        copy_len -= curlen;
+
+        olen = copy_len;
+        i = 0;
+        rpcx_to_rdmax(rqst->rq_xprt)->rx_stats.fixup_copy_count += olen;
+        if (copy_len && rqst->rq_rcv_buf.page_len) {
+                npages = PAGE_ALIGN(rqst->rq_rcv_buf.page_base +
+                        rqst->rq_rcv_buf.page_len) >> PAGE_SHIFT;
+                for (; i < npages; i++) {
+                        if (i == 0)
+                                curlen = PAGE_SIZE - rqst->rq_rcv_buf.page_base;
+                        else
+                                curlen = PAGE_SIZE;
+                        if (curlen > copy_len)
+                                curlen = copy_len;
+                        dprintk("RPC:       %s: page %d"
+                                " srcp 0x%p len %d curlen %d\n",
+                                __func__, i, srcp, copy_len, curlen);
+                        destp = kmap_atomic(rqst->rq_rcv_buf.pages[i],
+                                                KM_SKB_SUNRPC_DATA);
+                        if (i == 0)
+                                memcpy(destp + rqst->rq_rcv_buf.page_base,
+                                                srcp, curlen);
+                        else
+                                memcpy(destp, srcp, curlen);
+                        flush_dcache_page(rqst->rq_rcv_buf.pages[i]);
+                        kunmap_atomic(destp, KM_SKB_SUNRPC_DATA);
+                        srcp += curlen;
+                        copy_len -= curlen;
+                        if (copy_len == 0)
+                                break;
+                }
+                rqst->rq_rcv_buf.page_len = olen - copy_len;
+        } else
+                rqst->rq_rcv_buf.page_len = 0;
+
+        if (copy_len && rqst->rq_rcv_buf.tail[0].iov_len) {
+                curlen = copy_len;
+                if (curlen > rqst->rq_rcv_buf.tail[0].iov_len)
+                        curlen = rqst->rq_rcv_buf.tail[0].iov_len;
+                if (rqst->rq_rcv_buf.tail[0].iov_base != srcp)
+                        memcpy(rqst->rq_rcv_buf.tail[0].iov_base, srcp, curlen);
+                dprintk("RPC:       %s: tail srcp 0x%p len %d curlen %d\n",
+                        __func__, srcp, copy_len, curlen);
+                rqst->rq_rcv_buf.tail[0].iov_len = curlen;
+                copy_len -= curlen; ++i;
+        } else
+                rqst->rq_rcv_buf.tail[0].iov_len = 0;
+
+        if (copy_len)
+                dprintk("RPC:       %s: %d bytes in"
+                        " %d extra segments (%d lost)\n",
+                        __func__, olen, i, copy_len);
+
+        /* TBD avoid a warning from call_decode() */
+        rqst->rq_private_buf = rqst->rq_rcv_buf;
+}
+
+/*
+ * This function is called when an async event is posted to
+ * the connection which changes the connection state. All it
+ * does at this point is mark the connection up/down, the rpc
+ * timers do the rest.
+ */
+void
+rpcrdma_conn_func(struct rpcrdma_ep *ep)
+{
+        struct rpc_xprt *xprt = ep->rep_xprt;
+
+        spin_lock_bh(&xprt->transport_lock);
+        if (ep->rep_connected > 0) {
+                if (!xprt_test_and_set_connected(xprt))
+                        xprt_wake_pending_tasks(xprt, 0);
+        } else {
+                if (xprt_test_and_clear_connected(xprt))
+                        xprt_wake_pending_tasks(xprt, ep->rep_connected);
+        }
+        spin_unlock_bh(&xprt->transport_lock);
+}
+
+/*
+ * This function is called when memory window unbind which we are waiting
+ * for completes. Just use rr_func (zeroed by upcall) to signal completion.
+ */
+static void
+rpcrdma_unbind_func(struct rpcrdma_rep *rep)
+{
+        wake_up(&rep->rr_unbind);
+}
+
+/*
+ * Called as a tasklet to do req/reply match and complete a request
+ * Errors must result in the RPC task either being awakened, or
+ * allowed to timeout, to discover the errors at that time.
+ */
+void
+rpcrdma_reply_handler(struct rpcrdma_rep *rep)
+{
+        struct rpcrdma_msg *headerp;
+        struct rpcrdma_req *req;
+        struct rpc_rqst *rqst;
+        struct rpc_xprt *xprt = rep->rr_xprt;
+        struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
+        u32 *iptr;
+        int i, rdmalen, status;
+
+        /* Check status. If bad, signal disconnect and return rep to pool */
+        if (rep->rr_len == ~0U) {
+                rpcrdma_recv_buffer_put(rep);
+                if (r_xprt->rx_ep.rep_connected == 1) {
+                        r_xprt->rx_ep.rep_connected = -EIO;
+                        rpcrdma_conn_func(&r_xprt->rx_ep);
+                }
+                return;
+        }
+        if (rep->rr_len < 28) {
+                dprintk("RPC:       %s: short/invalid reply\n", __func__);
+                goto repost;
+        }
+        headerp = (struct rpcrdma_msg *) rep->rr_base;
+        if (headerp->rm_vers != xdr_one) {
+                dprintk("RPC:       %s: invalid version %d\n",
+                        __func__, ntohl(headerp->rm_vers));
+                goto repost;
+        }
+
+        /* Get XID and try for a match. */
+        spin_lock(&xprt->transport_lock);
+        rqst = xprt_lookup_rqst(xprt, headerp->rm_xid);
+        if (rqst == NULL) {
+                spin_unlock(&xprt->transport_lock);
+                dprintk("RPC:       %s: reply 0x%p failed "
+                        "to match any request xid 0x%08x len %d\n",
+                        __func__, rep, headerp->rm_xid, rep->rr_len);
+repost:
+                r_xprt->rx_stats.bad_reply_count++;
+                rep->rr_func = rpcrdma_reply_handler;
+                if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, &r_xprt->rx_ep, rep))
+                        rpcrdma_recv_buffer_put(rep);
+
+                return;
+        }
+
+        /* get request object */
+        req = rpcr_to_rdmar(rqst);
+
+        dprintk("RPC:       %s: reply 0x%p completes request 0x%p\n"
+                "                   RPC request 0x%p xid 0x%08x\n",
+                        __func__, rep, req, rqst, headerp->rm_xid);
+
+        BUG_ON(!req || req->rl_reply);
+
+        /* from here on, the reply is no longer an orphan */
+        req->rl_reply = rep;
+
+        /* check for expected message types */
+        /* The order of some of these tests is important. */
+        switch (headerp->rm_type) {
+        case __constant_htonl(RDMA_MSG):
+                /* never expect read chunks */
+                /* never expect reply chunks (two ways to check) */
+                /* never expect write chunks without having offered RDMA */
+                if (headerp->rm_body.rm_chunks[0] != xdr_zero ||
+                    (headerp->rm_body.rm_chunks[1] == xdr_zero &&
+                     headerp->rm_body.rm_chunks[2] != xdr_zero) ||
+                    (headerp->rm_body.rm_chunks[1] != xdr_zero &&
+                     req->rl_nchunks == 0))
+                        goto badheader;
+                if (headerp->rm_body.rm_chunks[1] != xdr_zero) {
+                        /* count any expected write chunks in read reply */
+                        /* start at write chunk array count */
+                        iptr = &headerp->rm_body.rm_chunks[2];
+                        rdmalen = rpcrdma_count_chunks(rep,
+                                                req->rl_nchunks, 1, &iptr);
+                        /* check for validity, and no reply chunk after */
+                        if (rdmalen < 0 || *iptr++ != xdr_zero)
+                                goto badheader;
+                        rep->rr_len -=
+                            ((unsigned char *)iptr - (unsigned char *)headerp);
+                        status = rep->rr_len + rdmalen;
+                        r_xprt->rx_stats.total_rdma_reply += rdmalen;
+                } else {
+                        /* else ordinary inline */
+                        iptr = (u32 *)((unsigned char *)headerp + 28);
+                        rep->rr_len -= 28; /*sizeof *headerp;*/
+                        status = rep->rr_len;
+                }
+                /* Fix up the rpc results for upper layer */
+                rpcrdma_inline_fixup(rqst, (char *)iptr, rep->rr_len);
+                break;
+
+        case __constant_htonl(RDMA_NOMSG):
+                /* never expect read or write chunks, always reply chunks */
+                if (headerp->rm_body.rm_chunks[0] != xdr_zero ||
+                    headerp->rm_body.rm_chunks[1] != xdr_zero ||
+                    headerp->rm_body.rm_chunks[2] != xdr_one ||
+                    req->rl_nchunks == 0)
+                        goto badheader;
+                iptr = (u32 *)((unsigned char *)headerp + 28);
+                rdmalen = rpcrdma_count_chunks(rep, req->rl_nchunks, 0, &iptr);
+                if (rdmalen < 0)
+                        goto badheader;
+                r_xprt->rx_stats.total_rdma_reply += rdmalen;
+                /* Reply chunk buffer already is the reply vector - no fixup. */
+                status = rdmalen;
+                break;
+
+badheader:
+        default:
+                dprintk("%s: invalid rpcrdma reply header (type %d):"
+                                " chunks[012] == %d %d %d"
+                                " expected chunks <= %d\n",
+                                __func__, ntohl(headerp->rm_type),
+                                headerp->rm_body.rm_chunks[0],
+                                headerp->rm_body.rm_chunks[1],
+                                headerp->rm_body.rm_chunks[2],
+                                req->rl_nchunks);
+                status = -EIO;
+                r_xprt->rx_stats.bad_reply_count++;
+                break;
+        }
+
+        /* If using mw bind, start the deregister process now. */
+        /* (Note: if mr_free(), cannot perform it here, in tasklet context) */
+        if (req->rl_nchunks) switch (r_xprt->rx_ia.ri_memreg_strategy) {
+        case RPCRDMA_MEMWINDOWS:
+                for (i = 0; req->rl_nchunks-- > 1;)
+                        i += rpcrdma_deregister_external(
+                                &req->rl_segments[i], r_xprt, NULL);
+                /* Optionally wait (not here) for unbinds to complete */
+                rep->rr_func = rpcrdma_unbind_func;
+                (void) rpcrdma_deregister_external(&req->rl_segments[i],
+                                                   r_xprt, rep);
+                break;
+        case RPCRDMA_MEMWINDOWS_ASYNC:
+                for (i = 0; req->rl_nchunks--;)
+                        i += rpcrdma_deregister_external(&req->rl_segments[i],
+                                                         r_xprt, NULL);
+                break;
+        default:
+                break;
+        }
+
+        dprintk("RPC:       %s: xprt_complete_rqst(0x%p, 0x%p, %d)\n",
+                        __func__, xprt, rqst, status);
+        xprt_complete_rqst(rqst->rq_task, status);
+        spin_unlock(&xprt->transport_lock);
+}