rdma: SVCRDMA sendto

/*

 * Copyright (c) 2005-2006 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.

 *

 * Author: Tom Tucker <tom@opengridcomputing.com>

 */

#include <linux/sunrpc/debug.h>

#include <linux/sunrpc/rpc_rdma.h>

#include <linux/spinlock.h>

#include <asm/unaligned.h>

#include <rdma/ib_verbs.h>

#include <rdma/rdma_cm.h>

#include <linux/sunrpc/svc_rdma.h>

#define RPCDBG_FACILITY	RPCDBG_SVCXPRT

/* Encode an XDR as an array of IB SGE

 *

 * Assumptions:

 * - head[0] is physically contiguous.

 * - tail[0] is physically contiguous.

 * - pages[] is not physically or virtually contigous and consists of

 *   PAGE_SIZE elements.

 *

 * Output:

 * SGE[0]              reserved for RCPRDMA header

 * SGE[1]              data from xdr->head[]

 * SGE[2..sge_count-2] data from xdr->pages[]

 * SGE[sge_count-1]    data from xdr->tail.

 *

 */

static struct ib_sge *xdr_to_sge(struct svcxprt_rdma *xprt,

				 struct xdr_buf *xdr,

				 struct ib_sge *sge,

				 int *sge_count)

{

	/* Max we need is the length of the XDR / pagesize + one for

	 * head + one for tail + one for RPCRDMA header

	 */

	int sge_max = (xdr->len+PAGE_SIZE-1) / PAGE_SIZE + 3;

	int sge_no;

	u32 byte_count = xdr->len;

	u32 sge_bytes;

	u32 page_bytes;

	int page_off;

	int page_no;

	/* Skip the first sge, this is for the RPCRDMA header */

	sge_no = 1;

	/* Head SGE */

	sge[sge_no].addr = ib_dma_map_single(xprt->sc_cm_id->device,

					     xdr->head[0].iov_base,

					     xdr->head[0].iov_len,

					     DMA_TO_DEVICE);

	sge_bytes = min_t(u32, byte_count, xdr->head[0].iov_len);

	byte_count -= sge_bytes;

	sge[sge_no].length = sge_bytes;

	sge[sge_no].lkey = xprt->sc_phys_mr->lkey;

	sge_no++;

	/* pages SGE */

	page_no = 0;

	page_bytes = xdr->page_len;

	page_off = xdr->page_base;

	while (byte_count && page_bytes) {

		sge_bytes = min_t(u32, byte_count, (PAGE_SIZE-page_off));

		sge[sge_no].addr =

			ib_dma_map_page(xprt->sc_cm_id->device,

					xdr->pages[page_no], page_off,

					sge_bytes, DMA_TO_DEVICE);

		sge_bytes = min(sge_bytes, page_bytes);

		byte_count -= sge_bytes;

		page_bytes -= sge_bytes;

		sge[sge_no].length = sge_bytes;

		sge[sge_no].lkey = xprt->sc_phys_mr->lkey;

		sge_no++;

		page_no++;

		page_off = 0; /* reset for next time through loop */

	}

	/* Tail SGE */

	if (byte_count && xdr->tail[0].iov_len) {

		sge[sge_no].addr =

			ib_dma_map_single(xprt->sc_cm_id->device,

					  xdr->tail[0].iov_base,

					  xdr->tail[0].iov_len,

					  DMA_TO_DEVICE);

		sge_bytes = min_t(u32, byte_count, xdr->tail[0].iov_len);

		byte_count -= sge_bytes;

		sge[sge_no].length = sge_bytes;

		sge[sge_no].lkey = xprt->sc_phys_mr->lkey;

		sge_no++;

	}

	BUG_ON(sge_no > sge_max);

	BUG_ON(byte_count != 0);

	*sge_count = sge_no;

	return sge;

}

/* Assumptions:

 * - The specified write_len can be represented in sc_max_sge * PAGE_SIZE

 */

static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,

		      u32 rmr, u64 to,

		      u32 xdr_off, int write_len,

		      struct ib_sge *xdr_sge, int sge_count)

{

	struct svc_rdma_op_ctxt *tmp_sge_ctxt;

	struct ib_send_wr write_wr;

	struct ib_sge *sge;

	int xdr_sge_no;

	int sge_no;

	int sge_bytes;

	int sge_off;

	int bc;

	struct svc_rdma_op_ctxt *ctxt;

	int ret = 0;

	BUG_ON(sge_count >= 32);

	dprintk("svcrdma: RDMA_WRITE rmr=%x, to=%llx, xdr_off=%d, "

		"write_len=%d, xdr_sge=%p, sge_count=%d\n",

		rmr, to, xdr_off, write_len, xdr_sge, sge_count);

	ctxt = svc_rdma_get_context(xprt);

	ctxt->count = 0;

	tmp_sge_ctxt = svc_rdma_get_context(xprt);

	sge = tmp_sge_ctxt->sge;

	/* Find the SGE associated with xdr_off */

	for (bc = xdr_off, xdr_sge_no = 1; bc && xdr_sge_no < sge_count;

	     xdr_sge_no++) {

		if (xdr_sge[xdr_sge_no].length > bc)

			break;

		bc -= xdr_sge[xdr_sge_no].length;

	}

	sge_off = bc;

	bc = write_len;

	sge_no = 0;

	/* Copy the remaining SGE */

	while (bc != 0 && xdr_sge_no < sge_count) {

		sge[sge_no].addr = xdr_sge[xdr_sge_no].addr + sge_off;

		sge[sge_no].lkey = xdr_sge[xdr_sge_no].lkey;

		sge_bytes = min((size_t)bc,

				(size_t)(xdr_sge[xdr_sge_no].length-sge_off));

		sge[sge_no].length = sge_bytes;

		sge_off = 0;

		sge_no++;

		xdr_sge_no++;

		bc -= sge_bytes;

	}

	BUG_ON(bc != 0);

	BUG_ON(xdr_sge_no > sge_count);

	/* Prepare WRITE WR */

	memset(&write_wr, 0, sizeof write_wr);

	ctxt->wr_op = IB_WR_RDMA_WRITE;

	write_wr.wr_id = (unsigned long)ctxt;

	write_wr.sg_list = &sge[0];

	write_wr.num_sge = sge_no;

	write_wr.opcode = IB_WR_RDMA_WRITE;

	write_wr.send_flags = IB_SEND_SIGNALED;

	write_wr.wr.rdma.rkey = rmr;

	write_wr.wr.rdma.remote_addr = to;

	/* Post It */

	atomic_inc(&rdma_stat_write);

	if (svc_rdma_send(xprt, &write_wr)) {

		svc_rdma_put_context(ctxt, 1);

		/* Fatal error, close transport */

		ret = -EIO;

	}

	svc_rdma_put_context(tmp_sge_ctxt, 0);

	return ret;

}

static int send_write_chunks(struct svcxprt_rdma *xprt,

			     struct rpcrdma_msg *rdma_argp,

			     struct rpcrdma_msg *rdma_resp,

			     struct svc_rqst *rqstp,

			     struct ib_sge *sge,

			     int sge_count)

{

	u32 xfer_len = rqstp->rq_res.page_len + rqstp->rq_res.tail[0].iov_len;

	int write_len;

	int max_write;

	u32 xdr_off;

	int chunk_off;

	int chunk_no;

	struct rpcrdma_write_array *arg_ary;

	struct rpcrdma_write_array *res_ary;

	int ret;

	arg_ary = svc_rdma_get_write_array(rdma_argp);

	if (!arg_ary)

		return 0;

	res_ary = (struct rpcrdma_write_array *)

		&rdma_resp->rm_body.rm_chunks[1];

	max_write = xprt->sc_max_sge * PAGE_SIZE;

	/* Write chunks start at the pagelist */

	for (xdr_off = rqstp->rq_res.head[0].iov_len, chunk_no = 0;

	     xfer_len && chunk_no < arg_ary->wc_nchunks;

	     chunk_no++) {

		struct rpcrdma_segment *arg_ch;

		u64 rs_offset;

		arg_ch = &arg_ary->wc_array[chunk_no].wc_target;

		write_len = min(xfer_len, arg_ch->rs_length);

		/* Prepare the response chunk given the length actually

		 * written */

		rs_offset = get_unaligned(&(arg_ch->rs_offset));

		svc_rdma_xdr_encode_array_chunk(res_ary, chunk_no,

					    arg_ch->rs_handle,

					    rs_offset,

					    write_len);

		chunk_off = 0;

		while (write_len) {

			int this_write;

			this_write = min(write_len, max_write);

			ret = send_write(xprt, rqstp,

					 arg_ch->rs_handle,

					 rs_offset + chunk_off,

					 xdr_off,

					 this_write,

					 sge,

					 sge_count);

			if (ret) {

				dprintk("svcrdma: RDMA_WRITE failed, ret=%d\n",

					ret);

				return -EIO;

			}

			chunk_off += this_write;

			xdr_off += this_write;

			xfer_len -= this_write;

			write_len -= this_write;

		}

	}

	/* Update the req with the number of chunks actually used */

	svc_rdma_xdr_encode_write_list(rdma_resp, chunk_no);

	return rqstp->rq_res.page_len + rqstp->rq_res.tail[0].iov_len;

}

static int send_reply_chunks(struct svcxprt_rdma *xprt,

			     struct rpcrdma_msg *rdma_argp,

			     struct rpcrdma_msg *rdma_resp,

			     struct svc_rqst *rqstp,

			     struct ib_sge *sge,

			     int sge_count)

{

	u32 xfer_len = rqstp->rq_res.len;

	int write_len;

	int max_write;

	u32 xdr_off;

	int chunk_no;

	int chunk_off;

	struct rpcrdma_segment *ch;

	struct rpcrdma_write_array *arg_ary;

	struct rpcrdma_write_array *res_ary;

	int ret;

	arg_ary = svc_rdma_get_reply_array(rdma_argp);

	if (!arg_ary)

		return 0;

	/* XXX: need to fix when reply lists occur with read-list and or

	 * write-list */

	res_ary = (struct rpcrdma_write_array *)

		&rdma_resp->rm_body.rm_chunks[2];

	max_write = xprt->sc_max_sge * PAGE_SIZE;

	/* xdr offset starts at RPC message */

	for (xdr_off = 0, chunk_no = 0;

	     xfer_len && chunk_no < arg_ary->wc_nchunks;

	     chunk_no++) {

		u64 rs_offset;

		ch = &arg_ary->wc_array[chunk_no].wc_target;

		write_len = min(xfer_len, ch->rs_length);

		/* Prepare the reply chunk given the length actually

		 * written */

		rs_offset = get_unaligned(&(ch->rs_offset));

		svc_rdma_xdr_encode_array_chunk(res_ary, chunk_no,

					    ch->rs_handle, rs_offset,

					    write_len);

		chunk_off = 0;

		while (write_len) {

			int this_write;

			this_write = min(write_len, max_write);

			ret = send_write(xprt, rqstp,

					 ch->rs_handle,

					 rs_offset + chunk_off,

					 xdr_off,

					 this_write,

					 sge,

					 sge_count);

			if (ret) {

				dprintk("svcrdma: RDMA_WRITE failed, ret=%d\n",

					ret);

				return -EIO;

			}

			chunk_off += this_write;

			xdr_off += this_write;

			xfer_len -= this_write;

			write_len -= this_write;

		}

	}

	/* Update the req with the number of chunks actually used */

	svc_rdma_xdr_encode_reply_array(res_ary, chunk_no);

	return rqstp->rq_res.len;

}

/* This function prepares the portion of the RPCRDMA message to be

 * sent in the RDMA_SEND. This function is called after data sent via

 * RDMA has already been transmitted. There are three cases:

 * - The RPCRDMA header, RPC header, and payload are all sent in a

 *   single RDMA_SEND. This is the "inline" case.

 * - The RPCRDMA header and some portion of the RPC header and data

 *   are sent via this RDMA_SEND and another portion of the data is

 *   sent via RDMA.

 * - The RPCRDMA header [NOMSG] is sent in this RDMA_SEND and the RPC

 *   header and data are all transmitted via RDMA.

 * In all three cases, this function prepares the RPCRDMA header in

 * sge[0], the 'type' parameter indicates the type to place in the

 * RPCRDMA header, and the 'byte_count' field indicates how much of

 * the XDR to include in this RDMA_SEND.

 */

static int send_reply(struct svcxprt_rdma *rdma,

		      struct svc_rqst *rqstp,

		      struct page *page,

		      struct rpcrdma_msg *rdma_resp,

		      struct svc_rdma_op_ctxt *ctxt,

		      int sge_count,

		      int byte_count)

{

	struct ib_send_wr send_wr;

	int sge_no;

	int sge_bytes;

	int page_no;

	int ret;

	/* Prepare the context */

	ctxt->pages[0] = page;

	ctxt->count = 1;

	/* Prepare the SGE for the RPCRDMA Header */

	ctxt->sge[0].addr =

		ib_dma_map_page(rdma->sc_cm_id->device,

				page, 0, PAGE_SIZE, DMA_TO_DEVICE);

	ctxt->direction = DMA_TO_DEVICE;

	ctxt->sge[0].length = svc_rdma_xdr_get_reply_hdr_len(rdma_resp);

	ctxt->sge[0].lkey = rdma->sc_phys_mr->lkey;

	/* Determine how many of our SGE are to be transmitted */

	for (sge_no = 1; byte_count && sge_no < sge_count; sge_no++) {

		sge_bytes = min((size_t)ctxt->sge[sge_no].length,

				(size_t)byte_count);

		byte_count -= sge_bytes;

	}

	BUG_ON(byte_count != 0);

	/* Save all respages in the ctxt and remove them from the

	 * respages array. They are our pages until the I/O

	 * completes.

	 */

	for (page_no = 0; page_no < rqstp->rq_resused; page_no++) {

		ctxt->pages[page_no+1] = rqstp->rq_respages[page_no];

		ctxt->count++;

		rqstp->rq_respages[page_no] = NULL;

	}

	BUG_ON(sge_no > rdma->sc_max_sge);

	memset(&send_wr, 0, sizeof send_wr);

	ctxt->wr_op = IB_WR_SEND;

	send_wr.wr_id = (unsigned long)ctxt;

	send_wr.sg_list = ctxt->sge;

	send_wr.num_sge = sge_no;

	send_wr.opcode = IB_WR_SEND;

	send_wr.send_flags =  IB_SEND_SIGNALED;

	ret = svc_rdma_send(rdma, &send_wr);

	if (ret)

		svc_rdma_put_context(ctxt, 1);

	return ret;

}

void svc_rdma_prep_reply_hdr(struct svc_rqst *rqstp)

{

}

/*

 * Return the start of an xdr buffer.

 */

static void *xdr_start(struct xdr_buf *xdr)

{

	return xdr->head[0].iov_base -

		(xdr->len -

		 xdr->page_len -

		 xdr->tail[0].iov_len -

		 xdr->head[0].iov_len);

}

int svc_rdma_sendto(struct svc_rqst *rqstp)

{

	struct svc_xprt *xprt = rqstp->rq_xprt;

	struct svcxprt_rdma *rdma =

		container_of(xprt, struct svcxprt_rdma, sc_xprt);

	struct rpcrdma_msg *rdma_argp;

	struct rpcrdma_msg *rdma_resp;

	struct rpcrdma_write_array *reply_ary;

	enum rpcrdma_proc reply_type;

	int ret;

	int inline_bytes;

	struct ib_sge *sge;

	int sge_count = 0;

	struct page *res_page;

	struct svc_rdma_op_ctxt *ctxt;

	dprintk("svcrdma: sending response for rqstp=%p\n", rqstp);

	/* Get the RDMA request header. */

	rdma_argp = xdr_start(&rqstp->rq_arg);

	/* Build an SGE for the XDR */

	ctxt = svc_rdma_get_context(rdma);

	ctxt->direction = DMA_TO_DEVICE;

	sge = xdr_to_sge(rdma, &rqstp->rq_res, ctxt->sge, &sge_count);

	inline_bytes = rqstp->rq_res.len;

	/* Create the RDMA response header */

	res_page = svc_rdma_get_page();

	rdma_resp = page_address(res_page);

	reply_ary = svc_rdma_get_reply_array(rdma_argp);

	if (reply_ary)

		reply_type = RDMA_NOMSG;

	else

		reply_type = RDMA_MSG;

	svc_rdma_xdr_encode_reply_header(rdma, rdma_argp,

					 rdma_resp, reply_type);

	/* Send any write-chunk data and build resp write-list */

	ret = send_write_chunks(rdma, rdma_argp, rdma_resp,

				rqstp, sge, sge_count);

	if (ret < 0) {

		printk(KERN_ERR "svcrdma: failed to send write chunks, rc=%d\n",

		       ret);

		goto error;

	}

	inline_bytes -= ret;

	/* Send any reply-list data and update resp reply-list */

	ret = send_reply_chunks(rdma, rdma_argp, rdma_resp,

				rqstp, sge, sge_count);

	if (ret < 0) {

		printk(KERN_ERR "svcrdma: failed to send reply chunks, rc=%d\n",

		       ret);

		goto error;

	}

	inline_bytes -= ret;

	ret = send_reply(rdma, rqstp, res_page, rdma_resp, ctxt, sge_count,

			 inline_bytes);

	dprintk("svcrdma: send_reply returns %d\n", ret);

	return ret;

 error:

	svc_rdma_put_context(ctxt, 0);

	put_page(res_page);

	return ret;

}