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linux-sg2042/net/sunrpc/xprtrdma/svc_rdma_sendto.c

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/*
* Copyright (c) 2016 Oracle. All rights reserved.
* Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
* 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>
*/
/* Operation
*
* The main entry point is svc_rdma_sendto. This is called by the
* RPC server when an RPC Reply is ready to be transmitted to a client.
*
* The passed-in svc_rqst contains a struct xdr_buf which holds an
* XDR-encoded RPC Reply message. sendto must construct the RPC-over-RDMA
* transport header, post all Write WRs needed for this Reply, then post
* a Send WR conveying the transport header and the RPC message itself to
* the client.
*
* svc_rdma_sendto must fully transmit the Reply before returning, as
* the svc_rqst will be recycled as soon as sendto returns. Remaining
* resources referred to by the svc_rqst are also recycled at that time.
* Therefore any resources that must remain longer must be detached
* from the svc_rqst and released later.
*
* Page Management
*
* The I/O that performs Reply transmission is asynchronous, and may
* complete well after sendto returns. Thus pages under I/O must be
* removed from the svc_rqst before sendto returns.
*
* The logic here depends on Send Queue and completion ordering. Since
* the Send WR is always posted last, it will always complete last. Thus
* when it completes, it is guaranteed that all previous Write WRs have
* also completed.
*
* Write WRs are constructed and posted. Each Write segment gets its own
* svc_rdma_rw_ctxt, allowing the Write completion handler to find and
* DMA-unmap the pages under I/O for that Write segment. The Write
* completion handler does not release any pages.
*
* When the Send WR is constructed, it also gets its own svc_rdma_op_ctxt.
* The ownership of all of the Reply's pages are transferred into that
* ctxt, the Send WR is posted, and sendto returns.
*
* The svc_rdma_op_ctxt is presented when the Send WR completes. The
* Send completion handler finally releases the Reply's pages.
*
* This mechanism also assumes that completions on the transport's Send
* Completion Queue do not run in parallel. Otherwise a Write completion
* and Send completion running at the same time could release pages that
* are still DMA-mapped.
*
* Error Handling
*
* - If the Send WR is posted successfully, it will either complete
* successfully, or get flushed. Either way, the Send completion
* handler releases the Reply's pages.
* - If the Send WR cannot be not posted, the forward path releases
* the Reply's pages.
*
* This handles the case, without the use of page reference counting,
* where two different Write segments send portions of the same page.
*/
#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
static u32 xdr_padsize(u32 len)
{
return (len & 3) ? (4 - (len & 3)) : 0;
}
/* Returns length of transport header, in bytes.
*/
static unsigned int svc_rdma_reply_hdr_len(__be32 *rdma_resp)
{
unsigned int nsegs;
__be32 *p;
p = rdma_resp;
/* RPC-over-RDMA V1 replies never have a Read list. */
p += rpcrdma_fixed_maxsz + 1;
/* Skip Write list. */
while (*p++ != xdr_zero) {
nsegs = be32_to_cpup(p++);
p += nsegs * rpcrdma_segment_maxsz;
}
/* Skip Reply chunk. */
if (*p++ != xdr_zero) {
nsegs = be32_to_cpup(p++);
p += nsegs * rpcrdma_segment_maxsz;
}
return (unsigned long)p - (unsigned long)rdma_resp;
}
/* One Write chunk is copied from Call transport header to Reply
* transport header. Each segment's length field is updated to
* reflect number of bytes consumed in the segment.
*
* Returns number of segments in this chunk.
*/
static unsigned int xdr_encode_write_chunk(__be32 *dst, __be32 *src,
unsigned int remaining)
{
unsigned int i, nsegs;
u32 seg_len;
/* Write list discriminator */
*dst++ = *src++;
/* number of segments in this chunk */
nsegs = be32_to_cpup(src);
*dst++ = *src++;
for (i = nsegs; i; i--) {
/* segment's RDMA handle */
*dst++ = *src++;
/* bytes returned in this segment */
seg_len = be32_to_cpu(*src);
if (remaining >= seg_len) {
/* entire segment was consumed */
*dst = *src;
remaining -= seg_len;
} else {
/* segment only partly filled */
*dst = cpu_to_be32(remaining);
remaining = 0;
}
dst++; src++;
/* segment's RDMA offset */
*dst++ = *src++;
*dst++ = *src++;
}
return nsegs;
}
/* The client provided a Write list in the Call message. Fill in
* the segments in the first Write chunk in the Reply's transport
* header with the number of bytes consumed in each segment.
* Remaining chunks are returned unused.
*
* Assumptions:
* - Client has provided only one Write chunk
*/
static void svc_rdma_xdr_encode_write_list(__be32 *rdma_resp, __be32 *wr_ch,
unsigned int consumed)
{
unsigned int nsegs;
__be32 *p, *q;
/* RPC-over-RDMA V1 replies never have a Read list. */
p = rdma_resp + rpcrdma_fixed_maxsz + 1;
q = wr_ch;
while (*q != xdr_zero) {
nsegs = xdr_encode_write_chunk(p, q, consumed);
q += 2 + nsegs * rpcrdma_segment_maxsz;
p += 2 + nsegs * rpcrdma_segment_maxsz;
consumed = 0;
}
/* Terminate Write list */
*p++ = xdr_zero;
/* Reply chunk discriminator; may be replaced later */
*p = xdr_zero;
}
/* The client provided a Reply chunk in the Call message. Fill in
* the segments in the Reply chunk in the Reply message with the
* number of bytes consumed in each segment.
*
* Assumptions:
* - Reply can always fit in the provided Reply chunk
*/
static void svc_rdma_xdr_encode_reply_chunk(__be32 *rdma_resp, __be32 *rp_ch,
unsigned int consumed)
{
__be32 *p;
/* Find the Reply chunk in the Reply's xprt header.
* RPC-over-RDMA V1 replies never have a Read list.
*/
p = rdma_resp + rpcrdma_fixed_maxsz + 1;
/* Skip past Write list */
while (*p++ != xdr_zero)
p += 1 + be32_to_cpup(p) * rpcrdma_segment_maxsz;
xdr_encode_write_chunk(p, rp_ch, consumed);
}
/* Parse the RPC Call's transport header.
*/
static void svc_rdma_get_write_arrays(__be32 *rdma_argp,
__be32 **write, __be32 **reply)
{
__be32 *p;
p = rdma_argp + rpcrdma_fixed_maxsz;
/* Read list */
while (*p++ != xdr_zero)
p += 5;
/* Write list */
if (*p != xdr_zero) {
*write = p;
while (*p++ != xdr_zero)
p += 1 + be32_to_cpu(*p) * 4;
} else {
*write = NULL;
p++;
}
/* Reply chunk */
if (*p != xdr_zero)
*reply = p;
else
*reply = NULL;
}
/* RPC-over-RDMA Version One private extension: Remote Invalidation.
* Responder's choice: requester signals it can handle Send With
* Invalidate, and responder chooses one rkey to invalidate.
*
* Find a candidate rkey to invalidate when sending a reply. Picks the
* first R_key it finds in the chunk lists.
*
* Returns zero if RPC's chunk lists are empty.
*/
static u32 svc_rdma_get_inv_rkey(__be32 *rdma_argp,
__be32 *wr_lst, __be32 *rp_ch)
{
__be32 *p;
p = rdma_argp + rpcrdma_fixed_maxsz;
if (*p != xdr_zero)
p += 2;
else if (wr_lst && be32_to_cpup(wr_lst + 1))
p = wr_lst + 2;
else if (rp_ch && be32_to_cpup(rp_ch + 1))
p = rp_ch + 2;
else
return 0;
return be32_to_cpup(p);
}
/* ib_dma_map_page() is used here because svc_rdma_dma_unmap()
* is used during completion to DMA-unmap this memory, and
* it uses ib_dma_unmap_page() exclusively.
*/
static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma,
struct svc_rdma_op_ctxt *ctxt,
unsigned int sge_no,
unsigned char *base,
unsigned int len)
{
unsigned long offset = (unsigned long)base & ~PAGE_MASK;
struct ib_device *dev = rdma->sc_cm_id->device;
dma_addr_t dma_addr;
dma_addr = ib_dma_map_page(dev, virt_to_page(base),
offset, len, DMA_TO_DEVICE);
if (ib_dma_mapping_error(dev, dma_addr))
goto out_maperr;
ctxt->sge[sge_no].addr = dma_addr;
ctxt->sge[sge_no].length = len;
ctxt->sge[sge_no].lkey = rdma->sc_pd->local_dma_lkey;
svc_rdma_count_mappings(rdma, ctxt);
return 0;
out_maperr:
pr_err("svcrdma: failed to map buffer\n");
return -EIO;
}
static int svc_rdma_dma_map_page(struct svcxprt_rdma *rdma,
struct svc_rdma_op_ctxt *ctxt,
unsigned int sge_no,
struct page *page,
unsigned int offset,
unsigned int len)
{
struct ib_device *dev = rdma->sc_cm_id->device;
dma_addr_t dma_addr;
dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE);
if (ib_dma_mapping_error(dev, dma_addr))
goto out_maperr;
ctxt->sge[sge_no].addr = dma_addr;
ctxt->sge[sge_no].length = len;
ctxt->sge[sge_no].lkey = rdma->sc_pd->local_dma_lkey;
svc_rdma_count_mappings(rdma, ctxt);
return 0;
out_maperr:
pr_err("svcrdma: failed to map page\n");
return -EIO;
}
/**
* svc_rdma_map_reply_hdr - DMA map the transport header buffer
* @rdma: controlling transport
* @ctxt: op_ctxt for the Send WR
* @rdma_resp: buffer containing transport header
* @len: length of transport header
*
* Returns:
* %0 if the header is DMA mapped,
* %-EIO if DMA mapping failed.
*/
int svc_rdma_map_reply_hdr(struct svcxprt_rdma *rdma,
struct svc_rdma_op_ctxt *ctxt,
__be32 *rdma_resp,
unsigned int len)
{
ctxt->direction = DMA_TO_DEVICE;
ctxt->pages[0] = virt_to_page(rdma_resp);
ctxt->count = 1;
return svc_rdma_dma_map_page(rdma, ctxt, 0, ctxt->pages[0], 0, len);
}
/* Load the xdr_buf into the ctxt's sge array, and DMA map each
* element as it is added.
*
* Returns the number of sge elements loaded on success, or
* a negative errno on failure.
*/
static int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma,
struct svc_rdma_op_ctxt *ctxt,
struct xdr_buf *xdr, __be32 *wr_lst)
{
unsigned int len, sge_no, remaining, page_off;
struct page **ppages;
unsigned char *base;
u32 xdr_pad;
int ret;
sge_no = 1;
ret = svc_rdma_dma_map_buf(rdma, ctxt, sge_no++,
xdr->head[0].iov_base,
xdr->head[0].iov_len);
if (ret < 0)
return ret;
/* If a Write chunk is present, the xdr_buf's page list
* is not included inline. However the Upper Layer may
* have added XDR padding in the tail buffer, and that
* should not be included inline.
*/
if (wr_lst) {
base = xdr->tail[0].iov_base;
len = xdr->tail[0].iov_len;
xdr_pad = xdr_padsize(xdr->page_len);
if (len && xdr_pad) {
base += xdr_pad;
len -= xdr_pad;
}
goto tail;
}
ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
page_off = xdr->page_base & ~PAGE_MASK;
remaining = xdr->page_len;
while (remaining) {
len = min_t(u32, PAGE_SIZE - page_off, remaining);
ret = svc_rdma_dma_map_page(rdma, ctxt, sge_no++,
*ppages++, page_off, len);
if (ret < 0)
return ret;
remaining -= len;
page_off = 0;
}
base = xdr->tail[0].iov_base;
len = xdr->tail[0].iov_len;
tail:
if (len) {
ret = svc_rdma_dma_map_buf(rdma, ctxt, sge_no++, base, len);
if (ret < 0)
return ret;
}
return sge_no - 1;
}
/* The svc_rqst and all resources it owns are released as soon as
* svc_rdma_sendto returns. Transfer pages under I/O to the ctxt
* so they are released by the Send completion handler.
*/
static void svc_rdma_save_io_pages(struct svc_rqst *rqstp,
struct svc_rdma_op_ctxt *ctxt)
{
int i, pages = rqstp->rq_next_page - rqstp->rq_respages;
ctxt->count += pages;
for (i = 0; i < pages; i++) {
ctxt->pages[i + 1] = rqstp->rq_respages[i];
rqstp->rq_respages[i] = NULL;
}
rqstp->rq_next_page = rqstp->rq_respages + 1;
}
/**
* svc_rdma_post_send_wr - Set up and post one Send Work Request
* @rdma: controlling transport
* @ctxt: op_ctxt for transmitting the Send WR
* @num_sge: number of SGEs to send
* @inv_rkey: R_key argument to Send With Invalidate, or zero
*
* Returns:
* %0 if the Send* was posted successfully,
* %-ENOTCONN if the connection was lost or dropped,
* %-EINVAL if there was a problem with the Send we built,
* %-ENOMEM if ib_post_send failed.
*/
int svc_rdma_post_send_wr(struct svcxprt_rdma *rdma,
struct svc_rdma_op_ctxt *ctxt, int num_sge,
u32 inv_rkey)
{
struct ib_send_wr *send_wr = &ctxt->send_wr;
dprintk("svcrdma: posting Send WR with %u sge(s)\n", num_sge);
send_wr->next = NULL;
ctxt->cqe.done = svc_rdma_wc_send;
send_wr->wr_cqe = &ctxt->cqe;
send_wr->sg_list = ctxt->sge;
send_wr->num_sge = num_sge;
send_wr->send_flags = IB_SEND_SIGNALED;
if (inv_rkey) {
send_wr->opcode = IB_WR_SEND_WITH_INV;
send_wr->ex.invalidate_rkey = inv_rkey;
} else {
send_wr->opcode = IB_WR_SEND;
}
return svc_rdma_send(rdma, send_wr);
}
/* Prepare the portion of the RPC Reply that will be transmitted
* via RDMA Send. The RPC-over-RDMA transport header is prepared
* in sge[0], and the RPC xdr_buf is prepared in following sges.
*
* Depending on whether a Write list or Reply chunk is present,
* the server may send all, a portion of, or none of the xdr_buf.
* In the latter case, only the transport header (sge[0]) is
* transmitted.
*
* RDMA Send is the last step of transmitting an RPC reply. Pages
* involved in the earlier RDMA Writes are here transferred out
* of the rqstp and into the ctxt's page array. These pages are
* DMA unmapped by each Write completion, but the subsequent Send
* completion finally releases these pages.
*
* Assumptions:
* - The Reply's transport header will never be larger than a page.
*/
static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma,
__be32 *rdma_argp, __be32 *rdma_resp,
struct svc_rqst *rqstp,
__be32 *wr_lst, __be32 *rp_ch)
{
struct svc_rdma_op_ctxt *ctxt;
u32 inv_rkey;
int ret;
dprintk("svcrdma: sending %s reply: head=%zu, pagelen=%u, tail=%zu\n",
(rp_ch ? "RDMA_NOMSG" : "RDMA_MSG"),
rqstp->rq_res.head[0].iov_len,
rqstp->rq_res.page_len,
rqstp->rq_res.tail[0].iov_len);
ctxt = svc_rdma_get_context(rdma);
ret = svc_rdma_map_reply_hdr(rdma, ctxt, rdma_resp,
svc_rdma_reply_hdr_len(rdma_resp));
if (ret < 0)
goto err;
if (!rp_ch) {
ret = svc_rdma_map_reply_msg(rdma, ctxt,
&rqstp->rq_res, wr_lst);
if (ret < 0)
goto err;
}
svc_rdma_save_io_pages(rqstp, ctxt);
inv_rkey = 0;
if (rdma->sc_snd_w_inv)
inv_rkey = svc_rdma_get_inv_rkey(rdma_argp, wr_lst, rp_ch);
ret = svc_rdma_post_send_wr(rdma, ctxt, 1 + ret, inv_rkey);
if (ret)
goto err;
return 0;
err:
svc_rdma_unmap_dma(ctxt);
svc_rdma_put_context(ctxt, 1);
return ret;
}
/* Given the client-provided Write and Reply chunks, the server was not
* able to form a complete reply. Return an RDMA_ERROR message so the
* client can retire this RPC transaction. As above, the Send completion
* routine releases payload pages that were part of a previous RDMA Write.
*
* Remote Invalidation is skipped for simplicity.
*/
static int svc_rdma_send_error_msg(struct svcxprt_rdma *rdma,
__be32 *rdma_resp, struct svc_rqst *rqstp)
{
struct svc_rdma_op_ctxt *ctxt;
__be32 *p;
int ret;
ctxt = svc_rdma_get_context(rdma);
/* Replace the original transport header with an
* RDMA_ERROR response. XID etc are preserved.
*/
p = rdma_resp + 3;
*p++ = rdma_error;
*p = err_chunk;
ret = svc_rdma_map_reply_hdr(rdma, ctxt, rdma_resp, 20);
if (ret < 0)
goto err;
svc_rdma_save_io_pages(rqstp, ctxt);
ret = svc_rdma_post_send_wr(rdma, ctxt, 1 + ret, 0);
if (ret)
goto err;
return 0;
err:
pr_err("svcrdma: failed to post Send WR (%d)\n", ret);
svc_rdma_unmap_dma(ctxt);
svc_rdma_put_context(ctxt, 1);
return ret;
}
void svc_rdma_prep_reply_hdr(struct svc_rqst *rqstp)
{
}
/**
* svc_rdma_sendto - Transmit an RPC reply
* @rqstp: processed RPC request, reply XDR already in ::rq_res
*
* Any resources still associated with @rqstp are released upon return.
* If no reply message was possible, the connection is closed.
*
* Returns:
* %0 if an RPC reply has been successfully posted,
* %-ENOMEM if a resource shortage occurred (connection is lost),
* %-ENOTCONN if posting failed (connection is lost).
*/
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);
__be32 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch;
struct xdr_buf *xdr = &rqstp->rq_res;
struct page *res_page;
int ret;
/* Find the call's chunk lists to decide how to send the reply.
* Receive places the Call's xprt header at the start of page 0.
*/
rdma_argp = page_address(rqstp->rq_pages[0]);
svc_rdma_get_write_arrays(rdma_argp, &wr_lst, &rp_ch);
dprintk("svcrdma: preparing response for XID 0x%08x\n",
be32_to_cpup(rdma_argp));
/* Create the RDMA response header. xprt->xpt_mutex,
* acquired in svc_send(), serializes RPC replies. The
* code path below that inserts the credit grant value
* into each transport header runs only inside this
* critical section.
*/
ret = -ENOMEM;
res_page = alloc_page(GFP_KERNEL);
if (!res_page)
goto err0;
rdma_resp = page_address(res_page);
p = rdma_resp;
*p++ = *rdma_argp;
*p++ = *(rdma_argp + 1);
*p++ = rdma->sc_fc_credits;
*p++ = rp_ch ? rdma_nomsg : rdma_msg;
/* Start with empty chunks */
*p++ = xdr_zero;
*p++ = xdr_zero;
*p = xdr_zero;
if (wr_lst) {
/* XXX: Presume the client sent only one Write chunk */
ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr);
if (ret < 0)
goto err2;
svc_rdma_xdr_encode_write_list(rdma_resp, wr_lst, ret);
}
if (rp_ch) {
ret = svc_rdma_send_reply_chunk(rdma, rp_ch, wr_lst, xdr);
if (ret < 0)
goto err2;
svc_rdma_xdr_encode_reply_chunk(rdma_resp, rp_ch, ret);
}
ret = svc_rdma_post_recv(rdma, GFP_KERNEL);
if (ret)
goto err1;
ret = svc_rdma_send_reply_msg(rdma, rdma_argp, rdma_resp, rqstp,
wr_lst, rp_ch);
if (ret < 0)
goto err0;
return 0;
err2:
if (ret != -E2BIG && ret != -EINVAL)
goto err1;
ret = svc_rdma_post_recv(rdma, GFP_KERNEL);
if (ret)
goto err1;
ret = svc_rdma_send_error_msg(rdma, rdma_resp, rqstp);
if (ret < 0)
goto err0;
return 0;
err1:
put_page(res_page);
err0:
pr_err("svcrdma: Could not send reply, err=%d. Closing transport.\n",
ret);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
return -ENOTCONN;
}
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