diff options
Diffstat (limited to 'net/sunrpc/xprtrdma/svc_rdma_sendto.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_sendto.c | 1006 |
1 files changed, 1006 insertions, 0 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c new file mode 100644 index 000000000..c3d588b14 --- /dev/null +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c @@ -0,0 +1,1006 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause +/* + * Copyright (c) 2016-2018 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_send_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_send_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/spinlock.h> +#include <asm/unaligned.h> + +#include <rdma/ib_verbs.h> +#include <rdma/rdma_cm.h> + +#include <linux/sunrpc/debug.h> +#include <linux/sunrpc/svc_rdma.h> + +#include "xprt_rdma.h" +#include <trace/events/rpcrdma.h> + +#define RPCDBG_FACILITY RPCDBG_SVCXPRT + +static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc); + +static inline struct svc_rdma_send_ctxt * +svc_rdma_next_send_ctxt(struct list_head *list) +{ + return list_first_entry_or_null(list, struct svc_rdma_send_ctxt, + sc_list); +} + +static void svc_rdma_send_cid_init(struct svcxprt_rdma *rdma, + struct rpc_rdma_cid *cid) +{ + cid->ci_queue_id = rdma->sc_sq_cq->res.id; + cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids); +} + +static struct svc_rdma_send_ctxt * +svc_rdma_send_ctxt_alloc(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_send_ctxt *ctxt; + dma_addr_t addr; + void *buffer; + size_t size; + int i; + + size = sizeof(*ctxt); + size += rdma->sc_max_send_sges * sizeof(struct ib_sge); + ctxt = kmalloc(size, GFP_KERNEL); + if (!ctxt) + goto fail0; + buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL); + if (!buffer) + goto fail1; + addr = ib_dma_map_single(rdma->sc_pd->device, buffer, + rdma->sc_max_req_size, DMA_TO_DEVICE); + if (ib_dma_mapping_error(rdma->sc_pd->device, addr)) + goto fail2; + + svc_rdma_send_cid_init(rdma, &ctxt->sc_cid); + + ctxt->sc_send_wr.next = NULL; + ctxt->sc_send_wr.wr_cqe = &ctxt->sc_cqe; + ctxt->sc_send_wr.sg_list = ctxt->sc_sges; + ctxt->sc_send_wr.send_flags = IB_SEND_SIGNALED; + ctxt->sc_cqe.done = svc_rdma_wc_send; + ctxt->sc_xprt_buf = buffer; + xdr_buf_init(&ctxt->sc_hdrbuf, ctxt->sc_xprt_buf, + rdma->sc_max_req_size); + ctxt->sc_sges[0].addr = addr; + + for (i = 0; i < rdma->sc_max_send_sges; i++) + ctxt->sc_sges[i].lkey = rdma->sc_pd->local_dma_lkey; + return ctxt; + +fail2: + kfree(buffer); +fail1: + kfree(ctxt); +fail0: + return NULL; +} + +/** + * svc_rdma_send_ctxts_destroy - Release all send_ctxt's for an xprt + * @rdma: svcxprt_rdma being torn down + * + */ +void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_send_ctxt *ctxt; + + while ((ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts))) { + list_del(&ctxt->sc_list); + ib_dma_unmap_single(rdma->sc_pd->device, + ctxt->sc_sges[0].addr, + rdma->sc_max_req_size, + DMA_TO_DEVICE); + kfree(ctxt->sc_xprt_buf); + kfree(ctxt); + } +} + +/** + * svc_rdma_send_ctxt_get - Get a free send_ctxt + * @rdma: controlling svcxprt_rdma + * + * Returns a ready-to-use send_ctxt, or NULL if none are + * available and a fresh one cannot be allocated. + */ +struct svc_rdma_send_ctxt *svc_rdma_send_ctxt_get(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_send_ctxt *ctxt; + + spin_lock(&rdma->sc_send_lock); + ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts); + if (!ctxt) + goto out_empty; + list_del(&ctxt->sc_list); + spin_unlock(&rdma->sc_send_lock); + +out: + rpcrdma_set_xdrlen(&ctxt->sc_hdrbuf, 0); + xdr_init_encode(&ctxt->sc_stream, &ctxt->sc_hdrbuf, + ctxt->sc_xprt_buf, NULL); + + ctxt->sc_send_wr.num_sge = 0; + ctxt->sc_cur_sge_no = 0; + ctxt->sc_page_count = 0; + return ctxt; + +out_empty: + spin_unlock(&rdma->sc_send_lock); + ctxt = svc_rdma_send_ctxt_alloc(rdma); + if (!ctxt) + return NULL; + goto out; +} + +/** + * svc_rdma_send_ctxt_put - Return send_ctxt to free list + * @rdma: controlling svcxprt_rdma + * @ctxt: object to return to the free list + * + * Pages left in sc_pages are DMA unmapped and released. + */ +void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *ctxt) +{ + struct ib_device *device = rdma->sc_cm_id->device; + unsigned int i; + + /* The first SGE contains the transport header, which + * remains mapped until @ctxt is destroyed. + */ + for (i = 1; i < ctxt->sc_send_wr.num_sge; i++) { + ib_dma_unmap_page(device, + ctxt->sc_sges[i].addr, + ctxt->sc_sges[i].length, + DMA_TO_DEVICE); + trace_svcrdma_dma_unmap_page(rdma, + ctxt->sc_sges[i].addr, + ctxt->sc_sges[i].length); + } + + for (i = 0; i < ctxt->sc_page_count; ++i) + put_page(ctxt->sc_pages[i]); + + spin_lock(&rdma->sc_send_lock); + list_add(&ctxt->sc_list, &rdma->sc_send_ctxts); + spin_unlock(&rdma->sc_send_lock); +} + +/** + * svc_rdma_wc_send - Invoked by RDMA provider for each polled Send WC + * @cq: Completion Queue context + * @wc: Work Completion object + * + * NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that + * the Send completion handler could be running. + */ +static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc) +{ + struct svcxprt_rdma *rdma = cq->cq_context; + struct ib_cqe *cqe = wc->wr_cqe; + struct svc_rdma_send_ctxt *ctxt = + container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe); + + trace_svcrdma_wc_send(wc, &ctxt->sc_cid); + + atomic_inc(&rdma->sc_sq_avail); + wake_up(&rdma->sc_send_wait); + + svc_rdma_send_ctxt_put(rdma, ctxt); + + if (unlikely(wc->status != IB_WC_SUCCESS)) { + set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); + svc_xprt_enqueue(&rdma->sc_xprt); + } +} + +/** + * svc_rdma_send - Post a single Send WR + * @rdma: transport on which to post the WR + * @ctxt: send ctxt with a Send WR ready to post + * + * Returns zero the Send WR was posted successfully. Otherwise, a + * negative errno is returned. + */ +int svc_rdma_send(struct svcxprt_rdma *rdma, struct svc_rdma_send_ctxt *ctxt) +{ + struct ib_send_wr *wr = &ctxt->sc_send_wr; + int ret; + + might_sleep(); + + /* Sync the transport header buffer */ + ib_dma_sync_single_for_device(rdma->sc_pd->device, + wr->sg_list[0].addr, + wr->sg_list[0].length, + DMA_TO_DEVICE); + + /* If the SQ is full, wait until an SQ entry is available */ + while (1) { + if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) { + atomic_inc(&rdma_stat_sq_starve); + trace_svcrdma_sq_full(rdma); + atomic_inc(&rdma->sc_sq_avail); + wait_event(rdma->sc_send_wait, + atomic_read(&rdma->sc_sq_avail) > 1); + if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) + return -ENOTCONN; + trace_svcrdma_sq_retry(rdma); + continue; + } + + trace_svcrdma_post_send(ctxt); + ret = ib_post_send(rdma->sc_qp, wr, NULL); + if (ret) + break; + return 0; + } + + trace_svcrdma_sq_post_err(rdma, ret); + set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); + wake_up(&rdma->sc_send_wait); + return ret; +} + +/** + * svc_rdma_encode_read_list - Encode RPC Reply's Read chunk list + * @sctxt: Send context for the RPC Reply + * + * Return values: + * On success, returns length in bytes of the Reply XDR buffer + * that was consumed by the Reply Read list + * %-EMSGSIZE on XDR buffer overflow + */ +static ssize_t svc_rdma_encode_read_list(struct svc_rdma_send_ctxt *sctxt) +{ + /* RPC-over-RDMA version 1 replies never have a Read list. */ + return xdr_stream_encode_item_absent(&sctxt->sc_stream); +} + +/** + * svc_rdma_encode_write_segment - Encode one Write segment + * @src: matching Write chunk in the RPC Call header + * @sctxt: Send context for the RPC Reply + * @remaining: remaining bytes of the payload left in the Write chunk + * + * Return values: + * On success, returns length in bytes of the Reply XDR buffer + * that was consumed by the Write segment + * %-EMSGSIZE on XDR buffer overflow + */ +static ssize_t svc_rdma_encode_write_segment(__be32 *src, + struct svc_rdma_send_ctxt *sctxt, + unsigned int *remaining) +{ + __be32 *p; + const size_t len = rpcrdma_segment_maxsz * sizeof(*p); + u32 handle, length; + u64 offset; + + p = xdr_reserve_space(&sctxt->sc_stream, len); + if (!p) + return -EMSGSIZE; + + xdr_decode_rdma_segment(src, &handle, &length, &offset); + + if (*remaining < length) { + /* segment only partly filled */ + length = *remaining; + *remaining = 0; + } else { + /* entire segment was consumed */ + *remaining -= length; + } + xdr_encode_rdma_segment(p, handle, length, offset); + + trace_svcrdma_encode_wseg(handle, length, offset); + return len; +} + +/** + * svc_rdma_encode_write_chunk - Encode one Write chunk + * @src: matching Write chunk in the RPC Call header + * @sctxt: Send context for the RPC Reply + * @remaining: size in bytes of the payload in the Write chunk + * + * Copy a Write chunk from the Call transport header to the + * Reply transport header. Update each segment's length field + * to reflect the number of bytes written in that segment. + * + * Return values: + * On success, returns length in bytes of the Reply XDR buffer + * that was consumed by the Write chunk + * %-EMSGSIZE on XDR buffer overflow + */ +static ssize_t svc_rdma_encode_write_chunk(__be32 *src, + struct svc_rdma_send_ctxt *sctxt, + unsigned int remaining) +{ + unsigned int i, nsegs; + ssize_t len, ret; + + len = 0; + trace_svcrdma_encode_write_chunk(remaining); + + src++; + ret = xdr_stream_encode_item_present(&sctxt->sc_stream); + if (ret < 0) + return -EMSGSIZE; + len += ret; + + nsegs = be32_to_cpup(src++); + ret = xdr_stream_encode_u32(&sctxt->sc_stream, nsegs); + if (ret < 0) + return -EMSGSIZE; + len += ret; + + for (i = nsegs; i; i--) { + ret = svc_rdma_encode_write_segment(src, sctxt, &remaining); + if (ret < 0) + return -EMSGSIZE; + src += rpcrdma_segment_maxsz; + len += ret; + } + + return len; +} + +/** + * svc_rdma_encode_write_list - Encode RPC Reply's Write chunk list + * @rctxt: Reply context with information about the RPC Call + * @sctxt: Send context for the RPC Reply + * @length: size in bytes of the payload in the first Write chunk + * + * The client provides a Write chunk 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 + * + * Return values: + * On success, returns length in bytes of the Reply XDR buffer + * that was consumed by the Reply's Write list + * %-EMSGSIZE on XDR buffer overflow + */ +static ssize_t +svc_rdma_encode_write_list(const struct svc_rdma_recv_ctxt *rctxt, + struct svc_rdma_send_ctxt *sctxt, + unsigned int length) +{ + ssize_t len, ret; + + ret = svc_rdma_encode_write_chunk(rctxt->rc_write_list, sctxt, length); + if (ret < 0) + return ret; + len = ret; + + /* Terminate the Write list */ + ret = xdr_stream_encode_item_absent(&sctxt->sc_stream); + if (ret < 0) + return ret; + + return len + ret; +} + +/** + * svc_rdma_encode_reply_chunk - Encode RPC Reply's Reply chunk + * @rctxt: Reply context with information about the RPC Call + * @sctxt: Send context for the RPC Reply + * @length: size in bytes of the payload in the Reply chunk + * + * Assumptions: + * - Reply can always fit in the client-provided Reply chunk + * + * Return values: + * On success, returns length in bytes of the Reply XDR buffer + * that was consumed by the Reply's Reply chunk + * %-EMSGSIZE on XDR buffer overflow + */ +static ssize_t +svc_rdma_encode_reply_chunk(const struct svc_rdma_recv_ctxt *rctxt, + struct svc_rdma_send_ctxt *sctxt, + unsigned int length) +{ + return svc_rdma_encode_write_chunk(rctxt->rc_reply_chunk, sctxt, + length); +} + +static int svc_rdma_dma_map_page(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *ctxt, + struct page *page, + unsigned long 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); + trace_svcrdma_dma_map_page(rdma, dma_addr, len); + if (ib_dma_mapping_error(dev, dma_addr)) + goto out_maperr; + + ctxt->sc_sges[ctxt->sc_cur_sge_no].addr = dma_addr; + ctxt->sc_sges[ctxt->sc_cur_sge_no].length = len; + ctxt->sc_send_wr.num_sge++; + return 0; + +out_maperr: + return -EIO; +} + +/* ib_dma_map_page() is used here because svc_rdma_dma_unmap() + * handles DMA-unmap and it uses ib_dma_unmap_page() exclusively. + */ +static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *ctxt, + unsigned char *base, + unsigned int len) +{ + return svc_rdma_dma_map_page(rdma, ctxt, virt_to_page(base), + offset_in_page(base), len); +} + +/** + * svc_rdma_pull_up_needed - Determine whether to use pull-up + * @rdma: controlling transport + * @sctxt: send_ctxt for the Send WR + * @rctxt: Write and Reply chunks provided by client + * @xdr: xdr_buf containing RPC message to transmit + * + * Returns: + * %true if pull-up must be used + * %false otherwise + */ +static bool svc_rdma_pull_up_needed(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *sctxt, + const struct svc_rdma_recv_ctxt *rctxt, + struct xdr_buf *xdr) +{ + int elements; + + /* For small messages, copying bytes is cheaper than DMA mapping. + */ + if (sctxt->sc_hdrbuf.len + xdr->len < RPCRDMA_PULLUP_THRESH) + return true; + + /* Check whether the xdr_buf has more elements than can + * fit in a single RDMA Send. + */ + /* xdr->head */ + elements = 1; + + /* xdr->pages */ + if (!rctxt || !rctxt->rc_write_list) { + unsigned int remaining; + unsigned long pageoff; + + pageoff = xdr->page_base & ~PAGE_MASK; + remaining = xdr->page_len; + while (remaining) { + ++elements; + remaining -= min_t(u32, PAGE_SIZE - pageoff, + remaining); + pageoff = 0; + } + } + + /* xdr->tail */ + if (xdr->tail[0].iov_len) + ++elements; + + /* assume 1 SGE is needed for the transport header */ + return elements >= rdma->sc_max_send_sges; +} + +/** + * svc_rdma_pull_up_reply_msg - Copy Reply into a single buffer + * @rdma: controlling transport + * @sctxt: send_ctxt for the Send WR; xprt hdr is already prepared + * @rctxt: Write and Reply chunks provided by client + * @xdr: prepared xdr_buf containing RPC message + * + * The device is not capable of sending the reply directly. + * Assemble the elements of @xdr into the transport header buffer. + * + * Returns zero on success, or a negative errno on failure. + */ +static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *sctxt, + const struct svc_rdma_recv_ctxt *rctxt, + const struct xdr_buf *xdr) +{ + unsigned char *dst, *tailbase; + unsigned int taillen; + + dst = sctxt->sc_xprt_buf + sctxt->sc_hdrbuf.len; + memcpy(dst, xdr->head[0].iov_base, xdr->head[0].iov_len); + dst += xdr->head[0].iov_len; + + tailbase = xdr->tail[0].iov_base; + taillen = xdr->tail[0].iov_len; + if (rctxt && rctxt->rc_write_list) { + u32 xdrpad; + + xdrpad = xdr_pad_size(xdr->page_len); + if (taillen && xdrpad) { + tailbase += xdrpad; + taillen -= xdrpad; + } + } else { + unsigned int len, remaining; + unsigned long pageoff; + struct page **ppages; + + ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); + pageoff = xdr->page_base & ~PAGE_MASK; + remaining = xdr->page_len; + while (remaining) { + len = min_t(u32, PAGE_SIZE - pageoff, remaining); + + memcpy(dst, page_address(*ppages) + pageoff, len); + remaining -= len; + dst += len; + pageoff = 0; + ppages++; + } + } + + if (taillen) + memcpy(dst, tailbase, taillen); + + sctxt->sc_sges[0].length += xdr->len; + trace_svcrdma_send_pullup(sctxt->sc_sges[0].length); + return 0; +} + +/* svc_rdma_map_reply_msg - DMA map the buffer holding RPC message + * @rdma: controlling transport + * @sctxt: send_ctxt for the Send WR + * @rctxt: Write and Reply chunks provided by client + * @xdr: prepared xdr_buf containing RPC message + * + * Load the xdr_buf into the ctxt's sge array, and DMA map each + * element as it is added. The Send WR's num_sge field is set. + * + * Returns zero on success, or a negative errno on failure. + */ +int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *sctxt, + const struct svc_rdma_recv_ctxt *rctxt, + struct xdr_buf *xdr) +{ + unsigned int len, remaining; + unsigned long page_off; + struct page **ppages; + unsigned char *base; + u32 xdr_pad; + int ret; + + /* Set up the (persistently-mapped) transport header SGE. */ + sctxt->sc_send_wr.num_sge = 1; + sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len; + + /* If there is a Reply chunk, nothing follows the transport + * header, and we're done here. + */ + if (rctxt && rctxt->rc_reply_chunk) + return 0; + + /* For pull-up, svc_rdma_send() will sync the transport header. + * No additional DMA mapping is necessary. + */ + if (svc_rdma_pull_up_needed(rdma, sctxt, rctxt, xdr)) + return svc_rdma_pull_up_reply_msg(rdma, sctxt, rctxt, xdr); + + ++sctxt->sc_cur_sge_no; + ret = svc_rdma_dma_map_buf(rdma, sctxt, + 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 (rctxt && rctxt->rc_write_list) { + base = xdr->tail[0].iov_base; + len = xdr->tail[0].iov_len; + xdr_pad = xdr_pad_size(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); + + ++sctxt->sc_cur_sge_no; + ret = svc_rdma_dma_map_page(rdma, sctxt, *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) { + ++sctxt->sc_cur_sge_no; + ret = svc_rdma_dma_map_buf(rdma, sctxt, base, len); + if (ret < 0) + return ret; + } + + return 0; +} + +/* 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_send_ctxt *ctxt) +{ + int i, pages = rqstp->rq_next_page - rqstp->rq_respages; + + ctxt->sc_page_count += pages; + for (i = 0; i < pages; i++) { + ctxt->sc_pages[i] = rqstp->rq_respages[i]; + rqstp->rq_respages[i] = NULL; + } + + /* Prevent svc_xprt_release from releasing pages in rq_pages */ + rqstp->rq_next_page = rqstp->rq_respages; +} + +/* Prepare the portion of the RPC Reply that will be transmitted + * via RDMA Send. The RPC-over-RDMA transport header is prepared + * in sc_sges[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 (sc_sges[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 sctxt'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, + struct svc_rdma_send_ctxt *sctxt, + const struct svc_rdma_recv_ctxt *rctxt, + struct svc_rqst *rqstp) +{ + int ret; + + ret = svc_rdma_map_reply_msg(rdma, sctxt, rctxt, &rqstp->rq_res); + if (ret < 0) + return ret; + + svc_rdma_save_io_pages(rqstp, sctxt); + + if (rctxt->rc_inv_rkey) { + sctxt->sc_send_wr.opcode = IB_WR_SEND_WITH_INV; + sctxt->sc_send_wr.ex.invalidate_rkey = rctxt->rc_inv_rkey; + } else { + sctxt->sc_send_wr.opcode = IB_WR_SEND; + } + return svc_rdma_send(rdma, sctxt); +} + +/** + * svc_rdma_send_error_msg - Send an RPC/RDMA v1 error response + * @rdma: controlling transport context + * @sctxt: Send context for the response + * @rctxt: Receive context for incoming bad message + * @status: negative errno indicating error that occurred + * + * Given the client-provided Read, Write, and Reply chunks, the + * server was not able to parse the Call or form a complete Reply. + * Return an RDMA_ERROR message so the client can retire the RPC + * transaction. + * + * The caller does not have to release @sctxt. It is released by + * Send completion, or by this function on error. + */ +void svc_rdma_send_error_msg(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *sctxt, + struct svc_rdma_recv_ctxt *rctxt, + int status) +{ + __be32 *rdma_argp = rctxt->rc_recv_buf; + __be32 *p; + + rpcrdma_set_xdrlen(&sctxt->sc_hdrbuf, 0); + xdr_init_encode(&sctxt->sc_stream, &sctxt->sc_hdrbuf, + sctxt->sc_xprt_buf, NULL); + + p = xdr_reserve_space(&sctxt->sc_stream, + rpcrdma_fixed_maxsz * sizeof(*p)); + if (!p) + goto put_ctxt; + + *p++ = *rdma_argp; + *p++ = *(rdma_argp + 1); + *p++ = rdma->sc_fc_credits; + *p = rdma_error; + + switch (status) { + case -EPROTONOSUPPORT: + p = xdr_reserve_space(&sctxt->sc_stream, 3 * sizeof(*p)); + if (!p) + goto put_ctxt; + + *p++ = err_vers; + *p++ = rpcrdma_version; + *p = rpcrdma_version; + trace_svcrdma_err_vers(*rdma_argp); + break; + default: + p = xdr_reserve_space(&sctxt->sc_stream, sizeof(*p)); + if (!p) + goto put_ctxt; + + *p = err_chunk; + trace_svcrdma_err_chunk(*rdma_argp); + } + + /* Remote Invalidation is skipped for simplicity. */ + sctxt->sc_send_wr.num_sge = 1; + sctxt->sc_send_wr.opcode = IB_WR_SEND; + sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len; + if (svc_rdma_send(rdma, sctxt)) + goto put_ctxt; + return; + +put_ctxt: + svc_rdma_send_ctxt_put(rdma, sctxt); +} + +/** + * 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); + struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; + __be32 *rdma_argp = rctxt->rc_recv_buf; + __be32 *wr_lst = rctxt->rc_write_list; + __be32 *rp_ch = rctxt->rc_reply_chunk; + struct xdr_buf *xdr = &rqstp->rq_res; + struct svc_rdma_send_ctxt *sctxt; + __be32 *p; + int ret; + + ret = -ENOTCONN; + if (svc_xprt_is_dead(xprt)) + goto err0; + + ret = -ENOMEM; + sctxt = svc_rdma_send_ctxt_get(rdma); + if (!sctxt) + goto err0; + + p = xdr_reserve_space(&sctxt->sc_stream, + rpcrdma_fixed_maxsz * sizeof(*p)); + if (!p) + goto err0; + *p++ = *rdma_argp; + *p++ = *(rdma_argp + 1); + *p++ = rdma->sc_fc_credits; + *p = rp_ch ? rdma_nomsg : rdma_msg; + + if (svc_rdma_encode_read_list(sctxt) < 0) + goto err0; + if (wr_lst) { + /* XXX: Presume the client sent only one Write chunk */ + unsigned long offset; + unsigned int length; + + if (rctxt->rc_read_payload_length) { + offset = rctxt->rc_read_payload_offset; + length = rctxt->rc_read_payload_length; + } else { + offset = xdr->head[0].iov_len; + length = xdr->page_len; + } + ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr, offset, + length); + if (ret < 0) + goto err2; + if (svc_rdma_encode_write_list(rctxt, sctxt, length) < 0) + goto err0; + } else { + if (xdr_stream_encode_item_absent(&sctxt->sc_stream) < 0) + goto err0; + } + if (rp_ch) { + ret = svc_rdma_send_reply_chunk(rdma, rctxt, &rqstp->rq_res); + if (ret < 0) + goto err2; + if (svc_rdma_encode_reply_chunk(rctxt, sctxt, ret) < 0) + goto err0; + } else { + if (xdr_stream_encode_item_absent(&sctxt->sc_stream) < 0) + goto err0; + } + + ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp); + if (ret < 0) + goto err1; + return 0; + + err2: + if (ret != -E2BIG && ret != -EINVAL) + goto err1; + + /* Send completion releases payload pages that were part + * of previously posted RDMA Writes. + */ + svc_rdma_save_io_pages(rqstp, sctxt); + svc_rdma_send_error_msg(rdma, sctxt, rctxt, ret); + return 0; + + err1: + svc_rdma_send_ctxt_put(rdma, sctxt); + err0: + trace_svcrdma_send_err(rqstp, ret); + set_bit(XPT_CLOSE, &xprt->xpt_flags); + return -ENOTCONN; +} + +/** + * svc_rdma_read_payload - special processing for a READ payload + * @rqstp: svc_rqst to operate on + * @offset: payload's byte offset in @xdr + * @length: size of payload, in bytes + * + * Returns zero on success. + * + * For the moment, just record the xdr_buf location of the READ + * payload. svc_rdma_sendto will use that location later when + * we actually send the payload. + */ +int svc_rdma_read_payload(struct svc_rqst *rqstp, unsigned int offset, + unsigned int length) +{ + struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; + + /* XXX: Just one READ payload slot for now, since our + * transport implementation currently supports only one + * Write chunk. + */ + rctxt->rc_read_payload_offset = offset; + rctxt->rc_read_payload_length = length; + + return 0; +} |