diff options
Diffstat (limited to 'net/sunrpc/xprtrdma/svc_rdma_sendto.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_sendto.c | 929 |
1 files changed, 929 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..4062cd624 --- /dev/null +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c @@ -0,0 +1,929 @@ +// 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/rpc_rdma.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 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; + + 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; + 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: + 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); + + 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; + + trace_svcrdma_wc_send(wc); + + atomic_inc(&rdma->sc_sq_avail); + wake_up(&rdma->sc_send_wait); + + ctxt = container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe); + 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); + if (wc->status != IB_WC_WR_FLUSH_ERR) + pr_err("svcrdma: Send: %s (%u/0x%x)\n", + ib_wc_status_msg(wc->status), + wc->status, wc->vendor_err); + } + + svc_xprt_put(&rdma->sc_xprt); +} + +/** + * svc_rdma_send - Post a single Send WR + * @rdma: transport on which to post the WR + * @wr: prepared Send WR 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 ib_send_wr *wr) +{ + int ret; + + might_sleep(); + + /* 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; + } + + svc_xprt_get(&rdma->sc_xprt); + trace_svcrdma_post_send(wr); + 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); + svc_xprt_put(&rdma->sc_xprt); + wake_up(&rdma->sc_send_wait); + return ret; +} + +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); +} + +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); + 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: + trace_svcrdma_dma_map_page(rdma, page); + 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_sync_reply_hdr - DMA sync the transport header buffer + * @rdma: controlling transport + * @ctxt: send_ctxt for the Send WR + * @len: length of transport header + * + */ +void svc_rdma_sync_reply_hdr(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *ctxt, + unsigned int len) +{ + ctxt->sc_sges[0].length = len; + ctxt->sc_send_wr.num_sge++; + ib_dma_sync_single_for_device(rdma->sc_pd->device, + ctxt->sc_sges[0].addr, len, + DMA_TO_DEVICE); +} + +/* If the xdr_buf has more elements than the device can + * transmit in a single RDMA Send, then the reply will + * have to be copied into a bounce buffer. + */ +static bool svc_rdma_pull_up_needed(struct svcxprt_rdma *rdma, + struct xdr_buf *xdr, + __be32 *wr_lst) +{ + int elements; + + /* xdr->head */ + elements = 1; + + /* xdr->pages */ + if (!wr_lst) { + 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; +} + +/* The device is not capable of sending the reply directly. + * Assemble the elements of @xdr into the transport header + * buffer. + */ +static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma, + struct svc_rdma_send_ctxt *ctxt, + struct xdr_buf *xdr, __be32 *wr_lst) +{ + unsigned char *dst, *tailbase; + unsigned int taillen; + + dst = ctxt->sc_xprt_buf; + dst += ctxt->sc_sges[0].length; + + 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 (wr_lst) { + u32 xdrpad; + + xdrpad = xdr_padsize(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); + + ctxt->sc_sges[0].length += xdr->len; + ib_dma_sync_single_for_device(rdma->sc_pd->device, + ctxt->sc_sges[0].addr, + ctxt->sc_sges[0].length, + DMA_TO_DEVICE); + + return 0; +} + +/* svc_rdma_map_reply_msg - Map the buffer holding RPC message + * @rdma: controlling transport + * @ctxt: send_ctxt for the Send WR + * @xdr: prepared xdr_buf containing RPC message + * @wr_lst: pointer to Call header's Write list, or NULL + * + * Load the xdr_buf into the ctxt's sge array, and DMA map each + * element as it is added. + * + * 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 *ctxt, + struct xdr_buf *xdr, __be32 *wr_lst) +{ + unsigned int len, remaining; + unsigned long page_off; + struct page **ppages; + unsigned char *base; + u32 xdr_pad; + int ret; + + if (svc_rdma_pull_up_needed(rdma, xdr, wr_lst)) + return svc_rdma_pull_up_reply_msg(rdma, ctxt, xdr, wr_lst); + + ++ctxt->sc_cur_sge_no; + ret = svc_rdma_dma_map_buf(rdma, ctxt, + 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); + + ++ctxt->sc_cur_sge_no; + ret = svc_rdma_dma_map_page(rdma, ctxt, *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) { + ++ctxt->sc_cur_sge_no; + ret = svc_rdma_dma_map_buf(rdma, ctxt, 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 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, + struct svc_rdma_send_ctxt *ctxt, + __be32 *rdma_argp, + struct svc_rqst *rqstp, + __be32 *wr_lst, __be32 *rp_ch) +{ + int ret; + + if (!rp_ch) { + ret = svc_rdma_map_reply_msg(rdma, ctxt, + &rqstp->rq_res, wr_lst); + if (ret < 0) + return ret; + } + + svc_rdma_save_io_pages(rqstp, ctxt); + + ctxt->sc_send_wr.opcode = IB_WR_SEND; + if (rdma->sc_snd_w_inv) { + ctxt->sc_send_wr.ex.invalidate_rkey = + svc_rdma_get_inv_rkey(rdma_argp, wr_lst, rp_ch); + if (ctxt->sc_send_wr.ex.invalidate_rkey) + ctxt->sc_send_wr.opcode = IB_WR_SEND_WITH_INV; + } + dprintk("svcrdma: posting Send WR with %u sge(s)\n", + ctxt->sc_send_wr.num_sge); + return svc_rdma_send(rdma, &ctxt->sc_send_wr); +} + +/* 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, + struct svc_rdma_send_ctxt *ctxt, + struct svc_rqst *rqstp) +{ + __be32 *p; + int ret; + + p = ctxt->sc_xprt_buf; + trace_svcrdma_err_chunk(*p); + p += 3; + *p++ = rdma_error; + *p = err_chunk; + svc_rdma_sync_reply_hdr(rdma, ctxt, RPCRDMA_HDRLEN_ERR); + + svc_rdma_save_io_pages(rqstp, ctxt); + + ctxt->sc_send_wr.opcode = IB_WR_SEND; + ret = svc_rdma_send(rdma, &ctxt->sc_send_wr); + if (ret) { + svc_rdma_send_ctxt_put(rdma, ctxt); + return ret; + } + + return 0; +} + +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); + struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; + __be32 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch; + struct xdr_buf *xdr = &rqstp->rq_res; + struct svc_rdma_send_ctxt *sctxt; + int ret; + + rdma_argp = rctxt->rc_recv_buf; + svc_rdma_get_write_arrays(rdma_argp, &wr_lst, &rp_ch); + + /* 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; + sctxt = svc_rdma_send_ctxt_get(rdma); + if (!sctxt) + goto err0; + rdma_resp = sctxt->sc_xprt_buf; + + 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); + } + + svc_rdma_sync_reply_hdr(rdma, sctxt, svc_rdma_reply_hdr_len(rdma_resp)); + ret = svc_rdma_send_reply_msg(rdma, sctxt, rdma_argp, rqstp, + wr_lst, rp_ch); + if (ret < 0) + goto err1; + return 0; + + err2: + if (ret != -E2BIG && ret != -EINVAL) + goto err1; + + ret = svc_rdma_send_error_msg(rdma, sctxt, rqstp); + if (ret < 0) + goto err1; + return 0; + + err1: + svc_rdma_send_ctxt_put(rdma, sctxt); + err0: + trace_svcrdma_send_failed(rqstp, ret); + set_bit(XPT_CLOSE, &xprt->xpt_flags); + return -ENOTCONN; +} |