// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2016-2018 Oracle. All rights reserved. * * Use the core R/W API to move RPC-over-RDMA Read and Write chunks. */ #include #include #include #include #include "xprt_rdma.h" #include #define RPCDBG_FACILITY RPCDBG_SVCXPRT static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc); static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc); /* Each R/W context contains state for one chain of RDMA Read or * Write Work Requests. * * Each WR chain handles a single contiguous server-side buffer, * because scatterlist entries after the first have to start on * page alignment. xdr_buf iovecs cannot guarantee alignment. * * Each WR chain handles only one R_key. Each RPC-over-RDMA segment * from a client may contain a unique R_key, so each WR chain moves * up to one segment at a time. * * The scatterlist makes this data structure over 4KB in size. To * make it less likely to fail, and to handle the allocation for * smaller I/O requests without disabling bottom-halves, these * contexts are created on demand, but cached and reused until the * controlling svcxprt_rdma is destroyed. */ struct svc_rdma_rw_ctxt { struct list_head rw_list; struct rdma_rw_ctx rw_ctx; int rw_nents; struct sg_table rw_sg_table; struct scatterlist rw_first_sgl[0]; }; static inline struct svc_rdma_rw_ctxt * svc_rdma_next_ctxt(struct list_head *list) { return list_first_entry_or_null(list, struct svc_rdma_rw_ctxt, rw_list); } static struct svc_rdma_rw_ctxt * svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges) { struct svc_rdma_rw_ctxt *ctxt; spin_lock(&rdma->sc_rw_ctxt_lock); ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts); if (ctxt) { list_del(&ctxt->rw_list); spin_unlock(&rdma->sc_rw_ctxt_lock); } else { spin_unlock(&rdma->sc_rw_ctxt_lock); ctxt = kmalloc(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE), GFP_KERNEL); if (!ctxt) goto out; INIT_LIST_HEAD(&ctxt->rw_list); } ctxt->rw_sg_table.sgl = ctxt->rw_first_sgl; if (sg_alloc_table_chained(&ctxt->rw_sg_table, sges, ctxt->rw_sg_table.sgl, SG_CHUNK_SIZE)) { kfree(ctxt); ctxt = NULL; } out: return ctxt; } static void svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma, struct svc_rdma_rw_ctxt *ctxt) { sg_free_table_chained(&ctxt->rw_sg_table, SG_CHUNK_SIZE); spin_lock(&rdma->sc_rw_ctxt_lock); list_add(&ctxt->rw_list, &rdma->sc_rw_ctxts); spin_unlock(&rdma->sc_rw_ctxt_lock); } /** * svc_rdma_destroy_rw_ctxts - Free accumulated R/W contexts * @rdma: transport about to be destroyed * */ void svc_rdma_destroy_rw_ctxts(struct svcxprt_rdma *rdma) { struct svc_rdma_rw_ctxt *ctxt; while ((ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts)) != NULL) { list_del(&ctxt->rw_list); kfree(ctxt); } } /* A chunk context tracks all I/O for moving one Read or Write * chunk. This is a a set of rdma_rw's that handle data movement * for all segments of one chunk. * * These are small, acquired with a single allocator call, and * no more than one is needed per chunk. They are allocated on * demand, and not cached. */ struct svc_rdma_chunk_ctxt { struct ib_cqe cc_cqe; struct svcxprt_rdma *cc_rdma; struct list_head cc_rwctxts; int cc_sqecount; }; static void svc_rdma_cc_init(struct svcxprt_rdma *rdma, struct svc_rdma_chunk_ctxt *cc) { cc->cc_rdma = rdma; svc_xprt_get(&rdma->sc_xprt); INIT_LIST_HEAD(&cc->cc_rwctxts); cc->cc_sqecount = 0; } static void svc_rdma_cc_release(struct svc_rdma_chunk_ctxt *cc, enum dma_data_direction dir) { struct svcxprt_rdma *rdma = cc->cc_rdma; struct svc_rdma_rw_ctxt *ctxt; while ((ctxt = svc_rdma_next_ctxt(&cc->cc_rwctxts)) != NULL) { list_del(&ctxt->rw_list); rdma_rw_ctx_destroy(&ctxt->rw_ctx, rdma->sc_qp, rdma->sc_port_num, ctxt->rw_sg_table.sgl, ctxt->rw_nents, dir); svc_rdma_put_rw_ctxt(rdma, ctxt); } svc_xprt_put(&rdma->sc_xprt); } /* State for sending a Write or Reply chunk. * - Tracks progress of writing one chunk over all its segments * - Stores arguments for the SGL constructor functions */ struct svc_rdma_write_info { /* write state of this chunk */ unsigned int wi_seg_off; unsigned int wi_seg_no; unsigned int wi_nsegs; __be32 *wi_segs; /* SGL constructor arguments */ struct xdr_buf *wi_xdr; unsigned char *wi_base; unsigned int wi_next_off; struct svc_rdma_chunk_ctxt wi_cc; }; static struct svc_rdma_write_info * svc_rdma_write_info_alloc(struct svcxprt_rdma *rdma, __be32 *chunk) { struct svc_rdma_write_info *info; info = kmalloc(sizeof(*info), GFP_KERNEL); if (!info) return info; info->wi_seg_off = 0; info->wi_seg_no = 0; info->wi_nsegs = be32_to_cpup(++chunk); info->wi_segs = ++chunk; svc_rdma_cc_init(rdma, &info->wi_cc); info->wi_cc.cc_cqe.done = svc_rdma_write_done; return info; } static void svc_rdma_write_info_free(struct svc_rdma_write_info *info) { svc_rdma_cc_release(&info->wi_cc, DMA_TO_DEVICE); kfree(info); } /** * svc_rdma_write_done - Write chunk completion * @cq: controlling Completion Queue * @wc: Work Completion * * Pages under I/O are freed by a subsequent Send completion. */ static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc) { struct ib_cqe *cqe = wc->wr_cqe; struct svc_rdma_chunk_ctxt *cc = container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe); struct svcxprt_rdma *rdma = cc->cc_rdma; struct svc_rdma_write_info *info = container_of(cc, struct svc_rdma_write_info, wi_cc); trace_svcrdma_wc_write(wc); atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail); wake_up(&rdma->sc_send_wait); if (unlikely(wc->status != IB_WC_SUCCESS)) set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); svc_rdma_write_info_free(info); } /* State for pulling a Read chunk. */ struct svc_rdma_read_info { struct svc_rdma_recv_ctxt *ri_readctxt; unsigned int ri_position; unsigned int ri_pageno; unsigned int ri_pageoff; unsigned int ri_chunklen; struct svc_rdma_chunk_ctxt ri_cc; }; static struct svc_rdma_read_info * svc_rdma_read_info_alloc(struct svcxprt_rdma *rdma) { struct svc_rdma_read_info *info; info = kmalloc(sizeof(*info), GFP_KERNEL); if (!info) return info; svc_rdma_cc_init(rdma, &info->ri_cc); info->ri_cc.cc_cqe.done = svc_rdma_wc_read_done; return info; } static void svc_rdma_read_info_free(struct svc_rdma_read_info *info) { svc_rdma_cc_release(&info->ri_cc, DMA_FROM_DEVICE); kfree(info); } /** * svc_rdma_wc_read_done - Handle completion of an RDMA Read ctx * @cq: controlling Completion Queue * @wc: Work Completion * */ static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc) { struct ib_cqe *cqe = wc->wr_cqe; struct svc_rdma_chunk_ctxt *cc = container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe); struct svcxprt_rdma *rdma = cc->cc_rdma; struct svc_rdma_read_info *info = container_of(cc, struct svc_rdma_read_info, ri_cc); trace_svcrdma_wc_read(wc); atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail); wake_up(&rdma->sc_send_wait); if (unlikely(wc->status != IB_WC_SUCCESS)) { set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); svc_rdma_recv_ctxt_put(rdma, info->ri_readctxt); } else { spin_lock(&rdma->sc_rq_dto_lock); list_add_tail(&info->ri_readctxt->rc_list, &rdma->sc_read_complete_q); /* Note the unlock pairs with the smp_rmb in svc_xprt_ready: */ set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags); spin_unlock(&rdma->sc_rq_dto_lock); svc_xprt_enqueue(&rdma->sc_xprt); } svc_rdma_read_info_free(info); } /* This function sleeps when the transport's Send Queue is congested. * * Assumptions: * - If ib_post_send() succeeds, only one completion is expected, * even if one or more WRs are flushed. This is true when posting * an rdma_rw_ctx or when posting a single signaled WR. */ static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc) { struct svcxprt_rdma *rdma = cc->cc_rdma; struct svc_xprt *xprt = &rdma->sc_xprt; struct ib_send_wr *first_wr; const struct ib_send_wr *bad_wr; struct list_head *tmp; struct ib_cqe *cqe; int ret; if (cc->cc_sqecount > rdma->sc_sq_depth) return -EINVAL; first_wr = NULL; cqe = &cc->cc_cqe; list_for_each(tmp, &cc->cc_rwctxts) { struct svc_rdma_rw_ctxt *ctxt; ctxt = list_entry(tmp, struct svc_rdma_rw_ctxt, rw_list); first_wr = rdma_rw_ctx_wrs(&ctxt->rw_ctx, rdma->sc_qp, rdma->sc_port_num, cqe, first_wr); cqe = NULL; } do { if (atomic_sub_return(cc->cc_sqecount, &rdma->sc_sq_avail) > 0) { ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr); trace_svcrdma_post_rw(&cc->cc_cqe, cc->cc_sqecount, ret); if (ret) break; return 0; } trace_svcrdma_sq_full(rdma); atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail); wait_event(rdma->sc_send_wait, atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount); trace_svcrdma_sq_retry(rdma); } while (1); set_bit(XPT_CLOSE, &xprt->xpt_flags); /* If even one was posted, there will be a completion. */ if (bad_wr != first_wr) return 0; atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail); wake_up(&rdma->sc_send_wait); return -ENOTCONN; } /* Build and DMA-map an SGL that covers one kvec in an xdr_buf */ static void svc_rdma_vec_to_sg(struct svc_rdma_write_info *info, unsigned int len, struct svc_rdma_rw_ctxt *ctxt) { struct scatterlist *sg = ctxt->rw_sg_table.sgl; sg_set_buf(&sg[0], info->wi_base, len); info->wi_base += len; ctxt->rw_nents = 1; } /* Build and DMA-map an SGL that covers part of an xdr_buf's pagelist. */ static void svc_rdma_pagelist_to_sg(struct svc_rdma_write_info *info, unsigned int remaining, struct svc_rdma_rw_ctxt *ctxt) { unsigned int sge_no, sge_bytes, page_off, page_no; struct xdr_buf *xdr = info->wi_xdr; struct scatterlist *sg; struct page **page; page_off = info->wi_next_off + xdr->page_base; page_no = page_off >> PAGE_SHIFT; page_off = offset_in_page(page_off); page = xdr->pages + page_no; info->wi_next_off += remaining; sg = ctxt->rw_sg_table.sgl; sge_no = 0; do { sge_bytes = min_t(unsigned int, remaining, PAGE_SIZE - page_off); sg_set_page(sg, *page, sge_bytes, page_off); remaining -= sge_bytes; sg = sg_next(sg); page_off = 0; sge_no++; page++; } while (remaining); ctxt->rw_nents = sge_no; } /* Construct RDMA Write WRs to send a portion of an xdr_buf containing * an RPC Reply. */ static int svc_rdma_build_writes(struct svc_rdma_write_info *info, void (*constructor)(struct svc_rdma_write_info *info, unsigned int len, struct svc_rdma_rw_ctxt *ctxt), unsigned int remaining) { struct svc_rdma_chunk_ctxt *cc = &info->wi_cc; struct svcxprt_rdma *rdma = cc->cc_rdma; struct svc_rdma_rw_ctxt *ctxt; __be32 *seg; int ret; seg = info->wi_segs + info->wi_seg_no * rpcrdma_segment_maxsz; do { unsigned int write_len; u32 seg_length, seg_handle; u64 seg_offset; if (info->wi_seg_no >= info->wi_nsegs) goto out_overflow; seg_handle = be32_to_cpup(seg); seg_length = be32_to_cpup(seg + 1); xdr_decode_hyper(seg + 2, &seg_offset); seg_offset += info->wi_seg_off; write_len = min(remaining, seg_length - info->wi_seg_off); ctxt = svc_rdma_get_rw_ctxt(rdma, (write_len >> PAGE_SHIFT) + 2); if (!ctxt) goto out_noctx; constructor(info, write_len, ctxt); ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp, rdma->sc_port_num, ctxt->rw_sg_table.sgl, ctxt->rw_nents, 0, seg_offset, seg_handle, DMA_TO_DEVICE); if (ret < 0) goto out_initerr; trace_svcrdma_encode_wseg(seg_handle, write_len, seg_offset); list_add(&ctxt->rw_list, &cc->cc_rwctxts); cc->cc_sqecount += ret; if (write_len == seg_length - info->wi_seg_off) { seg += 4; info->wi_seg_no++; info->wi_seg_off = 0; } else { info->wi_seg_off += write_len; } remaining -= write_len; } while (remaining); return 0; out_overflow: dprintk("svcrdma: inadequate space in Write chunk (%u)\n", info->wi_nsegs); return -E2BIG; out_noctx: dprintk("svcrdma: no R/W ctxs available\n"); return -ENOMEM; out_initerr: svc_rdma_put_rw_ctxt(rdma, ctxt); trace_svcrdma_dma_map_rwctx(rdma, ret); return -EIO; } /* Send one of an xdr_buf's kvecs by itself. To send a Reply * chunk, the whole RPC Reply is written back to the client. * This function writes either the head or tail of the xdr_buf * containing the Reply. */ static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info, struct kvec *vec) { info->wi_base = vec->iov_base; return svc_rdma_build_writes(info, svc_rdma_vec_to_sg, vec->iov_len); } /* Send an xdr_buf's page list by itself. A Write chunk is * just the page list. a Reply chunk is the head, page list, * and tail. This function is shared between the two types * of chunk. */ static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info, struct xdr_buf *xdr) { info->wi_xdr = xdr; info->wi_next_off = 0; return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg, xdr->page_len); } /** * svc_rdma_send_write_chunk - Write all segments in a Write chunk * @rdma: controlling RDMA transport * @wr_ch: Write chunk provided by client * @xdr: xdr_buf containing the data payload * * Returns a non-negative number of bytes the chunk consumed, or * %-E2BIG if the payload was larger than the Write chunk, * %-EINVAL if client provided too many segments, * %-ENOMEM if rdma_rw context pool was exhausted, * %-ENOTCONN if posting failed (connection is lost), * %-EIO if rdma_rw initialization failed (DMA mapping, etc). */ int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch, struct xdr_buf *xdr) { struct svc_rdma_write_info *info; int ret; if (!xdr->page_len) return 0; info = svc_rdma_write_info_alloc(rdma, wr_ch); if (!info) return -ENOMEM; ret = svc_rdma_send_xdr_pagelist(info, xdr); if (ret < 0) goto out_err; ret = svc_rdma_post_chunk_ctxt(&info->wi_cc); if (ret < 0) goto out_err; trace_svcrdma_encode_write(xdr->page_len); return xdr->page_len; out_err: svc_rdma_write_info_free(info); return ret; } /** * svc_rdma_send_reply_chunk - Write all segments in the Reply chunk * @rdma: controlling RDMA transport * @rp_ch: Reply chunk provided by client * @writelist: true if client provided a Write list * @xdr: xdr_buf containing an RPC Reply * * Returns a non-negative number of bytes the chunk consumed, or * %-E2BIG if the payload was larger than the Reply chunk, * %-EINVAL if client provided too many segments, * %-ENOMEM if rdma_rw context pool was exhausted, * %-ENOTCONN if posting failed (connection is lost), * %-EIO if rdma_rw initialization failed (DMA mapping, etc). */ int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma, __be32 *rp_ch, bool writelist, struct xdr_buf *xdr) { struct svc_rdma_write_info *info; int consumed, ret; info = svc_rdma_write_info_alloc(rdma, rp_ch); if (!info) return -ENOMEM; ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]); if (ret < 0) goto out_err; consumed = xdr->head[0].iov_len; /* Send the page list in the Reply chunk only if the * client did not provide Write chunks. */ if (!writelist && xdr->page_len) { ret = svc_rdma_send_xdr_pagelist(info, xdr); if (ret < 0) goto out_err; consumed += xdr->page_len; } if (xdr->tail[0].iov_len) { ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]); if (ret < 0) goto out_err; consumed += xdr->tail[0].iov_len; } ret = svc_rdma_post_chunk_ctxt(&info->wi_cc); if (ret < 0) goto out_err; trace_svcrdma_encode_reply(consumed); return consumed; out_err: svc_rdma_write_info_free(info); return ret; } static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info, struct svc_rqst *rqstp, u32 rkey, u32 len, u64 offset) { struct svc_rdma_recv_ctxt *head = info->ri_readctxt; struct svc_rdma_chunk_ctxt *cc = &info->ri_cc; struct svc_rdma_rw_ctxt *ctxt; unsigned int sge_no, seg_len; struct scatterlist *sg; int ret; sge_no = PAGE_ALIGN(info->ri_pageoff + len) >> PAGE_SHIFT; ctxt = svc_rdma_get_rw_ctxt(cc->cc_rdma, sge_no); if (!ctxt) goto out_noctx; ctxt->rw_nents = sge_no; sg = ctxt->rw_sg_table.sgl; for (sge_no = 0; sge_no < ctxt->rw_nents; sge_no++) { seg_len = min_t(unsigned int, len, PAGE_SIZE - info->ri_pageoff); head->rc_arg.pages[info->ri_pageno] = rqstp->rq_pages[info->ri_pageno]; if (!info->ri_pageoff) head->rc_page_count++; sg_set_page(sg, rqstp->rq_pages[info->ri_pageno], seg_len, info->ri_pageoff); sg = sg_next(sg); info->ri_pageoff += seg_len; if (info->ri_pageoff == PAGE_SIZE) { info->ri_pageno++; info->ri_pageoff = 0; } len -= seg_len; /* Safety check */ if (len && &rqstp->rq_pages[info->ri_pageno + 1] > rqstp->rq_page_end) goto out_overrun; } ret = rdma_rw_ctx_init(&ctxt->rw_ctx, cc->cc_rdma->sc_qp, cc->cc_rdma->sc_port_num, ctxt->rw_sg_table.sgl, ctxt->rw_nents, 0, offset, rkey, DMA_FROM_DEVICE); if (ret < 0) goto out_initerr; list_add(&ctxt->rw_list, &cc->cc_rwctxts); cc->cc_sqecount += ret; return 0; out_noctx: dprintk("svcrdma: no R/W ctxs available\n"); return -ENOMEM; out_overrun: dprintk("svcrdma: request overruns rq_pages\n"); return -EINVAL; out_initerr: trace_svcrdma_dma_map_rwctx(cc->cc_rdma, ret); svc_rdma_put_rw_ctxt(cc->cc_rdma, ctxt); return -EIO; } /* Walk the segments in the Read chunk starting at @p and construct * RDMA Read operations to pull the chunk to the server. */ static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp, struct svc_rdma_read_info *info, __be32 *p) { unsigned int i; int ret; ret = -EINVAL; info->ri_chunklen = 0; while (*p++ != xdr_zero && be32_to_cpup(p++) == info->ri_position) { u32 rs_handle, rs_length; u64 rs_offset; rs_handle = be32_to_cpup(p++); rs_length = be32_to_cpup(p++); p = xdr_decode_hyper(p, &rs_offset); ret = svc_rdma_build_read_segment(info, rqstp, rs_handle, rs_length, rs_offset); if (ret < 0) break; trace_svcrdma_encode_rseg(rs_handle, rs_length, rs_offset); info->ri_chunklen += rs_length; } /* Pages under I/O have been copied to head->rc_pages. * Prevent their premature release by svc_xprt_release() . */ for (i = 0; i < info->ri_readctxt->rc_page_count; i++) rqstp->rq_pages[i] = NULL; return ret; } /* Construct RDMA Reads to pull over a normal Read chunk. The chunk * data lands in the page list of head->rc_arg.pages. * * Currently NFSD does not look at the head->rc_arg.tail[0] iovec. * Therefore, XDR round-up of the Read chunk and trailing * inline content must both be added at the end of the pagelist. */ static int svc_rdma_build_normal_read_chunk(struct svc_rqst *rqstp, struct svc_rdma_read_info *info, __be32 *p) { struct svc_rdma_recv_ctxt *head = info->ri_readctxt; int ret; ret = svc_rdma_build_read_chunk(rqstp, info, p); if (ret < 0) goto out; trace_svcrdma_encode_read(info->ri_chunklen, info->ri_position); head->rc_hdr_count = 0; /* Split the Receive buffer between the head and tail * buffers at Read chunk's position. XDR roundup of the * chunk is not included in either the pagelist or in * the tail. */ head->rc_arg.tail[0].iov_base = head->rc_arg.head[0].iov_base + info->ri_position; head->rc_arg.tail[0].iov_len = head->rc_arg.head[0].iov_len - info->ri_position; head->rc_arg.head[0].iov_len = info->ri_position; /* Read chunk may need XDR roundup (see RFC 8166, s. 3.4.5.2). * * If the client already rounded up the chunk length, the * length does not change. Otherwise, the length of the page * list is increased to include XDR round-up. * * Currently these chunks always start at page offset 0, * thus the rounded-up length never crosses a page boundary. */ info->ri_chunklen = XDR_QUADLEN(info->ri_chunklen) << 2; head->rc_arg.page_len = info->ri_chunklen; head->rc_arg.len += info->ri_chunklen; head->rc_arg.buflen += info->ri_chunklen; out: return ret; } /* Construct RDMA Reads to pull over a Position Zero Read chunk. * The start of the data lands in the first page just after * the Transport header, and the rest lands in the page list of * head->rc_arg.pages. * * Assumptions: * - A PZRC has an XDR-aligned length (no implicit round-up). * - There can be no trailing inline content (IOW, we assume * a PZRC is never sent in an RDMA_MSG message, though it's * allowed by spec). */ static int svc_rdma_build_pz_read_chunk(struct svc_rqst *rqstp, struct svc_rdma_read_info *info, __be32 *p) { struct svc_rdma_recv_ctxt *head = info->ri_readctxt; int ret; ret = svc_rdma_build_read_chunk(rqstp, info, p); if (ret < 0) goto out; trace_svcrdma_encode_pzr(info->ri_chunklen); head->rc_arg.len += info->ri_chunklen; head->rc_arg.buflen += info->ri_chunklen; head->rc_hdr_count = 1; head->rc_arg.head[0].iov_base = page_address(head->rc_pages[0]); head->rc_arg.head[0].iov_len = min_t(size_t, PAGE_SIZE, info->ri_chunklen); head->rc_arg.page_len = info->ri_chunklen - head->rc_arg.head[0].iov_len; out: return ret; } /** * svc_rdma_recv_read_chunk - Pull a Read chunk from the client * @rdma: controlling RDMA transport * @rqstp: set of pages to use as Read sink buffers * @head: pages under I/O collect here * @p: pointer to start of Read chunk * * Returns: * %0 if all needed RDMA Reads were posted successfully, * %-EINVAL if client provided too many segments, * %-ENOMEM if rdma_rw context pool was exhausted, * %-ENOTCONN if posting failed (connection is lost), * %-EIO if rdma_rw initialization failed (DMA mapping, etc). * * Assumptions: * - All Read segments in @p have the same Position value. */ int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp, struct svc_rdma_recv_ctxt *head, __be32 *p) { struct svc_rdma_read_info *info; int ret; /* The request (with page list) is constructed in * head->rc_arg. Pages involved with RDMA Read I/O are * transferred there. */ head->rc_arg.head[0] = rqstp->rq_arg.head[0]; head->rc_arg.tail[0] = rqstp->rq_arg.tail[0]; head->rc_arg.pages = head->rc_pages; head->rc_arg.page_base = 0; head->rc_arg.page_len = 0; head->rc_arg.len = rqstp->rq_arg.len; head->rc_arg.buflen = rqstp->rq_arg.buflen; info = svc_rdma_read_info_alloc(rdma); if (!info) return -ENOMEM; info->ri_readctxt = head; info->ri_pageno = 0; info->ri_pageoff = 0; info->ri_position = be32_to_cpup(p + 1); if (info->ri_position) ret = svc_rdma_build_normal_read_chunk(rqstp, info, p); else ret = svc_rdma_build_pz_read_chunk(rqstp, info, p); if (ret < 0) goto out_err; ret = svc_rdma_post_chunk_ctxt(&info->ri_cc); if (ret < 0) goto out_err; return 0; out_err: svc_rdma_read_info_free(info); return ret; }