diff options
Diffstat (limited to 'net/sunrpc/xprtrdma/svc_rdma_rw.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_rw.c | 877 |
1 files changed, 877 insertions, 0 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c new file mode 100644 index 000000000..22f135263 --- /dev/null +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c @@ -0,0 +1,877 @@ +// 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 <rdma/rw.h> + +#include <linux/sunrpc/rpc_rdma.h> +#include <linux/sunrpc/svc_rdma.h> +#include <linux/sunrpc/debug.h> + +#include "xprt_rdma.h" +#include <trace/events/rpcrdma.h> + +#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(sizeof(*ctxt) + + SG_CHUNK_SIZE * sizeof(struct scatterlist), + 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)) { + 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, true); + + 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); + if (wc->status != IB_WC_WR_FLUSH_ERR) + pr_err("svcrdma: write ctx: %s (%u/0x%x)\n", + ib_wc_status_msg(wc->status), + wc->status, wc->vendor_err); + } + + 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); + if (wc->status != IB_WC_WR_FLUSH_ERR) + pr_err("svcrdma: read ctx: %s (%u/0x%x)\n", + ib_wc_status_msg(wc->status), + wc->status, wc->vendor_err); + 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); + spin_unlock(&rdma->sc_rq_dto_lock); + + set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags); + 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); + 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); + + trace_svcrdma_sq_post_err(rdma, ret); + 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) +{ + 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; + } + + 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; +} + +/* Pages under I/O have been copied to head->rc_pages. Ensure they + * are not released by svc_xprt_release() until the I/O is complete. + * + * This has to be done after all Read WRs are constructed to properly + * handle a page that is part of I/O on behalf of two different RDMA + * segments. + * + * Do this only if I/O has been posted. Otherwise, we do indeed want + * svc_xprt_release() to clean things up properly. + */ +static void svc_rdma_save_io_pages(struct svc_rqst *rqstp, + const unsigned int start, + const unsigned int num_pages) +{ + unsigned int i; + + for (i = start; i < num_pages + start; i++) + rqstp->rq_pages[i] = NULL; +} + +/** + * 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; + svc_rdma_save_io_pages(rqstp, 0, head->rc_page_count); + return 0; + +out_err: + svc_rdma_read_info_free(info); + return ret; +} |