From f13193f50b64e2e0c87706b838d6b9895626a892 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sun, 9 Apr 2017 13:06:16 -0400 Subject: svcrdma: Introduce local rdma_rw API helpers The plan is to replace the local bespoke code that constructs and posts RDMA Read and Write Work Requests with calls to the rdma_rw API. This shares code with other RDMA-enabled ULPs that manages the gory details of buffer registration and posting Work Requests. Some design notes: o The structure of RPC-over-RDMA transport headers is flexible, allowing multiple segments per Reply with arbitrary alignment, each with a unique R_key. Write and Send WRs continue to be built and posted in separate code paths. However, one whole chunk (with one or more RDMA segments apiece) gets exactly one ib_post_send and one work completion. o svc_xprt reference counting is modified, since a chain of rdma_rw_ctx structs generates one completion, no matter how many Write WRs are posted. o The current code builds the transport header as it is construct- ing Write WRs. I've replaced that with marshaling of transport header data items in a separate step. This is because the exact structure of client-provided segments may not align with the components of the server's reply xdr_buf, or the pages in the page list. Thus parts of each client-provided segment may be written at different points in the send path. Signed-off-by: Chuck Lever Signed-off-by: J. Bruce Fields --- net/sunrpc/Kconfig | 1 + net/sunrpc/xprtrdma/Makefile | 2 +- net/sunrpc/xprtrdma/svc_rdma_rw.c | 512 +++++++++++++++++++++++++++++++ net/sunrpc/xprtrdma/svc_rdma_transport.c | 4 + 4 files changed, 518 insertions(+), 1 deletion(-) create mode 100644 net/sunrpc/xprtrdma/svc_rdma_rw.c (limited to 'net') diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig index 04ce2c0b660e..ac09ca803296 100644 --- a/net/sunrpc/Kconfig +++ b/net/sunrpc/Kconfig @@ -52,6 +52,7 @@ config SUNRPC_XPRT_RDMA tristate "RPC-over-RDMA transport" depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS default SUNRPC && INFINIBAND + select SG_POOL help This option allows the NFS client and server to use RDMA transports (InfiniBand, iWARP, or RoCE). diff --git a/net/sunrpc/xprtrdma/Makefile b/net/sunrpc/xprtrdma/Makefile index ef19fa42c50f..c1ae8142ab73 100644 --- a/net/sunrpc/xprtrdma/Makefile +++ b/net/sunrpc/xprtrdma/Makefile @@ -4,5 +4,5 @@ rpcrdma-y := transport.o rpc_rdma.o verbs.o \ fmr_ops.o frwr_ops.o \ svc_rdma.o svc_rdma_backchannel.o svc_rdma_transport.o \ svc_rdma_marshal.o svc_rdma_sendto.o svc_rdma_recvfrom.o \ - module.o + svc_rdma_rw.o module.o rpcrdma-$(CONFIG_SUNRPC_BACKCHANNEL) += backchannel.o diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c new file mode 100644 index 000000000000..0cf620277693 --- /dev/null +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c @@ -0,0 +1,512 @@ +/* + * Copyright (c) 2016 Oracle. All rights reserved. + * + * Use the core R/W API to move RPC-over-RDMA Read and Write chunks. + */ + +#include +#include +#include + +#include + +#define RPCDBG_FACILITY RPCDBG_SVCXPRT + +/* 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; + enum dma_data_direction cc_dir; +}; + +static void svc_rdma_cc_init(struct svcxprt_rdma *rdma, + struct svc_rdma_chunk_ctxt *cc, + enum dma_data_direction dir) +{ + cc->cc_rdma = rdma; + svc_xprt_get(&rdma->sc_xprt); + + INIT_LIST_HEAD(&cc->cc_rwctxts); + cc->cc_sqecount = 0; + cc->cc_dir = dir; +} + +static void svc_rdma_cc_release(struct svc_rdma_chunk_ctxt *cc) +{ + 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, cc->cc_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, DMA_TO_DEVICE); + return info; +} + +static void svc_rdma_write_info_free(struct svc_rdma_write_info *info) +{ + svc_rdma_cc_release(&info->wi_cc); + 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); + + 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); +} + +/* 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, *bad_wr; + struct list_head *tmp; + struct ib_cqe *cqe; + int ret; + + 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; + } + + atomic_inc(&rdma_stat_sq_starve); + atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail); + wait_event(rdma->sc_send_wait, + atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount); + } while (1); + + pr_err("svcrdma: ib_post_send failed (%d)\n", 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_MASK; + page_no = (info->wi_next_off + xdr->page_base) >> PAGE_SHIFT; + 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; + + cc->cc_cqe.done = svc_rdma_write_done; + 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; + + 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); + pr_err("svcrdma: failed to map pagelist (%d)\n", 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, + * %-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; + 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, + * %-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; + return consumed; + +out_err: + svc_rdma_write_info_free(info); + return ret; +} diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c index e1097cc6d1eb..b25c50992a95 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c @@ -561,6 +561,7 @@ static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv, INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q); INIT_LIST_HEAD(&cma_xprt->sc_frmr_q); INIT_LIST_HEAD(&cma_xprt->sc_ctxts); + INIT_LIST_HEAD(&cma_xprt->sc_rw_ctxts); INIT_LIST_HEAD(&cma_xprt->sc_maps); init_waitqueue_head(&cma_xprt->sc_send_wait); @@ -568,6 +569,7 @@ static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv, spin_lock_init(&cma_xprt->sc_rq_dto_lock); spin_lock_init(&cma_xprt->sc_frmr_q_lock); spin_lock_init(&cma_xprt->sc_ctxt_lock); + spin_lock_init(&cma_xprt->sc_rw_ctxt_lock); spin_lock_init(&cma_xprt->sc_map_lock); /* @@ -999,6 +1001,7 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt) newxprt, newxprt->sc_cm_id); dev = newxprt->sc_cm_id->device; + newxprt->sc_port_num = newxprt->sc_cm_id->port_num; /* Qualify the transport resource defaults with the * capabilities of this particular device */ @@ -1248,6 +1251,7 @@ static void __svc_rdma_free(struct work_struct *work) } rdma_dealloc_frmr_q(rdma); + svc_rdma_destroy_rw_ctxts(rdma); svc_rdma_destroy_ctxts(rdma); svc_rdma_destroy_maps(rdma); -- cgit v1.2.1