diff options
Diffstat (limited to 'net/sunrpc/xprtrdma/svc_rdma_recvfrom.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 881 |
1 files changed, 881 insertions, 0 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c new file mode 100644 index 000000000..c6ea2903c --- /dev/null +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -0,0 +1,881 @@ +// 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_recvfrom. This is called from + * svc_recv when the transport indicates there is incoming data to + * be read. "Data Ready" is signaled when an RDMA Receive completes, + * or when a set of RDMA Reads complete. + * + * An svc_rqst is passed in. This structure contains an array of + * free pages (rq_pages) that will contain the incoming RPC message. + * + * Short messages are moved directly into svc_rqst::rq_arg, and + * the RPC Call is ready to be processed by the Upper Layer. + * svc_rdma_recvfrom returns the length of the RPC Call message, + * completing the reception of the RPC Call. + * + * However, when an incoming message has Read chunks, + * svc_rdma_recvfrom must post RDMA Reads to pull the RPC Call's + * data payload from the client. svc_rdma_recvfrom sets up the + * RDMA Reads using pages in svc_rqst::rq_pages, which are + * transferred to an svc_rdma_recv_ctxt for the duration of the + * I/O. svc_rdma_recvfrom then returns zero, since the RPC message + * is still not yet ready. + * + * When the Read chunk payloads have become available on the + * server, "Data Ready" is raised again, and svc_recv calls + * svc_rdma_recvfrom again. This second call may use a different + * svc_rqst than the first one, thus any information that needs + * to be preserved across these two calls is kept in an + * svc_rdma_recv_ctxt. + * + * The second call to svc_rdma_recvfrom performs final assembly + * of the RPC Call message, using the RDMA Read sink pages kept in + * the svc_rdma_recv_ctxt. The xdr_buf is copied from the + * svc_rdma_recv_ctxt to the second svc_rqst. The second call returns + * the length of the completed RPC Call message. + * + * Page Management + * + * Pages under I/O must be transferred from the first svc_rqst to an + * svc_rdma_recv_ctxt before the first svc_rdma_recvfrom call returns. + * + * The first svc_rqst supplies pages for RDMA Reads. These are moved + * from rqstp::rq_pages into ctxt::pages. The consumed elements of + * the rq_pages array are set to NULL and refilled with the first + * svc_rdma_recvfrom call returns. + * + * During the second svc_rdma_recvfrom call, RDMA Read sink pages + * are transferred from the svc_rdma_recv_ctxt to the second svc_rqst + * (see rdma_read_complete() below). + */ + +#include <linux/spinlock.h> +#include <asm/unaligned.h> +#include <rdma/ib_verbs.h> +#include <rdma/rdma_cm.h> + +#include <linux/sunrpc/xdr.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_receive(struct ib_cq *cq, struct ib_wc *wc); + +static inline struct svc_rdma_recv_ctxt * +svc_rdma_next_recv_ctxt(struct list_head *list) +{ + return list_first_entry_or_null(list, struct svc_rdma_recv_ctxt, + rc_list); +} + +static void svc_rdma_recv_cid_init(struct svcxprt_rdma *rdma, + struct rpc_rdma_cid *cid) +{ + cid->ci_queue_id = rdma->sc_rq_cq->res.id; + cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids); +} + +static struct svc_rdma_recv_ctxt * +svc_rdma_recv_ctxt_alloc(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_recv_ctxt *ctxt; + dma_addr_t addr; + void *buffer; + + ctxt = kmalloc(sizeof(*ctxt), 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_FROM_DEVICE); + if (ib_dma_mapping_error(rdma->sc_pd->device, addr)) + goto fail2; + + svc_rdma_recv_cid_init(rdma, &ctxt->rc_cid); + + ctxt->rc_recv_wr.next = NULL; + ctxt->rc_recv_wr.wr_cqe = &ctxt->rc_cqe; + ctxt->rc_recv_wr.sg_list = &ctxt->rc_recv_sge; + ctxt->rc_recv_wr.num_sge = 1; + ctxt->rc_cqe.done = svc_rdma_wc_receive; + ctxt->rc_recv_sge.addr = addr; + ctxt->rc_recv_sge.length = rdma->sc_max_req_size; + ctxt->rc_recv_sge.lkey = rdma->sc_pd->local_dma_lkey; + ctxt->rc_recv_buf = buffer; + ctxt->rc_temp = false; + return ctxt; + +fail2: + kfree(buffer); +fail1: + kfree(ctxt); +fail0: + return NULL; +} + +static void svc_rdma_recv_ctxt_destroy(struct svcxprt_rdma *rdma, + struct svc_rdma_recv_ctxt *ctxt) +{ + ib_dma_unmap_single(rdma->sc_pd->device, ctxt->rc_recv_sge.addr, + ctxt->rc_recv_sge.length, DMA_FROM_DEVICE); + kfree(ctxt->rc_recv_buf); + kfree(ctxt); +} + +/** + * svc_rdma_recv_ctxts_destroy - Release all recv_ctxt's for an xprt + * @rdma: svcxprt_rdma being torn down + * + */ +void svc_rdma_recv_ctxts_destroy(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_recv_ctxt *ctxt; + struct llist_node *node; + + while ((node = llist_del_first(&rdma->sc_recv_ctxts))) { + ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node); + svc_rdma_recv_ctxt_destroy(rdma, ctxt); + } +} + +static struct svc_rdma_recv_ctxt * +svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_recv_ctxt *ctxt; + struct llist_node *node; + + node = llist_del_first(&rdma->sc_recv_ctxts); + if (!node) + goto out_empty; + ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node); + +out: + ctxt->rc_page_count = 0; + ctxt->rc_read_payload_length = 0; + return ctxt; + +out_empty: + ctxt = svc_rdma_recv_ctxt_alloc(rdma); + if (!ctxt) + return NULL; + goto out; +} + +/** + * svc_rdma_recv_ctxt_put - Return recv_ctxt to free list + * @rdma: controlling svcxprt_rdma + * @ctxt: object to return to the free list + * + */ +void svc_rdma_recv_ctxt_put(struct svcxprt_rdma *rdma, + struct svc_rdma_recv_ctxt *ctxt) +{ + unsigned int i; + + for (i = 0; i < ctxt->rc_page_count; i++) + put_page(ctxt->rc_pages[i]); + + if (!ctxt->rc_temp) + llist_add(&ctxt->rc_node, &rdma->sc_recv_ctxts); + else + svc_rdma_recv_ctxt_destroy(rdma, ctxt); +} + +/** + * svc_rdma_release_rqst - Release transport-specific per-rqst resources + * @rqstp: svc_rqst being released + * + * Ensure that the recv_ctxt is released whether or not a Reply + * was sent. For example, the client could close the connection, + * or svc_process could drop an RPC, before the Reply is sent. + */ +void svc_rdma_release_rqst(struct svc_rqst *rqstp) +{ + struct svc_rdma_recv_ctxt *ctxt = rqstp->rq_xprt_ctxt; + struct svc_xprt *xprt = rqstp->rq_xprt; + struct svcxprt_rdma *rdma = + container_of(xprt, struct svcxprt_rdma, sc_xprt); + + rqstp->rq_xprt_ctxt = NULL; + if (ctxt) + svc_rdma_recv_ctxt_put(rdma, ctxt); +} + +static int __svc_rdma_post_recv(struct svcxprt_rdma *rdma, + struct svc_rdma_recv_ctxt *ctxt) +{ + int ret; + + trace_svcrdma_post_recv(ctxt); + ret = ib_post_recv(rdma->sc_qp, &ctxt->rc_recv_wr, NULL); + if (ret) + goto err_post; + return 0; + +err_post: + trace_svcrdma_rq_post_err(rdma, ret); + svc_rdma_recv_ctxt_put(rdma, ctxt); + return ret; +} + +static int svc_rdma_post_recv(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_recv_ctxt *ctxt; + + if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) + return 0; + ctxt = svc_rdma_recv_ctxt_get(rdma); + if (!ctxt) + return -ENOMEM; + return __svc_rdma_post_recv(rdma, ctxt); +} + +/** + * svc_rdma_post_recvs - Post initial set of Recv WRs + * @rdma: fresh svcxprt_rdma + * + * Returns true if successful, otherwise false. + */ +bool svc_rdma_post_recvs(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_recv_ctxt *ctxt; + unsigned int i; + int ret; + + for (i = 0; i < rdma->sc_max_requests; i++) { + ctxt = svc_rdma_recv_ctxt_get(rdma); + if (!ctxt) + return false; + ctxt->rc_temp = true; + ret = __svc_rdma_post_recv(rdma, ctxt); + if (ret) + return false; + } + return true; +} + +/** + * svc_rdma_wc_receive - Invoked by RDMA provider for each polled Receive WC + * @cq: Completion Queue context + * @wc: Work Completion object + * + * NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that + * the Receive completion handler could be running. + */ +static void svc_rdma_wc_receive(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_recv_ctxt *ctxt; + + /* WARNING: Only wc->wr_cqe and wc->status are reliable */ + ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe); + + trace_svcrdma_wc_receive(wc, &ctxt->rc_cid); + if (wc->status != IB_WC_SUCCESS) + goto flushed; + + if (svc_rdma_post_recv(rdma)) + goto post_err; + + /* All wc fields are now known to be valid */ + ctxt->rc_byte_len = wc->byte_len; + ib_dma_sync_single_for_cpu(rdma->sc_pd->device, + ctxt->rc_recv_sge.addr, + wc->byte_len, DMA_FROM_DEVICE); + + spin_lock(&rdma->sc_rq_dto_lock); + list_add_tail(&ctxt->rc_list, &rdma->sc_rq_dto_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); + if (!test_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags)) + svc_xprt_enqueue(&rdma->sc_xprt); + return; + +flushed: +post_err: + svc_rdma_recv_ctxt_put(rdma, ctxt); + set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); + svc_xprt_enqueue(&rdma->sc_xprt); +} + +/** + * svc_rdma_flush_recv_queues - Drain pending Receive work + * @rdma: svcxprt_rdma being shut down + * + */ +void svc_rdma_flush_recv_queues(struct svcxprt_rdma *rdma) +{ + struct svc_rdma_recv_ctxt *ctxt; + + while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_read_complete_q))) { + list_del(&ctxt->rc_list); + svc_rdma_recv_ctxt_put(rdma, ctxt); + } + while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_rq_dto_q))) { + list_del(&ctxt->rc_list); + svc_rdma_recv_ctxt_put(rdma, ctxt); + } +} + +static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp, + struct svc_rdma_recv_ctxt *ctxt) +{ + struct xdr_buf *arg = &rqstp->rq_arg; + + arg->head[0].iov_base = ctxt->rc_recv_buf; + arg->head[0].iov_len = ctxt->rc_byte_len; + arg->tail[0].iov_base = NULL; + arg->tail[0].iov_len = 0; + arg->page_len = 0; + arg->page_base = 0; + arg->buflen = ctxt->rc_byte_len; + arg->len = ctxt->rc_byte_len; +} + +/* This accommodates the largest possible Write chunk. + */ +#define MAX_BYTES_WRITE_CHUNK ((u32)(RPCSVC_MAXPAGES << PAGE_SHIFT)) + +/* This accommodates the largest possible Position-Zero + * Read chunk or Reply chunk. + */ +#define MAX_BYTES_SPECIAL_CHUNK ((u32)((RPCSVC_MAXPAGES + 2) << PAGE_SHIFT)) + +/* Sanity check the Read list. + * + * Implementation limits: + * - This implementation supports only one Read chunk. + * + * Sanity checks: + * - Read list does not overflow Receive buffer. + * - Segment size limited by largest NFS data payload. + * + * The segment count is limited to how many segments can + * fit in the transport header without overflowing the + * buffer. That's about 40 Read segments for a 1KB inline + * threshold. + * + * Return values: + * %true: Read list is valid. @rctxt's xdr_stream is updated + * to point to the first byte past the Read list. + * %false: Read list is corrupt. @rctxt's xdr_stream is left + * in an unknown state. + */ +static bool xdr_check_read_list(struct svc_rdma_recv_ctxt *rctxt) +{ + u32 position, len; + bool first; + __be32 *p; + + p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); + if (!p) + return false; + + len = 0; + first = true; + while (xdr_item_is_present(p)) { + p = xdr_inline_decode(&rctxt->rc_stream, + rpcrdma_readseg_maxsz * sizeof(*p)); + if (!p) + return false; + + if (first) { + position = be32_to_cpup(p); + first = false; + } else if (be32_to_cpup(p) != position) { + return false; + } + p += 2; + len += be32_to_cpup(p); + + p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); + if (!p) + return false; + } + return len <= MAX_BYTES_SPECIAL_CHUNK; +} + +/* The segment count is limited to how many segments can + * fit in the transport header without overflowing the + * buffer. That's about 60 Write segments for a 1KB inline + * threshold. + */ +static bool xdr_check_write_chunk(struct svc_rdma_recv_ctxt *rctxt, u32 maxlen) +{ + u32 i, segcount, total; + __be32 *p; + + p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); + if (!p) + return false; + segcount = be32_to_cpup(p); + + total = 0; + for (i = 0; i < segcount; i++) { + u32 handle, length; + u64 offset; + + p = xdr_inline_decode(&rctxt->rc_stream, + rpcrdma_segment_maxsz * sizeof(*p)); + if (!p) + return false; + + xdr_decode_rdma_segment(p, &handle, &length, &offset); + trace_svcrdma_decode_wseg(handle, length, offset); + + total += length; + } + return total <= maxlen; +} + +/* Sanity check the Write list. + * + * Implementation limits: + * - This implementation currently supports only one Write chunk. + * + * Sanity checks: + * - Write list does not overflow Receive buffer. + * - Chunk size limited by largest NFS data payload. + * + * Return values: + * %true: Write list is valid. @rctxt's xdr_stream is updated + * to point to the first byte past the Write list. + * %false: Write list is corrupt. @rctxt's xdr_stream is left + * in an unknown state. + */ +static bool xdr_check_write_list(struct svc_rdma_recv_ctxt *rctxt) +{ + u32 chcount = 0; + __be32 *p; + + p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); + if (!p) + return false; + rctxt->rc_write_list = p; + while (xdr_item_is_present(p)) { + if (!xdr_check_write_chunk(rctxt, MAX_BYTES_WRITE_CHUNK)) + return false; + ++chcount; + p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); + if (!p) + return false; + } + if (!chcount) + rctxt->rc_write_list = NULL; + return chcount < 2; +} + +/* Sanity check the Reply chunk. + * + * Sanity checks: + * - Reply chunk does not overflow Receive buffer. + * - Chunk size limited by largest NFS data payload. + * + * Return values: + * %true: Reply chunk is valid. @rctxt's xdr_stream is updated + * to point to the first byte past the Reply chunk. + * %false: Reply chunk is corrupt. @rctxt's xdr_stream is left + * in an unknown state. + */ +static bool xdr_check_reply_chunk(struct svc_rdma_recv_ctxt *rctxt) +{ + __be32 *p; + + p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); + if (!p) + return false; + rctxt->rc_reply_chunk = NULL; + if (xdr_item_is_present(p)) { + if (!xdr_check_write_chunk(rctxt, MAX_BYTES_SPECIAL_CHUNK)) + return false; + rctxt->rc_reply_chunk = p; + } + return true; +} + +/* RPC-over-RDMA Version One private extension: Remote Invalidation. + * Responder's choice: requester signals it can handle Send With + * Invalidate, and responder chooses one R_key to invalidate. + * + * If there is exactly one distinct R_key in the received transport + * header, set rc_inv_rkey to that R_key. Otherwise, set it to zero. + * + * Perform this operation while the received transport header is + * still in the CPU cache. + */ +static void svc_rdma_get_inv_rkey(struct svcxprt_rdma *rdma, + struct svc_rdma_recv_ctxt *ctxt) +{ + __be32 inv_rkey, *p; + u32 i, segcount; + + ctxt->rc_inv_rkey = 0; + + if (!rdma->sc_snd_w_inv) + return; + + inv_rkey = xdr_zero; + p = ctxt->rc_recv_buf; + p += rpcrdma_fixed_maxsz; + + /* Read list */ + while (xdr_item_is_present(p++)) { + p++; /* position */ + if (inv_rkey == xdr_zero) + inv_rkey = *p; + else if (inv_rkey != *p) + return; + p += 4; + } + + /* Write list */ + while (xdr_item_is_present(p++)) { + segcount = be32_to_cpup(p++); + for (i = 0; i < segcount; i++) { + if (inv_rkey == xdr_zero) + inv_rkey = *p; + else if (inv_rkey != *p) + return; + p += 4; + } + } + + /* Reply chunk */ + if (xdr_item_is_present(p++)) { + segcount = be32_to_cpup(p++); + for (i = 0; i < segcount; i++) { + if (inv_rkey == xdr_zero) + inv_rkey = *p; + else if (inv_rkey != *p) + return; + p += 4; + } + } + + ctxt->rc_inv_rkey = be32_to_cpu(inv_rkey); +} + +/** + * svc_rdma_xdr_decode_req - Decode the transport header + * @rq_arg: xdr_buf containing ingress RPC/RDMA message + * @rctxt: state of decoding + * + * On entry, xdr->head[0].iov_base points to first byte of the + * RPC-over-RDMA transport header. + * + * On successful exit, head[0] points to first byte past the + * RPC-over-RDMA header. For RDMA_MSG, this is the RPC message. + * + * The length of the RPC-over-RDMA header is returned. + * + * Assumptions: + * - The transport header is entirely contained in the head iovec. + */ +static int svc_rdma_xdr_decode_req(struct xdr_buf *rq_arg, + struct svc_rdma_recv_ctxt *rctxt) +{ + __be32 *p, *rdma_argp; + unsigned int hdr_len; + + rdma_argp = rq_arg->head[0].iov_base; + xdr_init_decode(&rctxt->rc_stream, rq_arg, rdma_argp, NULL); + + p = xdr_inline_decode(&rctxt->rc_stream, + rpcrdma_fixed_maxsz * sizeof(*p)); + if (unlikely(!p)) + goto out_short; + p++; + if (*p != rpcrdma_version) + goto out_version; + p += 2; + switch (*p) { + case rdma_msg: + break; + case rdma_nomsg: + break; + case rdma_done: + goto out_drop; + case rdma_error: + goto out_drop; + default: + goto out_proc; + } + + if (!xdr_check_read_list(rctxt)) + goto out_inval; + if (!xdr_check_write_list(rctxt)) + goto out_inval; + if (!xdr_check_reply_chunk(rctxt)) + goto out_inval; + + rq_arg->head[0].iov_base = rctxt->rc_stream.p; + hdr_len = xdr_stream_pos(&rctxt->rc_stream); + rq_arg->head[0].iov_len -= hdr_len; + rq_arg->len -= hdr_len; + trace_svcrdma_decode_rqst(rctxt, rdma_argp, hdr_len); + return hdr_len; + +out_short: + trace_svcrdma_decode_short_err(rctxt, rq_arg->len); + return -EINVAL; + +out_version: + trace_svcrdma_decode_badvers_err(rctxt, rdma_argp); + return -EPROTONOSUPPORT; + +out_drop: + trace_svcrdma_decode_drop_err(rctxt, rdma_argp); + return 0; + +out_proc: + trace_svcrdma_decode_badproc_err(rctxt, rdma_argp); + return -EINVAL; + +out_inval: + trace_svcrdma_decode_parse_err(rctxt, rdma_argp); + return -EINVAL; +} + +static void rdma_read_complete(struct svc_rqst *rqstp, + struct svc_rdma_recv_ctxt *head) +{ + int page_no; + + /* Move Read chunk pages to rqstp so that they will be released + * when svc_process is done with them. + */ + for (page_no = 0; page_no < head->rc_page_count; page_no++) { + put_page(rqstp->rq_pages[page_no]); + rqstp->rq_pages[page_no] = head->rc_pages[page_no]; + } + head->rc_page_count = 0; + + /* Point rq_arg.pages past header */ + rqstp->rq_arg.pages = &rqstp->rq_pages[head->rc_hdr_count]; + rqstp->rq_arg.page_len = head->rc_arg.page_len; + + /* rq_respages starts after the last arg page */ + rqstp->rq_respages = &rqstp->rq_pages[page_no]; + rqstp->rq_next_page = rqstp->rq_respages + 1; + + /* Rebuild rq_arg head and tail. */ + rqstp->rq_arg.head[0] = head->rc_arg.head[0]; + rqstp->rq_arg.tail[0] = head->rc_arg.tail[0]; + rqstp->rq_arg.len = head->rc_arg.len; + rqstp->rq_arg.buflen = head->rc_arg.buflen; +} + +static void svc_rdma_send_error(struct svcxprt_rdma *rdma, + struct svc_rdma_recv_ctxt *rctxt, + int status) +{ + struct svc_rdma_send_ctxt *sctxt; + + sctxt = svc_rdma_send_ctxt_get(rdma); + if (!sctxt) + return; + svc_rdma_send_error_msg(rdma, sctxt, rctxt, status); +} + +/* By convention, backchannel calls arrive via rdma_msg type + * messages, and never populate the chunk lists. This makes + * the RPC/RDMA header small and fixed in size, so it is + * straightforward to check the RPC header's direction field. + */ +static bool svc_rdma_is_backchannel_reply(struct svc_xprt *xprt, + __be32 *rdma_resp) +{ + __be32 *p; + + if (!xprt->xpt_bc_xprt) + return false; + + p = rdma_resp + 3; + if (*p++ != rdma_msg) + return false; + + if (*p++ != xdr_zero) + return false; + if (*p++ != xdr_zero) + return false; + if (*p++ != xdr_zero) + return false; + + /* XID sanity */ + if (*p++ != *rdma_resp) + return false; + /* call direction */ + if (*p == cpu_to_be32(RPC_CALL)) + return false; + + return true; +} + +/** + * svc_rdma_recvfrom - Receive an RPC call + * @rqstp: request structure into which to receive an RPC Call + * + * Returns: + * The positive number of bytes in the RPC Call message, + * %0 if there were no Calls ready to return, + * %-EINVAL if the Read chunk data is too large, + * %-ENOMEM if rdma_rw context pool was exhausted, + * %-ENOTCONN if posting failed (connection is lost), + * %-EIO if rdma_rw initialization failed (DMA mapping, etc). + * + * Called in a loop when XPT_DATA is set. XPT_DATA is cleared only + * when there are no remaining ctxt's to process. + * + * The next ctxt is removed from the "receive" lists. + * + * - If the ctxt completes a Read, then finish assembling the Call + * message and return the number of bytes in the message. + * + * - If the ctxt completes a Receive, then construct the Call + * message from the contents of the Receive buffer. + * + * - If there are no Read chunks in this message, then finish + * assembling the Call message and return the number of bytes + * in the message. + * + * - If there are Read chunks in this message, post Read WRs to + * pull that payload and return 0. + */ +int svc_rdma_recvfrom(struct svc_rqst *rqstp) +{ + struct svc_xprt *xprt = rqstp->rq_xprt; + struct svcxprt_rdma *rdma_xprt = + container_of(xprt, struct svcxprt_rdma, sc_xprt); + struct svc_rdma_recv_ctxt *ctxt; + __be32 *p; + int ret; + + rqstp->rq_xprt_ctxt = NULL; + + spin_lock(&rdma_xprt->sc_rq_dto_lock); + ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_read_complete_q); + if (ctxt) { + list_del(&ctxt->rc_list); + spin_unlock(&rdma_xprt->sc_rq_dto_lock); + rdma_read_complete(rqstp, ctxt); + goto complete; + } + ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_rq_dto_q); + if (!ctxt) { + /* No new incoming requests, terminate the loop */ + clear_bit(XPT_DATA, &xprt->xpt_flags); + spin_unlock(&rdma_xprt->sc_rq_dto_lock); + return 0; + } + list_del(&ctxt->rc_list); + spin_unlock(&rdma_xprt->sc_rq_dto_lock); + + atomic_inc(&rdma_stat_recv); + + svc_rdma_build_arg_xdr(rqstp, ctxt); + + /* Prevent svc_xprt_release from releasing pages in rq_pages + * if we return 0 or an error. + */ + rqstp->rq_respages = rqstp->rq_pages; + rqstp->rq_next_page = rqstp->rq_respages; + + p = (__be32 *)rqstp->rq_arg.head[0].iov_base; + ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg, ctxt); + if (ret < 0) + goto out_err; + if (ret == 0) + goto out_drop; + rqstp->rq_xprt_hlen = ret; + + if (svc_rdma_is_backchannel_reply(xprt, p)) + goto out_backchannel; + + svc_rdma_get_inv_rkey(rdma_xprt, ctxt); + + p += rpcrdma_fixed_maxsz; + if (*p != xdr_zero) + goto out_readchunk; + +complete: + rqstp->rq_xprt_ctxt = ctxt; + rqstp->rq_prot = IPPROTO_MAX; + svc_xprt_copy_addrs(rqstp, xprt); + return rqstp->rq_arg.len; + +out_readchunk: + ret = svc_rdma_recv_read_chunk(rdma_xprt, rqstp, ctxt, p); + if (ret < 0) + goto out_postfail; + return 0; + +out_err: + svc_rdma_send_error(rdma_xprt, ctxt, ret); + svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); + return 0; + +out_postfail: + if (ret == -EINVAL) + svc_rdma_send_error(rdma_xprt, ctxt, ret); + svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); + return ret; + +out_backchannel: + svc_rdma_handle_bc_reply(rqstp, ctxt); +out_drop: + svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); + return 0; +} |