1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2016-2018 Oracle. All rights reserved.
5 * Use the core R/W API to move RPC-over-RDMA Read and Write chunks.
10 #include <linux/sunrpc/rpc_rdma.h>
11 #include <linux/sunrpc/svc_rdma.h>
12 #include <linux/sunrpc/debug.h>
14 #include "xprt_rdma.h"
15 #include <trace/events/rpcrdma.h>
17 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
19 static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc);
20 static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc);
22 /* Each R/W context contains state for one chain of RDMA Read or
23 * Write Work Requests.
25 * Each WR chain handles a single contiguous server-side buffer,
26 * because scatterlist entries after the first have to start on
27 * page alignment. xdr_buf iovecs cannot guarantee alignment.
29 * Each WR chain handles only one R_key. Each RPC-over-RDMA segment
30 * from a client may contain a unique R_key, so each WR chain moves
31 * up to one segment at a time.
33 * The scatterlist makes this data structure over 4KB in size. To
34 * make it less likely to fail, and to handle the allocation for
35 * smaller I/O requests without disabling bottom-halves, these
36 * contexts are created on demand, but cached and reused until the
37 * controlling svcxprt_rdma is destroyed.
39 struct svc_rdma_rw_ctxt {
40 struct list_head rw_list;
41 struct rdma_rw_ctx rw_ctx;
43 struct sg_table rw_sg_table;
44 struct scatterlist rw_first_sgl[0];
47 static inline struct svc_rdma_rw_ctxt *
48 svc_rdma_next_ctxt(struct list_head *list)
50 return list_first_entry_or_null(list, struct svc_rdma_rw_ctxt,
54 static struct svc_rdma_rw_ctxt *
55 svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
57 struct svc_rdma_rw_ctxt *ctxt;
59 spin_lock(&rdma->sc_rw_ctxt_lock);
61 ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts);
63 list_del(&ctxt->rw_list);
64 spin_unlock(&rdma->sc_rw_ctxt_lock);
66 spin_unlock(&rdma->sc_rw_ctxt_lock);
67 ctxt = kmalloc(sizeof(*ctxt) +
68 SG_CHUNK_SIZE * sizeof(struct scatterlist),
72 INIT_LIST_HEAD(&ctxt->rw_list);
75 ctxt->rw_sg_table.sgl = ctxt->rw_first_sgl;
76 if (sg_alloc_table_chained(&ctxt->rw_sg_table, sges,
77 ctxt->rw_sg_table.sgl)) {
85 static void svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma,
86 struct svc_rdma_rw_ctxt *ctxt)
88 sg_free_table_chained(&ctxt->rw_sg_table, true);
90 spin_lock(&rdma->sc_rw_ctxt_lock);
91 list_add(&ctxt->rw_list, &rdma->sc_rw_ctxts);
92 spin_unlock(&rdma->sc_rw_ctxt_lock);
96 * svc_rdma_destroy_rw_ctxts - Free accumulated R/W contexts
97 * @rdma: transport about to be destroyed
100 void svc_rdma_destroy_rw_ctxts(struct svcxprt_rdma *rdma)
102 struct svc_rdma_rw_ctxt *ctxt;
104 while ((ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts)) != NULL) {
105 list_del(&ctxt->rw_list);
110 /* A chunk context tracks all I/O for moving one Read or Write
111 * chunk. This is a a set of rdma_rw's that handle data movement
112 * for all segments of one chunk.
114 * These are small, acquired with a single allocator call, and
115 * no more than one is needed per chunk. They are allocated on
116 * demand, and not cached.
118 struct svc_rdma_chunk_ctxt {
119 struct ib_cqe cc_cqe;
120 struct svcxprt_rdma *cc_rdma;
121 struct list_head cc_rwctxts;
125 static void svc_rdma_cc_init(struct svcxprt_rdma *rdma,
126 struct svc_rdma_chunk_ctxt *cc)
129 svc_xprt_get(&rdma->sc_xprt);
131 INIT_LIST_HEAD(&cc->cc_rwctxts);
135 static void svc_rdma_cc_release(struct svc_rdma_chunk_ctxt *cc,
136 enum dma_data_direction dir)
138 struct svcxprt_rdma *rdma = cc->cc_rdma;
139 struct svc_rdma_rw_ctxt *ctxt;
141 while ((ctxt = svc_rdma_next_ctxt(&cc->cc_rwctxts)) != NULL) {
142 list_del(&ctxt->rw_list);
144 rdma_rw_ctx_destroy(&ctxt->rw_ctx, rdma->sc_qp,
145 rdma->sc_port_num, ctxt->rw_sg_table.sgl,
146 ctxt->rw_nents, dir);
147 svc_rdma_put_rw_ctxt(rdma, ctxt);
149 svc_xprt_put(&rdma->sc_xprt);
152 /* State for sending a Write or Reply chunk.
153 * - Tracks progress of writing one chunk over all its segments
154 * - Stores arguments for the SGL constructor functions
156 struct svc_rdma_write_info {
157 /* write state of this chunk */
158 unsigned int wi_seg_off;
159 unsigned int wi_seg_no;
160 unsigned int wi_nsegs;
163 /* SGL constructor arguments */
164 struct xdr_buf *wi_xdr;
165 unsigned char *wi_base;
166 unsigned int wi_next_off;
168 struct svc_rdma_chunk_ctxt wi_cc;
171 static struct svc_rdma_write_info *
172 svc_rdma_write_info_alloc(struct svcxprt_rdma *rdma, __be32 *chunk)
174 struct svc_rdma_write_info *info;
176 info = kmalloc(sizeof(*info), GFP_KERNEL);
180 info->wi_seg_off = 0;
182 info->wi_nsegs = be32_to_cpup(++chunk);
183 info->wi_segs = ++chunk;
184 svc_rdma_cc_init(rdma, &info->wi_cc);
185 info->wi_cc.cc_cqe.done = svc_rdma_write_done;
189 static void svc_rdma_write_info_free(struct svc_rdma_write_info *info)
191 svc_rdma_cc_release(&info->wi_cc, DMA_TO_DEVICE);
196 * svc_rdma_write_done - Write chunk completion
197 * @cq: controlling Completion Queue
198 * @wc: Work Completion
200 * Pages under I/O are freed by a subsequent Send completion.
202 static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc)
204 struct ib_cqe *cqe = wc->wr_cqe;
205 struct svc_rdma_chunk_ctxt *cc =
206 container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe);
207 struct svcxprt_rdma *rdma = cc->cc_rdma;
208 struct svc_rdma_write_info *info =
209 container_of(cc, struct svc_rdma_write_info, wi_cc);
211 trace_svcrdma_wc_write(wc);
213 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
214 wake_up(&rdma->sc_send_wait);
216 if (unlikely(wc->status != IB_WC_SUCCESS)) {
217 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
218 if (wc->status != IB_WC_WR_FLUSH_ERR)
219 pr_err("svcrdma: write ctx: %s (%u/0x%x)\n",
220 ib_wc_status_msg(wc->status),
221 wc->status, wc->vendor_err);
224 svc_rdma_write_info_free(info);
227 /* State for pulling a Read chunk.
229 struct svc_rdma_read_info {
230 struct svc_rdma_recv_ctxt *ri_readctxt;
231 unsigned int ri_position;
232 unsigned int ri_pageno;
233 unsigned int ri_pageoff;
234 unsigned int ri_chunklen;
236 struct svc_rdma_chunk_ctxt ri_cc;
239 static struct svc_rdma_read_info *
240 svc_rdma_read_info_alloc(struct svcxprt_rdma *rdma)
242 struct svc_rdma_read_info *info;
244 info = kmalloc(sizeof(*info), GFP_KERNEL);
248 svc_rdma_cc_init(rdma, &info->ri_cc);
249 info->ri_cc.cc_cqe.done = svc_rdma_wc_read_done;
253 static void svc_rdma_read_info_free(struct svc_rdma_read_info *info)
255 svc_rdma_cc_release(&info->ri_cc, DMA_FROM_DEVICE);
260 * svc_rdma_wc_read_done - Handle completion of an RDMA Read ctx
261 * @cq: controlling Completion Queue
262 * @wc: Work Completion
265 static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc)
267 struct ib_cqe *cqe = wc->wr_cqe;
268 struct svc_rdma_chunk_ctxt *cc =
269 container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe);
270 struct svcxprt_rdma *rdma = cc->cc_rdma;
271 struct svc_rdma_read_info *info =
272 container_of(cc, struct svc_rdma_read_info, ri_cc);
274 trace_svcrdma_wc_read(wc);
276 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
277 wake_up(&rdma->sc_send_wait);
279 if (unlikely(wc->status != IB_WC_SUCCESS)) {
280 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
281 if (wc->status != IB_WC_WR_FLUSH_ERR)
282 pr_err("svcrdma: read ctx: %s (%u/0x%x)\n",
283 ib_wc_status_msg(wc->status),
284 wc->status, wc->vendor_err);
285 svc_rdma_recv_ctxt_put(rdma, info->ri_readctxt);
287 spin_lock(&rdma->sc_rq_dto_lock);
288 list_add_tail(&info->ri_readctxt->rc_list,
289 &rdma->sc_read_complete_q);
290 spin_unlock(&rdma->sc_rq_dto_lock);
292 set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags);
293 svc_xprt_enqueue(&rdma->sc_xprt);
296 svc_rdma_read_info_free(info);
299 /* This function sleeps when the transport's Send Queue is congested.
302 * - If ib_post_send() succeeds, only one completion is expected,
303 * even if one or more WRs are flushed. This is true when posting
304 * an rdma_rw_ctx or when posting a single signaled WR.
306 static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc)
308 struct svcxprt_rdma *rdma = cc->cc_rdma;
309 struct svc_xprt *xprt = &rdma->sc_xprt;
310 struct ib_send_wr *first_wr;
311 const struct ib_send_wr *bad_wr;
312 struct list_head *tmp;
316 if (cc->cc_sqecount > rdma->sc_sq_depth)
321 list_for_each(tmp, &cc->cc_rwctxts) {
322 struct svc_rdma_rw_ctxt *ctxt;
324 ctxt = list_entry(tmp, struct svc_rdma_rw_ctxt, rw_list);
325 first_wr = rdma_rw_ctx_wrs(&ctxt->rw_ctx, rdma->sc_qp,
326 rdma->sc_port_num, cqe, first_wr);
331 if (atomic_sub_return(cc->cc_sqecount,
332 &rdma->sc_sq_avail) > 0) {
333 ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr);
334 trace_svcrdma_post_rw(&cc->cc_cqe,
335 cc->cc_sqecount, ret);
341 trace_svcrdma_sq_full(rdma);
342 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
343 wait_event(rdma->sc_send_wait,
344 atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount);
345 trace_svcrdma_sq_retry(rdma);
348 set_bit(XPT_CLOSE, &xprt->xpt_flags);
350 /* If even one was posted, there will be a completion. */
351 if (bad_wr != first_wr)
354 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
355 wake_up(&rdma->sc_send_wait);
359 /* Build and DMA-map an SGL that covers one kvec in an xdr_buf
361 static void svc_rdma_vec_to_sg(struct svc_rdma_write_info *info,
363 struct svc_rdma_rw_ctxt *ctxt)
365 struct scatterlist *sg = ctxt->rw_sg_table.sgl;
367 sg_set_buf(&sg[0], info->wi_base, len);
368 info->wi_base += len;
373 /* Build and DMA-map an SGL that covers part of an xdr_buf's pagelist.
375 static void svc_rdma_pagelist_to_sg(struct svc_rdma_write_info *info,
376 unsigned int remaining,
377 struct svc_rdma_rw_ctxt *ctxt)
379 unsigned int sge_no, sge_bytes, page_off, page_no;
380 struct xdr_buf *xdr = info->wi_xdr;
381 struct scatterlist *sg;
384 page_off = info->wi_next_off + xdr->page_base;
385 page_no = page_off >> PAGE_SHIFT;
386 page_off = offset_in_page(page_off);
387 page = xdr->pages + page_no;
388 info->wi_next_off += remaining;
389 sg = ctxt->rw_sg_table.sgl;
392 sge_bytes = min_t(unsigned int, remaining,
393 PAGE_SIZE - page_off);
394 sg_set_page(sg, *page, sge_bytes, page_off);
396 remaining -= sge_bytes;
403 ctxt->rw_nents = sge_no;
406 /* Construct RDMA Write WRs to send a portion of an xdr_buf containing
410 svc_rdma_build_writes(struct svc_rdma_write_info *info,
411 void (*constructor)(struct svc_rdma_write_info *info,
413 struct svc_rdma_rw_ctxt *ctxt),
414 unsigned int remaining)
416 struct svc_rdma_chunk_ctxt *cc = &info->wi_cc;
417 struct svcxprt_rdma *rdma = cc->cc_rdma;
418 struct svc_rdma_rw_ctxt *ctxt;
422 seg = info->wi_segs + info->wi_seg_no * rpcrdma_segment_maxsz;
424 unsigned int write_len;
425 u32 seg_length, seg_handle;
428 if (info->wi_seg_no >= info->wi_nsegs)
431 seg_handle = be32_to_cpup(seg);
432 seg_length = be32_to_cpup(seg + 1);
433 xdr_decode_hyper(seg + 2, &seg_offset);
434 seg_offset += info->wi_seg_off;
436 write_len = min(remaining, seg_length - info->wi_seg_off);
437 ctxt = svc_rdma_get_rw_ctxt(rdma,
438 (write_len >> PAGE_SHIFT) + 2);
442 constructor(info, write_len, ctxt);
443 ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp,
444 rdma->sc_port_num, ctxt->rw_sg_table.sgl,
445 ctxt->rw_nents, 0, seg_offset,
446 seg_handle, DMA_TO_DEVICE);
450 trace_svcrdma_encode_wseg(seg_handle, write_len, seg_offset);
451 list_add(&ctxt->rw_list, &cc->cc_rwctxts);
452 cc->cc_sqecount += ret;
453 if (write_len == seg_length - info->wi_seg_off) {
456 info->wi_seg_off = 0;
458 info->wi_seg_off += write_len;
460 remaining -= write_len;
466 dprintk("svcrdma: inadequate space in Write chunk (%u)\n",
471 dprintk("svcrdma: no R/W ctxs available\n");
475 svc_rdma_put_rw_ctxt(rdma, ctxt);
476 trace_svcrdma_dma_map_rwctx(rdma, ret);
480 /* Send one of an xdr_buf's kvecs by itself. To send a Reply
481 * chunk, the whole RPC Reply is written back to the client.
482 * This function writes either the head or tail of the xdr_buf
483 * containing the Reply.
485 static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
488 info->wi_base = vec->iov_base;
489 return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
493 /* Send an xdr_buf's page list by itself. A Write chunk is
494 * just the page list. a Reply chunk is the head, page list,
495 * and tail. This function is shared between the two types
498 static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
502 info->wi_next_off = 0;
503 return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
508 * svc_rdma_send_write_chunk - Write all segments in a Write chunk
509 * @rdma: controlling RDMA transport
510 * @wr_ch: Write chunk provided by client
511 * @xdr: xdr_buf containing the data payload
513 * Returns a non-negative number of bytes the chunk consumed, or
514 * %-E2BIG if the payload was larger than the Write chunk,
515 * %-EINVAL if client provided too many segments,
516 * %-ENOMEM if rdma_rw context pool was exhausted,
517 * %-ENOTCONN if posting failed (connection is lost),
518 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
520 int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
523 struct svc_rdma_write_info *info;
529 info = svc_rdma_write_info_alloc(rdma, wr_ch);
533 ret = svc_rdma_send_xdr_pagelist(info, xdr);
537 ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
541 trace_svcrdma_encode_write(xdr->page_len);
542 return xdr->page_len;
545 svc_rdma_write_info_free(info);
550 * svc_rdma_send_reply_chunk - Write all segments in the Reply chunk
551 * @rdma: controlling RDMA transport
552 * @rp_ch: Reply chunk provided by client
553 * @writelist: true if client provided a Write list
554 * @xdr: xdr_buf containing an RPC Reply
556 * Returns a non-negative number of bytes the chunk consumed, or
557 * %-E2BIG if the payload was larger than the Reply chunk,
558 * %-EINVAL if client provided too many segments,
559 * %-ENOMEM if rdma_rw context pool was exhausted,
560 * %-ENOTCONN if posting failed (connection is lost),
561 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
563 int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma, __be32 *rp_ch,
564 bool writelist, struct xdr_buf *xdr)
566 struct svc_rdma_write_info *info;
569 info = svc_rdma_write_info_alloc(rdma, rp_ch);
573 ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]);
576 consumed = xdr->head[0].iov_len;
578 /* Send the page list in the Reply chunk only if the
579 * client did not provide Write chunks.
581 if (!writelist && xdr->page_len) {
582 ret = svc_rdma_send_xdr_pagelist(info, xdr);
585 consumed += xdr->page_len;
588 if (xdr->tail[0].iov_len) {
589 ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]);
592 consumed += xdr->tail[0].iov_len;
595 ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
599 trace_svcrdma_encode_reply(consumed);
603 svc_rdma_write_info_free(info);
607 static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
608 struct svc_rqst *rqstp,
609 u32 rkey, u32 len, u64 offset)
611 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
612 struct svc_rdma_chunk_ctxt *cc = &info->ri_cc;
613 struct svc_rdma_rw_ctxt *ctxt;
614 unsigned int sge_no, seg_len;
615 struct scatterlist *sg;
618 sge_no = PAGE_ALIGN(info->ri_pageoff + len) >> PAGE_SHIFT;
619 ctxt = svc_rdma_get_rw_ctxt(cc->cc_rdma, sge_no);
622 ctxt->rw_nents = sge_no;
624 sg = ctxt->rw_sg_table.sgl;
625 for (sge_no = 0; sge_no < ctxt->rw_nents; sge_no++) {
626 seg_len = min_t(unsigned int, len,
627 PAGE_SIZE - info->ri_pageoff);
629 head->rc_arg.pages[info->ri_pageno] =
630 rqstp->rq_pages[info->ri_pageno];
631 if (!info->ri_pageoff)
632 head->rc_page_count++;
634 sg_set_page(sg, rqstp->rq_pages[info->ri_pageno],
635 seg_len, info->ri_pageoff);
638 info->ri_pageoff += seg_len;
639 if (info->ri_pageoff == PAGE_SIZE) {
641 info->ri_pageoff = 0;
647 &rqstp->rq_pages[info->ri_pageno + 1] > rqstp->rq_page_end)
651 ret = rdma_rw_ctx_init(&ctxt->rw_ctx, cc->cc_rdma->sc_qp,
652 cc->cc_rdma->sc_port_num,
653 ctxt->rw_sg_table.sgl, ctxt->rw_nents,
654 0, offset, rkey, DMA_FROM_DEVICE);
658 list_add(&ctxt->rw_list, &cc->cc_rwctxts);
659 cc->cc_sqecount += ret;
663 dprintk("svcrdma: no R/W ctxs available\n");
667 dprintk("svcrdma: request overruns rq_pages\n");
671 trace_svcrdma_dma_map_rwctx(cc->cc_rdma, ret);
672 svc_rdma_put_rw_ctxt(cc->cc_rdma, ctxt);
676 /* Walk the segments in the Read chunk starting at @p and construct
677 * RDMA Read operations to pull the chunk to the server.
679 static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
680 struct svc_rdma_read_info *info,
686 info->ri_chunklen = 0;
687 while (*p++ != xdr_zero && be32_to_cpup(p++) == info->ri_position) {
688 u32 rs_handle, rs_length;
691 rs_handle = be32_to_cpup(p++);
692 rs_length = be32_to_cpup(p++);
693 p = xdr_decode_hyper(p, &rs_offset);
695 ret = svc_rdma_build_read_segment(info, rqstp,
696 rs_handle, rs_length,
701 trace_svcrdma_encode_rseg(rs_handle, rs_length, rs_offset);
702 info->ri_chunklen += rs_length;
708 /* Construct RDMA Reads to pull over a normal Read chunk. The chunk
709 * data lands in the page list of head->rc_arg.pages.
711 * Currently NFSD does not look at the head->rc_arg.tail[0] iovec.
712 * Therefore, XDR round-up of the Read chunk and trailing
713 * inline content must both be added at the end of the pagelist.
715 static int svc_rdma_build_normal_read_chunk(struct svc_rqst *rqstp,
716 struct svc_rdma_read_info *info,
719 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
722 ret = svc_rdma_build_read_chunk(rqstp, info, p);
726 trace_svcrdma_encode_read(info->ri_chunklen, info->ri_position);
728 head->rc_hdr_count = 0;
730 /* Split the Receive buffer between the head and tail
731 * buffers at Read chunk's position. XDR roundup of the
732 * chunk is not included in either the pagelist or in
735 head->rc_arg.tail[0].iov_base =
736 head->rc_arg.head[0].iov_base + info->ri_position;
737 head->rc_arg.tail[0].iov_len =
738 head->rc_arg.head[0].iov_len - info->ri_position;
739 head->rc_arg.head[0].iov_len = info->ri_position;
741 /* Read chunk may need XDR roundup (see RFC 8166, s. 3.4.5.2).
743 * If the client already rounded up the chunk length, the
744 * length does not change. Otherwise, the length of the page
745 * list is increased to include XDR round-up.
747 * Currently these chunks always start at page offset 0,
748 * thus the rounded-up length never crosses a page boundary.
750 info->ri_chunklen = XDR_QUADLEN(info->ri_chunklen) << 2;
752 head->rc_arg.page_len = info->ri_chunklen;
753 head->rc_arg.len += info->ri_chunklen;
754 head->rc_arg.buflen += info->ri_chunklen;
760 /* Construct RDMA Reads to pull over a Position Zero Read chunk.
761 * The start of the data lands in the first page just after
762 * the Transport header, and the rest lands in the page list of
763 * head->rc_arg.pages.
766 * - A PZRC has an XDR-aligned length (no implicit round-up).
767 * - There can be no trailing inline content (IOW, we assume
768 * a PZRC is never sent in an RDMA_MSG message, though it's
771 static int svc_rdma_build_pz_read_chunk(struct svc_rqst *rqstp,
772 struct svc_rdma_read_info *info,
775 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
778 ret = svc_rdma_build_read_chunk(rqstp, info, p);
782 trace_svcrdma_encode_pzr(info->ri_chunklen);
784 head->rc_arg.len += info->ri_chunklen;
785 head->rc_arg.buflen += info->ri_chunklen;
787 head->rc_hdr_count = 1;
788 head->rc_arg.head[0].iov_base = page_address(head->rc_pages[0]);
789 head->rc_arg.head[0].iov_len = min_t(size_t, PAGE_SIZE,
792 head->rc_arg.page_len = info->ri_chunklen -
793 head->rc_arg.head[0].iov_len;
800 * svc_rdma_recv_read_chunk - Pull a Read chunk from the client
801 * @rdma: controlling RDMA transport
802 * @rqstp: set of pages to use as Read sink buffers
803 * @head: pages under I/O collect here
804 * @p: pointer to start of Read chunk
807 * %0 if all needed RDMA Reads were posted successfully,
808 * %-EINVAL if client provided too many segments,
809 * %-ENOMEM if rdma_rw context pool was exhausted,
810 * %-ENOTCONN if posting failed (connection is lost),
811 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
814 * - All Read segments in @p have the same Position value.
816 int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp,
817 struct svc_rdma_recv_ctxt *head, __be32 *p)
819 struct svc_rdma_read_info *info;
823 /* The request (with page list) is constructed in
824 * head->rc_arg. Pages involved with RDMA Read I/O are
827 head->rc_arg.head[0] = rqstp->rq_arg.head[0];
828 head->rc_arg.tail[0] = rqstp->rq_arg.tail[0];
829 head->rc_arg.pages = head->rc_pages;
830 head->rc_arg.page_base = 0;
831 head->rc_arg.page_len = 0;
832 head->rc_arg.len = rqstp->rq_arg.len;
833 head->rc_arg.buflen = rqstp->rq_arg.buflen;
835 info = svc_rdma_read_info_alloc(rdma);
838 info->ri_readctxt = head;
840 info->ri_pageoff = 0;
842 info->ri_position = be32_to_cpup(p + 1);
843 if (info->ri_position)
844 ret = svc_rdma_build_normal_read_chunk(rqstp, info, p);
846 ret = svc_rdma_build_pz_read_chunk(rqstp, info, p);
848 /* Mark the start of the pages that can be used for the reply */
849 if (info->ri_pageoff > 0)
851 rqstp->rq_respages = &rqstp->rq_pages[info->ri_pageno];
852 rqstp->rq_next_page = rqstp->rq_respages + 1;
857 ret = svc_rdma_post_chunk_ctxt(&info->ri_cc);
860 /* Read sink pages have been moved from rqstp->rq_pages to
861 * head->rc_arg.pages. Force svc_recv to refill those slots
864 for (page = rqstp->rq_pages; page < rqstp->rq_respages; page++)
868 svc_rdma_read_info_free(info);