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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2016-2018 Oracle. All rights reserved.
4 *
5 * Use the core R/W API to move RPC-over-RDMA Read and Write chunks.
6 */
7
8#include <rdma/rw.h>
9
10#include <linux/sunrpc/rpc_rdma.h>
11#include <linux/sunrpc/svc_rdma.h>
12#include <linux/sunrpc/debug.h>
13
14#include "xprt_rdma.h"
15#include <trace/events/rpcrdma.h>
16
17#define RPCDBG_FACILITY RPCDBG_SVCXPRT
18
19static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc);
20static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc);
21
22/* Each R/W context contains state for one chain of RDMA Read or
23 * Write Work Requests.
24 *
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.
28 *
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.
32 *
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.
38 */
39struct svc_rdma_rw_ctxt {
40 struct list_head rw_list;
41 struct rdma_rw_ctx rw_ctx;
42 int rw_nents;
43 struct sg_table rw_sg_table;
44 struct scatterlist rw_first_sgl[0];
45};
46
47static inline struct svc_rdma_rw_ctxt *
48svc_rdma_next_ctxt(struct list_head *list)
49{
50 return list_first_entry_or_null(list, struct svc_rdma_rw_ctxt,
51 rw_list);
52}
53
54static struct svc_rdma_rw_ctxt *
55svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
56{
57 struct svc_rdma_rw_ctxt *ctxt;
58
59 spin_lock(&rdma->sc_rw_ctxt_lock);
60
61 ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts);
62 if (ctxt) {
63 list_del(&ctxt->rw_list);
64 spin_unlock(&rdma->sc_rw_ctxt_lock);
65 } else {
66 spin_unlock(&rdma->sc_rw_ctxt_lock);
67 ctxt = kmalloc(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
68 GFP_KERNEL);
69 if (!ctxt)
70 goto out;
71 INIT_LIST_HEAD(&ctxt->rw_list);
72 }
73
74 ctxt->rw_sg_table.sgl = ctxt->rw_first_sgl;
75 if (sg_alloc_table_chained(&ctxt->rw_sg_table, sges,
76 ctxt->rw_sg_table.sgl,
77 SG_CHUNK_SIZE)) {
78 kfree(ctxt);
79 ctxt = NULL;
80 }
81out:
82 return ctxt;
83}
84
85static void svc_rdma_put_rw_ctxt(struct svcxprt_rdma *rdma,
86 struct svc_rdma_rw_ctxt *ctxt)
87{
88 sg_free_table_chained(&ctxt->rw_sg_table, SG_CHUNK_SIZE);
89
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);
93}
94
95/**
96 * svc_rdma_destroy_rw_ctxts - Free accumulated R/W contexts
97 * @rdma: transport about to be destroyed
98 *
99 */
100void svc_rdma_destroy_rw_ctxts(struct svcxprt_rdma *rdma)
101{
102 struct svc_rdma_rw_ctxt *ctxt;
103
104 while ((ctxt = svc_rdma_next_ctxt(&rdma->sc_rw_ctxts)) != NULL) {
105 list_del(&ctxt->rw_list);
106 kfree(ctxt);
107 }
108}
109
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.
113 *
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.
117 */
118struct svc_rdma_chunk_ctxt {
119 struct ib_cqe cc_cqe;
120 struct svcxprt_rdma *cc_rdma;
121 struct list_head cc_rwctxts;
122 int cc_sqecount;
123};
124
125static void svc_rdma_cc_init(struct svcxprt_rdma *rdma,
126 struct svc_rdma_chunk_ctxt *cc)
127{
128 cc->cc_rdma = rdma;
129 svc_xprt_get(&rdma->sc_xprt);
130
131 INIT_LIST_HEAD(&cc->cc_rwctxts);
132 cc->cc_sqecount = 0;
133}
134
135static void svc_rdma_cc_release(struct svc_rdma_chunk_ctxt *cc,
136 enum dma_data_direction dir)
137{
138 struct svcxprt_rdma *rdma = cc->cc_rdma;
139 struct svc_rdma_rw_ctxt *ctxt;
140
141 while ((ctxt = svc_rdma_next_ctxt(&cc->cc_rwctxts)) != NULL) {
142 list_del(&ctxt->rw_list);
143
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);
148 }
149 svc_xprt_put(&rdma->sc_xprt);
150}
151
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
155 */
156struct 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;
161 __be32 *wi_segs;
162
163 /* SGL constructor arguments */
164 struct xdr_buf *wi_xdr;
165 unsigned char *wi_base;
166 unsigned int wi_next_off;
167
168 struct svc_rdma_chunk_ctxt wi_cc;
169};
170
171static struct svc_rdma_write_info *
172svc_rdma_write_info_alloc(struct svcxprt_rdma *rdma, __be32 *chunk)
173{
174 struct svc_rdma_write_info *info;
175
176 info = kmalloc(sizeof(*info), GFP_KERNEL);
177 if (!info)
178 return info;
179
180 info->wi_seg_off = 0;
181 info->wi_seg_no = 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;
186 return info;
187}
188
189static void svc_rdma_write_info_free(struct svc_rdma_write_info *info)
190{
191 svc_rdma_cc_release(&info->wi_cc, DMA_TO_DEVICE);
192 kfree(info);
193}
194
195/**
196 * svc_rdma_write_done - Write chunk completion
197 * @cq: controlling Completion Queue
198 * @wc: Work Completion
199 *
200 * Pages under I/O are freed by a subsequent Send completion.
201 */
202static void svc_rdma_write_done(struct ib_cq *cq, struct ib_wc *wc)
203{
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);
210
211 trace_svcrdma_wc_write(wc);
212
213 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
214 wake_up(&rdma->sc_send_wait);
215
216 if (unlikely(wc->status != IB_WC_SUCCESS))
217 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
218
219 svc_rdma_write_info_free(info);
220}
221
222/* State for pulling a Read chunk.
223 */
224struct svc_rdma_read_info {
225 struct svc_rdma_recv_ctxt *ri_readctxt;
226 unsigned int ri_position;
227 unsigned int ri_pageno;
228 unsigned int ri_pageoff;
229 unsigned int ri_chunklen;
230
231 struct svc_rdma_chunk_ctxt ri_cc;
232};
233
234static struct svc_rdma_read_info *
235svc_rdma_read_info_alloc(struct svcxprt_rdma *rdma)
236{
237 struct svc_rdma_read_info *info;
238
239 info = kmalloc(sizeof(*info), GFP_KERNEL);
240 if (!info)
241 return info;
242
243 svc_rdma_cc_init(rdma, &info->ri_cc);
244 info->ri_cc.cc_cqe.done = svc_rdma_wc_read_done;
245 return info;
246}
247
248static void svc_rdma_read_info_free(struct svc_rdma_read_info *info)
249{
250 svc_rdma_cc_release(&info->ri_cc, DMA_FROM_DEVICE);
251 kfree(info);
252}
253
254/**
255 * svc_rdma_wc_read_done - Handle completion of an RDMA Read ctx
256 * @cq: controlling Completion Queue
257 * @wc: Work Completion
258 *
259 */
260static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc)
261{
262 struct ib_cqe *cqe = wc->wr_cqe;
263 struct svc_rdma_chunk_ctxt *cc =
264 container_of(cqe, struct svc_rdma_chunk_ctxt, cc_cqe);
265 struct svcxprt_rdma *rdma = cc->cc_rdma;
266 struct svc_rdma_read_info *info =
267 container_of(cc, struct svc_rdma_read_info, ri_cc);
268
269 trace_svcrdma_wc_read(wc);
270
271 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
272 wake_up(&rdma->sc_send_wait);
273
274 if (unlikely(wc->status != IB_WC_SUCCESS)) {
275 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
276 svc_rdma_recv_ctxt_put(rdma, info->ri_readctxt);
277 } else {
278 spin_lock(&rdma->sc_rq_dto_lock);
279 list_add_tail(&info->ri_readctxt->rc_list,
280 &rdma->sc_read_complete_q);
281 /* Note the unlock pairs with the smp_rmb in svc_xprt_ready: */
282 set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags);
283 spin_unlock(&rdma->sc_rq_dto_lock);
284
285 svc_xprt_enqueue(&rdma->sc_xprt);
286 }
287
288 svc_rdma_read_info_free(info);
289}
290
291/* This function sleeps when the transport's Send Queue is congested.
292 *
293 * Assumptions:
294 * - If ib_post_send() succeeds, only one completion is expected,
295 * even if one or more WRs are flushed. This is true when posting
296 * an rdma_rw_ctx or when posting a single signaled WR.
297 */
298static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc)
299{
300 struct svcxprt_rdma *rdma = cc->cc_rdma;
301 struct svc_xprt *xprt = &rdma->sc_xprt;
302 struct ib_send_wr *first_wr;
303 const struct ib_send_wr *bad_wr;
304 struct list_head *tmp;
305 struct ib_cqe *cqe;
306 int ret;
307
308 if (cc->cc_sqecount > rdma->sc_sq_depth)
309 return -EINVAL;
310
311 first_wr = NULL;
312 cqe = &cc->cc_cqe;
313 list_for_each(tmp, &cc->cc_rwctxts) {
314 struct svc_rdma_rw_ctxt *ctxt;
315
316 ctxt = list_entry(tmp, struct svc_rdma_rw_ctxt, rw_list);
317 first_wr = rdma_rw_ctx_wrs(&ctxt->rw_ctx, rdma->sc_qp,
318 rdma->sc_port_num, cqe, first_wr);
319 cqe = NULL;
320 }
321
322 do {
323 if (atomic_sub_return(cc->cc_sqecount,
324 &rdma->sc_sq_avail) > 0) {
325 ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr);
326 trace_svcrdma_post_rw(&cc->cc_cqe,
327 cc->cc_sqecount, ret);
328 if (ret)
329 break;
330 return 0;
331 }
332
333 trace_svcrdma_sq_full(rdma);
334 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
335 wait_event(rdma->sc_send_wait,
336 atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount);
337 trace_svcrdma_sq_retry(rdma);
338 } while (1);
339
340 set_bit(XPT_CLOSE, &xprt->xpt_flags);
341
342 /* If even one was posted, there will be a completion. */
343 if (bad_wr != first_wr)
344 return 0;
345
346 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
347 wake_up(&rdma->sc_send_wait);
348 return -ENOTCONN;
349}
350
351/* Build and DMA-map an SGL that covers one kvec in an xdr_buf
352 */
353static void svc_rdma_vec_to_sg(struct svc_rdma_write_info *info,
354 unsigned int len,
355 struct svc_rdma_rw_ctxt *ctxt)
356{
357 struct scatterlist *sg = ctxt->rw_sg_table.sgl;
358
359 sg_set_buf(&sg[0], info->wi_base, len);
360 info->wi_base += len;
361
362 ctxt->rw_nents = 1;
363}
364
365/* Build and DMA-map an SGL that covers part of an xdr_buf's pagelist.
366 */
367static void svc_rdma_pagelist_to_sg(struct svc_rdma_write_info *info,
368 unsigned int remaining,
369 struct svc_rdma_rw_ctxt *ctxt)
370{
371 unsigned int sge_no, sge_bytes, page_off, page_no;
372 struct xdr_buf *xdr = info->wi_xdr;
373 struct scatterlist *sg;
374 struct page **page;
375
376 page_off = info->wi_next_off + xdr->page_base;
377 page_no = page_off >> PAGE_SHIFT;
378 page_off = offset_in_page(page_off);
379 page = xdr->pages + page_no;
380 info->wi_next_off += remaining;
381 sg = ctxt->rw_sg_table.sgl;
382 sge_no = 0;
383 do {
384 sge_bytes = min_t(unsigned int, remaining,
385 PAGE_SIZE - page_off);
386 sg_set_page(sg, *page, sge_bytes, page_off);
387
388 remaining -= sge_bytes;
389 sg = sg_next(sg);
390 page_off = 0;
391 sge_no++;
392 page++;
393 } while (remaining);
394
395 ctxt->rw_nents = sge_no;
396}
397
398/* Construct RDMA Write WRs to send a portion of an xdr_buf containing
399 * an RPC Reply.
400 */
401static int
402svc_rdma_build_writes(struct svc_rdma_write_info *info,
403 void (*constructor)(struct svc_rdma_write_info *info,
404 unsigned int len,
405 struct svc_rdma_rw_ctxt *ctxt),
406 unsigned int remaining)
407{
408 struct svc_rdma_chunk_ctxt *cc = &info->wi_cc;
409 struct svcxprt_rdma *rdma = cc->cc_rdma;
410 struct svc_rdma_rw_ctxt *ctxt;
411 __be32 *seg;
412 int ret;
413
414 seg = info->wi_segs + info->wi_seg_no * rpcrdma_segment_maxsz;
415 do {
416 unsigned int write_len;
417 u32 seg_length, seg_handle;
418 u64 seg_offset;
419
420 if (info->wi_seg_no >= info->wi_nsegs)
421 goto out_overflow;
422
423 seg_handle = be32_to_cpup(seg);
424 seg_length = be32_to_cpup(seg + 1);
425 xdr_decode_hyper(seg + 2, &seg_offset);
426 seg_offset += info->wi_seg_off;
427
428 write_len = min(remaining, seg_length - info->wi_seg_off);
429 ctxt = svc_rdma_get_rw_ctxt(rdma,
430 (write_len >> PAGE_SHIFT) + 2);
431 if (!ctxt)
432 goto out_noctx;
433
434 constructor(info, write_len, ctxt);
435 ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp,
436 rdma->sc_port_num, ctxt->rw_sg_table.sgl,
437 ctxt->rw_nents, 0, seg_offset,
438 seg_handle, DMA_TO_DEVICE);
439 if (ret < 0)
440 goto out_initerr;
441
442 trace_svcrdma_encode_wseg(seg_handle, write_len, seg_offset);
443 list_add(&ctxt->rw_list, &cc->cc_rwctxts);
444 cc->cc_sqecount += ret;
445 if (write_len == seg_length - info->wi_seg_off) {
446 seg += 4;
447 info->wi_seg_no++;
448 info->wi_seg_off = 0;
449 } else {
450 info->wi_seg_off += write_len;
451 }
452 remaining -= write_len;
453 } while (remaining);
454
455 return 0;
456
457out_overflow:
458 dprintk("svcrdma: inadequate space in Write chunk (%u)\n",
459 info->wi_nsegs);
460 return -E2BIG;
461
462out_noctx:
463 dprintk("svcrdma: no R/W ctxs available\n");
464 return -ENOMEM;
465
466out_initerr:
467 svc_rdma_put_rw_ctxt(rdma, ctxt);
468 trace_svcrdma_dma_map_rwctx(rdma, ret);
469 return -EIO;
470}
471
472/* Send one of an xdr_buf's kvecs by itself. To send a Reply
473 * chunk, the whole RPC Reply is written back to the client.
474 * This function writes either the head or tail of the xdr_buf
475 * containing the Reply.
476 */
477static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
478 struct kvec *vec)
479{
480 info->wi_base = vec->iov_base;
481 return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
482 vec->iov_len);
483}
484
485/* Send an xdr_buf's page list by itself. A Write chunk is
486 * just the page list. a Reply chunk is the head, page list,
487 * and tail. This function is shared between the two types
488 * of chunk.
489 */
490static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
491 struct xdr_buf *xdr)
492{
493 info->wi_xdr = xdr;
494 info->wi_next_off = 0;
495 return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
496 xdr->page_len);
497}
498
499/**
500 * svc_rdma_send_write_chunk - Write all segments in a Write chunk
501 * @rdma: controlling RDMA transport
502 * @wr_ch: Write chunk provided by client
503 * @xdr: xdr_buf containing the data payload
504 *
505 * Returns a non-negative number of bytes the chunk consumed, or
506 * %-E2BIG if the payload was larger than the Write chunk,
507 * %-EINVAL if client provided too many segments,
508 * %-ENOMEM if rdma_rw context pool was exhausted,
509 * %-ENOTCONN if posting failed (connection is lost),
510 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
511 */
512int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
513 struct xdr_buf *xdr)
514{
515 struct svc_rdma_write_info *info;
516 int ret;
517
518 if (!xdr->page_len)
519 return 0;
520
521 info = svc_rdma_write_info_alloc(rdma, wr_ch);
522 if (!info)
523 return -ENOMEM;
524
525 ret = svc_rdma_send_xdr_pagelist(info, xdr);
526 if (ret < 0)
527 goto out_err;
528
529 ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
530 if (ret < 0)
531 goto out_err;
532
533 trace_svcrdma_encode_write(xdr->page_len);
534 return xdr->page_len;
535
536out_err:
537 svc_rdma_write_info_free(info);
538 return ret;
539}
540
541/**
542 * svc_rdma_send_reply_chunk - Write all segments in the Reply chunk
543 * @rdma: controlling RDMA transport
544 * @rp_ch: Reply chunk provided by client
545 * @writelist: true if client provided a Write list
546 * @xdr: xdr_buf containing an RPC Reply
547 *
548 * Returns a non-negative number of bytes the chunk consumed, or
549 * %-E2BIG if the payload was larger than the Reply chunk,
550 * %-EINVAL if client provided too many segments,
551 * %-ENOMEM if rdma_rw context pool was exhausted,
552 * %-ENOTCONN if posting failed (connection is lost),
553 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
554 */
555int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma, __be32 *rp_ch,
556 bool writelist, struct xdr_buf *xdr)
557{
558 struct svc_rdma_write_info *info;
559 int consumed, ret;
560
561 info = svc_rdma_write_info_alloc(rdma, rp_ch);
562 if (!info)
563 return -ENOMEM;
564
565 ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]);
566 if (ret < 0)
567 goto out_err;
568 consumed = xdr->head[0].iov_len;
569
570 /* Send the page list in the Reply chunk only if the
571 * client did not provide Write chunks.
572 */
573 if (!writelist && xdr->page_len) {
574 ret = svc_rdma_send_xdr_pagelist(info, xdr);
575 if (ret < 0)
576 goto out_err;
577 consumed += xdr->page_len;
578 }
579
580 if (xdr->tail[0].iov_len) {
581 ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]);
582 if (ret < 0)
583 goto out_err;
584 consumed += xdr->tail[0].iov_len;
585 }
586
587 ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
588 if (ret < 0)
589 goto out_err;
590
591 trace_svcrdma_encode_reply(consumed);
592 return consumed;
593
594out_err:
595 svc_rdma_write_info_free(info);
596 return ret;
597}
598
599static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
600 struct svc_rqst *rqstp,
601 u32 rkey, u32 len, u64 offset)
602{
603 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
604 struct svc_rdma_chunk_ctxt *cc = &info->ri_cc;
605 struct svc_rdma_rw_ctxt *ctxt;
606 unsigned int sge_no, seg_len;
607 struct scatterlist *sg;
608 int ret;
609
610 sge_no = PAGE_ALIGN(info->ri_pageoff + len) >> PAGE_SHIFT;
611 ctxt = svc_rdma_get_rw_ctxt(cc->cc_rdma, sge_no);
612 if (!ctxt)
613 goto out_noctx;
614 ctxt->rw_nents = sge_no;
615
616 sg = ctxt->rw_sg_table.sgl;
617 for (sge_no = 0; sge_no < ctxt->rw_nents; sge_no++) {
618 seg_len = min_t(unsigned int, len,
619 PAGE_SIZE - info->ri_pageoff);
620
621 head->rc_arg.pages[info->ri_pageno] =
622 rqstp->rq_pages[info->ri_pageno];
623 if (!info->ri_pageoff)
624 head->rc_page_count++;
625
626 sg_set_page(sg, rqstp->rq_pages[info->ri_pageno],
627 seg_len, info->ri_pageoff);
628 sg = sg_next(sg);
629
630 info->ri_pageoff += seg_len;
631 if (info->ri_pageoff == PAGE_SIZE) {
632 info->ri_pageno++;
633 info->ri_pageoff = 0;
634 }
635 len -= seg_len;
636
637 /* Safety check */
638 if (len &&
639 &rqstp->rq_pages[info->ri_pageno + 1] > rqstp->rq_page_end)
640 goto out_overrun;
641 }
642
643 ret = rdma_rw_ctx_init(&ctxt->rw_ctx, cc->cc_rdma->sc_qp,
644 cc->cc_rdma->sc_port_num,
645 ctxt->rw_sg_table.sgl, ctxt->rw_nents,
646 0, offset, rkey, DMA_FROM_DEVICE);
647 if (ret < 0)
648 goto out_initerr;
649
650 list_add(&ctxt->rw_list, &cc->cc_rwctxts);
651 cc->cc_sqecount += ret;
652 return 0;
653
654out_noctx:
655 dprintk("svcrdma: no R/W ctxs available\n");
656 return -ENOMEM;
657
658out_overrun:
659 dprintk("svcrdma: request overruns rq_pages\n");
660 return -EINVAL;
661
662out_initerr:
663 trace_svcrdma_dma_map_rwctx(cc->cc_rdma, ret);
664 svc_rdma_put_rw_ctxt(cc->cc_rdma, ctxt);
665 return -EIO;
666}
667
668/* Walk the segments in the Read chunk starting at @p and construct
669 * RDMA Read operations to pull the chunk to the server.
670 */
671static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
672 struct svc_rdma_read_info *info,
673 __be32 *p)
674{
675 unsigned int i;
676 int ret;
677
678 ret = -EINVAL;
679 info->ri_chunklen = 0;
680 while (*p++ != xdr_zero && be32_to_cpup(p++) == info->ri_position) {
681 u32 rs_handle, rs_length;
682 u64 rs_offset;
683
684 rs_handle = be32_to_cpup(p++);
685 rs_length = be32_to_cpup(p++);
686 p = xdr_decode_hyper(p, &rs_offset);
687
688 ret = svc_rdma_build_read_segment(info, rqstp,
689 rs_handle, rs_length,
690 rs_offset);
691 if (ret < 0)
692 break;
693
694 trace_svcrdma_encode_rseg(rs_handle, rs_length, rs_offset);
695 info->ri_chunklen += rs_length;
696 }
697
698 /* Pages under I/O have been copied to head->rc_pages.
699 * Prevent their premature release by svc_xprt_release() .
700 */
701 for (i = 0; i < info->ri_readctxt->rc_page_count; i++)
702 rqstp->rq_pages[i] = NULL;
703
704 return ret;
705}
706
707/* Construct RDMA Reads to pull over a normal Read chunk. The chunk
708 * data lands in the page list of head->rc_arg.pages.
709 *
710 * Currently NFSD does not look at the head->rc_arg.tail[0] iovec.
711 * Therefore, XDR round-up of the Read chunk and trailing
712 * inline content must both be added at the end of the pagelist.
713 */
714static int svc_rdma_build_normal_read_chunk(struct svc_rqst *rqstp,
715 struct svc_rdma_read_info *info,
716 __be32 *p)
717{
718 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
719 int ret;
720
721 ret = svc_rdma_build_read_chunk(rqstp, info, p);
722 if (ret < 0)
723 goto out;
724
725 trace_svcrdma_encode_read(info->ri_chunklen, info->ri_position);
726
727 head->rc_hdr_count = 0;
728
729 /* Split the Receive buffer between the head and tail
730 * buffers at Read chunk's position. XDR roundup of the
731 * chunk is not included in either the pagelist or in
732 * the tail.
733 */
734 head->rc_arg.tail[0].iov_base =
735 head->rc_arg.head[0].iov_base + info->ri_position;
736 head->rc_arg.tail[0].iov_len =
737 head->rc_arg.head[0].iov_len - info->ri_position;
738 head->rc_arg.head[0].iov_len = info->ri_position;
739
740 /* Read chunk may need XDR roundup (see RFC 8166, s. 3.4.5.2).
741 *
742 * If the client already rounded up the chunk length, the
743 * length does not change. Otherwise, the length of the page
744 * list is increased to include XDR round-up.
745 *
746 * Currently these chunks always start at page offset 0,
747 * thus the rounded-up length never crosses a page boundary.
748 */
749 info->ri_chunklen = XDR_QUADLEN(info->ri_chunklen) << 2;
750
751 head->rc_arg.page_len = info->ri_chunklen;
752 head->rc_arg.len += info->ri_chunklen;
753 head->rc_arg.buflen += info->ri_chunklen;
754
755out:
756 return ret;
757}
758
759/* Construct RDMA Reads to pull over a Position Zero Read chunk.
760 * The start of the data lands in the first page just after
761 * the Transport header, and the rest lands in the page list of
762 * head->rc_arg.pages.
763 *
764 * Assumptions:
765 * - A PZRC has an XDR-aligned length (no implicit round-up).
766 * - There can be no trailing inline content (IOW, we assume
767 * a PZRC is never sent in an RDMA_MSG message, though it's
768 * allowed by spec).
769 */
770static int svc_rdma_build_pz_read_chunk(struct svc_rqst *rqstp,
771 struct svc_rdma_read_info *info,
772 __be32 *p)
773{
774 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
775 int ret;
776
777 ret = svc_rdma_build_read_chunk(rqstp, info, p);
778 if (ret < 0)
779 goto out;
780
781 trace_svcrdma_encode_pzr(info->ri_chunklen);
782
783 head->rc_arg.len += info->ri_chunklen;
784 head->rc_arg.buflen += info->ri_chunklen;
785
786 head->rc_hdr_count = 1;
787 head->rc_arg.head[0].iov_base = page_address(head->rc_pages[0]);
788 head->rc_arg.head[0].iov_len = min_t(size_t, PAGE_SIZE,
789 info->ri_chunklen);
790
791 head->rc_arg.page_len = info->ri_chunklen -
792 head->rc_arg.head[0].iov_len;
793
794out:
795 return ret;
796}
797
798/**
799 * svc_rdma_recv_read_chunk - Pull a Read chunk from the client
800 * @rdma: controlling RDMA transport
801 * @rqstp: set of pages to use as Read sink buffers
802 * @head: pages under I/O collect here
803 * @p: pointer to start of Read chunk
804 *
805 * Returns:
806 * %0 if all needed RDMA Reads were posted successfully,
807 * %-EINVAL if client provided too many segments,
808 * %-ENOMEM if rdma_rw context pool was exhausted,
809 * %-ENOTCONN if posting failed (connection is lost),
810 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
811 *
812 * Assumptions:
813 * - All Read segments in @p have the same Position value.
814 */
815int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp,
816 struct svc_rdma_recv_ctxt *head, __be32 *p)
817{
818 struct svc_rdma_read_info *info;
819 int ret;
820
821 /* The request (with page list) is constructed in
822 * head->rc_arg. Pages involved with RDMA Read I/O are
823 * transferred there.
824 */
825 head->rc_arg.head[0] = rqstp->rq_arg.head[0];
826 head->rc_arg.tail[0] = rqstp->rq_arg.tail[0];
827 head->rc_arg.pages = head->rc_pages;
828 head->rc_arg.page_base = 0;
829 head->rc_arg.page_len = 0;
830 head->rc_arg.len = rqstp->rq_arg.len;
831 head->rc_arg.buflen = rqstp->rq_arg.buflen;
832
833 info = svc_rdma_read_info_alloc(rdma);
834 if (!info)
835 return -ENOMEM;
836 info->ri_readctxt = head;
837 info->ri_pageno = 0;
838 info->ri_pageoff = 0;
839
840 info->ri_position = be32_to_cpup(p + 1);
841 if (info->ri_position)
842 ret = svc_rdma_build_normal_read_chunk(rqstp, info, p);
843 else
844 ret = svc_rdma_build_pz_read_chunk(rqstp, info, p);
845 if (ret < 0)
846 goto out_err;
847
848 ret = svc_rdma_post_chunk_ctxt(&info->ri_cc);
849 if (ret < 0)
850 goto out_err;
851 return 0;
852
853out_err:
854 svc_rdma_read_info_free(info);
855 return ret;
856}