net/sunrpc/xprtrdma/svc_rdma_rw.c

   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
  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);
  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  */
  39 struct 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
  47 static inline struct svc_rdma_rw_ctxt *
  48 svc_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
  54 static struct svc_rdma_rw_ctxt *
  55 svc_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(sizeof(*ctxt) +
  68                                SG_CHUNK_SIZE * sizeof(struct scatterlist),
  69                                GFP_KERNEL);
  70                 if (!ctxt)
  71                         goto out;
  72                 INIT_LIST_HEAD(&ctxt->rw_list);
  73         }
  74
  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)) {
  78                 kfree(ctxt);
  79                 ctxt = NULL;
  80         }
  81 out:
  82         return ctxt;
  83 }
  84
  85 static 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, true);
  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  */
 100 void 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  */
 118 struct 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
 125 static 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
 135 static 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  */
 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;
 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
 171 static struct svc_rdma_write_info *
 172 svc_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
 189 static 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  */
 202 static 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                 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);
 222         }
 223
 224         svc_rdma_write_info_free(info);
 225 }
 226
 227 /* State for pulling a Read chunk.
 228  */
 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;
 235
 236         struct svc_rdma_chunk_ctxt      ri_cc;
 237 };
 238
 239 static struct svc_rdma_read_info *
 240 svc_rdma_read_info_alloc(struct svcxprt_rdma *rdma)
 241 {
 242         struct svc_rdma_read_info *info;
 243
 244         info = kmalloc(sizeof(*info), GFP_KERNEL);
 245         if (!info)
 246                 return info;
 247
 248         svc_rdma_cc_init(rdma, &info->ri_cc);
 249         info->ri_cc.cc_cqe.done = svc_rdma_wc_read_done;
 250         return info;
 251 }
 252
 253 static void svc_rdma_read_info_free(struct svc_rdma_read_info *info)
 254 {
 255         svc_rdma_cc_release(&info->ri_cc, DMA_FROM_DEVICE);
 256         kfree(info);
 257 }
 258
 259 /**
 260  * svc_rdma_wc_read_done - Handle completion of an RDMA Read ctx
 261  * @cq: controlling Completion Queue
 262  * @wc: Work Completion
 263  *
 264  */
 265 static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc)
 266 {
 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);
 273
 274         trace_svcrdma_wc_read(wc);
 275
 276         atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
 277         wake_up(&rdma->sc_send_wait);
 278
 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);
 286         } else {
 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);
 291
 292                 set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags);
 293                 svc_xprt_enqueue(&rdma->sc_xprt);
 294         }
 295
 296         svc_rdma_read_info_free(info);
 297 }
 298
 299 /* This function sleeps when the transport's Send Queue is congested.
 300  *
 301  * Assumptions:
 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.
 305  */
 306 static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc)
 307 {
 308         struct svcxprt_rdma *rdma = cc->cc_rdma;
 309         struct svc_xprt *xprt = &rdma->sc_xprt;
 310         struct ib_send_wr *first_wr, *bad_wr;
 311         struct list_head *tmp;
 312         struct ib_cqe *cqe;
 313         int ret;
 314
 315         if (cc->cc_sqecount > rdma->sc_sq_depth)
 316                 return -EINVAL;
 317
 318         first_wr = NULL;
 319         cqe = &cc->cc_cqe;
 320         list_for_each(tmp, &cc->cc_rwctxts) {
 321                 struct svc_rdma_rw_ctxt *ctxt;
 322
 323                 ctxt = list_entry(tmp, struct svc_rdma_rw_ctxt, rw_list);
 324                 first_wr = rdma_rw_ctx_wrs(&ctxt->rw_ctx, rdma->sc_qp,
 325                                            rdma->sc_port_num, cqe, first_wr);
 326                 cqe = NULL;
 327         }
 328
 329         do {
 330                 if (atomic_sub_return(cc->cc_sqecount,
 331                                       &rdma->sc_sq_avail) > 0) {
 332                         ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr);
 333                         trace_svcrdma_post_rw(&cc->cc_cqe,
 334                                               cc->cc_sqecount, ret);
 335                         if (ret)
 336                                 break;
 337                         return 0;
 338                 }
 339
 340                 trace_svcrdma_sq_full(rdma);
 341                 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
 342                 wait_event(rdma->sc_send_wait,
 343                            atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount);
 344                 trace_svcrdma_sq_retry(rdma);
 345         } while (1);
 346
 347         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 348
 349         /* If even one was posted, there will be a completion. */
 350         if (bad_wr != first_wr)
 351                 return 0;
 352
 353         atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
 354         wake_up(&rdma->sc_send_wait);
 355         return -ENOTCONN;
 356 }
 357
 358 /* Build and DMA-map an SGL that covers one kvec in an xdr_buf
 359  */
 360 static void svc_rdma_vec_to_sg(struct svc_rdma_write_info *info,
 361                                unsigned int len,
 362                                struct svc_rdma_rw_ctxt *ctxt)
 363 {
 364         struct scatterlist *sg = ctxt->rw_sg_table.sgl;
 365
 366         sg_set_buf(&sg[0], info->wi_base, len);
 367         info->wi_base += len;
 368
 369         ctxt->rw_nents = 1;
 370 }
 371
 372 /* Build and DMA-map an SGL that covers part of an xdr_buf's pagelist.
 373  */
 374 static void svc_rdma_pagelist_to_sg(struct svc_rdma_write_info *info,
 375                                     unsigned int remaining,
 376                                     struct svc_rdma_rw_ctxt *ctxt)
 377 {
 378         unsigned int sge_no, sge_bytes, page_off, page_no;
 379         struct xdr_buf *xdr = info->wi_xdr;
 380         struct scatterlist *sg;
 381         struct page **page;
 382
 383         page_off = info->wi_next_off + xdr->page_base;
 384         page_no = page_off >> PAGE_SHIFT;
 385         page_off = offset_in_page(page_off);
 386         page = xdr->pages + page_no;
 387         info->wi_next_off += remaining;
 388         sg = ctxt->rw_sg_table.sgl;
 389         sge_no = 0;
 390         do {
 391                 sge_bytes = min_t(unsigned int, remaining,
 392                                   PAGE_SIZE - page_off);
 393                 sg_set_page(sg, *page, sge_bytes, page_off);
 394
 395                 remaining -= sge_bytes;
 396                 sg = sg_next(sg);
 397                 page_off = 0;
 398                 sge_no++;
 399                 page++;
 400         } while (remaining);
 401
 402         ctxt->rw_nents = sge_no;
 403 }
 404
 405 /* Construct RDMA Write WRs to send a portion of an xdr_buf containing
 406  * an RPC Reply.
 407  */
 408 static int
 409 svc_rdma_build_writes(struct svc_rdma_write_info *info,
 410                       void (*constructor)(struct svc_rdma_write_info *info,
 411                                           unsigned int len,
 412                                           struct svc_rdma_rw_ctxt *ctxt),
 413                       unsigned int remaining)
 414 {
 415         struct svc_rdma_chunk_ctxt *cc = &info->wi_cc;
 416         struct svcxprt_rdma *rdma = cc->cc_rdma;
 417         struct svc_rdma_rw_ctxt *ctxt;
 418         __be32 *seg;
 419         int ret;
 420
 421         seg = info->wi_segs + info->wi_seg_no * rpcrdma_segment_maxsz;
 422         do {
 423                 unsigned int write_len;
 424                 u32 seg_length, seg_handle;
 425                 u64 seg_offset;
 426
 427                 if (info->wi_seg_no >= info->wi_nsegs)
 428                         goto out_overflow;
 429
 430                 seg_handle = be32_to_cpup(seg);
 431                 seg_length = be32_to_cpup(seg + 1);
 432                 xdr_decode_hyper(seg + 2, &seg_offset);
 433                 seg_offset += info->wi_seg_off;
 434
 435                 write_len = min(remaining, seg_length - info->wi_seg_off);
 436                 ctxt = svc_rdma_get_rw_ctxt(rdma,
 437                                             (write_len >> PAGE_SHIFT) + 2);
 438                 if (!ctxt)
 439                         goto out_noctx;
 440
 441                 constructor(info, write_len, ctxt);
 442                 ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp,
 443                                        rdma->sc_port_num, ctxt->rw_sg_table.sgl,
 444                                        ctxt->rw_nents, 0, seg_offset,
 445                                        seg_handle, DMA_TO_DEVICE);
 446                 if (ret < 0)
 447                         goto out_initerr;
 448
 449                 trace_svcrdma_encode_wseg(seg_handle, write_len, seg_offset);
 450                 list_add(&ctxt->rw_list, &cc->cc_rwctxts);
 451                 cc->cc_sqecount += ret;
 452                 if (write_len == seg_length - info->wi_seg_off) {
 453                         seg += 4;
 454                         info->wi_seg_no++;
 455                         info->wi_seg_off = 0;
 456                 } else {
 457                         info->wi_seg_off += write_len;
 458                 }
 459                 remaining -= write_len;
 460         } while (remaining);
 461
 462         return 0;
 463
 464 out_overflow:
 465         dprintk("svcrdma: inadequate space in Write chunk (%u)\n",
 466                 info->wi_nsegs);
 467         return -E2BIG;
 468
 469 out_noctx:
 470         dprintk("svcrdma: no R/W ctxs available\n");
 471         return -ENOMEM;
 472
 473 out_initerr:
 474         svc_rdma_put_rw_ctxt(rdma, ctxt);
 475         trace_svcrdma_dma_map_rwctx(rdma, ret);
 476         return -EIO;
 477 }
 478
 479 /* Send one of an xdr_buf's kvecs by itself. To send a Reply
 480  * chunk, the whole RPC Reply is written back to the client.
 481  * This function writes either the head or tail of the xdr_buf
 482  * containing the Reply.
 483  */
 484 static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
 485                                   struct kvec *vec)
 486 {
 487         info->wi_base = vec->iov_base;
 488         return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
 489                                      vec->iov_len);
 490 }
 491
 492 /* Send an xdr_buf's page list by itself. A Write chunk is
 493  * just the page list. a Reply chunk is the head, page list,
 494  * and tail. This function is shared between the two types
 495  * of chunk.
 496  */
 497 static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
 498                                       struct xdr_buf *xdr)
 499 {
 500         info->wi_xdr = xdr;
 501         info->wi_next_off = 0;
 502         return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
 503                                      xdr->page_len);
 504 }
 505
 506 /**
 507  * svc_rdma_send_write_chunk - Write all segments in a Write chunk
 508  * @rdma: controlling RDMA transport
 509  * @wr_ch: Write chunk provided by client
 510  * @xdr: xdr_buf containing the data payload
 511  *
 512  * Returns a non-negative number of bytes the chunk consumed, or
 513  *      %-E2BIG if the payload was larger than the Write chunk,
 514  *      %-EINVAL if client provided too many segments,
 515  *      %-ENOMEM if rdma_rw context pool was exhausted,
 516  *      %-ENOTCONN if posting failed (connection is lost),
 517  *      %-EIO if rdma_rw initialization failed (DMA mapping, etc).
 518  */
 519 int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
 520                               struct xdr_buf *xdr)
 521 {
 522         struct svc_rdma_write_info *info;
 523         int ret;
 524
 525         if (!xdr->page_len)
 526                 return 0;
 527
 528         info = svc_rdma_write_info_alloc(rdma, wr_ch);
 529         if (!info)
 530                 return -ENOMEM;
 531
 532         ret = svc_rdma_send_xdr_pagelist(info, xdr);
 533         if (ret < 0)
 534                 goto out_err;
 535
 536         ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
 537         if (ret < 0)
 538                 goto out_err;
 539
 540         trace_svcrdma_encode_write(xdr->page_len);
 541         return xdr->page_len;
 542
 543 out_err:
 544         svc_rdma_write_info_free(info);
 545         return ret;
 546 }
 547
 548 /**
 549  * svc_rdma_send_reply_chunk - Write all segments in the Reply chunk
 550  * @rdma: controlling RDMA transport
 551  * @rp_ch: Reply chunk provided by client
 552  * @writelist: true if client provided a Write list
 553  * @xdr: xdr_buf containing an RPC Reply
 554  *
 555  * Returns a non-negative number of bytes the chunk consumed, or
 556  *      %-E2BIG if the payload was larger than the Reply chunk,
 557  *      %-EINVAL if client provided too many segments,
 558  *      %-ENOMEM if rdma_rw context pool was exhausted,
 559  *      %-ENOTCONN if posting failed (connection is lost),
 560  *      %-EIO if rdma_rw initialization failed (DMA mapping, etc).
 561  */
 562 int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma, __be32 *rp_ch,
 563                               bool writelist, struct xdr_buf *xdr)
 564 {
 565         struct svc_rdma_write_info *info;
 566         int consumed, ret;
 567
 568         info = svc_rdma_write_info_alloc(rdma, rp_ch);
 569         if (!info)
 570                 return -ENOMEM;
 571
 572         ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]);
 573         if (ret < 0)
 574                 goto out_err;
 575         consumed = xdr->head[0].iov_len;
 576
 577         /* Send the page list in the Reply chunk only if the
 578          * client did not provide Write chunks.
 579          */
 580         if (!writelist && xdr->page_len) {
 581                 ret = svc_rdma_send_xdr_pagelist(info, xdr);
 582                 if (ret < 0)
 583                         goto out_err;
 584                 consumed += xdr->page_len;
 585         }
 586
 587         if (xdr->tail[0].iov_len) {
 588                 ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]);
 589                 if (ret < 0)
 590                         goto out_err;
 591                 consumed += xdr->tail[0].iov_len;
 592         }
 593
 594         ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
 595         if (ret < 0)
 596                 goto out_err;
 597
 598         trace_svcrdma_encode_reply(consumed);
 599         return consumed;
 600
 601 out_err:
 602         svc_rdma_write_info_free(info);
 603         return ret;
 604 }
 605
 606 static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
 607                                        struct svc_rqst *rqstp,
 608                                        u32 rkey, u32 len, u64 offset)
 609 {
 610         struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
 611         struct svc_rdma_chunk_ctxt *cc = &info->ri_cc;
 612         struct svc_rdma_rw_ctxt *ctxt;
 613         unsigned int sge_no, seg_len;
 614         struct scatterlist *sg;
 615         int ret;
 616
 617         sge_no = PAGE_ALIGN(info->ri_pageoff + len) >> PAGE_SHIFT;
 618         ctxt = svc_rdma_get_rw_ctxt(cc->cc_rdma, sge_no);
 619         if (!ctxt)
 620                 goto out_noctx;
 621         ctxt->rw_nents = sge_no;
 622
 623         sg = ctxt->rw_sg_table.sgl;
 624         for (sge_no = 0; sge_no < ctxt->rw_nents; sge_no++) {
 625                 seg_len = min_t(unsigned int, len,
 626                                 PAGE_SIZE - info->ri_pageoff);
 627
 628                 head->rc_arg.pages[info->ri_pageno] =
 629                         rqstp->rq_pages[info->ri_pageno];
 630                 if (!info->ri_pageoff)
 631                         head->rc_page_count++;
 632
 633                 sg_set_page(sg, rqstp->rq_pages[info->ri_pageno],
 634                             seg_len, info->ri_pageoff);
 635                 sg = sg_next(sg);
 636
 637                 info->ri_pageoff += seg_len;
 638                 if (info->ri_pageoff == PAGE_SIZE) {
 639                         info->ri_pageno++;
 640                         info->ri_pageoff = 0;
 641                 }
 642                 len -= seg_len;
 643
 644                 /* Safety check */
 645                 if (len &&
 646                     &rqstp->rq_pages[info->ri_pageno + 1] > rqstp->rq_page_end)
 647                         goto out_overrun;
 648         }
 649
 650         ret = rdma_rw_ctx_init(&ctxt->rw_ctx, cc->cc_rdma->sc_qp,
 651                                cc->cc_rdma->sc_port_num,
 652                                ctxt->rw_sg_table.sgl, ctxt->rw_nents,
 653                                0, offset, rkey, DMA_FROM_DEVICE);
 654         if (ret < 0)
 655                 goto out_initerr;
 656
 657         list_add(&ctxt->rw_list, &cc->cc_rwctxts);
 658         cc->cc_sqecount += ret;
 659         return 0;
 660
 661 out_noctx:
 662         dprintk("svcrdma: no R/W ctxs available\n");
 663         return -ENOMEM;
 664
 665 out_overrun:
 666         dprintk("svcrdma: request overruns rq_pages\n");
 667         return -EINVAL;
 668
 669 out_initerr:
 670         trace_svcrdma_dma_map_rwctx(cc->cc_rdma, ret);
 671         svc_rdma_put_rw_ctxt(cc->cc_rdma, ctxt);
 672         return -EIO;
 673 }
 674
 675 /* Walk the segments in the Read chunk starting at @p and construct
 676  * RDMA Read operations to pull the chunk to the server.
 677  */
 678 static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
 679                                      struct svc_rdma_read_info *info,
 680                                      __be32 *p)
 681 {
 682         unsigned int i;
 683         int ret;
 684
 685         ret = -EINVAL;
 686         info->ri_chunklen = 0;
 687         while (*p++ != xdr_zero && be32_to_cpup(p++) == info->ri_position) {
 688                 u32 rs_handle, rs_length;
 689                 u64 rs_offset;
 690
 691                 rs_handle = be32_to_cpup(p++);
 692                 rs_length = be32_to_cpup(p++);
 693                 p = xdr_decode_hyper(p, &rs_offset);
 694
 695                 ret = svc_rdma_build_read_segment(info, rqstp,
 696                                                   rs_handle, rs_length,
 697                                                   rs_offset);
 698                 if (ret < 0)
 699                         break;
 700
 701                 trace_svcrdma_encode_rseg(rs_handle, rs_length, rs_offset);
 702                 info->ri_chunklen += rs_length;
 703         }
 704
 705         /* Pages under I/O have been copied to head->rc_pages.
 706          * Prevent their premature release by svc_xprt_release() .
 707          */
 708         for (i = 0; i < info->ri_readctxt->rc_page_count; i++)
 709                 rqstp->rq_pages[i] = NULL;
 710
 711         return ret;
 712 }
 713
 714 /* Construct RDMA Reads to pull over a normal Read chunk. The chunk
 715  * data lands in the page list of head->rc_arg.pages.
 716  *
 717  * Currently NFSD does not look at the head->rc_arg.tail[0] iovec.
 718  * Therefore, XDR round-up of the Read chunk and trailing
 719  * inline content must both be added at the end of the pagelist.
 720  */
 721 static int svc_rdma_build_normal_read_chunk(struct svc_rqst *rqstp,
 722                                             struct svc_rdma_read_info *info,
 723                                             __be32 *p)
 724 {
 725         struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
 726         int ret;
 727
 728         ret = svc_rdma_build_read_chunk(rqstp, info, p);
 729         if (ret < 0)
 730                 goto out;
 731
 732         trace_svcrdma_encode_read(info->ri_chunklen, info->ri_position);
 733
 734         head->rc_hdr_count = 0;
 735
 736         /* Split the Receive buffer between the head and tail
 737          * buffers at Read chunk's position. XDR roundup of the
 738          * chunk is not included in either the pagelist or in
 739          * the tail.
 740          */
 741         head->rc_arg.tail[0].iov_base =
 742                 head->rc_arg.head[0].iov_base + info->ri_position;
 743         head->rc_arg.tail[0].iov_len =
 744                 head->rc_arg.head[0].iov_len - info->ri_position;
 745         head->rc_arg.head[0].iov_len = info->ri_position;
 746
 747         /* Read chunk may need XDR roundup (see RFC 8166, s. 3.4.5.2).
 748          *
 749          * If the client already rounded up the chunk length, the
 750          * length does not change. Otherwise, the length of the page
 751          * list is increased to include XDR round-up.
 752          *
 753          * Currently these chunks always start at page offset 0,
 754          * thus the rounded-up length never crosses a page boundary.
 755          */
 756         info->ri_chunklen = XDR_QUADLEN(info->ri_chunklen) << 2;
 757
 758         head->rc_arg.page_len = info->ri_chunklen;
 759         head->rc_arg.len += info->ri_chunklen;
 760         head->rc_arg.buflen += info->ri_chunklen;
 761
 762 out:
 763         return ret;
 764 }
 765
 766 /* Construct RDMA Reads to pull over a Position Zero Read chunk.
 767  * The start of the data lands in the first page just after
 768  * the Transport header, and the rest lands in the page list of
 769  * head->rc_arg.pages.
 770  *
 771  * Assumptions:
 772  *      - A PZRC has an XDR-aligned length (no implicit round-up).
 773  *      - There can be no trailing inline content (IOW, we assume
 774  *        a PZRC is never sent in an RDMA_MSG message, though it's
 775  *        allowed by spec).
 776  */
 777 static int svc_rdma_build_pz_read_chunk(struct svc_rqst *rqstp,
 778                                         struct svc_rdma_read_info *info,
 779                                         __be32 *p)
 780 {
 781         struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
 782         int ret;
 783
 784         ret = svc_rdma_build_read_chunk(rqstp, info, p);
 785         if (ret < 0)
 786                 goto out;
 787
 788         trace_svcrdma_encode_pzr(info->ri_chunklen);
 789
 790         head->rc_arg.len += info->ri_chunklen;
 791         head->rc_arg.buflen += info->ri_chunklen;
 792
 793         head->rc_hdr_count = 1;
 794         head->rc_arg.head[0].iov_base = page_address(head->rc_pages[0]);
 795         head->rc_arg.head[0].iov_len = min_t(size_t, PAGE_SIZE,
 796                                              info->ri_chunklen);
 797
 798         head->rc_arg.page_len = info->ri_chunklen -
 799                                 head->rc_arg.head[0].iov_len;
 800
 801 out:
 802         return ret;
 803 }
 804
 805 /**
 806  * svc_rdma_recv_read_chunk - Pull a Read chunk from the client
 807  * @rdma: controlling RDMA transport
 808  * @rqstp: set of pages to use as Read sink buffers
 809  * @head: pages under I/O collect here
 810  * @p: pointer to start of Read chunk
 811  *
 812  * Returns:
 813  *      %0 if all needed RDMA Reads were posted successfully,
 814  *      %-EINVAL if client provided too many segments,
 815  *      %-ENOMEM if rdma_rw context pool was exhausted,
 816  *      %-ENOTCONN if posting failed (connection is lost),
 817  *      %-EIO if rdma_rw initialization failed (DMA mapping, etc).
 818  *
 819  * Assumptions:
 820  * - All Read segments in @p have the same Position value.
 821  */
 822 int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp,
 823                              struct svc_rdma_recv_ctxt *head, __be32 *p)
 824 {
 825         struct svc_rdma_read_info *info;
 826         int ret;
 827
 828         /* The request (with page list) is constructed in
 829          * head->rc_arg. Pages involved with RDMA Read I/O are
 830          * transferred there.
 831          */
 832         head->rc_arg.head[0] = rqstp->rq_arg.head[0];
 833         head->rc_arg.tail[0] = rqstp->rq_arg.tail[0];
 834         head->rc_arg.pages = head->rc_pages;
 835         head->rc_arg.page_base = 0;
 836         head->rc_arg.page_len = 0;
 837         head->rc_arg.len = rqstp->rq_arg.len;
 838         head->rc_arg.buflen = rqstp->rq_arg.buflen;
 839
 840         info = svc_rdma_read_info_alloc(rdma);
 841         if (!info)
 842                 return -ENOMEM;
 843         info->ri_readctxt = head;
 844         info->ri_pageno = 0;
 845         info->ri_pageoff = 0;
 846
 847         info->ri_position = be32_to_cpup(p + 1);
 848         if (info->ri_position)
 849                 ret = svc_rdma_build_normal_read_chunk(rqstp, info, p);
 850         else
 851                 ret = svc_rdma_build_pz_read_chunk(rqstp, info, p);
 852         if (ret < 0)
 853                 goto out_err;
 854
 855         ret = svc_rdma_post_chunk_ctxt(&info->ri_cc);
 856         if (ret < 0)
 857                 goto out_err;
 858         return 0;
 859
 860 out_err:
 861         svc_rdma_read_info_free(info);
 862         return ret;
 863 }