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[];
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(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
71 INIT_LIST_HEAD(&ctxt->rw_list);
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,
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, SG_CHUNK_SIZE);
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);
219 svc_rdma_write_info_free(info);
222 /* State for pulling a Read chunk.
224 struct 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;
231 struct svc_rdma_chunk_ctxt ri_cc;
234 static struct svc_rdma_read_info *
235 svc_rdma_read_info_alloc(struct svcxprt_rdma *rdma)
237 struct svc_rdma_read_info *info;
239 info = kmalloc(sizeof(*info), GFP_KERNEL);
243 svc_rdma_cc_init(rdma, &info->ri_cc);
244 info->ri_cc.cc_cqe.done = svc_rdma_wc_read_done;
248 static void svc_rdma_read_info_free(struct svc_rdma_read_info *info)
250 svc_rdma_cc_release(&info->ri_cc, DMA_FROM_DEVICE);
255 * svc_rdma_wc_read_done - Handle completion of an RDMA Read ctx
256 * @cq: controlling Completion Queue
257 * @wc: Work Completion
260 static void svc_rdma_wc_read_done(struct ib_cq *cq, struct ib_wc *wc)
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);
269 trace_svcrdma_wc_read(wc);
271 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
272 wake_up(&rdma->sc_send_wait);
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);
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);
285 svc_xprt_enqueue(&rdma->sc_xprt);
288 svc_rdma_read_info_free(info);
291 /* This function sleeps when the transport's Send Queue is congested.
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.
298 static int svc_rdma_post_chunk_ctxt(struct svc_rdma_chunk_ctxt *cc)
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;
308 if (cc->cc_sqecount > rdma->sc_sq_depth)
313 list_for_each(tmp, &cc->cc_rwctxts) {
314 struct svc_rdma_rw_ctxt *ctxt;
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);
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);
331 trace_svcrdma_sq_full(rdma);
332 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
333 wait_event(rdma->sc_send_wait,
334 atomic_read(&rdma->sc_sq_avail) > cc->cc_sqecount);
335 trace_svcrdma_sq_retry(rdma);
338 trace_svcrdma_sq_post_err(rdma, ret);
339 set_bit(XPT_CLOSE, &xprt->xpt_flags);
341 /* If even one was posted, there will be a completion. */
342 if (bad_wr != first_wr)
345 atomic_add(cc->cc_sqecount, &rdma->sc_sq_avail);
346 wake_up(&rdma->sc_send_wait);
350 /* Build and DMA-map an SGL that covers one kvec in an xdr_buf
352 static void svc_rdma_vec_to_sg(struct svc_rdma_write_info *info,
354 struct svc_rdma_rw_ctxt *ctxt)
356 struct scatterlist *sg = ctxt->rw_sg_table.sgl;
358 sg_set_buf(&sg[0], info->wi_base, len);
359 info->wi_base += len;
364 /* Build and DMA-map an SGL that covers part of an xdr_buf's pagelist.
366 static void svc_rdma_pagelist_to_sg(struct svc_rdma_write_info *info,
367 unsigned int remaining,
368 struct svc_rdma_rw_ctxt *ctxt)
370 unsigned int sge_no, sge_bytes, page_off, page_no;
371 struct xdr_buf *xdr = info->wi_xdr;
372 struct scatterlist *sg;
375 page_off = info->wi_next_off + xdr->page_base;
376 page_no = page_off >> PAGE_SHIFT;
377 page_off = offset_in_page(page_off);
378 page = xdr->pages + page_no;
379 info->wi_next_off += remaining;
380 sg = ctxt->rw_sg_table.sgl;
383 sge_bytes = min_t(unsigned int, remaining,
384 PAGE_SIZE - page_off);
385 sg_set_page(sg, *page, sge_bytes, page_off);
387 remaining -= sge_bytes;
394 ctxt->rw_nents = sge_no;
397 /* Construct RDMA Write WRs to send a portion of an xdr_buf containing
401 svc_rdma_build_writes(struct svc_rdma_write_info *info,
402 void (*constructor)(struct svc_rdma_write_info *info,
404 struct svc_rdma_rw_ctxt *ctxt),
405 unsigned int remaining)
407 struct svc_rdma_chunk_ctxt *cc = &info->wi_cc;
408 struct svcxprt_rdma *rdma = cc->cc_rdma;
409 struct svc_rdma_rw_ctxt *ctxt;
413 seg = info->wi_segs + info->wi_seg_no * rpcrdma_segment_maxsz;
415 unsigned int write_len;
416 u32 seg_length, seg_handle;
419 if (info->wi_seg_no >= info->wi_nsegs)
422 seg_handle = be32_to_cpup(seg);
423 seg_length = be32_to_cpup(seg + 1);
424 xdr_decode_hyper(seg + 2, &seg_offset);
425 seg_offset += info->wi_seg_off;
427 write_len = min(remaining, seg_length - info->wi_seg_off);
428 ctxt = svc_rdma_get_rw_ctxt(rdma,
429 (write_len >> PAGE_SHIFT) + 2);
433 constructor(info, write_len, ctxt);
434 ret = rdma_rw_ctx_init(&ctxt->rw_ctx, rdma->sc_qp,
435 rdma->sc_port_num, ctxt->rw_sg_table.sgl,
436 ctxt->rw_nents, 0, seg_offset,
437 seg_handle, DMA_TO_DEVICE);
441 trace_svcrdma_send_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) {
448 info->wi_seg_off = 0;
450 info->wi_seg_off += write_len;
452 remaining -= write_len;
458 dprintk("svcrdma: inadequate space in Write chunk (%u)\n",
463 dprintk("svcrdma: no R/W ctxs available\n");
467 svc_rdma_put_rw_ctxt(rdma, ctxt);
468 trace_svcrdma_dma_map_rwctx(rdma, ret);
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.
477 static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
480 info->wi_base = vec->iov_base;
481 return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
485 /* Send an xdr_buf's page list by itself. A Write chunk is just
486 * the page list. A Reply chunk is @xdr's head, page list, and
487 * tail. This function is shared between the two types of chunk.
489 static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
492 unsigned long length)
495 info->wi_next_off = offset - xdr->head[0].iov_len;
496 return svc_rdma_build_writes(info, svc_rdma_pagelist_to_sg,
501 * svc_rdma_send_write_chunk - Write all segments in a Write chunk
502 * @rdma: controlling RDMA transport
503 * @wr_ch: Write chunk provided by client
504 * @xdr: xdr_buf containing the data payload
505 * @offset: payload's byte offset in @xdr
506 * @length: size of payload, in bytes
508 * Returns a non-negative number of bytes the chunk consumed, or
509 * %-E2BIG if the payload was larger than the Write chunk,
510 * %-EINVAL if client provided too many segments,
511 * %-ENOMEM if rdma_rw context pool was exhausted,
512 * %-ENOTCONN if posting failed (connection is lost),
513 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
515 int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
517 unsigned int offset, unsigned long length)
519 struct svc_rdma_write_info *info;
525 info = svc_rdma_write_info_alloc(rdma, wr_ch);
529 ret = svc_rdma_send_xdr_pagelist(info, xdr, offset, length);
533 ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
537 trace_svcrdma_send_write_chunk(xdr->page_len);
541 svc_rdma_write_info_free(info);
546 * svc_rdma_send_reply_chunk - Write all segments in the Reply chunk
547 * @rdma: controlling RDMA transport
548 * @rctxt: Write and Reply chunks from client
549 * @xdr: xdr_buf containing an RPC Reply
551 * Returns a non-negative number of bytes the chunk consumed, or
552 * %-E2BIG if the payload was larger than the Reply chunk,
553 * %-EINVAL if client provided too many segments,
554 * %-ENOMEM if rdma_rw context pool was exhausted,
555 * %-ENOTCONN if posting failed (connection is lost),
556 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
558 int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma,
559 const struct svc_rdma_recv_ctxt *rctxt,
562 struct svc_rdma_write_info *info;
565 info = svc_rdma_write_info_alloc(rdma, rctxt->rc_reply_chunk);
569 ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]);
572 consumed = xdr->head[0].iov_len;
574 /* Send the page list in the Reply chunk only if the
575 * client did not provide Write chunks.
577 if (!rctxt->rc_write_list && xdr->page_len) {
578 ret = svc_rdma_send_xdr_pagelist(info, xdr,
579 xdr->head[0].iov_len,
583 consumed += xdr->page_len;
586 if (xdr->tail[0].iov_len) {
587 ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]);
590 consumed += xdr->tail[0].iov_len;
593 ret = svc_rdma_post_chunk_ctxt(&info->wi_cc);
597 trace_svcrdma_send_reply_chunk(consumed);
601 svc_rdma_write_info_free(info);
605 static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
606 struct svc_rqst *rqstp,
607 u32 rkey, u32 len, u64 offset)
609 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
610 struct svc_rdma_chunk_ctxt *cc = &info->ri_cc;
611 struct svc_rdma_rw_ctxt *ctxt;
612 unsigned int sge_no, seg_len;
613 struct scatterlist *sg;
616 sge_no = PAGE_ALIGN(info->ri_pageoff + len) >> PAGE_SHIFT;
617 ctxt = svc_rdma_get_rw_ctxt(cc->cc_rdma, sge_no);
620 ctxt->rw_nents = sge_no;
622 sg = ctxt->rw_sg_table.sgl;
623 for (sge_no = 0; sge_no < ctxt->rw_nents; sge_no++) {
624 seg_len = min_t(unsigned int, len,
625 PAGE_SIZE - info->ri_pageoff);
627 head->rc_arg.pages[info->ri_pageno] =
628 rqstp->rq_pages[info->ri_pageno];
629 if (!info->ri_pageoff)
630 head->rc_page_count++;
632 sg_set_page(sg, rqstp->rq_pages[info->ri_pageno],
633 seg_len, info->ri_pageoff);
636 info->ri_pageoff += seg_len;
637 if (info->ri_pageoff == PAGE_SIZE) {
639 info->ri_pageoff = 0;
645 &rqstp->rq_pages[info->ri_pageno + 1] > rqstp->rq_page_end)
649 ret = rdma_rw_ctx_init(&ctxt->rw_ctx, cc->cc_rdma->sc_qp,
650 cc->cc_rdma->sc_port_num,
651 ctxt->rw_sg_table.sgl, ctxt->rw_nents,
652 0, offset, rkey, DMA_FROM_DEVICE);
656 list_add(&ctxt->rw_list, &cc->cc_rwctxts);
657 cc->cc_sqecount += ret;
661 dprintk("svcrdma: no R/W ctxs available\n");
665 dprintk("svcrdma: request overruns rq_pages\n");
669 trace_svcrdma_dma_map_rwctx(cc->cc_rdma, ret);
670 svc_rdma_put_rw_ctxt(cc->cc_rdma, ctxt);
674 /* Walk the segments in the Read chunk starting at @p and construct
675 * RDMA Read operations to pull the chunk to the server.
677 static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
678 struct svc_rdma_read_info *info,
685 info->ri_chunklen = 0;
686 while (*p++ != xdr_zero && be32_to_cpup(p++) == info->ri_position) {
687 u32 rs_handle, rs_length;
690 rs_handle = be32_to_cpup(p++);
691 rs_length = be32_to_cpup(p++);
692 p = xdr_decode_hyper(p, &rs_offset);
694 ret = svc_rdma_build_read_segment(info, rqstp,
695 rs_handle, rs_length,
700 trace_svcrdma_send_rseg(rs_handle, rs_length, rs_offset);
701 info->ri_chunklen += rs_length;
704 /* Pages under I/O have been copied to head->rc_pages.
705 * Prevent their premature release by svc_xprt_release() .
707 for (i = 0; i < info->ri_readctxt->rc_page_count; i++)
708 rqstp->rq_pages[i] = NULL;
713 /* Construct RDMA Reads to pull over a normal Read chunk. The chunk
714 * data lands in the page list of head->rc_arg.pages.
716 * Currently NFSD does not look at the head->rc_arg.tail[0] iovec.
717 * Therefore, XDR round-up of the Read chunk and trailing
718 * inline content must both be added at the end of the pagelist.
720 static int svc_rdma_build_normal_read_chunk(struct svc_rqst *rqstp,
721 struct svc_rdma_read_info *info,
724 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
727 ret = svc_rdma_build_read_chunk(rqstp, info, p);
731 trace_svcrdma_send_read_chunk(info->ri_chunklen, info->ri_position);
733 head->rc_hdr_count = 0;
735 /* Split the Receive buffer between the head and tail
736 * buffers at Read chunk's position. XDR roundup of the
737 * chunk is not included in either the pagelist or in
740 head->rc_arg.tail[0].iov_base =
741 head->rc_arg.head[0].iov_base + info->ri_position;
742 head->rc_arg.tail[0].iov_len =
743 head->rc_arg.head[0].iov_len - info->ri_position;
744 head->rc_arg.head[0].iov_len = info->ri_position;
746 /* Read chunk may need XDR roundup (see RFC 8166, s. 3.4.5.2).
748 * If the client already rounded up the chunk length, the
749 * length does not change. Otherwise, the length of the page
750 * list is increased to include XDR round-up.
752 * Currently these chunks always start at page offset 0,
753 * thus the rounded-up length never crosses a page boundary.
755 info->ri_chunklen = XDR_QUADLEN(info->ri_chunklen) << 2;
757 head->rc_arg.page_len = info->ri_chunklen;
758 head->rc_arg.len += info->ri_chunklen;
759 head->rc_arg.buflen += info->ri_chunklen;
765 /* Construct RDMA Reads to pull over a Position Zero Read chunk.
766 * The start of the data lands in the first page just after
767 * the Transport header, and the rest lands in the page list of
768 * head->rc_arg.pages.
771 * - A PZRC has an XDR-aligned length (no implicit round-up).
772 * - There can be no trailing inline content (IOW, we assume
773 * a PZRC is never sent in an RDMA_MSG message, though it's
776 static int svc_rdma_build_pz_read_chunk(struct svc_rqst *rqstp,
777 struct svc_rdma_read_info *info,
780 struct svc_rdma_recv_ctxt *head = info->ri_readctxt;
783 ret = svc_rdma_build_read_chunk(rqstp, info, p);
787 trace_svcrdma_send_pzr(info->ri_chunklen);
789 head->rc_arg.len += info->ri_chunklen;
790 head->rc_arg.buflen += info->ri_chunklen;
792 head->rc_hdr_count = 1;
793 head->rc_arg.head[0].iov_base = page_address(head->rc_pages[0]);
794 head->rc_arg.head[0].iov_len = min_t(size_t, PAGE_SIZE,
797 head->rc_arg.page_len = info->ri_chunklen -
798 head->rc_arg.head[0].iov_len;
805 * svc_rdma_recv_read_chunk - Pull a Read chunk from the client
806 * @rdma: controlling RDMA transport
807 * @rqstp: set of pages to use as Read sink buffers
808 * @head: pages under I/O collect here
809 * @p: pointer to start of Read chunk
812 * %0 if all needed RDMA Reads were posted successfully,
813 * %-EINVAL if client provided too many segments,
814 * %-ENOMEM if rdma_rw context pool was exhausted,
815 * %-ENOTCONN if posting failed (connection is lost),
816 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
819 * - All Read segments in @p have the same Position value.
821 int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp,
822 struct svc_rdma_recv_ctxt *head, __be32 *p)
824 struct svc_rdma_read_info *info;
827 /* The request (with page list) is constructed in
828 * head->rc_arg. Pages involved with RDMA Read I/O are
831 head->rc_arg.head[0] = rqstp->rq_arg.head[0];
832 head->rc_arg.tail[0] = rqstp->rq_arg.tail[0];
833 head->rc_arg.pages = head->rc_pages;
834 head->rc_arg.page_base = 0;
835 head->rc_arg.page_len = 0;
836 head->rc_arg.len = rqstp->rq_arg.len;
837 head->rc_arg.buflen = rqstp->rq_arg.buflen;
839 info = svc_rdma_read_info_alloc(rdma);
842 info->ri_readctxt = head;
844 info->ri_pageoff = 0;
846 info->ri_position = be32_to_cpup(p + 1);
847 if (info->ri_position)
848 ret = svc_rdma_build_normal_read_chunk(rqstp, info, p);
850 ret = svc_rdma_build_pz_read_chunk(rqstp, info, p);
854 ret = svc_rdma_post_chunk_ctxt(&info->ri_cc);
860 svc_rdma_read_info_free(info);