xref: /openbmc/linux/net/sunrpc/xprtrdma/frwr_ops.c (revision 83e025da)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (c) 2015, 2017 Oracle.  All rights reserved.
4  * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
5  */
6 
7 /* Lightweight memory registration using Fast Registration Work
8  * Requests (FRWR).
9  *
10  * FRWR features ordered asynchronous registration and invalidation
11  * of arbitrarily-sized memory regions. This is the fastest and safest
12  * but most complex memory registration mode.
13  */
14 
15 /* Normal operation
16  *
17  * A Memory Region is prepared for RDMA Read or Write using a FAST_REG
18  * Work Request (frwr_map). When the RDMA operation is finished, this
19  * Memory Region is invalidated using a LOCAL_INV Work Request
20  * (frwr_unmap_async and frwr_unmap_sync).
21  *
22  * Typically FAST_REG Work Requests are not signaled, and neither are
23  * RDMA Send Work Requests (with the exception of signaling occasionally
24  * to prevent provider work queue overflows). This greatly reduces HCA
25  * interrupt workload.
26  */
27 
28 /* Transport recovery
29  *
30  * frwr_map and frwr_unmap_* cannot run at the same time the transport
31  * connect worker is running. The connect worker holds the transport
32  * send lock, just as ->send_request does. This prevents frwr_map and
33  * the connect worker from running concurrently. When a connection is
34  * closed, the Receive completion queue is drained before the allowing
35  * the connect worker to get control. This prevents frwr_unmap and the
36  * connect worker from running concurrently.
37  *
38  * When the underlying transport disconnects, MRs that are in flight
39  * are flushed and are likely unusable. Thus all MRs are destroyed.
40  * New MRs are created on demand.
41  */
42 
43 #include <linux/sunrpc/svc_rdma.h>
44 
45 #include "xprt_rdma.h"
46 #include <trace/events/rpcrdma.h>
47 
frwr_cid_init(struct rpcrdma_ep * ep,struct rpcrdma_mr * mr)48 static void frwr_cid_init(struct rpcrdma_ep *ep,
49 			  struct rpcrdma_mr *mr)
50 {
51 	struct rpc_rdma_cid *cid = &mr->mr_cid;
52 
53 	cid->ci_queue_id = ep->re_attr.send_cq->res.id;
54 	cid->ci_completion_id = mr->mr_ibmr->res.id;
55 }
56 
frwr_mr_unmap(struct rpcrdma_xprt * r_xprt,struct rpcrdma_mr * mr)57 static void frwr_mr_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr *mr)
58 {
59 	if (mr->mr_device) {
60 		trace_xprtrdma_mr_unmap(mr);
61 		ib_dma_unmap_sg(mr->mr_device, mr->mr_sg, mr->mr_nents,
62 				mr->mr_dir);
63 		mr->mr_device = NULL;
64 	}
65 }
66 
67 /**
68  * frwr_mr_release - Destroy one MR
69  * @mr: MR allocated by frwr_mr_init
70  *
71  */
frwr_mr_release(struct rpcrdma_mr * mr)72 void frwr_mr_release(struct rpcrdma_mr *mr)
73 {
74 	int rc;
75 
76 	frwr_mr_unmap(mr->mr_xprt, mr);
77 
78 	rc = ib_dereg_mr(mr->mr_ibmr);
79 	if (rc)
80 		trace_xprtrdma_frwr_dereg(mr, rc);
81 	kfree(mr->mr_sg);
82 	kfree(mr);
83 }
84 
frwr_mr_put(struct rpcrdma_mr * mr)85 static void frwr_mr_put(struct rpcrdma_mr *mr)
86 {
87 	frwr_mr_unmap(mr->mr_xprt, mr);
88 
89 	/* The MR is returned to the req's MR free list instead
90 	 * of to the xprt's MR free list. No spinlock is needed.
91 	 */
92 	rpcrdma_mr_push(mr, &mr->mr_req->rl_free_mrs);
93 }
94 
95 /**
96  * frwr_reset - Place MRs back on @req's free list
97  * @req: request to reset
98  *
99  * Used after a failed marshal. For FRWR, this means the MRs
100  * don't have to be fully released and recreated.
101  *
102  * NB: This is safe only as long as none of @req's MRs are
103  * involved with an ongoing asynchronous FAST_REG or LOCAL_INV
104  * Work Request.
105  */
frwr_reset(struct rpcrdma_req * req)106 void frwr_reset(struct rpcrdma_req *req)
107 {
108 	struct rpcrdma_mr *mr;
109 
110 	while ((mr = rpcrdma_mr_pop(&req->rl_registered)))
111 		frwr_mr_put(mr);
112 }
113 
114 /**
115  * frwr_mr_init - Initialize one MR
116  * @r_xprt: controlling transport instance
117  * @mr: generic MR to prepare for FRWR
118  *
119  * Returns zero if successful. Otherwise a negative errno
120  * is returned.
121  */
frwr_mr_init(struct rpcrdma_xprt * r_xprt,struct rpcrdma_mr * mr)122 int frwr_mr_init(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr *mr)
123 {
124 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
125 	unsigned int depth = ep->re_max_fr_depth;
126 	struct scatterlist *sg;
127 	struct ib_mr *frmr;
128 
129 	sg = kcalloc_node(depth, sizeof(*sg), XPRTRDMA_GFP_FLAGS,
130 			  ibdev_to_node(ep->re_id->device));
131 	if (!sg)
132 		return -ENOMEM;
133 
134 	frmr = ib_alloc_mr(ep->re_pd, ep->re_mrtype, depth);
135 	if (IS_ERR(frmr))
136 		goto out_mr_err;
137 
138 	mr->mr_xprt = r_xprt;
139 	mr->mr_ibmr = frmr;
140 	mr->mr_device = NULL;
141 	INIT_LIST_HEAD(&mr->mr_list);
142 	init_completion(&mr->mr_linv_done);
143 	frwr_cid_init(ep, mr);
144 
145 	sg_init_table(sg, depth);
146 	mr->mr_sg = sg;
147 	return 0;
148 
149 out_mr_err:
150 	kfree(sg);
151 	trace_xprtrdma_frwr_alloc(mr, PTR_ERR(frmr));
152 	return PTR_ERR(frmr);
153 }
154 
155 /**
156  * frwr_query_device - Prepare a transport for use with FRWR
157  * @ep: endpoint to fill in
158  * @device: RDMA device to query
159  *
160  * On success, sets:
161  *	ep->re_attr
162  *	ep->re_max_requests
163  *	ep->re_max_rdma_segs
164  *	ep->re_max_fr_depth
165  *	ep->re_mrtype
166  *
167  * Return values:
168  *   On success, returns zero.
169  *   %-EINVAL - the device does not support FRWR memory registration
170  *   %-ENOMEM - the device is not sufficiently capable for NFS/RDMA
171  */
frwr_query_device(struct rpcrdma_ep * ep,const struct ib_device * device)172 int frwr_query_device(struct rpcrdma_ep *ep, const struct ib_device *device)
173 {
174 	const struct ib_device_attr *attrs = &device->attrs;
175 	int max_qp_wr, depth, delta;
176 	unsigned int max_sge;
177 
178 	if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) ||
179 	    attrs->max_fast_reg_page_list_len == 0) {
180 		pr_err("rpcrdma: 'frwr' mode is not supported by device %s\n",
181 		       device->name);
182 		return -EINVAL;
183 	}
184 
185 	max_sge = min_t(unsigned int, attrs->max_send_sge,
186 			RPCRDMA_MAX_SEND_SGES);
187 	if (max_sge < RPCRDMA_MIN_SEND_SGES) {
188 		pr_err("rpcrdma: HCA provides only %u send SGEs\n", max_sge);
189 		return -ENOMEM;
190 	}
191 	ep->re_attr.cap.max_send_sge = max_sge;
192 	ep->re_attr.cap.max_recv_sge = 1;
193 
194 	ep->re_mrtype = IB_MR_TYPE_MEM_REG;
195 	if (attrs->kernel_cap_flags & IBK_SG_GAPS_REG)
196 		ep->re_mrtype = IB_MR_TYPE_SG_GAPS;
197 
198 	/* Quirk: Some devices advertise a large max_fast_reg_page_list_len
199 	 * capability, but perform optimally when the MRs are not larger
200 	 * than a page.
201 	 */
202 	if (attrs->max_sge_rd > RPCRDMA_MAX_HDR_SEGS)
203 		ep->re_max_fr_depth = attrs->max_sge_rd;
204 	else
205 		ep->re_max_fr_depth = attrs->max_fast_reg_page_list_len;
206 	if (ep->re_max_fr_depth > RPCRDMA_MAX_DATA_SEGS)
207 		ep->re_max_fr_depth = RPCRDMA_MAX_DATA_SEGS;
208 
209 	/* Add room for frwr register and invalidate WRs.
210 	 * 1. FRWR reg WR for head
211 	 * 2. FRWR invalidate WR for head
212 	 * 3. N FRWR reg WRs for pagelist
213 	 * 4. N FRWR invalidate WRs for pagelist
214 	 * 5. FRWR reg WR for tail
215 	 * 6. FRWR invalidate WR for tail
216 	 * 7. The RDMA_SEND WR
217 	 */
218 	depth = 7;
219 
220 	/* Calculate N if the device max FRWR depth is smaller than
221 	 * RPCRDMA_MAX_DATA_SEGS.
222 	 */
223 	if (ep->re_max_fr_depth < RPCRDMA_MAX_DATA_SEGS) {
224 		delta = RPCRDMA_MAX_DATA_SEGS - ep->re_max_fr_depth;
225 		do {
226 			depth += 2; /* FRWR reg + invalidate */
227 			delta -= ep->re_max_fr_depth;
228 		} while (delta > 0);
229 	}
230 
231 	max_qp_wr = attrs->max_qp_wr;
232 	max_qp_wr -= RPCRDMA_BACKWARD_WRS;
233 	max_qp_wr -= 1;
234 	if (max_qp_wr < RPCRDMA_MIN_SLOT_TABLE)
235 		return -ENOMEM;
236 	if (ep->re_max_requests > max_qp_wr)
237 		ep->re_max_requests = max_qp_wr;
238 	ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
239 	if (ep->re_attr.cap.max_send_wr > max_qp_wr) {
240 		ep->re_max_requests = max_qp_wr / depth;
241 		if (!ep->re_max_requests)
242 			return -ENOMEM;
243 		ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
244 	}
245 	ep->re_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
246 	ep->re_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
247 	ep->re_attr.cap.max_recv_wr = ep->re_max_requests;
248 	ep->re_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
249 	ep->re_attr.cap.max_recv_wr += RPCRDMA_MAX_RECV_BATCH;
250 	ep->re_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
251 
252 	ep->re_max_rdma_segs =
253 		DIV_ROUND_UP(RPCRDMA_MAX_DATA_SEGS, ep->re_max_fr_depth);
254 	/* Reply chunks require segments for head and tail buffers */
255 	ep->re_max_rdma_segs += 2;
256 	if (ep->re_max_rdma_segs > RPCRDMA_MAX_HDR_SEGS)
257 		ep->re_max_rdma_segs = RPCRDMA_MAX_HDR_SEGS;
258 
259 	/* Ensure the underlying device is capable of conveying the
260 	 * largest r/wsize NFS will ask for. This guarantees that
261 	 * failing over from one RDMA device to another will not
262 	 * break NFS I/O.
263 	 */
264 	if ((ep->re_max_rdma_segs * ep->re_max_fr_depth) < RPCRDMA_MAX_SEGS)
265 		return -ENOMEM;
266 
267 	return 0;
268 }
269 
270 /**
271  * frwr_map - Register a memory region
272  * @r_xprt: controlling transport
273  * @seg: memory region co-ordinates
274  * @nsegs: number of segments remaining
275  * @writing: true when RDMA Write will be used
276  * @xid: XID of RPC using the registered memory
277  * @mr: MR to fill in
278  *
279  * Prepare a REG_MR Work Request to register a memory region
280  * for remote access via RDMA READ or RDMA WRITE.
281  *
282  * Returns the next segment or a negative errno pointer.
283  * On success, @mr is filled in.
284  */
frwr_map(struct rpcrdma_xprt * r_xprt,struct rpcrdma_mr_seg * seg,int nsegs,bool writing,__be32 xid,struct rpcrdma_mr * mr)285 struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
286 				struct rpcrdma_mr_seg *seg,
287 				int nsegs, bool writing, __be32 xid,
288 				struct rpcrdma_mr *mr)
289 {
290 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
291 	struct ib_reg_wr *reg_wr;
292 	int i, n, dma_nents;
293 	struct ib_mr *ibmr;
294 	u8 key;
295 
296 	if (nsegs > ep->re_max_fr_depth)
297 		nsegs = ep->re_max_fr_depth;
298 	for (i = 0; i < nsegs;) {
299 		sg_set_page(&mr->mr_sg[i], seg->mr_page,
300 			    seg->mr_len, seg->mr_offset);
301 
302 		++seg;
303 		++i;
304 		if (ep->re_mrtype == IB_MR_TYPE_SG_GAPS)
305 			continue;
306 		if ((i < nsegs && seg->mr_offset) ||
307 		    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
308 			break;
309 	}
310 	mr->mr_dir = rpcrdma_data_dir(writing);
311 	mr->mr_nents = i;
312 
313 	dma_nents = ib_dma_map_sg(ep->re_id->device, mr->mr_sg, mr->mr_nents,
314 				  mr->mr_dir);
315 	if (!dma_nents)
316 		goto out_dmamap_err;
317 	mr->mr_device = ep->re_id->device;
318 
319 	ibmr = mr->mr_ibmr;
320 	n = ib_map_mr_sg(ibmr, mr->mr_sg, dma_nents, NULL, PAGE_SIZE);
321 	if (n != dma_nents)
322 		goto out_mapmr_err;
323 
324 	ibmr->iova &= 0x00000000ffffffff;
325 	ibmr->iova |= ((u64)be32_to_cpu(xid)) << 32;
326 	key = (u8)(ibmr->rkey & 0x000000FF);
327 	ib_update_fast_reg_key(ibmr, ++key);
328 
329 	reg_wr = &mr->mr_regwr;
330 	reg_wr->mr = ibmr;
331 	reg_wr->key = ibmr->rkey;
332 	reg_wr->access = writing ?
333 			 IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
334 			 IB_ACCESS_REMOTE_READ;
335 
336 	mr->mr_handle = ibmr->rkey;
337 	mr->mr_length = ibmr->length;
338 	mr->mr_offset = ibmr->iova;
339 	trace_xprtrdma_mr_map(mr);
340 
341 	return seg;
342 
343 out_dmamap_err:
344 	trace_xprtrdma_frwr_sgerr(mr, i);
345 	return ERR_PTR(-EIO);
346 
347 out_mapmr_err:
348 	trace_xprtrdma_frwr_maperr(mr, n);
349 	return ERR_PTR(-EIO);
350 }
351 
352 /**
353  * frwr_wc_fastreg - Invoked by RDMA provider for a flushed FastReg WC
354  * @cq: completion queue
355  * @wc: WCE for a completed FastReg WR
356  *
357  * Each flushed MR gets destroyed after the QP has drained.
358  */
frwr_wc_fastreg(struct ib_cq * cq,struct ib_wc * wc)359 static void frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
360 {
361 	struct ib_cqe *cqe = wc->wr_cqe;
362 	struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
363 
364 	/* WARNING: Only wr_cqe and status are reliable at this point */
365 	trace_xprtrdma_wc_fastreg(wc, &mr->mr_cid);
366 
367 	rpcrdma_flush_disconnect(cq->cq_context, wc);
368 }
369 
370 /**
371  * frwr_send - post Send WRs containing the RPC Call message
372  * @r_xprt: controlling transport instance
373  * @req: prepared RPC Call
374  *
375  * For FRWR, chain any FastReg WRs to the Send WR. Only a
376  * single ib_post_send call is needed to register memory
377  * and then post the Send WR.
378  *
379  * Returns the return code from ib_post_send.
380  *
381  * Caller must hold the transport send lock to ensure that the
382  * pointers to the transport's rdma_cm_id and QP are stable.
383  */
frwr_send(struct rpcrdma_xprt * r_xprt,struct rpcrdma_req * req)384 int frwr_send(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
385 {
386 	struct ib_send_wr *post_wr, *send_wr = &req->rl_wr;
387 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
388 	struct rpcrdma_mr *mr;
389 	unsigned int num_wrs;
390 	int ret;
391 
392 	num_wrs = 1;
393 	post_wr = send_wr;
394 	list_for_each_entry(mr, &req->rl_registered, mr_list) {
395 		trace_xprtrdma_mr_fastreg(mr);
396 
397 		mr->mr_cqe.done = frwr_wc_fastreg;
398 		mr->mr_regwr.wr.next = post_wr;
399 		mr->mr_regwr.wr.wr_cqe = &mr->mr_cqe;
400 		mr->mr_regwr.wr.num_sge = 0;
401 		mr->mr_regwr.wr.opcode = IB_WR_REG_MR;
402 		mr->mr_regwr.wr.send_flags = 0;
403 		post_wr = &mr->mr_regwr.wr;
404 		++num_wrs;
405 	}
406 
407 	if ((kref_read(&req->rl_kref) > 1) || num_wrs > ep->re_send_count) {
408 		send_wr->send_flags |= IB_SEND_SIGNALED;
409 		ep->re_send_count = min_t(unsigned int, ep->re_send_batch,
410 					  num_wrs - ep->re_send_count);
411 	} else {
412 		send_wr->send_flags &= ~IB_SEND_SIGNALED;
413 		ep->re_send_count -= num_wrs;
414 	}
415 
416 	trace_xprtrdma_post_send(req);
417 	ret = ib_post_send(ep->re_id->qp, post_wr, NULL);
418 	if (ret)
419 		trace_xprtrdma_post_send_err(r_xprt, req, ret);
420 	return ret;
421 }
422 
423 /**
424  * frwr_reminv - handle a remotely invalidated mr on the @mrs list
425  * @rep: Received reply
426  * @mrs: list of MRs to check
427  *
428  */
frwr_reminv(struct rpcrdma_rep * rep,struct list_head * mrs)429 void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs)
430 {
431 	struct rpcrdma_mr *mr;
432 
433 	list_for_each_entry(mr, mrs, mr_list)
434 		if (mr->mr_handle == rep->rr_inv_rkey) {
435 			list_del_init(&mr->mr_list);
436 			trace_xprtrdma_mr_reminv(mr);
437 			frwr_mr_put(mr);
438 			break;	/* only one invalidated MR per RPC */
439 		}
440 }
441 
frwr_mr_done(struct ib_wc * wc,struct rpcrdma_mr * mr)442 static void frwr_mr_done(struct ib_wc *wc, struct rpcrdma_mr *mr)
443 {
444 	if (likely(wc->status == IB_WC_SUCCESS))
445 		frwr_mr_put(mr);
446 }
447 
448 /**
449  * frwr_wc_localinv - Invoked by RDMA provider for a LOCAL_INV WC
450  * @cq: completion queue
451  * @wc: WCE for a completed LocalInv WR
452  *
453  */
frwr_wc_localinv(struct ib_cq * cq,struct ib_wc * wc)454 static void frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
455 {
456 	struct ib_cqe *cqe = wc->wr_cqe;
457 	struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
458 
459 	/* WARNING: Only wr_cqe and status are reliable at this point */
460 	trace_xprtrdma_wc_li(wc, &mr->mr_cid);
461 	frwr_mr_done(wc, mr);
462 
463 	rpcrdma_flush_disconnect(cq->cq_context, wc);
464 }
465 
466 /**
467  * frwr_wc_localinv_wake - Invoked by RDMA provider for a LOCAL_INV WC
468  * @cq: completion queue
469  * @wc: WCE for a completed LocalInv WR
470  *
471  * Awaken anyone waiting for an MR to finish being fenced.
472  */
frwr_wc_localinv_wake(struct ib_cq * cq,struct ib_wc * wc)473 static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
474 {
475 	struct ib_cqe *cqe = wc->wr_cqe;
476 	struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
477 
478 	/* WARNING: Only wr_cqe and status are reliable at this point */
479 	trace_xprtrdma_wc_li_wake(wc, &mr->mr_cid);
480 	frwr_mr_done(wc, mr);
481 	complete(&mr->mr_linv_done);
482 
483 	rpcrdma_flush_disconnect(cq->cq_context, wc);
484 }
485 
486 /**
487  * frwr_unmap_sync - invalidate memory regions that were registered for @req
488  * @r_xprt: controlling transport instance
489  * @req: rpcrdma_req with a non-empty list of MRs to process
490  *
491  * Sleeps until it is safe for the host CPU to access the previously mapped
492  * memory regions. This guarantees that registered MRs are properly fenced
493  * from the server before the RPC consumer accesses the data in them. It
494  * also ensures proper Send flow control: waking the next RPC waits until
495  * this RPC has relinquished all its Send Queue entries.
496  */
frwr_unmap_sync(struct rpcrdma_xprt * r_xprt,struct rpcrdma_req * req)497 void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
498 {
499 	struct ib_send_wr *first, **prev, *last;
500 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
501 	const struct ib_send_wr *bad_wr;
502 	struct rpcrdma_mr *mr;
503 	int rc;
504 
505 	/* ORDER: Invalidate all of the MRs first
506 	 *
507 	 * Chain the LOCAL_INV Work Requests and post them with
508 	 * a single ib_post_send() call.
509 	 */
510 	prev = &first;
511 	mr = rpcrdma_mr_pop(&req->rl_registered);
512 	do {
513 		trace_xprtrdma_mr_localinv(mr);
514 		r_xprt->rx_stats.local_inv_needed++;
515 
516 		last = &mr->mr_invwr;
517 		last->next = NULL;
518 		last->wr_cqe = &mr->mr_cqe;
519 		last->sg_list = NULL;
520 		last->num_sge = 0;
521 		last->opcode = IB_WR_LOCAL_INV;
522 		last->send_flags = IB_SEND_SIGNALED;
523 		last->ex.invalidate_rkey = mr->mr_handle;
524 
525 		last->wr_cqe->done = frwr_wc_localinv;
526 
527 		*prev = last;
528 		prev = &last->next;
529 	} while ((mr = rpcrdma_mr_pop(&req->rl_registered)));
530 
531 	mr = container_of(last, struct rpcrdma_mr, mr_invwr);
532 
533 	/* Strong send queue ordering guarantees that when the
534 	 * last WR in the chain completes, all WRs in the chain
535 	 * are complete.
536 	 */
537 	last->wr_cqe->done = frwr_wc_localinv_wake;
538 	reinit_completion(&mr->mr_linv_done);
539 
540 	/* Transport disconnect drains the receive CQ before it
541 	 * replaces the QP. The RPC reply handler won't call us
542 	 * unless re_id->qp is a valid pointer.
543 	 */
544 	bad_wr = NULL;
545 	rc = ib_post_send(ep->re_id->qp, first, &bad_wr);
546 
547 	/* The final LOCAL_INV WR in the chain is supposed to
548 	 * do the wake. If it was never posted, the wake will
549 	 * not happen, so don't wait in that case.
550 	 */
551 	if (bad_wr != first)
552 		wait_for_completion(&mr->mr_linv_done);
553 	if (!rc)
554 		return;
555 
556 	/* On error, the MRs get destroyed once the QP has drained. */
557 	trace_xprtrdma_post_linv_err(req, rc);
558 
559 	/* Force a connection loss to ensure complete recovery.
560 	 */
561 	rpcrdma_force_disconnect(ep);
562 }
563 
564 /**
565  * frwr_wc_localinv_done - Invoked by RDMA provider for a signaled LOCAL_INV WC
566  * @cq:	completion queue
567  * @wc:	WCE for a completed LocalInv WR
568  *
569  */
frwr_wc_localinv_done(struct ib_cq * cq,struct ib_wc * wc)570 static void frwr_wc_localinv_done(struct ib_cq *cq, struct ib_wc *wc)
571 {
572 	struct ib_cqe *cqe = wc->wr_cqe;
573 	struct rpcrdma_mr *mr = container_of(cqe, struct rpcrdma_mr, mr_cqe);
574 	struct rpcrdma_rep *rep;
575 
576 	/* WARNING: Only wr_cqe and status are reliable at this point */
577 	trace_xprtrdma_wc_li_done(wc, &mr->mr_cid);
578 
579 	/* Ensure that @rep is generated before the MR is released */
580 	rep = mr->mr_req->rl_reply;
581 	smp_rmb();
582 
583 	if (wc->status != IB_WC_SUCCESS) {
584 		if (rep)
585 			rpcrdma_unpin_rqst(rep);
586 		rpcrdma_flush_disconnect(cq->cq_context, wc);
587 		return;
588 	}
589 	frwr_mr_put(mr);
590 	rpcrdma_complete_rqst(rep);
591 }
592 
593 /**
594  * frwr_unmap_async - invalidate memory regions that were registered for @req
595  * @r_xprt: controlling transport instance
596  * @req: rpcrdma_req with a non-empty list of MRs to process
597  *
598  * This guarantees that registered MRs are properly fenced from the
599  * server before the RPC consumer accesses the data in them. It also
600  * ensures proper Send flow control: waking the next RPC waits until
601  * this RPC has relinquished all its Send Queue entries.
602  */
frwr_unmap_async(struct rpcrdma_xprt * r_xprt,struct rpcrdma_req * req)603 void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
604 {
605 	struct ib_send_wr *first, *last, **prev;
606 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
607 	struct rpcrdma_mr *mr;
608 	int rc;
609 
610 	/* Chain the LOCAL_INV Work Requests and post them with
611 	 * a single ib_post_send() call.
612 	 */
613 	prev = &first;
614 	mr = rpcrdma_mr_pop(&req->rl_registered);
615 	do {
616 		trace_xprtrdma_mr_localinv(mr);
617 		r_xprt->rx_stats.local_inv_needed++;
618 
619 		last = &mr->mr_invwr;
620 		last->next = NULL;
621 		last->wr_cqe = &mr->mr_cqe;
622 		last->sg_list = NULL;
623 		last->num_sge = 0;
624 		last->opcode = IB_WR_LOCAL_INV;
625 		last->send_flags = IB_SEND_SIGNALED;
626 		last->ex.invalidate_rkey = mr->mr_handle;
627 
628 		last->wr_cqe->done = frwr_wc_localinv;
629 
630 		*prev = last;
631 		prev = &last->next;
632 	} while ((mr = rpcrdma_mr_pop(&req->rl_registered)));
633 
634 	/* Strong send queue ordering guarantees that when the
635 	 * last WR in the chain completes, all WRs in the chain
636 	 * are complete. The last completion will wake up the
637 	 * RPC waiter.
638 	 */
639 	last->wr_cqe->done = frwr_wc_localinv_done;
640 
641 	/* Transport disconnect drains the receive CQ before it
642 	 * replaces the QP. The RPC reply handler won't call us
643 	 * unless re_id->qp is a valid pointer.
644 	 */
645 	rc = ib_post_send(ep->re_id->qp, first, NULL);
646 	if (!rc)
647 		return;
648 
649 	/* On error, the MRs get destroyed once the QP has drained. */
650 	trace_xprtrdma_post_linv_err(req, rc);
651 
652 	/* The final LOCAL_INV WR in the chain is supposed to
653 	 * do the wake. If it was never posted, the wake does
654 	 * not happen. Unpin the rqst in preparation for its
655 	 * retransmission.
656 	 */
657 	rpcrdma_unpin_rqst(req->rl_reply);
658 
659 	/* Force a connection loss to ensure complete recovery.
660 	 */
661 	rpcrdma_force_disconnect(ep);
662 }
663 
664 /**
665  * frwr_wp_create - Create an MR for padding Write chunks
666  * @r_xprt: transport resources to use
667  *
668  * Return 0 on success, negative errno on failure.
669  */
frwr_wp_create(struct rpcrdma_xprt * r_xprt)670 int frwr_wp_create(struct rpcrdma_xprt *r_xprt)
671 {
672 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
673 	struct rpcrdma_mr_seg seg;
674 	struct rpcrdma_mr *mr;
675 
676 	mr = rpcrdma_mr_get(r_xprt);
677 	if (!mr)
678 		return -EAGAIN;
679 	mr->mr_req = NULL;
680 	ep->re_write_pad_mr = mr;
681 
682 	seg.mr_len = XDR_UNIT;
683 	seg.mr_page = virt_to_page(ep->re_write_pad);
684 	seg.mr_offset = offset_in_page(ep->re_write_pad);
685 	if (IS_ERR(frwr_map(r_xprt, &seg, 1, true, xdr_zero, mr)))
686 		return -EIO;
687 	trace_xprtrdma_mr_fastreg(mr);
688 
689 	mr->mr_cqe.done = frwr_wc_fastreg;
690 	mr->mr_regwr.wr.next = NULL;
691 	mr->mr_regwr.wr.wr_cqe = &mr->mr_cqe;
692 	mr->mr_regwr.wr.num_sge = 0;
693 	mr->mr_regwr.wr.opcode = IB_WR_REG_MR;
694 	mr->mr_regwr.wr.send_flags = 0;
695 
696 	return ib_post_send(ep->re_id->qp, &mr->mr_regwr.wr, NULL);
697 }
698