2 * Copyright (c) 2015 Oracle. All rights reserved.
3 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
6 /* Lightweight memory registration using Fast Registration Work
7 * Requests (FRWR). Also referred to sometimes as FRMR mode.
9 * FRWR features ordered asynchronous registration and deregistration
10 * of arbitrarily sized memory regions. This is the fastest and safest
11 * but most complex memory registration mode.
16 * A Memory Region is prepared for RDMA READ or WRITE using a FAST_REG
17 * Work Request (frmr_op_map). When the RDMA operation is finished, this
18 * Memory Region is invalidated using a LOCAL_INV Work Request
21 * Typically these Work Requests are not signaled, and neither are RDMA
22 * SEND Work Requests (with the exception of signaling occasionally to
23 * prevent provider work queue overflows). This greatly reduces HCA
26 * As an optimization, frwr_op_unmap marks MRs INVALID before the
27 * LOCAL_INV WR is posted. If posting succeeds, the MR is placed on
28 * rb_mws immediately so that no work (like managing a linked list
29 * under a spinlock) is needed in the completion upcall.
31 * But this means that frwr_op_map() can occasionally encounter an MR
32 * that is INVALID but the LOCAL_INV WR has not completed. Work Queue
33 * ordering prevents a subsequent FAST_REG WR from executing against
34 * that MR while it is still being invalidated.
39 * ->op_map and the transport connect worker cannot run at the same
40 * time, but ->op_unmap can fire while the transport connect worker
41 * is running. Thus MR recovery is handled in ->op_map, to guarantee
42 * that recovered MRs are owned by a sending RPC, and not one where
43 * ->op_unmap could fire at the same time transport reconnect is
46 * When the underlying transport disconnects, MRs are left in one of
49 * INVALID: The MR was not in use before the QP entered ERROR state.
50 * (Or, the LOCAL_INV WR has not completed or flushed yet).
52 * STALE: The MR was being registered or unregistered when the QP
53 * entered ERROR state, and the pending WR was flushed.
55 * VALID: The MR was registered before the QP entered ERROR state.
57 * When frwr_op_map encounters STALE and VALID MRs, they are recovered
58 * with ib_dereg_mr and then are re-initialized. Beause MR recovery
59 * allocates fresh resources, it is deferred to a workqueue, and the
60 * recovered MRs are placed back on the rb_mws list when recovery is
61 * complete. frwr_op_map allocates another MR for the current RPC while
62 * the broken MR is reset.
64 * To ensure that frwr_op_map doesn't encounter an MR that is marked
65 * INVALID but that is about to be flushed due to a previous transport
66 * disconnect, the transport connect worker attempts to drain all
67 * pending send queue WRs before the transport is reconnected.
70 #include "xprt_rdma.h"
72 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
73 # define RPCDBG_FACILITY RPCDBG_TRANS
76 static struct workqueue_struct
*frwr_recovery_wq
;
78 #define FRWR_RECOVERY_WQ_FLAGS (WQ_UNBOUND | WQ_MEM_RECLAIM)
81 frwr_alloc_recovery_wq(void)
83 frwr_recovery_wq
= alloc_workqueue("frwr_recovery",
84 FRWR_RECOVERY_WQ_FLAGS
, 0);
85 return !frwr_recovery_wq
? -ENOMEM
: 0;
89 frwr_destroy_recovery_wq(void)
91 struct workqueue_struct
*wq
;
93 if (!frwr_recovery_wq
)
96 wq
= frwr_recovery_wq
;
97 frwr_recovery_wq
= NULL
;
98 destroy_workqueue(wq
);
101 /* Deferred reset of a single FRMR. Generate a fresh rkey by
104 * There's no recovery if this fails. The FRMR is abandoned, but
105 * remains in rb_all. It will be cleaned up when the transport is
109 __frwr_recovery_worker(struct work_struct
*work
)
111 struct rpcrdma_mw
*r
= container_of(work
, struct rpcrdma_mw
,
113 struct rpcrdma_xprt
*r_xprt
= r
->r
.frmr
.fr_xprt
;
114 unsigned int depth
= r_xprt
->rx_ia
.ri_max_frmr_depth
;
115 struct ib_pd
*pd
= r_xprt
->rx_ia
.ri_pd
;
117 if (ib_dereg_mr(r
->r
.frmr
.fr_mr
))
120 r
->r
.frmr
.fr_mr
= ib_alloc_mr(pd
, IB_MR_TYPE_MEM_REG
, depth
);
121 if (IS_ERR(r
->r
.frmr
.fr_mr
))
124 dprintk("RPC: %s: recovered FRMR %p\n", __func__
, r
);
125 r
->r
.frmr
.fr_state
= FRMR_IS_INVALID
;
126 rpcrdma_put_mw(r_xprt
, r
);
130 pr_warn("RPC: %s: FRMR %p unrecovered\n",
134 /* A broken MR was discovered in a context that can't sleep.
135 * Defer recovery to the recovery worker.
138 __frwr_queue_recovery(struct rpcrdma_mw
*r
)
140 INIT_WORK(&r
->r
.frmr
.fr_work
, __frwr_recovery_worker
);
141 queue_work(frwr_recovery_wq
, &r
->r
.frmr
.fr_work
);
145 __frwr_init(struct rpcrdma_mw
*r
, struct ib_pd
*pd
, struct ib_device
*device
,
148 struct rpcrdma_frmr
*f
= &r
->r
.frmr
;
151 f
->fr_mr
= ib_alloc_mr(pd
, IB_MR_TYPE_MEM_REG
, depth
);
152 if (IS_ERR(f
->fr_mr
))
155 f
->sg
= kcalloc(depth
, sizeof(*f
->sg
), GFP_KERNEL
);
159 sg_init_table(f
->sg
, depth
);
164 rc
= PTR_ERR(f
->fr_mr
);
165 dprintk("RPC: %s: ib_alloc_mr status %i\n",
171 dprintk("RPC: %s: sg allocation failure\n",
173 ib_dereg_mr(f
->fr_mr
);
178 __frwr_release(struct rpcrdma_mw
*r
)
182 rc
= ib_dereg_mr(r
->r
.frmr
.fr_mr
);
184 dprintk("RPC: %s: ib_dereg_mr status %i\n",
190 frwr_op_open(struct rpcrdma_ia
*ia
, struct rpcrdma_ep
*ep
,
191 struct rpcrdma_create_data_internal
*cdata
)
193 struct ib_device_attr
*devattr
= &ia
->ri_devattr
;
196 ia
->ri_max_frmr_depth
=
197 min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS
,
198 devattr
->max_fast_reg_page_list_len
);
199 dprintk("RPC: %s: device's max FR page list len = %u\n",
200 __func__
, ia
->ri_max_frmr_depth
);
202 /* Add room for frmr register and invalidate WRs.
203 * 1. FRMR reg WR for head
204 * 2. FRMR invalidate WR for head
205 * 3. N FRMR reg WRs for pagelist
206 * 4. N FRMR invalidate WRs for pagelist
207 * 5. FRMR reg WR for tail
208 * 6. FRMR invalidate WR for tail
209 * 7. The RDMA_SEND WR
213 /* Calculate N if the device max FRMR depth is smaller than
214 * RPCRDMA_MAX_DATA_SEGS.
216 if (ia
->ri_max_frmr_depth
< RPCRDMA_MAX_DATA_SEGS
) {
217 delta
= RPCRDMA_MAX_DATA_SEGS
- ia
->ri_max_frmr_depth
;
219 depth
+= 2; /* FRMR reg + invalidate */
220 delta
-= ia
->ri_max_frmr_depth
;
224 ep
->rep_attr
.cap
.max_send_wr
*= depth
;
225 if (ep
->rep_attr
.cap
.max_send_wr
> devattr
->max_qp_wr
) {
226 cdata
->max_requests
= devattr
->max_qp_wr
/ depth
;
227 if (!cdata
->max_requests
)
229 ep
->rep_attr
.cap
.max_send_wr
= cdata
->max_requests
*
236 /* FRWR mode conveys a list of pages per chunk segment. The
237 * maximum length of that list is the FRWR page list depth.
240 frwr_op_maxpages(struct rpcrdma_xprt
*r_xprt
)
242 struct rpcrdma_ia
*ia
= &r_xprt
->rx_ia
;
244 return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS
,
245 rpcrdma_max_segments(r_xprt
) * ia
->ri_max_frmr_depth
);
248 /* If FAST_REG or LOCAL_INV failed, indicate the frmr needs to be reset. */
250 frwr_sendcompletion(struct ib_wc
*wc
)
252 struct rpcrdma_mw
*r
;
254 if (likely(wc
->status
== IB_WC_SUCCESS
))
257 /* WARNING: Only wr_id and status are reliable at this point */
258 r
= (struct rpcrdma_mw
*)(unsigned long)wc
->wr_id
;
259 pr_warn("RPC: %s: frmr %p flushed, status %s (%d)\n",
260 __func__
, r
, ib_wc_status_msg(wc
->status
), wc
->status
);
261 r
->r
.frmr
.fr_state
= FRMR_IS_STALE
;
265 frwr_op_init(struct rpcrdma_xprt
*r_xprt
)
267 struct rpcrdma_buffer
*buf
= &r_xprt
->rx_buf
;
268 struct ib_device
*device
= r_xprt
->rx_ia
.ri_device
;
269 unsigned int depth
= r_xprt
->rx_ia
.ri_max_frmr_depth
;
270 struct ib_pd
*pd
= r_xprt
->rx_ia
.ri_pd
;
273 spin_lock_init(&buf
->rb_mwlock
);
274 INIT_LIST_HEAD(&buf
->rb_mws
);
275 INIT_LIST_HEAD(&buf
->rb_all
);
277 i
= max_t(int, RPCRDMA_MAX_DATA_SEGS
/ depth
, 1);
278 i
+= 2; /* head + tail */
279 i
*= buf
->rb_max_requests
; /* one set for each RPC slot */
280 dprintk("RPC: %s: initalizing %d FRMRs\n", __func__
, i
);
283 struct rpcrdma_mw
*r
;
286 r
= kzalloc(sizeof(*r
), GFP_KERNEL
);
290 rc
= __frwr_init(r
, pd
, device
, depth
);
296 list_add(&r
->mw_list
, &buf
->rb_mws
);
297 list_add(&r
->mw_all
, &buf
->rb_all
);
298 r
->mw_sendcompletion
= frwr_sendcompletion
;
299 r
->r
.frmr
.fr_xprt
= r_xprt
;
305 /* Post a FAST_REG Work Request to register a memory region
306 * for remote access via RDMA READ or RDMA WRITE.
309 frwr_op_map(struct rpcrdma_xprt
*r_xprt
, struct rpcrdma_mr_seg
*seg
,
310 int nsegs
, bool writing
)
312 struct rpcrdma_ia
*ia
= &r_xprt
->rx_ia
;
313 struct ib_device
*device
= ia
->ri_device
;
314 enum dma_data_direction direction
= rpcrdma_data_dir(writing
);
315 struct rpcrdma_mr_seg
*seg1
= seg
;
316 struct rpcrdma_mw
*mw
;
317 struct rpcrdma_frmr
*frmr
;
319 struct ib_reg_wr reg_wr
;
320 struct ib_send_wr
*bad_wr
;
321 int rc
, i
, n
, dma_nents
;
328 __frwr_queue_recovery(mw
);
329 mw
= rpcrdma_get_mw(r_xprt
);
332 } while (mw
->r
.frmr
.fr_state
!= FRMR_IS_INVALID
);
334 frmr
->fr_state
= FRMR_IS_VALID
;
337 if (nsegs
> ia
->ri_max_frmr_depth
)
338 nsegs
= ia
->ri_max_frmr_depth
;
340 for (i
= 0; i
< nsegs
;) {
342 sg_set_page(&frmr
->sg
[i
],
345 offset_in_page(seg
->mr_offset
));
347 sg_set_buf(&frmr
->sg
[i
], seg
->mr_offset
,
353 /* Check for holes */
354 if ((i
< nsegs
&& offset_in_page(seg
->mr_offset
)) ||
355 offset_in_page((seg
-1)->mr_offset
+ (seg
-1)->mr_len
))
360 dma_nents
= ib_dma_map_sg(device
, frmr
->sg
, frmr
->sg_nents
, direction
);
362 pr_err("RPC: %s: failed to dma map sg %p sg_nents %u\n",
363 __func__
, frmr
->sg
, frmr
->sg_nents
);
367 n
= ib_map_mr_sg(mr
, frmr
->sg
, frmr
->sg_nents
, PAGE_SIZE
);
368 if (unlikely(n
!= frmr
->sg_nents
)) {
369 pr_err("RPC: %s: failed to map mr %p (%u/%u)\n",
370 __func__
, frmr
->fr_mr
, n
, frmr
->sg_nents
);
371 rc
= n
< 0 ? n
: -EINVAL
;
375 dprintk("RPC: %s: Using frmr %p to map %u segments (%u bytes)\n",
376 __func__
, mw
, frmr
->sg_nents
, mr
->length
);
378 key
= (u8
)(mr
->rkey
& 0x000000FF);
379 ib_update_fast_reg_key(mr
, ++key
);
381 reg_wr
.wr
.next
= NULL
;
382 reg_wr
.wr
.opcode
= IB_WR_REG_MR
;
383 reg_wr
.wr
.wr_id
= (uintptr_t)mw
;
384 reg_wr
.wr
.num_sge
= 0;
385 reg_wr
.wr
.send_flags
= 0;
387 reg_wr
.key
= mr
->rkey
;
388 reg_wr
.access
= writing
?
389 IB_ACCESS_REMOTE_WRITE
| IB_ACCESS_LOCAL_WRITE
:
390 IB_ACCESS_REMOTE_READ
;
392 DECR_CQCOUNT(&r_xprt
->rx_ep
);
393 rc
= ib_post_send(ia
->ri_id
->qp
, ®_wr
.wr
, &bad_wr
);
397 seg1
->mr_dir
= direction
;
399 seg1
->mr_rkey
= mr
->rkey
;
400 seg1
->mr_base
= mr
->iova
;
401 seg1
->mr_nsegs
= frmr
->sg_nents
;
402 seg1
->mr_len
= mr
->length
;
404 return frmr
->sg_nents
;
407 dprintk("RPC: %s: ib_post_send status %i\n", __func__
, rc
);
408 ib_dma_unmap_sg(device
, frmr
->sg
, dma_nents
, direction
);
409 __frwr_queue_recovery(mw
);
413 /* Post a LOCAL_INV Work Request to prevent further remote access
414 * via RDMA READ or RDMA WRITE.
417 frwr_op_unmap(struct rpcrdma_xprt
*r_xprt
, struct rpcrdma_mr_seg
*seg
)
419 struct rpcrdma_mr_seg
*seg1
= seg
;
420 struct rpcrdma_ia
*ia
= &r_xprt
->rx_ia
;
421 struct rpcrdma_mw
*mw
= seg1
->rl_mw
;
422 struct rpcrdma_frmr
*frmr
= &mw
->r
.frmr
;
423 struct ib_send_wr invalidate_wr
, *bad_wr
;
424 int rc
, nsegs
= seg
->mr_nsegs
;
426 dprintk("RPC: %s: FRMR %p\n", __func__
, mw
);
429 frmr
->fr_state
= FRMR_IS_INVALID
;
431 memset(&invalidate_wr
, 0, sizeof(invalidate_wr
));
432 invalidate_wr
.wr_id
= (unsigned long)(void *)mw
;
433 invalidate_wr
.opcode
= IB_WR_LOCAL_INV
;
434 invalidate_wr
.ex
.invalidate_rkey
= frmr
->fr_mr
->rkey
;
435 DECR_CQCOUNT(&r_xprt
->rx_ep
);
437 ib_dma_unmap_sg(ia
->ri_device
, frmr
->sg
, frmr
->sg_nents
, seg1
->mr_dir
);
438 read_lock(&ia
->ri_qplock
);
439 rc
= ib_post_send(ia
->ri_id
->qp
, &invalidate_wr
, &bad_wr
);
440 read_unlock(&ia
->ri_qplock
);
444 rpcrdma_put_mw(r_xprt
, mw
);
448 dprintk("RPC: %s: ib_post_send status %i\n", __func__
, rc
);
449 __frwr_queue_recovery(mw
);
454 frwr_op_destroy(struct rpcrdma_buffer
*buf
)
456 struct rpcrdma_mw
*r
;
458 /* Ensure stale MWs for "buf" are no longer in flight */
459 flush_workqueue(frwr_recovery_wq
);
461 while (!list_empty(&buf
->rb_all
)) {
462 r
= list_entry(buf
->rb_all
.next
, struct rpcrdma_mw
, mw_all
);
463 list_del(&r
->mw_all
);
469 const struct rpcrdma_memreg_ops rpcrdma_frwr_memreg_ops
= {
470 .ro_map
= frwr_op_map
,
471 .ro_unmap
= frwr_op_unmap
,
472 .ro_open
= frwr_op_open
,
473 .ro_maxpages
= frwr_op_maxpages
,
474 .ro_init
= frwr_op_init
,
475 .ro_destroy
= frwr_op_destroy
,
476 .ro_displayname
= "frwr",