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
))
154 f
->fr_pgl
= ib_alloc_fast_reg_page_list(device
, depth
);
155 if (IS_ERR(f
->fr_pgl
))
160 rc
= PTR_ERR(f
->fr_mr
);
161 dprintk("RPC: %s: ib_alloc_mr status %i\n",
166 rc
= PTR_ERR(f
->fr_pgl
);
167 dprintk("RPC: %s: ib_alloc_fast_reg_page_list status %i\n",
169 ib_dereg_mr(f
->fr_mr
);
174 __frwr_release(struct rpcrdma_mw
*r
)
178 rc
= ib_dereg_mr(r
->r
.frmr
.fr_mr
);
180 dprintk("RPC: %s: ib_dereg_mr status %i\n",
182 ib_free_fast_reg_page_list(r
->r
.frmr
.fr_pgl
);
186 frwr_op_open(struct rpcrdma_ia
*ia
, struct rpcrdma_ep
*ep
,
187 struct rpcrdma_create_data_internal
*cdata
)
189 struct ib_device_attr
*devattr
= &ia
->ri_devattr
;
192 ia
->ri_max_frmr_depth
=
193 min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS
,
194 devattr
->max_fast_reg_page_list_len
);
195 dprintk("RPC: %s: device's max FR page list len = %u\n",
196 __func__
, ia
->ri_max_frmr_depth
);
198 /* Add room for frmr register and invalidate WRs.
199 * 1. FRMR reg WR for head
200 * 2. FRMR invalidate WR for head
201 * 3. N FRMR reg WRs for pagelist
202 * 4. N FRMR invalidate WRs for pagelist
203 * 5. FRMR reg WR for tail
204 * 6. FRMR invalidate WR for tail
205 * 7. The RDMA_SEND WR
209 /* Calculate N if the device max FRMR depth is smaller than
210 * RPCRDMA_MAX_DATA_SEGS.
212 if (ia
->ri_max_frmr_depth
< RPCRDMA_MAX_DATA_SEGS
) {
213 delta
= RPCRDMA_MAX_DATA_SEGS
- ia
->ri_max_frmr_depth
;
215 depth
+= 2; /* FRMR reg + invalidate */
216 delta
-= ia
->ri_max_frmr_depth
;
220 ep
->rep_attr
.cap
.max_send_wr
*= depth
;
221 if (ep
->rep_attr
.cap
.max_send_wr
> devattr
->max_qp_wr
) {
222 cdata
->max_requests
= devattr
->max_qp_wr
/ depth
;
223 if (!cdata
->max_requests
)
225 ep
->rep_attr
.cap
.max_send_wr
= cdata
->max_requests
*
232 /* FRWR mode conveys a list of pages per chunk segment. The
233 * maximum length of that list is the FRWR page list depth.
236 frwr_op_maxpages(struct rpcrdma_xprt
*r_xprt
)
238 struct rpcrdma_ia
*ia
= &r_xprt
->rx_ia
;
240 return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS
,
241 rpcrdma_max_segments(r_xprt
) * ia
->ri_max_frmr_depth
);
244 /* If FAST_REG or LOCAL_INV failed, indicate the frmr needs to be reset. */
246 frwr_sendcompletion(struct ib_wc
*wc
)
248 struct rpcrdma_mw
*r
;
250 if (likely(wc
->status
== IB_WC_SUCCESS
))
253 /* WARNING: Only wr_id and status are reliable at this point */
254 r
= (struct rpcrdma_mw
*)(unsigned long)wc
->wr_id
;
255 pr_warn("RPC: %s: frmr %p flushed, status %s (%d)\n",
256 __func__
, r
, ib_wc_status_msg(wc
->status
), wc
->status
);
257 r
->r
.frmr
.fr_state
= FRMR_IS_STALE
;
261 frwr_op_init(struct rpcrdma_xprt
*r_xprt
)
263 struct rpcrdma_buffer
*buf
= &r_xprt
->rx_buf
;
264 struct ib_device
*device
= r_xprt
->rx_ia
.ri_device
;
265 unsigned int depth
= r_xprt
->rx_ia
.ri_max_frmr_depth
;
266 struct ib_pd
*pd
= r_xprt
->rx_ia
.ri_pd
;
269 spin_lock_init(&buf
->rb_mwlock
);
270 INIT_LIST_HEAD(&buf
->rb_mws
);
271 INIT_LIST_HEAD(&buf
->rb_all
);
273 i
= max_t(int, RPCRDMA_MAX_DATA_SEGS
/ depth
, 1);
274 i
+= 2; /* head + tail */
275 i
*= buf
->rb_max_requests
; /* one set for each RPC slot */
276 dprintk("RPC: %s: initalizing %d FRMRs\n", __func__
, i
);
279 struct rpcrdma_mw
*r
;
282 r
= kzalloc(sizeof(*r
), GFP_KERNEL
);
286 rc
= __frwr_init(r
, pd
, device
, depth
);
292 list_add(&r
->mw_list
, &buf
->rb_mws
);
293 list_add(&r
->mw_all
, &buf
->rb_all
);
294 r
->mw_sendcompletion
= frwr_sendcompletion
;
295 r
->r
.frmr
.fr_xprt
= r_xprt
;
301 /* Post a FAST_REG Work Request to register a memory region
302 * for remote access via RDMA READ or RDMA WRITE.
305 frwr_op_map(struct rpcrdma_xprt
*r_xprt
, struct rpcrdma_mr_seg
*seg
,
306 int nsegs
, bool writing
)
308 struct rpcrdma_ia
*ia
= &r_xprt
->rx_ia
;
309 struct ib_device
*device
= ia
->ri_device
;
310 enum dma_data_direction direction
= rpcrdma_data_dir(writing
);
311 struct rpcrdma_mr_seg
*seg1
= seg
;
312 struct rpcrdma_mw
*mw
;
313 struct rpcrdma_frmr
*frmr
;
315 struct ib_send_wr fastreg_wr
, *bad_wr
;
327 __frwr_queue_recovery(mw
);
328 mw
= rpcrdma_get_mw(r_xprt
);
331 } while (mw
->r
.frmr
.fr_state
!= FRMR_IS_INVALID
);
333 frmr
->fr_state
= FRMR_IS_VALID
;
335 pageoff
= offset_in_page(seg1
->mr_offset
);
336 seg1
->mr_offset
-= pageoff
; /* start of page */
337 seg1
->mr_len
+= pageoff
;
339 if (nsegs
> ia
->ri_max_frmr_depth
)
340 nsegs
= ia
->ri_max_frmr_depth
;
342 for (page_no
= i
= 0; i
< nsegs
;) {
343 rpcrdma_map_one(device
, seg
, direction
);
345 for (seg_len
= seg
->mr_len
; seg_len
> 0; seg_len
-= PAGE_SIZE
) {
346 frmr
->fr_pgl
->page_list
[page_no
++] = pa
;
352 /* Check for holes */
353 if ((i
< nsegs
&& offset_in_page(seg
->mr_offset
)) ||
354 offset_in_page((seg
-1)->mr_offset
+ (seg
-1)->mr_len
))
357 dprintk("RPC: %s: Using frmr %p to map %d segments (%d bytes)\n",
358 __func__
, mw
, i
, len
);
360 memset(&fastreg_wr
, 0, sizeof(fastreg_wr
));
361 fastreg_wr
.wr_id
= (unsigned long)(void *)mw
;
362 fastreg_wr
.opcode
= IB_WR_FAST_REG_MR
;
363 fastreg_wr
.wr
.fast_reg
.iova_start
= seg1
->mr_dma
+ pageoff
;
364 fastreg_wr
.wr
.fast_reg
.page_list
= frmr
->fr_pgl
;
365 fastreg_wr
.wr
.fast_reg
.page_shift
= PAGE_SHIFT
;
366 fastreg_wr
.wr
.fast_reg
.page_list_len
= page_no
;
367 fastreg_wr
.wr
.fast_reg
.length
= len
;
368 fastreg_wr
.wr
.fast_reg
.access_flags
= writing
?
369 IB_ACCESS_REMOTE_WRITE
| IB_ACCESS_LOCAL_WRITE
:
370 IB_ACCESS_REMOTE_READ
;
372 key
= (u8
)(mr
->rkey
& 0x000000FF);
373 ib_update_fast_reg_key(mr
, ++key
);
374 fastreg_wr
.wr
.fast_reg
.rkey
= mr
->rkey
;
376 DECR_CQCOUNT(&r_xprt
->rx_ep
);
377 rc
= ib_post_send(ia
->ri_id
->qp
, &fastreg_wr
, &bad_wr
);
382 seg1
->mr_rkey
= mr
->rkey
;
383 seg1
->mr_base
= seg1
->mr_dma
+ pageoff
;
389 dprintk("RPC: %s: ib_post_send status %i\n", __func__
, rc
);
391 rpcrdma_unmap_one(device
, --seg
);
392 __frwr_queue_recovery(mw
);
396 /* Post a LOCAL_INV Work Request to prevent further remote access
397 * via RDMA READ or RDMA WRITE.
400 frwr_op_unmap(struct rpcrdma_xprt
*r_xprt
, struct rpcrdma_mr_seg
*seg
)
402 struct rpcrdma_mr_seg
*seg1
= seg
;
403 struct rpcrdma_ia
*ia
= &r_xprt
->rx_ia
;
404 struct rpcrdma_mw
*mw
= seg1
->rl_mw
;
405 struct ib_send_wr invalidate_wr
, *bad_wr
;
406 int rc
, nsegs
= seg
->mr_nsegs
;
408 dprintk("RPC: %s: FRMR %p\n", __func__
, mw
);
411 mw
->r
.frmr
.fr_state
= FRMR_IS_INVALID
;
413 memset(&invalidate_wr
, 0, sizeof(invalidate_wr
));
414 invalidate_wr
.wr_id
= (unsigned long)(void *)mw
;
415 invalidate_wr
.opcode
= IB_WR_LOCAL_INV
;
416 invalidate_wr
.ex
.invalidate_rkey
= mw
->r
.frmr
.fr_mr
->rkey
;
417 DECR_CQCOUNT(&r_xprt
->rx_ep
);
419 while (seg1
->mr_nsegs
--)
420 rpcrdma_unmap_one(ia
->ri_device
, seg
++);
421 read_lock(&ia
->ri_qplock
);
422 rc
= ib_post_send(ia
->ri_id
->qp
, &invalidate_wr
, &bad_wr
);
423 read_unlock(&ia
->ri_qplock
);
427 rpcrdma_put_mw(r_xprt
, mw
);
431 dprintk("RPC: %s: ib_post_send status %i\n", __func__
, rc
);
432 __frwr_queue_recovery(mw
);
437 frwr_op_destroy(struct rpcrdma_buffer
*buf
)
439 struct rpcrdma_mw
*r
;
441 /* Ensure stale MWs for "buf" are no longer in flight */
442 flush_workqueue(frwr_recovery_wq
);
444 while (!list_empty(&buf
->rb_all
)) {
445 r
= list_entry(buf
->rb_all
.next
, struct rpcrdma_mw
, mw_all
);
446 list_del(&r
->mw_all
);
452 const struct rpcrdma_memreg_ops rpcrdma_frwr_memreg_ops
= {
453 .ro_map
= frwr_op_map
,
454 .ro_unmap
= frwr_op_unmap
,
455 .ro_open
= frwr_op_open
,
456 .ro_maxpages
= frwr_op_maxpages
,
457 .ro_init
= frwr_op_init
,
458 .ro_destroy
= frwr_op_destroy
,
459 .ro_displayname
= "frwr",