4 This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
6 Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
7 Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
8 Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
10 drbd is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2, or (at your option)
15 drbd is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with drbd; see the file COPYING. If not, write to
22 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
26 #include <linux/module.h>
28 #include <linux/slab.h>
29 #include <linux/drbd.h>
34 static bool drbd_may_do_local_read(struct drbd_conf
*mdev
, sector_t sector
, int size
);
36 /* Update disk stats at start of I/O request */
37 static void _drbd_start_io_acct(struct drbd_conf
*mdev
, struct drbd_request
*req
, struct bio
*bio
)
39 const int rw
= bio_data_dir(bio
);
41 cpu
= part_stat_lock();
42 part_round_stats(cpu
, &mdev
->vdisk
->part0
);
43 part_stat_inc(cpu
, &mdev
->vdisk
->part0
, ios
[rw
]);
44 part_stat_add(cpu
, &mdev
->vdisk
->part0
, sectors
[rw
], bio_sectors(bio
));
45 (void) cpu
; /* The macro invocations above want the cpu argument, I do not like
46 the compiler warning about cpu only assigned but never used... */
47 part_inc_in_flight(&mdev
->vdisk
->part0
, rw
);
51 /* Update disk stats when completing request upwards */
52 static void _drbd_end_io_acct(struct drbd_conf
*mdev
, struct drbd_request
*req
)
54 int rw
= bio_data_dir(req
->master_bio
);
55 unsigned long duration
= jiffies
- req
->start_time
;
57 cpu
= part_stat_lock();
58 part_stat_add(cpu
, &mdev
->vdisk
->part0
, ticks
[rw
], duration
);
59 part_round_stats(cpu
, &mdev
->vdisk
->part0
);
60 part_dec_in_flight(&mdev
->vdisk
->part0
, rw
);
64 static struct drbd_request
*drbd_req_new(struct drbd_conf
*mdev
,
67 struct drbd_request
*req
;
69 req
= mempool_alloc(drbd_request_mempool
, GFP_NOIO
);
73 drbd_req_make_private_bio(req
, bio_src
);
74 req
->rq_state
= bio_data_dir(bio_src
) == WRITE
? RQ_WRITE
: 0;
76 req
->master_bio
= bio_src
;
79 drbd_clear_interval(&req
->i
);
80 req
->i
.sector
= bio_src
->bi_sector
;
81 req
->i
.size
= bio_src
->bi_size
;
83 req
->i
.waiting
= false;
85 INIT_LIST_HEAD(&req
->tl_requests
);
86 INIT_LIST_HEAD(&req
->w
.list
);
88 /* one reference to be put by __drbd_make_request */
89 atomic_set(&req
->completion_ref
, 1);
90 /* one kref as long as completion_ref > 0 */
91 kref_init(&req
->kref
);
95 void drbd_req_destroy(struct kref
*kref
)
97 struct drbd_request
*req
= container_of(kref
, struct drbd_request
, kref
);
98 struct drbd_conf
*mdev
= req
->w
.mdev
;
99 const unsigned s
= req
->rq_state
;
101 if ((req
->master_bio
&& !(s
& RQ_POSTPONED
)) ||
102 atomic_read(&req
->completion_ref
) ||
103 (s
& RQ_LOCAL_PENDING
) ||
104 ((s
& RQ_NET_MASK
) && !(s
& RQ_NET_DONE
))) {
105 dev_err(DEV
, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n",
106 s
, atomic_read(&req
->completion_ref
));
110 /* remove it from the transfer log.
111 * well, only if it had been there in the first
112 * place... if it had not (local only or conflicting
113 * and never sent), it should still be "empty" as
114 * initialized in drbd_req_new(), so we can list_del() it
115 * here unconditionally */
116 list_del_init(&req
->tl_requests
);
118 /* if it was a write, we may have to set the corresponding
119 * bit(s) out-of-sync first. If it had a local part, we need to
120 * release the reference to the activity log. */
122 /* Set out-of-sync unless both OK flags are set
123 * (local only or remote failed).
124 * Other places where we set out-of-sync:
125 * READ with local io-error */
127 /* There is a special case:
128 * we may notice late that IO was suspended,
129 * and postpone, or schedule for retry, a write,
130 * before it even was submitted or sent.
131 * In that case we do not want to touch the bitmap at all.
133 if ((s
& (RQ_POSTPONED
|RQ_LOCAL_MASK
|RQ_NET_MASK
)) != RQ_POSTPONED
) {
134 if (!(s
& RQ_NET_OK
) || !(s
& RQ_LOCAL_OK
))
135 drbd_set_out_of_sync(mdev
, req
->i
.sector
, req
->i
.size
);
137 if ((s
& RQ_NET_OK
) && (s
& RQ_LOCAL_OK
) && (s
& RQ_NET_SIS
))
138 drbd_set_in_sync(mdev
, req
->i
.sector
, req
->i
.size
);
141 /* one might be tempted to move the drbd_al_complete_io
142 * to the local io completion callback drbd_request_endio.
143 * but, if this was a mirror write, we may only
144 * drbd_al_complete_io after this is RQ_NET_DONE,
145 * otherwise the extent could be dropped from the al
146 * before it has actually been written on the peer.
147 * if we crash before our peer knows about the request,
148 * but after the extent has been dropped from the al,
149 * we would forget to resync the corresponding extent.
151 if (s
& RQ_IN_ACT_LOG
) {
152 if (get_ldev_if_state(mdev
, D_FAILED
)) {
153 drbd_al_complete_io(mdev
, &req
->i
);
155 } else if (__ratelimit(&drbd_ratelimit_state
)) {
156 dev_warn(DEV
, "Should have called drbd_al_complete_io(, %llu, %u), "
157 "but my Disk seems to have failed :(\n",
158 (unsigned long long) req
->i
.sector
, req
->i
.size
);
163 mempool_free(req
, drbd_request_mempool
);
166 static void wake_all_senders(struct drbd_tconn
*tconn
) {
167 wake_up(&tconn
->sender_work
.q_wait
);
170 /* must hold resource->req_lock */
171 static void start_new_tl_epoch(struct drbd_tconn
*tconn
)
173 /* no point closing an epoch, if it is empty, anyways. */
174 if (tconn
->current_tle_writes
== 0)
177 tconn
->current_tle_writes
= 0;
178 atomic_inc(&tconn
->current_tle_nr
);
179 wake_all_senders(tconn
);
182 void complete_master_bio(struct drbd_conf
*mdev
,
183 struct bio_and_error
*m
)
185 bio_endio(m
->bio
, m
->error
);
190 static void drbd_remove_request_interval(struct rb_root
*root
,
191 struct drbd_request
*req
)
193 struct drbd_conf
*mdev
= req
->w
.mdev
;
194 struct drbd_interval
*i
= &req
->i
;
196 drbd_remove_interval(root
, i
);
198 /* Wake up any processes waiting for this request to complete. */
200 wake_up(&mdev
->misc_wait
);
203 /* Helper for __req_mod().
204 * Set m->bio to the master bio, if it is fit to be completed,
205 * or leave it alone (it is initialized to NULL in __req_mod),
206 * if it has already been completed, or cannot be completed yet.
207 * If m->bio is set, the error status to be returned is placed in m->error.
210 void drbd_req_complete(struct drbd_request
*req
, struct bio_and_error
*m
)
212 const unsigned s
= req
->rq_state
;
213 struct drbd_conf
*mdev
= req
->w
.mdev
;
217 /* we must not complete the master bio, while it is
218 * still being processed by _drbd_send_zc_bio (drbd_send_dblock)
219 * not yet acknowledged by the peer
220 * not yet completed by the local io subsystem
221 * these flags may get cleared in any order by
224 * the bio_endio completion callbacks.
226 if ((s
& RQ_LOCAL_PENDING
&& !(s
& RQ_LOCAL_ABORTED
)) ||
227 (s
& RQ_NET_QUEUED
) || (s
& RQ_NET_PENDING
) ||
228 (s
& RQ_COMPLETION_SUSP
)) {
229 dev_err(DEV
, "drbd_req_complete: Logic BUG rq_state = 0x%x\n", s
);
233 if (!req
->master_bio
) {
234 dev_err(DEV
, "drbd_req_complete: Logic BUG, master_bio == NULL!\n");
238 rw
= bio_rw(req
->master_bio
);
241 * figure out whether to report success or failure.
243 * report success when at least one of the operations succeeded.
244 * or, to put the other way,
245 * only report failure, when both operations failed.
247 * what to do about the failures is handled elsewhere.
248 * what we need to do here is just: complete the master_bio.
250 * local completion error, if any, has been stored as ERR_PTR
251 * in private_bio within drbd_request_endio.
253 ok
= (s
& RQ_LOCAL_OK
) || (s
& RQ_NET_OK
);
254 error
= PTR_ERR(req
->private_bio
);
256 /* remove the request from the conflict detection
257 * respective block_id verification hash */
258 if (!drbd_interval_empty(&req
->i
)) {
259 struct rb_root
*root
;
262 root
= &mdev
->write_requests
;
264 root
= &mdev
->read_requests
;
265 drbd_remove_request_interval(root
, req
);
266 } else if (!(s
& RQ_POSTPONED
))
267 D_ASSERT((s
& (RQ_NET_MASK
& ~RQ_NET_DONE
)) == 0);
269 /* Before we can signal completion to the upper layers,
270 * we may need to close the current transfer log epoch.
271 * We are within the request lock, so we can simply compare
272 * the request epoch number with the current transfer log
273 * epoch number. If they match, increase the current_tle_nr,
274 * and reset the transfer log epoch write_cnt.
277 req
->epoch
== atomic_read(&mdev
->tconn
->current_tle_nr
))
278 start_new_tl_epoch(mdev
->tconn
);
280 /* Update disk stats */
281 _drbd_end_io_acct(mdev
, req
);
284 * have it be pushed back to the retry work queue,
285 * so it will re-enter __drbd_make_request(),
286 * and be re-assigned to a suitable local or remote path,
287 * or failed if we do not have access to good data anymore.
289 * Unless it was failed early by __drbd_make_request(),
290 * because no path was available, in which case
291 * it was not even added to the transfer_log.
293 * READA may fail, and will not be retried.
295 * WRITE should have used all available paths already.
297 if (!ok
&& rw
== READ
&& !list_empty(&req
->tl_requests
))
298 req
->rq_state
|= RQ_POSTPONED
;
300 if (!(req
->rq_state
& RQ_POSTPONED
)) {
301 m
->error
= ok
? 0 : (error
?: -EIO
);
302 m
->bio
= req
->master_bio
;
303 req
->master_bio
= NULL
;
307 static int drbd_req_put_completion_ref(struct drbd_request
*req
, struct bio_and_error
*m
, int put
)
309 struct drbd_conf
*mdev
= req
->w
.mdev
;
310 D_ASSERT(m
|| (req
->rq_state
& RQ_POSTPONED
));
312 if (!atomic_sub_and_test(put
, &req
->completion_ref
))
315 drbd_req_complete(req
, m
);
317 if (req
->rq_state
& RQ_POSTPONED
) {
318 /* don't destroy the req object just yet,
319 * but queue it for retry */
320 drbd_restart_request(req
);
327 /* I'd like this to be the only place that manipulates
328 * req->completion_ref and req->kref. */
329 static void mod_rq_state(struct drbd_request
*req
, struct bio_and_error
*m
,
332 struct drbd_conf
*mdev
= req
->w
.mdev
;
333 unsigned s
= req
->rq_state
;
337 if (drbd_suspended(mdev
) && !((s
| clear
) & RQ_COMPLETION_SUSP
))
338 set
|= RQ_COMPLETION_SUSP
;
342 req
->rq_state
&= ~clear
;
343 req
->rq_state
|= set
;
346 if (req
->rq_state
== s
)
349 /* intent: get references */
351 if (!(s
& RQ_LOCAL_PENDING
) && (set
& RQ_LOCAL_PENDING
))
352 atomic_inc(&req
->completion_ref
);
354 if (!(s
& RQ_NET_PENDING
) && (set
& RQ_NET_PENDING
)) {
355 inc_ap_pending(mdev
);
356 atomic_inc(&req
->completion_ref
);
359 if (!(s
& RQ_NET_QUEUED
) && (set
& RQ_NET_QUEUED
))
360 atomic_inc(&req
->completion_ref
);
362 if (!(s
& RQ_EXP_BARR_ACK
) && (set
& RQ_EXP_BARR_ACK
))
363 kref_get(&req
->kref
); /* wait for the DONE */
365 if (!(s
& RQ_NET_SENT
) && (set
& RQ_NET_SENT
))
366 atomic_add(req
->i
.size
>> 9, &mdev
->ap_in_flight
);
368 if (!(s
& RQ_COMPLETION_SUSP
) && (set
& RQ_COMPLETION_SUSP
))
369 atomic_inc(&req
->completion_ref
);
371 /* progress: put references */
373 if ((s
& RQ_COMPLETION_SUSP
) && (clear
& RQ_COMPLETION_SUSP
))
376 if (!(s
& RQ_LOCAL_ABORTED
) && (set
& RQ_LOCAL_ABORTED
)) {
377 D_ASSERT(req
->rq_state
& RQ_LOCAL_PENDING
);
378 /* local completion may still come in later,
379 * we need to keep the req object around. */
380 kref_get(&req
->kref
);
384 if ((s
& RQ_LOCAL_PENDING
) && (clear
& RQ_LOCAL_PENDING
)) {
385 if (req
->rq_state
& RQ_LOCAL_ABORTED
)
391 if ((s
& RQ_NET_PENDING
) && (clear
& RQ_NET_PENDING
)) {
392 dec_ap_pending(mdev
);
396 if ((s
& RQ_NET_QUEUED
) && (clear
& RQ_NET_QUEUED
))
399 if ((s
& RQ_EXP_BARR_ACK
) && !(s
& RQ_NET_DONE
) && (set
& RQ_NET_DONE
)) {
400 if (req
->rq_state
& RQ_NET_SENT
)
401 atomic_sub(req
->i
.size
>> 9, &mdev
->ap_in_flight
);
405 /* potentially complete and destroy */
407 if (k_put
|| c_put
) {
408 /* Completion does it's own kref_put. If we are going to
409 * kref_sub below, we need req to be still around then. */
410 int at_least
= k_put
+ !!c_put
;
411 int refcount
= atomic_read(&req
->kref
.refcount
);
412 if (refcount
< at_least
)
414 "mod_rq_state: Logic BUG: %x -> %x: refcount = %d, should be >= %d\n",
415 s
, req
->rq_state
, refcount
, at_least
);
418 /* If we made progress, retry conflicting peer requests, if any. */
420 wake_up(&mdev
->misc_wait
);
423 k_put
+= drbd_req_put_completion_ref(req
, m
, c_put
);
425 kref_sub(&req
->kref
, k_put
, drbd_req_destroy
);
428 static void drbd_report_io_error(struct drbd_conf
*mdev
, struct drbd_request
*req
)
430 char b
[BDEVNAME_SIZE
];
432 if (!__ratelimit(&drbd_ratelimit_state
))
435 dev_warn(DEV
, "local %s IO error sector %llu+%u on %s\n",
436 (req
->rq_state
& RQ_WRITE
) ? "WRITE" : "READ",
437 (unsigned long long)req
->i
.sector
,
439 bdevname(mdev
->ldev
->backing_bdev
, b
));
442 /* obviously this could be coded as many single functions
443 * instead of one huge switch,
444 * or by putting the code directly in the respective locations
445 * (as it has been before).
447 * but having it this way
448 * enforces that it is all in this one place, where it is easier to audit,
449 * it makes it obvious that whatever "event" "happens" to a request should
450 * happen "atomically" within the req_lock,
451 * and it enforces that we have to think in a very structured manner
452 * about the "events" that may happen to a request during its life time ...
454 int __req_mod(struct drbd_request
*req
, enum drbd_req_event what
,
455 struct bio_and_error
*m
)
457 struct drbd_conf
*mdev
= req
->w
.mdev
;
466 dev_err(DEV
, "LOGIC BUG in %s:%u\n", __FILE__
, __LINE__
);
469 /* does not happen...
470 * initialization done in drbd_req_new
475 case TO_BE_SENT
: /* via network */
476 /* reached via __drbd_make_request
477 * and from w_read_retry_remote */
478 D_ASSERT(!(req
->rq_state
& RQ_NET_MASK
));
480 nc
= rcu_dereference(mdev
->tconn
->net_conf
);
481 p
= nc
->wire_protocol
;
484 p
== DRBD_PROT_C
? RQ_EXP_WRITE_ACK
:
485 p
== DRBD_PROT_B
? RQ_EXP_RECEIVE_ACK
: 0;
486 mod_rq_state(req
, m
, 0, RQ_NET_PENDING
);
489 case TO_BE_SUBMITTED
: /* locally */
490 /* reached via __drbd_make_request */
491 D_ASSERT(!(req
->rq_state
& RQ_LOCAL_MASK
));
492 mod_rq_state(req
, m
, 0, RQ_LOCAL_PENDING
);
496 if (req
->rq_state
& RQ_WRITE
)
497 mdev
->writ_cnt
+= req
->i
.size
>> 9;
499 mdev
->read_cnt
+= req
->i
.size
>> 9;
501 mod_rq_state(req
, m
, RQ_LOCAL_PENDING
,
502 RQ_LOCAL_COMPLETED
|RQ_LOCAL_OK
);
506 mod_rq_state(req
, m
, 0, RQ_LOCAL_ABORTED
);
509 case WRITE_COMPLETED_WITH_ERROR
:
510 drbd_report_io_error(mdev
, req
);
511 __drbd_chk_io_error(mdev
, DRBD_WRITE_ERROR
);
512 mod_rq_state(req
, m
, RQ_LOCAL_PENDING
, RQ_LOCAL_COMPLETED
);
515 case READ_COMPLETED_WITH_ERROR
:
516 drbd_set_out_of_sync(mdev
, req
->i
.sector
, req
->i
.size
);
517 drbd_report_io_error(mdev
, req
);
518 __drbd_chk_io_error(mdev
, DRBD_READ_ERROR
);
520 case READ_AHEAD_COMPLETED_WITH_ERROR
:
521 /* it is legal to fail READA, no __drbd_chk_io_error in that case. */
522 mod_rq_state(req
, m
, RQ_LOCAL_PENDING
, RQ_LOCAL_COMPLETED
);
525 case QUEUE_FOR_NET_READ
:
526 /* READ or READA, and
528 * or target area marked as invalid,
529 * or just got an io-error. */
530 /* from __drbd_make_request
531 * or from bio_endio during read io-error recovery */
533 /* So we can verify the handle in the answer packet.
534 * Corresponding drbd_remove_request_interval is in
535 * drbd_req_complete() */
536 D_ASSERT(drbd_interval_empty(&req
->i
));
537 drbd_insert_interval(&mdev
->read_requests
, &req
->i
);
539 set_bit(UNPLUG_REMOTE
, &mdev
->flags
);
541 D_ASSERT(req
->rq_state
& RQ_NET_PENDING
);
542 D_ASSERT((req
->rq_state
& RQ_LOCAL_MASK
) == 0);
543 mod_rq_state(req
, m
, 0, RQ_NET_QUEUED
);
544 req
->w
.cb
= w_send_read_req
;
545 drbd_queue_work(&mdev
->tconn
->sender_work
, &req
->w
);
548 case QUEUE_FOR_NET_WRITE
:
549 /* assert something? */
550 /* from __drbd_make_request only */
552 /* Corresponding drbd_remove_request_interval is in
553 * drbd_req_complete() */
554 D_ASSERT(drbd_interval_empty(&req
->i
));
555 drbd_insert_interval(&mdev
->write_requests
, &req
->i
);
558 * In case the req ended up on the transfer log before being
559 * queued on the worker, it could lead to this request being
560 * missed during cleanup after connection loss.
561 * So we have to do both operations here,
562 * within the same lock that protects the transfer log.
564 * _req_add_to_epoch(req); this has to be after the
565 * _maybe_start_new_epoch(req); which happened in
566 * __drbd_make_request, because we now may set the bit
567 * again ourselves to close the current epoch.
569 * Add req to the (now) current epoch (barrier). */
571 /* otherwise we may lose an unplug, which may cause some remote
572 * io-scheduler timeout to expire, increasing maximum latency,
573 * hurting performance. */
574 set_bit(UNPLUG_REMOTE
, &mdev
->flags
);
576 /* queue work item to send data */
577 D_ASSERT(req
->rq_state
& RQ_NET_PENDING
);
578 mod_rq_state(req
, m
, 0, RQ_NET_QUEUED
|RQ_EXP_BARR_ACK
);
579 req
->w
.cb
= w_send_dblock
;
580 drbd_queue_work(&mdev
->tconn
->sender_work
, &req
->w
);
582 /* close the epoch, in case it outgrew the limit */
584 nc
= rcu_dereference(mdev
->tconn
->net_conf
);
585 p
= nc
->max_epoch_size
;
587 if (mdev
->tconn
->current_tle_writes
>= p
)
588 start_new_tl_epoch(mdev
->tconn
);
592 case QUEUE_FOR_SEND_OOS
:
593 mod_rq_state(req
, m
, 0, RQ_NET_QUEUED
);
594 req
->w
.cb
= w_send_out_of_sync
;
595 drbd_queue_work(&mdev
->tconn
->sender_work
, &req
->w
);
598 case READ_RETRY_REMOTE_CANCELED
:
601 /* real cleanup will be done from tl_clear. just update flags
602 * so it is no longer marked as on the worker queue */
603 mod_rq_state(req
, m
, RQ_NET_QUEUED
, 0);
606 case HANDED_OVER_TO_NETWORK
:
607 /* assert something? */
608 if (bio_data_dir(req
->master_bio
) == WRITE
&&
609 !(req
->rq_state
& (RQ_EXP_RECEIVE_ACK
| RQ_EXP_WRITE_ACK
))) {
610 /* this is what is dangerous about protocol A:
611 * pretend it was successfully written on the peer. */
612 if (req
->rq_state
& RQ_NET_PENDING
)
613 mod_rq_state(req
, m
, RQ_NET_PENDING
, RQ_NET_OK
);
614 /* else: neg-ack was faster... */
615 /* it is still not yet RQ_NET_DONE until the
616 * corresponding epoch barrier got acked as well,
617 * so we know what to dirty on connection loss */
619 mod_rq_state(req
, m
, RQ_NET_QUEUED
, RQ_NET_SENT
);
622 case OOS_HANDED_TO_NETWORK
:
623 /* Was not set PENDING, no longer QUEUED, so is now DONE
624 * as far as this connection is concerned. */
625 mod_rq_state(req
, m
, RQ_NET_QUEUED
, RQ_NET_DONE
);
628 case CONNECTION_LOST_WHILE_PENDING
:
629 /* transfer log cleanup after connection loss */
631 RQ_NET_OK
|RQ_NET_PENDING
|RQ_COMPLETION_SUSP
,
635 case CONFLICT_RESOLVED
:
636 /* for superseded conflicting writes of multiple primaries,
637 * there is no need to keep anything in the tl, potential
638 * node crashes are covered by the activity log.
640 * If this request had been marked as RQ_POSTPONED before,
641 * it will actually not be completed, but "restarted",
642 * resubmitted from the retry worker context. */
643 D_ASSERT(req
->rq_state
& RQ_NET_PENDING
);
644 D_ASSERT(req
->rq_state
& RQ_EXP_WRITE_ACK
);
645 mod_rq_state(req
, m
, RQ_NET_PENDING
, RQ_NET_DONE
|RQ_NET_OK
);
648 case WRITE_ACKED_BY_PEER_AND_SIS
:
649 req
->rq_state
|= RQ_NET_SIS
;
650 case WRITE_ACKED_BY_PEER
:
651 D_ASSERT(req
->rq_state
& RQ_EXP_WRITE_ACK
);
652 /* protocol C; successfully written on peer.
653 * Nothing more to do here.
654 * We want to keep the tl in place for all protocols, to cater
655 * for volatile write-back caches on lower level devices. */
658 case RECV_ACKED_BY_PEER
:
659 D_ASSERT(req
->rq_state
& RQ_EXP_RECEIVE_ACK
);
660 /* protocol B; pretends to be successfully written on peer.
661 * see also notes above in HANDED_OVER_TO_NETWORK about
664 D_ASSERT(req
->rq_state
& RQ_NET_PENDING
);
665 mod_rq_state(req
, m
, RQ_NET_PENDING
, RQ_NET_OK
);
669 D_ASSERT(req
->rq_state
& RQ_EXP_WRITE_ACK
);
670 /* If this node has already detected the write conflict, the
671 * worker will be waiting on misc_wait. Wake it up once this
672 * request has completed locally.
674 D_ASSERT(req
->rq_state
& RQ_NET_PENDING
);
675 req
->rq_state
|= RQ_POSTPONED
;
677 wake_up(&mdev
->misc_wait
);
678 /* Do not clear RQ_NET_PENDING. This request will make further
679 * progress via restart_conflicting_writes() or
680 * fail_postponed_requests(). Hopefully. */
684 mod_rq_state(req
, m
, RQ_NET_OK
|RQ_NET_PENDING
, 0);
687 case FAIL_FROZEN_DISK_IO
:
688 if (!(req
->rq_state
& RQ_LOCAL_COMPLETED
))
690 mod_rq_state(req
, m
, RQ_COMPLETION_SUSP
, 0);
693 case RESTART_FROZEN_DISK_IO
:
694 if (!(req
->rq_state
& RQ_LOCAL_COMPLETED
))
698 RQ_COMPLETION_SUSP
|RQ_LOCAL_COMPLETED
,
702 if (bio_data_dir(req
->master_bio
) == WRITE
)
705 get_ldev(mdev
); /* always succeeds in this call path */
706 req
->w
.cb
= w_restart_disk_io
;
707 drbd_queue_work(&mdev
->tconn
->sender_work
, &req
->w
);
711 /* Simply complete (local only) READs. */
712 if (!(req
->rq_state
& RQ_WRITE
) && !req
->w
.cb
) {
713 mod_rq_state(req
, m
, RQ_COMPLETION_SUSP
, 0);
717 /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK
718 before the connection loss (B&C only); only P_BARRIER_ACK
719 (or the local completion?) was missing when we suspended.
720 Throwing them out of the TL here by pretending we got a BARRIER_ACK.
721 During connection handshake, we ensure that the peer was not rebooted. */
722 if (!(req
->rq_state
& RQ_NET_OK
)) {
723 /* FIXME could this possibly be a req->w.cb == w_send_out_of_sync?
724 * in that case we must not set RQ_NET_PENDING. */
726 mod_rq_state(req
, m
, RQ_COMPLETION_SUSP
, RQ_NET_QUEUED
|RQ_NET_PENDING
);
728 drbd_queue_work(&mdev
->tconn
->sender_work
, &req
->w
);
729 rv
= req
->rq_state
& RQ_WRITE
? MR_WRITE
: MR_READ
;
730 } /* else: FIXME can this happen? */
733 /* else, fall through to BARRIER_ACKED */
736 /* barrier ack for READ requests does not make sense */
737 if (!(req
->rq_state
& RQ_WRITE
))
740 if (req
->rq_state
& RQ_NET_PENDING
) {
741 /* barrier came in before all requests were acked.
742 * this is bad, because if the connection is lost now,
743 * we won't be able to clean them up... */
744 dev_err(DEV
, "FIXME (BARRIER_ACKED but pending)\n");
746 /* Allowed to complete requests, even while suspended.
747 * As this is called for all requests within a matching epoch,
748 * we need to filter, and only set RQ_NET_DONE for those that
749 * have actually been on the wire. */
750 mod_rq_state(req
, m
, RQ_COMPLETION_SUSP
,
751 (req
->rq_state
& RQ_NET_MASK
) ? RQ_NET_DONE
: 0);
755 D_ASSERT(req
->rq_state
& RQ_NET_PENDING
);
756 mod_rq_state(req
, m
, RQ_NET_PENDING
, RQ_NET_OK
|RQ_NET_DONE
);
763 /* we may do a local read if:
764 * - we are consistent (of course),
765 * - or we are generally inconsistent,
766 * BUT we are still/already IN SYNC for this area.
767 * since size may be bigger than BM_BLOCK_SIZE,
768 * we may need to check several bits.
770 static bool drbd_may_do_local_read(struct drbd_conf
*mdev
, sector_t sector
, int size
)
772 unsigned long sbnr
, ebnr
;
773 sector_t esector
, nr_sectors
;
775 if (mdev
->state
.disk
== D_UP_TO_DATE
)
777 if (mdev
->state
.disk
!= D_INCONSISTENT
)
779 esector
= sector
+ (size
>> 9) - 1;
780 nr_sectors
= drbd_get_capacity(mdev
->this_bdev
);
781 D_ASSERT(sector
< nr_sectors
);
782 D_ASSERT(esector
< nr_sectors
);
784 sbnr
= BM_SECT_TO_BIT(sector
);
785 ebnr
= BM_SECT_TO_BIT(esector
);
787 return drbd_bm_count_bits(mdev
, sbnr
, ebnr
) == 0;
790 static bool remote_due_to_read_balancing(struct drbd_conf
*mdev
, sector_t sector
,
791 enum drbd_read_balancing rbm
)
793 struct backing_dev_info
*bdi
;
797 case RB_CONGESTED_REMOTE
:
798 bdi
= &mdev
->ldev
->backing_bdev
->bd_disk
->queue
->backing_dev_info
;
799 return bdi_read_congested(bdi
);
800 case RB_LEAST_PENDING
:
801 return atomic_read(&mdev
->local_cnt
) >
802 atomic_read(&mdev
->ap_pending_cnt
) + atomic_read(&mdev
->rs_pending_cnt
);
803 case RB_32K_STRIPING
: /* stripe_shift = 15 */
804 case RB_64K_STRIPING
:
805 case RB_128K_STRIPING
:
806 case RB_256K_STRIPING
:
807 case RB_512K_STRIPING
:
808 case RB_1M_STRIPING
: /* stripe_shift = 20 */
809 stripe_shift
= (rbm
- RB_32K_STRIPING
+ 15);
810 return (sector
>> (stripe_shift
- 9)) & 1;
812 return test_and_change_bit(READ_BALANCE_RR
, &mdev
->flags
);
813 case RB_PREFER_REMOTE
:
815 case RB_PREFER_LOCAL
:
822 * complete_conflicting_writes - wait for any conflicting write requests
824 * The write_requests tree contains all active write requests which we
825 * currently know about. Wait for any requests to complete which conflict with
828 * Only way out: remove the conflicting intervals from the tree.
830 static void complete_conflicting_writes(struct drbd_request
*req
)
833 struct drbd_conf
*mdev
= req
->w
.mdev
;
834 struct drbd_interval
*i
;
835 sector_t sector
= req
->i
.sector
;
836 int size
= req
->i
.size
;
838 i
= drbd_find_overlap(&mdev
->write_requests
, sector
, size
);
843 prepare_to_wait(&mdev
->misc_wait
, &wait
, TASK_UNINTERRUPTIBLE
);
844 i
= drbd_find_overlap(&mdev
->write_requests
, sector
, size
);
847 /* Indicate to wake up device->misc_wait on progress. */
849 spin_unlock_irq(&mdev
->tconn
->req_lock
);
851 spin_lock_irq(&mdev
->tconn
->req_lock
);
853 finish_wait(&mdev
->misc_wait
, &wait
);
856 /* called within req_lock and rcu_read_lock() */
857 static void maybe_pull_ahead(struct drbd_conf
*mdev
)
859 struct drbd_tconn
*tconn
= mdev
->tconn
;
861 bool congested
= false;
862 enum drbd_on_congestion on_congestion
;
864 nc
= rcu_dereference(tconn
->net_conf
);
865 on_congestion
= nc
? nc
->on_congestion
: OC_BLOCK
;
866 if (on_congestion
== OC_BLOCK
||
867 tconn
->agreed_pro_version
< 96)
870 /* If I don't even have good local storage, we can not reasonably try
871 * to pull ahead of the peer. We also need the local reference to make
872 * sure mdev->act_log is there.
874 if (!get_ldev_if_state(mdev
, D_UP_TO_DATE
))
878 atomic_read(&mdev
->ap_in_flight
) >= nc
->cong_fill
) {
879 dev_info(DEV
, "Congestion-fill threshold reached\n");
883 if (mdev
->act_log
->used
>= nc
->cong_extents
) {
884 dev_info(DEV
, "Congestion-extents threshold reached\n");
889 /* start a new epoch for non-mirrored writes */
890 start_new_tl_epoch(mdev
->tconn
);
892 if (on_congestion
== OC_PULL_AHEAD
)
893 _drbd_set_state(_NS(mdev
, conn
, C_AHEAD
), 0, NULL
);
894 else /*nc->on_congestion == OC_DISCONNECT */
895 _drbd_set_state(_NS(mdev
, conn
, C_DISCONNECTING
), 0, NULL
);
900 /* If this returns false, and req->private_bio is still set,
901 * this should be submitted locally.
903 * If it returns false, but req->private_bio is not set,
904 * we do not have access to good data :(
906 * Otherwise, this destroys req->private_bio, if any,
909 static bool do_remote_read(struct drbd_request
*req
)
911 struct drbd_conf
*mdev
= req
->w
.mdev
;
912 enum drbd_read_balancing rbm
;
914 if (req
->private_bio
) {
915 if (!drbd_may_do_local_read(mdev
,
916 req
->i
.sector
, req
->i
.size
)) {
917 bio_put(req
->private_bio
);
918 req
->private_bio
= NULL
;
923 if (mdev
->state
.pdsk
!= D_UP_TO_DATE
)
926 if (req
->private_bio
== NULL
)
929 /* TODO: improve read balancing decisions, take into account drbd
930 * protocol, pending requests etc. */
933 rbm
= rcu_dereference(mdev
->ldev
->disk_conf
)->read_balancing
;
936 if (rbm
== RB_PREFER_LOCAL
&& req
->private_bio
)
937 return false; /* submit locally */
939 if (remote_due_to_read_balancing(mdev
, req
->i
.sector
, rbm
)) {
940 if (req
->private_bio
) {
941 bio_put(req
->private_bio
);
942 req
->private_bio
= NULL
;
951 /* returns number of connections (== 1, for drbd 8.4)
952 * expected to actually write this data,
953 * which does NOT include those that we are L_AHEAD for. */
954 static int drbd_process_write_request(struct drbd_request
*req
)
956 struct drbd_conf
*mdev
= req
->w
.mdev
;
957 int remote
, send_oos
;
960 remote
= drbd_should_do_remote(mdev
->state
);
962 maybe_pull_ahead(mdev
);
963 remote
= drbd_should_do_remote(mdev
->state
);
965 send_oos
= drbd_should_send_out_of_sync(mdev
->state
);
968 /* Need to replicate writes. Unless it is an empty flush,
969 * which is better mapped to a DRBD P_BARRIER packet,
970 * also for drbd wire protocol compatibility reasons.
971 * If this was a flush, just start a new epoch.
972 * Unless the current epoch was empty anyways, or we are not currently
973 * replicating, in which case there is no point. */
974 if (unlikely(req
->i
.size
== 0)) {
975 /* The only size==0 bios we expect are empty flushes. */
976 D_ASSERT(req
->master_bio
->bi_rw
& REQ_FLUSH
);
978 start_new_tl_epoch(mdev
->tconn
);
982 if (!remote
&& !send_oos
)
985 D_ASSERT(!(remote
&& send_oos
));
988 _req_mod(req
, TO_BE_SENT
);
989 _req_mod(req
, QUEUE_FOR_NET_WRITE
);
990 } else if (drbd_set_out_of_sync(mdev
, req
->i
.sector
, req
->i
.size
))
991 _req_mod(req
, QUEUE_FOR_SEND_OOS
);
997 drbd_submit_req_private_bio(struct drbd_request
*req
)
999 struct drbd_conf
*mdev
= req
->w
.mdev
;
1000 struct bio
*bio
= req
->private_bio
;
1001 const int rw
= bio_rw(bio
);
1003 bio
->bi_bdev
= mdev
->ldev
->backing_bdev
;
1005 /* State may have changed since we grabbed our reference on the
1006 * ->ldev member. Double check, and short-circuit to endio.
1007 * In case the last activity log transaction failed to get on
1008 * stable storage, and this is a WRITE, we may not even submit
1010 if (get_ldev(mdev
)) {
1011 if (drbd_insert_fault(mdev
,
1012 rw
== WRITE
? DRBD_FAULT_DT_WR
1013 : rw
== READ
? DRBD_FAULT_DT_RD
1014 : DRBD_FAULT_DT_RA
))
1015 bio_endio(bio
, -EIO
);
1017 generic_make_request(bio
);
1020 bio_endio(bio
, -EIO
);
1023 void __drbd_make_request(struct drbd_conf
*mdev
, struct bio
*bio
, unsigned long start_time
)
1025 const int rw
= bio_rw(bio
);
1026 struct bio_and_error m
= { NULL
, };
1027 struct drbd_request
*req
;
1028 bool no_remote
= false;
1030 /* allocate outside of all locks; */
1031 req
= drbd_req_new(mdev
, bio
);
1034 /* only pass the error to the upper layers.
1035 * if user cannot handle io errors, that's not our business. */
1036 dev_err(DEV
, "could not kmalloc() req\n");
1037 bio_endio(bio
, -ENOMEM
);
1040 req
->start_time
= start_time
;
1042 if (!get_ldev(mdev
)) {
1043 bio_put(req
->private_bio
);
1044 req
->private_bio
= NULL
;
1047 /* For WRITES going to the local disk, grab a reference on the target
1048 * extent. This waits for any resync activity in the corresponding
1049 * resync extent to finish, and, if necessary, pulls in the target
1050 * extent into the activity log, which involves further disk io because
1051 * of transactional on-disk meta data updates.
1052 * Empty flushes don't need to go into the activity log, they can only
1053 * flush data for pending writes which are already in there. */
1054 if (rw
== WRITE
&& req
->private_bio
&& req
->i
.size
1055 && !test_bit(AL_SUSPENDED
, &mdev
->flags
)) {
1056 req
->rq_state
|= RQ_IN_ACT_LOG
;
1057 drbd_al_begin_io(mdev
, &req
->i
);
1060 spin_lock_irq(&mdev
->tconn
->req_lock
);
1062 /* This may temporarily give up the req_lock,
1063 * but will re-aquire it before it returns here.
1064 * Needs to be before the check on drbd_suspended() */
1065 complete_conflicting_writes(req
);
1068 /* no more giving up req_lock from now on! */
1070 if (drbd_suspended(mdev
)) {
1071 /* push back and retry: */
1072 req
->rq_state
|= RQ_POSTPONED
;
1073 if (req
->private_bio
) {
1074 bio_put(req
->private_bio
);
1075 req
->private_bio
= NULL
;
1081 /* Update disk stats */
1082 _drbd_start_io_acct(mdev
, req
, bio
);
1084 /* We fail READ/READA early, if we can not serve it.
1085 * We must do this before req is registered on any lists.
1086 * Otherwise, drbd_req_complete() will queue failed READ for retry. */
1088 if (!do_remote_read(req
) && !req
->private_bio
)
1092 /* which transfer log epoch does this belong to? */
1093 req
->epoch
= atomic_read(&mdev
->tconn
->current_tle_nr
);
1095 /* no point in adding empty flushes to the transfer log,
1096 * they are mapped to drbd barriers already. */
1097 if (likely(req
->i
.size
!=0)) {
1099 mdev
->tconn
->current_tle_writes
++;
1101 list_add_tail(&req
->tl_requests
, &mdev
->tconn
->transfer_log
);
1105 if (!drbd_process_write_request(req
))
1108 /* We either have a private_bio, or we can read from remote.
1109 * Otherwise we had done the goto nodata above. */
1110 if (req
->private_bio
== NULL
) {
1111 _req_mod(req
, TO_BE_SENT
);
1112 _req_mod(req
, QUEUE_FOR_NET_READ
);
1117 if (req
->private_bio
) {
1118 /* needs to be marked within the same spinlock */
1119 _req_mod(req
, TO_BE_SUBMITTED
);
1120 /* but we need to give up the spinlock to submit */
1121 spin_unlock_irq(&mdev
->tconn
->req_lock
);
1122 drbd_submit_req_private_bio(req
);
1123 spin_lock_irq(&mdev
->tconn
->req_lock
);
1124 } else if (no_remote
) {
1126 if (__ratelimit(&drbd_ratelimit_state
))
1127 dev_err(DEV
, "IO ERROR: neither local nor remote data, sector %llu+%u\n",
1128 (unsigned long long)req
->i
.sector
, req
->i
.size
>> 9);
1129 /* A write may have been queued for send_oos, however.
1130 * So we can not simply free it, we must go through drbd_req_put_completion_ref() */
1134 if (drbd_req_put_completion_ref(req
, &m
, 1))
1135 kref_put(&req
->kref
, drbd_req_destroy
);
1136 spin_unlock_irq(&mdev
->tconn
->req_lock
);
1139 complete_master_bio(mdev
, &m
);
1143 void drbd_make_request(struct request_queue
*q
, struct bio
*bio
)
1145 struct drbd_conf
*mdev
= (struct drbd_conf
*) q
->queuedata
;
1146 unsigned long start_time
;
1148 start_time
= jiffies
;
1151 * what we "blindly" assume:
1153 D_ASSERT(IS_ALIGNED(bio
->bi_size
, 512));
1156 __drbd_make_request(mdev
, bio
, start_time
);
1159 /* This is called by bio_add_page().
1161 * q->max_hw_sectors and other global limits are already enforced there.
1163 * We need to call down to our lower level device,
1164 * in case it has special restrictions.
1166 * We also may need to enforce configured max-bio-bvecs limits.
1168 * As long as the BIO is empty we have to allow at least one bvec,
1169 * regardless of size and offset, so no need to ask lower levels.
1171 int drbd_merge_bvec(struct request_queue
*q
, struct bvec_merge_data
*bvm
, struct bio_vec
*bvec
)
1173 struct drbd_conf
*mdev
= (struct drbd_conf
*) q
->queuedata
;
1174 unsigned int bio_size
= bvm
->bi_size
;
1175 int limit
= DRBD_MAX_BIO_SIZE
;
1178 if (bio_size
&& get_ldev(mdev
)) {
1179 struct request_queue
* const b
=
1180 mdev
->ldev
->backing_bdev
->bd_disk
->queue
;
1181 if (b
->merge_bvec_fn
) {
1182 backing_limit
= b
->merge_bvec_fn(b
, bvm
, bvec
);
1183 limit
= min(limit
, backing_limit
);
1190 struct drbd_request
*find_oldest_request(struct drbd_tconn
*tconn
)
1192 /* Walk the transfer log,
1193 * and find the oldest not yet completed request */
1194 struct drbd_request
*r
;
1195 list_for_each_entry(r
, &tconn
->transfer_log
, tl_requests
) {
1196 if (atomic_read(&r
->completion_ref
))
1202 void request_timer_fn(unsigned long data
)
1204 struct drbd_conf
*mdev
= (struct drbd_conf
*) data
;
1205 struct drbd_tconn
*tconn
= mdev
->tconn
;
1206 struct drbd_request
*req
; /* oldest request */
1207 struct net_conf
*nc
;
1208 unsigned long ent
= 0, dt
= 0, et
, nt
; /* effective timeout = ko_count * timeout */
1212 nc
= rcu_dereference(tconn
->net_conf
);
1213 if (nc
&& mdev
->state
.conn
>= C_WF_REPORT_PARAMS
)
1214 ent
= nc
->timeout
* HZ
/10 * nc
->ko_count
;
1216 if (get_ldev(mdev
)) { /* implicit state.disk >= D_INCONSISTENT */
1217 dt
= rcu_dereference(mdev
->ldev
->disk_conf
)->disk_timeout
* HZ
/ 10;
1222 et
= min_not_zero(dt
, ent
);
1225 return; /* Recurring timer stopped */
1229 spin_lock_irq(&tconn
->req_lock
);
1230 req
= find_oldest_request(tconn
);
1232 spin_unlock_irq(&tconn
->req_lock
);
1233 mod_timer(&mdev
->request_timer
, now
+ et
);
1237 /* The request is considered timed out, if
1238 * - we have some effective timeout from the configuration,
1239 * with above state restrictions applied,
1240 * - the oldest request is waiting for a response from the network
1241 * resp. the local disk,
1242 * - the oldest request is in fact older than the effective timeout,
1243 * - the connection was established (resp. disk was attached)
1244 * for longer than the timeout already.
1245 * Note that for 32bit jiffies and very stable connections/disks,
1246 * we may have a wrap around, which is catched by
1247 * !time_in_range(now, last_..._jif, last_..._jif + timeout).
1249 * Side effect: once per 32bit wrap-around interval, which means every
1250 * ~198 days with 250 HZ, we have a window where the timeout would need
1251 * to expire twice (worst case) to become effective. Good enough.
1253 if (ent
&& req
->rq_state
& RQ_NET_PENDING
&&
1254 time_after(now
, req
->start_time
+ ent
) &&
1255 !time_in_range(now
, tconn
->last_reconnect_jif
, tconn
->last_reconnect_jif
+ ent
)) {
1256 dev_warn(DEV
, "Remote failed to finish a request within ko-count * timeout\n");
1257 _drbd_set_state(_NS(mdev
, conn
, C_TIMEOUT
), CS_VERBOSE
| CS_HARD
, NULL
);
1259 if (dt
&& req
->rq_state
& RQ_LOCAL_PENDING
&& req
->w
.mdev
== mdev
&&
1260 time_after(now
, req
->start_time
+ dt
) &&
1261 !time_in_range(now
, mdev
->last_reattach_jif
, mdev
->last_reattach_jif
+ dt
)) {
1262 dev_warn(DEV
, "Local backing device failed to meet the disk-timeout\n");
1263 __drbd_chk_io_error(mdev
, DRBD_FORCE_DETACH
);
1265 nt
= (time_after(now
, req
->start_time
+ et
) ? now
: req
->start_time
) + et
;
1266 spin_unlock_irq(&tconn
->req_lock
);
1267 mod_timer(&mdev
->request_timer
, nt
);