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_device *device, sector_t sector, int size);
36 /* Update disk stats at start of I/O request */
37 static void _drbd_start_io_acct(struct drbd_device *device, struct drbd_request *req)
39 generic_start_io_acct(bio_data_dir(req->master_bio), req->i.size >> 9,
40 &device->vdisk->part0);
43 /* Update disk stats when completing request upwards */
44 static void _drbd_end_io_acct(struct drbd_device *device, struct drbd_request *req)
46 generic_end_io_acct(bio_data_dir(req->master_bio),
47 &device->vdisk->part0, req->start_jif);
50 static struct drbd_request *drbd_req_new(struct drbd_device *device,
53 struct drbd_request *req;
55 req = mempool_alloc(drbd_request_mempool, GFP_NOIO | __GFP_ZERO);
59 drbd_req_make_private_bio(req, bio_src);
60 req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0;
62 req->master_bio = bio_src;
65 drbd_clear_interval(&req->i);
66 req->i.sector = bio_src->bi_iter.bi_sector;
67 req->i.size = bio_src->bi_iter.bi_size;
69 req->i.waiting = false;
71 INIT_LIST_HEAD(&req->tl_requests);
72 INIT_LIST_HEAD(&req->w.list);
73 INIT_LIST_HEAD(&req->req_pending_master_completion);
74 INIT_LIST_HEAD(&req->req_pending_local);
76 /* one reference to be put by __drbd_make_request */
77 atomic_set(&req->completion_ref, 1);
78 /* one kref as long as completion_ref > 0 */
79 kref_init(&req->kref);
83 static void drbd_remove_request_interval(struct rb_root *root,
84 struct drbd_request *req)
86 struct drbd_device *device = req->device;
87 struct drbd_interval *i = &req->i;
89 drbd_remove_interval(root, i);
91 /* Wake up any processes waiting for this request to complete. */
93 wake_up(&device->misc_wait);
96 void drbd_req_destroy(struct kref *kref)
98 struct drbd_request *req = container_of(kref, struct drbd_request, kref);
99 struct drbd_device *device = req->device;
100 const unsigned s = req->rq_state;
102 if ((req->master_bio && !(s & RQ_POSTPONED)) ||
103 atomic_read(&req->completion_ref) ||
104 (s & RQ_LOCAL_PENDING) ||
105 ((s & RQ_NET_MASK) && !(s & RQ_NET_DONE))) {
106 drbd_err(device, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n",
107 s, atomic_read(&req->completion_ref));
111 /* If called from mod_rq_state (expected normal case) or
112 * drbd_send_and_submit (the less likely normal path), this holds the
113 * req_lock, and req->tl_requests will typicaly be on ->transfer_log,
114 * though it may be still empty (never added to the transfer log).
116 * If called from do_retry(), we do NOT hold the req_lock, but we are
117 * still allowed to unconditionally list_del(&req->tl_requests),
118 * because it will be on a local on-stack list only. */
119 list_del_init(&req->tl_requests);
121 /* finally remove the request from the conflict detection
122 * respective block_id verification interval tree. */
123 if (!drbd_interval_empty(&req->i)) {
124 struct rb_root *root;
127 root = &device->write_requests;
129 root = &device->read_requests;
130 drbd_remove_request_interval(root, req);
131 } else if (s & (RQ_NET_MASK & ~RQ_NET_DONE) && req->i.size != 0)
132 drbd_err(device, "drbd_req_destroy: Logic BUG: interval empty, but: rq_state=0x%x, sect=%llu, size=%u\n",
133 s, (unsigned long long)req->i.sector, req->i.size);
135 /* if it was a write, we may have to set the corresponding
136 * bit(s) out-of-sync first. If it had a local part, we need to
137 * release the reference to the activity log. */
139 /* Set out-of-sync unless both OK flags are set
140 * (local only or remote failed).
141 * Other places where we set out-of-sync:
142 * READ with local io-error */
144 /* There is a special case:
145 * we may notice late that IO was suspended,
146 * and postpone, or schedule for retry, a write,
147 * before it even was submitted or sent.
148 * In that case we do not want to touch the bitmap at all.
150 if ((s & (RQ_POSTPONED|RQ_LOCAL_MASK|RQ_NET_MASK)) != RQ_POSTPONED) {
151 if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK))
152 drbd_set_out_of_sync(device, req->i.sector, req->i.size);
154 if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS))
155 drbd_set_in_sync(device, req->i.sector, req->i.size);
158 /* one might be tempted to move the drbd_al_complete_io
159 * to the local io completion callback drbd_request_endio.
160 * but, if this was a mirror write, we may only
161 * drbd_al_complete_io after this is RQ_NET_DONE,
162 * otherwise the extent could be dropped from the al
163 * before it has actually been written on the peer.
164 * if we crash before our peer knows about the request,
165 * but after the extent has been dropped from the al,
166 * we would forget to resync the corresponding extent.
168 if (s & RQ_IN_ACT_LOG) {
169 if (get_ldev_if_state(device, D_FAILED)) {
170 drbd_al_complete_io(device, &req->i);
172 } else if (__ratelimit(&drbd_ratelimit_state)) {
173 drbd_warn(device, "Should have called drbd_al_complete_io(, %llu, %u), "
174 "but my Disk seems to have failed :(\n",
175 (unsigned long long) req->i.sector, req->i.size);
180 mempool_free(req, drbd_request_mempool);
183 static void wake_all_senders(struct drbd_connection *connection)
185 wake_up(&connection->sender_work.q_wait);
188 /* must hold resource->req_lock */
189 void start_new_tl_epoch(struct drbd_connection *connection)
191 /* no point closing an epoch, if it is empty, anyways. */
192 if (connection->current_tle_writes == 0)
195 connection->current_tle_writes = 0;
196 atomic_inc(&connection->current_tle_nr);
197 wake_all_senders(connection);
200 void complete_master_bio(struct drbd_device *device,
201 struct bio_and_error *m)
203 bio_endio(m->bio, m->error);
208 /* Helper for __req_mod().
209 * Set m->bio to the master bio, if it is fit to be completed,
210 * or leave it alone (it is initialized to NULL in __req_mod),
211 * if it has already been completed, or cannot be completed yet.
212 * If m->bio is set, the error status to be returned is placed in m->error.
215 void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
217 const unsigned s = req->rq_state;
218 struct drbd_device *device = req->device;
222 /* we must not complete the master bio, while it is
223 * still being processed by _drbd_send_zc_bio (drbd_send_dblock)
224 * not yet acknowledged by the peer
225 * not yet completed by the local io subsystem
226 * these flags may get cleared in any order by
229 * the bio_endio completion callbacks.
231 if ((s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED)) ||
232 (s & RQ_NET_QUEUED) || (s & RQ_NET_PENDING) ||
233 (s & RQ_COMPLETION_SUSP)) {
234 drbd_err(device, "drbd_req_complete: Logic BUG rq_state = 0x%x\n", s);
238 if (!req->master_bio) {
239 drbd_err(device, "drbd_req_complete: Logic BUG, master_bio == NULL!\n");
243 rw = bio_rw(req->master_bio);
246 * figure out whether to report success or failure.
248 * report success when at least one of the operations succeeded.
249 * or, to put the other way,
250 * only report failure, when both operations failed.
252 * what to do about the failures is handled elsewhere.
253 * what we need to do here is just: complete the master_bio.
255 * local completion error, if any, has been stored as ERR_PTR
256 * in private_bio within drbd_request_endio.
258 ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK);
259 error = PTR_ERR(req->private_bio);
261 /* Before we can signal completion to the upper layers,
262 * we may need to close the current transfer log epoch.
263 * We are within the request lock, so we can simply compare
264 * the request epoch number with the current transfer log
265 * epoch number. If they match, increase the current_tle_nr,
266 * and reset the transfer log epoch write_cnt.
269 req->epoch == atomic_read(&first_peer_device(device)->connection->current_tle_nr))
270 start_new_tl_epoch(first_peer_device(device)->connection);
272 /* Update disk stats */
273 _drbd_end_io_acct(device, req);
276 * have it be pushed back to the retry work queue,
277 * so it will re-enter __drbd_make_request(),
278 * and be re-assigned to a suitable local or remote path,
279 * or failed if we do not have access to good data anymore.
281 * Unless it was failed early by __drbd_make_request(),
282 * because no path was available, in which case
283 * it was not even added to the transfer_log.
285 * READA may fail, and will not be retried.
287 * WRITE should have used all available paths already.
289 if (!ok && rw == READ && !list_empty(&req->tl_requests))
290 req->rq_state |= RQ_POSTPONED;
292 if (!(req->rq_state & RQ_POSTPONED)) {
293 m->error = ok ? 0 : (error ?: -EIO);
294 m->bio = req->master_bio;
295 req->master_bio = NULL;
296 /* We leave it in the tree, to be able to verify later
297 * write-acks in protocol != C during resync.
298 * But we mark it as "complete", so it won't be counted as
299 * conflict in a multi-primary setup. */
300 req->i.completed = true;
304 wake_up(&device->misc_wait);
306 /* Either we are about to complete to upper layers,
307 * or we will restart this request.
308 * In either case, the request object will be destroyed soon,
309 * so better remove it from all lists. */
310 list_del_init(&req->req_pending_master_completion);
313 /* still holds resource->req_lock */
314 static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put)
316 struct drbd_device *device = req->device;
317 D_ASSERT(device, m || (req->rq_state & RQ_POSTPONED));
319 if (!atomic_sub_and_test(put, &req->completion_ref))
322 drbd_req_complete(req, m);
324 if (req->rq_state & RQ_POSTPONED) {
325 /* don't destroy the req object just yet,
326 * but queue it for retry */
327 drbd_restart_request(req);
334 static void set_if_null_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req)
336 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
339 if (connection->req_next == NULL)
340 connection->req_next = req;
343 static void advance_conn_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req)
345 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
348 if (connection->req_next != req)
350 list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
351 const unsigned s = req->rq_state;
352 if (s & RQ_NET_QUEUED)
355 if (&req->tl_requests == &connection->transfer_log)
357 connection->req_next = req;
360 static void set_if_null_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req)
362 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
365 if (connection->req_ack_pending == NULL)
366 connection->req_ack_pending = req;
369 static void advance_conn_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req)
371 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
374 if (connection->req_ack_pending != req)
376 list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
377 const unsigned s = req->rq_state;
378 if ((s & RQ_NET_SENT) && (s & RQ_NET_PENDING))
381 if (&req->tl_requests == &connection->transfer_log)
383 connection->req_ack_pending = req;
386 static void set_if_null_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req)
388 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
391 if (connection->req_not_net_done == NULL)
392 connection->req_not_net_done = req;
395 static void advance_conn_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req)
397 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
400 if (connection->req_not_net_done != req)
402 list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
403 const unsigned s = req->rq_state;
404 if ((s & RQ_NET_SENT) && !(s & RQ_NET_DONE))
407 if (&req->tl_requests == &connection->transfer_log)
409 connection->req_not_net_done = req;
412 /* I'd like this to be the only place that manipulates
413 * req->completion_ref and req->kref. */
414 static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
417 struct drbd_device *device = req->device;
418 struct drbd_peer_device *peer_device = first_peer_device(device);
419 unsigned s = req->rq_state;
423 if (drbd_suspended(device) && !((s | clear) & RQ_COMPLETION_SUSP))
424 set |= RQ_COMPLETION_SUSP;
428 req->rq_state &= ~clear;
429 req->rq_state |= set;
432 if (req->rq_state == s)
435 /* intent: get references */
437 if (!(s & RQ_LOCAL_PENDING) && (set & RQ_LOCAL_PENDING))
438 atomic_inc(&req->completion_ref);
440 if (!(s & RQ_NET_PENDING) && (set & RQ_NET_PENDING)) {
441 inc_ap_pending(device);
442 atomic_inc(&req->completion_ref);
445 if (!(s & RQ_NET_QUEUED) && (set & RQ_NET_QUEUED)) {
446 atomic_inc(&req->completion_ref);
447 set_if_null_req_next(peer_device, req);
450 if (!(s & RQ_EXP_BARR_ACK) && (set & RQ_EXP_BARR_ACK))
451 kref_get(&req->kref); /* wait for the DONE */
453 if (!(s & RQ_NET_SENT) && (set & RQ_NET_SENT)) {
454 /* potentially already completed in the asender thread */
455 if (!(s & RQ_NET_DONE)) {
456 atomic_add(req->i.size >> 9, &device->ap_in_flight);
457 set_if_null_req_not_net_done(peer_device, req);
459 if (s & RQ_NET_PENDING)
460 set_if_null_req_ack_pending(peer_device, req);
463 if (!(s & RQ_COMPLETION_SUSP) && (set & RQ_COMPLETION_SUSP))
464 atomic_inc(&req->completion_ref);
466 /* progress: put references */
468 if ((s & RQ_COMPLETION_SUSP) && (clear & RQ_COMPLETION_SUSP))
471 if (!(s & RQ_LOCAL_ABORTED) && (set & RQ_LOCAL_ABORTED)) {
472 D_ASSERT(device, req->rq_state & RQ_LOCAL_PENDING);
473 /* local completion may still come in later,
474 * we need to keep the req object around. */
475 kref_get(&req->kref);
479 if ((s & RQ_LOCAL_PENDING) && (clear & RQ_LOCAL_PENDING)) {
480 if (req->rq_state & RQ_LOCAL_ABORTED)
484 list_del_init(&req->req_pending_local);
487 if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) {
488 dec_ap_pending(device);
490 req->acked_jif = jiffies;
491 advance_conn_req_ack_pending(peer_device, req);
494 if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED)) {
496 advance_conn_req_next(peer_device, req);
499 if (!(s & RQ_NET_DONE) && (set & RQ_NET_DONE)) {
501 atomic_sub(req->i.size >> 9, &device->ap_in_flight);
502 if (s & RQ_EXP_BARR_ACK)
504 req->net_done_jif = jiffies;
506 /* in ahead/behind mode, or just in case,
507 * before we finally destroy this request,
508 * the caching pointers must not reference it anymore */
509 advance_conn_req_next(peer_device, req);
510 advance_conn_req_ack_pending(peer_device, req);
511 advance_conn_req_not_net_done(peer_device, req);
514 /* potentially complete and destroy */
516 if (k_put || c_put) {
517 /* Completion does it's own kref_put. If we are going to
518 * kref_sub below, we need req to be still around then. */
519 int at_least = k_put + !!c_put;
520 int refcount = atomic_read(&req->kref.refcount);
521 if (refcount < at_least)
523 "mod_rq_state: Logic BUG: %x -> %x: refcount = %d, should be >= %d\n",
524 s, req->rq_state, refcount, at_least);
527 /* If we made progress, retry conflicting peer requests, if any. */
529 wake_up(&device->misc_wait);
532 k_put += drbd_req_put_completion_ref(req, m, c_put);
534 kref_sub(&req->kref, k_put, drbd_req_destroy);
537 static void drbd_report_io_error(struct drbd_device *device, struct drbd_request *req)
539 char b[BDEVNAME_SIZE];
541 if (!__ratelimit(&drbd_ratelimit_state))
544 drbd_warn(device, "local %s IO error sector %llu+%u on %s\n",
545 (req->rq_state & RQ_WRITE) ? "WRITE" : "READ",
546 (unsigned long long)req->i.sector,
548 bdevname(device->ldev->backing_bdev, b));
551 /* Helper for HANDED_OVER_TO_NETWORK.
552 * Is this a protocol A write (neither WRITE_ACK nor RECEIVE_ACK expected)?
553 * Is it also still "PENDING"?
554 * --> If so, clear PENDING and set NET_OK below.
555 * If it is a protocol A write, but not RQ_PENDING anymore, neg-ack was faster
556 * (and we must not set RQ_NET_OK) */
557 static inline bool is_pending_write_protocol_A(struct drbd_request *req)
559 return (req->rq_state &
560 (RQ_WRITE|RQ_NET_PENDING|RQ_EXP_WRITE_ACK|RQ_EXP_RECEIVE_ACK))
561 == (RQ_WRITE|RQ_NET_PENDING);
564 /* obviously this could be coded as many single functions
565 * instead of one huge switch,
566 * or by putting the code directly in the respective locations
567 * (as it has been before).
569 * but having it this way
570 * enforces that it is all in this one place, where it is easier to audit,
571 * it makes it obvious that whatever "event" "happens" to a request should
572 * happen "atomically" within the req_lock,
573 * and it enforces that we have to think in a very structured manner
574 * about the "events" that may happen to a request during its life time ...
576 int __req_mod(struct drbd_request *req, enum drbd_req_event what,
577 struct bio_and_error *m)
579 struct drbd_device *const device = req->device;
580 struct drbd_peer_device *const peer_device = first_peer_device(device);
581 struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL;
590 drbd_err(device, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__);
593 /* does not happen...
594 * initialization done in drbd_req_new
599 case TO_BE_SENT: /* via network */
600 /* reached via __drbd_make_request
601 * and from w_read_retry_remote */
602 D_ASSERT(device, !(req->rq_state & RQ_NET_MASK));
604 nc = rcu_dereference(connection->net_conf);
605 p = nc->wire_protocol;
608 p == DRBD_PROT_C ? RQ_EXP_WRITE_ACK :
609 p == DRBD_PROT_B ? RQ_EXP_RECEIVE_ACK : 0;
610 mod_rq_state(req, m, 0, RQ_NET_PENDING);
613 case TO_BE_SUBMITTED: /* locally */
614 /* reached via __drbd_make_request */
615 D_ASSERT(device, !(req->rq_state & RQ_LOCAL_MASK));
616 mod_rq_state(req, m, 0, RQ_LOCAL_PENDING);
620 if (req->rq_state & RQ_WRITE)
621 device->writ_cnt += req->i.size >> 9;
623 device->read_cnt += req->i.size >> 9;
625 mod_rq_state(req, m, RQ_LOCAL_PENDING,
626 RQ_LOCAL_COMPLETED|RQ_LOCAL_OK);
630 mod_rq_state(req, m, 0, RQ_LOCAL_ABORTED);
633 case WRITE_COMPLETED_WITH_ERROR:
634 drbd_report_io_error(device, req);
635 __drbd_chk_io_error(device, DRBD_WRITE_ERROR);
636 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
639 case READ_COMPLETED_WITH_ERROR:
640 drbd_set_out_of_sync(device, req->i.sector, req->i.size);
641 drbd_report_io_error(device, req);
642 __drbd_chk_io_error(device, DRBD_READ_ERROR);
644 case READ_AHEAD_COMPLETED_WITH_ERROR:
645 /* it is legal to fail READA, no __drbd_chk_io_error in that case. */
646 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
649 case DISCARD_COMPLETED_NOTSUPP:
650 case DISCARD_COMPLETED_WITH_ERROR:
651 /* I'd rather not detach from local disk just because it
652 * failed a REQ_DISCARD. */
653 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
656 case QUEUE_FOR_NET_READ:
657 /* READ or READA, and
659 * or target area marked as invalid,
660 * or just got an io-error. */
661 /* from __drbd_make_request
662 * or from bio_endio during read io-error recovery */
664 /* So we can verify the handle in the answer packet.
665 * Corresponding drbd_remove_request_interval is in
666 * drbd_req_complete() */
667 D_ASSERT(device, drbd_interval_empty(&req->i));
668 drbd_insert_interval(&device->read_requests, &req->i);
670 set_bit(UNPLUG_REMOTE, &device->flags);
672 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
673 D_ASSERT(device, (req->rq_state & RQ_LOCAL_MASK) == 0);
674 mod_rq_state(req, m, 0, RQ_NET_QUEUED);
675 req->w.cb = w_send_read_req;
676 drbd_queue_work(&connection->sender_work,
680 case QUEUE_FOR_NET_WRITE:
681 /* assert something? */
682 /* from __drbd_make_request only */
684 /* Corresponding drbd_remove_request_interval is in
685 * drbd_req_complete() */
686 D_ASSERT(device, drbd_interval_empty(&req->i));
687 drbd_insert_interval(&device->write_requests, &req->i);
690 * In case the req ended up on the transfer log before being
691 * queued on the worker, it could lead to this request being
692 * missed during cleanup after connection loss.
693 * So we have to do both operations here,
694 * within the same lock that protects the transfer log.
696 * _req_add_to_epoch(req); this has to be after the
697 * _maybe_start_new_epoch(req); which happened in
698 * __drbd_make_request, because we now may set the bit
699 * again ourselves to close the current epoch.
701 * Add req to the (now) current epoch (barrier). */
703 /* otherwise we may lose an unplug, which may cause some remote
704 * io-scheduler timeout to expire, increasing maximum latency,
705 * hurting performance. */
706 set_bit(UNPLUG_REMOTE, &device->flags);
708 /* queue work item to send data */
709 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
710 mod_rq_state(req, m, 0, RQ_NET_QUEUED|RQ_EXP_BARR_ACK);
711 req->w.cb = w_send_dblock;
712 drbd_queue_work(&connection->sender_work,
715 /* close the epoch, in case it outgrew the limit */
717 nc = rcu_dereference(connection->net_conf);
718 p = nc->max_epoch_size;
720 if (connection->current_tle_writes >= p)
721 start_new_tl_epoch(connection);
725 case QUEUE_FOR_SEND_OOS:
726 mod_rq_state(req, m, 0, RQ_NET_QUEUED);
727 req->w.cb = w_send_out_of_sync;
728 drbd_queue_work(&connection->sender_work,
732 case READ_RETRY_REMOTE_CANCELED:
735 /* real cleanup will be done from tl_clear. just update flags
736 * so it is no longer marked as on the worker queue */
737 mod_rq_state(req, m, RQ_NET_QUEUED, 0);
740 case HANDED_OVER_TO_NETWORK:
741 /* assert something? */
742 if (is_pending_write_protocol_A(req))
743 /* this is what is dangerous about protocol A:
744 * pretend it was successfully written on the peer. */
745 mod_rq_state(req, m, RQ_NET_QUEUED|RQ_NET_PENDING,
746 RQ_NET_SENT|RQ_NET_OK);
748 mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_SENT);
749 /* It is still not yet RQ_NET_DONE until the
750 * corresponding epoch barrier got acked as well,
751 * so we know what to dirty on connection loss. */
754 case OOS_HANDED_TO_NETWORK:
755 /* Was not set PENDING, no longer QUEUED, so is now DONE
756 * as far as this connection is concerned. */
757 mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_DONE);
760 case CONNECTION_LOST_WHILE_PENDING:
761 /* transfer log cleanup after connection loss */
763 RQ_NET_OK|RQ_NET_PENDING|RQ_COMPLETION_SUSP,
767 case CONFLICT_RESOLVED:
768 /* for superseded conflicting writes of multiple primaries,
769 * there is no need to keep anything in the tl, potential
770 * node crashes are covered by the activity log.
772 * If this request had been marked as RQ_POSTPONED before,
773 * it will actually not be completed, but "restarted",
774 * resubmitted from the retry worker context. */
775 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
776 D_ASSERT(device, req->rq_state & RQ_EXP_WRITE_ACK);
777 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_DONE|RQ_NET_OK);
780 case WRITE_ACKED_BY_PEER_AND_SIS:
781 req->rq_state |= RQ_NET_SIS;
782 case WRITE_ACKED_BY_PEER:
783 /* Normal operation protocol C: successfully written on peer.
784 * During resync, even in protocol != C,
785 * we requested an explicit write ack anyways.
786 * Which means we cannot even assert anything here.
787 * Nothing more to do here.
788 * We want to keep the tl in place for all protocols, to cater
789 * for volatile write-back caches on lower level devices. */
791 case RECV_ACKED_BY_PEER:
792 D_ASSERT(device, req->rq_state & RQ_EXP_RECEIVE_ACK);
793 /* protocol B; pretends to be successfully written on peer.
794 * see also notes above in HANDED_OVER_TO_NETWORK about
797 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK);
801 D_ASSERT(device, req->rq_state & RQ_EXP_WRITE_ACK);
802 /* If this node has already detected the write conflict, the
803 * worker will be waiting on misc_wait. Wake it up once this
804 * request has completed locally.
806 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
807 req->rq_state |= RQ_POSTPONED;
809 wake_up(&device->misc_wait);
810 /* Do not clear RQ_NET_PENDING. This request will make further
811 * progress via restart_conflicting_writes() or
812 * fail_postponed_requests(). Hopefully. */
816 mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING, 0);
819 case FAIL_FROZEN_DISK_IO:
820 if (!(req->rq_state & RQ_LOCAL_COMPLETED))
822 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0);
825 case RESTART_FROZEN_DISK_IO:
826 if (!(req->rq_state & RQ_LOCAL_COMPLETED))
830 RQ_COMPLETION_SUSP|RQ_LOCAL_COMPLETED,
834 if (bio_data_dir(req->master_bio) == WRITE)
837 get_ldev(device); /* always succeeds in this call path */
838 req->w.cb = w_restart_disk_io;
839 drbd_queue_work(&connection->sender_work,
844 /* Simply complete (local only) READs. */
845 if (!(req->rq_state & RQ_WRITE) && !req->w.cb) {
846 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0);
850 /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK
851 before the connection loss (B&C only); only P_BARRIER_ACK
852 (or the local completion?) was missing when we suspended.
853 Throwing them out of the TL here by pretending we got a BARRIER_ACK.
854 During connection handshake, we ensure that the peer was not rebooted. */
855 if (!(req->rq_state & RQ_NET_OK)) {
856 /* FIXME could this possibly be a req->dw.cb == w_send_out_of_sync?
857 * in that case we must not set RQ_NET_PENDING. */
859 mod_rq_state(req, m, RQ_COMPLETION_SUSP, RQ_NET_QUEUED|RQ_NET_PENDING);
861 /* w.cb expected to be w_send_dblock, or w_send_read_req */
862 drbd_queue_work(&connection->sender_work,
864 rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ;
865 } /* else: FIXME can this happen? */
868 /* else, fall through to BARRIER_ACKED */
871 /* barrier ack for READ requests does not make sense */
872 if (!(req->rq_state & RQ_WRITE))
875 if (req->rq_state & RQ_NET_PENDING) {
876 /* barrier came in before all requests were acked.
877 * this is bad, because if the connection is lost now,
878 * we won't be able to clean them up... */
879 drbd_err(device, "FIXME (BARRIER_ACKED but pending)\n");
881 /* Allowed to complete requests, even while suspended.
882 * As this is called for all requests within a matching epoch,
883 * we need to filter, and only set RQ_NET_DONE for those that
884 * have actually been on the wire. */
885 mod_rq_state(req, m, RQ_COMPLETION_SUSP,
886 (req->rq_state & RQ_NET_MASK) ? RQ_NET_DONE : 0);
890 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
891 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK|RQ_NET_DONE);
894 case QUEUE_AS_DRBD_BARRIER:
895 start_new_tl_epoch(connection);
896 mod_rq_state(req, m, 0, RQ_NET_OK|RQ_NET_DONE);
903 /* we may do a local read if:
904 * - we are consistent (of course),
905 * - or we are generally inconsistent,
906 * BUT we are still/already IN SYNC for this area.
907 * since size may be bigger than BM_BLOCK_SIZE,
908 * we may need to check several bits.
910 static bool drbd_may_do_local_read(struct drbd_device *device, sector_t sector, int size)
912 unsigned long sbnr, ebnr;
913 sector_t esector, nr_sectors;
915 if (device->state.disk == D_UP_TO_DATE)
917 if (device->state.disk != D_INCONSISTENT)
919 esector = sector + (size >> 9) - 1;
920 nr_sectors = drbd_get_capacity(device->this_bdev);
921 D_ASSERT(device, sector < nr_sectors);
922 D_ASSERT(device, esector < nr_sectors);
924 sbnr = BM_SECT_TO_BIT(sector);
925 ebnr = BM_SECT_TO_BIT(esector);
927 return drbd_bm_count_bits(device, sbnr, ebnr) == 0;
930 static bool remote_due_to_read_balancing(struct drbd_device *device, sector_t sector,
931 enum drbd_read_balancing rbm)
933 struct backing_dev_info *bdi;
937 case RB_CONGESTED_REMOTE:
938 bdi = &device->ldev->backing_bdev->bd_disk->queue->backing_dev_info;
939 return bdi_read_congested(bdi);
940 case RB_LEAST_PENDING:
941 return atomic_read(&device->local_cnt) >
942 atomic_read(&device->ap_pending_cnt) + atomic_read(&device->rs_pending_cnt);
943 case RB_32K_STRIPING: /* stripe_shift = 15 */
944 case RB_64K_STRIPING:
945 case RB_128K_STRIPING:
946 case RB_256K_STRIPING:
947 case RB_512K_STRIPING:
948 case RB_1M_STRIPING: /* stripe_shift = 20 */
949 stripe_shift = (rbm - RB_32K_STRIPING + 15);
950 return (sector >> (stripe_shift - 9)) & 1;
952 return test_and_change_bit(READ_BALANCE_RR, &device->flags);
953 case RB_PREFER_REMOTE:
955 case RB_PREFER_LOCAL:
962 * complete_conflicting_writes - wait for any conflicting write requests
964 * The write_requests tree contains all active write requests which we
965 * currently know about. Wait for any requests to complete which conflict with
968 * Only way out: remove the conflicting intervals from the tree.
970 static void complete_conflicting_writes(struct drbd_request *req)
973 struct drbd_device *device = req->device;
974 struct drbd_interval *i;
975 sector_t sector = req->i.sector;
976 int size = req->i.size;
978 i = drbd_find_overlap(&device->write_requests, sector, size);
983 prepare_to_wait(&device->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
984 i = drbd_find_overlap(&device->write_requests, sector, size);
987 /* Indicate to wake up device->misc_wait on progress. */
989 spin_unlock_irq(&device->resource->req_lock);
991 spin_lock_irq(&device->resource->req_lock);
993 finish_wait(&device->misc_wait, &wait);
996 /* called within req_lock and rcu_read_lock() */
997 static void maybe_pull_ahead(struct drbd_device *device)
999 struct drbd_connection *connection = first_peer_device(device)->connection;
1000 struct net_conf *nc;
1001 bool congested = false;
1002 enum drbd_on_congestion on_congestion;
1005 nc = rcu_dereference(connection->net_conf);
1006 on_congestion = nc ? nc->on_congestion : OC_BLOCK;
1008 if (on_congestion == OC_BLOCK ||
1009 connection->agreed_pro_version < 96)
1012 if (on_congestion == OC_PULL_AHEAD && device->state.conn == C_AHEAD)
1013 return; /* nothing to do ... */
1015 /* If I don't even have good local storage, we can not reasonably try
1016 * to pull ahead of the peer. We also need the local reference to make
1017 * sure device->act_log is there.
1019 if (!get_ldev_if_state(device, D_UP_TO_DATE))
1022 if (nc->cong_fill &&
1023 atomic_read(&device->ap_in_flight) >= nc->cong_fill) {
1024 drbd_info(device, "Congestion-fill threshold reached\n");
1028 if (device->act_log->used >= nc->cong_extents) {
1029 drbd_info(device, "Congestion-extents threshold reached\n");
1034 /* start a new epoch for non-mirrored writes */
1035 start_new_tl_epoch(first_peer_device(device)->connection);
1037 if (on_congestion == OC_PULL_AHEAD)
1038 _drbd_set_state(_NS(device, conn, C_AHEAD), 0, NULL);
1039 else /*nc->on_congestion == OC_DISCONNECT */
1040 _drbd_set_state(_NS(device, conn, C_DISCONNECTING), 0, NULL);
1045 /* If this returns false, and req->private_bio is still set,
1046 * this should be submitted locally.
1048 * If it returns false, but req->private_bio is not set,
1049 * we do not have access to good data :(
1051 * Otherwise, this destroys req->private_bio, if any,
1054 static bool do_remote_read(struct drbd_request *req)
1056 struct drbd_device *device = req->device;
1057 enum drbd_read_balancing rbm;
1059 if (req->private_bio) {
1060 if (!drbd_may_do_local_read(device,
1061 req->i.sector, req->i.size)) {
1062 bio_put(req->private_bio);
1063 req->private_bio = NULL;
1068 if (device->state.pdsk != D_UP_TO_DATE)
1071 if (req->private_bio == NULL)
1074 /* TODO: improve read balancing decisions, take into account drbd
1075 * protocol, pending requests etc. */
1078 rbm = rcu_dereference(device->ldev->disk_conf)->read_balancing;
1081 if (rbm == RB_PREFER_LOCAL && req->private_bio)
1082 return false; /* submit locally */
1084 if (remote_due_to_read_balancing(device, req->i.sector, rbm)) {
1085 if (req->private_bio) {
1086 bio_put(req->private_bio);
1087 req->private_bio = NULL;
1096 /* returns number of connections (== 1, for drbd 8.4)
1097 * expected to actually write this data,
1098 * which does NOT include those that we are L_AHEAD for. */
1099 static int drbd_process_write_request(struct drbd_request *req)
1101 struct drbd_device *device = req->device;
1102 int remote, send_oos;
1104 remote = drbd_should_do_remote(device->state);
1105 send_oos = drbd_should_send_out_of_sync(device->state);
1107 /* Need to replicate writes. Unless it is an empty flush,
1108 * which is better mapped to a DRBD P_BARRIER packet,
1109 * also for drbd wire protocol compatibility reasons.
1110 * If this was a flush, just start a new epoch.
1111 * Unless the current epoch was empty anyways, or we are not currently
1112 * replicating, in which case there is no point. */
1113 if (unlikely(req->i.size == 0)) {
1114 /* The only size==0 bios we expect are empty flushes. */
1115 D_ASSERT(device, req->master_bio->bi_rw & REQ_FLUSH);
1117 _req_mod(req, QUEUE_AS_DRBD_BARRIER);
1121 if (!remote && !send_oos)
1124 D_ASSERT(device, !(remote && send_oos));
1127 _req_mod(req, TO_BE_SENT);
1128 _req_mod(req, QUEUE_FOR_NET_WRITE);
1129 } else if (drbd_set_out_of_sync(device, req->i.sector, req->i.size))
1130 _req_mod(req, QUEUE_FOR_SEND_OOS);
1136 drbd_submit_req_private_bio(struct drbd_request *req)
1138 struct drbd_device *device = req->device;
1139 struct bio *bio = req->private_bio;
1140 const int rw = bio_rw(bio);
1142 bio->bi_bdev = device->ldev->backing_bdev;
1144 /* State may have changed since we grabbed our reference on the
1145 * ->ldev member. Double check, and short-circuit to endio.
1146 * In case the last activity log transaction failed to get on
1147 * stable storage, and this is a WRITE, we may not even submit
1149 if (get_ldev(device)) {
1150 req->pre_submit_jif = jiffies;
1151 if (drbd_insert_fault(device,
1152 rw == WRITE ? DRBD_FAULT_DT_WR
1153 : rw == READ ? DRBD_FAULT_DT_RD
1154 : DRBD_FAULT_DT_RA))
1155 bio_endio(bio, -EIO);
1157 generic_make_request(bio);
1160 bio_endio(bio, -EIO);
1163 static void drbd_queue_write(struct drbd_device *device, struct drbd_request *req)
1165 spin_lock_irq(&device->resource->req_lock);
1166 list_add_tail(&req->tl_requests, &device->submit.writes);
1167 list_add_tail(&req->req_pending_master_completion,
1168 &device->pending_master_completion[1 /* WRITE */]);
1169 spin_unlock_irq(&device->resource->req_lock);
1170 queue_work(device->submit.wq, &device->submit.worker);
1171 /* do_submit() may sleep internally on al_wait, too */
1172 wake_up(&device->al_wait);
1175 /* returns the new drbd_request pointer, if the caller is expected to
1176 * drbd_send_and_submit() it (to save latency), or NULL if we queued the
1177 * request on the submitter thread.
1178 * Returns ERR_PTR(-ENOMEM) if we cannot allocate a drbd_request.
1180 static struct drbd_request *
1181 drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long start_jif)
1183 const int rw = bio_data_dir(bio);
1184 struct drbd_request *req;
1186 /* allocate outside of all locks; */
1187 req = drbd_req_new(device, bio);
1190 /* only pass the error to the upper layers.
1191 * if user cannot handle io errors, that's not our business. */
1192 drbd_err(device, "could not kmalloc() req\n");
1193 bio_endio(bio, -ENOMEM);
1194 return ERR_PTR(-ENOMEM);
1196 req->start_jif = start_jif;
1198 if (!get_ldev(device)) {
1199 bio_put(req->private_bio);
1200 req->private_bio = NULL;
1203 /* Update disk stats */
1204 _drbd_start_io_acct(device, req);
1206 if (rw == WRITE && req->private_bio && req->i.size
1207 && !test_bit(AL_SUSPENDED, &device->flags)) {
1208 if (!drbd_al_begin_io_fastpath(device, &req->i)) {
1209 atomic_inc(&device->ap_actlog_cnt);
1210 drbd_queue_write(device, req);
1213 req->rq_state |= RQ_IN_ACT_LOG;
1214 req->in_actlog_jif = jiffies;
1220 static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req)
1222 struct drbd_resource *resource = device->resource;
1223 const int rw = bio_rw(req->master_bio);
1224 struct bio_and_error m = { NULL, };
1225 bool no_remote = false;
1226 bool submit_private_bio = false;
1228 spin_lock_irq(&resource->req_lock);
1230 /* This may temporarily give up the req_lock,
1231 * but will re-aquire it before it returns here.
1232 * Needs to be before the check on drbd_suspended() */
1233 complete_conflicting_writes(req);
1234 /* no more giving up req_lock from now on! */
1236 /* check for congestion, and potentially stop sending
1237 * full data updates, but start sending "dirty bits" only. */
1238 maybe_pull_ahead(device);
1242 if (drbd_suspended(device)) {
1243 /* push back and retry: */
1244 req->rq_state |= RQ_POSTPONED;
1245 if (req->private_bio) {
1246 bio_put(req->private_bio);
1247 req->private_bio = NULL;
1253 /* We fail READ/READA early, if we can not serve it.
1254 * We must do this before req is registered on any lists.
1255 * Otherwise, drbd_req_complete() will queue failed READ for retry. */
1257 if (!do_remote_read(req) && !req->private_bio)
1261 /* which transfer log epoch does this belong to? */
1262 req->epoch = atomic_read(&first_peer_device(device)->connection->current_tle_nr);
1264 /* no point in adding empty flushes to the transfer log,
1265 * they are mapped to drbd barriers already. */
1266 if (likely(req->i.size!=0)) {
1268 first_peer_device(device)->connection->current_tle_writes++;
1270 list_add_tail(&req->tl_requests, &first_peer_device(device)->connection->transfer_log);
1274 if (!drbd_process_write_request(req))
1277 /* We either have a private_bio, or we can read from remote.
1278 * Otherwise we had done the goto nodata above. */
1279 if (req->private_bio == NULL) {
1280 _req_mod(req, TO_BE_SENT);
1281 _req_mod(req, QUEUE_FOR_NET_READ);
1286 /* If it took the fast path in drbd_request_prepare, add it here.
1287 * The slow path has added it already. */
1288 if (list_empty(&req->req_pending_master_completion))
1289 list_add_tail(&req->req_pending_master_completion,
1290 &device->pending_master_completion[rw == WRITE]);
1291 if (req->private_bio) {
1292 /* needs to be marked within the same spinlock */
1293 list_add_tail(&req->req_pending_local,
1294 &device->pending_completion[rw == WRITE]);
1295 _req_mod(req, TO_BE_SUBMITTED);
1296 /* but we need to give up the spinlock to submit */
1297 submit_private_bio = true;
1298 } else if (no_remote) {
1300 if (__ratelimit(&drbd_ratelimit_state))
1301 drbd_err(device, "IO ERROR: neither local nor remote data, sector %llu+%u\n",
1302 (unsigned long long)req->i.sector, req->i.size >> 9);
1303 /* A write may have been queued for send_oos, however.
1304 * So we can not simply free it, we must go through drbd_req_put_completion_ref() */
1308 if (drbd_req_put_completion_ref(req, &m, 1))
1309 kref_put(&req->kref, drbd_req_destroy);
1310 spin_unlock_irq(&resource->req_lock);
1312 /* Even though above is a kref_put(), this is safe.
1313 * As long as we still need to submit our private bio,
1314 * we hold a completion ref, and the request cannot disappear.
1315 * If however this request did not even have a private bio to submit
1316 * (e.g. remote read), req may already be invalid now.
1317 * That's why we cannot check on req->private_bio. */
1318 if (submit_private_bio)
1319 drbd_submit_req_private_bio(req);
1321 complete_master_bio(device, &m);
1324 void __drbd_make_request(struct drbd_device *device, struct bio *bio, unsigned long start_jif)
1326 struct drbd_request *req = drbd_request_prepare(device, bio, start_jif);
1327 if (IS_ERR_OR_NULL(req))
1329 drbd_send_and_submit(device, req);
1332 static void submit_fast_path(struct drbd_device *device, struct list_head *incoming)
1334 struct drbd_request *req, *tmp;
1335 list_for_each_entry_safe(req, tmp, incoming, tl_requests) {
1336 const int rw = bio_data_dir(req->master_bio);
1338 if (rw == WRITE /* rw != WRITE should not even end up here! */
1339 && req->private_bio && req->i.size
1340 && !test_bit(AL_SUSPENDED, &device->flags)) {
1341 if (!drbd_al_begin_io_fastpath(device, &req->i))
1344 req->rq_state |= RQ_IN_ACT_LOG;
1345 req->in_actlog_jif = jiffies;
1346 atomic_dec(&device->ap_actlog_cnt);
1349 list_del_init(&req->tl_requests);
1350 drbd_send_and_submit(device, req);
1354 static bool prepare_al_transaction_nonblock(struct drbd_device *device,
1355 struct list_head *incoming,
1356 struct list_head *pending,
1357 struct list_head *later)
1359 struct drbd_request *req, *tmp;
1363 spin_lock_irq(&device->al_lock);
1364 list_for_each_entry_safe(req, tmp, incoming, tl_requests) {
1365 err = drbd_al_begin_io_nonblock(device, &req->i);
1366 if (err == -ENOBUFS)
1371 list_move_tail(&req->tl_requests, later);
1373 list_move_tail(&req->tl_requests, pending);
1375 spin_unlock_irq(&device->al_lock);
1377 wake_up(&device->al_wait);
1378 return !list_empty(pending);
1381 void send_and_submit_pending(struct drbd_device *device, struct list_head *pending)
1383 struct drbd_request *req, *tmp;
1385 list_for_each_entry_safe(req, tmp, pending, tl_requests) {
1386 req->rq_state |= RQ_IN_ACT_LOG;
1387 req->in_actlog_jif = jiffies;
1388 atomic_dec(&device->ap_actlog_cnt);
1389 list_del_init(&req->tl_requests);
1390 drbd_send_and_submit(device, req);
1394 void do_submit(struct work_struct *ws)
1396 struct drbd_device *device = container_of(ws, struct drbd_device, submit.worker);
1397 LIST_HEAD(incoming); /* from drbd_make_request() */
1398 LIST_HEAD(pending); /* to be submitted after next AL-transaction commit */
1399 LIST_HEAD(busy); /* blocked by resync requests */
1401 /* grab new incoming requests */
1402 spin_lock_irq(&device->resource->req_lock);
1403 list_splice_tail_init(&device->submit.writes, &incoming);
1404 spin_unlock_irq(&device->resource->req_lock);
1409 /* move used-to-be-busy back to front of incoming */
1410 list_splice_init(&busy, &incoming);
1411 submit_fast_path(device, &incoming);
1412 if (list_empty(&incoming))
1416 prepare_to_wait(&device->al_wait, &wait, TASK_UNINTERRUPTIBLE);
1418 list_splice_init(&busy, &incoming);
1419 prepare_al_transaction_nonblock(device, &incoming, &pending, &busy);
1420 if (!list_empty(&pending))
1425 /* If all currently "hot" activity log extents are kept busy by
1426 * incoming requests, we still must not totally starve new
1427 * requests to "cold" extents.
1428 * Something left on &incoming means there had not been
1429 * enough update slots available, and the activity log
1430 * has been marked as "starving".
1432 * Try again now, without looking for new requests,
1433 * effectively blocking all new requests until we made
1434 * at least _some_ progress with what we currently have.
1436 if (!list_empty(&incoming))
1439 /* Nothing moved to pending, but nothing left
1440 * on incoming: all moved to busy!
1441 * Grab new and iterate. */
1442 spin_lock_irq(&device->resource->req_lock);
1443 list_splice_tail_init(&device->submit.writes, &incoming);
1444 spin_unlock_irq(&device->resource->req_lock);
1446 finish_wait(&device->al_wait, &wait);
1448 /* If the transaction was full, before all incoming requests
1449 * had been processed, skip ahead to commit, and iterate
1450 * without splicing in more incoming requests from upper layers.
1452 * Else, if all incoming have been processed,
1453 * they have become either "pending" (to be submitted after
1454 * next transaction commit) or "busy" (blocked by resync).
1456 * Maybe more was queued, while we prepared the transaction?
1457 * Try to stuff those into this transaction as well.
1458 * Be strictly non-blocking here,
1459 * we already have something to commit.
1461 * Commit if we don't make any more progres.
1464 while (list_empty(&incoming)) {
1465 LIST_HEAD(more_pending);
1466 LIST_HEAD(more_incoming);
1469 /* It is ok to look outside the lock,
1470 * it's only an optimization anyways */
1471 if (list_empty(&device->submit.writes))
1474 spin_lock_irq(&device->resource->req_lock);
1475 list_splice_tail_init(&device->submit.writes, &more_incoming);
1476 spin_unlock_irq(&device->resource->req_lock);
1478 if (list_empty(&more_incoming))
1481 made_progress = prepare_al_transaction_nonblock(device, &more_incoming, &more_pending, &busy);
1483 list_splice_tail_init(&more_pending, &pending);
1484 list_splice_tail_init(&more_incoming, &incoming);
1489 drbd_al_begin_io_commit(device);
1490 send_and_submit_pending(device, &pending);
1494 void drbd_make_request(struct request_queue *q, struct bio *bio)
1496 struct drbd_device *device = (struct drbd_device *) q->queuedata;
1497 unsigned long start_jif;
1499 start_jif = jiffies;
1502 * what we "blindly" assume:
1504 D_ASSERT(device, IS_ALIGNED(bio->bi_iter.bi_size, 512));
1507 __drbd_make_request(device, bio, start_jif);
1510 /* This is called by bio_add_page().
1512 * q->max_hw_sectors and other global limits are already enforced there.
1514 * We need to call down to our lower level device,
1515 * in case it has special restrictions.
1517 * We also may need to enforce configured max-bio-bvecs limits.
1519 * As long as the BIO is empty we have to allow at least one bvec,
1520 * regardless of size and offset, so no need to ask lower levels.
1522 int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)
1524 struct drbd_device *device = (struct drbd_device *) q->queuedata;
1525 unsigned int bio_size = bvm->bi_size;
1526 int limit = DRBD_MAX_BIO_SIZE;
1529 if (bio_size && get_ldev(device)) {
1530 unsigned int max_hw_sectors = queue_max_hw_sectors(q);
1531 struct request_queue * const b =
1532 device->ldev->backing_bdev->bd_disk->queue;
1533 if (b->merge_bvec_fn) {
1534 bvm->bi_bdev = device->ldev->backing_bdev;
1535 backing_limit = b->merge_bvec_fn(b, bvm, bvec);
1536 limit = min(limit, backing_limit);
1539 if ((limit >> 9) > max_hw_sectors)
1540 limit = max_hw_sectors << 9;
1545 void request_timer_fn(unsigned long data)
1547 struct drbd_device *device = (struct drbd_device *) data;
1548 struct drbd_connection *connection = first_peer_device(device)->connection;
1549 struct drbd_request *req_read, *req_write, *req_peer; /* oldest request */
1550 struct net_conf *nc;
1551 unsigned long oldest_submit_jif;
1552 unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */
1556 nc = rcu_dereference(connection->net_conf);
1557 if (nc && device->state.conn >= C_WF_REPORT_PARAMS)
1558 ent = nc->timeout * HZ/10 * nc->ko_count;
1560 if (get_ldev(device)) { /* implicit state.disk >= D_INCONSISTENT */
1561 dt = rcu_dereference(device->ldev->disk_conf)->disk_timeout * HZ / 10;
1566 et = min_not_zero(dt, ent);
1569 return; /* Recurring timer stopped */
1574 spin_lock_irq(&device->resource->req_lock);
1575 req_read = list_first_entry_or_null(&device->pending_completion[0], struct drbd_request, req_pending_local);
1576 req_write = list_first_entry_or_null(&device->pending_completion[1], struct drbd_request, req_pending_local);
1577 req_peer = connection->req_not_net_done;
1578 /* maybe the oldest request waiting for the peer is in fact still
1579 * blocking in tcp sendmsg */
1580 if (!req_peer && connection->req_next && connection->req_next->pre_send_jif)
1581 req_peer = connection->req_next;
1583 /* evaluate the oldest peer request only in one timer! */
1584 if (req_peer && req_peer->device != device)
1587 /* do we have something to evaluate? */
1588 if (req_peer == NULL && req_write == NULL && req_read == NULL)
1592 (req_write && req_read)
1593 ? ( time_before(req_write->pre_submit_jif, req_read->pre_submit_jif)
1594 ? req_write->pre_submit_jif : req_read->pre_submit_jif )
1595 : req_write ? req_write->pre_submit_jif
1596 : req_read ? req_read->pre_submit_jif : now;
1598 /* The request is considered timed out, if
1599 * - we have some effective timeout from the configuration,
1600 * with above state restrictions applied,
1601 * - the oldest request is waiting for a response from the network
1602 * resp. the local disk,
1603 * - the oldest request is in fact older than the effective timeout,
1604 * - the connection was established (resp. disk was attached)
1605 * for longer than the timeout already.
1606 * Note that for 32bit jiffies and very stable connections/disks,
1607 * we may have a wrap around, which is catched by
1608 * !time_in_range(now, last_..._jif, last_..._jif + timeout).
1610 * Side effect: once per 32bit wrap-around interval, which means every
1611 * ~198 days with 250 HZ, we have a window where the timeout would need
1612 * to expire twice (worst case) to become effective. Good enough.
1614 if (ent && req_peer &&
1615 time_after(now, req_peer->pre_send_jif + ent) &&
1616 !time_in_range(now, connection->last_reconnect_jif, connection->last_reconnect_jif + ent)) {
1617 drbd_warn(device, "Remote failed to finish a request within ko-count * timeout\n");
1618 _conn_request_state(connection, NS(conn, C_TIMEOUT), CS_VERBOSE | CS_HARD);
1620 if (dt && oldest_submit_jif != now &&
1621 time_after(now, oldest_submit_jif + dt) &&
1622 !time_in_range(now, device->last_reattach_jif, device->last_reattach_jif + dt)) {
1623 drbd_warn(device, "Local backing device failed to meet the disk-timeout\n");
1624 __drbd_chk_io_error(device, DRBD_FORCE_DETACH);
1627 /* Reschedule timer for the nearest not already expired timeout.
1628 * Fallback to now + min(effective network timeout, disk timeout). */
1629 ent = (ent && req_peer && time_before(now, req_peer->pre_send_jif + ent))
1630 ? req_peer->pre_send_jif + ent : now + et;
1631 dt = (dt && oldest_submit_jif != now && time_before(now, oldest_submit_jif + dt))
1632 ? oldest_submit_jif + dt : now + et;
1633 nt = time_before(ent, dt) ? ent : dt;
1635 spin_unlock_irq(&device->resource->req_lock);
1636 mod_timer(&device->request_timer, nt);