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Philipp Reisnerb411b362009-09-25 16:07:19 -07001/*
2 drbd_req.c
3
4 This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
5
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>.
9
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)
13 any later version.
14
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.
19
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.
23
24 */
25
Philipp Reisnerb411b362009-09-25 16:07:19 -070026#include <linux/module.h>
27
28#include <linux/slab.h>
29#include <linux/drbd.h>
30#include "drbd_int.h"
Philipp Reisnerb411b362009-09-25 16:07:19 -070031#include "drbd_req.h"
32
33
34/* Update disk stats at start of I/O request */
35static void _drbd_start_io_acct(struct drbd_conf *mdev, struct drbd_request *req, struct bio *bio)
36{
37 const int rw = bio_data_dir(bio);
38 int cpu;
39 cpu = part_stat_lock();
40 part_stat_inc(cpu, &mdev->vdisk->part0, ios[rw]);
41 part_stat_add(cpu, &mdev->vdisk->part0, sectors[rw], bio_sectors(bio));
Philipp Reisner753c8912009-11-18 15:52:51 +010042 part_inc_in_flight(&mdev->vdisk->part0, rw);
Philipp Reisnerb411b362009-09-25 16:07:19 -070043 part_stat_unlock();
Philipp Reisnerb411b362009-09-25 16:07:19 -070044}
45
46/* Update disk stats when completing request upwards */
47static void _drbd_end_io_acct(struct drbd_conf *mdev, struct drbd_request *req)
48{
49 int rw = bio_data_dir(req->master_bio);
50 unsigned long duration = jiffies - req->start_time;
51 int cpu;
52 cpu = part_stat_lock();
53 part_stat_add(cpu, &mdev->vdisk->part0, ticks[rw], duration);
54 part_round_stats(cpu, &mdev->vdisk->part0);
Philipp Reisner753c8912009-11-18 15:52:51 +010055 part_dec_in_flight(&mdev->vdisk->part0, rw);
Philipp Reisnerb411b362009-09-25 16:07:19 -070056 part_stat_unlock();
Philipp Reisnerb411b362009-09-25 16:07:19 -070057}
58
59static void _req_is_done(struct drbd_conf *mdev, struct drbd_request *req, const int rw)
60{
61 const unsigned long s = req->rq_state;
Philipp Reisner288f4222010-05-27 15:07:43 +020062
63 /* remove it from the transfer log.
64 * well, only if it had been there in the first
65 * place... if it had not (local only or conflicting
66 * and never sent), it should still be "empty" as
67 * initialized in drbd_req_new(), so we can list_del() it
68 * here unconditionally */
69 list_del(&req->tl_requests);
70
Philipp Reisnerb411b362009-09-25 16:07:19 -070071 /* if it was a write, we may have to set the corresponding
72 * bit(s) out-of-sync first. If it had a local part, we need to
73 * release the reference to the activity log. */
74 if (rw == WRITE) {
Philipp Reisnerb411b362009-09-25 16:07:19 -070075 /* Set out-of-sync unless both OK flags are set
76 * (local only or remote failed).
77 * Other places where we set out-of-sync:
78 * READ with local io-error */
79 if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK))
80 drbd_set_out_of_sync(mdev, req->sector, req->size);
81
82 if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS))
83 drbd_set_in_sync(mdev, req->sector, req->size);
84
85 /* one might be tempted to move the drbd_al_complete_io
86 * to the local io completion callback drbd_endio_pri.
87 * but, if this was a mirror write, we may only
88 * drbd_al_complete_io after this is RQ_NET_DONE,
89 * otherwise the extent could be dropped from the al
90 * before it has actually been written on the peer.
91 * if we crash before our peer knows about the request,
92 * but after the extent has been dropped from the al,
93 * we would forget to resync the corresponding extent.
94 */
95 if (s & RQ_LOCAL_MASK) {
96 if (get_ldev_if_state(mdev, D_FAILED)) {
Philipp Reisner07782862010-08-31 12:00:50 +020097 if (s & RQ_IN_ACT_LOG)
98 drbd_al_complete_io(mdev, req->sector);
Philipp Reisnerb411b362009-09-25 16:07:19 -070099 put_ldev(mdev);
100 } else if (__ratelimit(&drbd_ratelimit_state)) {
101 dev_warn(DEV, "Should have called drbd_al_complete_io(, %llu), "
102 "but my Disk seems to have failed :(\n",
103 (unsigned long long) req->sector);
104 }
105 }
106 }
107
Philipp Reisner32fa7e92010-05-26 17:13:18 +0200108 drbd_req_free(req);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700109}
110
111static void queue_barrier(struct drbd_conf *mdev)
112{
113 struct drbd_tl_epoch *b;
114
115 /* We are within the req_lock. Once we queued the barrier for sending,
116 * we set the CREATE_BARRIER bit. It is cleared as soon as a new
117 * barrier/epoch object is added. This is the only place this bit is
118 * set. It indicates that the barrier for this epoch is already queued,
119 * and no new epoch has been created yet. */
120 if (test_bit(CREATE_BARRIER, &mdev->flags))
121 return;
122
123 b = mdev->newest_tle;
124 b->w.cb = w_send_barrier;
125 /* inc_ap_pending done here, so we won't
126 * get imbalanced on connection loss.
127 * dec_ap_pending will be done in got_BarrierAck
128 * or (on connection loss) in tl_clear. */
129 inc_ap_pending(mdev);
130 drbd_queue_work(&mdev->data.work, &b->w);
131 set_bit(CREATE_BARRIER, &mdev->flags);
132}
133
134static void _about_to_complete_local_write(struct drbd_conf *mdev,
135 struct drbd_request *req)
136{
137 const unsigned long s = req->rq_state;
138 struct drbd_request *i;
139 struct drbd_epoch_entry *e;
140 struct hlist_node *n;
141 struct hlist_head *slot;
142
143 /* before we can signal completion to the upper layers,
144 * we may need to close the current epoch */
145 if (mdev->state.conn >= C_CONNECTED &&
146 req->epoch == mdev->newest_tle->br_number)
147 queue_barrier(mdev);
148
149 /* we need to do the conflict detection stuff,
150 * if we have the ee_hash (two_primaries) and
151 * this has been on the network */
152 if ((s & RQ_NET_DONE) && mdev->ee_hash != NULL) {
153 const sector_t sector = req->sector;
154 const int size = req->size;
155
156 /* ASSERT:
157 * there must be no conflicting requests, since
158 * they must have been failed on the spot */
159#define OVERLAPS overlaps(sector, size, i->sector, i->size)
160 slot = tl_hash_slot(mdev, sector);
161 hlist_for_each_entry(i, n, slot, colision) {
162 if (OVERLAPS) {
163 dev_alert(DEV, "LOGIC BUG: completed: %p %llus +%u; "
164 "other: %p %llus +%u\n",
165 req, (unsigned long long)sector, size,
166 i, (unsigned long long)i->sector, i->size);
167 }
168 }
169
170 /* maybe "wake" those conflicting epoch entries
171 * that wait for this request to finish.
172 *
173 * currently, there can be only _one_ such ee
174 * (well, or some more, which would be pending
175 * P_DISCARD_ACK not yet sent by the asender...),
176 * since we block the receiver thread upon the
177 * first conflict detection, which will wait on
178 * misc_wait. maybe we want to assert that?
179 *
180 * anyways, if we found one,
181 * we just have to do a wake_up. */
182#undef OVERLAPS
183#define OVERLAPS overlaps(sector, size, e->sector, e->size)
184 slot = ee_hash_slot(mdev, req->sector);
185 hlist_for_each_entry(e, n, slot, colision) {
186 if (OVERLAPS) {
187 wake_up(&mdev->misc_wait);
188 break;
189 }
190 }
191 }
192#undef OVERLAPS
193}
194
195void complete_master_bio(struct drbd_conf *mdev,
196 struct bio_and_error *m)
197{
Philipp Reisnerb411b362009-09-25 16:07:19 -0700198 bio_endio(m->bio, m->error);
199 dec_ap_bio(mdev);
200}
201
202/* Helper for __req_mod().
203 * Set m->bio to the master bio, if it is fit to be completed,
204 * or leave it alone (it is initialized to NULL in __req_mod),
205 * if it has already been completed, or cannot be completed yet.
206 * If m->bio is set, the error status to be returned is placed in m->error.
207 */
208void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
209{
210 const unsigned long s = req->rq_state;
211 struct drbd_conf *mdev = req->mdev;
212 /* only WRITES may end up here without a master bio (on barrier ack) */
213 int rw = req->master_bio ? bio_data_dir(req->master_bio) : WRITE;
214
Philipp Reisnerb411b362009-09-25 16:07:19 -0700215 /* we must not complete the master bio, while it is
216 * still being processed by _drbd_send_zc_bio (drbd_send_dblock)
217 * not yet acknowledged by the peer
218 * not yet completed by the local io subsystem
219 * these flags may get cleared in any order by
220 * the worker,
221 * the receiver,
222 * the bio_endio completion callbacks.
223 */
224 if (s & RQ_NET_QUEUED)
225 return;
226 if (s & RQ_NET_PENDING)
227 return;
228 if (s & RQ_LOCAL_PENDING)
229 return;
230
231 if (req->master_bio) {
232 /* this is data_received (remote read)
233 * or protocol C P_WRITE_ACK
234 * or protocol B P_RECV_ACK
235 * or protocol A "handed_over_to_network" (SendAck)
236 * or canceled or failed,
237 * or killed from the transfer log due to connection loss.
238 */
239
240 /*
241 * figure out whether to report success or failure.
242 *
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.
246 *
247 * what to do about the failures is handled elsewhere.
248 * what we need to do here is just: complete the master_bio.
249 *
250 * local completion error, if any, has been stored as ERR_PTR
251 * in private_bio within drbd_endio_pri.
252 */
253 int ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK);
254 int error = PTR_ERR(req->private_bio);
255
256 /* remove the request from the conflict detection
257 * respective block_id verification hash */
258 if (!hlist_unhashed(&req->colision))
259 hlist_del(&req->colision);
260 else
Philipp Reisner8825f7c2010-10-21 17:21:19 +0200261 D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700262
263 /* for writes we need to do some extra housekeeping */
264 if (rw == WRITE)
265 _about_to_complete_local_write(mdev, req);
266
267 /* Update disk stats */
268 _drbd_end_io_acct(mdev, req);
269
270 m->error = ok ? 0 : (error ?: -EIO);
271 m->bio = req->master_bio;
272 req->master_bio = NULL;
273 }
274
275 if ((s & RQ_NET_MASK) == 0 || (s & RQ_NET_DONE)) {
276 /* this is disconnected (local only) operation,
277 * or protocol C P_WRITE_ACK,
278 * or protocol A or B P_BARRIER_ACK,
279 * or killed from the transfer log due to connection loss. */
280 _req_is_done(mdev, req, rw);
281 }
282 /* else: network part and not DONE yet. that is
283 * protocol A or B, barrier ack still pending... */
284}
285
Philipp Reisnercfa03412010-06-23 17:18:51 +0200286static void _req_may_be_done_not_susp(struct drbd_request *req, struct bio_and_error *m)
287{
288 struct drbd_conf *mdev = req->mdev;
289
Philipp Reisnerfb22c402010-09-08 23:20:21 +0200290 if (!is_susp(mdev->state))
Philipp Reisnercfa03412010-06-23 17:18:51 +0200291 _req_may_be_done(req, m);
292}
293
Philipp Reisnerb411b362009-09-25 16:07:19 -0700294/*
295 * checks whether there was an overlapping request
296 * or ee already registered.
297 *
298 * if so, return 1, in which case this request is completed on the spot,
299 * without ever being submitted or send.
300 *
301 * return 0 if it is ok to submit this request.
302 *
303 * NOTE:
304 * paranoia: assume something above us is broken, and issues different write
305 * requests for the same block simultaneously...
306 *
307 * To ensure these won't be reordered differently on both nodes, resulting in
308 * diverging data sets, we discard the later one(s). Not that this is supposed
309 * to happen, but this is the rationale why we also have to check for
310 * conflicting requests with local origin, and why we have to do so regardless
311 * of whether we allowed multiple primaries.
312 *
313 * BTW, in case we only have one primary, the ee_hash is empty anyways, and the
314 * second hlist_for_each_entry becomes a noop. This is even simpler than to
315 * grab a reference on the net_conf, and check for the two_primaries flag...
316 */
317static int _req_conflicts(struct drbd_request *req)
318{
319 struct drbd_conf *mdev = req->mdev;
320 const sector_t sector = req->sector;
321 const int size = req->size;
322 struct drbd_request *i;
323 struct drbd_epoch_entry *e;
324 struct hlist_node *n;
325 struct hlist_head *slot;
326
327 D_ASSERT(hlist_unhashed(&req->colision));
328
329 if (!get_net_conf(mdev))
330 return 0;
331
332 /* BUG_ON */
333 ERR_IF (mdev->tl_hash_s == 0)
334 goto out_no_conflict;
335 BUG_ON(mdev->tl_hash == NULL);
336
337#define OVERLAPS overlaps(i->sector, i->size, sector, size)
338 slot = tl_hash_slot(mdev, sector);
339 hlist_for_each_entry(i, n, slot, colision) {
340 if (OVERLAPS) {
341 dev_alert(DEV, "%s[%u] Concurrent local write detected! "
342 "[DISCARD L] new: %llus +%u; "
343 "pending: %llus +%u\n",
344 current->comm, current->pid,
345 (unsigned long long)sector, size,
346 (unsigned long long)i->sector, i->size);
347 goto out_conflict;
348 }
349 }
350
351 if (mdev->ee_hash_s) {
352 /* now, check for overlapping requests with remote origin */
353 BUG_ON(mdev->ee_hash == NULL);
354#undef OVERLAPS
355#define OVERLAPS overlaps(e->sector, e->size, sector, size)
356 slot = ee_hash_slot(mdev, sector);
357 hlist_for_each_entry(e, n, slot, colision) {
358 if (OVERLAPS) {
359 dev_alert(DEV, "%s[%u] Concurrent remote write detected!"
360 " [DISCARD L] new: %llus +%u; "
361 "pending: %llus +%u\n",
362 current->comm, current->pid,
363 (unsigned long long)sector, size,
364 (unsigned long long)e->sector, e->size);
365 goto out_conflict;
366 }
367 }
368 }
369#undef OVERLAPS
370
371out_no_conflict:
372 /* this is like it should be, and what we expected.
373 * our users do behave after all... */
374 put_net_conf(mdev);
375 return 0;
376
377out_conflict:
378 put_net_conf(mdev);
379 return 1;
380}
381
382/* obviously this could be coded as many single functions
383 * instead of one huge switch,
384 * or by putting the code directly in the respective locations
385 * (as it has been before).
386 *
387 * but having it this way
388 * enforces that it is all in this one place, where it is easier to audit,
389 * it makes it obvious that whatever "event" "happens" to a request should
390 * happen "atomically" within the req_lock,
391 * and it enforces that we have to think in a very structured manner
392 * about the "events" that may happen to a request during its life time ...
393 */
Philipp Reisner2a806992010-06-09 14:07:43 +0200394int __req_mod(struct drbd_request *req, enum drbd_req_event what,
Philipp Reisnerb411b362009-09-25 16:07:19 -0700395 struct bio_and_error *m)
396{
397 struct drbd_conf *mdev = req->mdev;
Philipp Reisner2a806992010-06-09 14:07:43 +0200398 int rv = 0;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700399 m->bio = NULL;
400
Philipp Reisnerb411b362009-09-25 16:07:19 -0700401 switch (what) {
402 default:
403 dev_err(DEV, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__);
404 break;
405
406 /* does not happen...
407 * initialization done in drbd_req_new
408 case created:
409 break;
410 */
411
412 case to_be_send: /* via network */
413 /* reached via drbd_make_request_common
414 * and from w_read_retry_remote */
415 D_ASSERT(!(req->rq_state & RQ_NET_MASK));
416 req->rq_state |= RQ_NET_PENDING;
417 inc_ap_pending(mdev);
418 break;
419
420 case to_be_submitted: /* locally */
421 /* reached via drbd_make_request_common */
422 D_ASSERT(!(req->rq_state & RQ_LOCAL_MASK));
423 req->rq_state |= RQ_LOCAL_PENDING;
424 break;
425
426 case completed_ok:
427 if (bio_data_dir(req->master_bio) == WRITE)
428 mdev->writ_cnt += req->size>>9;
429 else
430 mdev->read_cnt += req->size>>9;
431
432 req->rq_state |= (RQ_LOCAL_COMPLETED|RQ_LOCAL_OK);
433 req->rq_state &= ~RQ_LOCAL_PENDING;
434
Philipp Reisnercfa03412010-06-23 17:18:51 +0200435 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700436 put_ldev(mdev);
437 break;
438
439 case write_completed_with_error:
440 req->rq_state |= RQ_LOCAL_COMPLETED;
441 req->rq_state &= ~RQ_LOCAL_PENDING;
442
Philipp Reisnerb411b362009-09-25 16:07:19 -0700443 __drbd_chk_io_error(mdev, FALSE);
Philipp Reisnercfa03412010-06-23 17:18:51 +0200444 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700445 put_ldev(mdev);
446 break;
447
448 case read_ahead_completed_with_error:
449 /* it is legal to fail READA */
450 req->rq_state |= RQ_LOCAL_COMPLETED;
451 req->rq_state &= ~RQ_LOCAL_PENDING;
Philipp Reisnercfa03412010-06-23 17:18:51 +0200452 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700453 put_ldev(mdev);
454 break;
455
456 case read_completed_with_error:
457 drbd_set_out_of_sync(mdev, req->sector, req->size);
458
459 req->rq_state |= RQ_LOCAL_COMPLETED;
460 req->rq_state &= ~RQ_LOCAL_PENDING;
461
Philipp Reisnerb411b362009-09-25 16:07:19 -0700462 D_ASSERT(!(req->rq_state & RQ_NET_MASK));
Philipp Reisnerb411b362009-09-25 16:07:19 -0700463
464 __drbd_chk_io_error(mdev, FALSE);
465 put_ldev(mdev);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700466
Lars Ellenbergd255e5f2010-05-27 09:45:45 +0200467 /* no point in retrying if there is no good remote data,
468 * or we have no connection. */
469 if (mdev->state.pdsk != D_UP_TO_DATE) {
Philipp Reisnercfa03412010-06-23 17:18:51 +0200470 _req_may_be_done_not_susp(req, m);
Lars Ellenbergd255e5f2010-05-27 09:45:45 +0200471 break;
472 }
473
474 /* _req_mod(req,to_be_send); oops, recursion... */
475 req->rq_state |= RQ_NET_PENDING;
476 inc_ap_pending(mdev);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700477 /* fall through: _req_mod(req,queue_for_net_read); */
478
479 case queue_for_net_read:
480 /* READ or READA, and
481 * no local disk,
482 * or target area marked as invalid,
483 * or just got an io-error. */
484 /* from drbd_make_request_common
485 * or from bio_endio during read io-error recovery */
486
487 /* so we can verify the handle in the answer packet
488 * corresponding hlist_del is in _req_may_be_done() */
489 hlist_add_head(&req->colision, ar_hash_slot(mdev, req->sector));
490
Lars Ellenberg83c38832009-11-03 02:22:06 +0100491 set_bit(UNPLUG_REMOTE, &mdev->flags);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700492
493 D_ASSERT(req->rq_state & RQ_NET_PENDING);
494 req->rq_state |= RQ_NET_QUEUED;
495 req->w.cb = (req->rq_state & RQ_LOCAL_MASK)
496 ? w_read_retry_remote
497 : w_send_read_req;
498 drbd_queue_work(&mdev->data.work, &req->w);
499 break;
500
501 case queue_for_net_write:
502 /* assert something? */
503 /* from drbd_make_request_common only */
504
505 hlist_add_head(&req->colision, tl_hash_slot(mdev, req->sector));
506 /* corresponding hlist_del is in _req_may_be_done() */
507
508 /* NOTE
509 * In case the req ended up on the transfer log before being
510 * queued on the worker, it could lead to this request being
511 * missed during cleanup after connection loss.
512 * So we have to do both operations here,
513 * within the same lock that protects the transfer log.
514 *
515 * _req_add_to_epoch(req); this has to be after the
516 * _maybe_start_new_epoch(req); which happened in
517 * drbd_make_request_common, because we now may set the bit
518 * again ourselves to close the current epoch.
519 *
520 * Add req to the (now) current epoch (barrier). */
521
Lars Ellenberg83c38832009-11-03 02:22:06 +0100522 /* otherwise we may lose an unplug, which may cause some remote
523 * io-scheduler timeout to expire, increasing maximum latency,
524 * hurting performance. */
525 set_bit(UNPLUG_REMOTE, &mdev->flags);
526
Philipp Reisnerb411b362009-09-25 16:07:19 -0700527 /* see drbd_make_request_common,
528 * just after it grabs the req_lock */
529 D_ASSERT(test_bit(CREATE_BARRIER, &mdev->flags) == 0);
530
531 req->epoch = mdev->newest_tle->br_number;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700532
533 /* increment size of current epoch */
Philipp Reisner7e602c02010-05-27 14:49:27 +0200534 mdev->newest_tle->n_writes++;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700535
536 /* queue work item to send data */
537 D_ASSERT(req->rq_state & RQ_NET_PENDING);
538 req->rq_state |= RQ_NET_QUEUED;
539 req->w.cb = w_send_dblock;
540 drbd_queue_work(&mdev->data.work, &req->w);
541
542 /* close the epoch, in case it outgrew the limit */
Philipp Reisner7e602c02010-05-27 14:49:27 +0200543 if (mdev->newest_tle->n_writes >= mdev->net_conf->max_epoch_size)
Philipp Reisnerb411b362009-09-25 16:07:19 -0700544 queue_barrier(mdev);
545
546 break;
547
548 case send_canceled:
549 /* treat it the same */
550 case send_failed:
551 /* real cleanup will be done from tl_clear. just update flags
552 * so it is no longer marked as on the worker queue */
553 req->rq_state &= ~RQ_NET_QUEUED;
554 /* if we did it right, tl_clear should be scheduled only after
555 * this, so this should not be necessary! */
Philipp Reisnercfa03412010-06-23 17:18:51 +0200556 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700557 break;
558
559 case handed_over_to_network:
560 /* assert something? */
561 if (bio_data_dir(req->master_bio) == WRITE &&
562 mdev->net_conf->wire_protocol == DRBD_PROT_A) {
563 /* this is what is dangerous about protocol A:
564 * pretend it was successfully written on the peer. */
565 if (req->rq_state & RQ_NET_PENDING) {
566 dec_ap_pending(mdev);
567 req->rq_state &= ~RQ_NET_PENDING;
568 req->rq_state |= RQ_NET_OK;
569 } /* else: neg-ack was faster... */
570 /* it is still not yet RQ_NET_DONE until the
571 * corresponding epoch barrier got acked as well,
572 * so we know what to dirty on connection loss */
573 }
574 req->rq_state &= ~RQ_NET_QUEUED;
575 req->rq_state |= RQ_NET_SENT;
576 /* because _drbd_send_zc_bio could sleep, and may want to
577 * dereference the bio even after the "write_acked_by_peer" and
578 * "completed_ok" events came in, once we return from
579 * _drbd_send_zc_bio (drbd_send_dblock), we have to check
580 * whether it is done already, and end it. */
Philipp Reisnercfa03412010-06-23 17:18:51 +0200581 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700582 break;
583
Lars Ellenbergd255e5f2010-05-27 09:45:45 +0200584 case read_retry_remote_canceled:
585 req->rq_state &= ~RQ_NET_QUEUED;
586 /* fall through, in case we raced with drbd_disconnect */
Philipp Reisnerb411b362009-09-25 16:07:19 -0700587 case connection_lost_while_pending:
588 /* transfer log cleanup after connection loss */
589 /* assert something? */
590 if (req->rq_state & RQ_NET_PENDING)
591 dec_ap_pending(mdev);
592 req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING);
593 req->rq_state |= RQ_NET_DONE;
594 /* if it is still queued, we may not complete it here.
595 * it will be canceled soon. */
596 if (!(req->rq_state & RQ_NET_QUEUED))
Philipp Reisnercfa03412010-06-23 17:18:51 +0200597 _req_may_be_done(req, m); /* Allowed while state.susp */
Philipp Reisnerb411b362009-09-25 16:07:19 -0700598 break;
599
600 case write_acked_by_peer_and_sis:
601 req->rq_state |= RQ_NET_SIS;
602 case conflict_discarded_by_peer:
603 /* for discarded conflicting writes of multiple primaries,
604 * there is no need to keep anything in the tl, potential
605 * node crashes are covered by the activity log. */
606 if (what == conflict_discarded_by_peer)
607 dev_alert(DEV, "Got DiscardAck packet %llus +%u!"
608 " DRBD is not a random data generator!\n",
609 (unsigned long long)req->sector, req->size);
610 req->rq_state |= RQ_NET_DONE;
611 /* fall through */
612 case write_acked_by_peer:
613 /* protocol C; successfully written on peer.
614 * Nothing to do here.
615 * We want to keep the tl in place for all protocols, to cater
616 * for volatile write-back caches on lower level devices.
617 *
618 * A barrier request is expected to have forced all prior
619 * requests onto stable storage, so completion of a barrier
620 * request could set NET_DONE right here, and not wait for the
621 * P_BARRIER_ACK, but that is an unnecessary optimization. */
622
623 /* this makes it effectively the same as for: */
624 case recv_acked_by_peer:
625 /* protocol B; pretends to be successfully written on peer.
626 * see also notes above in handed_over_to_network about
627 * protocol != C */
628 req->rq_state |= RQ_NET_OK;
629 D_ASSERT(req->rq_state & RQ_NET_PENDING);
630 dec_ap_pending(mdev);
631 req->rq_state &= ~RQ_NET_PENDING;
Philipp Reisnercfa03412010-06-23 17:18:51 +0200632 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700633 break;
634
635 case neg_acked:
636 /* assert something? */
637 if (req->rq_state & RQ_NET_PENDING)
638 dec_ap_pending(mdev);
639 req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING);
640
641 req->rq_state |= RQ_NET_DONE;
Philipp Reisnercfa03412010-06-23 17:18:51 +0200642 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700643 /* else: done by handed_over_to_network */
644 break;
645
Philipp Reisner265be2d2010-05-31 10:14:17 +0200646 case fail_frozen_disk_io:
647 if (!(req->rq_state & RQ_LOCAL_COMPLETED))
648 break;
649
Philipp Reisnercfa03412010-06-23 17:18:51 +0200650 _req_may_be_done(req, m); /* Allowed while state.susp */
Philipp Reisner265be2d2010-05-31 10:14:17 +0200651 break;
652
653 case restart_frozen_disk_io:
654 if (!(req->rq_state & RQ_LOCAL_COMPLETED))
655 break;
656
657 req->rq_state &= ~RQ_LOCAL_COMPLETED;
658
659 rv = MR_READ;
660 if (bio_data_dir(req->master_bio) == WRITE)
661 rv = MR_WRITE;
662
663 get_ldev(mdev);
664 req->w.cb = w_restart_disk_io;
665 drbd_queue_work(&mdev->data.work, &req->w);
666 break;
667
Philipp Reisner11b58e72010-05-12 17:08:26 +0200668 case resend:
669 /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK
Philipp Reisner47ff2d02010-06-18 13:56:57 +0200670 before the connection loss (B&C only); only P_BARRIER_ACK was missing.
Philipp Reisner11b58e72010-05-12 17:08:26 +0200671 Trowing them out of the TL here by pretending we got a BARRIER_ACK
Philipp Reisner481c6f52010-06-22 14:03:27 +0200672 We ensure that the peer was not rebooted */
Philipp Reisner11b58e72010-05-12 17:08:26 +0200673 if (!(req->rq_state & RQ_NET_OK)) {
674 if (req->w.cb) {
675 drbd_queue_work(&mdev->data.work, &req->w);
676 rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ;
677 }
678 break;
679 }
680 /* else, fall through to barrier_acked */
681
Philipp Reisnerb411b362009-09-25 16:07:19 -0700682 case barrier_acked:
Philipp Reisner288f4222010-05-27 15:07:43 +0200683 if (!(req->rq_state & RQ_WRITE))
684 break;
685
Philipp Reisnerb411b362009-09-25 16:07:19 -0700686 if (req->rq_state & RQ_NET_PENDING) {
687 /* barrier came in before all requests have been acked.
688 * this is bad, because if the connection is lost now,
689 * we won't be able to clean them up... */
690 dev_err(DEV, "FIXME (barrier_acked but pending)\n");
Philipp Reisnerb411b362009-09-25 16:07:19 -0700691 list_move(&req->tl_requests, &mdev->out_of_sequence_requests);
692 }
693 D_ASSERT(req->rq_state & RQ_NET_SENT);
694 req->rq_state |= RQ_NET_DONE;
Philipp Reisnercfa03412010-06-23 17:18:51 +0200695 _req_may_be_done(req, m); /* Allowed while state.susp */
Philipp Reisnerb411b362009-09-25 16:07:19 -0700696 break;
697
698 case data_received:
699 D_ASSERT(req->rq_state & RQ_NET_PENDING);
700 dec_ap_pending(mdev);
701 req->rq_state &= ~RQ_NET_PENDING;
702 req->rq_state |= (RQ_NET_OK|RQ_NET_DONE);
Philipp Reisnercfa03412010-06-23 17:18:51 +0200703 _req_may_be_done_not_susp(req, m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700704 break;
705 };
Philipp Reisner2a806992010-06-09 14:07:43 +0200706
707 return rv;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700708}
709
710/* we may do a local read if:
711 * - we are consistent (of course),
712 * - or we are generally inconsistent,
713 * BUT we are still/already IN SYNC for this area.
714 * since size may be bigger than BM_BLOCK_SIZE,
715 * we may need to check several bits.
716 */
717static int drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size)
718{
719 unsigned long sbnr, ebnr;
720 sector_t esector, nr_sectors;
721
722 if (mdev->state.disk == D_UP_TO_DATE)
723 return 1;
724 if (mdev->state.disk >= D_OUTDATED)
725 return 0;
726 if (mdev->state.disk < D_INCONSISTENT)
727 return 0;
728 /* state.disk == D_INCONSISTENT We will have a look at the BitMap */
729 nr_sectors = drbd_get_capacity(mdev->this_bdev);
730 esector = sector + (size >> 9) - 1;
731
732 D_ASSERT(sector < nr_sectors);
733 D_ASSERT(esector < nr_sectors);
734
735 sbnr = BM_SECT_TO_BIT(sector);
736 ebnr = BM_SECT_TO_BIT(esector);
737
738 return 0 == drbd_bm_count_bits(mdev, sbnr, ebnr);
739}
740
741static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio)
742{
743 const int rw = bio_rw(bio);
744 const int size = bio->bi_size;
745 const sector_t sector = bio->bi_sector;
746 struct drbd_tl_epoch *b = NULL;
747 struct drbd_request *req;
748 int local, remote;
749 int err = -EIO;
Philipp Reisner9a25a042010-05-10 16:42:23 +0200750 int ret = 0;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700751
752 /* allocate outside of all locks; */
753 req = drbd_req_new(mdev, bio);
754 if (!req) {
755 dec_ap_bio(mdev);
756 /* only pass the error to the upper layers.
757 * if user cannot handle io errors, that's not our business. */
758 dev_err(DEV, "could not kmalloc() req\n");
759 bio_endio(bio, -ENOMEM);
760 return 0;
761 }
762
Philipp Reisnerb411b362009-09-25 16:07:19 -0700763 local = get_ldev(mdev);
764 if (!local) {
765 bio_put(req->private_bio); /* or we get a bio leak */
766 req->private_bio = NULL;
767 }
768 if (rw == WRITE) {
769 remote = 1;
770 } else {
771 /* READ || READA */
772 if (local) {
773 if (!drbd_may_do_local_read(mdev, sector, size)) {
774 /* we could kick the syncer to
775 * sync this extent asap, wait for
776 * it, then continue locally.
777 * Or just issue the request remotely.
778 */
779 local = 0;
780 bio_put(req->private_bio);
781 req->private_bio = NULL;
782 put_ldev(mdev);
783 }
784 }
785 remote = !local && mdev->state.pdsk >= D_UP_TO_DATE;
786 }
787
788 /* If we have a disk, but a READA request is mapped to remote,
789 * we are R_PRIMARY, D_INCONSISTENT, SyncTarget.
790 * Just fail that READA request right here.
791 *
792 * THINK: maybe fail all READA when not local?
793 * or make this configurable...
794 * if network is slow, READA won't do any good.
795 */
796 if (rw == READA && mdev->state.disk >= D_INCONSISTENT && !local) {
797 err = -EWOULDBLOCK;
798 goto fail_and_free_req;
799 }
800
801 /* For WRITES going to the local disk, grab a reference on the target
802 * extent. This waits for any resync activity in the corresponding
803 * resync extent to finish, and, if necessary, pulls in the target
804 * extent into the activity log, which involves further disk io because
805 * of transactional on-disk meta data updates. */
Philipp Reisner07782862010-08-31 12:00:50 +0200806 if (rw == WRITE && local && !test_bit(AL_SUSPENDED, &mdev->flags)) {
807 req->rq_state |= RQ_IN_ACT_LOG;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700808 drbd_al_begin_io(mdev, sector);
Philipp Reisner07782862010-08-31 12:00:50 +0200809 }
Philipp Reisnerb411b362009-09-25 16:07:19 -0700810
811 remote = remote && (mdev->state.pdsk == D_UP_TO_DATE ||
812 (mdev->state.pdsk == D_INCONSISTENT &&
813 mdev->state.conn >= C_CONNECTED));
814
Philipp Reisnerfb22c402010-09-08 23:20:21 +0200815 if (!(local || remote) && !is_susp(mdev->state)) {
Lars Ellenbergfb2c7a12010-10-19 12:08:13 +0200816 if (__ratelimit(&drbd_ratelimit_state))
817 dev_err(DEV, "IO ERROR: neither local nor remote disk\n");
Philipp Reisnerb411b362009-09-25 16:07:19 -0700818 goto fail_free_complete;
819 }
820
821 /* For WRITE request, we have to make sure that we have an
822 * unused_spare_tle, in case we need to start a new epoch.
823 * I try to be smart and avoid to pre-allocate always "just in case",
824 * but there is a race between testing the bit and pointer outside the
825 * spinlock, and grabbing the spinlock.
826 * if we lost that race, we retry. */
827 if (rw == WRITE && remote &&
828 mdev->unused_spare_tle == NULL &&
829 test_bit(CREATE_BARRIER, &mdev->flags)) {
830allocate_barrier:
831 b = kmalloc(sizeof(struct drbd_tl_epoch), GFP_NOIO);
832 if (!b) {
833 dev_err(DEV, "Failed to alloc barrier.\n");
834 err = -ENOMEM;
835 goto fail_free_complete;
836 }
837 }
838
839 /* GOOD, everything prepared, grab the spin_lock */
840 spin_lock_irq(&mdev->req_lock);
841
Philipp Reisnerfb22c402010-09-08 23:20:21 +0200842 if (is_susp(mdev->state)) {
Philipp Reisner9a25a042010-05-10 16:42:23 +0200843 /* If we got suspended, use the retry mechanism of
844 generic_make_request() to restart processing of this
845 bio. In the next call to drbd_make_request_26
846 we sleep in inc_ap_bio() */
847 ret = 1;
848 spin_unlock_irq(&mdev->req_lock);
849 goto fail_free_complete;
850 }
851
Philipp Reisnerb411b362009-09-25 16:07:19 -0700852 if (remote) {
853 remote = (mdev->state.pdsk == D_UP_TO_DATE ||
854 (mdev->state.pdsk == D_INCONSISTENT &&
855 mdev->state.conn >= C_CONNECTED));
856 if (!remote)
857 dev_warn(DEV, "lost connection while grabbing the req_lock!\n");
858 if (!(local || remote)) {
859 dev_err(DEV, "IO ERROR: neither local nor remote disk\n");
860 spin_unlock_irq(&mdev->req_lock);
861 goto fail_free_complete;
862 }
863 }
864
865 if (b && mdev->unused_spare_tle == NULL) {
866 mdev->unused_spare_tle = b;
867 b = NULL;
868 }
869 if (rw == WRITE && remote &&
870 mdev->unused_spare_tle == NULL &&
871 test_bit(CREATE_BARRIER, &mdev->flags)) {
872 /* someone closed the current epoch
873 * while we were grabbing the spinlock */
874 spin_unlock_irq(&mdev->req_lock);
875 goto allocate_barrier;
876 }
877
878
879 /* Update disk stats */
880 _drbd_start_io_acct(mdev, req, bio);
881
882 /* _maybe_start_new_epoch(mdev);
883 * If we need to generate a write barrier packet, we have to add the
884 * new epoch (barrier) object, and queue the barrier packet for sending,
885 * and queue the req's data after it _within the same lock_, otherwise
886 * we have race conditions were the reorder domains could be mixed up.
887 *
888 * Even read requests may start a new epoch and queue the corresponding
889 * barrier packet. To get the write ordering right, we only have to
890 * make sure that, if this is a write request and it triggered a
891 * barrier packet, this request is queued within the same spinlock. */
892 if (remote && mdev->unused_spare_tle &&
893 test_and_clear_bit(CREATE_BARRIER, &mdev->flags)) {
894 _tl_add_barrier(mdev, mdev->unused_spare_tle);
895 mdev->unused_spare_tle = NULL;
896 } else {
897 D_ASSERT(!(remote && rw == WRITE &&
898 test_bit(CREATE_BARRIER, &mdev->flags)));
899 }
900
901 /* NOTE
902 * Actually, 'local' may be wrong here already, since we may have failed
903 * to write to the meta data, and may become wrong anytime because of
904 * local io-error for some other request, which would lead to us
905 * "detaching" the local disk.
906 *
907 * 'remote' may become wrong any time because the network could fail.
908 *
909 * This is a harmless race condition, though, since it is handled
910 * correctly at the appropriate places; so it just defers the failure
911 * of the respective operation.
912 */
913
914 /* mark them early for readability.
915 * this just sets some state flags. */
916 if (remote)
917 _req_mod(req, to_be_send);
918 if (local)
919 _req_mod(req, to_be_submitted);
920
921 /* check this request on the collision detection hash tables.
922 * if we have a conflict, just complete it here.
923 * THINK do we want to check reads, too? (I don't think so...) */
Lars Ellenbergd28fd092010-07-09 23:28:10 +0200924 if (rw == WRITE && _req_conflicts(req))
925 goto fail_conflicting;
Philipp Reisner288f4222010-05-27 15:07:43 +0200926
927 list_add_tail(&req->tl_requests, &mdev->newest_tle->requests);
928
Philipp Reisnerb411b362009-09-25 16:07:19 -0700929 /* NOTE remote first: to get the concurrent write detection right,
930 * we must register the request before start of local IO. */
931 if (remote) {
932 /* either WRITE and C_CONNECTED,
933 * or READ, and no local disk,
934 * or READ, but not in sync.
935 */
936 _req_mod(req, (rw == WRITE)
937 ? queue_for_net_write
938 : queue_for_net_read);
939 }
940 spin_unlock_irq(&mdev->req_lock);
941 kfree(b); /* if someone else has beaten us to it... */
942
943 if (local) {
944 req->private_bio->bi_bdev = mdev->ldev->backing_bdev;
945
Lars Ellenberg6719fb02010-10-18 23:04:07 +0200946 /* State may have changed since we grabbed our reference on the
947 * mdev->ldev member. Double check, and short-circuit to endio.
948 * In case the last activity log transaction failed to get on
949 * stable storage, and this is a WRITE, we may not even submit
950 * this bio. */
951 if (get_ldev(mdev)) {
952 if (FAULT_ACTIVE(mdev, rw == WRITE ? DRBD_FAULT_DT_WR
953 : rw == READ ? DRBD_FAULT_DT_RD
954 : DRBD_FAULT_DT_RA))
955 bio_endio(req->private_bio, -EIO);
956 else
957 generic_make_request(req->private_bio);
958 put_ldev(mdev);
959 } else
Philipp Reisnerb411b362009-09-25 16:07:19 -0700960 bio_endio(req->private_bio, -EIO);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700961 }
962
963 /* we need to plug ALWAYS since we possibly need to kick lo_dev.
964 * we plug after submit, so we won't miss an unplug event */
965 drbd_plug_device(mdev);
966
967 return 0;
968
Lars Ellenbergd28fd092010-07-09 23:28:10 +0200969fail_conflicting:
970 /* this is a conflicting request.
971 * even though it may have been only _partially_
972 * overlapping with one of the currently pending requests,
973 * without even submitting or sending it, we will
974 * pretend that it was successfully served right now.
975 */
976 _drbd_end_io_acct(mdev, req);
977 spin_unlock_irq(&mdev->req_lock);
978 if (remote)
979 dec_ap_pending(mdev);
980 /* THINK: do we want to fail it (-EIO), or pretend success?
981 * this pretends success. */
982 err = 0;
983
Philipp Reisnerb411b362009-09-25 16:07:19 -0700984fail_free_complete:
985 if (rw == WRITE && local)
986 drbd_al_complete_io(mdev, sector);
987fail_and_free_req:
988 if (local) {
989 bio_put(req->private_bio);
990 req->private_bio = NULL;
991 put_ldev(mdev);
992 }
Philipp Reisner9a25a042010-05-10 16:42:23 +0200993 if (!ret)
994 bio_endio(bio, err);
995
Philipp Reisnerb411b362009-09-25 16:07:19 -0700996 drbd_req_free(req);
997 dec_ap_bio(mdev);
998 kfree(b);
999
Philipp Reisner9a25a042010-05-10 16:42:23 +02001000 return ret;
Philipp Reisnerb411b362009-09-25 16:07:19 -07001001}
1002
1003/* helper function for drbd_make_request
1004 * if we can determine just by the mdev (state) that this request will fail,
1005 * return 1
1006 * otherwise return 0
1007 */
1008static int drbd_fail_request_early(struct drbd_conf *mdev, int is_write)
1009{
Philipp Reisnerb411b362009-09-25 16:07:19 -07001010 if (mdev->state.role != R_PRIMARY &&
1011 (!allow_oos || is_write)) {
1012 if (__ratelimit(&drbd_ratelimit_state)) {
1013 dev_err(DEV, "Process %s[%u] tried to %s; "
1014 "since we are not in Primary state, "
1015 "we cannot allow this\n",
1016 current->comm, current->pid,
1017 is_write ? "WRITE" : "READ");
1018 }
1019 return 1;
1020 }
1021
Philipp Reisnerb411b362009-09-25 16:07:19 -07001022 return 0;
1023}
1024
1025int drbd_make_request_26(struct request_queue *q, struct bio *bio)
1026{
1027 unsigned int s_enr, e_enr;
1028 struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata;
1029
1030 if (drbd_fail_request_early(mdev, bio_data_dir(bio) & WRITE)) {
1031 bio_endio(bio, -EPERM);
1032 return 0;
1033 }
1034
Philipp Reisnerb411b362009-09-25 16:07:19 -07001035 /*
1036 * what we "blindly" assume:
1037 */
1038 D_ASSERT(bio->bi_size > 0);
1039 D_ASSERT((bio->bi_size & 0x1ff) == 0);
1040 D_ASSERT(bio->bi_idx == 0);
1041
1042 /* to make some things easier, force alignment of requests within the
1043 * granularity of our hash tables */
1044 s_enr = bio->bi_sector >> HT_SHIFT;
1045 e_enr = (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT;
1046
1047 if (likely(s_enr == e_enr)) {
1048 inc_ap_bio(mdev, 1);
1049 return drbd_make_request_common(mdev, bio);
1050 }
1051
1052 /* can this bio be split generically?
1053 * Maybe add our own split-arbitrary-bios function. */
1054 if (bio->bi_vcnt != 1 || bio->bi_idx != 0 || bio->bi_size > DRBD_MAX_SEGMENT_SIZE) {
1055 /* rather error out here than BUG in bio_split */
1056 dev_err(DEV, "bio would need to, but cannot, be split: "
1057 "(vcnt=%u,idx=%u,size=%u,sector=%llu)\n",
1058 bio->bi_vcnt, bio->bi_idx, bio->bi_size,
1059 (unsigned long long)bio->bi_sector);
1060 bio_endio(bio, -EINVAL);
1061 } else {
1062 /* This bio crosses some boundary, so we have to split it. */
1063 struct bio_pair *bp;
1064 /* works for the "do not cross hash slot boundaries" case
1065 * e.g. sector 262269, size 4096
1066 * s_enr = 262269 >> 6 = 4097
1067 * e_enr = (262269+8-1) >> 6 = 4098
1068 * HT_SHIFT = 6
1069 * sps = 64, mask = 63
1070 * first_sectors = 64 - (262269 & 63) = 3
1071 */
1072 const sector_t sect = bio->bi_sector;
1073 const int sps = 1 << HT_SHIFT; /* sectors per slot */
1074 const int mask = sps - 1;
1075 const sector_t first_sectors = sps - (sect & mask);
1076 bp = bio_split(bio,
1077#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
1078 bio_split_pool,
1079#endif
1080 first_sectors);
1081
1082 /* we need to get a "reference count" (ap_bio_cnt)
1083 * to avoid races with the disconnect/reconnect/suspend code.
Philipp Reisner9a25a042010-05-10 16:42:23 +02001084 * In case we need to split the bio here, we need to get three references
Philipp Reisnerb411b362009-09-25 16:07:19 -07001085 * atomically, otherwise we might deadlock when trying to submit the
1086 * second one! */
Philipp Reisner9a25a042010-05-10 16:42:23 +02001087 inc_ap_bio(mdev, 3);
Philipp Reisnerb411b362009-09-25 16:07:19 -07001088
1089 D_ASSERT(e_enr == s_enr + 1);
1090
Philipp Reisner9a25a042010-05-10 16:42:23 +02001091 while (drbd_make_request_common(mdev, &bp->bio1))
1092 inc_ap_bio(mdev, 1);
1093
1094 while (drbd_make_request_common(mdev, &bp->bio2))
1095 inc_ap_bio(mdev, 1);
1096
1097 dec_ap_bio(mdev);
1098
Philipp Reisnerb411b362009-09-25 16:07:19 -07001099 bio_pair_release(bp);
1100 }
1101 return 0;
1102}
1103
1104/* This is called by bio_add_page(). With this function we reduce
1105 * the number of BIOs that span over multiple DRBD_MAX_SEGMENT_SIZEs
1106 * units (was AL_EXTENTs).
1107 *
1108 * we do the calculation within the lower 32bit of the byte offsets,
1109 * since we don't care for actual offset, but only check whether it
1110 * would cross "activity log extent" boundaries.
1111 *
1112 * As long as the BIO is empty we have to allow at least one bvec,
1113 * regardless of size and offset. so the resulting bio may still
1114 * cross extent boundaries. those are dealt with (bio_split) in
1115 * drbd_make_request_26.
1116 */
1117int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)
1118{
1119 struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata;
1120 unsigned int bio_offset =
1121 (unsigned int)bvm->bi_sector << 9; /* 32 bit */
1122 unsigned int bio_size = bvm->bi_size;
1123 int limit, backing_limit;
1124
1125 limit = DRBD_MAX_SEGMENT_SIZE
1126 - ((bio_offset & (DRBD_MAX_SEGMENT_SIZE-1)) + bio_size);
1127 if (limit < 0)
1128 limit = 0;
1129 if (bio_size == 0) {
1130 if (limit <= bvec->bv_len)
1131 limit = bvec->bv_len;
1132 } else if (limit && get_ldev(mdev)) {
1133 struct request_queue * const b =
1134 mdev->ldev->backing_bdev->bd_disk->queue;
Lars Ellenberga1c88d02010-05-14 19:16:41 +02001135 if (b->merge_bvec_fn) {
Philipp Reisnerb411b362009-09-25 16:07:19 -07001136 backing_limit = b->merge_bvec_fn(b, bvm, bvec);
1137 limit = min(limit, backing_limit);
1138 }
1139 put_ldev(mdev);
1140 }
1141 return limit;
1142}