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b411b363 PR |
1 | /* |
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 | ||
b411b363 PR |
26 | #include <linux/module.h> |
27 | ||
28 | #include <linux/slab.h> | |
29 | #include <linux/drbd.h> | |
30 | #include "drbd_int.h" | |
b411b363 PR |
31 | #include "drbd_req.h" |
32 | ||
33 | ||
34 | /* Update disk stats at start of I/O request */ | |
35 | static 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)); | |
753c8913 | 42 | part_inc_in_flight(&mdev->vdisk->part0, rw); |
b411b363 | 43 | part_stat_unlock(); |
b411b363 PR |
44 | } |
45 | ||
46 | /* Update disk stats when completing request upwards */ | |
47 | static 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); | |
753c8913 | 55 | part_dec_in_flight(&mdev->vdisk->part0, rw); |
b411b363 | 56 | part_stat_unlock(); |
b411b363 PR |
57 | } |
58 | ||
59 | static void _req_is_done(struct drbd_conf *mdev, struct drbd_request *req, const int rw) | |
60 | { | |
61 | const unsigned long s = req->rq_state; | |
62 | /* if it was a write, we may have to set the corresponding | |
63 | * bit(s) out-of-sync first. If it had a local part, we need to | |
64 | * release the reference to the activity log. */ | |
65 | if (rw == WRITE) { | |
66 | /* remove it from the transfer log. | |
67 | * well, only if it had been there in the first | |
68 | * place... if it had not (local only or conflicting | |
69 | * and never sent), it should still be "empty" as | |
70 | * initialized in drbd_req_new(), so we can list_del() it | |
71 | * here unconditionally */ | |
72 | list_del(&req->tl_requests); | |
73 | /* Set out-of-sync unless both OK flags are set | |
74 | * (local only or remote failed). | |
75 | * Other places where we set out-of-sync: | |
76 | * READ with local io-error */ | |
77 | if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK)) | |
78 | drbd_set_out_of_sync(mdev, req->sector, req->size); | |
79 | ||
80 | if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS)) | |
81 | drbd_set_in_sync(mdev, req->sector, req->size); | |
82 | ||
83 | /* one might be tempted to move the drbd_al_complete_io | |
84 | * to the local io completion callback drbd_endio_pri. | |
85 | * but, if this was a mirror write, we may only | |
86 | * drbd_al_complete_io after this is RQ_NET_DONE, | |
87 | * otherwise the extent could be dropped from the al | |
88 | * before it has actually been written on the peer. | |
89 | * if we crash before our peer knows about the request, | |
90 | * but after the extent has been dropped from the al, | |
91 | * we would forget to resync the corresponding extent. | |
92 | */ | |
93 | if (s & RQ_LOCAL_MASK) { | |
94 | if (get_ldev_if_state(mdev, D_FAILED)) { | |
95 | drbd_al_complete_io(mdev, req->sector); | |
96 | put_ldev(mdev); | |
97 | } else if (__ratelimit(&drbd_ratelimit_state)) { | |
98 | dev_warn(DEV, "Should have called drbd_al_complete_io(, %llu), " | |
99 | "but my Disk seems to have failed :(\n", | |
100 | (unsigned long long) req->sector); | |
101 | } | |
102 | } | |
103 | } | |
104 | ||
105 | /* if it was a local io error, we want to notify our | |
106 | * peer about that, and see if we need to | |
107 | * detach the disk and stuff. | |
108 | * to avoid allocating some special work | |
109 | * struct, reuse the request. */ | |
110 | ||
111 | /* THINK | |
112 | * why do we do this not when we detect the error, | |
113 | * but delay it until it is "done", i.e. possibly | |
114 | * until the next barrier ack? */ | |
115 | ||
116 | if (rw == WRITE && | |
117 | ((s & RQ_LOCAL_MASK) && !(s & RQ_LOCAL_OK))) { | |
118 | if (!(req->w.list.next == LIST_POISON1 || | |
119 | list_empty(&req->w.list))) { | |
120 | /* DEBUG ASSERT only; if this triggers, we | |
121 | * probably corrupt the worker list here */ | |
122 | dev_err(DEV, "req->w.list.next = %p\n", req->w.list.next); | |
123 | dev_err(DEV, "req->w.list.prev = %p\n", req->w.list.prev); | |
124 | } | |
125 | req->w.cb = w_io_error; | |
126 | drbd_queue_work(&mdev->data.work, &req->w); | |
127 | /* drbd_req_free() is done in w_io_error */ | |
128 | } else { | |
129 | drbd_req_free(req); | |
130 | } | |
131 | } | |
132 | ||
133 | static void queue_barrier(struct drbd_conf *mdev) | |
134 | { | |
135 | struct drbd_tl_epoch *b; | |
136 | ||
137 | /* We are within the req_lock. Once we queued the barrier for sending, | |
138 | * we set the CREATE_BARRIER bit. It is cleared as soon as a new | |
139 | * barrier/epoch object is added. This is the only place this bit is | |
140 | * set. It indicates that the barrier for this epoch is already queued, | |
141 | * and no new epoch has been created yet. */ | |
142 | if (test_bit(CREATE_BARRIER, &mdev->flags)) | |
143 | return; | |
144 | ||
145 | b = mdev->newest_tle; | |
146 | b->w.cb = w_send_barrier; | |
147 | /* inc_ap_pending done here, so we won't | |
148 | * get imbalanced on connection loss. | |
149 | * dec_ap_pending will be done in got_BarrierAck | |
150 | * or (on connection loss) in tl_clear. */ | |
151 | inc_ap_pending(mdev); | |
152 | drbd_queue_work(&mdev->data.work, &b->w); | |
153 | set_bit(CREATE_BARRIER, &mdev->flags); | |
154 | } | |
155 | ||
156 | static void _about_to_complete_local_write(struct drbd_conf *mdev, | |
157 | struct drbd_request *req) | |
158 | { | |
159 | const unsigned long s = req->rq_state; | |
160 | struct drbd_request *i; | |
161 | struct drbd_epoch_entry *e; | |
162 | struct hlist_node *n; | |
163 | struct hlist_head *slot; | |
164 | ||
165 | /* before we can signal completion to the upper layers, | |
166 | * we may need to close the current epoch */ | |
167 | if (mdev->state.conn >= C_CONNECTED && | |
168 | req->epoch == mdev->newest_tle->br_number) | |
169 | queue_barrier(mdev); | |
170 | ||
171 | /* we need to do the conflict detection stuff, | |
172 | * if we have the ee_hash (two_primaries) and | |
173 | * this has been on the network */ | |
174 | if ((s & RQ_NET_DONE) && mdev->ee_hash != NULL) { | |
175 | const sector_t sector = req->sector; | |
176 | const int size = req->size; | |
177 | ||
178 | /* ASSERT: | |
179 | * there must be no conflicting requests, since | |
180 | * they must have been failed on the spot */ | |
181 | #define OVERLAPS overlaps(sector, size, i->sector, i->size) | |
182 | slot = tl_hash_slot(mdev, sector); | |
183 | hlist_for_each_entry(i, n, slot, colision) { | |
184 | if (OVERLAPS) { | |
185 | dev_alert(DEV, "LOGIC BUG: completed: %p %llus +%u; " | |
186 | "other: %p %llus +%u\n", | |
187 | req, (unsigned long long)sector, size, | |
188 | i, (unsigned long long)i->sector, i->size); | |
189 | } | |
190 | } | |
191 | ||
192 | /* maybe "wake" those conflicting epoch entries | |
193 | * that wait for this request to finish. | |
194 | * | |
195 | * currently, there can be only _one_ such ee | |
196 | * (well, or some more, which would be pending | |
197 | * P_DISCARD_ACK not yet sent by the asender...), | |
198 | * since we block the receiver thread upon the | |
199 | * first conflict detection, which will wait on | |
200 | * misc_wait. maybe we want to assert that? | |
201 | * | |
202 | * anyways, if we found one, | |
203 | * we just have to do a wake_up. */ | |
204 | #undef OVERLAPS | |
205 | #define OVERLAPS overlaps(sector, size, e->sector, e->size) | |
206 | slot = ee_hash_slot(mdev, req->sector); | |
207 | hlist_for_each_entry(e, n, slot, colision) { | |
208 | if (OVERLAPS) { | |
209 | wake_up(&mdev->misc_wait); | |
210 | break; | |
211 | } | |
212 | } | |
213 | } | |
214 | #undef OVERLAPS | |
215 | } | |
216 | ||
217 | void complete_master_bio(struct drbd_conf *mdev, | |
218 | struct bio_and_error *m) | |
219 | { | |
b411b363 PR |
220 | bio_endio(m->bio, m->error); |
221 | dec_ap_bio(mdev); | |
222 | } | |
223 | ||
224 | /* Helper for __req_mod(). | |
225 | * Set m->bio to the master bio, if it is fit to be completed, | |
226 | * or leave it alone (it is initialized to NULL in __req_mod), | |
227 | * if it has already been completed, or cannot be completed yet. | |
228 | * If m->bio is set, the error status to be returned is placed in m->error. | |
229 | */ | |
230 | void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m) | |
231 | { | |
232 | const unsigned long s = req->rq_state; | |
233 | struct drbd_conf *mdev = req->mdev; | |
234 | /* only WRITES may end up here without a master bio (on barrier ack) */ | |
235 | int rw = req->master_bio ? bio_data_dir(req->master_bio) : WRITE; | |
236 | ||
b411b363 PR |
237 | /* we must not complete the master bio, while it is |
238 | * still being processed by _drbd_send_zc_bio (drbd_send_dblock) | |
239 | * not yet acknowledged by the peer | |
240 | * not yet completed by the local io subsystem | |
241 | * these flags may get cleared in any order by | |
242 | * the worker, | |
243 | * the receiver, | |
244 | * the bio_endio completion callbacks. | |
245 | */ | |
246 | if (s & RQ_NET_QUEUED) | |
247 | return; | |
248 | if (s & RQ_NET_PENDING) | |
249 | return; | |
250 | if (s & RQ_LOCAL_PENDING) | |
251 | return; | |
252 | ||
253 | if (req->master_bio) { | |
254 | /* this is data_received (remote read) | |
255 | * or protocol C P_WRITE_ACK | |
256 | * or protocol B P_RECV_ACK | |
257 | * or protocol A "handed_over_to_network" (SendAck) | |
258 | * or canceled or failed, | |
259 | * or killed from the transfer log due to connection loss. | |
260 | */ | |
261 | ||
262 | /* | |
263 | * figure out whether to report success or failure. | |
264 | * | |
265 | * report success when at least one of the operations succeeded. | |
266 | * or, to put the other way, | |
267 | * only report failure, when both operations failed. | |
268 | * | |
269 | * what to do about the failures is handled elsewhere. | |
270 | * what we need to do here is just: complete the master_bio. | |
271 | * | |
272 | * local completion error, if any, has been stored as ERR_PTR | |
273 | * in private_bio within drbd_endio_pri. | |
274 | */ | |
275 | int ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK); | |
276 | int error = PTR_ERR(req->private_bio); | |
277 | ||
278 | /* remove the request from the conflict detection | |
279 | * respective block_id verification hash */ | |
280 | if (!hlist_unhashed(&req->colision)) | |
281 | hlist_del(&req->colision); | |
282 | else | |
283 | D_ASSERT((s & RQ_NET_MASK) == 0); | |
284 | ||
285 | /* for writes we need to do some extra housekeeping */ | |
286 | if (rw == WRITE) | |
287 | _about_to_complete_local_write(mdev, req); | |
288 | ||
289 | /* Update disk stats */ | |
290 | _drbd_end_io_acct(mdev, req); | |
291 | ||
292 | m->error = ok ? 0 : (error ?: -EIO); | |
293 | m->bio = req->master_bio; | |
294 | req->master_bio = NULL; | |
295 | } | |
296 | ||
297 | if ((s & RQ_NET_MASK) == 0 || (s & RQ_NET_DONE)) { | |
298 | /* this is disconnected (local only) operation, | |
299 | * or protocol C P_WRITE_ACK, | |
300 | * or protocol A or B P_BARRIER_ACK, | |
301 | * or killed from the transfer log due to connection loss. */ | |
302 | _req_is_done(mdev, req, rw); | |
303 | } | |
304 | /* else: network part and not DONE yet. that is | |
305 | * protocol A or B, barrier ack still pending... */ | |
306 | } | |
307 | ||
308 | /* | |
309 | * checks whether there was an overlapping request | |
310 | * or ee already registered. | |
311 | * | |
312 | * if so, return 1, in which case this request is completed on the spot, | |
313 | * without ever being submitted or send. | |
314 | * | |
315 | * return 0 if it is ok to submit this request. | |
316 | * | |
317 | * NOTE: | |
318 | * paranoia: assume something above us is broken, and issues different write | |
319 | * requests for the same block simultaneously... | |
320 | * | |
321 | * To ensure these won't be reordered differently on both nodes, resulting in | |
322 | * diverging data sets, we discard the later one(s). Not that this is supposed | |
323 | * to happen, but this is the rationale why we also have to check for | |
324 | * conflicting requests with local origin, and why we have to do so regardless | |
325 | * of whether we allowed multiple primaries. | |
326 | * | |
327 | * BTW, in case we only have one primary, the ee_hash is empty anyways, and the | |
328 | * second hlist_for_each_entry becomes a noop. This is even simpler than to | |
329 | * grab a reference on the net_conf, and check for the two_primaries flag... | |
330 | */ | |
331 | static int _req_conflicts(struct drbd_request *req) | |
332 | { | |
333 | struct drbd_conf *mdev = req->mdev; | |
334 | const sector_t sector = req->sector; | |
335 | const int size = req->size; | |
336 | struct drbd_request *i; | |
337 | struct drbd_epoch_entry *e; | |
338 | struct hlist_node *n; | |
339 | struct hlist_head *slot; | |
340 | ||
341 | D_ASSERT(hlist_unhashed(&req->colision)); | |
342 | ||
343 | if (!get_net_conf(mdev)) | |
344 | return 0; | |
345 | ||
346 | /* BUG_ON */ | |
347 | ERR_IF (mdev->tl_hash_s == 0) | |
348 | goto out_no_conflict; | |
349 | BUG_ON(mdev->tl_hash == NULL); | |
350 | ||
351 | #define OVERLAPS overlaps(i->sector, i->size, sector, size) | |
352 | slot = tl_hash_slot(mdev, sector); | |
353 | hlist_for_each_entry(i, n, slot, colision) { | |
354 | if (OVERLAPS) { | |
355 | dev_alert(DEV, "%s[%u] Concurrent local write detected! " | |
356 | "[DISCARD L] new: %llus +%u; " | |
357 | "pending: %llus +%u\n", | |
358 | current->comm, current->pid, | |
359 | (unsigned long long)sector, size, | |
360 | (unsigned long long)i->sector, i->size); | |
361 | goto out_conflict; | |
362 | } | |
363 | } | |
364 | ||
365 | if (mdev->ee_hash_s) { | |
366 | /* now, check for overlapping requests with remote origin */ | |
367 | BUG_ON(mdev->ee_hash == NULL); | |
368 | #undef OVERLAPS | |
369 | #define OVERLAPS overlaps(e->sector, e->size, sector, size) | |
370 | slot = ee_hash_slot(mdev, sector); | |
371 | hlist_for_each_entry(e, n, slot, colision) { | |
372 | if (OVERLAPS) { | |
373 | dev_alert(DEV, "%s[%u] Concurrent remote write detected!" | |
374 | " [DISCARD L] new: %llus +%u; " | |
375 | "pending: %llus +%u\n", | |
376 | current->comm, current->pid, | |
377 | (unsigned long long)sector, size, | |
378 | (unsigned long long)e->sector, e->size); | |
379 | goto out_conflict; | |
380 | } | |
381 | } | |
382 | } | |
383 | #undef OVERLAPS | |
384 | ||
385 | out_no_conflict: | |
386 | /* this is like it should be, and what we expected. | |
387 | * our users do behave after all... */ | |
388 | put_net_conf(mdev); | |
389 | return 0; | |
390 | ||
391 | out_conflict: | |
392 | put_net_conf(mdev); | |
393 | return 1; | |
394 | } | |
395 | ||
396 | /* obviously this could be coded as many single functions | |
397 | * instead of one huge switch, | |
398 | * or by putting the code directly in the respective locations | |
399 | * (as it has been before). | |
400 | * | |
401 | * but having it this way | |
402 | * enforces that it is all in this one place, where it is easier to audit, | |
403 | * it makes it obvious that whatever "event" "happens" to a request should | |
404 | * happen "atomically" within the req_lock, | |
405 | * and it enforces that we have to think in a very structured manner | |
406 | * about the "events" that may happen to a request during its life time ... | |
407 | */ | |
408 | void __req_mod(struct drbd_request *req, enum drbd_req_event what, | |
409 | struct bio_and_error *m) | |
410 | { | |
411 | struct drbd_conf *mdev = req->mdev; | |
412 | m->bio = NULL; | |
413 | ||
b411b363 PR |
414 | switch (what) { |
415 | default: | |
416 | dev_err(DEV, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__); | |
417 | break; | |
418 | ||
419 | /* does not happen... | |
420 | * initialization done in drbd_req_new | |
421 | case created: | |
422 | break; | |
423 | */ | |
424 | ||
425 | case to_be_send: /* via network */ | |
426 | /* reached via drbd_make_request_common | |
427 | * and from w_read_retry_remote */ | |
428 | D_ASSERT(!(req->rq_state & RQ_NET_MASK)); | |
429 | req->rq_state |= RQ_NET_PENDING; | |
430 | inc_ap_pending(mdev); | |
431 | break; | |
432 | ||
433 | case to_be_submitted: /* locally */ | |
434 | /* reached via drbd_make_request_common */ | |
435 | D_ASSERT(!(req->rq_state & RQ_LOCAL_MASK)); | |
436 | req->rq_state |= RQ_LOCAL_PENDING; | |
437 | break; | |
438 | ||
439 | case completed_ok: | |
440 | if (bio_data_dir(req->master_bio) == WRITE) | |
441 | mdev->writ_cnt += req->size>>9; | |
442 | else | |
443 | mdev->read_cnt += req->size>>9; | |
444 | ||
445 | req->rq_state |= (RQ_LOCAL_COMPLETED|RQ_LOCAL_OK); | |
446 | req->rq_state &= ~RQ_LOCAL_PENDING; | |
447 | ||
448 | _req_may_be_done(req, m); | |
449 | put_ldev(mdev); | |
450 | break; | |
451 | ||
452 | case write_completed_with_error: | |
453 | req->rq_state |= RQ_LOCAL_COMPLETED; | |
454 | req->rq_state &= ~RQ_LOCAL_PENDING; | |
455 | ||
456 | dev_alert(DEV, "Local WRITE failed sec=%llus size=%u\n", | |
457 | (unsigned long long)req->sector, req->size); | |
458 | /* and now: check how to handle local io error. */ | |
459 | __drbd_chk_io_error(mdev, FALSE); | |
460 | _req_may_be_done(req, m); | |
461 | put_ldev(mdev); | |
462 | break; | |
463 | ||
464 | case read_ahead_completed_with_error: | |
465 | /* it is legal to fail READA */ | |
466 | req->rq_state |= RQ_LOCAL_COMPLETED; | |
467 | req->rq_state &= ~RQ_LOCAL_PENDING; | |
468 | _req_may_be_done(req, m); | |
469 | put_ldev(mdev); | |
470 | break; | |
471 | ||
472 | case read_completed_with_error: | |
473 | drbd_set_out_of_sync(mdev, req->sector, req->size); | |
474 | ||
475 | req->rq_state |= RQ_LOCAL_COMPLETED; | |
476 | req->rq_state &= ~RQ_LOCAL_PENDING; | |
477 | ||
478 | dev_alert(DEV, "Local READ failed sec=%llus size=%u\n", | |
479 | (unsigned long long)req->sector, req->size); | |
480 | /* _req_mod(req,to_be_send); oops, recursion... */ | |
481 | D_ASSERT(!(req->rq_state & RQ_NET_MASK)); | |
482 | req->rq_state |= RQ_NET_PENDING; | |
483 | inc_ap_pending(mdev); | |
484 | ||
485 | __drbd_chk_io_error(mdev, FALSE); | |
486 | put_ldev(mdev); | |
487 | /* NOTE: if we have no connection, | |
488 | * or know the peer has no good data either, | |
489 | * then we don't actually need to "queue_for_net_read", | |
490 | * but we do so anyways, since the drbd_io_error() | |
491 | * and the potential state change to "Diskless" | |
492 | * needs to be done from process context */ | |
493 | ||
494 | /* fall through: _req_mod(req,queue_for_net_read); */ | |
495 | ||
496 | case queue_for_net_read: | |
497 | /* READ or READA, and | |
498 | * no local disk, | |
499 | * or target area marked as invalid, | |
500 | * or just got an io-error. */ | |
501 | /* from drbd_make_request_common | |
502 | * or from bio_endio during read io-error recovery */ | |
503 | ||
504 | /* so we can verify the handle in the answer packet | |
505 | * corresponding hlist_del is in _req_may_be_done() */ | |
506 | hlist_add_head(&req->colision, ar_hash_slot(mdev, req->sector)); | |
507 | ||
83c38830 | 508 | set_bit(UNPLUG_REMOTE, &mdev->flags); |
b411b363 PR |
509 | |
510 | D_ASSERT(req->rq_state & RQ_NET_PENDING); | |
511 | req->rq_state |= RQ_NET_QUEUED; | |
512 | req->w.cb = (req->rq_state & RQ_LOCAL_MASK) | |
513 | ? w_read_retry_remote | |
514 | : w_send_read_req; | |
515 | drbd_queue_work(&mdev->data.work, &req->w); | |
516 | break; | |
517 | ||
518 | case queue_for_net_write: | |
519 | /* assert something? */ | |
520 | /* from drbd_make_request_common only */ | |
521 | ||
522 | hlist_add_head(&req->colision, tl_hash_slot(mdev, req->sector)); | |
523 | /* corresponding hlist_del is in _req_may_be_done() */ | |
524 | ||
525 | /* NOTE | |
526 | * In case the req ended up on the transfer log before being | |
527 | * queued on the worker, it could lead to this request being | |
528 | * missed during cleanup after connection loss. | |
529 | * So we have to do both operations here, | |
530 | * within the same lock that protects the transfer log. | |
531 | * | |
532 | * _req_add_to_epoch(req); this has to be after the | |
533 | * _maybe_start_new_epoch(req); which happened in | |
534 | * drbd_make_request_common, because we now may set the bit | |
535 | * again ourselves to close the current epoch. | |
536 | * | |
537 | * Add req to the (now) current epoch (barrier). */ | |
538 | ||
83c38830 LE |
539 | /* otherwise we may lose an unplug, which may cause some remote |
540 | * io-scheduler timeout to expire, increasing maximum latency, | |
541 | * hurting performance. */ | |
542 | set_bit(UNPLUG_REMOTE, &mdev->flags); | |
543 | ||
b411b363 PR |
544 | /* see drbd_make_request_common, |
545 | * just after it grabs the req_lock */ | |
546 | D_ASSERT(test_bit(CREATE_BARRIER, &mdev->flags) == 0); | |
547 | ||
548 | req->epoch = mdev->newest_tle->br_number; | |
549 | list_add_tail(&req->tl_requests, | |
550 | &mdev->newest_tle->requests); | |
551 | ||
552 | /* increment size of current epoch */ | |
553 | mdev->newest_tle->n_req++; | |
554 | ||
555 | /* queue work item to send data */ | |
556 | D_ASSERT(req->rq_state & RQ_NET_PENDING); | |
557 | req->rq_state |= RQ_NET_QUEUED; | |
558 | req->w.cb = w_send_dblock; | |
559 | drbd_queue_work(&mdev->data.work, &req->w); | |
560 | ||
561 | /* close the epoch, in case it outgrew the limit */ | |
562 | if (mdev->newest_tle->n_req >= mdev->net_conf->max_epoch_size) | |
563 | queue_barrier(mdev); | |
564 | ||
565 | break; | |
566 | ||
567 | case send_canceled: | |
568 | /* treat it the same */ | |
569 | case send_failed: | |
570 | /* real cleanup will be done from tl_clear. just update flags | |
571 | * so it is no longer marked as on the worker queue */ | |
572 | req->rq_state &= ~RQ_NET_QUEUED; | |
573 | /* if we did it right, tl_clear should be scheduled only after | |
574 | * this, so this should not be necessary! */ | |
575 | _req_may_be_done(req, m); | |
576 | break; | |
577 | ||
578 | case handed_over_to_network: | |
579 | /* assert something? */ | |
580 | if (bio_data_dir(req->master_bio) == WRITE && | |
581 | mdev->net_conf->wire_protocol == DRBD_PROT_A) { | |
582 | /* this is what is dangerous about protocol A: | |
583 | * pretend it was successfully written on the peer. */ | |
584 | if (req->rq_state & RQ_NET_PENDING) { | |
585 | dec_ap_pending(mdev); | |
586 | req->rq_state &= ~RQ_NET_PENDING; | |
587 | req->rq_state |= RQ_NET_OK; | |
588 | } /* else: neg-ack was faster... */ | |
589 | /* it is still not yet RQ_NET_DONE until the | |
590 | * corresponding epoch barrier got acked as well, | |
591 | * so we know what to dirty on connection loss */ | |
592 | } | |
593 | req->rq_state &= ~RQ_NET_QUEUED; | |
594 | req->rq_state |= RQ_NET_SENT; | |
595 | /* because _drbd_send_zc_bio could sleep, and may want to | |
596 | * dereference the bio even after the "write_acked_by_peer" and | |
597 | * "completed_ok" events came in, once we return from | |
598 | * _drbd_send_zc_bio (drbd_send_dblock), we have to check | |
599 | * whether it is done already, and end it. */ | |
600 | _req_may_be_done(req, m); | |
601 | break; | |
602 | ||
603 | case connection_lost_while_pending: | |
604 | /* transfer log cleanup after connection loss */ | |
605 | /* assert something? */ | |
606 | if (req->rq_state & RQ_NET_PENDING) | |
607 | dec_ap_pending(mdev); | |
608 | req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING); | |
609 | req->rq_state |= RQ_NET_DONE; | |
610 | /* if it is still queued, we may not complete it here. | |
611 | * it will be canceled soon. */ | |
612 | if (!(req->rq_state & RQ_NET_QUEUED)) | |
613 | _req_may_be_done(req, m); | |
614 | break; | |
615 | ||
616 | case write_acked_by_peer_and_sis: | |
617 | req->rq_state |= RQ_NET_SIS; | |
618 | case conflict_discarded_by_peer: | |
619 | /* for discarded conflicting writes of multiple primaries, | |
620 | * there is no need to keep anything in the tl, potential | |
621 | * node crashes are covered by the activity log. */ | |
622 | if (what == conflict_discarded_by_peer) | |
623 | dev_alert(DEV, "Got DiscardAck packet %llus +%u!" | |
624 | " DRBD is not a random data generator!\n", | |
625 | (unsigned long long)req->sector, req->size); | |
626 | req->rq_state |= RQ_NET_DONE; | |
627 | /* fall through */ | |
628 | case write_acked_by_peer: | |
629 | /* protocol C; successfully written on peer. | |
630 | * Nothing to do here. | |
631 | * We want to keep the tl in place for all protocols, to cater | |
632 | * for volatile write-back caches on lower level devices. | |
633 | * | |
634 | * A barrier request is expected to have forced all prior | |
635 | * requests onto stable storage, so completion of a barrier | |
636 | * request could set NET_DONE right here, and not wait for the | |
637 | * P_BARRIER_ACK, but that is an unnecessary optimization. */ | |
638 | ||
639 | /* this makes it effectively the same as for: */ | |
640 | case recv_acked_by_peer: | |
641 | /* protocol B; pretends to be successfully written on peer. | |
642 | * see also notes above in handed_over_to_network about | |
643 | * protocol != C */ | |
644 | req->rq_state |= RQ_NET_OK; | |
645 | D_ASSERT(req->rq_state & RQ_NET_PENDING); | |
646 | dec_ap_pending(mdev); | |
647 | req->rq_state &= ~RQ_NET_PENDING; | |
648 | _req_may_be_done(req, m); | |
649 | break; | |
650 | ||
651 | case neg_acked: | |
652 | /* assert something? */ | |
653 | if (req->rq_state & RQ_NET_PENDING) | |
654 | dec_ap_pending(mdev); | |
655 | req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING); | |
656 | ||
657 | req->rq_state |= RQ_NET_DONE; | |
658 | _req_may_be_done(req, m); | |
659 | /* else: done by handed_over_to_network */ | |
660 | break; | |
661 | ||
662 | case barrier_acked: | |
663 | if (req->rq_state & RQ_NET_PENDING) { | |
664 | /* barrier came in before all requests have been acked. | |
665 | * this is bad, because if the connection is lost now, | |
666 | * we won't be able to clean them up... */ | |
667 | dev_err(DEV, "FIXME (barrier_acked but pending)\n"); | |
b411b363 PR |
668 | list_move(&req->tl_requests, &mdev->out_of_sequence_requests); |
669 | } | |
670 | D_ASSERT(req->rq_state & RQ_NET_SENT); | |
671 | req->rq_state |= RQ_NET_DONE; | |
672 | _req_may_be_done(req, m); | |
673 | break; | |
674 | ||
675 | case data_received: | |
676 | D_ASSERT(req->rq_state & RQ_NET_PENDING); | |
677 | dec_ap_pending(mdev); | |
678 | req->rq_state &= ~RQ_NET_PENDING; | |
679 | req->rq_state |= (RQ_NET_OK|RQ_NET_DONE); | |
680 | _req_may_be_done(req, m); | |
681 | break; | |
682 | }; | |
683 | } | |
684 | ||
685 | /* we may do a local read if: | |
686 | * - we are consistent (of course), | |
687 | * - or we are generally inconsistent, | |
688 | * BUT we are still/already IN SYNC for this area. | |
689 | * since size may be bigger than BM_BLOCK_SIZE, | |
690 | * we may need to check several bits. | |
691 | */ | |
692 | static int drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size) | |
693 | { | |
694 | unsigned long sbnr, ebnr; | |
695 | sector_t esector, nr_sectors; | |
696 | ||
697 | if (mdev->state.disk == D_UP_TO_DATE) | |
698 | return 1; | |
699 | if (mdev->state.disk >= D_OUTDATED) | |
700 | return 0; | |
701 | if (mdev->state.disk < D_INCONSISTENT) | |
702 | return 0; | |
703 | /* state.disk == D_INCONSISTENT We will have a look at the BitMap */ | |
704 | nr_sectors = drbd_get_capacity(mdev->this_bdev); | |
705 | esector = sector + (size >> 9) - 1; | |
706 | ||
707 | D_ASSERT(sector < nr_sectors); | |
708 | D_ASSERT(esector < nr_sectors); | |
709 | ||
710 | sbnr = BM_SECT_TO_BIT(sector); | |
711 | ebnr = BM_SECT_TO_BIT(esector); | |
712 | ||
713 | return 0 == drbd_bm_count_bits(mdev, sbnr, ebnr); | |
714 | } | |
715 | ||
716 | static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio) | |
717 | { | |
718 | const int rw = bio_rw(bio); | |
719 | const int size = bio->bi_size; | |
720 | const sector_t sector = bio->bi_sector; | |
721 | struct drbd_tl_epoch *b = NULL; | |
722 | struct drbd_request *req; | |
723 | int local, remote; | |
724 | int err = -EIO; | |
725 | ||
726 | /* allocate outside of all locks; */ | |
727 | req = drbd_req_new(mdev, bio); | |
728 | if (!req) { | |
729 | dec_ap_bio(mdev); | |
730 | /* only pass the error to the upper layers. | |
731 | * if user cannot handle io errors, that's not our business. */ | |
732 | dev_err(DEV, "could not kmalloc() req\n"); | |
733 | bio_endio(bio, -ENOMEM); | |
734 | return 0; | |
735 | } | |
736 | ||
b411b363 PR |
737 | local = get_ldev(mdev); |
738 | if (!local) { | |
739 | bio_put(req->private_bio); /* or we get a bio leak */ | |
740 | req->private_bio = NULL; | |
741 | } | |
742 | if (rw == WRITE) { | |
743 | remote = 1; | |
744 | } else { | |
745 | /* READ || READA */ | |
746 | if (local) { | |
747 | if (!drbd_may_do_local_read(mdev, sector, size)) { | |
748 | /* we could kick the syncer to | |
749 | * sync this extent asap, wait for | |
750 | * it, then continue locally. | |
751 | * Or just issue the request remotely. | |
752 | */ | |
753 | local = 0; | |
754 | bio_put(req->private_bio); | |
755 | req->private_bio = NULL; | |
756 | put_ldev(mdev); | |
757 | } | |
758 | } | |
759 | remote = !local && mdev->state.pdsk >= D_UP_TO_DATE; | |
760 | } | |
761 | ||
762 | /* If we have a disk, but a READA request is mapped to remote, | |
763 | * we are R_PRIMARY, D_INCONSISTENT, SyncTarget. | |
764 | * Just fail that READA request right here. | |
765 | * | |
766 | * THINK: maybe fail all READA when not local? | |
767 | * or make this configurable... | |
768 | * if network is slow, READA won't do any good. | |
769 | */ | |
770 | if (rw == READA && mdev->state.disk >= D_INCONSISTENT && !local) { | |
771 | err = -EWOULDBLOCK; | |
772 | goto fail_and_free_req; | |
773 | } | |
774 | ||
775 | /* For WRITES going to the local disk, grab a reference on the target | |
776 | * extent. This waits for any resync activity in the corresponding | |
777 | * resync extent to finish, and, if necessary, pulls in the target | |
778 | * extent into the activity log, which involves further disk io because | |
779 | * of transactional on-disk meta data updates. */ | |
780 | if (rw == WRITE && local) | |
781 | drbd_al_begin_io(mdev, sector); | |
782 | ||
783 | remote = remote && (mdev->state.pdsk == D_UP_TO_DATE || | |
784 | (mdev->state.pdsk == D_INCONSISTENT && | |
785 | mdev->state.conn >= C_CONNECTED)); | |
786 | ||
787 | if (!(local || remote)) { | |
788 | dev_err(DEV, "IO ERROR: neither local nor remote disk\n"); | |
789 | goto fail_free_complete; | |
790 | } | |
791 | ||
792 | /* For WRITE request, we have to make sure that we have an | |
793 | * unused_spare_tle, in case we need to start a new epoch. | |
794 | * I try to be smart and avoid to pre-allocate always "just in case", | |
795 | * but there is a race between testing the bit and pointer outside the | |
796 | * spinlock, and grabbing the spinlock. | |
797 | * if we lost that race, we retry. */ | |
798 | if (rw == WRITE && remote && | |
799 | mdev->unused_spare_tle == NULL && | |
800 | test_bit(CREATE_BARRIER, &mdev->flags)) { | |
801 | allocate_barrier: | |
802 | b = kmalloc(sizeof(struct drbd_tl_epoch), GFP_NOIO); | |
803 | if (!b) { | |
804 | dev_err(DEV, "Failed to alloc barrier.\n"); | |
805 | err = -ENOMEM; | |
806 | goto fail_free_complete; | |
807 | } | |
808 | } | |
809 | ||
810 | /* GOOD, everything prepared, grab the spin_lock */ | |
811 | spin_lock_irq(&mdev->req_lock); | |
812 | ||
813 | if (remote) { | |
814 | remote = (mdev->state.pdsk == D_UP_TO_DATE || | |
815 | (mdev->state.pdsk == D_INCONSISTENT && | |
816 | mdev->state.conn >= C_CONNECTED)); | |
817 | if (!remote) | |
818 | dev_warn(DEV, "lost connection while grabbing the req_lock!\n"); | |
819 | if (!(local || remote)) { | |
820 | dev_err(DEV, "IO ERROR: neither local nor remote disk\n"); | |
821 | spin_unlock_irq(&mdev->req_lock); | |
822 | goto fail_free_complete; | |
823 | } | |
824 | } | |
825 | ||
826 | if (b && mdev->unused_spare_tle == NULL) { | |
827 | mdev->unused_spare_tle = b; | |
828 | b = NULL; | |
829 | } | |
830 | if (rw == WRITE && remote && | |
831 | mdev->unused_spare_tle == NULL && | |
832 | test_bit(CREATE_BARRIER, &mdev->flags)) { | |
833 | /* someone closed the current epoch | |
834 | * while we were grabbing the spinlock */ | |
835 | spin_unlock_irq(&mdev->req_lock); | |
836 | goto allocate_barrier; | |
837 | } | |
838 | ||
839 | ||
840 | /* Update disk stats */ | |
841 | _drbd_start_io_acct(mdev, req, bio); | |
842 | ||
843 | /* _maybe_start_new_epoch(mdev); | |
844 | * If we need to generate a write barrier packet, we have to add the | |
845 | * new epoch (barrier) object, and queue the barrier packet for sending, | |
846 | * and queue the req's data after it _within the same lock_, otherwise | |
847 | * we have race conditions were the reorder domains could be mixed up. | |
848 | * | |
849 | * Even read requests may start a new epoch and queue the corresponding | |
850 | * barrier packet. To get the write ordering right, we only have to | |
851 | * make sure that, if this is a write request and it triggered a | |
852 | * barrier packet, this request is queued within the same spinlock. */ | |
853 | if (remote && mdev->unused_spare_tle && | |
854 | test_and_clear_bit(CREATE_BARRIER, &mdev->flags)) { | |
855 | _tl_add_barrier(mdev, mdev->unused_spare_tle); | |
856 | mdev->unused_spare_tle = NULL; | |
857 | } else { | |
858 | D_ASSERT(!(remote && rw == WRITE && | |
859 | test_bit(CREATE_BARRIER, &mdev->flags))); | |
860 | } | |
861 | ||
862 | /* NOTE | |
863 | * Actually, 'local' may be wrong here already, since we may have failed | |
864 | * to write to the meta data, and may become wrong anytime because of | |
865 | * local io-error for some other request, which would lead to us | |
866 | * "detaching" the local disk. | |
867 | * | |
868 | * 'remote' may become wrong any time because the network could fail. | |
869 | * | |
870 | * This is a harmless race condition, though, since it is handled | |
871 | * correctly at the appropriate places; so it just defers the failure | |
872 | * of the respective operation. | |
873 | */ | |
874 | ||
875 | /* mark them early for readability. | |
876 | * this just sets some state flags. */ | |
877 | if (remote) | |
878 | _req_mod(req, to_be_send); | |
879 | if (local) | |
880 | _req_mod(req, to_be_submitted); | |
881 | ||
882 | /* check this request on the collision detection hash tables. | |
883 | * if we have a conflict, just complete it here. | |
884 | * THINK do we want to check reads, too? (I don't think so...) */ | |
885 | if (rw == WRITE && _req_conflicts(req)) { | |
886 | /* this is a conflicting request. | |
887 | * even though it may have been only _partially_ | |
888 | * overlapping with one of the currently pending requests, | |
889 | * without even submitting or sending it, we will | |
890 | * pretend that it was successfully served right now. | |
891 | */ | |
892 | if (local) { | |
893 | bio_put(req->private_bio); | |
894 | req->private_bio = NULL; | |
895 | drbd_al_complete_io(mdev, req->sector); | |
896 | put_ldev(mdev); | |
897 | local = 0; | |
898 | } | |
899 | if (remote) | |
900 | dec_ap_pending(mdev); | |
901 | _drbd_end_io_acct(mdev, req); | |
902 | /* THINK: do we want to fail it (-EIO), or pretend success? */ | |
903 | bio_endio(req->master_bio, 0); | |
904 | req->master_bio = NULL; | |
905 | dec_ap_bio(mdev); | |
906 | drbd_req_free(req); | |
907 | remote = 0; | |
908 | } | |
909 | ||
910 | /* NOTE remote first: to get the concurrent write detection right, | |
911 | * we must register the request before start of local IO. */ | |
912 | if (remote) { | |
913 | /* either WRITE and C_CONNECTED, | |
914 | * or READ, and no local disk, | |
915 | * or READ, but not in sync. | |
916 | */ | |
917 | _req_mod(req, (rw == WRITE) | |
918 | ? queue_for_net_write | |
919 | : queue_for_net_read); | |
920 | } | |
921 | spin_unlock_irq(&mdev->req_lock); | |
922 | kfree(b); /* if someone else has beaten us to it... */ | |
923 | ||
924 | if (local) { | |
925 | req->private_bio->bi_bdev = mdev->ldev->backing_bdev; | |
926 | ||
b411b363 PR |
927 | if (FAULT_ACTIVE(mdev, rw == WRITE ? DRBD_FAULT_DT_WR |
928 | : rw == READ ? DRBD_FAULT_DT_RD | |
929 | : DRBD_FAULT_DT_RA)) | |
930 | bio_endio(req->private_bio, -EIO); | |
931 | else | |
932 | generic_make_request(req->private_bio); | |
933 | } | |
934 | ||
935 | /* we need to plug ALWAYS since we possibly need to kick lo_dev. | |
936 | * we plug after submit, so we won't miss an unplug event */ | |
937 | drbd_plug_device(mdev); | |
938 | ||
939 | return 0; | |
940 | ||
941 | fail_free_complete: | |
942 | if (rw == WRITE && local) | |
943 | drbd_al_complete_io(mdev, sector); | |
944 | fail_and_free_req: | |
945 | if (local) { | |
946 | bio_put(req->private_bio); | |
947 | req->private_bio = NULL; | |
948 | put_ldev(mdev); | |
949 | } | |
950 | bio_endio(bio, err); | |
951 | drbd_req_free(req); | |
952 | dec_ap_bio(mdev); | |
953 | kfree(b); | |
954 | ||
955 | return 0; | |
956 | } | |
957 | ||
958 | /* helper function for drbd_make_request | |
959 | * if we can determine just by the mdev (state) that this request will fail, | |
960 | * return 1 | |
961 | * otherwise return 0 | |
962 | */ | |
963 | static int drbd_fail_request_early(struct drbd_conf *mdev, int is_write) | |
964 | { | |
b411b363 PR |
965 | if (mdev->state.role != R_PRIMARY && |
966 | (!allow_oos || is_write)) { | |
967 | if (__ratelimit(&drbd_ratelimit_state)) { | |
968 | dev_err(DEV, "Process %s[%u] tried to %s; " | |
969 | "since we are not in Primary state, " | |
970 | "we cannot allow this\n", | |
971 | current->comm, current->pid, | |
972 | is_write ? "WRITE" : "READ"); | |
973 | } | |
974 | return 1; | |
975 | } | |
976 | ||
977 | /* | |
978 | * Paranoia: we might have been primary, but sync target, or | |
979 | * even diskless, then lost the connection. | |
980 | * This should have been handled (panic? suspend?) somewhere | |
981 | * else. But maybe it was not, so check again here. | |
982 | * Caution: as long as we do not have a read/write lock on mdev, | |
983 | * to serialize state changes, this is racy, since we may lose | |
984 | * the connection *after* we test for the cstate. | |
985 | */ | |
986 | if (mdev->state.disk < D_UP_TO_DATE && mdev->state.pdsk < D_UP_TO_DATE) { | |
987 | if (__ratelimit(&drbd_ratelimit_state)) | |
988 | dev_err(DEV, "Sorry, I have no access to good data anymore.\n"); | |
989 | return 1; | |
990 | } | |
991 | ||
992 | return 0; | |
993 | } | |
994 | ||
995 | int drbd_make_request_26(struct request_queue *q, struct bio *bio) | |
996 | { | |
997 | unsigned int s_enr, e_enr; | |
998 | struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata; | |
999 | ||
1000 | if (drbd_fail_request_early(mdev, bio_data_dir(bio) & WRITE)) { | |
1001 | bio_endio(bio, -EPERM); | |
1002 | return 0; | |
1003 | } | |
1004 | ||
1005 | /* Reject barrier requests if we know the underlying device does | |
1006 | * not support them. | |
1007 | * XXX: Need to get this info from peer as well some how so we | |
1008 | * XXX: reject if EITHER side/data/metadata area does not support them. | |
1009 | * | |
1010 | * because of those XXX, this is not yet enabled, | |
1011 | * i.e. in drbd_init_set_defaults we set the NO_BARRIER_SUPP bit. | |
1012 | */ | |
1013 | if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER) && test_bit(NO_BARRIER_SUPP, &mdev->flags))) { | |
1014 | /* dev_warn(DEV, "Rejecting barrier request as underlying device does not support\n"); */ | |
1015 | bio_endio(bio, -EOPNOTSUPP); | |
1016 | return 0; | |
1017 | } | |
1018 | ||
1019 | /* | |
1020 | * what we "blindly" assume: | |
1021 | */ | |
1022 | D_ASSERT(bio->bi_size > 0); | |
1023 | D_ASSERT((bio->bi_size & 0x1ff) == 0); | |
1024 | D_ASSERT(bio->bi_idx == 0); | |
1025 | ||
1026 | /* to make some things easier, force alignment of requests within the | |
1027 | * granularity of our hash tables */ | |
1028 | s_enr = bio->bi_sector >> HT_SHIFT; | |
1029 | e_enr = (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT; | |
1030 | ||
1031 | if (likely(s_enr == e_enr)) { | |
1032 | inc_ap_bio(mdev, 1); | |
1033 | return drbd_make_request_common(mdev, bio); | |
1034 | } | |
1035 | ||
1036 | /* can this bio be split generically? | |
1037 | * Maybe add our own split-arbitrary-bios function. */ | |
1038 | if (bio->bi_vcnt != 1 || bio->bi_idx != 0 || bio->bi_size > DRBD_MAX_SEGMENT_SIZE) { | |
1039 | /* rather error out here than BUG in bio_split */ | |
1040 | dev_err(DEV, "bio would need to, but cannot, be split: " | |
1041 | "(vcnt=%u,idx=%u,size=%u,sector=%llu)\n", | |
1042 | bio->bi_vcnt, bio->bi_idx, bio->bi_size, | |
1043 | (unsigned long long)bio->bi_sector); | |
1044 | bio_endio(bio, -EINVAL); | |
1045 | } else { | |
1046 | /* This bio crosses some boundary, so we have to split it. */ | |
1047 | struct bio_pair *bp; | |
1048 | /* works for the "do not cross hash slot boundaries" case | |
1049 | * e.g. sector 262269, size 4096 | |
1050 | * s_enr = 262269 >> 6 = 4097 | |
1051 | * e_enr = (262269+8-1) >> 6 = 4098 | |
1052 | * HT_SHIFT = 6 | |
1053 | * sps = 64, mask = 63 | |
1054 | * first_sectors = 64 - (262269 & 63) = 3 | |
1055 | */ | |
1056 | const sector_t sect = bio->bi_sector; | |
1057 | const int sps = 1 << HT_SHIFT; /* sectors per slot */ | |
1058 | const int mask = sps - 1; | |
1059 | const sector_t first_sectors = sps - (sect & mask); | |
1060 | bp = bio_split(bio, | |
1061 | #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28) | |
1062 | bio_split_pool, | |
1063 | #endif | |
1064 | first_sectors); | |
1065 | ||
1066 | /* we need to get a "reference count" (ap_bio_cnt) | |
1067 | * to avoid races with the disconnect/reconnect/suspend code. | |
1068 | * In case we need to split the bio here, we need to get two references | |
1069 | * atomically, otherwise we might deadlock when trying to submit the | |
1070 | * second one! */ | |
1071 | inc_ap_bio(mdev, 2); | |
1072 | ||
1073 | D_ASSERT(e_enr == s_enr + 1); | |
1074 | ||
1075 | drbd_make_request_common(mdev, &bp->bio1); | |
1076 | drbd_make_request_common(mdev, &bp->bio2); | |
1077 | bio_pair_release(bp); | |
1078 | } | |
1079 | return 0; | |
1080 | } | |
1081 | ||
1082 | /* This is called by bio_add_page(). With this function we reduce | |
1083 | * the number of BIOs that span over multiple DRBD_MAX_SEGMENT_SIZEs | |
1084 | * units (was AL_EXTENTs). | |
1085 | * | |
1086 | * we do the calculation within the lower 32bit of the byte offsets, | |
1087 | * since we don't care for actual offset, but only check whether it | |
1088 | * would cross "activity log extent" boundaries. | |
1089 | * | |
1090 | * As long as the BIO is empty we have to allow at least one bvec, | |
1091 | * regardless of size and offset. so the resulting bio may still | |
1092 | * cross extent boundaries. those are dealt with (bio_split) in | |
1093 | * drbd_make_request_26. | |
1094 | */ | |
1095 | int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec) | |
1096 | { | |
1097 | struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata; | |
1098 | unsigned int bio_offset = | |
1099 | (unsigned int)bvm->bi_sector << 9; /* 32 bit */ | |
1100 | unsigned int bio_size = bvm->bi_size; | |
1101 | int limit, backing_limit; | |
1102 | ||
1103 | limit = DRBD_MAX_SEGMENT_SIZE | |
1104 | - ((bio_offset & (DRBD_MAX_SEGMENT_SIZE-1)) + bio_size); | |
1105 | if (limit < 0) | |
1106 | limit = 0; | |
1107 | if (bio_size == 0) { | |
1108 | if (limit <= bvec->bv_len) | |
1109 | limit = bvec->bv_len; | |
1110 | } else if (limit && get_ldev(mdev)) { | |
1111 | struct request_queue * const b = | |
1112 | mdev->ldev->backing_bdev->bd_disk->queue; | |
a1c88d0d | 1113 | if (b->merge_bvec_fn) { |
b411b363 PR |
1114 | backing_limit = b->merge_bvec_fn(b, bvm, bvec); |
1115 | limit = min(limit, backing_limit); | |
1116 | } | |
1117 | put_ldev(mdev); | |
1118 | } | |
1119 | return limit; | |
1120 | } |