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