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 static bool drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size); 35 36 /* Update disk stats at start of I/O request */ 37 static void _drbd_start_io_acct(struct drbd_conf *mdev, struct drbd_request *req, struct bio *bio) 38 { 39 const int rw = bio_data_dir(bio); 40 int cpu; 41 cpu = part_stat_lock(); 42 part_round_stats(cpu, &mdev->vdisk->part0); 43 part_stat_inc(cpu, &mdev->vdisk->part0, ios[rw]); 44 part_stat_add(cpu, &mdev->vdisk->part0, sectors[rw], bio_sectors(bio)); 45 (void) cpu; /* The macro invocations above want the cpu argument, I do not like 46 the compiler warning about cpu only assigned but never used... */ 47 part_inc_in_flight(&mdev->vdisk->part0, rw); 48 part_stat_unlock(); 49 } 50 51 /* Update disk stats when completing request upwards */ 52 static void _drbd_end_io_acct(struct drbd_conf *mdev, struct drbd_request *req) 53 { 54 int rw = bio_data_dir(req->master_bio); 55 unsigned long duration = jiffies - req->start_time; 56 int cpu; 57 cpu = part_stat_lock(); 58 part_stat_add(cpu, &mdev->vdisk->part0, ticks[rw], duration); 59 part_round_stats(cpu, &mdev->vdisk->part0); 60 part_dec_in_flight(&mdev->vdisk->part0, rw); 61 part_stat_unlock(); 62 } 63 64 static struct drbd_request *drbd_req_new(struct drbd_conf *mdev, 65 struct bio *bio_src) 66 { 67 struct drbd_request *req; 68 69 req = mempool_alloc(drbd_request_mempool, GFP_NOIO); 70 if (!req) 71 return NULL; 72 73 drbd_req_make_private_bio(req, bio_src); 74 req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0; 75 req->w.mdev = mdev; 76 req->master_bio = bio_src; 77 req->epoch = 0; 78 79 drbd_clear_interval(&req->i); 80 req->i.sector = bio_src->bi_sector; 81 req->i.size = bio_src->bi_size; 82 req->i.local = true; 83 req->i.waiting = false; 84 85 INIT_LIST_HEAD(&req->tl_requests); 86 INIT_LIST_HEAD(&req->w.list); 87 88 /* one reference to be put by __drbd_make_request */ 89 atomic_set(&req->completion_ref, 1); 90 /* one kref as long as completion_ref > 0 */ 91 kref_init(&req->kref); 92 return req; 93 } 94 95 void drbd_req_destroy(struct kref *kref) 96 { 97 struct drbd_request *req = container_of(kref, struct drbd_request, kref); 98 struct drbd_conf *mdev = req->w.mdev; 99 const unsigned s = req->rq_state; 100 101 if ((req->master_bio && !(s & RQ_POSTPONED)) || 102 atomic_read(&req->completion_ref) || 103 (s & RQ_LOCAL_PENDING) || 104 ((s & RQ_NET_MASK) && !(s & RQ_NET_DONE))) { 105 dev_err(DEV, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n", 106 s, atomic_read(&req->completion_ref)); 107 return; 108 } 109 110 /* remove it from the transfer log. 111 * well, only if it had been there in the first 112 * place... if it had not (local only or conflicting 113 * and never sent), it should still be "empty" as 114 * initialized in drbd_req_new(), so we can list_del() it 115 * here unconditionally */ 116 list_del_init(&req->tl_requests); 117 118 /* if it was a write, we may have to set the corresponding 119 * bit(s) out-of-sync first. If it had a local part, we need to 120 * release the reference to the activity log. */ 121 if (s & RQ_WRITE) { 122 /* Set out-of-sync unless both OK flags are set 123 * (local only or remote failed). 124 * Other places where we set out-of-sync: 125 * READ with local io-error */ 126 127 /* There is a special case: 128 * we may notice late that IO was suspended, 129 * and postpone, or schedule for retry, a write, 130 * before it even was submitted or sent. 131 * In that case we do not want to touch the bitmap at all. 132 */ 133 if ((s & (RQ_POSTPONED|RQ_LOCAL_MASK|RQ_NET_MASK)) != RQ_POSTPONED) { 134 if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK)) 135 drbd_set_out_of_sync(mdev, req->i.sector, req->i.size); 136 137 if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS)) 138 drbd_set_in_sync(mdev, req->i.sector, req->i.size); 139 } 140 141 /* one might be tempted to move the drbd_al_complete_io 142 * to the local io completion callback drbd_request_endio. 143 * but, if this was a mirror write, we may only 144 * drbd_al_complete_io after this is RQ_NET_DONE, 145 * otherwise the extent could be dropped from the al 146 * before it has actually been written on the peer. 147 * if we crash before our peer knows about the request, 148 * but after the extent has been dropped from the al, 149 * we would forget to resync the corresponding extent. 150 */ 151 if (s & RQ_IN_ACT_LOG) { 152 if (get_ldev_if_state(mdev, D_FAILED)) { 153 drbd_al_complete_io(mdev, &req->i); 154 put_ldev(mdev); 155 } else if (__ratelimit(&drbd_ratelimit_state)) { 156 dev_warn(DEV, "Should have called drbd_al_complete_io(, %llu, %u), " 157 "but my Disk seems to have failed :(\n", 158 (unsigned long long) req->i.sector, req->i.size); 159 } 160 } 161 } 162 163 mempool_free(req, drbd_request_mempool); 164 } 165 166 static void wake_all_senders(struct drbd_tconn *tconn) { 167 wake_up(&tconn->sender_work.q_wait); 168 } 169 170 /* must hold resource->req_lock */ 171 void start_new_tl_epoch(struct drbd_tconn *tconn) 172 { 173 /* no point closing an epoch, if it is empty, anyways. */ 174 if (tconn->current_tle_writes == 0) 175 return; 176 177 tconn->current_tle_writes = 0; 178 atomic_inc(&tconn->current_tle_nr); 179 wake_all_senders(tconn); 180 } 181 182 void complete_master_bio(struct drbd_conf *mdev, 183 struct bio_and_error *m) 184 { 185 bio_endio(m->bio, m->error); 186 dec_ap_bio(mdev); 187 } 188 189 190 static void drbd_remove_request_interval(struct rb_root *root, 191 struct drbd_request *req) 192 { 193 struct drbd_conf *mdev = req->w.mdev; 194 struct drbd_interval *i = &req->i; 195 196 drbd_remove_interval(root, i); 197 198 /* Wake up any processes waiting for this request to complete. */ 199 if (i->waiting) 200 wake_up(&mdev->misc_wait); 201 } 202 203 /* Helper for __req_mod(). 204 * Set m->bio to the master bio, if it is fit to be completed, 205 * or leave it alone (it is initialized to NULL in __req_mod), 206 * if it has already been completed, or cannot be completed yet. 207 * If m->bio is set, the error status to be returned is placed in m->error. 208 */ 209 static 210 void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m) 211 { 212 const unsigned s = req->rq_state; 213 struct drbd_conf *mdev = req->w.mdev; 214 int rw; 215 int error, ok; 216 217 /* we must not complete the master bio, while it is 218 * still being processed by _drbd_send_zc_bio (drbd_send_dblock) 219 * not yet acknowledged by the peer 220 * not yet completed by the local io subsystem 221 * these flags may get cleared in any order by 222 * the worker, 223 * the receiver, 224 * the bio_endio completion callbacks. 225 */ 226 if ((s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED)) || 227 (s & RQ_NET_QUEUED) || (s & RQ_NET_PENDING) || 228 (s & RQ_COMPLETION_SUSP)) { 229 dev_err(DEV, "drbd_req_complete: Logic BUG rq_state = 0x%x\n", s); 230 return; 231 } 232 233 if (!req->master_bio) { 234 dev_err(DEV, "drbd_req_complete: Logic BUG, master_bio == NULL!\n"); 235 return; 236 } 237 238 rw = bio_rw(req->master_bio); 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_request_endio. 252 */ 253 ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK); 254 error = PTR_ERR(req->private_bio); 255 256 /* remove the request from the conflict detection 257 * respective block_id verification hash */ 258 if (!drbd_interval_empty(&req->i)) { 259 struct rb_root *root; 260 261 if (rw == WRITE) 262 root = &mdev->write_requests; 263 else 264 root = &mdev->read_requests; 265 drbd_remove_request_interval(root, req); 266 } else if (!(s & RQ_POSTPONED)) 267 D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0); 268 269 /* Before we can signal completion to the upper layers, 270 * we may need to close the current transfer log epoch. 271 * We are within the request lock, so we can simply compare 272 * the request epoch number with the current transfer log 273 * epoch number. If they match, increase the current_tle_nr, 274 * and reset the transfer log epoch write_cnt. 275 */ 276 if (rw == WRITE && 277 req->epoch == atomic_read(&mdev->tconn->current_tle_nr)) 278 start_new_tl_epoch(mdev->tconn); 279 280 /* Update disk stats */ 281 _drbd_end_io_acct(mdev, req); 282 283 /* If READ failed, 284 * have it be pushed back to the retry work queue, 285 * so it will re-enter __drbd_make_request(), 286 * and be re-assigned to a suitable local or remote path, 287 * or failed if we do not have access to good data anymore. 288 * 289 * Unless it was failed early by __drbd_make_request(), 290 * because no path was available, in which case 291 * it was not even added to the transfer_log. 292 * 293 * READA may fail, and will not be retried. 294 * 295 * WRITE should have used all available paths already. 296 */ 297 if (!ok && rw == READ && !list_empty(&req->tl_requests)) 298 req->rq_state |= RQ_POSTPONED; 299 300 if (!(req->rq_state & RQ_POSTPONED)) { 301 m->error = ok ? 0 : (error ?: -EIO); 302 m->bio = req->master_bio; 303 req->master_bio = NULL; 304 } 305 } 306 307 static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put) 308 { 309 struct drbd_conf *mdev = req->w.mdev; 310 D_ASSERT(m || (req->rq_state & RQ_POSTPONED)); 311 312 if (!atomic_sub_and_test(put, &req->completion_ref)) 313 return 0; 314 315 drbd_req_complete(req, m); 316 317 if (req->rq_state & RQ_POSTPONED) { 318 /* don't destroy the req object just yet, 319 * but queue it for retry */ 320 drbd_restart_request(req); 321 return 0; 322 } 323 324 return 1; 325 } 326 327 /* I'd like this to be the only place that manipulates 328 * req->completion_ref and req->kref. */ 329 static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, 330 int clear, int set) 331 { 332 struct drbd_conf *mdev = req->w.mdev; 333 unsigned s = req->rq_state; 334 int c_put = 0; 335 int k_put = 0; 336 337 if (drbd_suspended(mdev) && !((s | clear) & RQ_COMPLETION_SUSP)) 338 set |= RQ_COMPLETION_SUSP; 339 340 /* apply */ 341 342 req->rq_state &= ~clear; 343 req->rq_state |= set; 344 345 /* no change? */ 346 if (req->rq_state == s) 347 return; 348 349 /* intent: get references */ 350 351 if (!(s & RQ_LOCAL_PENDING) && (set & RQ_LOCAL_PENDING)) 352 atomic_inc(&req->completion_ref); 353 354 if (!(s & RQ_NET_PENDING) && (set & RQ_NET_PENDING)) { 355 inc_ap_pending(mdev); 356 atomic_inc(&req->completion_ref); 357 } 358 359 if (!(s & RQ_NET_QUEUED) && (set & RQ_NET_QUEUED)) 360 atomic_inc(&req->completion_ref); 361 362 if (!(s & RQ_EXP_BARR_ACK) && (set & RQ_EXP_BARR_ACK)) 363 kref_get(&req->kref); /* wait for the DONE */ 364 365 if (!(s & RQ_NET_SENT) && (set & RQ_NET_SENT)) 366 atomic_add(req->i.size >> 9, &mdev->ap_in_flight); 367 368 if (!(s & RQ_COMPLETION_SUSP) && (set & RQ_COMPLETION_SUSP)) 369 atomic_inc(&req->completion_ref); 370 371 /* progress: put references */ 372 373 if ((s & RQ_COMPLETION_SUSP) && (clear & RQ_COMPLETION_SUSP)) 374 ++c_put; 375 376 if (!(s & RQ_LOCAL_ABORTED) && (set & RQ_LOCAL_ABORTED)) { 377 D_ASSERT(req->rq_state & RQ_LOCAL_PENDING); 378 /* local completion may still come in later, 379 * we need to keep the req object around. */ 380 kref_get(&req->kref); 381 ++c_put; 382 } 383 384 if ((s & RQ_LOCAL_PENDING) && (clear & RQ_LOCAL_PENDING)) { 385 if (req->rq_state & RQ_LOCAL_ABORTED) 386 ++k_put; 387 else 388 ++c_put; 389 } 390 391 if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) { 392 dec_ap_pending(mdev); 393 ++c_put; 394 } 395 396 if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED)) 397 ++c_put; 398 399 if ((s & RQ_EXP_BARR_ACK) && !(s & RQ_NET_DONE) && (set & RQ_NET_DONE)) { 400 if (req->rq_state & RQ_NET_SENT) 401 atomic_sub(req->i.size >> 9, &mdev->ap_in_flight); 402 ++k_put; 403 } 404 405 /* potentially complete and destroy */ 406 407 if (k_put || c_put) { 408 /* Completion does it's own kref_put. If we are going to 409 * kref_sub below, we need req to be still around then. */ 410 int at_least = k_put + !!c_put; 411 int refcount = atomic_read(&req->kref.refcount); 412 if (refcount < at_least) 413 dev_err(DEV, 414 "mod_rq_state: Logic BUG: %x -> %x: refcount = %d, should be >= %d\n", 415 s, req->rq_state, refcount, at_least); 416 } 417 418 /* If we made progress, retry conflicting peer requests, if any. */ 419 if (req->i.waiting) 420 wake_up(&mdev->misc_wait); 421 422 if (c_put) 423 k_put += drbd_req_put_completion_ref(req, m, c_put); 424 if (k_put) 425 kref_sub(&req->kref, k_put, drbd_req_destroy); 426 } 427 428 static void drbd_report_io_error(struct drbd_conf *mdev, struct drbd_request *req) 429 { 430 char b[BDEVNAME_SIZE]; 431 432 if (!__ratelimit(&drbd_ratelimit_state)) 433 return; 434 435 dev_warn(DEV, "local %s IO error sector %llu+%u on %s\n", 436 (req->rq_state & RQ_WRITE) ? "WRITE" : "READ", 437 (unsigned long long)req->i.sector, 438 req->i.size >> 9, 439 bdevname(mdev->ldev->backing_bdev, b)); 440 } 441 442 /* obviously this could be coded as many single functions 443 * instead of one huge switch, 444 * or by putting the code directly in the respective locations 445 * (as it has been before). 446 * 447 * but having it this way 448 * enforces that it is all in this one place, where it is easier to audit, 449 * it makes it obvious that whatever "event" "happens" to a request should 450 * happen "atomically" within the req_lock, 451 * and it enforces that we have to think in a very structured manner 452 * about the "events" that may happen to a request during its life time ... 453 */ 454 int __req_mod(struct drbd_request *req, enum drbd_req_event what, 455 struct bio_and_error *m) 456 { 457 struct drbd_conf *mdev = req->w.mdev; 458 struct net_conf *nc; 459 int p, rv = 0; 460 461 if (m) 462 m->bio = NULL; 463 464 switch (what) { 465 default: 466 dev_err(DEV, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__); 467 break; 468 469 /* does not happen... 470 * initialization done in drbd_req_new 471 case CREATED: 472 break; 473 */ 474 475 case TO_BE_SENT: /* via network */ 476 /* reached via __drbd_make_request 477 * and from w_read_retry_remote */ 478 D_ASSERT(!(req->rq_state & RQ_NET_MASK)); 479 rcu_read_lock(); 480 nc = rcu_dereference(mdev->tconn->net_conf); 481 p = nc->wire_protocol; 482 rcu_read_unlock(); 483 req->rq_state |= 484 p == DRBD_PROT_C ? RQ_EXP_WRITE_ACK : 485 p == DRBD_PROT_B ? RQ_EXP_RECEIVE_ACK : 0; 486 mod_rq_state(req, m, 0, RQ_NET_PENDING); 487 break; 488 489 case TO_BE_SUBMITTED: /* locally */ 490 /* reached via __drbd_make_request */ 491 D_ASSERT(!(req->rq_state & RQ_LOCAL_MASK)); 492 mod_rq_state(req, m, 0, RQ_LOCAL_PENDING); 493 break; 494 495 case COMPLETED_OK: 496 if (req->rq_state & RQ_WRITE) 497 mdev->writ_cnt += req->i.size >> 9; 498 else 499 mdev->read_cnt += req->i.size >> 9; 500 501 mod_rq_state(req, m, RQ_LOCAL_PENDING, 502 RQ_LOCAL_COMPLETED|RQ_LOCAL_OK); 503 break; 504 505 case ABORT_DISK_IO: 506 mod_rq_state(req, m, 0, RQ_LOCAL_ABORTED); 507 break; 508 509 case WRITE_COMPLETED_WITH_ERROR: 510 drbd_report_io_error(mdev, req); 511 __drbd_chk_io_error(mdev, DRBD_WRITE_ERROR); 512 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED); 513 break; 514 515 case READ_COMPLETED_WITH_ERROR: 516 drbd_set_out_of_sync(mdev, req->i.sector, req->i.size); 517 drbd_report_io_error(mdev, req); 518 __drbd_chk_io_error(mdev, DRBD_READ_ERROR); 519 /* fall through. */ 520 case READ_AHEAD_COMPLETED_WITH_ERROR: 521 /* it is legal to fail READA, no __drbd_chk_io_error in that case. */ 522 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED); 523 break; 524 525 case QUEUE_FOR_NET_READ: 526 /* READ or READA, and 527 * no local disk, 528 * or target area marked as invalid, 529 * or just got an io-error. */ 530 /* from __drbd_make_request 531 * or from bio_endio during read io-error recovery */ 532 533 /* So we can verify the handle in the answer packet. 534 * Corresponding drbd_remove_request_interval is in 535 * drbd_req_complete() */ 536 D_ASSERT(drbd_interval_empty(&req->i)); 537 drbd_insert_interval(&mdev->read_requests, &req->i); 538 539 set_bit(UNPLUG_REMOTE, &mdev->flags); 540 541 D_ASSERT(req->rq_state & RQ_NET_PENDING); 542 D_ASSERT((req->rq_state & RQ_LOCAL_MASK) == 0); 543 mod_rq_state(req, m, 0, RQ_NET_QUEUED); 544 req->w.cb = w_send_read_req; 545 drbd_queue_work(&mdev->tconn->sender_work, &req->w); 546 break; 547 548 case QUEUE_FOR_NET_WRITE: 549 /* assert something? */ 550 /* from __drbd_make_request only */ 551 552 /* Corresponding drbd_remove_request_interval is in 553 * drbd_req_complete() */ 554 D_ASSERT(drbd_interval_empty(&req->i)); 555 drbd_insert_interval(&mdev->write_requests, &req->i); 556 557 /* NOTE 558 * In case the req ended up on the transfer log before being 559 * queued on the worker, it could lead to this request being 560 * missed during cleanup after connection loss. 561 * So we have to do both operations here, 562 * within the same lock that protects the transfer log. 563 * 564 * _req_add_to_epoch(req); this has to be after the 565 * _maybe_start_new_epoch(req); which happened in 566 * __drbd_make_request, because we now may set the bit 567 * again ourselves to close the current epoch. 568 * 569 * Add req to the (now) current epoch (barrier). */ 570 571 /* otherwise we may lose an unplug, which may cause some remote 572 * io-scheduler timeout to expire, increasing maximum latency, 573 * hurting performance. */ 574 set_bit(UNPLUG_REMOTE, &mdev->flags); 575 576 /* queue work item to send data */ 577 D_ASSERT(req->rq_state & RQ_NET_PENDING); 578 mod_rq_state(req, m, 0, RQ_NET_QUEUED|RQ_EXP_BARR_ACK); 579 req->w.cb = w_send_dblock; 580 drbd_queue_work(&mdev->tconn->sender_work, &req->w); 581 582 /* close the epoch, in case it outgrew the limit */ 583 rcu_read_lock(); 584 nc = rcu_dereference(mdev->tconn->net_conf); 585 p = nc->max_epoch_size; 586 rcu_read_unlock(); 587 if (mdev->tconn->current_tle_writes >= p) 588 start_new_tl_epoch(mdev->tconn); 589 590 break; 591 592 case QUEUE_FOR_SEND_OOS: 593 mod_rq_state(req, m, 0, RQ_NET_QUEUED); 594 req->w.cb = w_send_out_of_sync; 595 drbd_queue_work(&mdev->tconn->sender_work, &req->w); 596 break; 597 598 case READ_RETRY_REMOTE_CANCELED: 599 case SEND_CANCELED: 600 case SEND_FAILED: 601 /* real cleanup will be done from tl_clear. just update flags 602 * so it is no longer marked as on the worker queue */ 603 mod_rq_state(req, m, RQ_NET_QUEUED, 0); 604 break; 605 606 case HANDED_OVER_TO_NETWORK: 607 /* assert something? */ 608 if (bio_data_dir(req->master_bio) == WRITE && 609 !(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK))) { 610 /* this is what is dangerous about protocol A: 611 * pretend it was successfully written on the peer. */ 612 if (req->rq_state & RQ_NET_PENDING) 613 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK); 614 /* else: neg-ack was faster... */ 615 /* it is still not yet RQ_NET_DONE until the 616 * corresponding epoch barrier got acked as well, 617 * so we know what to dirty on connection loss */ 618 } 619 mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_SENT); 620 break; 621 622 case OOS_HANDED_TO_NETWORK: 623 /* Was not set PENDING, no longer QUEUED, so is now DONE 624 * as far as this connection is concerned. */ 625 mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_DONE); 626 break; 627 628 case CONNECTION_LOST_WHILE_PENDING: 629 /* transfer log cleanup after connection loss */ 630 mod_rq_state(req, m, 631 RQ_NET_OK|RQ_NET_PENDING|RQ_COMPLETION_SUSP, 632 RQ_NET_DONE); 633 break; 634 635 case CONFLICT_RESOLVED: 636 /* for superseded conflicting writes of multiple primaries, 637 * there is no need to keep anything in the tl, potential 638 * node crashes are covered by the activity log. 639 * 640 * If this request had been marked as RQ_POSTPONED before, 641 * it will actually not be completed, but "restarted", 642 * resubmitted from the retry worker context. */ 643 D_ASSERT(req->rq_state & RQ_NET_PENDING); 644 D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK); 645 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_DONE|RQ_NET_OK); 646 break; 647 648 case WRITE_ACKED_BY_PEER_AND_SIS: 649 req->rq_state |= RQ_NET_SIS; 650 case WRITE_ACKED_BY_PEER: 651 D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK); 652 /* protocol C; successfully written on peer. 653 * Nothing more to do here. 654 * We want to keep the tl in place for all protocols, to cater 655 * for volatile write-back caches on lower level devices. */ 656 657 goto ack_common; 658 case RECV_ACKED_BY_PEER: 659 D_ASSERT(req->rq_state & RQ_EXP_RECEIVE_ACK); 660 /* protocol B; pretends to be successfully written on peer. 661 * see also notes above in HANDED_OVER_TO_NETWORK about 662 * protocol != C */ 663 ack_common: 664 D_ASSERT(req->rq_state & RQ_NET_PENDING); 665 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK); 666 break; 667 668 case POSTPONE_WRITE: 669 D_ASSERT(req->rq_state & RQ_EXP_WRITE_ACK); 670 /* If this node has already detected the write conflict, the 671 * worker will be waiting on misc_wait. Wake it up once this 672 * request has completed locally. 673 */ 674 D_ASSERT(req->rq_state & RQ_NET_PENDING); 675 req->rq_state |= RQ_POSTPONED; 676 if (req->i.waiting) 677 wake_up(&mdev->misc_wait); 678 /* Do not clear RQ_NET_PENDING. This request will make further 679 * progress via restart_conflicting_writes() or 680 * fail_postponed_requests(). Hopefully. */ 681 break; 682 683 case NEG_ACKED: 684 mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING, 0); 685 break; 686 687 case FAIL_FROZEN_DISK_IO: 688 if (!(req->rq_state & RQ_LOCAL_COMPLETED)) 689 break; 690 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0); 691 break; 692 693 case RESTART_FROZEN_DISK_IO: 694 if (!(req->rq_state & RQ_LOCAL_COMPLETED)) 695 break; 696 697 mod_rq_state(req, m, 698 RQ_COMPLETION_SUSP|RQ_LOCAL_COMPLETED, 699 RQ_LOCAL_PENDING); 700 701 rv = MR_READ; 702 if (bio_data_dir(req->master_bio) == WRITE) 703 rv = MR_WRITE; 704 705 get_ldev(mdev); /* always succeeds in this call path */ 706 req->w.cb = w_restart_disk_io; 707 drbd_queue_work(&mdev->tconn->sender_work, &req->w); 708 break; 709 710 case RESEND: 711 /* Simply complete (local only) READs. */ 712 if (!(req->rq_state & RQ_WRITE) && !req->w.cb) { 713 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0); 714 break; 715 } 716 717 /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK 718 before the connection loss (B&C only); only P_BARRIER_ACK 719 (or the local completion?) was missing when we suspended. 720 Throwing them out of the TL here by pretending we got a BARRIER_ACK. 721 During connection handshake, we ensure that the peer was not rebooted. */ 722 if (!(req->rq_state & RQ_NET_OK)) { 723 /* FIXME could this possibly be a req->w.cb == w_send_out_of_sync? 724 * in that case we must not set RQ_NET_PENDING. */ 725 726 mod_rq_state(req, m, RQ_COMPLETION_SUSP, RQ_NET_QUEUED|RQ_NET_PENDING); 727 if (req->w.cb) { 728 drbd_queue_work(&mdev->tconn->sender_work, &req->w); 729 rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ; 730 } /* else: FIXME can this happen? */ 731 break; 732 } 733 /* else, fall through to BARRIER_ACKED */ 734 735 case BARRIER_ACKED: 736 /* barrier ack for READ requests does not make sense */ 737 if (!(req->rq_state & RQ_WRITE)) 738 break; 739 740 if (req->rq_state & RQ_NET_PENDING) { 741 /* barrier came in before all requests were acked. 742 * this is bad, because if the connection is lost now, 743 * we won't be able to clean them up... */ 744 dev_err(DEV, "FIXME (BARRIER_ACKED but pending)\n"); 745 } 746 /* Allowed to complete requests, even while suspended. 747 * As this is called for all requests within a matching epoch, 748 * we need to filter, and only set RQ_NET_DONE for those that 749 * have actually been on the wire. */ 750 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 751 (req->rq_state & RQ_NET_MASK) ? RQ_NET_DONE : 0); 752 break; 753 754 case DATA_RECEIVED: 755 D_ASSERT(req->rq_state & RQ_NET_PENDING); 756 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK|RQ_NET_DONE); 757 break; 758 }; 759 760 return rv; 761 } 762 763 /* we may do a local read if: 764 * - we are consistent (of course), 765 * - or we are generally inconsistent, 766 * BUT we are still/already IN SYNC for this area. 767 * since size may be bigger than BM_BLOCK_SIZE, 768 * we may need to check several bits. 769 */ 770 static bool drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size) 771 { 772 unsigned long sbnr, ebnr; 773 sector_t esector, nr_sectors; 774 775 if (mdev->state.disk == D_UP_TO_DATE) 776 return true; 777 if (mdev->state.disk != D_INCONSISTENT) 778 return false; 779 esector = sector + (size >> 9) - 1; 780 nr_sectors = drbd_get_capacity(mdev->this_bdev); 781 D_ASSERT(sector < nr_sectors); 782 D_ASSERT(esector < nr_sectors); 783 784 sbnr = BM_SECT_TO_BIT(sector); 785 ebnr = BM_SECT_TO_BIT(esector); 786 787 return drbd_bm_count_bits(mdev, sbnr, ebnr) == 0; 788 } 789 790 static bool remote_due_to_read_balancing(struct drbd_conf *mdev, sector_t sector, 791 enum drbd_read_balancing rbm) 792 { 793 struct backing_dev_info *bdi; 794 int stripe_shift; 795 796 switch (rbm) { 797 case RB_CONGESTED_REMOTE: 798 bdi = &mdev->ldev->backing_bdev->bd_disk->queue->backing_dev_info; 799 return bdi_read_congested(bdi); 800 case RB_LEAST_PENDING: 801 return atomic_read(&mdev->local_cnt) > 802 atomic_read(&mdev->ap_pending_cnt) + atomic_read(&mdev->rs_pending_cnt); 803 case RB_32K_STRIPING: /* stripe_shift = 15 */ 804 case RB_64K_STRIPING: 805 case RB_128K_STRIPING: 806 case RB_256K_STRIPING: 807 case RB_512K_STRIPING: 808 case RB_1M_STRIPING: /* stripe_shift = 20 */ 809 stripe_shift = (rbm - RB_32K_STRIPING + 15); 810 return (sector >> (stripe_shift - 9)) & 1; 811 case RB_ROUND_ROBIN: 812 return test_and_change_bit(READ_BALANCE_RR, &mdev->flags); 813 case RB_PREFER_REMOTE: 814 return true; 815 case RB_PREFER_LOCAL: 816 default: 817 return false; 818 } 819 } 820 821 /* 822 * complete_conflicting_writes - wait for any conflicting write requests 823 * 824 * The write_requests tree contains all active write requests which we 825 * currently know about. Wait for any requests to complete which conflict with 826 * the new one. 827 * 828 * Only way out: remove the conflicting intervals from the tree. 829 */ 830 static void complete_conflicting_writes(struct drbd_request *req) 831 { 832 DEFINE_WAIT(wait); 833 struct drbd_conf *mdev = req->w.mdev; 834 struct drbd_interval *i; 835 sector_t sector = req->i.sector; 836 int size = req->i.size; 837 838 i = drbd_find_overlap(&mdev->write_requests, sector, size); 839 if (!i) 840 return; 841 842 for (;;) { 843 prepare_to_wait(&mdev->misc_wait, &wait, TASK_UNINTERRUPTIBLE); 844 i = drbd_find_overlap(&mdev->write_requests, sector, size); 845 if (!i) 846 break; 847 /* Indicate to wake up device->misc_wait on progress. */ 848 i->waiting = true; 849 spin_unlock_irq(&mdev->tconn->req_lock); 850 schedule(); 851 spin_lock_irq(&mdev->tconn->req_lock); 852 } 853 finish_wait(&mdev->misc_wait, &wait); 854 } 855 856 /* called within req_lock and rcu_read_lock() */ 857 static void maybe_pull_ahead(struct drbd_conf *mdev) 858 { 859 struct drbd_tconn *tconn = mdev->tconn; 860 struct net_conf *nc; 861 bool congested = false; 862 enum drbd_on_congestion on_congestion; 863 864 nc = rcu_dereference(tconn->net_conf); 865 on_congestion = nc ? nc->on_congestion : OC_BLOCK; 866 if (on_congestion == OC_BLOCK || 867 tconn->agreed_pro_version < 96) 868 return; 869 870 /* If I don't even have good local storage, we can not reasonably try 871 * to pull ahead of the peer. We also need the local reference to make 872 * sure mdev->act_log is there. 873 */ 874 if (!get_ldev_if_state(mdev, D_UP_TO_DATE)) 875 return; 876 877 if (nc->cong_fill && 878 atomic_read(&mdev->ap_in_flight) >= nc->cong_fill) { 879 dev_info(DEV, "Congestion-fill threshold reached\n"); 880 congested = true; 881 } 882 883 if (mdev->act_log->used >= nc->cong_extents) { 884 dev_info(DEV, "Congestion-extents threshold reached\n"); 885 congested = true; 886 } 887 888 if (congested) { 889 /* start a new epoch for non-mirrored writes */ 890 start_new_tl_epoch(mdev->tconn); 891 892 if (on_congestion == OC_PULL_AHEAD) 893 _drbd_set_state(_NS(mdev, conn, C_AHEAD), 0, NULL); 894 else /*nc->on_congestion == OC_DISCONNECT */ 895 _drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL); 896 } 897 put_ldev(mdev); 898 } 899 900 /* If this returns false, and req->private_bio is still set, 901 * this should be submitted locally. 902 * 903 * If it returns false, but req->private_bio is not set, 904 * we do not have access to good data :( 905 * 906 * Otherwise, this destroys req->private_bio, if any, 907 * and returns true. 908 */ 909 static bool do_remote_read(struct drbd_request *req) 910 { 911 struct drbd_conf *mdev = req->w.mdev; 912 enum drbd_read_balancing rbm; 913 914 if (req->private_bio) { 915 if (!drbd_may_do_local_read(mdev, 916 req->i.sector, req->i.size)) { 917 bio_put(req->private_bio); 918 req->private_bio = NULL; 919 put_ldev(mdev); 920 } 921 } 922 923 if (mdev->state.pdsk != D_UP_TO_DATE) 924 return false; 925 926 if (req->private_bio == NULL) 927 return true; 928 929 /* TODO: improve read balancing decisions, take into account drbd 930 * protocol, pending requests etc. */ 931 932 rcu_read_lock(); 933 rbm = rcu_dereference(mdev->ldev->disk_conf)->read_balancing; 934 rcu_read_unlock(); 935 936 if (rbm == RB_PREFER_LOCAL && req->private_bio) 937 return false; /* submit locally */ 938 939 if (remote_due_to_read_balancing(mdev, req->i.sector, rbm)) { 940 if (req->private_bio) { 941 bio_put(req->private_bio); 942 req->private_bio = NULL; 943 put_ldev(mdev); 944 } 945 return true; 946 } 947 948 return false; 949 } 950 951 /* returns number of connections (== 1, for drbd 8.4) 952 * expected to actually write this data, 953 * which does NOT include those that we are L_AHEAD for. */ 954 static int drbd_process_write_request(struct drbd_request *req) 955 { 956 struct drbd_conf *mdev = req->w.mdev; 957 int remote, send_oos; 958 959 rcu_read_lock(); 960 remote = drbd_should_do_remote(mdev->state); 961 if (remote) { 962 maybe_pull_ahead(mdev); 963 remote = drbd_should_do_remote(mdev->state); 964 } 965 send_oos = drbd_should_send_out_of_sync(mdev->state); 966 rcu_read_unlock(); 967 968 /* Need to replicate writes. Unless it is an empty flush, 969 * which is better mapped to a DRBD P_BARRIER packet, 970 * also for drbd wire protocol compatibility reasons. 971 * If this was a flush, just start a new epoch. 972 * Unless the current epoch was empty anyways, or we are not currently 973 * replicating, in which case there is no point. */ 974 if (unlikely(req->i.size == 0)) { 975 /* The only size==0 bios we expect are empty flushes. */ 976 D_ASSERT(req->master_bio->bi_rw & REQ_FLUSH); 977 if (remote) 978 start_new_tl_epoch(mdev->tconn); 979 return 0; 980 } 981 982 if (!remote && !send_oos) 983 return 0; 984 985 D_ASSERT(!(remote && send_oos)); 986 987 if (remote) { 988 _req_mod(req, TO_BE_SENT); 989 _req_mod(req, QUEUE_FOR_NET_WRITE); 990 } else if (drbd_set_out_of_sync(mdev, req->i.sector, req->i.size)) 991 _req_mod(req, QUEUE_FOR_SEND_OOS); 992 993 return remote; 994 } 995 996 static void 997 drbd_submit_req_private_bio(struct drbd_request *req) 998 { 999 struct drbd_conf *mdev = req->w.mdev; 1000 struct bio *bio = req->private_bio; 1001 const int rw = bio_rw(bio); 1002 1003 bio->bi_bdev = mdev->ldev->backing_bdev; 1004 1005 /* State may have changed since we grabbed our reference on the 1006 * ->ldev member. Double check, and short-circuit to endio. 1007 * In case the last activity log transaction failed to get on 1008 * stable storage, and this is a WRITE, we may not even submit 1009 * this bio. */ 1010 if (get_ldev(mdev)) { 1011 if (drbd_insert_fault(mdev, 1012 rw == WRITE ? DRBD_FAULT_DT_WR 1013 : rw == READ ? DRBD_FAULT_DT_RD 1014 : DRBD_FAULT_DT_RA)) 1015 bio_endio(bio, -EIO); 1016 else 1017 generic_make_request(bio); 1018 put_ldev(mdev); 1019 } else 1020 bio_endio(bio, -EIO); 1021 } 1022 1023 void __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long start_time) 1024 { 1025 const int rw = bio_rw(bio); 1026 struct bio_and_error m = { NULL, }; 1027 struct drbd_request *req; 1028 bool no_remote = false; 1029 1030 /* allocate outside of all locks; */ 1031 req = drbd_req_new(mdev, bio); 1032 if (!req) { 1033 dec_ap_bio(mdev); 1034 /* only pass the error to the upper layers. 1035 * if user cannot handle io errors, that's not our business. */ 1036 dev_err(DEV, "could not kmalloc() req\n"); 1037 bio_endio(bio, -ENOMEM); 1038 return; 1039 } 1040 req->start_time = start_time; 1041 1042 if (!get_ldev(mdev)) { 1043 bio_put(req->private_bio); 1044 req->private_bio = NULL; 1045 } 1046 1047 /* For WRITES going to the local disk, grab a reference on the target 1048 * extent. This waits for any resync activity in the corresponding 1049 * resync extent to finish, and, if necessary, pulls in the target 1050 * extent into the activity log, which involves further disk io because 1051 * of transactional on-disk meta data updates. 1052 * Empty flushes don't need to go into the activity log, they can only 1053 * flush data for pending writes which are already in there. */ 1054 if (rw == WRITE && req->private_bio && req->i.size 1055 && !test_bit(AL_SUSPENDED, &mdev->flags)) { 1056 req->rq_state |= RQ_IN_ACT_LOG; 1057 drbd_al_begin_io(mdev, &req->i); 1058 } 1059 1060 spin_lock_irq(&mdev->tconn->req_lock); 1061 if (rw == WRITE) { 1062 /* This may temporarily give up the req_lock, 1063 * but will re-aquire it before it returns here. 1064 * Needs to be before the check on drbd_suspended() */ 1065 complete_conflicting_writes(req); 1066 } 1067 1068 /* no more giving up req_lock from now on! */ 1069 1070 if (drbd_suspended(mdev)) { 1071 /* push back and retry: */ 1072 req->rq_state |= RQ_POSTPONED; 1073 if (req->private_bio) { 1074 bio_put(req->private_bio); 1075 req->private_bio = NULL; 1076 put_ldev(mdev); 1077 } 1078 goto out; 1079 } 1080 1081 /* Update disk stats */ 1082 _drbd_start_io_acct(mdev, req, bio); 1083 1084 /* We fail READ/READA early, if we can not serve it. 1085 * We must do this before req is registered on any lists. 1086 * Otherwise, drbd_req_complete() will queue failed READ for retry. */ 1087 if (rw != WRITE) { 1088 if (!do_remote_read(req) && !req->private_bio) 1089 goto nodata; 1090 } 1091 1092 /* which transfer log epoch does this belong to? */ 1093 req->epoch = atomic_read(&mdev->tconn->current_tle_nr); 1094 1095 /* no point in adding empty flushes to the transfer log, 1096 * they are mapped to drbd barriers already. */ 1097 if (likely(req->i.size!=0)) { 1098 if (rw == WRITE) 1099 mdev->tconn->current_tle_writes++; 1100 1101 list_add_tail(&req->tl_requests, &mdev->tconn->transfer_log); 1102 } 1103 1104 if (rw == WRITE) { 1105 if (!drbd_process_write_request(req)) 1106 no_remote = true; 1107 } else { 1108 /* We either have a private_bio, or we can read from remote. 1109 * Otherwise we had done the goto nodata above. */ 1110 if (req->private_bio == NULL) { 1111 _req_mod(req, TO_BE_SENT); 1112 _req_mod(req, QUEUE_FOR_NET_READ); 1113 } else 1114 no_remote = true; 1115 } 1116 1117 if (req->private_bio) { 1118 /* needs to be marked within the same spinlock */ 1119 _req_mod(req, TO_BE_SUBMITTED); 1120 /* but we need to give up the spinlock to submit */ 1121 spin_unlock_irq(&mdev->tconn->req_lock); 1122 drbd_submit_req_private_bio(req); 1123 spin_lock_irq(&mdev->tconn->req_lock); 1124 } else if (no_remote) { 1125 nodata: 1126 if (__ratelimit(&drbd_ratelimit_state)) 1127 dev_err(DEV, "IO ERROR: neither local nor remote data, sector %llu+%u\n", 1128 (unsigned long long)req->i.sector, req->i.size >> 9); 1129 /* A write may have been queued for send_oos, however. 1130 * So we can not simply free it, we must go through drbd_req_put_completion_ref() */ 1131 } 1132 1133 out: 1134 if (drbd_req_put_completion_ref(req, &m, 1)) 1135 kref_put(&req->kref, drbd_req_destroy); 1136 spin_unlock_irq(&mdev->tconn->req_lock); 1137 1138 if (m.bio) 1139 complete_master_bio(mdev, &m); 1140 return; 1141 } 1142 1143 void drbd_make_request(struct request_queue *q, struct bio *bio) 1144 { 1145 struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata; 1146 unsigned long start_time; 1147 1148 start_time = jiffies; 1149 1150 /* 1151 * what we "blindly" assume: 1152 */ 1153 D_ASSERT(IS_ALIGNED(bio->bi_size, 512)); 1154 1155 inc_ap_bio(mdev); 1156 __drbd_make_request(mdev, bio, start_time); 1157 } 1158 1159 /* This is called by bio_add_page(). 1160 * 1161 * q->max_hw_sectors and other global limits are already enforced there. 1162 * 1163 * We need to call down to our lower level device, 1164 * in case it has special restrictions. 1165 * 1166 * We also may need to enforce configured max-bio-bvecs limits. 1167 * 1168 * As long as the BIO is empty we have to allow at least one bvec, 1169 * regardless of size and offset, so no need to ask lower levels. 1170 */ 1171 int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec) 1172 { 1173 struct drbd_conf *mdev = (struct drbd_conf *) q->queuedata; 1174 unsigned int bio_size = bvm->bi_size; 1175 int limit = DRBD_MAX_BIO_SIZE; 1176 int backing_limit; 1177 1178 if (bio_size && get_ldev(mdev)) { 1179 struct request_queue * const b = 1180 mdev->ldev->backing_bdev->bd_disk->queue; 1181 if (b->merge_bvec_fn) { 1182 backing_limit = b->merge_bvec_fn(b, bvm, bvec); 1183 limit = min(limit, backing_limit); 1184 } 1185 put_ldev(mdev); 1186 } 1187 return limit; 1188 } 1189 1190 struct drbd_request *find_oldest_request(struct drbd_tconn *tconn) 1191 { 1192 /* Walk the transfer log, 1193 * and find the oldest not yet completed request */ 1194 struct drbd_request *r; 1195 list_for_each_entry(r, &tconn->transfer_log, tl_requests) { 1196 if (atomic_read(&r->completion_ref)) 1197 return r; 1198 } 1199 return NULL; 1200 } 1201 1202 void request_timer_fn(unsigned long data) 1203 { 1204 struct drbd_conf *mdev = (struct drbd_conf *) data; 1205 struct drbd_tconn *tconn = mdev->tconn; 1206 struct drbd_request *req; /* oldest request */ 1207 struct net_conf *nc; 1208 unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */ 1209 unsigned long now; 1210 1211 rcu_read_lock(); 1212 nc = rcu_dereference(tconn->net_conf); 1213 if (nc && mdev->state.conn >= C_WF_REPORT_PARAMS) 1214 ent = nc->timeout * HZ/10 * nc->ko_count; 1215 1216 if (get_ldev(mdev)) { /* implicit state.disk >= D_INCONSISTENT */ 1217 dt = rcu_dereference(mdev->ldev->disk_conf)->disk_timeout * HZ / 10; 1218 put_ldev(mdev); 1219 } 1220 rcu_read_unlock(); 1221 1222 et = min_not_zero(dt, ent); 1223 1224 if (!et) 1225 return; /* Recurring timer stopped */ 1226 1227 now = jiffies; 1228 1229 spin_lock_irq(&tconn->req_lock); 1230 req = find_oldest_request(tconn); 1231 if (!req) { 1232 spin_unlock_irq(&tconn->req_lock); 1233 mod_timer(&mdev->request_timer, now + et); 1234 return; 1235 } 1236 1237 /* The request is considered timed out, if 1238 * - we have some effective timeout from the configuration, 1239 * with above state restrictions applied, 1240 * - the oldest request is waiting for a response from the network 1241 * resp. the local disk, 1242 * - the oldest request is in fact older than the effective timeout, 1243 * - the connection was established (resp. disk was attached) 1244 * for longer than the timeout already. 1245 * Note that for 32bit jiffies and very stable connections/disks, 1246 * we may have a wrap around, which is catched by 1247 * !time_in_range(now, last_..._jif, last_..._jif + timeout). 1248 * 1249 * Side effect: once per 32bit wrap-around interval, which means every 1250 * ~198 days with 250 HZ, we have a window where the timeout would need 1251 * to expire twice (worst case) to become effective. Good enough. 1252 */ 1253 if (ent && req->rq_state & RQ_NET_PENDING && 1254 time_after(now, req->start_time + ent) && 1255 !time_in_range(now, tconn->last_reconnect_jif, tconn->last_reconnect_jif + ent)) { 1256 dev_warn(DEV, "Remote failed to finish a request within ko-count * timeout\n"); 1257 _drbd_set_state(_NS(mdev, conn, C_TIMEOUT), CS_VERBOSE | CS_HARD, NULL); 1258 } 1259 if (dt && req->rq_state & RQ_LOCAL_PENDING && req->w.mdev == mdev && 1260 time_after(now, req->start_time + dt) && 1261 !time_in_range(now, mdev->last_reattach_jif, mdev->last_reattach_jif + dt)) { 1262 dev_warn(DEV, "Local backing device failed to meet the disk-timeout\n"); 1263 __drbd_chk_io_error(mdev, DRBD_FORCE_DETACH); 1264 } 1265 nt = (time_after(now, req->start_time + et) ? now : req->start_time) + et; 1266 spin_unlock_irq(&tconn->req_lock); 1267 mod_timer(&mdev->request_timer, nt); 1268 } 1269