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_device *device, 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_device *device, struct drbd_request *req) 38 { 39 struct request_queue *q = device->rq_queue; 40 41 generic_start_io_acct(q, bio_data_dir(req->master_bio), 42 req->i.size >> 9, &device->vdisk->part0); 43 } 44 45 /* Update disk stats when completing request upwards */ 46 static void _drbd_end_io_acct(struct drbd_device *device, struct drbd_request *req) 47 { 48 struct request_queue *q = device->rq_queue; 49 50 generic_end_io_acct(q, bio_data_dir(req->master_bio), 51 &device->vdisk->part0, req->start_jif); 52 } 53 54 static struct drbd_request *drbd_req_new(struct drbd_device *device, struct bio *bio_src) 55 { 56 struct drbd_request *req; 57 58 req = mempool_alloc(drbd_request_mempool, GFP_NOIO); 59 if (!req) 60 return NULL; 61 memset(req, 0, sizeof(*req)); 62 63 drbd_req_make_private_bio(req, bio_src); 64 req->rq_state = (bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0) 65 | (bio_op(bio_src) == REQ_OP_WRITE_SAME ? RQ_WSAME : 0) 66 | (bio_op(bio_src) == REQ_OP_WRITE_ZEROES ? RQ_UNMAP : 0) 67 | (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 0); 68 req->device = device; 69 req->master_bio = bio_src; 70 req->epoch = 0; 71 72 drbd_clear_interval(&req->i); 73 req->i.sector = bio_src->bi_iter.bi_sector; 74 req->i.size = bio_src->bi_iter.bi_size; 75 req->i.local = true; 76 req->i.waiting = false; 77 78 INIT_LIST_HEAD(&req->tl_requests); 79 INIT_LIST_HEAD(&req->w.list); 80 INIT_LIST_HEAD(&req->req_pending_master_completion); 81 INIT_LIST_HEAD(&req->req_pending_local); 82 83 /* one reference to be put by __drbd_make_request */ 84 atomic_set(&req->completion_ref, 1); 85 /* one kref as long as completion_ref > 0 */ 86 kref_init(&req->kref); 87 return req; 88 } 89 90 static void drbd_remove_request_interval(struct rb_root *root, 91 struct drbd_request *req) 92 { 93 struct drbd_device *device = req->device; 94 struct drbd_interval *i = &req->i; 95 96 drbd_remove_interval(root, i); 97 98 /* Wake up any processes waiting for this request to complete. */ 99 if (i->waiting) 100 wake_up(&device->misc_wait); 101 } 102 103 void drbd_req_destroy(struct kref *kref) 104 { 105 struct drbd_request *req = container_of(kref, struct drbd_request, kref); 106 struct drbd_device *device = req->device; 107 const unsigned s = req->rq_state; 108 109 if ((req->master_bio && !(s & RQ_POSTPONED)) || 110 atomic_read(&req->completion_ref) || 111 (s & RQ_LOCAL_PENDING) || 112 ((s & RQ_NET_MASK) && !(s & RQ_NET_DONE))) { 113 drbd_err(device, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n", 114 s, atomic_read(&req->completion_ref)); 115 return; 116 } 117 118 /* If called from mod_rq_state (expected normal case) or 119 * drbd_send_and_submit (the less likely normal path), this holds the 120 * req_lock, and req->tl_requests will typicaly be on ->transfer_log, 121 * though it may be still empty (never added to the transfer log). 122 * 123 * If called from do_retry(), we do NOT hold the req_lock, but we are 124 * still allowed to unconditionally list_del(&req->tl_requests), 125 * because it will be on a local on-stack list only. */ 126 list_del_init(&req->tl_requests); 127 128 /* finally remove the request from the conflict detection 129 * respective block_id verification interval tree. */ 130 if (!drbd_interval_empty(&req->i)) { 131 struct rb_root *root; 132 133 if (s & RQ_WRITE) 134 root = &device->write_requests; 135 else 136 root = &device->read_requests; 137 drbd_remove_request_interval(root, req); 138 } else if (s & (RQ_NET_MASK & ~RQ_NET_DONE) && req->i.size != 0) 139 drbd_err(device, "drbd_req_destroy: Logic BUG: interval empty, but: rq_state=0x%x, sect=%llu, size=%u\n", 140 s, (unsigned long long)req->i.sector, req->i.size); 141 142 /* if it was a write, we may have to set the corresponding 143 * bit(s) out-of-sync first. If it had a local part, we need to 144 * release the reference to the activity log. */ 145 if (s & RQ_WRITE) { 146 /* Set out-of-sync unless both OK flags are set 147 * (local only or remote failed). 148 * Other places where we set out-of-sync: 149 * READ with local io-error */ 150 151 /* There is a special case: 152 * we may notice late that IO was suspended, 153 * and postpone, or schedule for retry, a write, 154 * before it even was submitted or sent. 155 * In that case we do not want to touch the bitmap at all. 156 */ 157 if ((s & (RQ_POSTPONED|RQ_LOCAL_MASK|RQ_NET_MASK)) != RQ_POSTPONED) { 158 if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK)) 159 drbd_set_out_of_sync(device, req->i.sector, req->i.size); 160 161 if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS)) 162 drbd_set_in_sync(device, req->i.sector, req->i.size); 163 } 164 165 /* one might be tempted to move the drbd_al_complete_io 166 * to the local io completion callback drbd_request_endio. 167 * but, if this was a mirror write, we may only 168 * drbd_al_complete_io after this is RQ_NET_DONE, 169 * otherwise the extent could be dropped from the al 170 * before it has actually been written on the peer. 171 * if we crash before our peer knows about the request, 172 * but after the extent has been dropped from the al, 173 * we would forget to resync the corresponding extent. 174 */ 175 if (s & RQ_IN_ACT_LOG) { 176 if (get_ldev_if_state(device, D_FAILED)) { 177 drbd_al_complete_io(device, &req->i); 178 put_ldev(device); 179 } else if (__ratelimit(&drbd_ratelimit_state)) { 180 drbd_warn(device, "Should have called drbd_al_complete_io(, %llu, %u), " 181 "but my Disk seems to have failed :(\n", 182 (unsigned long long) req->i.sector, req->i.size); 183 } 184 } 185 } 186 187 mempool_free(req, drbd_request_mempool); 188 } 189 190 static void wake_all_senders(struct drbd_connection *connection) 191 { 192 wake_up(&connection->sender_work.q_wait); 193 } 194 195 /* must hold resource->req_lock */ 196 void start_new_tl_epoch(struct drbd_connection *connection) 197 { 198 /* no point closing an epoch, if it is empty, anyways. */ 199 if (connection->current_tle_writes == 0) 200 return; 201 202 connection->current_tle_writes = 0; 203 atomic_inc(&connection->current_tle_nr); 204 wake_all_senders(connection); 205 } 206 207 void complete_master_bio(struct drbd_device *device, 208 struct bio_and_error *m) 209 { 210 m->bio->bi_status = errno_to_blk_status(m->error); 211 bio_endio(m->bio); 212 dec_ap_bio(device); 213 } 214 215 216 /* Helper for __req_mod(). 217 * Set m->bio to the master bio, if it is fit to be completed, 218 * or leave it alone (it is initialized to NULL in __req_mod), 219 * if it has already been completed, or cannot be completed yet. 220 * If m->bio is set, the error status to be returned is placed in m->error. 221 */ 222 static 223 void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m) 224 { 225 const unsigned s = req->rq_state; 226 struct drbd_device *device = req->device; 227 int error, ok; 228 229 /* we must not complete the master bio, while it is 230 * still being processed by _drbd_send_zc_bio (drbd_send_dblock) 231 * not yet acknowledged by the peer 232 * not yet completed by the local io subsystem 233 * these flags may get cleared in any order by 234 * the worker, 235 * the receiver, 236 * the bio_endio completion callbacks. 237 */ 238 if ((s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED)) || 239 (s & RQ_NET_QUEUED) || (s & RQ_NET_PENDING) || 240 (s & RQ_COMPLETION_SUSP)) { 241 drbd_err(device, "drbd_req_complete: Logic BUG rq_state = 0x%x\n", s); 242 return; 243 } 244 245 if (!req->master_bio) { 246 drbd_err(device, "drbd_req_complete: Logic BUG, master_bio == NULL!\n"); 247 return; 248 } 249 250 /* 251 * figure out whether to report success or failure. 252 * 253 * report success when at least one of the operations succeeded. 254 * or, to put the other way, 255 * only report failure, when both operations failed. 256 * 257 * what to do about the failures is handled elsewhere. 258 * what we need to do here is just: complete the master_bio. 259 * 260 * local completion error, if any, has been stored as ERR_PTR 261 * in private_bio within drbd_request_endio. 262 */ 263 ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK); 264 error = PTR_ERR(req->private_bio); 265 266 /* Before we can signal completion to the upper layers, 267 * we may need to close the current transfer log epoch. 268 * We are within the request lock, so we can simply compare 269 * the request epoch number with the current transfer log 270 * epoch number. If they match, increase the current_tle_nr, 271 * and reset the transfer log epoch write_cnt. 272 */ 273 if (op_is_write(bio_op(req->master_bio)) && 274 req->epoch == atomic_read(&first_peer_device(device)->connection->current_tle_nr)) 275 start_new_tl_epoch(first_peer_device(device)->connection); 276 277 /* Update disk stats */ 278 _drbd_end_io_acct(device, req); 279 280 /* If READ failed, 281 * have it be pushed back to the retry work queue, 282 * so it will re-enter __drbd_make_request(), 283 * and be re-assigned to a suitable local or remote path, 284 * or failed if we do not have access to good data anymore. 285 * 286 * Unless it was failed early by __drbd_make_request(), 287 * because no path was available, in which case 288 * it was not even added to the transfer_log. 289 * 290 * read-ahead may fail, and will not be retried. 291 * 292 * WRITE should have used all available paths already. 293 */ 294 if (!ok && 295 bio_op(req->master_bio) == REQ_OP_READ && 296 !(req->master_bio->bi_opf & REQ_RAHEAD) && 297 !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 /* We leave it in the tree, to be able to verify later 305 * write-acks in protocol != C during resync. 306 * But we mark it as "complete", so it won't be counted as 307 * conflict in a multi-primary setup. */ 308 req->i.completed = true; 309 } 310 311 if (req->i.waiting) 312 wake_up(&device->misc_wait); 313 314 /* Either we are about to complete to upper layers, 315 * or we will restart this request. 316 * In either case, the request object will be destroyed soon, 317 * so better remove it from all lists. */ 318 list_del_init(&req->req_pending_master_completion); 319 } 320 321 /* still holds resource->req_lock */ 322 static void drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put) 323 { 324 struct drbd_device *device = req->device; 325 D_ASSERT(device, m || (req->rq_state & RQ_POSTPONED)); 326 327 if (!put) 328 return; 329 330 if (!atomic_sub_and_test(put, &req->completion_ref)) 331 return; 332 333 drbd_req_complete(req, m); 334 335 /* local completion may still come in later, 336 * we need to keep the req object around. */ 337 if (req->rq_state & RQ_LOCAL_ABORTED) 338 return; 339 340 if (req->rq_state & RQ_POSTPONED) { 341 /* don't destroy the req object just yet, 342 * but queue it for retry */ 343 drbd_restart_request(req); 344 return; 345 } 346 347 kref_put(&req->kref, drbd_req_destroy); 348 } 349 350 static void set_if_null_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req) 351 { 352 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; 353 if (!connection) 354 return; 355 if (connection->req_next == NULL) 356 connection->req_next = req; 357 } 358 359 static void advance_conn_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req) 360 { 361 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; 362 if (!connection) 363 return; 364 if (connection->req_next != req) 365 return; 366 list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) { 367 const unsigned s = req->rq_state; 368 if (s & RQ_NET_QUEUED) 369 break; 370 } 371 if (&req->tl_requests == &connection->transfer_log) 372 req = NULL; 373 connection->req_next = req; 374 } 375 376 static void set_if_null_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req) 377 { 378 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; 379 if (!connection) 380 return; 381 if (connection->req_ack_pending == NULL) 382 connection->req_ack_pending = req; 383 } 384 385 static void advance_conn_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req) 386 { 387 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; 388 if (!connection) 389 return; 390 if (connection->req_ack_pending != req) 391 return; 392 list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) { 393 const unsigned s = req->rq_state; 394 if ((s & RQ_NET_SENT) && (s & RQ_NET_PENDING)) 395 break; 396 } 397 if (&req->tl_requests == &connection->transfer_log) 398 req = NULL; 399 connection->req_ack_pending = req; 400 } 401 402 static void set_if_null_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req) 403 { 404 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; 405 if (!connection) 406 return; 407 if (connection->req_not_net_done == NULL) 408 connection->req_not_net_done = req; 409 } 410 411 static void advance_conn_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req) 412 { 413 struct drbd_connection *connection = peer_device ? peer_device->connection : NULL; 414 if (!connection) 415 return; 416 if (connection->req_not_net_done != req) 417 return; 418 list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) { 419 const unsigned s = req->rq_state; 420 if ((s & RQ_NET_SENT) && !(s & RQ_NET_DONE)) 421 break; 422 } 423 if (&req->tl_requests == &connection->transfer_log) 424 req = NULL; 425 connection->req_not_net_done = req; 426 } 427 428 /* I'd like this to be the only place that manipulates 429 * req->completion_ref and req->kref. */ 430 static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, 431 int clear, int set) 432 { 433 struct drbd_device *device = req->device; 434 struct drbd_peer_device *peer_device = first_peer_device(device); 435 unsigned s = req->rq_state; 436 int c_put = 0; 437 438 if (drbd_suspended(device) && !((s | clear) & RQ_COMPLETION_SUSP)) 439 set |= RQ_COMPLETION_SUSP; 440 441 /* apply */ 442 443 req->rq_state &= ~clear; 444 req->rq_state |= set; 445 446 /* no change? */ 447 if (req->rq_state == s) 448 return; 449 450 /* intent: get references */ 451 452 kref_get(&req->kref); 453 454 if (!(s & RQ_LOCAL_PENDING) && (set & RQ_LOCAL_PENDING)) 455 atomic_inc(&req->completion_ref); 456 457 if (!(s & RQ_NET_PENDING) && (set & RQ_NET_PENDING)) { 458 inc_ap_pending(device); 459 atomic_inc(&req->completion_ref); 460 } 461 462 if (!(s & RQ_NET_QUEUED) && (set & RQ_NET_QUEUED)) { 463 atomic_inc(&req->completion_ref); 464 set_if_null_req_next(peer_device, req); 465 } 466 467 if (!(s & RQ_EXP_BARR_ACK) && (set & RQ_EXP_BARR_ACK)) 468 kref_get(&req->kref); /* wait for the DONE */ 469 470 if (!(s & RQ_NET_SENT) && (set & RQ_NET_SENT)) { 471 /* potentially already completed in the ack_receiver thread */ 472 if (!(s & RQ_NET_DONE)) { 473 atomic_add(req->i.size >> 9, &device->ap_in_flight); 474 set_if_null_req_not_net_done(peer_device, req); 475 } 476 if (req->rq_state & RQ_NET_PENDING) 477 set_if_null_req_ack_pending(peer_device, req); 478 } 479 480 if (!(s & RQ_COMPLETION_SUSP) && (set & RQ_COMPLETION_SUSP)) 481 atomic_inc(&req->completion_ref); 482 483 /* progress: put references */ 484 485 if ((s & RQ_COMPLETION_SUSP) && (clear & RQ_COMPLETION_SUSP)) 486 ++c_put; 487 488 if (!(s & RQ_LOCAL_ABORTED) && (set & RQ_LOCAL_ABORTED)) { 489 D_ASSERT(device, req->rq_state & RQ_LOCAL_PENDING); 490 ++c_put; 491 } 492 493 if ((s & RQ_LOCAL_PENDING) && (clear & RQ_LOCAL_PENDING)) { 494 if (req->rq_state & RQ_LOCAL_ABORTED) 495 kref_put(&req->kref, drbd_req_destroy); 496 else 497 ++c_put; 498 list_del_init(&req->req_pending_local); 499 } 500 501 if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) { 502 dec_ap_pending(device); 503 ++c_put; 504 req->acked_jif = jiffies; 505 advance_conn_req_ack_pending(peer_device, req); 506 } 507 508 if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED)) { 509 ++c_put; 510 advance_conn_req_next(peer_device, req); 511 } 512 513 if (!(s & RQ_NET_DONE) && (set & RQ_NET_DONE)) { 514 if (s & RQ_NET_SENT) 515 atomic_sub(req->i.size >> 9, &device->ap_in_flight); 516 if (s & RQ_EXP_BARR_ACK) 517 kref_put(&req->kref, drbd_req_destroy); 518 req->net_done_jif = jiffies; 519 520 /* in ahead/behind mode, or just in case, 521 * before we finally destroy this request, 522 * the caching pointers must not reference it anymore */ 523 advance_conn_req_next(peer_device, req); 524 advance_conn_req_ack_pending(peer_device, req); 525 advance_conn_req_not_net_done(peer_device, req); 526 } 527 528 /* potentially complete and destroy */ 529 530 /* If we made progress, retry conflicting peer requests, if any. */ 531 if (req->i.waiting) 532 wake_up(&device->misc_wait); 533 534 drbd_req_put_completion_ref(req, m, c_put); 535 kref_put(&req->kref, drbd_req_destroy); 536 } 537 538 static void drbd_report_io_error(struct drbd_device *device, struct drbd_request *req) 539 { 540 char b[BDEVNAME_SIZE]; 541 542 if (!__ratelimit(&drbd_ratelimit_state)) 543 return; 544 545 drbd_warn(device, "local %s IO error sector %llu+%u on %s\n", 546 (req->rq_state & RQ_WRITE) ? "WRITE" : "READ", 547 (unsigned long long)req->i.sector, 548 req->i.size >> 9, 549 bdevname(device->ldev->backing_bdev, b)); 550 } 551 552 /* Helper for HANDED_OVER_TO_NETWORK. 553 * Is this a protocol A write (neither WRITE_ACK nor RECEIVE_ACK expected)? 554 * Is it also still "PENDING"? 555 * --> If so, clear PENDING and set NET_OK below. 556 * If it is a protocol A write, but not RQ_PENDING anymore, neg-ack was faster 557 * (and we must not set RQ_NET_OK) */ 558 static inline bool is_pending_write_protocol_A(struct drbd_request *req) 559 { 560 return (req->rq_state & 561 (RQ_WRITE|RQ_NET_PENDING|RQ_EXP_WRITE_ACK|RQ_EXP_RECEIVE_ACK)) 562 == (RQ_WRITE|RQ_NET_PENDING); 563 } 564 565 /* obviously this could be coded as many single functions 566 * instead of one huge switch, 567 * or by putting the code directly in the respective locations 568 * (as it has been before). 569 * 570 * but having it this way 571 * enforces that it is all in this one place, where it is easier to audit, 572 * it makes it obvious that whatever "event" "happens" to a request should 573 * happen "atomically" within the req_lock, 574 * and it enforces that we have to think in a very structured manner 575 * about the "events" that may happen to a request during its life time ... 576 */ 577 int __req_mod(struct drbd_request *req, enum drbd_req_event what, 578 struct bio_and_error *m) 579 { 580 struct drbd_device *const device = req->device; 581 struct drbd_peer_device *const peer_device = first_peer_device(device); 582 struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL; 583 struct net_conf *nc; 584 int p, rv = 0; 585 586 if (m) 587 m->bio = NULL; 588 589 switch (what) { 590 default: 591 drbd_err(device, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__); 592 break; 593 594 /* does not happen... 595 * initialization done in drbd_req_new 596 case CREATED: 597 break; 598 */ 599 600 case TO_BE_SENT: /* via network */ 601 /* reached via __drbd_make_request 602 * and from w_read_retry_remote */ 603 D_ASSERT(device, !(req->rq_state & RQ_NET_MASK)); 604 rcu_read_lock(); 605 nc = rcu_dereference(connection->net_conf); 606 p = nc->wire_protocol; 607 rcu_read_unlock(); 608 req->rq_state |= 609 p == DRBD_PROT_C ? RQ_EXP_WRITE_ACK : 610 p == DRBD_PROT_B ? RQ_EXP_RECEIVE_ACK : 0; 611 mod_rq_state(req, m, 0, RQ_NET_PENDING); 612 break; 613 614 case TO_BE_SUBMITTED: /* locally */ 615 /* reached via __drbd_make_request */ 616 D_ASSERT(device, !(req->rq_state & RQ_LOCAL_MASK)); 617 mod_rq_state(req, m, 0, RQ_LOCAL_PENDING); 618 break; 619 620 case COMPLETED_OK: 621 if (req->rq_state & RQ_WRITE) 622 device->writ_cnt += req->i.size >> 9; 623 else 624 device->read_cnt += req->i.size >> 9; 625 626 mod_rq_state(req, m, RQ_LOCAL_PENDING, 627 RQ_LOCAL_COMPLETED|RQ_LOCAL_OK); 628 break; 629 630 case ABORT_DISK_IO: 631 mod_rq_state(req, m, 0, RQ_LOCAL_ABORTED); 632 break; 633 634 case WRITE_COMPLETED_WITH_ERROR: 635 drbd_report_io_error(device, req); 636 __drbd_chk_io_error(device, DRBD_WRITE_ERROR); 637 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED); 638 break; 639 640 case READ_COMPLETED_WITH_ERROR: 641 drbd_set_out_of_sync(device, req->i.sector, req->i.size); 642 drbd_report_io_error(device, req); 643 __drbd_chk_io_error(device, DRBD_READ_ERROR); 644 /* fall through. */ 645 case READ_AHEAD_COMPLETED_WITH_ERROR: 646 /* it is legal to fail read-ahead, no __drbd_chk_io_error in that case. */ 647 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED); 648 break; 649 650 case DISCARD_COMPLETED_NOTSUPP: 651 case DISCARD_COMPLETED_WITH_ERROR: 652 /* I'd rather not detach from local disk just because it 653 * failed a REQ_DISCARD. */ 654 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED); 655 break; 656 657 case QUEUE_FOR_NET_READ: 658 /* READ, and 659 * no local disk, 660 * or target area marked as invalid, 661 * or just got an io-error. */ 662 /* from __drbd_make_request 663 * or from bio_endio during read io-error recovery */ 664 665 /* So we can verify the handle in the answer packet. 666 * Corresponding drbd_remove_request_interval is in 667 * drbd_req_complete() */ 668 D_ASSERT(device, drbd_interval_empty(&req->i)); 669 drbd_insert_interval(&device->read_requests, &req->i); 670 671 set_bit(UNPLUG_REMOTE, &device->flags); 672 673 D_ASSERT(device, req->rq_state & RQ_NET_PENDING); 674 D_ASSERT(device, (req->rq_state & RQ_LOCAL_MASK) == 0); 675 mod_rq_state(req, m, 0, RQ_NET_QUEUED); 676 req->w.cb = w_send_read_req; 677 drbd_queue_work(&connection->sender_work, 678 &req->w); 679 break; 680 681 case QUEUE_FOR_NET_WRITE: 682 /* assert something? */ 683 /* from __drbd_make_request only */ 684 685 /* Corresponding drbd_remove_request_interval is in 686 * drbd_req_complete() */ 687 D_ASSERT(device, drbd_interval_empty(&req->i)); 688 drbd_insert_interval(&device->write_requests, &req->i); 689 690 /* NOTE 691 * In case the req ended up on the transfer log before being 692 * queued on the worker, it could lead to this request being 693 * missed during cleanup after connection loss. 694 * So we have to do both operations here, 695 * within the same lock that protects the transfer log. 696 * 697 * _req_add_to_epoch(req); this has to be after the 698 * _maybe_start_new_epoch(req); which happened in 699 * __drbd_make_request, because we now may set the bit 700 * again ourselves to close the current epoch. 701 * 702 * Add req to the (now) current epoch (barrier). */ 703 704 /* otherwise we may lose an unplug, which may cause some remote 705 * io-scheduler timeout to expire, increasing maximum latency, 706 * hurting performance. */ 707 set_bit(UNPLUG_REMOTE, &device->flags); 708 709 /* queue work item to send data */ 710 D_ASSERT(device, req->rq_state & RQ_NET_PENDING); 711 mod_rq_state(req, m, 0, RQ_NET_QUEUED|RQ_EXP_BARR_ACK); 712 req->w.cb = w_send_dblock; 713 drbd_queue_work(&connection->sender_work, 714 &req->w); 715 716 /* close the epoch, in case it outgrew the limit */ 717 rcu_read_lock(); 718 nc = rcu_dereference(connection->net_conf); 719 p = nc->max_epoch_size; 720 rcu_read_unlock(); 721 if (connection->current_tle_writes >= p) 722 start_new_tl_epoch(connection); 723 724 break; 725 726 case QUEUE_FOR_SEND_OOS: 727 mod_rq_state(req, m, 0, RQ_NET_QUEUED); 728 req->w.cb = w_send_out_of_sync; 729 drbd_queue_work(&connection->sender_work, 730 &req->w); 731 break; 732 733 case READ_RETRY_REMOTE_CANCELED: 734 case SEND_CANCELED: 735 case SEND_FAILED: 736 /* real cleanup will be done from tl_clear. just update flags 737 * so it is no longer marked as on the worker queue */ 738 mod_rq_state(req, m, RQ_NET_QUEUED, 0); 739 break; 740 741 case HANDED_OVER_TO_NETWORK: 742 /* assert something? */ 743 if (is_pending_write_protocol_A(req)) 744 /* this is what is dangerous about protocol A: 745 * pretend it was successfully written on the peer. */ 746 mod_rq_state(req, m, RQ_NET_QUEUED|RQ_NET_PENDING, 747 RQ_NET_SENT|RQ_NET_OK); 748 else 749 mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_SENT); 750 /* It is still not yet RQ_NET_DONE until the 751 * corresponding epoch barrier got acked as well, 752 * so we know what to dirty on connection loss. */ 753 break; 754 755 case OOS_HANDED_TO_NETWORK: 756 /* Was not set PENDING, no longer QUEUED, so is now DONE 757 * as far as this connection is concerned. */ 758 mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_DONE); 759 break; 760 761 case CONNECTION_LOST_WHILE_PENDING: 762 /* transfer log cleanup after connection loss */ 763 mod_rq_state(req, m, 764 RQ_NET_OK|RQ_NET_PENDING|RQ_COMPLETION_SUSP, 765 RQ_NET_DONE); 766 break; 767 768 case CONFLICT_RESOLVED: 769 /* for superseded conflicting writes of multiple primaries, 770 * there is no need to keep anything in the tl, potential 771 * node crashes are covered by the activity log. 772 * 773 * If this request had been marked as RQ_POSTPONED before, 774 * it will actually not be completed, but "restarted", 775 * resubmitted from the retry worker context. */ 776 D_ASSERT(device, req->rq_state & RQ_NET_PENDING); 777 D_ASSERT(device, req->rq_state & RQ_EXP_WRITE_ACK); 778 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_DONE|RQ_NET_OK); 779 break; 780 781 case WRITE_ACKED_BY_PEER_AND_SIS: 782 req->rq_state |= RQ_NET_SIS; 783 case WRITE_ACKED_BY_PEER: 784 /* Normal operation protocol C: successfully written on peer. 785 * During resync, even in protocol != C, 786 * we requested an explicit write ack anyways. 787 * Which means we cannot even assert anything here. 788 * Nothing more to do here. 789 * We want to keep the tl in place for all protocols, to cater 790 * for volatile write-back caches on lower level devices. */ 791 goto ack_common; 792 case RECV_ACKED_BY_PEER: 793 D_ASSERT(device, req->rq_state & RQ_EXP_RECEIVE_ACK); 794 /* protocol B; pretends to be successfully written on peer. 795 * see also notes above in HANDED_OVER_TO_NETWORK about 796 * protocol != C */ 797 ack_common: 798 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK); 799 break; 800 801 case POSTPONE_WRITE: 802 D_ASSERT(device, req->rq_state & RQ_EXP_WRITE_ACK); 803 /* If this node has already detected the write conflict, the 804 * worker will be waiting on misc_wait. Wake it up once this 805 * request has completed locally. 806 */ 807 D_ASSERT(device, req->rq_state & RQ_NET_PENDING); 808 req->rq_state |= RQ_POSTPONED; 809 if (req->i.waiting) 810 wake_up(&device->misc_wait); 811 /* Do not clear RQ_NET_PENDING. This request will make further 812 * progress via restart_conflicting_writes() or 813 * fail_postponed_requests(). Hopefully. */ 814 break; 815 816 case NEG_ACKED: 817 mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING, 0); 818 break; 819 820 case FAIL_FROZEN_DISK_IO: 821 if (!(req->rq_state & RQ_LOCAL_COMPLETED)) 822 break; 823 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0); 824 break; 825 826 case RESTART_FROZEN_DISK_IO: 827 if (!(req->rq_state & RQ_LOCAL_COMPLETED)) 828 break; 829 830 mod_rq_state(req, m, 831 RQ_COMPLETION_SUSP|RQ_LOCAL_COMPLETED, 832 RQ_LOCAL_PENDING); 833 834 rv = MR_READ; 835 if (bio_data_dir(req->master_bio) == WRITE) 836 rv = MR_WRITE; 837 838 get_ldev(device); /* always succeeds in this call path */ 839 req->w.cb = w_restart_disk_io; 840 drbd_queue_work(&connection->sender_work, 841 &req->w); 842 break; 843 844 case RESEND: 845 /* Simply complete (local only) READs. */ 846 if (!(req->rq_state & RQ_WRITE) && !req->w.cb) { 847 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0); 848 break; 849 } 850 851 /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK 852 before the connection loss (B&C only); only P_BARRIER_ACK 853 (or the local completion?) was missing when we suspended. 854 Throwing them out of the TL here by pretending we got a BARRIER_ACK. 855 During connection handshake, we ensure that the peer was not rebooted. */ 856 if (!(req->rq_state & RQ_NET_OK)) { 857 /* FIXME could this possibly be a req->dw.cb == w_send_out_of_sync? 858 * in that case we must not set RQ_NET_PENDING. */ 859 860 mod_rq_state(req, m, RQ_COMPLETION_SUSP, RQ_NET_QUEUED|RQ_NET_PENDING); 861 if (req->w.cb) { 862 /* w.cb expected to be w_send_dblock, or w_send_read_req */ 863 drbd_queue_work(&connection->sender_work, 864 &req->w); 865 rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ; 866 } /* else: FIXME can this happen? */ 867 break; 868 } 869 /* else, fall through to BARRIER_ACKED */ 870 871 case BARRIER_ACKED: 872 /* barrier ack for READ requests does not make sense */ 873 if (!(req->rq_state & RQ_WRITE)) 874 break; 875 876 if (req->rq_state & RQ_NET_PENDING) { 877 /* barrier came in before all requests were acked. 878 * this is bad, because if the connection is lost now, 879 * we won't be able to clean them up... */ 880 drbd_err(device, "FIXME (BARRIER_ACKED but pending)\n"); 881 } 882 /* Allowed to complete requests, even while suspended. 883 * As this is called for all requests within a matching epoch, 884 * we need to filter, and only set RQ_NET_DONE for those that 885 * have actually been on the wire. */ 886 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 887 (req->rq_state & RQ_NET_MASK) ? RQ_NET_DONE : 0); 888 break; 889 890 case DATA_RECEIVED: 891 D_ASSERT(device, req->rq_state & RQ_NET_PENDING); 892 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK|RQ_NET_DONE); 893 break; 894 895 case QUEUE_AS_DRBD_BARRIER: 896 start_new_tl_epoch(connection); 897 mod_rq_state(req, m, 0, RQ_NET_OK|RQ_NET_DONE); 898 break; 899 }; 900 901 return rv; 902 } 903 904 /* we may do a local read if: 905 * - we are consistent (of course), 906 * - or we are generally inconsistent, 907 * BUT we are still/already IN SYNC for this area. 908 * since size may be bigger than BM_BLOCK_SIZE, 909 * we may need to check several bits. 910 */ 911 static bool drbd_may_do_local_read(struct drbd_device *device, sector_t sector, int size) 912 { 913 unsigned long sbnr, ebnr; 914 sector_t esector, nr_sectors; 915 916 if (device->state.disk == D_UP_TO_DATE) 917 return true; 918 if (device->state.disk != D_INCONSISTENT) 919 return false; 920 esector = sector + (size >> 9) - 1; 921 nr_sectors = drbd_get_capacity(device->this_bdev); 922 D_ASSERT(device, sector < nr_sectors); 923 D_ASSERT(device, esector < nr_sectors); 924 925 sbnr = BM_SECT_TO_BIT(sector); 926 ebnr = BM_SECT_TO_BIT(esector); 927 928 return drbd_bm_count_bits(device, sbnr, ebnr) == 0; 929 } 930 931 static bool remote_due_to_read_balancing(struct drbd_device *device, sector_t sector, 932 enum drbd_read_balancing rbm) 933 { 934 struct backing_dev_info *bdi; 935 int stripe_shift; 936 937 switch (rbm) { 938 case RB_CONGESTED_REMOTE: 939 bdi = device->ldev->backing_bdev->bd_disk->queue->backing_dev_info; 940 return bdi_read_congested(bdi); 941 case RB_LEAST_PENDING: 942 return atomic_read(&device->local_cnt) > 943 atomic_read(&device->ap_pending_cnt) + atomic_read(&device->rs_pending_cnt); 944 case RB_32K_STRIPING: /* stripe_shift = 15 */ 945 case RB_64K_STRIPING: 946 case RB_128K_STRIPING: 947 case RB_256K_STRIPING: 948 case RB_512K_STRIPING: 949 case RB_1M_STRIPING: /* stripe_shift = 20 */ 950 stripe_shift = (rbm - RB_32K_STRIPING + 15); 951 return (sector >> (stripe_shift - 9)) & 1; 952 case RB_ROUND_ROBIN: 953 return test_and_change_bit(READ_BALANCE_RR, &device->flags); 954 case RB_PREFER_REMOTE: 955 return true; 956 case RB_PREFER_LOCAL: 957 default: 958 return false; 959 } 960 } 961 962 /* 963 * complete_conflicting_writes - wait for any conflicting write requests 964 * 965 * The write_requests tree contains all active write requests which we 966 * currently know about. Wait for any requests to complete which conflict with 967 * the new one. 968 * 969 * Only way out: remove the conflicting intervals from the tree. 970 */ 971 static void complete_conflicting_writes(struct drbd_request *req) 972 { 973 DEFINE_WAIT(wait); 974 struct drbd_device *device = req->device; 975 struct drbd_interval *i; 976 sector_t sector = req->i.sector; 977 int size = req->i.size; 978 979 for (;;) { 980 drbd_for_each_overlap(i, &device->write_requests, sector, size) { 981 /* Ignore, if already completed to upper layers. */ 982 if (i->completed) 983 continue; 984 /* Handle the first found overlap. After the schedule 985 * we have to restart the tree walk. */ 986 break; 987 } 988 if (!i) /* if any */ 989 break; 990 991 /* Indicate to wake up device->misc_wait on progress. */ 992 prepare_to_wait(&device->misc_wait, &wait, TASK_UNINTERRUPTIBLE); 993 i->waiting = true; 994 spin_unlock_irq(&device->resource->req_lock); 995 schedule(); 996 spin_lock_irq(&device->resource->req_lock); 997 } 998 finish_wait(&device->misc_wait, &wait); 999 } 1000 1001 /* called within req_lock */ 1002 static void maybe_pull_ahead(struct drbd_device *device) 1003 { 1004 struct drbd_connection *connection = first_peer_device(device)->connection; 1005 struct net_conf *nc; 1006 bool congested = false; 1007 enum drbd_on_congestion on_congestion; 1008 1009 rcu_read_lock(); 1010 nc = rcu_dereference(connection->net_conf); 1011 on_congestion = nc ? nc->on_congestion : OC_BLOCK; 1012 rcu_read_unlock(); 1013 if (on_congestion == OC_BLOCK || 1014 connection->agreed_pro_version < 96) 1015 return; 1016 1017 if (on_congestion == OC_PULL_AHEAD && device->state.conn == C_AHEAD) 1018 return; /* nothing to do ... */ 1019 1020 /* If I don't even have good local storage, we can not reasonably try 1021 * to pull ahead of the peer. We also need the local reference to make 1022 * sure device->act_log is there. 1023 */ 1024 if (!get_ldev_if_state(device, D_UP_TO_DATE)) 1025 return; 1026 1027 if (nc->cong_fill && 1028 atomic_read(&device->ap_in_flight) >= nc->cong_fill) { 1029 drbd_info(device, "Congestion-fill threshold reached\n"); 1030 congested = true; 1031 } 1032 1033 if (device->act_log->used >= nc->cong_extents) { 1034 drbd_info(device, "Congestion-extents threshold reached\n"); 1035 congested = true; 1036 } 1037 1038 if (congested) { 1039 /* start a new epoch for non-mirrored writes */ 1040 start_new_tl_epoch(first_peer_device(device)->connection); 1041 1042 if (on_congestion == OC_PULL_AHEAD) 1043 _drbd_set_state(_NS(device, conn, C_AHEAD), 0, NULL); 1044 else /*nc->on_congestion == OC_DISCONNECT */ 1045 _drbd_set_state(_NS(device, conn, C_DISCONNECTING), 0, NULL); 1046 } 1047 put_ldev(device); 1048 } 1049 1050 /* If this returns false, and req->private_bio is still set, 1051 * this should be submitted locally. 1052 * 1053 * If it returns false, but req->private_bio is not set, 1054 * we do not have access to good data :( 1055 * 1056 * Otherwise, this destroys req->private_bio, if any, 1057 * and returns true. 1058 */ 1059 static bool do_remote_read(struct drbd_request *req) 1060 { 1061 struct drbd_device *device = req->device; 1062 enum drbd_read_balancing rbm; 1063 1064 if (req->private_bio) { 1065 if (!drbd_may_do_local_read(device, 1066 req->i.sector, req->i.size)) { 1067 bio_put(req->private_bio); 1068 req->private_bio = NULL; 1069 put_ldev(device); 1070 } 1071 } 1072 1073 if (device->state.pdsk != D_UP_TO_DATE) 1074 return false; 1075 1076 if (req->private_bio == NULL) 1077 return true; 1078 1079 /* TODO: improve read balancing decisions, take into account drbd 1080 * protocol, pending requests etc. */ 1081 1082 rcu_read_lock(); 1083 rbm = rcu_dereference(device->ldev->disk_conf)->read_balancing; 1084 rcu_read_unlock(); 1085 1086 if (rbm == RB_PREFER_LOCAL && req->private_bio) 1087 return false; /* submit locally */ 1088 1089 if (remote_due_to_read_balancing(device, req->i.sector, rbm)) { 1090 if (req->private_bio) { 1091 bio_put(req->private_bio); 1092 req->private_bio = NULL; 1093 put_ldev(device); 1094 } 1095 return true; 1096 } 1097 1098 return false; 1099 } 1100 1101 bool drbd_should_do_remote(union drbd_dev_state s) 1102 { 1103 return s.pdsk == D_UP_TO_DATE || 1104 (s.pdsk >= D_INCONSISTENT && 1105 s.conn >= C_WF_BITMAP_T && 1106 s.conn < C_AHEAD); 1107 /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T. 1108 That is equivalent since before 96 IO was frozen in the C_WF_BITMAP* 1109 states. */ 1110 } 1111 1112 static bool drbd_should_send_out_of_sync(union drbd_dev_state s) 1113 { 1114 return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S; 1115 /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary 1116 since we enter state C_AHEAD only if proto >= 96 */ 1117 } 1118 1119 /* returns number of connections (== 1, for drbd 8.4) 1120 * expected to actually write this data, 1121 * which does NOT include those that we are L_AHEAD for. */ 1122 static int drbd_process_write_request(struct drbd_request *req) 1123 { 1124 struct drbd_device *device = req->device; 1125 int remote, send_oos; 1126 1127 remote = drbd_should_do_remote(device->state); 1128 send_oos = drbd_should_send_out_of_sync(device->state); 1129 1130 /* Need to replicate writes. Unless it is an empty flush, 1131 * which is better mapped to a DRBD P_BARRIER packet, 1132 * also for drbd wire protocol compatibility reasons. 1133 * If this was a flush, just start a new epoch. 1134 * Unless the current epoch was empty anyways, or we are not currently 1135 * replicating, in which case there is no point. */ 1136 if (unlikely(req->i.size == 0)) { 1137 /* The only size==0 bios we expect are empty flushes. */ 1138 D_ASSERT(device, req->master_bio->bi_opf & REQ_PREFLUSH); 1139 if (remote) 1140 _req_mod(req, QUEUE_AS_DRBD_BARRIER); 1141 return remote; 1142 } 1143 1144 if (!remote && !send_oos) 1145 return 0; 1146 1147 D_ASSERT(device, !(remote && send_oos)); 1148 1149 if (remote) { 1150 _req_mod(req, TO_BE_SENT); 1151 _req_mod(req, QUEUE_FOR_NET_WRITE); 1152 } else if (drbd_set_out_of_sync(device, req->i.sector, req->i.size)) 1153 _req_mod(req, QUEUE_FOR_SEND_OOS); 1154 1155 return remote; 1156 } 1157 1158 static void drbd_process_discard_req(struct drbd_request *req) 1159 { 1160 struct block_device *bdev = req->device->ldev->backing_bdev; 1161 1162 if (blkdev_issue_zeroout(bdev, req->i.sector, req->i.size >> 9, 1163 GFP_NOIO, 0)) 1164 req->private_bio->bi_status = BLK_STS_IOERR; 1165 bio_endio(req->private_bio); 1166 } 1167 1168 static void 1169 drbd_submit_req_private_bio(struct drbd_request *req) 1170 { 1171 struct drbd_device *device = req->device; 1172 struct bio *bio = req->private_bio; 1173 unsigned int type; 1174 1175 if (bio_op(bio) != REQ_OP_READ) 1176 type = DRBD_FAULT_DT_WR; 1177 else if (bio->bi_opf & REQ_RAHEAD) 1178 type = DRBD_FAULT_DT_RA; 1179 else 1180 type = DRBD_FAULT_DT_RD; 1181 1182 bio_set_dev(bio, device->ldev->backing_bdev); 1183 1184 /* State may have changed since we grabbed our reference on the 1185 * ->ldev member. Double check, and short-circuit to endio. 1186 * In case the last activity log transaction failed to get on 1187 * stable storage, and this is a WRITE, we may not even submit 1188 * this bio. */ 1189 if (get_ldev(device)) { 1190 if (drbd_insert_fault(device, type)) 1191 bio_io_error(bio); 1192 else if (bio_op(bio) == REQ_OP_WRITE_ZEROES || 1193 bio_op(bio) == REQ_OP_DISCARD) 1194 drbd_process_discard_req(req); 1195 else 1196 generic_make_request(bio); 1197 put_ldev(device); 1198 } else 1199 bio_io_error(bio); 1200 } 1201 1202 static void drbd_queue_write(struct drbd_device *device, struct drbd_request *req) 1203 { 1204 spin_lock_irq(&device->resource->req_lock); 1205 list_add_tail(&req->tl_requests, &device->submit.writes); 1206 list_add_tail(&req->req_pending_master_completion, 1207 &device->pending_master_completion[1 /* WRITE */]); 1208 spin_unlock_irq(&device->resource->req_lock); 1209 queue_work(device->submit.wq, &device->submit.worker); 1210 /* do_submit() may sleep internally on al_wait, too */ 1211 wake_up(&device->al_wait); 1212 } 1213 1214 /* returns the new drbd_request pointer, if the caller is expected to 1215 * drbd_send_and_submit() it (to save latency), or NULL if we queued the 1216 * request on the submitter thread. 1217 * Returns ERR_PTR(-ENOMEM) if we cannot allocate a drbd_request. 1218 */ 1219 static struct drbd_request * 1220 drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long start_jif) 1221 { 1222 const int rw = bio_data_dir(bio); 1223 struct drbd_request *req; 1224 1225 /* allocate outside of all locks; */ 1226 req = drbd_req_new(device, bio); 1227 if (!req) { 1228 dec_ap_bio(device); 1229 /* only pass the error to the upper layers. 1230 * if user cannot handle io errors, that's not our business. */ 1231 drbd_err(device, "could not kmalloc() req\n"); 1232 bio->bi_status = BLK_STS_RESOURCE; 1233 bio_endio(bio); 1234 return ERR_PTR(-ENOMEM); 1235 } 1236 req->start_jif = start_jif; 1237 1238 if (!get_ldev(device)) { 1239 bio_put(req->private_bio); 1240 req->private_bio = NULL; 1241 } 1242 1243 /* Update disk stats */ 1244 _drbd_start_io_acct(device, req); 1245 1246 /* process discards always from our submitter thread */ 1247 if ((bio_op(bio) & REQ_OP_WRITE_ZEROES) || 1248 (bio_op(bio) & REQ_OP_DISCARD)) 1249 goto queue_for_submitter_thread; 1250 1251 if (rw == WRITE && req->private_bio && req->i.size 1252 && !test_bit(AL_SUSPENDED, &device->flags)) { 1253 if (!drbd_al_begin_io_fastpath(device, &req->i)) 1254 goto queue_for_submitter_thread; 1255 req->rq_state |= RQ_IN_ACT_LOG; 1256 req->in_actlog_jif = jiffies; 1257 } 1258 return req; 1259 1260 queue_for_submitter_thread: 1261 atomic_inc(&device->ap_actlog_cnt); 1262 drbd_queue_write(device, req); 1263 return NULL; 1264 } 1265 1266 /* Require at least one path to current data. 1267 * We don't want to allow writes on C_STANDALONE D_INCONSISTENT: 1268 * We would not allow to read what was written, 1269 * we would not have bumped the data generation uuids, 1270 * we would cause data divergence for all the wrong reasons. 1271 * 1272 * If we don't see at least one D_UP_TO_DATE, we will fail this request, 1273 * which either returns EIO, or, if OND_SUSPEND_IO is set, suspends IO, 1274 * and queues for retry later. 1275 */ 1276 static bool may_do_writes(struct drbd_device *device) 1277 { 1278 const union drbd_dev_state s = device->state; 1279 return s.disk == D_UP_TO_DATE || s.pdsk == D_UP_TO_DATE; 1280 } 1281 1282 struct drbd_plug_cb { 1283 struct blk_plug_cb cb; 1284 struct drbd_request *most_recent_req; 1285 /* do we need more? */ 1286 }; 1287 1288 static void drbd_unplug(struct blk_plug_cb *cb, bool from_schedule) 1289 { 1290 struct drbd_plug_cb *plug = container_of(cb, struct drbd_plug_cb, cb); 1291 struct drbd_resource *resource = plug->cb.data; 1292 struct drbd_request *req = plug->most_recent_req; 1293 1294 kfree(cb); 1295 if (!req) 1296 return; 1297 1298 spin_lock_irq(&resource->req_lock); 1299 /* In case the sender did not process it yet, raise the flag to 1300 * have it followed with P_UNPLUG_REMOTE just after. */ 1301 req->rq_state |= RQ_UNPLUG; 1302 /* but also queue a generic unplug */ 1303 drbd_queue_unplug(req->device); 1304 kref_put(&req->kref, drbd_req_destroy); 1305 spin_unlock_irq(&resource->req_lock); 1306 } 1307 1308 static struct drbd_plug_cb* drbd_check_plugged(struct drbd_resource *resource) 1309 { 1310 /* A lot of text to say 1311 * return (struct drbd_plug_cb*)blk_check_plugged(); */ 1312 struct drbd_plug_cb *plug; 1313 struct blk_plug_cb *cb = blk_check_plugged(drbd_unplug, resource, sizeof(*plug)); 1314 1315 if (cb) 1316 plug = container_of(cb, struct drbd_plug_cb, cb); 1317 else 1318 plug = NULL; 1319 return plug; 1320 } 1321 1322 static void drbd_update_plug(struct drbd_plug_cb *plug, struct drbd_request *req) 1323 { 1324 struct drbd_request *tmp = plug->most_recent_req; 1325 /* Will be sent to some peer. 1326 * Remember to tag it with UNPLUG_REMOTE on unplug */ 1327 kref_get(&req->kref); 1328 plug->most_recent_req = req; 1329 if (tmp) 1330 kref_put(&tmp->kref, drbd_req_destroy); 1331 } 1332 1333 static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req) 1334 { 1335 struct drbd_resource *resource = device->resource; 1336 const int rw = bio_data_dir(req->master_bio); 1337 struct bio_and_error m = { NULL, }; 1338 bool no_remote = false; 1339 bool submit_private_bio = false; 1340 1341 spin_lock_irq(&resource->req_lock); 1342 if (rw == WRITE) { 1343 /* This may temporarily give up the req_lock, 1344 * but will re-aquire it before it returns here. 1345 * Needs to be before the check on drbd_suspended() */ 1346 complete_conflicting_writes(req); 1347 /* no more giving up req_lock from now on! */ 1348 1349 /* check for congestion, and potentially stop sending 1350 * full data updates, but start sending "dirty bits" only. */ 1351 maybe_pull_ahead(device); 1352 } 1353 1354 1355 if (drbd_suspended(device)) { 1356 /* push back and retry: */ 1357 req->rq_state |= RQ_POSTPONED; 1358 if (req->private_bio) { 1359 bio_put(req->private_bio); 1360 req->private_bio = NULL; 1361 put_ldev(device); 1362 } 1363 goto out; 1364 } 1365 1366 /* We fail READ early, if we can not serve it. 1367 * We must do this before req is registered on any lists. 1368 * Otherwise, drbd_req_complete() will queue failed READ for retry. */ 1369 if (rw != WRITE) { 1370 if (!do_remote_read(req) && !req->private_bio) 1371 goto nodata; 1372 } 1373 1374 /* which transfer log epoch does this belong to? */ 1375 req->epoch = atomic_read(&first_peer_device(device)->connection->current_tle_nr); 1376 1377 /* no point in adding empty flushes to the transfer log, 1378 * they are mapped to drbd barriers already. */ 1379 if (likely(req->i.size!=0)) { 1380 if (rw == WRITE) 1381 first_peer_device(device)->connection->current_tle_writes++; 1382 1383 list_add_tail(&req->tl_requests, &first_peer_device(device)->connection->transfer_log); 1384 } 1385 1386 if (rw == WRITE) { 1387 if (req->private_bio && !may_do_writes(device)) { 1388 bio_put(req->private_bio); 1389 req->private_bio = NULL; 1390 put_ldev(device); 1391 goto nodata; 1392 } 1393 if (!drbd_process_write_request(req)) 1394 no_remote = true; 1395 } else { 1396 /* We either have a private_bio, or we can read from remote. 1397 * Otherwise we had done the goto nodata above. */ 1398 if (req->private_bio == NULL) { 1399 _req_mod(req, TO_BE_SENT); 1400 _req_mod(req, QUEUE_FOR_NET_READ); 1401 } else 1402 no_remote = true; 1403 } 1404 1405 if (no_remote == false) { 1406 struct drbd_plug_cb *plug = drbd_check_plugged(resource); 1407 if (plug) 1408 drbd_update_plug(plug, req); 1409 } 1410 1411 /* If it took the fast path in drbd_request_prepare, add it here. 1412 * The slow path has added it already. */ 1413 if (list_empty(&req->req_pending_master_completion)) 1414 list_add_tail(&req->req_pending_master_completion, 1415 &device->pending_master_completion[rw == WRITE]); 1416 if (req->private_bio) { 1417 /* needs to be marked within the same spinlock */ 1418 req->pre_submit_jif = jiffies; 1419 list_add_tail(&req->req_pending_local, 1420 &device->pending_completion[rw == WRITE]); 1421 _req_mod(req, TO_BE_SUBMITTED); 1422 /* but we need to give up the spinlock to submit */ 1423 submit_private_bio = true; 1424 } else if (no_remote) { 1425 nodata: 1426 if (__ratelimit(&drbd_ratelimit_state)) 1427 drbd_err(device, "IO ERROR: neither local nor remote data, sector %llu+%u\n", 1428 (unsigned long long)req->i.sector, req->i.size >> 9); 1429 /* A write may have been queued for send_oos, however. 1430 * So we can not simply free it, we must go through drbd_req_put_completion_ref() */ 1431 } 1432 1433 out: 1434 drbd_req_put_completion_ref(req, &m, 1); 1435 spin_unlock_irq(&resource->req_lock); 1436 1437 /* Even though above is a kref_put(), this is safe. 1438 * As long as we still need to submit our private bio, 1439 * we hold a completion ref, and the request cannot disappear. 1440 * If however this request did not even have a private bio to submit 1441 * (e.g. remote read), req may already be invalid now. 1442 * That's why we cannot check on req->private_bio. */ 1443 if (submit_private_bio) 1444 drbd_submit_req_private_bio(req); 1445 if (m.bio) 1446 complete_master_bio(device, &m); 1447 } 1448 1449 void __drbd_make_request(struct drbd_device *device, struct bio *bio, unsigned long start_jif) 1450 { 1451 struct drbd_request *req = drbd_request_prepare(device, bio, start_jif); 1452 if (IS_ERR_OR_NULL(req)) 1453 return; 1454 drbd_send_and_submit(device, req); 1455 } 1456 1457 static void submit_fast_path(struct drbd_device *device, struct list_head *incoming) 1458 { 1459 struct blk_plug plug; 1460 struct drbd_request *req, *tmp; 1461 1462 blk_start_plug(&plug); 1463 list_for_each_entry_safe(req, tmp, incoming, tl_requests) { 1464 const int rw = bio_data_dir(req->master_bio); 1465 1466 if (rw == WRITE /* rw != WRITE should not even end up here! */ 1467 && req->private_bio && req->i.size 1468 && !test_bit(AL_SUSPENDED, &device->flags)) { 1469 if (!drbd_al_begin_io_fastpath(device, &req->i)) 1470 continue; 1471 1472 req->rq_state |= RQ_IN_ACT_LOG; 1473 req->in_actlog_jif = jiffies; 1474 atomic_dec(&device->ap_actlog_cnt); 1475 } 1476 1477 list_del_init(&req->tl_requests); 1478 drbd_send_and_submit(device, req); 1479 } 1480 blk_finish_plug(&plug); 1481 } 1482 1483 static bool prepare_al_transaction_nonblock(struct drbd_device *device, 1484 struct list_head *incoming, 1485 struct list_head *pending, 1486 struct list_head *later) 1487 { 1488 struct drbd_request *req; 1489 int wake = 0; 1490 int err; 1491 1492 spin_lock_irq(&device->al_lock); 1493 while ((req = list_first_entry_or_null(incoming, struct drbd_request, tl_requests))) { 1494 err = drbd_al_begin_io_nonblock(device, &req->i); 1495 if (err == -ENOBUFS) 1496 break; 1497 if (err == -EBUSY) 1498 wake = 1; 1499 if (err) 1500 list_move_tail(&req->tl_requests, later); 1501 else 1502 list_move_tail(&req->tl_requests, pending); 1503 } 1504 spin_unlock_irq(&device->al_lock); 1505 if (wake) 1506 wake_up(&device->al_wait); 1507 return !list_empty(pending); 1508 } 1509 1510 static void send_and_submit_pending(struct drbd_device *device, struct list_head *pending) 1511 { 1512 struct blk_plug plug; 1513 struct drbd_request *req; 1514 1515 blk_start_plug(&plug); 1516 while ((req = list_first_entry_or_null(pending, struct drbd_request, tl_requests))) { 1517 req->rq_state |= RQ_IN_ACT_LOG; 1518 req->in_actlog_jif = jiffies; 1519 atomic_dec(&device->ap_actlog_cnt); 1520 list_del_init(&req->tl_requests); 1521 drbd_send_and_submit(device, req); 1522 } 1523 blk_finish_plug(&plug); 1524 } 1525 1526 void do_submit(struct work_struct *ws) 1527 { 1528 struct drbd_device *device = container_of(ws, struct drbd_device, submit.worker); 1529 LIST_HEAD(incoming); /* from drbd_make_request() */ 1530 LIST_HEAD(pending); /* to be submitted after next AL-transaction commit */ 1531 LIST_HEAD(busy); /* blocked by resync requests */ 1532 1533 /* grab new incoming requests */ 1534 spin_lock_irq(&device->resource->req_lock); 1535 list_splice_tail_init(&device->submit.writes, &incoming); 1536 spin_unlock_irq(&device->resource->req_lock); 1537 1538 for (;;) { 1539 DEFINE_WAIT(wait); 1540 1541 /* move used-to-be-busy back to front of incoming */ 1542 list_splice_init(&busy, &incoming); 1543 submit_fast_path(device, &incoming); 1544 if (list_empty(&incoming)) 1545 break; 1546 1547 for (;;) { 1548 prepare_to_wait(&device->al_wait, &wait, TASK_UNINTERRUPTIBLE); 1549 1550 list_splice_init(&busy, &incoming); 1551 prepare_al_transaction_nonblock(device, &incoming, &pending, &busy); 1552 if (!list_empty(&pending)) 1553 break; 1554 1555 schedule(); 1556 1557 /* If all currently "hot" activity log extents are kept busy by 1558 * incoming requests, we still must not totally starve new 1559 * requests to "cold" extents. 1560 * Something left on &incoming means there had not been 1561 * enough update slots available, and the activity log 1562 * has been marked as "starving". 1563 * 1564 * Try again now, without looking for new requests, 1565 * effectively blocking all new requests until we made 1566 * at least _some_ progress with what we currently have. 1567 */ 1568 if (!list_empty(&incoming)) 1569 continue; 1570 1571 /* Nothing moved to pending, but nothing left 1572 * on incoming: all moved to busy! 1573 * Grab new and iterate. */ 1574 spin_lock_irq(&device->resource->req_lock); 1575 list_splice_tail_init(&device->submit.writes, &incoming); 1576 spin_unlock_irq(&device->resource->req_lock); 1577 } 1578 finish_wait(&device->al_wait, &wait); 1579 1580 /* If the transaction was full, before all incoming requests 1581 * had been processed, skip ahead to commit, and iterate 1582 * without splicing in more incoming requests from upper layers. 1583 * 1584 * Else, if all incoming have been processed, 1585 * they have become either "pending" (to be submitted after 1586 * next transaction commit) or "busy" (blocked by resync). 1587 * 1588 * Maybe more was queued, while we prepared the transaction? 1589 * Try to stuff those into this transaction as well. 1590 * Be strictly non-blocking here, 1591 * we already have something to commit. 1592 * 1593 * Commit if we don't make any more progres. 1594 */ 1595 1596 while (list_empty(&incoming)) { 1597 LIST_HEAD(more_pending); 1598 LIST_HEAD(more_incoming); 1599 bool made_progress; 1600 1601 /* It is ok to look outside the lock, 1602 * it's only an optimization anyways */ 1603 if (list_empty(&device->submit.writes)) 1604 break; 1605 1606 spin_lock_irq(&device->resource->req_lock); 1607 list_splice_tail_init(&device->submit.writes, &more_incoming); 1608 spin_unlock_irq(&device->resource->req_lock); 1609 1610 if (list_empty(&more_incoming)) 1611 break; 1612 1613 made_progress = prepare_al_transaction_nonblock(device, &more_incoming, &more_pending, &busy); 1614 1615 list_splice_tail_init(&more_pending, &pending); 1616 list_splice_tail_init(&more_incoming, &incoming); 1617 if (!made_progress) 1618 break; 1619 } 1620 1621 drbd_al_begin_io_commit(device); 1622 send_and_submit_pending(device, &pending); 1623 } 1624 } 1625 1626 blk_qc_t drbd_make_request(struct request_queue *q, struct bio *bio) 1627 { 1628 struct drbd_device *device = (struct drbd_device *) q->queuedata; 1629 unsigned long start_jif; 1630 1631 blk_queue_split(q, &bio); 1632 1633 start_jif = jiffies; 1634 1635 /* 1636 * what we "blindly" assume: 1637 */ 1638 D_ASSERT(device, IS_ALIGNED(bio->bi_iter.bi_size, 512)); 1639 1640 inc_ap_bio(device); 1641 __drbd_make_request(device, bio, start_jif); 1642 return BLK_QC_T_NONE; 1643 } 1644 1645 static bool net_timeout_reached(struct drbd_request *net_req, 1646 struct drbd_connection *connection, 1647 unsigned long now, unsigned long ent, 1648 unsigned int ko_count, unsigned int timeout) 1649 { 1650 struct drbd_device *device = net_req->device; 1651 1652 if (!time_after(now, net_req->pre_send_jif + ent)) 1653 return false; 1654 1655 if (time_in_range(now, connection->last_reconnect_jif, connection->last_reconnect_jif + ent)) 1656 return false; 1657 1658 if (net_req->rq_state & RQ_NET_PENDING) { 1659 drbd_warn(device, "Remote failed to finish a request within %ums > ko-count (%u) * timeout (%u * 0.1s)\n", 1660 jiffies_to_msecs(now - net_req->pre_send_jif), ko_count, timeout); 1661 return true; 1662 } 1663 1664 /* We received an ACK already (or are using protocol A), 1665 * but are waiting for the epoch closing barrier ack. 1666 * Check if we sent the barrier already. We should not blame the peer 1667 * for being unresponsive, if we did not even ask it yet. */ 1668 if (net_req->epoch == connection->send.current_epoch_nr) { 1669 drbd_warn(device, 1670 "We did not send a P_BARRIER for %ums > ko-count (%u) * timeout (%u * 0.1s); drbd kernel thread blocked?\n", 1671 jiffies_to_msecs(now - net_req->pre_send_jif), ko_count, timeout); 1672 return false; 1673 } 1674 1675 /* Worst case: we may have been blocked for whatever reason, then 1676 * suddenly are able to send a lot of requests (and epoch separating 1677 * barriers) in quick succession. 1678 * The timestamp of the net_req may be much too old and not correspond 1679 * to the sending time of the relevant unack'ed barrier packet, so 1680 * would trigger a spurious timeout. The latest barrier packet may 1681 * have a too recent timestamp to trigger the timeout, potentially miss 1682 * a timeout. Right now we don't have a place to conveniently store 1683 * these timestamps. 1684 * But in this particular situation, the application requests are still 1685 * completed to upper layers, DRBD should still "feel" responsive. 1686 * No need yet to kill this connection, it may still recover. 1687 * If not, eventually we will have queued enough into the network for 1688 * us to block. From that point of view, the timestamp of the last sent 1689 * barrier packet is relevant enough. 1690 */ 1691 if (time_after(now, connection->send.last_sent_barrier_jif + ent)) { 1692 drbd_warn(device, "Remote failed to answer a P_BARRIER (sent at %lu jif; now=%lu jif) within %ums > ko-count (%u) * timeout (%u * 0.1s)\n", 1693 connection->send.last_sent_barrier_jif, now, 1694 jiffies_to_msecs(now - connection->send.last_sent_barrier_jif), ko_count, timeout); 1695 return true; 1696 } 1697 return false; 1698 } 1699 1700 /* A request is considered timed out, if 1701 * - we have some effective timeout from the configuration, 1702 * with some state restrictions applied, 1703 * - the oldest request is waiting for a response from the network 1704 * resp. the local disk, 1705 * - the oldest request is in fact older than the effective timeout, 1706 * - the connection was established (resp. disk was attached) 1707 * for longer than the timeout already. 1708 * Note that for 32bit jiffies and very stable connections/disks, 1709 * we may have a wrap around, which is catched by 1710 * !time_in_range(now, last_..._jif, last_..._jif + timeout). 1711 * 1712 * Side effect: once per 32bit wrap-around interval, which means every 1713 * ~198 days with 250 HZ, we have a window where the timeout would need 1714 * to expire twice (worst case) to become effective. Good enough. 1715 */ 1716 1717 void request_timer_fn(struct timer_list *t) 1718 { 1719 struct drbd_device *device = from_timer(device, t, request_timer); 1720 struct drbd_connection *connection = first_peer_device(device)->connection; 1721 struct drbd_request *req_read, *req_write, *req_peer; /* oldest request */ 1722 struct net_conf *nc; 1723 unsigned long oldest_submit_jif; 1724 unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */ 1725 unsigned long now; 1726 unsigned int ko_count = 0, timeout = 0; 1727 1728 rcu_read_lock(); 1729 nc = rcu_dereference(connection->net_conf); 1730 if (nc && device->state.conn >= C_WF_REPORT_PARAMS) { 1731 ko_count = nc->ko_count; 1732 timeout = nc->timeout; 1733 } 1734 1735 if (get_ldev(device)) { /* implicit state.disk >= D_INCONSISTENT */ 1736 dt = rcu_dereference(device->ldev->disk_conf)->disk_timeout * HZ / 10; 1737 put_ldev(device); 1738 } 1739 rcu_read_unlock(); 1740 1741 1742 ent = timeout * HZ/10 * ko_count; 1743 et = min_not_zero(dt, ent); 1744 1745 if (!et) 1746 return; /* Recurring timer stopped */ 1747 1748 now = jiffies; 1749 nt = now + et; 1750 1751 spin_lock_irq(&device->resource->req_lock); 1752 req_read = list_first_entry_or_null(&device->pending_completion[0], struct drbd_request, req_pending_local); 1753 req_write = list_first_entry_or_null(&device->pending_completion[1], struct drbd_request, req_pending_local); 1754 1755 /* maybe the oldest request waiting for the peer is in fact still 1756 * blocking in tcp sendmsg. That's ok, though, that's handled via the 1757 * socket send timeout, requesting a ping, and bumping ko-count in 1758 * we_should_drop_the_connection(). 1759 */ 1760 1761 /* check the oldest request we did successfully sent, 1762 * but which is still waiting for an ACK. */ 1763 req_peer = connection->req_ack_pending; 1764 1765 /* if we don't have such request (e.g. protocoll A) 1766 * check the oldest requests which is still waiting on its epoch 1767 * closing barrier ack. */ 1768 if (!req_peer) 1769 req_peer = connection->req_not_net_done; 1770 1771 /* evaluate the oldest peer request only in one timer! */ 1772 if (req_peer && req_peer->device != device) 1773 req_peer = NULL; 1774 1775 /* do we have something to evaluate? */ 1776 if (req_peer == NULL && req_write == NULL && req_read == NULL) 1777 goto out; 1778 1779 oldest_submit_jif = 1780 (req_write && req_read) 1781 ? ( time_before(req_write->pre_submit_jif, req_read->pre_submit_jif) 1782 ? req_write->pre_submit_jif : req_read->pre_submit_jif ) 1783 : req_write ? req_write->pre_submit_jif 1784 : req_read ? req_read->pre_submit_jif : now; 1785 1786 if (ent && req_peer && net_timeout_reached(req_peer, connection, now, ent, ko_count, timeout)) 1787 _conn_request_state(connection, NS(conn, C_TIMEOUT), CS_VERBOSE | CS_HARD); 1788 1789 if (dt && oldest_submit_jif != now && 1790 time_after(now, oldest_submit_jif + dt) && 1791 !time_in_range(now, device->last_reattach_jif, device->last_reattach_jif + dt)) { 1792 drbd_warn(device, "Local backing device failed to meet the disk-timeout\n"); 1793 __drbd_chk_io_error(device, DRBD_FORCE_DETACH); 1794 } 1795 1796 /* Reschedule timer for the nearest not already expired timeout. 1797 * Fallback to now + min(effective network timeout, disk timeout). */ 1798 ent = (ent && req_peer && time_before(now, req_peer->pre_send_jif + ent)) 1799 ? req_peer->pre_send_jif + ent : now + et; 1800 dt = (dt && oldest_submit_jif != now && time_before(now, oldest_submit_jif + dt)) 1801 ? oldest_submit_jif + dt : now + et; 1802 nt = time_before(ent, dt) ? ent : dt; 1803 out: 1804 spin_unlock_irq(&device->resource->req_lock); 1805 mod_timer(&device->request_timer, nt); 1806 } 1807