drivers/block/drbd/drbd_req.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3    drbd_req.c
   4
   5    This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
   6
   7    Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
   8    Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
   9    Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
  10
  11
  12  */
  13
  14 #include <linux/module.h>
  15
  16 #include <linux/slab.h>
  17 #include <linux/drbd.h>
  18 #include "drbd_int.h"
  19 #include "drbd_req.h"
  20
  21
  22 static bool drbd_may_do_local_read(struct drbd_device *device, sector_t sector, int size);
  23
  24 static struct drbd_request *drbd_req_new(struct drbd_device *device, struct bio *bio_src)
  25 {
  26         struct drbd_request *req;
  27
  28         req = mempool_alloc(&drbd_request_mempool, GFP_NOIO);
  29         if (!req)
  30                 return NULL;
  31         memset(req, 0, sizeof(*req));
  32
  33         drbd_req_make_private_bio(req, bio_src);
  34         req->rq_state = (bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0)
  35                       | (bio_op(bio_src) == REQ_OP_WRITE_SAME ? RQ_WSAME : 0)
  36                       | (bio_op(bio_src) == REQ_OP_WRITE_ZEROES ? RQ_ZEROES : 0)
  37                       | (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 0);
  38         req->device = device;
  39         req->master_bio = bio_src;
  40         req->epoch = 0;
  41
  42         drbd_clear_interval(&req->i);
  43         req->i.sector     = bio_src->bi_iter.bi_sector;
  44         req->i.size      = bio_src->bi_iter.bi_size;
  45         req->i.local = true;
  46         req->i.waiting = false;
  47
  48         INIT_LIST_HEAD(&req->tl_requests);
  49         INIT_LIST_HEAD(&req->w.list);
  50         INIT_LIST_HEAD(&req->req_pending_master_completion);
  51         INIT_LIST_HEAD(&req->req_pending_local);
  52
  53         /* one reference to be put by __drbd_make_request */
  54         atomic_set(&req->completion_ref, 1);
  55         /* one kref as long as completion_ref > 0 */
  56         kref_init(&req->kref);
  57         return req;
  58 }
  59
  60 static void drbd_remove_request_interval(struct rb_root *root,
  61                                          struct drbd_request *req)
  62 {
  63         struct drbd_device *device = req->device;
  64         struct drbd_interval *i = &req->i;
  65
  66         drbd_remove_interval(root, i);
  67
  68         /* Wake up any processes waiting for this request to complete.  */
  69         if (i->waiting)
  70                 wake_up(&device->misc_wait);
  71 }
  72
  73 void drbd_req_destroy(struct kref *kref)
  74 {
  75         struct drbd_request *req = container_of(kref, struct drbd_request, kref);
  76         struct drbd_device *device = req->device;
  77         const unsigned s = req->rq_state;
  78
  79         if ((req->master_bio && !(s & RQ_POSTPONED)) ||
  80                 atomic_read(&req->completion_ref) ||
  81                 (s & RQ_LOCAL_PENDING) ||
  82                 ((s & RQ_NET_MASK) && !(s & RQ_NET_DONE))) {
  83                 drbd_err(device, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n",
  84                                 s, atomic_read(&req->completion_ref));
  85                 return;
  86         }
  87
  88         /* If called from mod_rq_state (expected normal case) or
  89          * drbd_send_and_submit (the less likely normal path), this holds the
  90          * req_lock, and req->tl_requests will typicaly be on ->transfer_log,
  91          * though it may be still empty (never added to the transfer log).
  92          *
  93          * If called from do_retry(), we do NOT hold the req_lock, but we are
  94          * still allowed to unconditionally list_del(&req->tl_requests),
  95          * because it will be on a local on-stack list only. */
  96         list_del_init(&req->tl_requests);
  97
  98         /* finally remove the request from the conflict detection
  99          * respective block_id verification interval tree. */
 100         if (!drbd_interval_empty(&req->i)) {
 101                 struct rb_root *root;
 102
 103                 if (s & RQ_WRITE)
 104                         root = &device->write_requests;
 105                 else
 106                         root = &device->read_requests;
 107                 drbd_remove_request_interval(root, req);
 108         } else if (s & (RQ_NET_MASK & ~RQ_NET_DONE) && req->i.size != 0)
 109                 drbd_err(device, "drbd_req_destroy: Logic BUG: interval empty, but: rq_state=0x%x, sect=%llu, size=%u\n",
 110                         s, (unsigned long long)req->i.sector, req->i.size);
 111
 112         /* if it was a write, we may have to set the corresponding
 113          * bit(s) out-of-sync first. If it had a local part, we need to
 114          * release the reference to the activity log. */
 115         if (s & RQ_WRITE) {
 116                 /* Set out-of-sync unless both OK flags are set
 117                  * (local only or remote failed).
 118                  * Other places where we set out-of-sync:
 119                  * READ with local io-error */
 120
 121                 /* There is a special case:
 122                  * we may notice late that IO was suspended,
 123                  * and postpone, or schedule for retry, a write,
 124                  * before it even was submitted or sent.
 125                  * In that case we do not want to touch the bitmap at all.
 126                  */
 127                 if ((s & (RQ_POSTPONED|RQ_LOCAL_MASK|RQ_NET_MASK)) != RQ_POSTPONED) {
 128                         if (!(s & RQ_NET_OK) || !(s & RQ_LOCAL_OK))
 129                                 drbd_set_out_of_sync(device, req->i.sector, req->i.size);
 130
 131                         if ((s & RQ_NET_OK) && (s & RQ_LOCAL_OK) && (s & RQ_NET_SIS))
 132                                 drbd_set_in_sync(device, req->i.sector, req->i.size);
 133                 }
 134
 135                 /* one might be tempted to move the drbd_al_complete_io
 136                  * to the local io completion callback drbd_request_endio.
 137                  * but, if this was a mirror write, we may only
 138                  * drbd_al_complete_io after this is RQ_NET_DONE,
 139                  * otherwise the extent could be dropped from the al
 140                  * before it has actually been written on the peer.
 141                  * if we crash before our peer knows about the request,
 142                  * but after the extent has been dropped from the al,
 143                  * we would forget to resync the corresponding extent.
 144                  */
 145                 if (s & RQ_IN_ACT_LOG) {
 146                         if (get_ldev_if_state(device, D_FAILED)) {
 147                                 drbd_al_complete_io(device, &req->i);
 148                                 put_ldev(device);
 149                         } else if (__ratelimit(&drbd_ratelimit_state)) {
 150                                 drbd_warn(device, "Should have called drbd_al_complete_io(, %llu, %u), "
 151                                          "but my Disk seems to have failed :(\n",
 152                                          (unsigned long long) req->i.sector, req->i.size);
 153                         }
 154                 }
 155         }
 156
 157         mempool_free(req, &drbd_request_mempool);
 158 }
 159
 160 static void wake_all_senders(struct drbd_connection *connection)
 161 {
 162         wake_up(&connection->sender_work.q_wait);
 163 }
 164
 165 /* must hold resource->req_lock */
 166 void start_new_tl_epoch(struct drbd_connection *connection)
 167 {
 168         /* no point closing an epoch, if it is empty, anyways. */
 169         if (connection->current_tle_writes == 0)
 170                 return;
 171
 172         connection->current_tle_writes = 0;
 173         atomic_inc(&connection->current_tle_nr);
 174         wake_all_senders(connection);
 175 }
 176
 177 void complete_master_bio(struct drbd_device *device,
 178                 struct bio_and_error *m)
 179 {
 180         if (unlikely(m->error))
 181                 m->bio->bi_status = errno_to_blk_status(m->error);
 182         bio_endio(m->bio);
 183         dec_ap_bio(device);
 184 }
 185
 186
 187 /* Helper for __req_mod().
 188  * Set m->bio to the master bio, if it is fit to be completed,
 189  * or leave it alone (it is initialized to NULL in __req_mod),
 190  * if it has already been completed, or cannot be completed yet.
 191  * If m->bio is set, the error status to be returned is placed in m->error.
 192  */
 193 static
 194 void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
 195 {
 196         const unsigned s = req->rq_state;
 197         struct drbd_device *device = req->device;
 198         int error, ok;
 199
 200         /* we must not complete the master bio, while it is
 201          *      still being processed by _drbd_send_zc_bio (drbd_send_dblock)
 202          *      not yet acknowledged by the peer
 203          *      not yet completed by the local io subsystem
 204          * these flags may get cleared in any order by
 205          *      the worker,
 206          *      the receiver,
 207          *      the bio_endio completion callbacks.
 208          */
 209         if ((s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED)) ||
 210             (s & RQ_NET_QUEUED) || (s & RQ_NET_PENDING) ||
 211             (s & RQ_COMPLETION_SUSP)) {
 212                 drbd_err(device, "drbd_req_complete: Logic BUG rq_state = 0x%x\n", s);
 213                 return;
 214         }
 215
 216         if (!req->master_bio) {
 217                 drbd_err(device, "drbd_req_complete: Logic BUG, master_bio == NULL!\n");
 218                 return;
 219         }
 220
 221         /*
 222          * figure out whether to report success or failure.
 223          *
 224          * report success when at least one of the operations succeeded.
 225          * or, to put the other way,
 226          * only report failure, when both operations failed.
 227          *
 228          * what to do about the failures is handled elsewhere.
 229          * what we need to do here is just: complete the master_bio.
 230          *
 231          * local completion error, if any, has been stored as ERR_PTR
 232          * in private_bio within drbd_request_endio.
 233          */
 234         ok = (s & RQ_LOCAL_OK) || (s & RQ_NET_OK);
 235         error = PTR_ERR(req->private_bio);
 236
 237         /* Before we can signal completion to the upper layers,
 238          * we may need to close the current transfer log epoch.
 239          * We are within the request lock, so we can simply compare
 240          * the request epoch number with the current transfer log
 241          * epoch number.  If they match, increase the current_tle_nr,
 242          * and reset the transfer log epoch write_cnt.
 243          */
 244         if (op_is_write(bio_op(req->master_bio)) &&
 245             req->epoch == atomic_read(&first_peer_device(device)->connection->current_tle_nr))
 246                 start_new_tl_epoch(first_peer_device(device)->connection);
 247
 248         /* Update disk stats */
 249         bio_end_io_acct(req->master_bio, req->start_jif);
 250
 251         /* If READ failed,
 252          * have it be pushed back to the retry work queue,
 253          * so it will re-enter __drbd_make_request(),
 254          * and be re-assigned to a suitable local or remote path,
 255          * or failed if we do not have access to good data anymore.
 256          *
 257          * Unless it was failed early by __drbd_make_request(),
 258          * because no path was available, in which case
 259          * it was not even added to the transfer_log.
 260          *
 261          * read-ahead may fail, and will not be retried.
 262          *
 263          * WRITE should have used all available paths already.
 264          */
 265         if (!ok &&
 266             bio_op(req->master_bio) == REQ_OP_READ &&
 267             !(req->master_bio->bi_opf & REQ_RAHEAD) &&
 268             !list_empty(&req->tl_requests))
 269                 req->rq_state |= RQ_POSTPONED;
 270
 271         if (!(req->rq_state & RQ_POSTPONED)) {
 272                 m->error = ok ? 0 : (error ?: -EIO);
 273                 m->bio = req->master_bio;
 274                 req->master_bio = NULL;
 275                 /* We leave it in the tree, to be able to verify later
 276                  * write-acks in protocol != C during resync.
 277                  * But we mark it as "complete", so it won't be counted as
 278                  * conflict in a multi-primary setup. */
 279                 req->i.completed = true;
 280         }
 281
 282         if (req->i.waiting)
 283                 wake_up(&device->misc_wait);
 284
 285         /* Either we are about to complete to upper layers,
 286          * or we will restart this request.
 287          * In either case, the request object will be destroyed soon,
 288          * so better remove it from all lists. */
 289         list_del_init(&req->req_pending_master_completion);
 290 }
 291
 292 /* still holds resource->req_lock */
 293 static void drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put)
 294 {
 295         struct drbd_device *device = req->device;
 296         D_ASSERT(device, m || (req->rq_state & RQ_POSTPONED));
 297
 298         if (!put)
 299                 return;
 300
 301         if (!atomic_sub_and_test(put, &req->completion_ref))
 302                 return;
 303
 304         drbd_req_complete(req, m);
 305
 306         /* local completion may still come in later,
 307          * we need to keep the req object around. */
 308         if (req->rq_state & RQ_LOCAL_ABORTED)
 309                 return;
 310
 311         if (req->rq_state & RQ_POSTPONED) {
 312                 /* don't destroy the req object just yet,
 313                  * but queue it for retry */
 314                 drbd_restart_request(req);
 315                 return;
 316         }
 317
 318         kref_put(&req->kref, drbd_req_destroy);
 319 }
 320
 321 static void set_if_null_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req)
 322 {
 323         struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
 324         if (!connection)
 325                 return;
 326         if (connection->req_next == NULL)
 327                 connection->req_next = req;
 328 }
 329
 330 static void advance_conn_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req)
 331 {
 332         struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
 333         if (!connection)
 334                 return;
 335         if (connection->req_next != req)
 336                 return;
 337         list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
 338                 const unsigned s = req->rq_state;
 339                 if (s & RQ_NET_QUEUED)
 340                         break;
 341         }
 342         if (&req->tl_requests == &connection->transfer_log)
 343                 req = NULL;
 344         connection->req_next = req;
 345 }
 346
 347 static void set_if_null_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req)
 348 {
 349         struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
 350         if (!connection)
 351                 return;
 352         if (connection->req_ack_pending == NULL)
 353                 connection->req_ack_pending = req;
 354 }
 355
 356 static void advance_conn_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req)
 357 {
 358         struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
 359         if (!connection)
 360                 return;
 361         if (connection->req_ack_pending != req)
 362                 return;
 363         list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
 364                 const unsigned s = req->rq_state;
 365                 if ((s & RQ_NET_SENT) && (s & RQ_NET_PENDING))
 366                         break;
 367         }
 368         if (&req->tl_requests == &connection->transfer_log)
 369                 req = NULL;
 370         connection->req_ack_pending = req;
 371 }
 372
 373 static void set_if_null_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req)
 374 {
 375         struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
 376         if (!connection)
 377                 return;
 378         if (connection->req_not_net_done == NULL)
 379                 connection->req_not_net_done = req;
 380 }
 381
 382 static void advance_conn_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req)
 383 {
 384         struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
 385         if (!connection)
 386                 return;
 387         if (connection->req_not_net_done != req)
 388                 return;
 389         list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
 390                 const unsigned s = req->rq_state;
 391                 if ((s & RQ_NET_SENT) && !(s & RQ_NET_DONE))
 392                         break;
 393         }
 394         if (&req->tl_requests == &connection->transfer_log)
 395                 req = NULL;
 396         connection->req_not_net_done = req;
 397 }
 398
 399 /* I'd like this to be the only place that manipulates
 400  * req->completion_ref and req->kref. */
 401 static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
 402                 int clear, int set)
 403 {
 404         struct drbd_device *device = req->device;
 405         struct drbd_peer_device *peer_device = first_peer_device(device);
 406         unsigned s = req->rq_state;
 407         int c_put = 0;
 408
 409         if (drbd_suspended(device) && !((s | clear) & RQ_COMPLETION_SUSP))
 410                 set |= RQ_COMPLETION_SUSP;
 411
 412         /* apply */
 413
 414         req->rq_state &= ~clear;
 415         req->rq_state |= set;
 416
 417         /* no change? */
 418         if (req->rq_state == s)
 419                 return;
 420
 421         /* intent: get references */
 422
 423         kref_get(&req->kref);
 424
 425         if (!(s & RQ_LOCAL_PENDING) && (set & RQ_LOCAL_PENDING))
 426                 atomic_inc(&req->completion_ref);
 427
 428         if (!(s & RQ_NET_PENDING) && (set & RQ_NET_PENDING)) {
 429                 inc_ap_pending(device);
 430                 atomic_inc(&req->completion_ref);
 431         }
 432
 433         if (!(s & RQ_NET_QUEUED) && (set & RQ_NET_QUEUED)) {
 434                 atomic_inc(&req->completion_ref);
 435                 set_if_null_req_next(peer_device, req);
 436         }
 437
 438         if (!(s & RQ_EXP_BARR_ACK) && (set & RQ_EXP_BARR_ACK))
 439                 kref_get(&req->kref); /* wait for the DONE */
 440
 441         if (!(s & RQ_NET_SENT) && (set & RQ_NET_SENT)) {
 442                 /* potentially already completed in the ack_receiver thread */
 443                 if (!(s & RQ_NET_DONE)) {
 444                         atomic_add(req->i.size >> 9, &device->ap_in_flight);
 445                         set_if_null_req_not_net_done(peer_device, req);
 446                 }
 447                 if (req->rq_state & RQ_NET_PENDING)
 448                         set_if_null_req_ack_pending(peer_device, req);
 449         }
 450
 451         if (!(s & RQ_COMPLETION_SUSP) && (set & RQ_COMPLETION_SUSP))
 452                 atomic_inc(&req->completion_ref);
 453
 454         /* progress: put references */
 455
 456         if ((s & RQ_COMPLETION_SUSP) && (clear & RQ_COMPLETION_SUSP))
 457                 ++c_put;
 458
 459         if (!(s & RQ_LOCAL_ABORTED) && (set & RQ_LOCAL_ABORTED)) {
 460                 D_ASSERT(device, req->rq_state & RQ_LOCAL_PENDING);
 461                 ++c_put;
 462         }
 463
 464         if ((s & RQ_LOCAL_PENDING) && (clear & RQ_LOCAL_PENDING)) {
 465                 if (req->rq_state & RQ_LOCAL_ABORTED)
 466                         kref_put(&req->kref, drbd_req_destroy);
 467                 else
 468                         ++c_put;
 469                 list_del_init(&req->req_pending_local);
 470         }
 471
 472         if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) {
 473                 dec_ap_pending(device);
 474                 ++c_put;
 475                 req->acked_jif = jiffies;
 476                 advance_conn_req_ack_pending(peer_device, req);
 477         }
 478
 479         if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED)) {
 480                 ++c_put;
 481                 advance_conn_req_next(peer_device, req);
 482         }
 483
 484         if (!(s & RQ_NET_DONE) && (set & RQ_NET_DONE)) {
 485                 if (s & RQ_NET_SENT)
 486                         atomic_sub(req->i.size >> 9, &device->ap_in_flight);
 487                 if (s & RQ_EXP_BARR_ACK)
 488                         kref_put(&req->kref, drbd_req_destroy);
 489                 req->net_done_jif = jiffies;
 490
 491                 /* in ahead/behind mode, or just in case,
 492                  * before we finally destroy this request,
 493                  * the caching pointers must not reference it anymore */
 494                 advance_conn_req_next(peer_device, req);
 495                 advance_conn_req_ack_pending(peer_device, req);
 496                 advance_conn_req_not_net_done(peer_device, req);
 497         }
 498
 499         /* potentially complete and destroy */
 500
 501         /* If we made progress, retry conflicting peer requests, if any. */
 502         if (req->i.waiting)
 503                 wake_up(&device->misc_wait);
 504
 505         drbd_req_put_completion_ref(req, m, c_put);
 506         kref_put(&req->kref, drbd_req_destroy);
 507 }
 508
 509 static void drbd_report_io_error(struct drbd_device *device, struct drbd_request *req)
 510 {
 511         char b[BDEVNAME_SIZE];
 512
 513         if (!__ratelimit(&drbd_ratelimit_state))
 514                 return;
 515
 516         drbd_warn(device, "local %s IO error sector %llu+%u on %s\n",
 517                         (req->rq_state & RQ_WRITE) ? "WRITE" : "READ",
 518                         (unsigned long long)req->i.sector,
 519                         req->i.size >> 9,
 520                         bdevname(device->ldev->backing_bdev, b));
 521 }
 522
 523 /* Helper for HANDED_OVER_TO_NETWORK.
 524  * Is this a protocol A write (neither WRITE_ACK nor RECEIVE_ACK expected)?
 525  * Is it also still "PENDING"?
 526  * --> If so, clear PENDING and set NET_OK below.
 527  * If it is a protocol A write, but not RQ_PENDING anymore, neg-ack was faster
 528  * (and we must not set RQ_NET_OK) */
 529 static inline bool is_pending_write_protocol_A(struct drbd_request *req)
 530 {
 531         return (req->rq_state &
 532                    (RQ_WRITE|RQ_NET_PENDING|RQ_EXP_WRITE_ACK|RQ_EXP_RECEIVE_ACK))
 533                 == (RQ_WRITE|RQ_NET_PENDING);
 534 }
 535
 536 /* obviously this could be coded as many single functions
 537  * instead of one huge switch,
 538  * or by putting the code directly in the respective locations
 539  * (as it has been before).
 540  *
 541  * but having it this way
 542  *  enforces that it is all in this one place, where it is easier to audit,
 543  *  it makes it obvious that whatever "event" "happens" to a request should
 544  *  happen "atomically" within the req_lock,
 545  *  and it enforces that we have to think in a very structured manner
 546  *  about the "events" that may happen to a request during its life time ...
 547  */
 548 int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 549                 struct bio_and_error *m)
 550 {
 551         struct drbd_device *const device = req->device;
 552         struct drbd_peer_device *const peer_device = first_peer_device(device);
 553         struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL;
 554         struct net_conf *nc;
 555         int p, rv = 0;
 556
 557         if (m)
 558                 m->bio = NULL;
 559
 560         switch (what) {
 561         default:
 562                 drbd_err(device, "LOGIC BUG in %s:%u\n", __FILE__ , __LINE__);
 563                 break;
 564
 565         /* does not happen...
 566          * initialization done in drbd_req_new
 567         case CREATED:
 568                 break;
 569                 */
 570
 571         case TO_BE_SENT: /* via network */
 572                 /* reached via __drbd_make_request
 573                  * and from w_read_retry_remote */
 574                 D_ASSERT(device, !(req->rq_state & RQ_NET_MASK));
 575                 rcu_read_lock();
 576                 nc = rcu_dereference(connection->net_conf);
 577                 p = nc->wire_protocol;
 578                 rcu_read_unlock();
 579                 req->rq_state |=
 580                         p == DRBD_PROT_C ? RQ_EXP_WRITE_ACK :
 581                         p == DRBD_PROT_B ? RQ_EXP_RECEIVE_ACK : 0;
 582                 mod_rq_state(req, m, 0, RQ_NET_PENDING);
 583                 break;
 584
 585         case TO_BE_SUBMITTED: /* locally */
 586                 /* reached via __drbd_make_request */
 587                 D_ASSERT(device, !(req->rq_state & RQ_LOCAL_MASK));
 588                 mod_rq_state(req, m, 0, RQ_LOCAL_PENDING);
 589                 break;
 590
 591         case COMPLETED_OK:
 592                 if (req->rq_state & RQ_WRITE)
 593                         device->writ_cnt += req->i.size >> 9;
 594                 else
 595                         device->read_cnt += req->i.size >> 9;
 596
 597                 mod_rq_state(req, m, RQ_LOCAL_PENDING,
 598                                 RQ_LOCAL_COMPLETED|RQ_LOCAL_OK);
 599                 break;
 600
 601         case ABORT_DISK_IO:
 602                 mod_rq_state(req, m, 0, RQ_LOCAL_ABORTED);
 603                 break;
 604
 605         case WRITE_COMPLETED_WITH_ERROR:
 606                 drbd_report_io_error(device, req);
 607                 __drbd_chk_io_error(device, DRBD_WRITE_ERROR);
 608                 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
 609                 break;
 610
 611         case READ_COMPLETED_WITH_ERROR:
 612                 drbd_set_out_of_sync(device, req->i.sector, req->i.size);
 613                 drbd_report_io_error(device, req);
 614                 __drbd_chk_io_error(device, DRBD_READ_ERROR);
 615                 fallthrough;
 616         case READ_AHEAD_COMPLETED_WITH_ERROR:
 617                 /* it is legal to fail read-ahead, no __drbd_chk_io_error in that case. */
 618                 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
 619                 break;
 620
 621         case DISCARD_COMPLETED_NOTSUPP:
 622         case DISCARD_COMPLETED_WITH_ERROR:
 623                 /* I'd rather not detach from local disk just because it
 624                  * failed a REQ_OP_DISCARD. */
 625                 mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
 626                 break;
 627
 628         case QUEUE_FOR_NET_READ:
 629                 /* READ, and
 630                  * no local disk,
 631                  * or target area marked as invalid,
 632                  * or just got an io-error. */
 633                 /* from __drbd_make_request
 634                  * or from bio_endio during read io-error recovery */
 635
 636                 /* So we can verify the handle in the answer packet.
 637                  * Corresponding drbd_remove_request_interval is in
 638                  * drbd_req_complete() */
 639                 D_ASSERT(device, drbd_interval_empty(&req->i));
 640                 drbd_insert_interval(&device->read_requests, &req->i);
 641
 642                 set_bit(UNPLUG_REMOTE, &device->flags);
 643
 644                 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
 645                 D_ASSERT(device, (req->rq_state & RQ_LOCAL_MASK) == 0);
 646                 mod_rq_state(req, m, 0, RQ_NET_QUEUED);
 647                 req->w.cb = w_send_read_req;
 648                 drbd_queue_work(&connection->sender_work,
 649                                 &req->w);
 650                 break;
 651
 652         case QUEUE_FOR_NET_WRITE:
 653                 /* assert something? */
 654                 /* from __drbd_make_request only */
 655
 656                 /* Corresponding drbd_remove_request_interval is in
 657                  * drbd_req_complete() */
 658                 D_ASSERT(device, drbd_interval_empty(&req->i));
 659                 drbd_insert_interval(&device->write_requests, &req->i);
 660
 661                 /* NOTE
 662                  * In case the req ended up on the transfer log before being
 663                  * queued on the worker, it could lead to this request being
 664                  * missed during cleanup after connection loss.
 665                  * So we have to do both operations here,
 666                  * within the same lock that protects the transfer log.
 667                  *
 668                  * _req_add_to_epoch(req); this has to be after the
 669                  * _maybe_start_new_epoch(req); which happened in
 670                  * __drbd_make_request, because we now may set the bit
 671                  * again ourselves to close the current epoch.
 672                  *
 673                  * Add req to the (now) current epoch (barrier). */
 674
 675                 /* otherwise we may lose an unplug, which may cause some remote
 676                  * io-scheduler timeout to expire, increasing maximum latency,
 677                  * hurting performance. */
 678                 set_bit(UNPLUG_REMOTE, &device->flags);
 679
 680                 /* queue work item to send data */
 681                 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
 682                 mod_rq_state(req, m, 0, RQ_NET_QUEUED|RQ_EXP_BARR_ACK);
 683                 req->w.cb =  w_send_dblock;
 684                 drbd_queue_work(&connection->sender_work,
 685                                 &req->w);
 686
 687                 /* close the epoch, in case it outgrew the limit */
 688                 rcu_read_lock();
 689                 nc = rcu_dereference(connection->net_conf);
 690                 p = nc->max_epoch_size;
 691                 rcu_read_unlock();
 692                 if (connection->current_tle_writes >= p)
 693                         start_new_tl_epoch(connection);
 694
 695                 break;
 696
 697         case QUEUE_FOR_SEND_OOS:
 698                 mod_rq_state(req, m, 0, RQ_NET_QUEUED);
 699                 req->w.cb =  w_send_out_of_sync;
 700                 drbd_queue_work(&connection->sender_work,
 701                                 &req->w);
 702                 break;
 703
 704         case READ_RETRY_REMOTE_CANCELED:
 705         case SEND_CANCELED:
 706         case SEND_FAILED:
 707                 /* real cleanup will be done from tl_clear.  just update flags
 708                  * so it is no longer marked as on the worker queue */
 709                 mod_rq_state(req, m, RQ_NET_QUEUED, 0);
 710                 break;
 711
 712         case HANDED_OVER_TO_NETWORK:
 713                 /* assert something? */
 714                 if (is_pending_write_protocol_A(req))
 715                         /* this is what is dangerous about protocol A:
 716                          * pretend it was successfully written on the peer. */
 717                         mod_rq_state(req, m, RQ_NET_QUEUED|RQ_NET_PENDING,
 718                                                 RQ_NET_SENT|RQ_NET_OK);
 719                 else
 720                         mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_SENT);
 721                 /* It is still not yet RQ_NET_DONE until the
 722                  * corresponding epoch barrier got acked as well,
 723                  * so we know what to dirty on connection loss. */
 724                 break;
 725
 726         case OOS_HANDED_TO_NETWORK:
 727                 /* Was not set PENDING, no longer QUEUED, so is now DONE
 728                  * as far as this connection is concerned. */
 729                 mod_rq_state(req, m, RQ_NET_QUEUED, RQ_NET_DONE);
 730                 break;
 731
 732         case CONNECTION_LOST_WHILE_PENDING:
 733                 /* transfer log cleanup after connection loss */
 734                 mod_rq_state(req, m,
 735                                 RQ_NET_OK|RQ_NET_PENDING|RQ_COMPLETION_SUSP,
 736                                 RQ_NET_DONE);
 737                 break;
 738
 739         case CONFLICT_RESOLVED:
 740                 /* for superseded conflicting writes of multiple primaries,
 741                  * there is no need to keep anything in the tl, potential
 742                  * node crashes are covered by the activity log.
 743                  *
 744                  * If this request had been marked as RQ_POSTPONED before,
 745                  * it will actually not be completed, but "restarted",
 746                  * resubmitted from the retry worker context. */
 747                 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
 748                 D_ASSERT(device, req->rq_state & RQ_EXP_WRITE_ACK);
 749                 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_DONE|RQ_NET_OK);
 750                 break;
 751
 752         case WRITE_ACKED_BY_PEER_AND_SIS:
 753                 req->rq_state |= RQ_NET_SIS;
 754         case WRITE_ACKED_BY_PEER:
 755                 /* Normal operation protocol C: successfully written on peer.
 756                  * During resync, even in protocol != C,
 757                  * we requested an explicit write ack anyways.
 758                  * Which means we cannot even assert anything here.
 759                  * Nothing more to do here.
 760                  * We want to keep the tl in place for all protocols, to cater
 761                  * for volatile write-back caches on lower level devices. */
 762                 goto ack_common;
 763         case RECV_ACKED_BY_PEER:
 764                 D_ASSERT(device, req->rq_state & RQ_EXP_RECEIVE_ACK);
 765                 /* protocol B; pretends to be successfully written on peer.
 766                  * see also notes above in HANDED_OVER_TO_NETWORK about
 767                  * protocol != C */
 768         ack_common:
 769                 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK);
 770                 break;
 771
 772         case POSTPONE_WRITE:
 773                 D_ASSERT(device, req->rq_state & RQ_EXP_WRITE_ACK);
 774                 /* If this node has already detected the write conflict, the
 775                  * worker will be waiting on misc_wait.  Wake it up once this
 776                  * request has completed locally.
 777                  */
 778                 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
 779                 req->rq_state |= RQ_POSTPONED;
 780                 if (req->i.waiting)
 781                         wake_up(&device->misc_wait);
 782                 /* Do not clear RQ_NET_PENDING. This request will make further
 783                  * progress via restart_conflicting_writes() or
 784                  * fail_postponed_requests(). Hopefully. */
 785                 break;
 786
 787         case NEG_ACKED:
 788                 mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING, 0);
 789                 break;
 790
 791         case FAIL_FROZEN_DISK_IO:
 792                 if (!(req->rq_state & RQ_LOCAL_COMPLETED))
 793                         break;
 794                 mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0);
 795                 break;
 796
 797         case RESTART_FROZEN_DISK_IO:
 798                 if (!(req->rq_state & RQ_LOCAL_COMPLETED))
 799                         break;
 800
 801                 mod_rq_state(req, m,
 802                                 RQ_COMPLETION_SUSP|RQ_LOCAL_COMPLETED,
 803                                 RQ_LOCAL_PENDING);
 804
 805                 rv = MR_READ;
 806                 if (bio_data_dir(req->master_bio) == WRITE)
 807                         rv = MR_WRITE;
 808
 809                 get_ldev(device); /* always succeeds in this call path */
 810                 req->w.cb = w_restart_disk_io;
 811                 drbd_queue_work(&connection->sender_work,
 812                                 &req->w);
 813                 break;
 814
 815         case RESEND:
 816                 /* Simply complete (local only) READs. */
 817                 if (!(req->rq_state & RQ_WRITE) && !req->w.cb) {
 818                         mod_rq_state(req, m, RQ_COMPLETION_SUSP, 0);
 819                         break;
 820                 }
 821
 822                 /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK
 823                    before the connection loss (B&C only); only P_BARRIER_ACK
 824                    (or the local completion?) was missing when we suspended.
 825                    Throwing them out of the TL here by pretending we got a BARRIER_ACK.
 826                    During connection handshake, we ensure that the peer was not rebooted. */
 827                 if (!(req->rq_state & RQ_NET_OK)) {
 828                         /* FIXME could this possibly be a req->dw.cb == w_send_out_of_sync?
 829                          * in that case we must not set RQ_NET_PENDING. */
 830
 831                         mod_rq_state(req, m, RQ_COMPLETION_SUSP, RQ_NET_QUEUED|RQ_NET_PENDING);
 832                         if (req->w.cb) {
 833                                 /* w.cb expected to be w_send_dblock, or w_send_read_req */
 834                                 drbd_queue_work(&connection->sender_work,
 835                                                 &req->w);
 836                                 rv = req->rq_state & RQ_WRITE ? MR_WRITE : MR_READ;
 837                         } /* else: FIXME can this happen? */
 838                         break;
 839                 }
 840                 fallthrough;    /* to BARRIER_ACKED */
 841
 842         case BARRIER_ACKED:
 843                 /* barrier ack for READ requests does not make sense */
 844                 if (!(req->rq_state & RQ_WRITE))
 845                         break;
 846
 847                 if (req->rq_state & RQ_NET_PENDING) {
 848                         /* barrier came in before all requests were acked.
 849                          * this is bad, because if the connection is lost now,
 850                          * we won't be able to clean them up... */
 851                         drbd_err(device, "FIXME (BARRIER_ACKED but pending)\n");
 852                 }
 853                 /* Allowed to complete requests, even while suspended.
 854                  * As this is called for all requests within a matching epoch,
 855                  * we need to filter, and only set RQ_NET_DONE for those that
 856                  * have actually been on the wire. */
 857                 mod_rq_state(req, m, RQ_COMPLETION_SUSP,
 858                                 (req->rq_state & RQ_NET_MASK) ? RQ_NET_DONE : 0);
 859                 break;
 860
 861         case DATA_RECEIVED:
 862                 D_ASSERT(device, req->rq_state & RQ_NET_PENDING);
 863                 mod_rq_state(req, m, RQ_NET_PENDING, RQ_NET_OK|RQ_NET_DONE);
 864                 break;
 865
 866         case QUEUE_AS_DRBD_BARRIER:
 867                 start_new_tl_epoch(connection);
 868                 mod_rq_state(req, m, 0, RQ_NET_OK|RQ_NET_DONE);
 869                 break;
 870         }
 871
 872         return rv;
 873 }
 874
 875 /* we may do a local read if:
 876  * - we are consistent (of course),
 877  * - or we are generally inconsistent,
 878  *   BUT we are still/already IN SYNC for this area.
 879  *   since size may be bigger than BM_BLOCK_SIZE,
 880  *   we may need to check several bits.
 881  */
 882 static bool drbd_may_do_local_read(struct drbd_device *device, sector_t sector, int size)
 883 {
 884         unsigned long sbnr, ebnr;
 885         sector_t esector, nr_sectors;
 886
 887         if (device->state.disk == D_UP_TO_DATE)
 888                 return true;
 889         if (device->state.disk != D_INCONSISTENT)
 890                 return false;
 891         esector = sector + (size >> 9) - 1;
 892         nr_sectors = get_capacity(device->vdisk);
 893         D_ASSERT(device, sector  < nr_sectors);
 894         D_ASSERT(device, esector < nr_sectors);
 895
 896         sbnr = BM_SECT_TO_BIT(sector);
 897         ebnr = BM_SECT_TO_BIT(esector);
 898
 899         return drbd_bm_count_bits(device, sbnr, ebnr) == 0;
 900 }
 901
 902 static bool remote_due_to_read_balancing(struct drbd_device *device, sector_t sector,
 903                 enum drbd_read_balancing rbm)
 904 {
 905         struct backing_dev_info *bdi;
 906         int stripe_shift;
 907
 908         switch (rbm) {
 909         case RB_CONGESTED_REMOTE:
 910                 bdi = device->ldev->backing_bdev->bd_disk->queue->backing_dev_info;
 911                 return bdi_read_congested(bdi);
 912         case RB_LEAST_PENDING:
 913                 return atomic_read(&device->local_cnt) >
 914                         atomic_read(&device->ap_pending_cnt) + atomic_read(&device->rs_pending_cnt);
 915         case RB_32K_STRIPING:  /* stripe_shift = 15 */
 916         case RB_64K_STRIPING:
 917         case RB_128K_STRIPING:
 918         case RB_256K_STRIPING:
 919         case RB_512K_STRIPING:
 920         case RB_1M_STRIPING:   /* stripe_shift = 20 */
 921                 stripe_shift = (rbm - RB_32K_STRIPING + 15);
 922                 return (sector >> (stripe_shift - 9)) & 1;
 923         case RB_ROUND_ROBIN:
 924                 return test_and_change_bit(READ_BALANCE_RR, &device->flags);
 925         case RB_PREFER_REMOTE:
 926                 return true;
 927         case RB_PREFER_LOCAL:
 928         default:
 929                 return false;
 930         }
 931 }
 932
 933 /*
 934  * complete_conflicting_writes  -  wait for any conflicting write requests
 935  *
 936  * The write_requests tree contains all active write requests which we
 937  * currently know about.  Wait for any requests to complete which conflict with
 938  * the new one.
 939  *
 940  * Only way out: remove the conflicting intervals from the tree.
 941  */
 942 static void complete_conflicting_writes(struct drbd_request *req)
 943 {
 944         DEFINE_WAIT(wait);
 945         struct drbd_device *device = req->device;
 946         struct drbd_interval *i;
 947         sector_t sector = req->i.sector;
 948         int size = req->i.size;
 949
 950         for (;;) {
 951                 drbd_for_each_overlap(i, &device->write_requests, sector, size) {
 952                         /* Ignore, if already completed to upper layers. */
 953                         if (i->completed)
 954                                 continue;
 955                         /* Handle the first found overlap.  After the schedule
 956                          * we have to restart the tree walk. */
 957                         break;
 958                 }
 959                 if (!i) /* if any */
 960                         break;
 961
 962                 /* Indicate to wake up device->misc_wait on progress.  */
 963                 prepare_to_wait(&device->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
 964                 i->waiting = true;
 965                 spin_unlock_irq(&device->resource->req_lock);
 966                 schedule();
 967                 spin_lock_irq(&device->resource->req_lock);
 968         }
 969         finish_wait(&device->misc_wait, &wait);
 970 }
 971
 972 /* called within req_lock */
 973 static void maybe_pull_ahead(struct drbd_device *device)
 974 {
 975         struct drbd_connection *connection = first_peer_device(device)->connection;
 976         struct net_conf *nc;
 977         bool congested = false;
 978         enum drbd_on_congestion on_congestion;
 979
 980         rcu_read_lock();
 981         nc = rcu_dereference(connection->net_conf);
 982         on_congestion = nc ? nc->on_congestion : OC_BLOCK;
 983         rcu_read_unlock();
 984         if (on_congestion == OC_BLOCK ||
 985             connection->agreed_pro_version < 96)
 986                 return;
 987
 988         if (on_congestion == OC_PULL_AHEAD && device->state.conn == C_AHEAD)
 989                 return; /* nothing to do ... */
 990
 991         /* If I don't even have good local storage, we can not reasonably try
 992          * to pull ahead of the peer. We also need the local reference to make
 993          * sure device->act_log is there.
 994          */
 995         if (!get_ldev_if_state(device, D_UP_TO_DATE))
 996                 return;
 997
 998         if (nc->cong_fill &&
 999             atomic_read(&device->ap_in_flight) >= nc->cong_fill) {
1000                 drbd_info(device, "Congestion-fill threshold reached\n");
1001                 congested = true;
1002         }
1003
1004         if (device->act_log->used >= nc->cong_extents) {
1005                 drbd_info(device, "Congestion-extents threshold reached\n");
1006                 congested = true;
1007         }
1008
1009         if (congested) {
1010                 /* start a new epoch for non-mirrored writes */
1011                 start_new_tl_epoch(first_peer_device(device)->connection);
1012
1013                 if (on_congestion == OC_PULL_AHEAD)
1014                         _drbd_set_state(_NS(device, conn, C_AHEAD), 0, NULL);
1015                 else  /*nc->on_congestion == OC_DISCONNECT */
1016                         _drbd_set_state(_NS(device, conn, C_DISCONNECTING), 0, NULL);
1017         }
1018         put_ldev(device);
1019 }
1020
1021 /* If this returns false, and req->private_bio is still set,
1022  * this should be submitted locally.
1023  *
1024  * If it returns false, but req->private_bio is not set,
1025  * we do not have access to good data :(
1026  *
1027  * Otherwise, this destroys req->private_bio, if any,
1028  * and returns true.
1029  */
1030 static bool do_remote_read(struct drbd_request *req)
1031 {
1032         struct drbd_device *device = req->device;
1033         enum drbd_read_balancing rbm;
1034
1035         if (req->private_bio) {
1036                 if (!drbd_may_do_local_read(device,
1037                                         req->i.sector, req->i.size)) {
1038                         bio_put(req->private_bio);
1039                         req->private_bio = NULL;
1040                         put_ldev(device);
1041                 }
1042         }
1043
1044         if (device->state.pdsk != D_UP_TO_DATE)
1045                 return false;
1046
1047         if (req->private_bio == NULL)
1048                 return true;
1049
1050         /* TODO: improve read balancing decisions, take into account drbd
1051          * protocol, pending requests etc. */
1052
1053         rcu_read_lock();
1054         rbm = rcu_dereference(device->ldev->disk_conf)->read_balancing;
1055         rcu_read_unlock();
1056
1057         if (rbm == RB_PREFER_LOCAL && req->private_bio)
1058                 return false; /* submit locally */
1059
1060         if (remote_due_to_read_balancing(device, req->i.sector, rbm)) {
1061                 if (req->private_bio) {
1062                         bio_put(req->private_bio);
1063                         req->private_bio = NULL;
1064                         put_ldev(device);
1065                 }
1066                 return true;
1067         }
1068
1069         return false;
1070 }
1071
1072 bool drbd_should_do_remote(union drbd_dev_state s)
1073 {
1074         return s.pdsk == D_UP_TO_DATE ||
1075                 (s.pdsk >= D_INCONSISTENT &&
1076                  s.conn >= C_WF_BITMAP_T &&
1077                  s.conn < C_AHEAD);
1078         /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T.
1079            That is equivalent since before 96 IO was frozen in the C_WF_BITMAP*
1080            states. */
1081 }
1082
1083 static bool drbd_should_send_out_of_sync(union drbd_dev_state s)
1084 {
1085         return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S;
1086         /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary
1087            since we enter state C_AHEAD only if proto >= 96 */
1088 }
1089
1090 /* returns number of connections (== 1, for drbd 8.4)
1091  * expected to actually write this data,
1092  * which does NOT include those that we are L_AHEAD for. */
1093 static int drbd_process_write_request(struct drbd_request *req)
1094 {
1095         struct drbd_device *device = req->device;
1096         int remote, send_oos;
1097
1098         remote = drbd_should_do_remote(device->state);
1099         send_oos = drbd_should_send_out_of_sync(device->state);
1100
1101         /* Need to replicate writes.  Unless it is an empty flush,
1102          * which is better mapped to a DRBD P_BARRIER packet,
1103          * also for drbd wire protocol compatibility reasons.
1104          * If this was a flush, just start a new epoch.
1105          * Unless the current epoch was empty anyways, or we are not currently
1106          * replicating, in which case there is no point. */
1107         if (unlikely(req->i.size == 0)) {
1108                 /* The only size==0 bios we expect are empty flushes. */
1109                 D_ASSERT(device, req->master_bio->bi_opf & REQ_PREFLUSH);
1110                 if (remote)
1111                         _req_mod(req, QUEUE_AS_DRBD_BARRIER);
1112                 return remote;
1113         }
1114
1115         if (!remote && !send_oos)
1116                 return 0;
1117
1118         D_ASSERT(device, !(remote && send_oos));
1119
1120         if (remote) {
1121                 _req_mod(req, TO_BE_SENT);
1122                 _req_mod(req, QUEUE_FOR_NET_WRITE);
1123         } else if (drbd_set_out_of_sync(device, req->i.sector, req->i.size))
1124                 _req_mod(req, QUEUE_FOR_SEND_OOS);
1125
1126         return remote;
1127 }
1128
1129 static void drbd_process_discard_or_zeroes_req(struct drbd_request *req, int flags)
1130 {
1131         int err = drbd_issue_discard_or_zero_out(req->device,
1132                                 req->i.sector, req->i.size >> 9, flags);
1133         if (err)
1134                 req->private_bio->bi_status = BLK_STS_IOERR;
1135         bio_endio(req->private_bio);
1136 }
1137
1138 static void
1139 drbd_submit_req_private_bio(struct drbd_request *req)
1140 {
1141         struct drbd_device *device = req->device;
1142         struct bio *bio = req->private_bio;
1143         unsigned int type;
1144
1145         if (bio_op(bio) != REQ_OP_READ)
1146                 type = DRBD_FAULT_DT_WR;
1147         else if (bio->bi_opf & REQ_RAHEAD)
1148                 type = DRBD_FAULT_DT_RA;
1149         else
1150                 type = DRBD_FAULT_DT_RD;
1151
1152         bio_set_dev(bio, device->ldev->backing_bdev);
1153
1154         /* State may have changed since we grabbed our reference on the
1155          * ->ldev member. Double check, and short-circuit to endio.
1156          * In case the last activity log transaction failed to get on
1157          * stable storage, and this is a WRITE, we may not even submit
1158          * this bio. */
1159         if (get_ldev(device)) {
1160                 if (drbd_insert_fault(device, type))
1161                         bio_io_error(bio);
1162                 else if (bio_op(bio) == REQ_OP_WRITE_ZEROES)
1163                         drbd_process_discard_or_zeroes_req(req, EE_ZEROOUT |
1164                             ((bio->bi_opf & REQ_NOUNMAP) ? 0 : EE_TRIM));
1165                 else if (bio_op(bio) == REQ_OP_DISCARD)
1166                         drbd_process_discard_or_zeroes_req(req, EE_TRIM);
1167                 else
1168                         submit_bio_noacct(bio);
1169                 put_ldev(device);
1170         } else
1171                 bio_io_error(bio);
1172 }
1173
1174 static void drbd_queue_write(struct drbd_device *device, struct drbd_request *req)
1175 {
1176         spin_lock_irq(&device->resource->req_lock);
1177         list_add_tail(&req->tl_requests, &device->submit.writes);
1178         list_add_tail(&req->req_pending_master_completion,
1179                         &device->pending_master_completion[1 /* WRITE */]);
1180         spin_unlock_irq(&device->resource->req_lock);
1181         queue_work(device->submit.wq, &device->submit.worker);
1182         /* do_submit() may sleep internally on al_wait, too */
1183         wake_up(&device->al_wait);
1184 }
1185
1186 /* returns the new drbd_request pointer, if the caller is expected to
1187  * drbd_send_and_submit() it (to save latency), or NULL if we queued the
1188  * request on the submitter thread.
1189  * Returns ERR_PTR(-ENOMEM) if we cannot allocate a drbd_request.
1190  */
1191 static struct drbd_request *
1192 drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long start_jif)
1193 {
1194         const int rw = bio_data_dir(bio);
1195         struct drbd_request *req;
1196
1197         /* allocate outside of all locks; */
1198         req = drbd_req_new(device, bio);
1199         if (!req) {
1200                 dec_ap_bio(device);
1201                 /* only pass the error to the upper layers.
1202                  * if user cannot handle io errors, that's not our business. */
1203                 drbd_err(device, "could not kmalloc() req\n");
1204                 bio->bi_status = BLK_STS_RESOURCE;
1205                 bio_endio(bio);
1206                 return ERR_PTR(-ENOMEM);
1207         }
1208
1209         /* Update disk stats */
1210         req->start_jif = bio_start_io_acct(req->master_bio);
1211
1212         if (!get_ldev(device)) {
1213                 bio_put(req->private_bio);
1214                 req->private_bio = NULL;
1215         }
1216
1217         /* process discards always from our submitter thread */
1218         if (bio_op(bio) == REQ_OP_WRITE_ZEROES ||
1219             bio_op(bio) == REQ_OP_DISCARD)
1220                 goto queue_for_submitter_thread;
1221
1222         if (rw == WRITE && req->private_bio && req->i.size
1223         && !test_bit(AL_SUSPENDED, &device->flags)) {
1224                 if (!drbd_al_begin_io_fastpath(device, &req->i))
1225                         goto queue_for_submitter_thread;
1226                 req->rq_state |= RQ_IN_ACT_LOG;
1227                 req->in_actlog_jif = jiffies;
1228         }
1229         return req;
1230
1231  queue_for_submitter_thread:
1232         atomic_inc(&device->ap_actlog_cnt);
1233         drbd_queue_write(device, req);
1234         return NULL;
1235 }
1236
1237 /* Require at least one path to current data.
1238  * We don't want to allow writes on C_STANDALONE D_INCONSISTENT:
1239  * We would not allow to read what was written,
1240  * we would not have bumped the data generation uuids,
1241  * we would cause data divergence for all the wrong reasons.
1242  *
1243  * If we don't see at least one D_UP_TO_DATE, we will fail this request,
1244  * which either returns EIO, or, if OND_SUSPEND_IO is set, suspends IO,
1245  * and queues for retry later.
1246  */
1247 static bool may_do_writes(struct drbd_device *device)
1248 {
1249         const union drbd_dev_state s = device->state;
1250         return s.disk == D_UP_TO_DATE || s.pdsk == D_UP_TO_DATE;
1251 }
1252
1253 struct drbd_plug_cb {
1254         struct blk_plug_cb cb;
1255         struct drbd_request *most_recent_req;
1256         /* do we need more? */
1257 };
1258
1259 static void drbd_unplug(struct blk_plug_cb *cb, bool from_schedule)
1260 {
1261         struct drbd_plug_cb *plug = container_of(cb, struct drbd_plug_cb, cb);
1262         struct drbd_resource *resource = plug->cb.data;
1263         struct drbd_request *req = plug->most_recent_req;
1264
1265         kfree(cb);
1266         if (!req)
1267                 return;
1268
1269         spin_lock_irq(&resource->req_lock);
1270         /* In case the sender did not process it yet, raise the flag to
1271          * have it followed with P_UNPLUG_REMOTE just after. */
1272         req->rq_state |= RQ_UNPLUG;
1273         /* but also queue a generic unplug */
1274         drbd_queue_unplug(req->device);
1275         kref_put(&req->kref, drbd_req_destroy);
1276         spin_unlock_irq(&resource->req_lock);
1277 }
1278
1279 static struct drbd_plug_cb* drbd_check_plugged(struct drbd_resource *resource)
1280 {
1281         /* A lot of text to say
1282          * return (struct drbd_plug_cb*)blk_check_plugged(); */
1283         struct drbd_plug_cb *plug;
1284         struct blk_plug_cb *cb = blk_check_plugged(drbd_unplug, resource, sizeof(*plug));
1285
1286         if (cb)
1287                 plug = container_of(cb, struct drbd_plug_cb, cb);
1288         else
1289                 plug = NULL;
1290         return plug;
1291 }
1292
1293 static void drbd_update_plug(struct drbd_plug_cb *plug, struct drbd_request *req)
1294 {
1295         struct drbd_request *tmp = plug->most_recent_req;
1296         /* Will be sent to some peer.
1297          * Remember to tag it with UNPLUG_REMOTE on unplug */
1298         kref_get(&req->kref);
1299         plug->most_recent_req = req;
1300         if (tmp)
1301                 kref_put(&tmp->kref, drbd_req_destroy);
1302 }
1303
1304 static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req)
1305 {
1306         struct drbd_resource *resource = device->resource;
1307         const int rw = bio_data_dir(req->master_bio);
1308         struct bio_and_error m = { NULL, };
1309         bool no_remote = false;
1310         bool submit_private_bio = false;
1311
1312         spin_lock_irq(&resource->req_lock);
1313         if (rw == WRITE) {
1314                 /* This may temporarily give up the req_lock,
1315                  * but will re-aquire it before it returns here.
1316                  * Needs to be before the check on drbd_suspended() */
1317                 complete_conflicting_writes(req);
1318                 /* no more giving up req_lock from now on! */
1319
1320                 /* check for congestion, and potentially stop sending
1321                  * full data updates, but start sending "dirty bits" only. */
1322                 maybe_pull_ahead(device);
1323         }
1324
1325
1326         if (drbd_suspended(device)) {
1327                 /* push back and retry: */
1328                 req->rq_state |= RQ_POSTPONED;
1329                 if (req->private_bio) {
1330                         bio_put(req->private_bio);
1331                         req->private_bio = NULL;
1332                         put_ldev(device);
1333                 }
1334                 goto out;
1335         }
1336
1337         /* We fail READ early, if we can not serve it.
1338          * We must do this before req is registered on any lists.
1339          * Otherwise, drbd_req_complete() will queue failed READ for retry. */
1340         if (rw != WRITE) {
1341                 if (!do_remote_read(req) && !req->private_bio)
1342                         goto nodata;
1343         }
1344
1345         /* which transfer log epoch does this belong to? */
1346         req->epoch = atomic_read(&first_peer_device(device)->connection->current_tle_nr);
1347
1348         /* no point in adding empty flushes to the transfer log,
1349          * they are mapped to drbd barriers already. */
1350         if (likely(req->i.size!=0)) {
1351                 if (rw == WRITE)
1352                         first_peer_device(device)->connection->current_tle_writes++;
1353
1354                 list_add_tail(&req->tl_requests, &first_peer_device(device)->connection->transfer_log);
1355         }
1356
1357         if (rw == WRITE) {
1358                 if (req->private_bio && !may_do_writes(device)) {
1359                         bio_put(req->private_bio);
1360                         req->private_bio = NULL;
1361                         put_ldev(device);
1362                         goto nodata;
1363                 }
1364                 if (!drbd_process_write_request(req))
1365                         no_remote = true;
1366         } else {
1367                 /* We either have a private_bio, or we can read from remote.
1368                  * Otherwise we had done the goto nodata above. */
1369                 if (req->private_bio == NULL) {
1370                         _req_mod(req, TO_BE_SENT);
1371                         _req_mod(req, QUEUE_FOR_NET_READ);
1372                 } else
1373                         no_remote = true;
1374         }
1375
1376         if (no_remote == false) {
1377                 struct drbd_plug_cb *plug = drbd_check_plugged(resource);
1378                 if (plug)
1379                         drbd_update_plug(plug, req);
1380         }
1381
1382         /* If it took the fast path in drbd_request_prepare, add it here.
1383          * The slow path has added it already. */
1384         if (list_empty(&req->req_pending_master_completion))
1385                 list_add_tail(&req->req_pending_master_completion,
1386                         &device->pending_master_completion[rw == WRITE]);
1387         if (req->private_bio) {
1388                 /* needs to be marked within the same spinlock */
1389                 req->pre_submit_jif = jiffies;
1390                 list_add_tail(&req->req_pending_local,
1391                         &device->pending_completion[rw == WRITE]);
1392                 _req_mod(req, TO_BE_SUBMITTED);
1393                 /* but we need to give up the spinlock to submit */
1394                 submit_private_bio = true;
1395         } else if (no_remote) {
1396 nodata:
1397                 if (__ratelimit(&drbd_ratelimit_state))
1398                         drbd_err(device, "IO ERROR: neither local nor remote data, sector %llu+%u\n",
1399                                         (unsigned long long)req->i.sector, req->i.size >> 9);
1400                 /* A write may have been queued for send_oos, however.
1401                  * So we can not simply free it, we must go through drbd_req_put_completion_ref() */
1402         }
1403
1404 out:
1405         drbd_req_put_completion_ref(req, &m, 1);
1406         spin_unlock_irq(&resource->req_lock);
1407
1408         /* Even though above is a kref_put(), this is safe.
1409          * As long as we still need to submit our private bio,
1410          * we hold a completion ref, and the request cannot disappear.
1411          * If however this request did not even have a private bio to submit
1412          * (e.g. remote read), req may already be invalid now.
1413          * That's why we cannot check on req->private_bio. */
1414         if (submit_private_bio)
1415                 drbd_submit_req_private_bio(req);
1416         if (m.bio)
1417                 complete_master_bio(device, &m);
1418 }
1419
1420 void __drbd_make_request(struct drbd_device *device, struct bio *bio, unsigned long start_jif)
1421 {
1422         struct drbd_request *req = drbd_request_prepare(device, bio, start_jif);
1423         if (IS_ERR_OR_NULL(req))
1424                 return;
1425         drbd_send_and_submit(device, req);
1426 }
1427
1428 static void submit_fast_path(struct drbd_device *device, struct list_head *incoming)
1429 {
1430         struct blk_plug plug;
1431         struct drbd_request *req, *tmp;
1432
1433         blk_start_plug(&plug);
1434         list_for_each_entry_safe(req, tmp, incoming, tl_requests) {
1435                 const int rw = bio_data_dir(req->master_bio);
1436
1437                 if (rw == WRITE /* rw != WRITE should not even end up here! */
1438                 && req->private_bio && req->i.size
1439                 && !test_bit(AL_SUSPENDED, &device->flags)) {
1440                         if (!drbd_al_begin_io_fastpath(device, &req->i))
1441                                 continue;
1442
1443                         req->rq_state |= RQ_IN_ACT_LOG;
1444                         req->in_actlog_jif = jiffies;
1445                         atomic_dec(&device->ap_actlog_cnt);
1446                 }
1447
1448                 list_del_init(&req->tl_requests);
1449                 drbd_send_and_submit(device, req);
1450         }
1451         blk_finish_plug(&plug);
1452 }
1453
1454 static bool prepare_al_transaction_nonblock(struct drbd_device *device,
1455                                             struct list_head *incoming,
1456                                             struct list_head *pending,
1457                                             struct list_head *later)
1458 {
1459         struct drbd_request *req;
1460         int wake = 0;
1461         int err;
1462
1463         spin_lock_irq(&device->al_lock);
1464         while ((req = list_first_entry_or_null(incoming, struct drbd_request, tl_requests))) {
1465                 err = drbd_al_begin_io_nonblock(device, &req->i);
1466                 if (err == -ENOBUFS)
1467                         break;
1468                 if (err == -EBUSY)
1469                         wake = 1;
1470                 if (err)
1471                         list_move_tail(&req->tl_requests, later);
1472                 else
1473                         list_move_tail(&req->tl_requests, pending);
1474         }
1475         spin_unlock_irq(&device->al_lock);
1476         if (wake)
1477                 wake_up(&device->al_wait);
1478         return !list_empty(pending);
1479 }
1480
1481 static void send_and_submit_pending(struct drbd_device *device, struct list_head *pending)
1482 {
1483         struct blk_plug plug;
1484         struct drbd_request *req;
1485
1486         blk_start_plug(&plug);
1487         while ((req = list_first_entry_or_null(pending, struct drbd_request, tl_requests))) {
1488                 req->rq_state |= RQ_IN_ACT_LOG;
1489                 req->in_actlog_jif = jiffies;
1490                 atomic_dec(&device->ap_actlog_cnt);
1491                 list_del_init(&req->tl_requests);
1492                 drbd_send_and_submit(device, req);
1493         }
1494         blk_finish_plug(&plug);
1495 }
1496
1497 void do_submit(struct work_struct *ws)
1498 {
1499         struct drbd_device *device = container_of(ws, struct drbd_device, submit.worker);
1500         LIST_HEAD(incoming);    /* from drbd_make_request() */
1501         LIST_HEAD(pending);     /* to be submitted after next AL-transaction commit */
1502         LIST_HEAD(busy);        /* blocked by resync requests */
1503
1504         /* grab new incoming requests */
1505         spin_lock_irq(&device->resource->req_lock);
1506         list_splice_tail_init(&device->submit.writes, &incoming);
1507         spin_unlock_irq(&device->resource->req_lock);
1508
1509         for (;;) {
1510                 DEFINE_WAIT(wait);
1511
1512                 /* move used-to-be-busy back to front of incoming */
1513                 list_splice_init(&busy, &incoming);
1514                 submit_fast_path(device, &incoming);
1515                 if (list_empty(&incoming))
1516                         break;
1517
1518                 for (;;) {
1519                         prepare_to_wait(&device->al_wait, &wait, TASK_UNINTERRUPTIBLE);
1520
1521                         list_splice_init(&busy, &incoming);
1522                         prepare_al_transaction_nonblock(device, &incoming, &pending, &busy);
1523                         if (!list_empty(&pending))
1524                                 break;
1525
1526                         schedule();
1527
1528                         /* If all currently "hot" activity log extents are kept busy by
1529                          * incoming requests, we still must not totally starve new
1530                          * requests to "cold" extents.
1531                          * Something left on &incoming means there had not been
1532                          * enough update slots available, and the activity log
1533                          * has been marked as "starving".
1534                          *
1535                          * Try again now, without looking for new requests,
1536                          * effectively blocking all new requests until we made
1537                          * at least _some_ progress with what we currently have.
1538                          */
1539                         if (!list_empty(&incoming))
1540                                 continue;
1541
1542                         /* Nothing moved to pending, but nothing left
1543                          * on incoming: all moved to busy!
1544                          * Grab new and iterate. */
1545                         spin_lock_irq(&device->resource->req_lock);
1546                         list_splice_tail_init(&device->submit.writes, &incoming);
1547                         spin_unlock_irq(&device->resource->req_lock);
1548                 }
1549                 finish_wait(&device->al_wait, &wait);
1550
1551                 /* If the transaction was full, before all incoming requests
1552                  * had been processed, skip ahead to commit, and iterate
1553                  * without splicing in more incoming requests from upper layers.
1554                  *
1555                  * Else, if all incoming have been processed,
1556                  * they have become either "pending" (to be submitted after
1557                  * next transaction commit) or "busy" (blocked by resync).
1558                  *
1559                  * Maybe more was queued, while we prepared the transaction?
1560                  * Try to stuff those into this transaction as well.
1561                  * Be strictly non-blocking here,
1562                  * we already have something to commit.
1563                  *
1564                  * Commit if we don't make any more progres.
1565                  */
1566
1567                 while (list_empty(&incoming)) {
1568                         LIST_HEAD(more_pending);
1569                         LIST_HEAD(more_incoming);
1570                         bool made_progress;
1571
1572                         /* It is ok to look outside the lock,
1573                          * it's only an optimization anyways */
1574                         if (list_empty(&device->submit.writes))
1575                                 break;
1576
1577                         spin_lock_irq(&device->resource->req_lock);
1578                         list_splice_tail_init(&device->submit.writes, &more_incoming);
1579                         spin_unlock_irq(&device->resource->req_lock);
1580
1581                         if (list_empty(&more_incoming))
1582                                 break;
1583
1584                         made_progress = prepare_al_transaction_nonblock(device, &more_incoming, &more_pending, &busy);
1585
1586                         list_splice_tail_init(&more_pending, &pending);
1587                         list_splice_tail_init(&more_incoming, &incoming);
1588                         if (!made_progress)
1589                                 break;
1590                 }
1591
1592                 drbd_al_begin_io_commit(device);
1593                 send_and_submit_pending(device, &pending);
1594         }
1595 }
1596
1597 blk_qc_t drbd_submit_bio(struct bio *bio)
1598 {
1599         struct drbd_device *device = bio->bi_disk->private_data;
1600         unsigned long start_jif;
1601
1602         blk_queue_split(&bio);
1603
1604         start_jif = jiffies;
1605
1606         /*
1607          * what we "blindly" assume:
1608          */
1609         D_ASSERT(device, IS_ALIGNED(bio->bi_iter.bi_size, 512));
1610
1611         inc_ap_bio(device);
1612         __drbd_make_request(device, bio, start_jif);
1613         return BLK_QC_T_NONE;
1614 }
1615
1616 static bool net_timeout_reached(struct drbd_request *net_req,
1617                 struct drbd_connection *connection,
1618                 unsigned long now, unsigned long ent,
1619                 unsigned int ko_count, unsigned int timeout)
1620 {
1621         struct drbd_device *device = net_req->device;
1622
1623         if (!time_after(now, net_req->pre_send_jif + ent))
1624                 return false;
1625
1626         if (time_in_range(now, connection->last_reconnect_jif, connection->last_reconnect_jif + ent))
1627                 return false;
1628
1629         if (net_req->rq_state & RQ_NET_PENDING) {
1630                 drbd_warn(device, "Remote failed to finish a request within %ums > ko-count (%u) * timeout (%u * 0.1s)\n",
1631                         jiffies_to_msecs(now - net_req->pre_send_jif), ko_count, timeout);
1632                 return true;
1633         }
1634
1635         /* We received an ACK already (or are using protocol A),
1636          * but are waiting for the epoch closing barrier ack.
1637          * Check if we sent the barrier already.  We should not blame the peer
1638          * for being unresponsive, if we did not even ask it yet. */
1639         if (net_req->epoch == connection->send.current_epoch_nr) {
1640                 drbd_warn(device,
1641                         "We did not send a P_BARRIER for %ums > ko-count (%u) * timeout (%u * 0.1s); drbd kernel thread blocked?\n",
1642                         jiffies_to_msecs(now - net_req->pre_send_jif), ko_count, timeout);
1643                 return false;
1644         }
1645
1646         /* Worst case: we may have been blocked for whatever reason, then
1647          * suddenly are able to send a lot of requests (and epoch separating
1648          * barriers) in quick succession.
1649          * The timestamp of the net_req may be much too old and not correspond
1650          * to the sending time of the relevant unack'ed barrier packet, so
1651          * would trigger a spurious timeout.  The latest barrier packet may
1652          * have a too recent timestamp to trigger the timeout, potentially miss
1653          * a timeout.  Right now we don't have a place to conveniently store
1654          * these timestamps.
1655          * But in this particular situation, the application requests are still
1656          * completed to upper layers, DRBD should still "feel" responsive.
1657          * No need yet to kill this connection, it may still recover.
1658          * If not, eventually we will have queued enough into the network for
1659          * us to block. From that point of view, the timestamp of the last sent
1660          * barrier packet is relevant enough.
1661          */
1662         if (time_after(now, connection->send.last_sent_barrier_jif + ent)) {
1663                 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",
1664                         connection->send.last_sent_barrier_jif, now,
1665                         jiffies_to_msecs(now - connection->send.last_sent_barrier_jif), ko_count, timeout);
1666                 return true;
1667         }
1668         return false;
1669 }
1670
1671 /* A request is considered timed out, if
1672  * - we have some effective timeout from the configuration,
1673  *   with some state restrictions applied,
1674  * - the oldest request is waiting for a response from the network
1675  *   resp. the local disk,
1676  * - the oldest request is in fact older than the effective timeout,
1677  * - the connection was established (resp. disk was attached)
1678  *   for longer than the timeout already.
1679  * Note that for 32bit jiffies and very stable connections/disks,
1680  * we may have a wrap around, which is catched by
1681  *   !time_in_range(now, last_..._jif, last_..._jif + timeout).
1682  *
1683  * Side effect: once per 32bit wrap-around interval, which means every
1684  * ~198 days with 250 HZ, we have a window where the timeout would need
1685  * to expire twice (worst case) to become effective. Good enough.
1686  */
1687
1688 void request_timer_fn(struct timer_list *t)
1689 {
1690         struct drbd_device *device = from_timer(device, t, request_timer);
1691         struct drbd_connection *connection = first_peer_device(device)->connection;
1692         struct drbd_request *req_read, *req_write, *req_peer; /* oldest request */
1693         struct net_conf *nc;
1694         unsigned long oldest_submit_jif;
1695         unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */
1696         unsigned long now;
1697         unsigned int ko_count = 0, timeout = 0;
1698
1699         rcu_read_lock();
1700         nc = rcu_dereference(connection->net_conf);
1701         if (nc && device->state.conn >= C_WF_REPORT_PARAMS) {
1702                 ko_count = nc->ko_count;
1703                 timeout = nc->timeout;
1704         }
1705
1706         if (get_ldev(device)) { /* implicit state.disk >= D_INCONSISTENT */
1707                 dt = rcu_dereference(device->ldev->disk_conf)->disk_timeout * HZ / 10;
1708                 put_ldev(device);
1709         }
1710         rcu_read_unlock();
1711
1712
1713         ent = timeout * HZ/10 * ko_count;
1714         et = min_not_zero(dt, ent);
1715
1716         if (!et)
1717                 return; /* Recurring timer stopped */
1718
1719         now = jiffies;
1720         nt = now + et;
1721
1722         spin_lock_irq(&device->resource->req_lock);
1723         req_read = list_first_entry_or_null(&device->pending_completion[0], struct drbd_request, req_pending_local);
1724         req_write = list_first_entry_or_null(&device->pending_completion[1], struct drbd_request, req_pending_local);
1725
1726         /* maybe the oldest request waiting for the peer is in fact still
1727          * blocking in tcp sendmsg.  That's ok, though, that's handled via the
1728          * socket send timeout, requesting a ping, and bumping ko-count in
1729          * we_should_drop_the_connection().
1730          */
1731
1732         /* check the oldest request we did successfully sent,
1733          * but which is still waiting for an ACK. */
1734         req_peer = connection->req_ack_pending;
1735
1736         /* if we don't have such request (e.g. protocoll A)
1737          * check the oldest requests which is still waiting on its epoch
1738          * closing barrier ack. */
1739         if (!req_peer)
1740                 req_peer = connection->req_not_net_done;
1741
1742         /* evaluate the oldest peer request only in one timer! */
1743         if (req_peer && req_peer->device != device)
1744                 req_peer = NULL;
1745
1746         /* do we have something to evaluate? */
1747         if (req_peer == NULL && req_write == NULL && req_read == NULL)
1748                 goto out;
1749
1750         oldest_submit_jif =
1751                 (req_write && req_read)
1752                 ? ( time_before(req_write->pre_submit_jif, req_read->pre_submit_jif)
1753                   ? req_write->pre_submit_jif : req_read->pre_submit_jif )
1754                 : req_write ? req_write->pre_submit_jif
1755                 : req_read ? req_read->pre_submit_jif : now;
1756
1757         if (ent && req_peer && net_timeout_reached(req_peer, connection, now, ent, ko_count, timeout))
1758                 _conn_request_state(connection, NS(conn, C_TIMEOUT), CS_VERBOSE | CS_HARD);
1759
1760         if (dt && oldest_submit_jif != now &&
1761                  time_after(now, oldest_submit_jif + dt) &&
1762                 !time_in_range(now, device->last_reattach_jif, device->last_reattach_jif + dt)) {
1763                 drbd_warn(device, "Local backing device failed to meet the disk-timeout\n");
1764                 __drbd_chk_io_error(device, DRBD_FORCE_DETACH);
1765         }
1766
1767         /* Reschedule timer for the nearest not already expired timeout.
1768          * Fallback to now + min(effective network timeout, disk timeout). */
1769         ent = (ent && req_peer && time_before(now, req_peer->pre_send_jif + ent))
1770                 ? req_peer->pre_send_jif + ent : now + et;
1771         dt = (dt && oldest_submit_jif != now && time_before(now, oldest_submit_jif + dt))
1772                 ? oldest_submit_jif + dt : now + et;
1773         nt = time_before(ent, dt) ? ent : dt;
1774 out:
1775         spin_unlock_irq(&device->resource->req_lock);
1776         mod_timer(&device->request_timer, nt);
1777 }