drivers/block/drbd/drbd_actlog.c

   1 /*
   2    drbd_actlog.c
   3
   4    This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
   5
   6    Copyright (C) 2003-2008, LINBIT Information Technologies GmbH.
   7    Copyright (C) 2003-2008, Philipp Reisner <philipp.reisner@linbit.com>.
   8    Copyright (C) 2003-2008, 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/slab.h>
  27 #include <linux/crc32c.h>
  28 #include <linux/drbd.h>
  29 #include <linux/drbd_limits.h>
  30 #include <linux/dynamic_debug.h>
  31 #include "drbd_int.h"
  32
  33
  34 enum al_transaction_types {
  35         AL_TR_UPDATE = 0,
  36         AL_TR_INITIALIZED = 0xffff
  37 };
  38 /* all fields on disc in big endian */
  39 struct __packed al_transaction_on_disk {
  40         /* don't we all like magic */
  41         __be32  magic;
  42
  43         /* to identify the most recent transaction block
  44          * in the on disk ring buffer */
  45         __be32  tr_number;
  46
  47         /* checksum on the full 4k block, with this field set to 0. */
  48         __be32  crc32c;
  49
  50         /* type of transaction, special transaction types like:
  51          * purge-all, set-all-idle, set-all-active, ... to-be-defined
  52          * see also enum al_transaction_types */
  53         __be16  transaction_type;
  54
  55         /* we currently allow only a few thousand extents,
  56          * so 16bit will be enough for the slot number. */
  57
  58         /* how many updates in this transaction */
  59         __be16  n_updates;
  60
  61         /* maximum slot number, "al-extents" in drbd.conf speak.
  62          * Having this in each transaction should make reconfiguration
  63          * of that parameter easier. */
  64         __be16  context_size;
  65
  66         /* slot number the context starts with */
  67         __be16  context_start_slot_nr;
  68
  69         /* Some reserved bytes.  Expected usage is a 64bit counter of
  70          * sectors-written since device creation, and other data generation tag
  71          * supporting usage */
  72         __be32  __reserved[4];
  73
  74         /* --- 36 byte used --- */
  75
  76         /* Reserve space for up to AL_UPDATES_PER_TRANSACTION changes
  77          * in one transaction, then use the remaining byte in the 4k block for
  78          * context information.  "Flexible" number of updates per transaction
  79          * does not help, as we have to account for the case when all update
  80          * slots are used anyways, so it would only complicate code without
  81          * additional benefit.
  82          */
  83         __be16  update_slot_nr[AL_UPDATES_PER_TRANSACTION];
  84
  85         /* but the extent number is 32bit, which at an extent size of 4 MiB
  86          * allows to cover device sizes of up to 2**54 Byte (16 PiB) */
  87         __be32  update_extent_nr[AL_UPDATES_PER_TRANSACTION];
  88
  89         /* --- 420 bytes used (36 + 64*6) --- */
  90
  91         /* 4096 - 420 = 3676 = 919 * 4 */
  92         __be32  context[AL_CONTEXT_PER_TRANSACTION];
  93 };
  94
  95 void *drbd_md_get_buffer(struct drbd_device *device, const char *intent)
  96 {
  97         int r;
  98
  99         wait_event(device->misc_wait,
 100                    (r = atomic_cmpxchg(&device->md_io.in_use, 0, 1)) == 0 ||
 101                    device->state.disk <= D_FAILED);
 102
 103         if (r)
 104                 return NULL;
 105
 106         device->md_io.current_use = intent;
 107         device->md_io.start_jif = jiffies;
 108         device->md_io.submit_jif = device->md_io.start_jif - 1;
 109         return page_address(device->md_io.page);
 110 }
 111
 112 void drbd_md_put_buffer(struct drbd_device *device)
 113 {
 114         if (atomic_dec_and_test(&device->md_io.in_use))
 115                 wake_up(&device->misc_wait);
 116 }
 117
 118 void wait_until_done_or_force_detached(struct drbd_device *device, struct drbd_backing_dev *bdev,
 119                                      unsigned int *done)
 120 {
 121         long dt;
 122
 123         rcu_read_lock();
 124         dt = rcu_dereference(bdev->disk_conf)->disk_timeout;
 125         rcu_read_unlock();
 126         dt = dt * HZ / 10;
 127         if (dt == 0)
 128                 dt = MAX_SCHEDULE_TIMEOUT;
 129
 130         dt = wait_event_timeout(device->misc_wait,
 131                         *done || test_bit(FORCE_DETACH, &device->flags), dt);
 132         if (dt == 0) {
 133                 drbd_err(device, "meta-data IO operation timed out\n");
 134                 drbd_chk_io_error(device, 1, DRBD_FORCE_DETACH);
 135         }
 136 }
 137
 138 static int _drbd_md_sync_page_io(struct drbd_device *device,
 139                                  struct drbd_backing_dev *bdev,
 140                                  sector_t sector, int op)
 141 {
 142         struct bio *bio;
 143         /* we do all our meta data IO in aligned 4k blocks. */
 144         const int size = 4096;
 145         int err, op_flags = 0;
 146
 147         device->md_io.done = 0;
 148         device->md_io.error = -ENODEV;
 149
 150         if ((op == REQ_OP_WRITE) && !test_bit(MD_NO_FUA, &device->flags))
 151                 op_flags |= REQ_FUA | REQ_PREFLUSH;
 152         op_flags |= REQ_SYNC | REQ_NOIDLE;
 153
 154         bio = bio_alloc_drbd(GFP_NOIO);
 155         bio->bi_bdev = bdev->md_bdev;
 156         bio->bi_iter.bi_sector = sector;
 157         err = -EIO;
 158         if (bio_add_page(bio, device->md_io.page, size, 0) != size)
 159                 goto out;
 160         bio->bi_private = device;
 161         bio->bi_end_io = drbd_md_endio;
 162         bio_set_op_attrs(bio, op, op_flags);
 163
 164         if (op != REQ_OP_WRITE && device->state.disk == D_DISKLESS && device->ldev == NULL)
 165                 /* special case, drbd_md_read() during drbd_adm_attach(): no get_ldev */
 166                 ;
 167         else if (!get_ldev_if_state(device, D_ATTACHING)) {
 168                 /* Corresponding put_ldev in drbd_md_endio() */
 169                 drbd_err(device, "ASSERT FAILED: get_ldev_if_state() == 1 in _drbd_md_sync_page_io()\n");
 170                 err = -ENODEV;
 171                 goto out;
 172         }
 173
 174         bio_get(bio); /* one bio_put() is in the completion handler */
 175         atomic_inc(&device->md_io.in_use); /* drbd_md_put_buffer() is in the completion handler */
 176         device->md_io.submit_jif = jiffies;
 177         if (drbd_insert_fault(device, (op == REQ_OP_WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))
 178                 bio_io_error(bio);
 179         else
 180                 submit_bio(bio);
 181         wait_until_done_or_force_detached(device, bdev, &device->md_io.done);
 182         if (!bio->bi_error)
 183                 err = device->md_io.error;
 184
 185  out:
 186         bio_put(bio);
 187         return err;
 188 }
 189
 190 int drbd_md_sync_page_io(struct drbd_device *device, struct drbd_backing_dev *bdev,
 191                          sector_t sector, int op)
 192 {
 193         int err;
 194         D_ASSERT(device, atomic_read(&device->md_io.in_use) == 1);
 195
 196         BUG_ON(!bdev->md_bdev);
 197
 198         dynamic_drbd_dbg(device, "meta_data io: %s [%d]:%s(,%llus,%s) %pS\n",
 199              current->comm, current->pid, __func__,
 200              (unsigned long long)sector, (op == REQ_OP_WRITE) ? "WRITE" : "READ",
 201              (void*)_RET_IP_ );
 202
 203         if (sector < drbd_md_first_sector(bdev) ||
 204             sector + 7 > drbd_md_last_sector(bdev))
 205                 drbd_alert(device, "%s [%d]:%s(,%llus,%s) out of range md access!\n",
 206                      current->comm, current->pid, __func__,
 207                      (unsigned long long)sector,
 208                      (op == REQ_OP_WRITE) ? "WRITE" : "READ");
 209
 210         err = _drbd_md_sync_page_io(device, bdev, sector, op);
 211         if (err) {
 212                 drbd_err(device, "drbd_md_sync_page_io(,%llus,%s) failed with error %d\n",
 213                     (unsigned long long)sector,
 214                     (op == REQ_OP_WRITE) ? "WRITE" : "READ", err);
 215         }
 216         return err;
 217 }
 218
 219 static struct bm_extent *find_active_resync_extent(struct drbd_device *device, unsigned int enr)
 220 {
 221         struct lc_element *tmp;
 222         tmp = lc_find(device->resync, enr/AL_EXT_PER_BM_SECT);
 223         if (unlikely(tmp != NULL)) {
 224                 struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
 225                 if (test_bit(BME_NO_WRITES, &bm_ext->flags))
 226                         return bm_ext;
 227         }
 228         return NULL;
 229 }
 230
 231 static struct lc_element *_al_get(struct drbd_device *device, unsigned int enr, bool nonblock)
 232 {
 233         struct lc_element *al_ext;
 234         struct bm_extent *bm_ext;
 235         int wake;
 236
 237         spin_lock_irq(&device->al_lock);
 238         bm_ext = find_active_resync_extent(device, enr);
 239         if (bm_ext) {
 240                 wake = !test_and_set_bit(BME_PRIORITY, &bm_ext->flags);
 241                 spin_unlock_irq(&device->al_lock);
 242                 if (wake)
 243                         wake_up(&device->al_wait);
 244                 return NULL;
 245         }
 246         if (nonblock)
 247                 al_ext = lc_try_get(device->act_log, enr);
 248         else
 249                 al_ext = lc_get(device->act_log, enr);
 250         spin_unlock_irq(&device->al_lock);
 251         return al_ext;
 252 }
 253
 254 bool drbd_al_begin_io_fastpath(struct drbd_device *device, struct drbd_interval *i)
 255 {
 256         /* for bios crossing activity log extent boundaries,
 257          * we may need to activate two extents in one go */
 258         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 259         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 260
 261         D_ASSERT(device, first <= last);
 262         D_ASSERT(device, atomic_read(&device->local_cnt) > 0);
 263
 264         /* FIXME figure out a fast path for bios crossing AL extent boundaries */
 265         if (first != last)
 266                 return false;
 267
 268         return _al_get(device, first, true);
 269 }
 270
 271 bool drbd_al_begin_io_prepare(struct drbd_device *device, struct drbd_interval *i)
 272 {
 273         /* for bios crossing activity log extent boundaries,
 274          * we may need to activate two extents in one go */
 275         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 276         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 277         unsigned enr;
 278         bool need_transaction = false;
 279
 280         D_ASSERT(device, first <= last);
 281         D_ASSERT(device, atomic_read(&device->local_cnt) > 0);
 282
 283         for (enr = first; enr <= last; enr++) {
 284                 struct lc_element *al_ext;
 285                 wait_event(device->al_wait,
 286                                 (al_ext = _al_get(device, enr, false)) != NULL);
 287                 if (al_ext->lc_number != enr)
 288                         need_transaction = true;
 289         }
 290         return need_transaction;
 291 }
 292
 293 #if (PAGE_SHIFT + 3) < (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT)
 294 /* Currently BM_BLOCK_SHIFT, BM_EXT_SHIFT and AL_EXTENT_SHIFT
 295  * are still coupled, or assume too much about their relation.
 296  * Code below will not work if this is violated.
 297  * Will be cleaned up with some followup patch.
 298  */
 299 # error FIXME
 300 #endif
 301
 302 static unsigned int al_extent_to_bm_page(unsigned int al_enr)
 303 {
 304         return al_enr >>
 305                 /* bit to page */
 306                 ((PAGE_SHIFT + 3) -
 307                 /* al extent number to bit */
 308                  (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT));
 309 }
 310
 311 static sector_t al_tr_number_to_on_disk_sector(struct drbd_device *device)
 312 {
 313         const unsigned int stripes = device->ldev->md.al_stripes;
 314         const unsigned int stripe_size_4kB = device->ldev->md.al_stripe_size_4k;
 315
 316         /* transaction number, modulo on-disk ring buffer wrap around */
 317         unsigned int t = device->al_tr_number % (device->ldev->md.al_size_4k);
 318
 319         /* ... to aligned 4k on disk block */
 320         t = ((t % stripes) * stripe_size_4kB) + t/stripes;
 321
 322         /* ... to 512 byte sector in activity log */
 323         t *= 8;
 324
 325         /* ... plus offset to the on disk position */
 326         return device->ldev->md.md_offset + device->ldev->md.al_offset + t;
 327 }
 328
 329 static int __al_write_transaction(struct drbd_device *device, struct al_transaction_on_disk *buffer)
 330 {
 331         struct lc_element *e;
 332         sector_t sector;
 333         int i, mx;
 334         unsigned extent_nr;
 335         unsigned crc = 0;
 336         int err = 0;
 337
 338         memset(buffer, 0, sizeof(*buffer));
 339         buffer->magic = cpu_to_be32(DRBD_AL_MAGIC);
 340         buffer->tr_number = cpu_to_be32(device->al_tr_number);
 341
 342         i = 0;
 343
 344         drbd_bm_reset_al_hints(device);
 345
 346         /* Even though no one can start to change this list
 347          * once we set the LC_LOCKED -- from drbd_al_begin_io(),
 348          * lc_try_lock_for_transaction() --, someone may still
 349          * be in the process of changing it. */
 350         spin_lock_irq(&device->al_lock);
 351         list_for_each_entry(e, &device->act_log->to_be_changed, list) {
 352                 if (i == AL_UPDATES_PER_TRANSACTION) {
 353                         i++;
 354                         break;
 355                 }
 356                 buffer->update_slot_nr[i] = cpu_to_be16(e->lc_index);
 357                 buffer->update_extent_nr[i] = cpu_to_be32(e->lc_new_number);
 358                 if (e->lc_number != LC_FREE)
 359                         drbd_bm_mark_for_writeout(device,
 360                                         al_extent_to_bm_page(e->lc_number));
 361                 i++;
 362         }
 363         spin_unlock_irq(&device->al_lock);
 364         BUG_ON(i > AL_UPDATES_PER_TRANSACTION);
 365
 366         buffer->n_updates = cpu_to_be16(i);
 367         for ( ; i < AL_UPDATES_PER_TRANSACTION; i++) {
 368                 buffer->update_slot_nr[i] = cpu_to_be16(-1);
 369                 buffer->update_extent_nr[i] = cpu_to_be32(LC_FREE);
 370         }
 371
 372         buffer->context_size = cpu_to_be16(device->act_log->nr_elements);
 373         buffer->context_start_slot_nr = cpu_to_be16(device->al_tr_cycle);
 374
 375         mx = min_t(int, AL_CONTEXT_PER_TRANSACTION,
 376                    device->act_log->nr_elements - device->al_tr_cycle);
 377         for (i = 0; i < mx; i++) {
 378                 unsigned idx = device->al_tr_cycle + i;
 379                 extent_nr = lc_element_by_index(device->act_log, idx)->lc_number;
 380                 buffer->context[i] = cpu_to_be32(extent_nr);
 381         }
 382         for (; i < AL_CONTEXT_PER_TRANSACTION; i++)
 383                 buffer->context[i] = cpu_to_be32(LC_FREE);
 384
 385         device->al_tr_cycle += AL_CONTEXT_PER_TRANSACTION;
 386         if (device->al_tr_cycle >= device->act_log->nr_elements)
 387                 device->al_tr_cycle = 0;
 388
 389         sector = al_tr_number_to_on_disk_sector(device);
 390
 391         crc = crc32c(0, buffer, 4096);
 392         buffer->crc32c = cpu_to_be32(crc);
 393
 394         if (drbd_bm_write_hinted(device))
 395                 err = -EIO;
 396         else {
 397                 bool write_al_updates;
 398                 rcu_read_lock();
 399                 write_al_updates = rcu_dereference(device->ldev->disk_conf)->al_updates;
 400                 rcu_read_unlock();
 401                 if (write_al_updates) {
 402                         if (drbd_md_sync_page_io(device, device->ldev, sector, WRITE)) {
 403                                 err = -EIO;
 404                                 drbd_chk_io_error(device, 1, DRBD_META_IO_ERROR);
 405                         } else {
 406                                 device->al_tr_number++;
 407                                 device->al_writ_cnt++;
 408                         }
 409                 }
 410         }
 411
 412         return err;
 413 }
 414
 415 static int al_write_transaction(struct drbd_device *device)
 416 {
 417         struct al_transaction_on_disk *buffer;
 418         int err;
 419
 420         if (!get_ldev(device)) {
 421                 drbd_err(device, "disk is %s, cannot start al transaction\n",
 422                         drbd_disk_str(device->state.disk));
 423                 return -EIO;
 424         }
 425
 426         /* The bitmap write may have failed, causing a state change. */
 427         if (device->state.disk < D_INCONSISTENT) {
 428                 drbd_err(device,
 429                         "disk is %s, cannot write al transaction\n",
 430                         drbd_disk_str(device->state.disk));
 431                 put_ldev(device);
 432                 return -EIO;
 433         }
 434
 435         /* protects md_io_buffer, al_tr_cycle, ... */
 436         buffer = drbd_md_get_buffer(device, __func__);
 437         if (!buffer) {
 438                 drbd_err(device, "disk failed while waiting for md_io buffer\n");
 439                 put_ldev(device);
 440                 return -ENODEV;
 441         }
 442
 443         err = __al_write_transaction(device, buffer);
 444
 445         drbd_md_put_buffer(device);
 446         put_ldev(device);
 447
 448         return err;
 449 }
 450
 451
 452 void drbd_al_begin_io_commit(struct drbd_device *device)
 453 {
 454         bool locked = false;
 455
 456         /* Serialize multiple transactions.
 457          * This uses test_and_set_bit, memory barrier is implicit.
 458          */
 459         wait_event(device->al_wait,
 460                         device->act_log->pending_changes == 0 ||
 461                         (locked = lc_try_lock_for_transaction(device->act_log)));
 462
 463         if (locked) {
 464                 /* Double check: it may have been committed by someone else,
 465                  * while we have been waiting for the lock. */
 466                 if (device->act_log->pending_changes) {
 467                         bool write_al_updates;
 468
 469                         rcu_read_lock();
 470                         write_al_updates = rcu_dereference(device->ldev->disk_conf)->al_updates;
 471                         rcu_read_unlock();
 472
 473                         if (write_al_updates)
 474                                 al_write_transaction(device);
 475                         spin_lock_irq(&device->al_lock);
 476                         /* FIXME
 477                         if (err)
 478                                 we need an "lc_cancel" here;
 479                         */
 480                         lc_committed(device->act_log);
 481                         spin_unlock_irq(&device->al_lock);
 482                 }
 483                 lc_unlock(device->act_log);
 484                 wake_up(&device->al_wait);
 485         }
 486 }
 487
 488 /*
 489  * @delegate:   delegate activity log I/O to the worker thread
 490  */
 491 void drbd_al_begin_io(struct drbd_device *device, struct drbd_interval *i)
 492 {
 493         if (drbd_al_begin_io_prepare(device, i))
 494                 drbd_al_begin_io_commit(device);
 495 }
 496
 497 int drbd_al_begin_io_nonblock(struct drbd_device *device, struct drbd_interval *i)
 498 {
 499         struct lru_cache *al = device->act_log;
 500         /* for bios crossing activity log extent boundaries,
 501          * we may need to activate two extents in one go */
 502         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 503         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 504         unsigned nr_al_extents;
 505         unsigned available_update_slots;
 506         unsigned enr;
 507
 508         D_ASSERT(device, first <= last);
 509
 510         nr_al_extents = 1 + last - first; /* worst case: all touched extends are cold. */
 511         available_update_slots = min(al->nr_elements - al->used,
 512                                 al->max_pending_changes - al->pending_changes);
 513
 514         /* We want all necessary updates for a given request within the same transaction
 515          * We could first check how many updates are *actually* needed,
 516          * and use that instead of the worst-case nr_al_extents */
 517         if (available_update_slots < nr_al_extents) {
 518                 /* Too many activity log extents are currently "hot".
 519                  *
 520                  * If we have accumulated pending changes already,
 521                  * we made progress.
 522                  *
 523                  * If we cannot get even a single pending change through,
 524                  * stop the fast path until we made some progress,
 525                  * or requests to "cold" extents could be starved. */
 526                 if (!al->pending_changes)
 527                         __set_bit(__LC_STARVING, &device->act_log->flags);
 528                 return -ENOBUFS;
 529         }
 530
 531         /* Is resync active in this area? */
 532         for (enr = first; enr <= last; enr++) {
 533                 struct lc_element *tmp;
 534                 tmp = lc_find(device->resync, enr/AL_EXT_PER_BM_SECT);
 535                 if (unlikely(tmp != NULL)) {
 536                         struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
 537                         if (test_bit(BME_NO_WRITES, &bm_ext->flags)) {
 538                                 if (!test_and_set_bit(BME_PRIORITY, &bm_ext->flags))
 539                                         return -EBUSY;
 540                                 return -EWOULDBLOCK;
 541                         }
 542                 }
 543         }
 544
 545         /* Checkout the refcounts.
 546          * Given that we checked for available elements and update slots above,
 547          * this has to be successful. */
 548         for (enr = first; enr <= last; enr++) {
 549                 struct lc_element *al_ext;
 550                 al_ext = lc_get_cumulative(device->act_log, enr);
 551                 if (!al_ext)
 552                         drbd_info(device, "LOGIC BUG for enr=%u\n", enr);
 553         }
 554         return 0;
 555 }
 556
 557 void drbd_al_complete_io(struct drbd_device *device, struct drbd_interval *i)
 558 {
 559         /* for bios crossing activity log extent boundaries,
 560          * we may need to activate two extents in one go */
 561         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 562         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 563         unsigned enr;
 564         struct lc_element *extent;
 565         unsigned long flags;
 566
 567         D_ASSERT(device, first <= last);
 568         spin_lock_irqsave(&device->al_lock, flags);
 569
 570         for (enr = first; enr <= last; enr++) {
 571                 extent = lc_find(device->act_log, enr);
 572                 if (!extent) {
 573                         drbd_err(device, "al_complete_io() called on inactive extent %u\n", enr);
 574                         continue;
 575                 }
 576                 lc_put(device->act_log, extent);
 577         }
 578         spin_unlock_irqrestore(&device->al_lock, flags);
 579         wake_up(&device->al_wait);
 580 }
 581
 582 static int _try_lc_del(struct drbd_device *device, struct lc_element *al_ext)
 583 {
 584         int rv;
 585
 586         spin_lock_irq(&device->al_lock);
 587         rv = (al_ext->refcnt == 0);
 588         if (likely(rv))
 589                 lc_del(device->act_log, al_ext);
 590         spin_unlock_irq(&device->al_lock);
 591
 592         return rv;
 593 }
 594
 595 /**
 596  * drbd_al_shrink() - Removes all active extents form the activity log
 597  * @device:     DRBD device.
 598  *
 599  * Removes all active extents form the activity log, waiting until
 600  * the reference count of each entry dropped to 0 first, of course.
 601  *
 602  * You need to lock device->act_log with lc_try_lock() / lc_unlock()
 603  */
 604 void drbd_al_shrink(struct drbd_device *device)
 605 {
 606         struct lc_element *al_ext;
 607         int i;
 608
 609         D_ASSERT(device, test_bit(__LC_LOCKED, &device->act_log->flags));
 610
 611         for (i = 0; i < device->act_log->nr_elements; i++) {
 612                 al_ext = lc_element_by_index(device->act_log, i);
 613                 if (al_ext->lc_number == LC_FREE)
 614                         continue;
 615                 wait_event(device->al_wait, _try_lc_del(device, al_ext));
 616         }
 617
 618         wake_up(&device->al_wait);
 619 }
 620
 621 int drbd_al_initialize(struct drbd_device *device, void *buffer)
 622 {
 623         struct al_transaction_on_disk *al = buffer;
 624         struct drbd_md *md = &device->ldev->md;
 625         int al_size_4k = md->al_stripes * md->al_stripe_size_4k;
 626         int i;
 627
 628         __al_write_transaction(device, al);
 629         /* There may or may not have been a pending transaction. */
 630         spin_lock_irq(&device->al_lock);
 631         lc_committed(device->act_log);
 632         spin_unlock_irq(&device->al_lock);
 633
 634         /* The rest of the transactions will have an empty "updates" list, and
 635          * are written out only to provide the context, and to initialize the
 636          * on-disk ring buffer. */
 637         for (i = 1; i < al_size_4k; i++) {
 638                 int err = __al_write_transaction(device, al);
 639                 if (err)
 640                         return err;
 641         }
 642         return 0;
 643 }
 644
 645 static const char *drbd_change_sync_fname[] = {
 646         [RECORD_RS_FAILED] = "drbd_rs_failed_io",
 647         [SET_IN_SYNC] = "drbd_set_in_sync",
 648         [SET_OUT_OF_SYNC] = "drbd_set_out_of_sync"
 649 };
 650
 651 /* ATTENTION. The AL's extents are 4MB each, while the extents in the
 652  * resync LRU-cache are 16MB each.
 653  * The caller of this function has to hold an get_ldev() reference.
 654  *
 655  * Adjusts the caching members ->rs_left (success) or ->rs_failed (!success),
 656  * potentially pulling in (and recounting the corresponding bits)
 657  * this resync extent into the resync extent lru cache.
 658  *
 659  * Returns whether all bits have been cleared for this resync extent,
 660  * precisely: (rs_left <= rs_failed)
 661  *
 662  * TODO will be obsoleted once we have a caching lru of the on disk bitmap
 663  */
 664 static bool update_rs_extent(struct drbd_device *device,
 665                 unsigned int enr, int count,
 666                 enum update_sync_bits_mode mode)
 667 {
 668         struct lc_element *e;
 669
 670         D_ASSERT(device, atomic_read(&device->local_cnt));
 671
 672         /* When setting out-of-sync bits,
 673          * we don't need it cached (lc_find).
 674          * But if it is present in the cache,
 675          * we should update the cached bit count.
 676          * Otherwise, that extent should be in the resync extent lru cache
 677          * already -- or we want to pull it in if necessary -- (lc_get),
 678          * then update and check rs_left and rs_failed. */
 679         if (mode == SET_OUT_OF_SYNC)
 680                 e = lc_find(device->resync, enr);
 681         else
 682                 e = lc_get(device->resync, enr);
 683         if (e) {
 684                 struct bm_extent *ext = lc_entry(e, struct bm_extent, lce);
 685                 if (ext->lce.lc_number == enr) {
 686                         if (mode == SET_IN_SYNC)
 687                                 ext->rs_left -= count;
 688                         else if (mode == SET_OUT_OF_SYNC)
 689                                 ext->rs_left += count;
 690                         else
 691                                 ext->rs_failed += count;
 692                         if (ext->rs_left < ext->rs_failed) {
 693                                 drbd_warn(device, "BAD! enr=%u rs_left=%d "
 694                                     "rs_failed=%d count=%d cstate=%s\n",
 695                                      ext->lce.lc_number, ext->rs_left,
 696                                      ext->rs_failed, count,
 697                                      drbd_conn_str(device->state.conn));
 698
 699                                 /* We don't expect to be able to clear more bits
 700                                  * than have been set when we originally counted
 701                                  * the set bits to cache that value in ext->rs_left.
 702                                  * Whatever the reason (disconnect during resync,
 703                                  * delayed local completion of an application write),
 704                                  * try to fix it up by recounting here. */
 705                                 ext->rs_left = drbd_bm_e_weight(device, enr);
 706                         }
 707                 } else {
 708                         /* Normally this element should be in the cache,
 709                          * since drbd_rs_begin_io() pulled it already in.
 710                          *
 711                          * But maybe an application write finished, and we set
 712                          * something outside the resync lru_cache in sync.
 713                          */
 714                         int rs_left = drbd_bm_e_weight(device, enr);
 715                         if (ext->flags != 0) {
 716                                 drbd_warn(device, "changing resync lce: %d[%u;%02lx]"
 717                                      " -> %d[%u;00]\n",
 718                                      ext->lce.lc_number, ext->rs_left,
 719                                      ext->flags, enr, rs_left);
 720                                 ext->flags = 0;
 721                         }
 722                         if (ext->rs_failed) {
 723                                 drbd_warn(device, "Kicking resync_lru element enr=%u "
 724                                      "out with rs_failed=%d\n",
 725                                      ext->lce.lc_number, ext->rs_failed);
 726                         }
 727                         ext->rs_left = rs_left;
 728                         ext->rs_failed = (mode == RECORD_RS_FAILED) ? count : 0;
 729                         /* we don't keep a persistent log of the resync lru,
 730                          * we can commit any change right away. */
 731                         lc_committed(device->resync);
 732                 }
 733                 if (mode != SET_OUT_OF_SYNC)
 734                         lc_put(device->resync, &ext->lce);
 735                 /* no race, we are within the al_lock! */
 736
 737                 if (ext->rs_left <= ext->rs_failed) {
 738                         ext->rs_failed = 0;
 739                         return true;
 740                 }
 741         } else if (mode != SET_OUT_OF_SYNC) {
 742                 /* be quiet if lc_find() did not find it. */
 743                 drbd_err(device, "lc_get() failed! locked=%d/%d flags=%lu\n",
 744                     device->resync_locked,
 745                     device->resync->nr_elements,
 746                     device->resync->flags);
 747         }
 748         return false;
 749 }
 750
 751 void drbd_advance_rs_marks(struct drbd_device *device, unsigned long still_to_go)
 752 {
 753         unsigned long now = jiffies;
 754         unsigned long last = device->rs_mark_time[device->rs_last_mark];
 755         int next = (device->rs_last_mark + 1) % DRBD_SYNC_MARKS;
 756         if (time_after_eq(now, last + DRBD_SYNC_MARK_STEP)) {
 757                 if (device->rs_mark_left[device->rs_last_mark] != still_to_go &&
 758                     device->state.conn != C_PAUSED_SYNC_T &&
 759                     device->state.conn != C_PAUSED_SYNC_S) {
 760                         device->rs_mark_time[next] = now;
 761                         device->rs_mark_left[next] = still_to_go;
 762                         device->rs_last_mark = next;
 763                 }
 764         }
 765 }
 766
 767 /* It is called lazy update, so don't do write-out too often. */
 768 static bool lazy_bitmap_update_due(struct drbd_device *device)
 769 {
 770         return time_after(jiffies, device->rs_last_bcast + 2*HZ);
 771 }
 772
 773 static void maybe_schedule_on_disk_bitmap_update(struct drbd_device *device, bool rs_done)
 774 {
 775         if (rs_done) {
 776                 struct drbd_connection *connection = first_peer_device(device)->connection;
 777                 if (connection->agreed_pro_version <= 95 ||
 778                     is_sync_target_state(device->state.conn))
 779                         set_bit(RS_DONE, &device->flags);
 780                         /* and also set RS_PROGRESS below */
 781
 782                 /* Else: rather wait for explicit notification via receive_state,
 783                  * to avoid uuids-rotated-too-fast causing full resync
 784                  * in next handshake, in case the replication link breaks
 785                  * at the most unfortunate time... */
 786         } else if (!lazy_bitmap_update_due(device))
 787                 return;
 788
 789         drbd_device_post_work(device, RS_PROGRESS);
 790 }
 791
 792 static int update_sync_bits(struct drbd_device *device,
 793                 unsigned long sbnr, unsigned long ebnr,
 794                 enum update_sync_bits_mode mode)
 795 {
 796         /*
 797          * We keep a count of set bits per resync-extent in the ->rs_left
 798          * caching member, so we need to loop and work within the resync extent
 799          * alignment. Typically this loop will execute exactly once.
 800          */
 801         unsigned long flags;
 802         unsigned long count = 0;
 803         unsigned int cleared = 0;
 804         while (sbnr <= ebnr) {
 805                 /* set temporary boundary bit number to last bit number within
 806                  * the resync extent of the current start bit number,
 807                  * but cap at provided end bit number */
 808                 unsigned long tbnr = min(ebnr, sbnr | BM_BLOCKS_PER_BM_EXT_MASK);
 809                 unsigned long c;
 810
 811                 if (mode == RECORD_RS_FAILED)
 812                         /* Only called from drbd_rs_failed_io(), bits
 813                          * supposedly still set.  Recount, maybe some
 814                          * of the bits have been successfully cleared
 815                          * by application IO meanwhile.
 816                          */
 817                         c = drbd_bm_count_bits(device, sbnr, tbnr);
 818                 else if (mode == SET_IN_SYNC)
 819                         c = drbd_bm_clear_bits(device, sbnr, tbnr);
 820                 else /* if (mode == SET_OUT_OF_SYNC) */
 821                         c = drbd_bm_set_bits(device, sbnr, tbnr);
 822
 823                 if (c) {
 824                         spin_lock_irqsave(&device->al_lock, flags);
 825                         cleared += update_rs_extent(device, BM_BIT_TO_EXT(sbnr), c, mode);
 826                         spin_unlock_irqrestore(&device->al_lock, flags);
 827                         count += c;
 828                 }
 829                 sbnr = tbnr + 1;
 830         }
 831         if (count) {
 832                 if (mode == SET_IN_SYNC) {
 833                         unsigned long still_to_go = drbd_bm_total_weight(device);
 834                         bool rs_is_done = (still_to_go <= device->rs_failed);
 835                         drbd_advance_rs_marks(device, still_to_go);
 836                         if (cleared || rs_is_done)
 837                                 maybe_schedule_on_disk_bitmap_update(device, rs_is_done);
 838                 } else if (mode == RECORD_RS_FAILED)
 839                         device->rs_failed += count;
 840                 wake_up(&device->al_wait);
 841         }
 842         return count;
 843 }
 844
 845 static bool plausible_request_size(int size)
 846 {
 847         return size > 0
 848                 && size <= DRBD_MAX_BATCH_BIO_SIZE
 849                 && IS_ALIGNED(size, 512);
 850 }
 851
 852 /* clear the bit corresponding to the piece of storage in question:
 853  * size byte of data starting from sector.  Only clear a bits of the affected
 854  * one ore more _aligned_ BM_BLOCK_SIZE blocks.
 855  *
 856  * called by worker on C_SYNC_TARGET and receiver on SyncSource.
 857  *
 858  */
 859 int __drbd_change_sync(struct drbd_device *device, sector_t sector, int size,
 860                 enum update_sync_bits_mode mode)
 861 {
 862         /* Is called from worker and receiver context _only_ */
 863         unsigned long sbnr, ebnr, lbnr;
 864         unsigned long count = 0;
 865         sector_t esector, nr_sectors;
 866
 867         /* This would be an empty REQ_PREFLUSH, be silent. */
 868         if ((mode == SET_OUT_OF_SYNC) && size == 0)
 869                 return 0;
 870
 871         if (!plausible_request_size(size)) {
 872                 drbd_err(device, "%s: sector=%llus size=%d nonsense!\n",
 873                                 drbd_change_sync_fname[mode],
 874                                 (unsigned long long)sector, size);
 875                 return 0;
 876         }
 877
 878         if (!get_ldev(device))
 879                 return 0; /* no disk, no metadata, no bitmap to manipulate bits in */
 880
 881         nr_sectors = drbd_get_capacity(device->this_bdev);
 882         esector = sector + (size >> 9) - 1;
 883
 884         if (!expect(sector < nr_sectors))
 885                 goto out;
 886         if (!expect(esector < nr_sectors))
 887                 esector = nr_sectors - 1;
 888
 889         lbnr = BM_SECT_TO_BIT(nr_sectors-1);
 890
 891         if (mode == SET_IN_SYNC) {
 892                 /* Round up start sector, round down end sector.  We make sure
 893                  * we only clear full, aligned, BM_BLOCK_SIZE blocks. */
 894                 if (unlikely(esector < BM_SECT_PER_BIT-1))
 895                         goto out;
 896                 if (unlikely(esector == (nr_sectors-1)))
 897                         ebnr = lbnr;
 898                 else
 899                         ebnr = BM_SECT_TO_BIT(esector - (BM_SECT_PER_BIT-1));
 900                 sbnr = BM_SECT_TO_BIT(sector + BM_SECT_PER_BIT-1);
 901         } else {
 902                 /* We set it out of sync, or record resync failure.
 903                  * Should not round anything here. */
 904                 sbnr = BM_SECT_TO_BIT(sector);
 905                 ebnr = BM_SECT_TO_BIT(esector);
 906         }
 907
 908         count = update_sync_bits(device, sbnr, ebnr, mode);
 909 out:
 910         put_ldev(device);
 911         return count;
 912 }
 913
 914 static
 915 struct bm_extent *_bme_get(struct drbd_device *device, unsigned int enr)
 916 {
 917         struct lc_element *e;
 918         struct bm_extent *bm_ext;
 919         int wakeup = 0;
 920         unsigned long rs_flags;
 921
 922         spin_lock_irq(&device->al_lock);
 923         if (device->resync_locked > device->resync->nr_elements/2) {
 924                 spin_unlock_irq(&device->al_lock);
 925                 return NULL;
 926         }
 927         e = lc_get(device->resync, enr);
 928         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
 929         if (bm_ext) {
 930                 if (bm_ext->lce.lc_number != enr) {
 931                         bm_ext->rs_left = drbd_bm_e_weight(device, enr);
 932                         bm_ext->rs_failed = 0;
 933                         lc_committed(device->resync);
 934                         wakeup = 1;
 935                 }
 936                 if (bm_ext->lce.refcnt == 1)
 937                         device->resync_locked++;
 938                 set_bit(BME_NO_WRITES, &bm_ext->flags);
 939         }
 940         rs_flags = device->resync->flags;
 941         spin_unlock_irq(&device->al_lock);
 942         if (wakeup)
 943                 wake_up(&device->al_wait);
 944
 945         if (!bm_ext) {
 946                 if (rs_flags & LC_STARVING)
 947                         drbd_warn(device, "Have to wait for element"
 948                              " (resync LRU too small?)\n");
 949                 BUG_ON(rs_flags & LC_LOCKED);
 950         }
 951
 952         return bm_ext;
 953 }
 954
 955 static int _is_in_al(struct drbd_device *device, unsigned int enr)
 956 {
 957         int rv;
 958
 959         spin_lock_irq(&device->al_lock);
 960         rv = lc_is_used(device->act_log, enr);
 961         spin_unlock_irq(&device->al_lock);
 962
 963         return rv;
 964 }
 965
 966 /**
 967  * drbd_rs_begin_io() - Gets an extent in the resync LRU cache and sets it to BME_LOCKED
 968  * @device:     DRBD device.
 969  * @sector:     The sector number.
 970  *
 971  * This functions sleeps on al_wait. Returns 0 on success, -EINTR if interrupted.
 972  */
 973 int drbd_rs_begin_io(struct drbd_device *device, sector_t sector)
 974 {
 975         unsigned int enr = BM_SECT_TO_EXT(sector);
 976         struct bm_extent *bm_ext;
 977         int i, sig;
 978         bool sa;
 979
 980 retry:
 981         sig = wait_event_interruptible(device->al_wait,
 982                         (bm_ext = _bme_get(device, enr)));
 983         if (sig)
 984                 return -EINTR;
 985
 986         if (test_bit(BME_LOCKED, &bm_ext->flags))
 987                 return 0;
 988
 989         /* step aside only while we are above c-min-rate; unless disabled. */
 990         sa = drbd_rs_c_min_rate_throttle(device);
 991
 992         for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
 993                 sig = wait_event_interruptible(device->al_wait,
 994                                                !_is_in_al(device, enr * AL_EXT_PER_BM_SECT + i) ||
 995                                                (sa && test_bit(BME_PRIORITY, &bm_ext->flags)));
 996
 997                 if (sig || (sa && test_bit(BME_PRIORITY, &bm_ext->flags))) {
 998                         spin_lock_irq(&device->al_lock);
 999                         if (lc_put(device->resync, &bm_ext->lce) == 0) {
1000                                 bm_ext->flags = 0; /* clears BME_NO_WRITES and eventually BME_PRIORITY */
1001                                 device->resync_locked--;
1002                                 wake_up(&device->al_wait);
1003                         }
1004                         spin_unlock_irq(&device->al_lock);
1005                         if (sig)
1006                                 return -EINTR;
1007                         if (schedule_timeout_interruptible(HZ/10))
1008                                 return -EINTR;
1009                         goto retry;
1010                 }
1011         }
1012         set_bit(BME_LOCKED, &bm_ext->flags);
1013         return 0;
1014 }
1015
1016 /**
1017  * drbd_try_rs_begin_io() - Gets an extent in the resync LRU cache, does not sleep
1018  * @device:     DRBD device.
1019  * @sector:     The sector number.
1020  *
1021  * Gets an extent in the resync LRU cache, sets it to BME_NO_WRITES, then
1022  * tries to set it to BME_LOCKED. Returns 0 upon success, and -EAGAIN
1023  * if there is still application IO going on in this area.
1024  */
1025 int drbd_try_rs_begin_io(struct drbd_device *device, sector_t sector)
1026 {
1027         unsigned int enr = BM_SECT_TO_EXT(sector);
1028         const unsigned int al_enr = enr*AL_EXT_PER_BM_SECT;
1029         struct lc_element *e;
1030         struct bm_extent *bm_ext;
1031         int i;
1032         bool throttle = drbd_rs_should_slow_down(device, sector, true);
1033
1034         /* If we need to throttle, a half-locked (only marked BME_NO_WRITES,
1035          * not yet BME_LOCKED) extent needs to be kicked out explicitly if we
1036          * need to throttle. There is at most one such half-locked extent,
1037          * which is remembered in resync_wenr. */
1038
1039         if (throttle && device->resync_wenr != enr)
1040                 return -EAGAIN;
1041
1042         spin_lock_irq(&device->al_lock);
1043         if (device->resync_wenr != LC_FREE && device->resync_wenr != enr) {
1044                 /* in case you have very heavy scattered io, it may
1045                  * stall the syncer undefined if we give up the ref count
1046                  * when we try again and requeue.
1047                  *
1048                  * if we don't give up the refcount, but the next time
1049                  * we are scheduled this extent has been "synced" by new
1050                  * application writes, we'd miss the lc_put on the
1051                  * extent we keep the refcount on.
1052                  * so we remembered which extent we had to try again, and
1053                  * if the next requested one is something else, we do
1054                  * the lc_put here...
1055                  * we also have to wake_up
1056                  */
1057                 e = lc_find(device->resync, device->resync_wenr);
1058                 bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1059                 if (bm_ext) {
1060                         D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1061                         D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1062                         clear_bit(BME_NO_WRITES, &bm_ext->flags);
1063                         device->resync_wenr = LC_FREE;
1064                         if (lc_put(device->resync, &bm_ext->lce) == 0) {
1065                                 bm_ext->flags = 0;
1066                                 device->resync_locked--;
1067                         }
1068                         wake_up(&device->al_wait);
1069                 } else {
1070                         drbd_alert(device, "LOGIC BUG\n");
1071                 }
1072         }
1073         /* TRY. */
1074         e = lc_try_get(device->resync, enr);
1075         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1076         if (bm_ext) {
1077                 if (test_bit(BME_LOCKED, &bm_ext->flags))
1078                         goto proceed;
1079                 if (!test_and_set_bit(BME_NO_WRITES, &bm_ext->flags)) {
1080                         device->resync_locked++;
1081                 } else {
1082                         /* we did set the BME_NO_WRITES,
1083                          * but then could not set BME_LOCKED,
1084                          * so we tried again.
1085                          * drop the extra reference. */
1086                         bm_ext->lce.refcnt--;
1087                         D_ASSERT(device, bm_ext->lce.refcnt > 0);
1088                 }
1089                 goto check_al;
1090         } else {
1091                 /* do we rather want to try later? */
1092                 if (device->resync_locked > device->resync->nr_elements-3)
1093                         goto try_again;
1094                 /* Do or do not. There is no try. -- Yoda */
1095                 e = lc_get(device->resync, enr);
1096                 bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1097                 if (!bm_ext) {
1098                         const unsigned long rs_flags = device->resync->flags;
1099                         if (rs_flags & LC_STARVING)
1100                                 drbd_warn(device, "Have to wait for element"
1101                                      " (resync LRU too small?)\n");
1102                         BUG_ON(rs_flags & LC_LOCKED);
1103                         goto try_again;
1104                 }
1105                 if (bm_ext->lce.lc_number != enr) {
1106                         bm_ext->rs_left = drbd_bm_e_weight(device, enr);
1107                         bm_ext->rs_failed = 0;
1108                         lc_committed(device->resync);
1109                         wake_up(&device->al_wait);
1110                         D_ASSERT(device, test_bit(BME_LOCKED, &bm_ext->flags) == 0);
1111                 }
1112                 set_bit(BME_NO_WRITES, &bm_ext->flags);
1113                 D_ASSERT(device, bm_ext->lce.refcnt == 1);
1114                 device->resync_locked++;
1115                 goto check_al;
1116         }
1117 check_al:
1118         for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
1119                 if (lc_is_used(device->act_log, al_enr+i))
1120                         goto try_again;
1121         }
1122         set_bit(BME_LOCKED, &bm_ext->flags);
1123 proceed:
1124         device->resync_wenr = LC_FREE;
1125         spin_unlock_irq(&device->al_lock);
1126         return 0;
1127
1128 try_again:
1129         if (bm_ext) {
1130                 if (throttle) {
1131                         D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1132                         D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1133                         clear_bit(BME_NO_WRITES, &bm_ext->flags);
1134                         device->resync_wenr = LC_FREE;
1135                         if (lc_put(device->resync, &bm_ext->lce) == 0) {
1136                                 bm_ext->flags = 0;
1137                                 device->resync_locked--;
1138                         }
1139                         wake_up(&device->al_wait);
1140                 } else
1141                         device->resync_wenr = enr;
1142         }
1143         spin_unlock_irq(&device->al_lock);
1144         return -EAGAIN;
1145 }
1146
1147 void drbd_rs_complete_io(struct drbd_device *device, sector_t sector)
1148 {
1149         unsigned int enr = BM_SECT_TO_EXT(sector);
1150         struct lc_element *e;
1151         struct bm_extent *bm_ext;
1152         unsigned long flags;
1153
1154         spin_lock_irqsave(&device->al_lock, flags);
1155         e = lc_find(device->resync, enr);
1156         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1157         if (!bm_ext) {
1158                 spin_unlock_irqrestore(&device->al_lock, flags);
1159                 if (__ratelimit(&drbd_ratelimit_state))
1160                         drbd_err(device, "drbd_rs_complete_io() called, but extent not found\n");
1161                 return;
1162         }
1163
1164         if (bm_ext->lce.refcnt == 0) {
1165                 spin_unlock_irqrestore(&device->al_lock, flags);
1166                 drbd_err(device, "drbd_rs_complete_io(,%llu [=%u]) called, "
1167                     "but refcnt is 0!?\n",
1168                     (unsigned long long)sector, enr);
1169                 return;
1170         }
1171
1172         if (lc_put(device->resync, &bm_ext->lce) == 0) {
1173                 bm_ext->flags = 0; /* clear BME_LOCKED, BME_NO_WRITES and BME_PRIORITY */
1174                 device->resync_locked--;
1175                 wake_up(&device->al_wait);
1176         }
1177
1178         spin_unlock_irqrestore(&device->al_lock, flags);
1179 }
1180
1181 /**
1182  * drbd_rs_cancel_all() - Removes all extents from the resync LRU (even BME_LOCKED)
1183  * @device:     DRBD device.
1184  */
1185 void drbd_rs_cancel_all(struct drbd_device *device)
1186 {
1187         spin_lock_irq(&device->al_lock);
1188
1189         if (get_ldev_if_state(device, D_FAILED)) { /* Makes sure ->resync is there. */
1190                 lc_reset(device->resync);
1191                 put_ldev(device);
1192         }
1193         device->resync_locked = 0;
1194         device->resync_wenr = LC_FREE;
1195         spin_unlock_irq(&device->al_lock);
1196         wake_up(&device->al_wait);
1197 }
1198
1199 /**
1200  * drbd_rs_del_all() - Gracefully remove all extents from the resync LRU
1201  * @device:     DRBD device.
1202  *
1203  * Returns 0 upon success, -EAGAIN if at least one reference count was
1204  * not zero.
1205  */
1206 int drbd_rs_del_all(struct drbd_device *device)
1207 {
1208         struct lc_element *e;
1209         struct bm_extent *bm_ext;
1210         int i;
1211
1212         spin_lock_irq(&device->al_lock);
1213
1214         if (get_ldev_if_state(device, D_FAILED)) {
1215                 /* ok, ->resync is there. */
1216                 for (i = 0; i < device->resync->nr_elements; i++) {
1217                         e = lc_element_by_index(device->resync, i);
1218                         bm_ext = lc_entry(e, struct bm_extent, lce);
1219                         if (bm_ext->lce.lc_number == LC_FREE)
1220                                 continue;
1221                         if (bm_ext->lce.lc_number == device->resync_wenr) {
1222                                 drbd_info(device, "dropping %u in drbd_rs_del_all, apparently"
1223                                      " got 'synced' by application io\n",
1224                                      device->resync_wenr);
1225                                 D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1226                                 D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1227                                 clear_bit(BME_NO_WRITES, &bm_ext->flags);
1228                                 device->resync_wenr = LC_FREE;
1229                                 lc_put(device->resync, &bm_ext->lce);
1230                         }
1231                         if (bm_ext->lce.refcnt != 0) {
1232                                 drbd_info(device, "Retrying drbd_rs_del_all() later. "
1233                                      "refcnt=%d\n", bm_ext->lce.refcnt);
1234                                 put_ldev(device);
1235                                 spin_unlock_irq(&device->al_lock);
1236                                 return -EAGAIN;
1237                         }
1238                         D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1239                         D_ASSERT(device, !test_bit(BME_NO_WRITES, &bm_ext->flags));
1240                         lc_del(device->resync, &bm_ext->lce);
1241                 }
1242                 D_ASSERT(device, device->resync->used == 0);
1243                 put_ldev(device);
1244         }
1245         spin_unlock_irq(&device->al_lock);
1246         wake_up(&device->al_wait);
1247
1248         return 0;
1249 }