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