linux/drivers/block/drbd/drbd_actlog.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3   drbd_actlog.c
   4
   5   This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
   6
   7   Copyright (C) 2003-2008, LINBIT Information Technologies GmbH.
   8   Copyright (C) 2003-2008, Philipp Reisner <philipp.reisner@linbit.com>.
   9   Copyright (C) 2003-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
  10
  11
  12 */
  13
  14#include <linux/slab.h>
  15#include <linux/crc32c.h>
  16#include <linux/drbd.h>
  17#include <linux/drbd_limits.h>
  18#include "drbd_int.h"
  19
  20
  21enum al_transaction_types {
  22        AL_TR_UPDATE = 0,
  23        AL_TR_INITIALIZED = 0xffff
  24};
  25/* all fields on disc in big endian */
  26struct __packed al_transaction_on_disk {
  27        /* don't we all like magic */
  28        __be32  magic;
  29
  30        /* to identify the most recent transaction block
  31         * in the on disk ring buffer */
  32        __be32  tr_number;
  33
  34        /* checksum on the full 4k block, with this field set to 0. */
  35        __be32  crc32c;
  36
  37        /* type of transaction, special transaction types like:
  38         * purge-all, set-all-idle, set-all-active, ... to-be-defined
  39         * see also enum al_transaction_types */
  40        __be16  transaction_type;
  41
  42        /* we currently allow only a few thousand extents,
  43         * so 16bit will be enough for the slot number. */
  44
  45        /* how many updates in this transaction */
  46        __be16  n_updates;
  47
  48        /* maximum slot number, "al-extents" in drbd.conf speak.
  49         * Having this in each transaction should make reconfiguration
  50         * of that parameter easier. */
  51        __be16  context_size;
  52
  53        /* slot number the context starts with */
  54        __be16  context_start_slot_nr;
  55
  56        /* Some reserved bytes.  Expected usage is a 64bit counter of
  57         * sectors-written since device creation, and other data generation tag
  58         * supporting usage */
  59        __be32  __reserved[4];
  60
  61        /* --- 36 byte used --- */
  62
  63        /* Reserve space for up to AL_UPDATES_PER_TRANSACTION changes
  64         * in one transaction, then use the remaining byte in the 4k block for
  65         * context information.  "Flexible" number of updates per transaction
  66         * does not help, as we have to account for the case when all update
  67         * slots are used anyways, so it would only complicate code without
  68         * additional benefit.
  69         */
  70        __be16  update_slot_nr[AL_UPDATES_PER_TRANSACTION];
  71
  72        /* but the extent number is 32bit, which at an extent size of 4 MiB
  73         * allows to cover device sizes of up to 2**54 Byte (16 PiB) */
  74        __be32  update_extent_nr[AL_UPDATES_PER_TRANSACTION];
  75
  76        /* --- 420 bytes used (36 + 64*6) --- */
  77
  78        /* 4096 - 420 = 3676 = 919 * 4 */
  79        __be32  context[AL_CONTEXT_PER_TRANSACTION];
  80};
  81
  82void *drbd_md_get_buffer(struct drbd_device *device, const char *intent)
  83{
  84        int r;
  85
  86        wait_event(device->misc_wait,
  87                   (r = atomic_cmpxchg(&device->md_io.in_use, 0, 1)) == 0 ||
  88                   device->state.disk <= D_FAILED);
  89
  90        if (r)
  91                return NULL;
  92
  93        device->md_io.current_use = intent;
  94        device->md_io.start_jif = jiffies;
  95        device->md_io.submit_jif = device->md_io.start_jif - 1;
  96        return page_address(device->md_io.page);
  97}
  98
  99void drbd_md_put_buffer(struct drbd_device *device)
 100{
 101        if (atomic_dec_and_test(&device->md_io.in_use))
 102                wake_up(&device->misc_wait);
 103}
 104
 105void wait_until_done_or_force_detached(struct drbd_device *device, struct drbd_backing_dev *bdev,
 106                                     unsigned int *done)
 107{
 108        long dt;
 109
 110        rcu_read_lock();
 111        dt = rcu_dereference(bdev->disk_conf)->disk_timeout;
 112        rcu_read_unlock();
 113        dt = dt * HZ / 10;
 114        if (dt == 0)
 115                dt = MAX_SCHEDULE_TIMEOUT;
 116
 117        dt = wait_event_timeout(device->misc_wait,
 118                        *done || test_bit(FORCE_DETACH, &device->flags), dt);
 119        if (dt == 0) {
 120                drbd_err(device, "meta-data IO operation timed out\n");
 121                drbd_chk_io_error(device, 1, DRBD_FORCE_DETACH);
 122        }
 123}
 124
 125static int _drbd_md_sync_page_io(struct drbd_device *device,
 126                                 struct drbd_backing_dev *bdev,
 127                                 sector_t sector, int op)
 128{
 129        struct bio *bio;
 130        /* we do all our meta data IO in aligned 4k blocks. */
 131        const int size = 4096;
 132        int err, op_flags = 0;
 133
 134        device->md_io.done = 0;
 135        device->md_io.error = -ENODEV;
 136
 137        if ((op == REQ_OP_WRITE) && !test_bit(MD_NO_FUA, &device->flags))
 138                op_flags |= REQ_FUA | REQ_PREFLUSH;
 139        op_flags |= REQ_SYNC;
 140
 141        bio = bio_alloc_bioset(GFP_NOIO, 1, &drbd_md_io_bio_set);
 142        bio_set_dev(bio, bdev->md_bdev);
 143        bio->bi_iter.bi_sector = sector;
 144        err = -EIO;
 145        if (bio_add_page(bio, device->md_io.page, size, 0) != size)
 146                goto out;
 147        bio->bi_private = device;
 148        bio->bi_end_io = drbd_md_endio;
 149        bio_set_op_attrs(bio, op, op_flags);
 150
 151        if (op != REQ_OP_WRITE && device->state.disk == D_DISKLESS && device->ldev == NULL)
 152                /* special case, drbd_md_read() during drbd_adm_attach(): no get_ldev */
 153                ;
 154        else if (!get_ldev_if_state(device, D_ATTACHING)) {
 155                /* Corresponding put_ldev in drbd_md_endio() */
 156                drbd_err(device, "ASSERT FAILED: get_ldev_if_state() == 1 in _drbd_md_sync_page_io()\n");
 157                err = -ENODEV;
 158                goto out;
 159        }
 160
 161        bio_get(bio); /* one bio_put() is in the completion handler */
 162        atomic_inc(&device->md_io.in_use); /* drbd_md_put_buffer() is in the completion handler */
 163        device->md_io.submit_jif = jiffies;
 164        if (drbd_insert_fault(device, (op == REQ_OP_WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))
 165                bio_io_error(bio);
 166        else
 167                submit_bio(bio);
 168        wait_until_done_or_force_detached(device, bdev, &device->md_io.done);
 169        if (!bio->bi_status)
 170                err = device->md_io.error;
 171
 172 out:
 173        bio_put(bio);
 174        return err;
 175}
 176
 177int drbd_md_sync_page_io(struct drbd_device *device, struct drbd_backing_dev *bdev,
 178                         sector_t sector, int op)
 179{
 180        int err;
 181        D_ASSERT(device, atomic_read(&device->md_io.in_use) == 1);
 182
 183        BUG_ON(!bdev->md_bdev);
 184
 185        dynamic_drbd_dbg(device, "meta_data io: %s [%d]:%s(,%llus,%s) %pS\n",
 186             current->comm, current->pid, __func__,
 187             (unsigned long long)sector, (op == REQ_OP_WRITE) ? "WRITE" : "READ",
 188             (void*)_RET_IP_ );
 189
 190        if (sector < drbd_md_first_sector(bdev) ||
 191            sector + 7 > drbd_md_last_sector(bdev))
 192                drbd_alert(device, "%s [%d]:%s(,%llus,%s) out of range md access!\n",
 193                     current->comm, current->pid, __func__,
 194                     (unsigned long long)sector,
 195                     (op == REQ_OP_WRITE) ? "WRITE" : "READ");
 196
 197        err = _drbd_md_sync_page_io(device, bdev, sector, op);
 198        if (err) {
 199                drbd_err(device, "drbd_md_sync_page_io(,%llus,%s) failed with error %d\n",
 200                    (unsigned long long)sector,
 201                    (op == REQ_OP_WRITE) ? "WRITE" : "READ", err);
 202        }
 203        return err;
 204}
 205
 206static struct bm_extent *find_active_resync_extent(struct drbd_device *device, unsigned int enr)
 207{
 208        struct lc_element *tmp;
 209        tmp = lc_find(device->resync, enr/AL_EXT_PER_BM_SECT);
 210        if (unlikely(tmp != NULL)) {
 211                struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
 212                if (test_bit(BME_NO_WRITES, &bm_ext->flags))
 213                        return bm_ext;
 214        }
 215        return NULL;
 216}
 217
 218static struct lc_element *_al_get(struct drbd_device *device, unsigned int enr, bool nonblock)
 219{
 220        struct lc_element *al_ext;
 221        struct bm_extent *bm_ext;
 222        int wake;
 223
 224        spin_lock_irq(&device->al_lock);
 225        bm_ext = find_active_resync_extent(device, enr);
 226        if (bm_ext) {
 227                wake = !test_and_set_bit(BME_PRIORITY, &bm_ext->flags);
 228                spin_unlock_irq(&device->al_lock);
 229                if (wake)
 230                        wake_up(&device->al_wait);
 231                return NULL;
 232        }
 233        if (nonblock)
 234                al_ext = lc_try_get(device->act_log, enr);
 235        else
 236                al_ext = lc_get(device->act_log, enr);
 237        spin_unlock_irq(&device->al_lock);
 238        return al_ext;
 239}
 240
 241bool drbd_al_begin_io_fastpath(struct drbd_device *device, struct drbd_interval *i)
 242{
 243        /* for bios crossing activity log extent boundaries,
 244         * we may need to activate two extents in one go */
 245        unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 246        unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 247
 248        D_ASSERT(device, first <= last);
 249        D_ASSERT(device, atomic_read(&device->local_cnt) > 0);
 250
 251        /* FIXME figure out a fast path for bios crossing AL extent boundaries */
 252        if (first != last)
 253                return false;
 254
 255        return _al_get(device, first, true);
 256}
 257
 258bool drbd_al_begin_io_prepare(struct drbd_device *device, struct drbd_interval *i)
 259{
 260        /* for bios crossing activity log extent boundaries,
 261         * we may need to activate two extents in one go */
 262        unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 263        unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 264        unsigned enr;
 265        bool need_transaction = false;
 266
 267        D_ASSERT(device, first <= last);
 268        D_ASSERT(device, atomic_read(&device->local_cnt) > 0);
 269
 270        for (enr = first; enr <= last; enr++) {
 271                struct lc_element *al_ext;
 272                wait_event(device->al_wait,
 273                                (al_ext = _al_get(device, enr, false)) != NULL);
 274                if (al_ext->lc_number != enr)
 275                        need_transaction = true;
 276        }
 277        return need_transaction;
 278}
 279
 280#if (PAGE_SHIFT + 3) < (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT)
 281/* Currently BM_BLOCK_SHIFT, BM_EXT_SHIFT and AL_EXTENT_SHIFT
 282 * are still coupled, or assume too much about their relation.
 283 * Code below will not work if this is violated.
 284 * Will be cleaned up with some followup patch.
 285 */
 286# error FIXME
 287#endif
 288
 289static unsigned int al_extent_to_bm_page(unsigned int al_enr)
 290{
 291        return al_enr >>
 292                /* bit to page */
 293                ((PAGE_SHIFT + 3) -
 294                /* al extent number to bit */
 295                 (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT));
 296}
 297
 298static sector_t al_tr_number_to_on_disk_sector(struct drbd_device *device)
 299{
 300        const unsigned int stripes = device->ldev->md.al_stripes;
 301        const unsigned int stripe_size_4kB = device->ldev->md.al_stripe_size_4k;
 302
 303        /* transaction number, modulo on-disk ring buffer wrap around */
 304        unsigned int t = device->al_tr_number % (device->ldev->md.al_size_4k);
 305
 306        /* ... to aligned 4k on disk block */
 307        t = ((t % stripes) * stripe_size_4kB) + t/stripes;
 308
 309        /* ... to 512 byte sector in activity log */
 310        t *= 8;
 311
 312        /* ... plus offset to the on disk position */
 313        return device->ldev->md.md_offset + device->ldev->md.al_offset + t;
 314}
 315
 316static int __al_write_transaction(struct drbd_device *device, struct al_transaction_on_disk *buffer)
 317{
 318        struct lc_element *e;
 319        sector_t sector;
 320        int i, mx;
 321        unsigned extent_nr;
 322        unsigned crc = 0;
 323        int err = 0;
 324
 325        memset(buffer, 0, sizeof(*buffer));
 326        buffer->magic = cpu_to_be32(DRBD_AL_MAGIC);
 327        buffer->tr_number = cpu_to_be32(device->al_tr_number);
 328
 329        i = 0;
 330
 331        drbd_bm_reset_al_hints(device);
 332
 333        /* Even though no one can start to change this list
 334         * once we set the LC_LOCKED -- from drbd_al_begin_io(),
 335         * lc_try_lock_for_transaction() --, someone may still
 336         * be in the process of changing it. */
 337        spin_lock_irq(&device->al_lock);
 338        list_for_each_entry(e, &device->act_log->to_be_changed, list) {
 339                if (i == AL_UPDATES_PER_TRANSACTION) {
 340                        i++;
 341                        break;
 342                }
 343                buffer->update_slot_nr[i] = cpu_to_be16(e->lc_index);
 344                buffer->update_extent_nr[i] = cpu_to_be32(e->lc_new_number);
 345                if (e->lc_number != LC_FREE)
 346                        drbd_bm_mark_for_writeout(device,
 347                                        al_extent_to_bm_page(e->lc_number));
 348                i++;
 349        }
 350        spin_unlock_irq(&device->al_lock);
 351        BUG_ON(i > AL_UPDATES_PER_TRANSACTION);
 352
 353        buffer->n_updates = cpu_to_be16(i);
 354        for ( ; i < AL_UPDATES_PER_TRANSACTION; i++) {
 355                buffer->update_slot_nr[i] = cpu_to_be16(-1);
 356                buffer->update_extent_nr[i] = cpu_to_be32(LC_FREE);
 357        }
 358
 359        buffer->context_size = cpu_to_be16(device->act_log->nr_elements);
 360        buffer->context_start_slot_nr = cpu_to_be16(device->al_tr_cycle);
 361
 362        mx = min_t(int, AL_CONTEXT_PER_TRANSACTION,
 363                   device->act_log->nr_elements - device->al_tr_cycle);
 364        for (i = 0; i < mx; i++) {
 365                unsigned idx = device->al_tr_cycle + i;
 366                extent_nr = lc_element_by_index(device->act_log, idx)->lc_number;
 367                buffer->context[i] = cpu_to_be32(extent_nr);
 368        }
 369        for (; i < AL_CONTEXT_PER_TRANSACTION; i++)
 370                buffer->context[i] = cpu_to_be32(LC_FREE);
 371
 372        device->al_tr_cycle += AL_CONTEXT_PER_TRANSACTION;
 373        if (device->al_tr_cycle >= device->act_log->nr_elements)
 374                device->al_tr_cycle = 0;
 375
 376        sector = al_tr_number_to_on_disk_sector(device);
 377
 378        crc = crc32c(0, buffer, 4096);
 379        buffer->crc32c = cpu_to_be32(crc);
 380
 381        if (drbd_bm_write_hinted(device))
 382                err = -EIO;
 383        else {
 384                bool write_al_updates;
 385                rcu_read_lock();
 386                write_al_updates = rcu_dereference(device->ldev->disk_conf)->al_updates;
 387                rcu_read_unlock();
 388                if (write_al_updates) {
 389                        if (drbd_md_sync_page_io(device, device->ldev, sector, WRITE)) {
 390                                err = -EIO;
 391                                drbd_chk_io_error(device, 1, DRBD_META_IO_ERROR);
 392                        } else {
 393                                device->al_tr_number++;
 394                                device->al_writ_cnt++;
 395                        }
 396                }
 397        }
 398
 399        return err;
 400}
 401
 402static int al_write_transaction(struct drbd_device *device)
 403{
 404        struct al_transaction_on_disk *buffer;
 405        int err;
 406
 407        if (!get_ldev(device)) {
 408                drbd_err(device, "disk is %s, cannot start al transaction\n",
 409                        drbd_disk_str(device->state.disk));
 410                return -EIO;
 411        }
 412
 413        /* The bitmap write may have failed, causing a state change. */
 414        if (device->state.disk < D_INCONSISTENT) {
 415                drbd_err(device,
 416                        "disk is %s, cannot write al transaction\n",
 417                        drbd_disk_str(device->state.disk));
 418                put_ldev(device);
 419                return -EIO;
 420        }
 421
 422        /* protects md_io_buffer, al_tr_cycle, ... */
 423        buffer = drbd_md_get_buffer(device, __func__);
 424        if (!buffer) {
 425                drbd_err(device, "disk failed while waiting for md_io buffer\n");
 426                put_ldev(device);
 427                return -ENODEV;
 428        }
 429
 430        err = __al_write_transaction(device, buffer);
 431
 432        drbd_md_put_buffer(device);
 433        put_ldev(device);
 434
 435        return err;
 436}
 437
 438
 439void drbd_al_begin_io_commit(struct drbd_device *device)
 440{
 441        bool locked = false;
 442
 443        /* Serialize multiple transactions.
 444         * This uses test_and_set_bit, memory barrier is implicit.
 445         */
 446        wait_event(device->al_wait,
 447                        device->act_log->pending_changes == 0 ||
 448                        (locked = lc_try_lock_for_transaction(device->act_log)));
 449
 450        if (locked) {
 451                /* Double check: it may have been committed by someone else,
 452                 * while we have been waiting for the lock. */
 453                if (device->act_log->pending_changes) {
 454                        bool write_al_updates;
 455
 456                        rcu_read_lock();
 457                        write_al_updates = rcu_dereference(device->ldev->disk_conf)->al_updates;
 458                        rcu_read_unlock();
 459
 460                        if (write_al_updates)
 461                                al_write_transaction(device);
 462                        spin_lock_irq(&device->al_lock);
 463                        /* FIXME
 464                        if (err)
 465                                we need an "lc_cancel" here;
 466                        */
 467                        lc_committed(device->act_log);
 468                        spin_unlock_irq(&device->al_lock);
 469                }
 470                lc_unlock(device->act_log);
 471                wake_up(&device->al_wait);
 472        }
 473}
 474
 475/*
 476 * @delegate:   delegate activity log I/O to the worker thread
 477 */
 478void drbd_al_begin_io(struct drbd_device *device, struct drbd_interval *i)
 479{
 480        if (drbd_al_begin_io_prepare(device, i))
 481                drbd_al_begin_io_commit(device);
 482}
 483
 484int drbd_al_begin_io_nonblock(struct drbd_device *device, struct drbd_interval *i)
 485{
 486        struct lru_cache *al = device->act_log;
 487        /* for bios crossing activity log extent boundaries,
 488         * we may need to activate two extents in one go */
 489        unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 490        unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 491        unsigned nr_al_extents;
 492        unsigned available_update_slots;
 493        unsigned enr;
 494
 495        D_ASSERT(device, first <= last);
 496
 497        nr_al_extents = 1 + last - first; /* worst case: all touched extends are cold. */
 498        available_update_slots = min(al->nr_elements - al->used,
 499                                al->max_pending_changes - al->pending_changes);
 500
 501        /* We want all necessary updates for a given request within the same transaction
 502         * We could first check how many updates are *actually* needed,
 503         * and use that instead of the worst-case nr_al_extents */
 504        if (available_update_slots < nr_al_extents) {
 505                /* Too many activity log extents are currently "hot".
 506                 *
 507                 * If we have accumulated pending changes already,
 508                 * we made progress.
 509                 *
 510                 * If we cannot get even a single pending change through,
 511                 * stop the fast path until we made some progress,
 512                 * or requests to "cold" extents could be starved. */
 513                if (!al->pending_changes)
 514                        __set_bit(__LC_STARVING, &device->act_log->flags);
 515                return -ENOBUFS;
 516        }
 517
 518        /* Is resync active in this area? */
 519        for (enr = first; enr <= last; enr++) {
 520                struct lc_element *tmp;
 521                tmp = lc_find(device->resync, enr/AL_EXT_PER_BM_SECT);
 522                if (unlikely(tmp != NULL)) {
 523                        struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
 524                        if (test_bit(BME_NO_WRITES, &bm_ext->flags)) {
 525                                if (!test_and_set_bit(BME_PRIORITY, &bm_ext->flags))
 526                                        return -EBUSY;
 527                                return -EWOULDBLOCK;
 528                        }
 529                }
 530        }
 531
 532        /* Checkout the refcounts.
 533         * Given that we checked for available elements and update slots above,
 534         * this has to be successful. */
 535        for (enr = first; enr <= last; enr++) {
 536                struct lc_element *al_ext;
 537                al_ext = lc_get_cumulative(device->act_log, enr);
 538                if (!al_ext)
 539                        drbd_info(device, "LOGIC BUG for enr=%u\n", enr);
 540        }
 541        return 0;
 542}
 543
 544void drbd_al_complete_io(struct drbd_device *device, struct drbd_interval *i)
 545{
 546        /* for bios crossing activity log extent boundaries,
 547         * we may need to activate two extents in one go */
 548        unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 549        unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 550        unsigned enr;
 551        struct lc_element *extent;
 552        unsigned long flags;
 553
 554        D_ASSERT(device, first <= last);
 555        spin_lock_irqsave(&device->al_lock, flags);
 556
 557        for (enr = first; enr <= last; enr++) {
 558                extent = lc_find(device->act_log, enr);
 559                if (!extent) {
 560                        drbd_err(device, "al_complete_io() called on inactive extent %u\n", enr);
 561                        continue;
 562                }
 563                lc_put(device->act_log, extent);
 564        }
 565        spin_unlock_irqrestore(&device->al_lock, flags);
 566        wake_up(&device->al_wait);
 567}
 568
 569static int _try_lc_del(struct drbd_device *device, struct lc_element *al_ext)
 570{
 571        int rv;
 572
 573        spin_lock_irq(&device->al_lock);
 574        rv = (al_ext->refcnt == 0);
 575        if (likely(rv))
 576                lc_del(device->act_log, al_ext);
 577        spin_unlock_irq(&device->al_lock);
 578
 579        return rv;
 580}
 581
 582/**
 583 * drbd_al_shrink() - Removes all active extents form the activity log
 584 * @device:     DRBD device.
 585 *
 586 * Removes all active extents form the activity log, waiting until
 587 * the reference count of each entry dropped to 0 first, of course.
 588 *
 589 * You need to lock device->act_log with lc_try_lock() / lc_unlock()
 590 */
 591void drbd_al_shrink(struct drbd_device *device)
 592{
 593        struct lc_element *al_ext;
 594        int i;
 595
 596        D_ASSERT(device, test_bit(__LC_LOCKED, &device->act_log->flags));
 597
 598        for (i = 0; i < device->act_log->nr_elements; i++) {
 599                al_ext = lc_element_by_index(device->act_log, i);
 600                if (al_ext->lc_number == LC_FREE)
 601                        continue;
 602                wait_event(device->al_wait, _try_lc_del(device, al_ext));
 603        }
 604
 605        wake_up(&device->al_wait);
 606}
 607
 608int drbd_al_initialize(struct drbd_device *device, void *buffer)
 609{
 610        struct al_transaction_on_disk *al = buffer;
 611        struct drbd_md *md = &device->ldev->md;
 612        int al_size_4k = md->al_stripes * md->al_stripe_size_4k;
 613        int i;
 614
 615        __al_write_transaction(device, al);
 616        /* There may or may not have been a pending transaction. */
 617        spin_lock_irq(&device->al_lock);
 618        lc_committed(device->act_log);
 619        spin_unlock_irq(&device->al_lock);
 620
 621        /* The rest of the transactions will have an empty "updates" list, and
 622         * are written out only to provide the context, and to initialize the
 623         * on-disk ring buffer. */
 624        for (i = 1; i < al_size_4k; i++) {
 625                int err = __al_write_transaction(device, al);
 626                if (err)
 627                        return err;
 628        }
 629        return 0;
 630}
 631
 632static const char *drbd_change_sync_fname[] = {
 633        [RECORD_RS_FAILED] = "drbd_rs_failed_io",
 634        [SET_IN_SYNC] = "drbd_set_in_sync",
 635        [SET_OUT_OF_SYNC] = "drbd_set_out_of_sync"
 636};
 637
 638/* ATTENTION. The AL's extents are 4MB each, while the extents in the
 639 * resync LRU-cache are 16MB each.
 640 * The caller of this function has to hold an get_ldev() reference.
 641 *
 642 * Adjusts the caching members ->rs_left (success) or ->rs_failed (!success),
 643 * potentially pulling in (and recounting the corresponding bits)
 644 * this resync extent into the resync extent lru cache.
 645 *
 646 * Returns whether all bits have been cleared for this resync extent,
 647 * precisely: (rs_left <= rs_failed)
 648 *
 649 * TODO will be obsoleted once we have a caching lru of the on disk bitmap
 650 */
 651static bool update_rs_extent(struct drbd_device *device,
 652                unsigned int enr, int count,
 653                enum update_sync_bits_mode mode)
 654{
 655        struct lc_element *e;
 656
 657        D_ASSERT(device, atomic_read(&device->local_cnt));
 658
 659        /* When setting out-of-sync bits,
 660         * we don't need it cached (lc_find).
 661         * But if it is present in the cache,
 662         * we should update the cached bit count.
 663         * Otherwise, that extent should be in the resync extent lru cache
 664         * already -- or we want to pull it in if necessary -- (lc_get),
 665         * then update and check rs_left and rs_failed. */
 666        if (mode == SET_OUT_OF_SYNC)
 667                e = lc_find(device->resync, enr);
 668        else
 669                e = lc_get(device->resync, enr);
 670        if (e) {
 671                struct bm_extent *ext = lc_entry(e, struct bm_extent, lce);
 672                if (ext->lce.lc_number == enr) {
 673                        if (mode == SET_IN_SYNC)
 674                                ext->rs_left -= count;
 675                        else if (mode == SET_OUT_OF_SYNC)
 676                                ext->rs_left += count;
 677                        else
 678                                ext->rs_failed += count;
 679                        if (ext->rs_left < ext->rs_failed) {
 680                                drbd_warn(device, "BAD! enr=%u rs_left=%d "
 681                                    "rs_failed=%d count=%d cstate=%s\n",
 682                                     ext->lce.lc_number, ext->rs_left,
 683                                     ext->rs_failed, count,
 684                                     drbd_conn_str(device->state.conn));
 685
 686                                /* We don't expect to be able to clear more bits
 687                                 * than have been set when we originally counted
 688                                 * the set bits to cache that value in ext->rs_left.
 689                                 * Whatever the reason (disconnect during resync,
 690                                 * delayed local completion of an application write),
 691                                 * try to fix it up by recounting here. */
 692                                ext->rs_left = drbd_bm_e_weight(device, enr);
 693                        }
 694                } else {
 695                        /* Normally this element should be in the cache,
 696                         * since drbd_rs_begin_io() pulled it already in.
 697                         *
 698                         * But maybe an application write finished, and we set
 699                         * something outside the resync lru_cache in sync.
 700                         */
 701                        int rs_left = drbd_bm_e_weight(device, enr);
 702                        if (ext->flags != 0) {
 703                                drbd_warn(device, "changing resync lce: %d[%u;%02lx]"
 704                                     " -> %d[%u;00]\n",
 705                                     ext->lce.lc_number, ext->rs_left,
 706                                     ext->flags, enr, rs_left);
 707                                ext->flags = 0;
 708                        }
 709                        if (ext->rs_failed) {
 710                                drbd_warn(device, "Kicking resync_lru element enr=%u "
 711                                     "out with rs_failed=%d\n",
 712                                     ext->lce.lc_number, ext->rs_failed);
 713                        }
 714                        ext->rs_left = rs_left;
 715                        ext->rs_failed = (mode == RECORD_RS_FAILED) ? count : 0;
 716                        /* we don't keep a persistent log of the resync lru,
 717                         * we can commit any change right away. */
 718                        lc_committed(device->resync);
 719                }
 720                if (mode != SET_OUT_OF_SYNC)
 721                        lc_put(device->resync, &ext->lce);
 722                /* no race, we are within the al_lock! */
 723
 724                if (ext->rs_left <= ext->rs_failed) {
 725                        ext->rs_failed = 0;
 726                        return true;
 727                }
 728        } else if (mode != SET_OUT_OF_SYNC) {
 729                /* be quiet if lc_find() did not find it. */
 730                drbd_err(device, "lc_get() failed! locked=%d/%d flags=%lu\n",
 731                    device->resync_locked,
 732                    device->resync->nr_elements,
 733                    device->resync->flags);
 734        }
 735        return false;
 736}
 737
 738void drbd_advance_rs_marks(struct drbd_device *device, unsigned long still_to_go)
 739{
 740        unsigned long now = jiffies;
 741        unsigned long last = device->rs_mark_time[device->rs_last_mark];
 742        int next = (device->rs_last_mark + 1) % DRBD_SYNC_MARKS;
 743        if (time_after_eq(now, last + DRBD_SYNC_MARK_STEP)) {
 744                if (device->rs_mark_left[device->rs_last_mark] != still_to_go &&
 745                    device->state.conn != C_PAUSED_SYNC_T &&
 746                    device->state.conn != C_PAUSED_SYNC_S) {
 747                        device->rs_mark_time[next] = now;
 748                        device->rs_mark_left[next] = still_to_go;
 749                        device->rs_last_mark = next;
 750                }
 751        }
 752}
 753
 754/* It is called lazy update, so don't do write-out too often. */
 755static bool lazy_bitmap_update_due(struct drbd_device *device)
 756{
 757        return time_after(jiffies, device->rs_last_bcast + 2*HZ);
 758}
 759
 760static void maybe_schedule_on_disk_bitmap_update(struct drbd_device *device, bool rs_done)
 761{
 762        if (rs_done) {
 763                struct drbd_connection *connection = first_peer_device(device)->connection;
 764                if (connection->agreed_pro_version <= 95 ||
 765                    is_sync_target_state(device->state.conn))
 766                        set_bit(RS_DONE, &device->flags);
 767                        /* and also set RS_PROGRESS below */
 768
 769                /* Else: rather wait for explicit notification via receive_state,
 770                 * to avoid uuids-rotated-too-fast causing full resync
 771                 * in next handshake, in case the replication link breaks
 772                 * at the most unfortunate time... */
 773        } else if (!lazy_bitmap_update_due(device))
 774                return;
 775
 776        drbd_device_post_work(device, RS_PROGRESS);
 777}
 778
 779static int update_sync_bits(struct drbd_device *device,
 780                unsigned long sbnr, unsigned long ebnr,
 781                enum update_sync_bits_mode mode)
 782{
 783        /*
 784         * We keep a count of set bits per resync-extent in the ->rs_left
 785         * caching member, so we need to loop and work within the resync extent
 786         * alignment. Typically this loop will execute exactly once.
 787         */
 788        unsigned long flags;
 789        unsigned long count = 0;
 790        unsigned int cleared = 0;
 791        while (sbnr <= ebnr) {
 792                /* set temporary boundary bit number to last bit number within
 793                 * the resync extent of the current start bit number,
 794                 * but cap at provided end bit number */
 795                unsigned long tbnr = min(ebnr, sbnr | BM_BLOCKS_PER_BM_EXT_MASK);
 796                unsigned long c;
 797
 798                if (mode == RECORD_RS_FAILED)
 799                        /* Only called from drbd_rs_failed_io(), bits
 800                         * supposedly still set.  Recount, maybe some
 801                         * of the bits have been successfully cleared
 802                         * by application IO meanwhile.
 803                         */
 804                        c = drbd_bm_count_bits(device, sbnr, tbnr);
 805                else if (mode == SET_IN_SYNC)
 806                        c = drbd_bm_clear_bits(device, sbnr, tbnr);
 807                else /* if (mode == SET_OUT_OF_SYNC) */
 808                        c = drbd_bm_set_bits(device, sbnr, tbnr);
 809
 810                if (c) {
 811                        spin_lock_irqsave(&device->al_lock, flags);
 812                        cleared += update_rs_extent(device, BM_BIT_TO_EXT(sbnr), c, mode);
 813                        spin_unlock_irqrestore(&device->al_lock, flags);
 814                        count += c;
 815                }
 816                sbnr = tbnr + 1;
 817        }
 818        if (count) {
 819                if (mode == SET_IN_SYNC) {
 820                        unsigned long still_to_go = drbd_bm_total_weight(device);
 821                        bool rs_is_done = (still_to_go <= device->rs_failed);
 822                        drbd_advance_rs_marks(device, still_to_go);
 823                        if (cleared || rs_is_done)
 824                                maybe_schedule_on_disk_bitmap_update(device, rs_is_done);
 825                } else if (mode == RECORD_RS_FAILED)
 826                        device->rs_failed += count;
 827                wake_up(&device->al_wait);
 828        }
 829        return count;
 830}
 831
 832static bool plausible_request_size(int size)
 833{
 834        return size > 0
 835                && size <= DRBD_MAX_BATCH_BIO_SIZE
 836                && IS_ALIGNED(size, 512);
 837}
 838
 839/* clear the bit corresponding to the piece of storage in question:
 840 * size byte of data starting from sector.  Only clear a bits of the affected
 841 * one ore more _aligned_ BM_BLOCK_SIZE blocks.
 842 *
 843 * called by worker on C_SYNC_TARGET and receiver on SyncSource.
 844 *
 845 */
 846int __drbd_change_sync(struct drbd_device *device, sector_t sector, int size,
 847                enum update_sync_bits_mode mode)
 848{
 849        /* Is called from worker and receiver context _only_ */
 850        unsigned long sbnr, ebnr, lbnr;
 851        unsigned long count = 0;
 852        sector_t esector, nr_sectors;
 853
 854        /* This would be an empty REQ_PREFLUSH, be silent. */
 855        if ((mode == SET_OUT_OF_SYNC) && size == 0)
 856                return 0;
 857
 858        if (!plausible_request_size(size)) {
 859                drbd_err(device, "%s: sector=%llus size=%d nonsense!\n",
 860                                drbd_change_sync_fname[mode],
 861                                (unsigned long long)sector, size);
 862                return 0;
 863        }
 864
 865        if (!get_ldev(device))
 866                return 0; /* no disk, no metadata, no bitmap to manipulate bits in */
 867
 868        nr_sectors = get_capacity(device->vdisk);
 869        esector = sector + (size >> 9) - 1;
 870
 871        if (!expect(sector < nr_sectors))
 872                goto out;
 873        if (!expect(esector < nr_sectors))
 874                esector = nr_sectors - 1;
 875
 876        lbnr = BM_SECT_TO_BIT(nr_sectors-1);
 877
 878        if (mode == SET_IN_SYNC) {
 879                /* Round up start sector, round down end sector.  We make sure
 880                 * we only clear full, aligned, BM_BLOCK_SIZE blocks. */
 881                if (unlikely(esector < BM_SECT_PER_BIT-1))
 882                        goto out;
 883                if (unlikely(esector == (nr_sectors-1)))
 884                        ebnr = lbnr;
 885                else
 886                        ebnr = BM_SECT_TO_BIT(esector - (BM_SECT_PER_BIT-1));
 887                sbnr = BM_SECT_TO_BIT(sector + BM_SECT_PER_BIT-1);
 888        } else {
 889                /* We set it out of sync, or record resync failure.
 890                 * Should not round anything here. */
 891                sbnr = BM_SECT_TO_BIT(sector);
 892                ebnr = BM_SECT_TO_BIT(esector);
 893        }
 894
 895        count = update_sync_bits(device, sbnr, ebnr, mode);
 896out:
 897        put_ldev(device);
 898        return count;
 899}
 900
 901static
 902struct bm_extent *_bme_get(struct drbd_device *device, unsigned int enr)
 903{
 904        struct lc_element *e;
 905        struct bm_extent *bm_ext;
 906        int wakeup = 0;
 907        unsigned long rs_flags;
 908
 909        spin_lock_irq(&device->al_lock);
 910        if (device->resync_locked > device->resync->nr_elements/2) {
 911                spin_unlock_irq(&device->al_lock);
 912                return NULL;
 913        }
 914        e = lc_get(device->resync, enr);
 915        bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
 916        if (bm_ext) {
 917                if (bm_ext->lce.lc_number != enr) {
 918                        bm_ext->rs_left = drbd_bm_e_weight(device, enr);
 919                        bm_ext->rs_failed = 0;
 920                        lc_committed(device->resync);
 921                        wakeup = 1;
 922                }
 923                if (bm_ext->lce.refcnt == 1)
 924                        device->resync_locked++;
 925                set_bit(BME_NO_WRITES, &bm_ext->flags);
 926        }
 927        rs_flags = device->resync->flags;
 928        spin_unlock_irq(&device->al_lock);
 929        if (wakeup)
 930                wake_up(&device->al_wait);
 931
 932        if (!bm_ext) {
 933                if (rs_flags & LC_STARVING)
 934                        drbd_warn(device, "Have to wait for element"
 935                             " (resync LRU too small?)\n");
 936                BUG_ON(rs_flags & LC_LOCKED);
 937        }
 938
 939        return bm_ext;
 940}
 941
 942static int _is_in_al(struct drbd_device *device, unsigned int enr)
 943{
 944        int rv;
 945
 946        spin_lock_irq(&device->al_lock);
 947        rv = lc_is_used(device->act_log, enr);
 948        spin_unlock_irq(&device->al_lock);
 949
 950        return rv;
 951}
 952
 953/**
 954 * drbd_rs_begin_io() - Gets an extent in the resync LRU cache and sets it to BME_LOCKED
 955 * @device:     DRBD device.
 956 * @sector:     The sector number.
 957 *
 958 * This functions sleeps on al_wait. Returns 0 on success, -EINTR if interrupted.
 959 */
 960int drbd_rs_begin_io(struct drbd_device *device, sector_t sector)
 961{
 962        unsigned int enr = BM_SECT_TO_EXT(sector);
 963        struct bm_extent *bm_ext;
 964        int i, sig;
 965        bool sa;
 966
 967retry:
 968        sig = wait_event_interruptible(device->al_wait,
 969                        (bm_ext = _bme_get(device, enr)));
 970        if (sig)
 971                return -EINTR;
 972
 973        if (test_bit(BME_LOCKED, &bm_ext->flags))
 974                return 0;
 975
 976        /* step aside only while we are above c-min-rate; unless disabled. */
 977        sa = drbd_rs_c_min_rate_throttle(device);
 978
 979        for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
 980                sig = wait_event_interruptible(device->al_wait,
 981                                               !_is_in_al(device, enr * AL_EXT_PER_BM_SECT + i) ||
 982                                               (sa && test_bit(BME_PRIORITY, &bm_ext->flags)));
 983
 984                if (sig || (sa && test_bit(BME_PRIORITY, &bm_ext->flags))) {
 985                        spin_lock_irq(&device->al_lock);
 986                        if (lc_put(device->resync, &bm_ext->lce) == 0) {
 987                                bm_ext->flags = 0; /* clears BME_NO_WRITES and eventually BME_PRIORITY */
 988                                device->resync_locked--;
 989                                wake_up(&device->al_wait);
 990                        }
 991                        spin_unlock_irq(&device->al_lock);
 992                        if (sig)
 993                                return -EINTR;
 994                        if (schedule_timeout_interruptible(HZ/10))
 995                                return -EINTR;
 996                        goto retry;
 997                }
 998        }
 999        set_bit(BME_LOCKED, &bm_ext->flags);
1000        return 0;
1001}
1002
1003/**
1004 * drbd_try_rs_begin_io() - Gets an extent in the resync LRU cache, does not sleep
1005 * @device:     DRBD device.
1006 * @sector:     The sector number.
1007 *
1008 * Gets an extent in the resync LRU cache, sets it to BME_NO_WRITES, then
1009 * tries to set it to BME_LOCKED. Returns 0 upon success, and -EAGAIN
1010 * if there is still application IO going on in this area.
1011 */
1012int drbd_try_rs_begin_io(struct drbd_device *device, sector_t sector)
1013{
1014        unsigned int enr = BM_SECT_TO_EXT(sector);
1015        const unsigned int al_enr = enr*AL_EXT_PER_BM_SECT;
1016        struct lc_element *e;
1017        struct bm_extent *bm_ext;
1018        int i;
1019        bool throttle = drbd_rs_should_slow_down(device, sector, true);
1020
1021        /* If we need to throttle, a half-locked (only marked BME_NO_WRITES,
1022         * not yet BME_LOCKED) extent needs to be kicked out explicitly if we
1023         * need to throttle. There is at most one such half-locked extent,
1024         * which is remembered in resync_wenr. */
1025
1026        if (throttle && device->resync_wenr != enr)
1027                return -EAGAIN;
1028
1029        spin_lock_irq(&device->al_lock);
1030        if (device->resync_wenr != LC_FREE && device->resync_wenr != enr) {
1031                /* in case you have very heavy scattered io, it may
1032                 * stall the syncer undefined if we give up the ref count
1033                 * when we try again and requeue.
1034                 *
1035                 * if we don't give up the refcount, but the next time
1036                 * we are scheduled this extent has been "synced" by new
1037                 * application writes, we'd miss the lc_put on the
1038                 * extent we keep the refcount on.
1039                 * so we remembered which extent we had to try again, and
1040                 * if the next requested one is something else, we do
1041                 * the lc_put here...
1042                 * we also have to wake_up
1043                 */
1044                e = lc_find(device->resync, device->resync_wenr);
1045                bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1046                if (bm_ext) {
1047                        D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1048                        D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1049                        clear_bit(BME_NO_WRITES, &bm_ext->flags);
1050                        device->resync_wenr = LC_FREE;
1051                        if (lc_put(device->resync, &bm_ext->lce) == 0) {
1052                                bm_ext->flags = 0;
1053                                device->resync_locked--;
1054                        }
1055                        wake_up(&device->al_wait);
1056                } else {
1057                        drbd_alert(device, "LOGIC BUG\n");
1058                }
1059        }
1060        /* TRY. */
1061        e = lc_try_get(device->resync, enr);
1062        bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1063        if (bm_ext) {
1064                if (test_bit(BME_LOCKED, &bm_ext->flags))
1065                        goto proceed;
1066                if (!test_and_set_bit(BME_NO_WRITES, &bm_ext->flags)) {
1067                        device->resync_locked++;
1068                } else {
1069                        /* we did set the BME_NO_WRITES,
1070                         * but then could not set BME_LOCKED,
1071                         * so we tried again.
1072                         * drop the extra reference. */
1073                        bm_ext->lce.refcnt--;
1074                        D_ASSERT(device, bm_ext->lce.refcnt > 0);
1075                }
1076                goto check_al;
1077        } else {
1078                /* do we rather want to try later? */
1079                if (device->resync_locked > device->resync->nr_elements-3)
1080                        goto try_again;
1081                /* Do or do not. There is no try. -- Yoda */
1082                e = lc_get(device->resync, enr);
1083                bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1084                if (!bm_ext) {
1085                        const unsigned long rs_flags = device->resync->flags;
1086                        if (rs_flags & LC_STARVING)
1087                                drbd_warn(device, "Have to wait for element"
1088                                     " (resync LRU too small?)\n");
1089                        BUG_ON(rs_flags & LC_LOCKED);
1090                        goto try_again;
1091                }
1092                if (bm_ext->lce.lc_number != enr) {
1093                        bm_ext->rs_left = drbd_bm_e_weight(device, enr);
1094                        bm_ext->rs_failed = 0;
1095                        lc_committed(device->resync);
1096                        wake_up(&device->al_wait);
1097                        D_ASSERT(device, test_bit(BME_LOCKED, &bm_ext->flags) == 0);
1098                }
1099                set_bit(BME_NO_WRITES, &bm_ext->flags);
1100                D_ASSERT(device, bm_ext->lce.refcnt == 1);
1101                device->resync_locked++;
1102                goto check_al;
1103        }
1104check_al:
1105        for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
1106                if (lc_is_used(device->act_log, al_enr+i))
1107                        goto try_again;
1108        }
1109        set_bit(BME_LOCKED, &bm_ext->flags);
1110proceed:
1111        device->resync_wenr = LC_FREE;
1112        spin_unlock_irq(&device->al_lock);
1113        return 0;
1114
1115try_again:
1116        if (bm_ext) {
1117                if (throttle) {
1118                        D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1119                        D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1120                        clear_bit(BME_NO_WRITES, &bm_ext->flags);
1121                        device->resync_wenr = LC_FREE;
1122                        if (lc_put(device->resync, &bm_ext->lce) == 0) {
1123                                bm_ext->flags = 0;
1124                                device->resync_locked--;
1125                        }
1126                        wake_up(&device->al_wait);
1127                } else
1128                        device->resync_wenr = enr;
1129        }
1130        spin_unlock_irq(&device->al_lock);
1131        return -EAGAIN;
1132}
1133
1134void drbd_rs_complete_io(struct drbd_device *device, sector_t sector)
1135{
1136        unsigned int enr = BM_SECT_TO_EXT(sector);
1137        struct lc_element *e;
1138        struct bm_extent *bm_ext;
1139        unsigned long flags;
1140
1141        spin_lock_irqsave(&device->al_lock, flags);
1142        e = lc_find(device->resync, enr);
1143        bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1144        if (!bm_ext) {
1145                spin_unlock_irqrestore(&device->al_lock, flags);
1146                if (__ratelimit(&drbd_ratelimit_state))
1147                        drbd_err(device, "drbd_rs_complete_io() called, but extent not found\n");
1148                return;
1149        }
1150
1151        if (bm_ext->lce.refcnt == 0) {
1152                spin_unlock_irqrestore(&device->al_lock, flags);
1153                drbd_err(device, "drbd_rs_complete_io(,%llu [=%u]) called, "
1154                    "but refcnt is 0!?\n",
1155                    (unsigned long long)sector, enr);
1156                return;
1157        }
1158
1159        if (lc_put(device->resync, &bm_ext->lce) == 0) {
1160                bm_ext->flags = 0; /* clear BME_LOCKED, BME_NO_WRITES and BME_PRIORITY */
1161                device->resync_locked--;
1162                wake_up(&device->al_wait);
1163        }
1164
1165        spin_unlock_irqrestore(&device->al_lock, flags);
1166}
1167
1168/**
1169 * drbd_rs_cancel_all() - Removes all extents from the resync LRU (even BME_LOCKED)
1170 * @device:     DRBD device.
1171 */
1172void drbd_rs_cancel_all(struct drbd_device *device)
1173{
1174        spin_lock_irq(&device->al_lock);
1175
1176        if (get_ldev_if_state(device, D_FAILED)) { /* Makes sure ->resync is there. */
1177                lc_reset(device->resync);
1178                put_ldev(device);
1179        }
1180        device->resync_locked = 0;
1181        device->resync_wenr = LC_FREE;
1182        spin_unlock_irq(&device->al_lock);
1183        wake_up(&device->al_wait);
1184}
1185
1186/**
1187 * drbd_rs_del_all() - Gracefully remove all extents from the resync LRU
1188 * @device:     DRBD device.
1189 *
1190 * Returns 0 upon success, -EAGAIN if at least one reference count was
1191 * not zero.
1192 */
1193int drbd_rs_del_all(struct drbd_device *device)
1194{
1195        struct lc_element *e;
1196        struct bm_extent *bm_ext;
1197        int i;
1198
1199        spin_lock_irq(&device->al_lock);
1200
1201        if (get_ldev_if_state(device, D_FAILED)) {
1202                /* ok, ->resync is there. */
1203                for (i = 0; i < device->resync->nr_elements; i++) {
1204                        e = lc_element_by_index(device->resync, i);
1205                        bm_ext = lc_entry(e, struct bm_extent, lce);
1206                        if (bm_ext->lce.lc_number == LC_FREE)
1207                                continue;
1208                        if (bm_ext->lce.lc_number == device->resync_wenr) {
1209                                drbd_info(device, "dropping %u in drbd_rs_del_all, apparently"
1210                                     " got 'synced' by application io\n",
1211                                     device->resync_wenr);
1212                                D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1213                                D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1214                                clear_bit(BME_NO_WRITES, &bm_ext->flags);
1215                                device->resync_wenr = LC_FREE;
1216                                lc_put(device->resync, &bm_ext->lce);
1217                        }
1218                        if (bm_ext->lce.refcnt != 0) {
1219                                drbd_info(device, "Retrying drbd_rs_del_all() later. "
1220                                     "refcnt=%d\n", bm_ext->lce.refcnt);
1221                                put_ldev(device);
1222                                spin_unlock_irq(&device->al_lock);
1223                                return -EAGAIN;
1224                        }
1225                        D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1226                        D_ASSERT(device, !test_bit(BME_NO_WRITES, &bm_ext->flags));
1227                        lc_del(device->resync, &bm_ext->lce);
1228                }
1229                D_ASSERT(device, device->resync->used == 0);
1230                put_ldev(device);
1231        }
1232        spin_unlock_irq(&device->al_lock);
1233        wake_up(&device->al_wait);
1234
1235        return 0;
1236}
1237