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/drbd.h>
  28 #include "drbd_int.h"
  29 #include "drbd_wrappers.h"
  30
  31 /* We maintain a trivial check sum in our on disk activity log.
  32  * With that we can ensure correct operation even when the storage
  33  * device might do a partial (last) sector write while loosing power.
  34  */
  35 struct __packed al_transaction {
  36         u32       magic;
  37         u32       tr_number;
  38         struct __packed {
  39                 u32 pos;
  40                 u32 extent; } updates[1 + AL_EXTENTS_PT];
  41         u32       xor_sum;
  42 };
  43
  44 struct update_odbm_work {
  45         struct drbd_work w;
  46         unsigned int enr;
  47 };
  48
  49 struct update_al_work {
  50         struct drbd_work w;
  51         struct lc_element *al_ext;
  52         struct completion event;
  53         unsigned int enr;
  54         /* if old_enr != LC_FREE, write corresponding bitmap sector, too */
  55         unsigned int old_enr;
  56 };
  57
  58 struct drbd_atodb_wait {
  59         atomic_t           count;
  60         struct completion  io_done;
  61         struct drbd_conf   *mdev;
  62         int                error;
  63 };
  64
  65
  66 int w_al_write_transaction(struct drbd_conf *, struct drbd_work *, int);
  67
  68 static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
  69                                  struct drbd_backing_dev *bdev,
  70                                  struct page *page, sector_t sector,
  71                                  int rw, int size)
  72 {
  73         struct bio *bio;
  74         struct drbd_md_io md_io;
  75         int ok;
  76
  77         md_io.mdev = mdev;
  78         init_completion(&md_io.event);
  79         md_io.error = 0;
  80
  81         if ((rw & WRITE) && !test_bit(MD_NO_FUA, &mdev->flags))
  82                 rw |= REQ_FUA;
  83         rw |= REQ_SYNC;
  84
  85         bio = bio_alloc(GFP_NOIO, 1);
  86         bio->bi_bdev = bdev->md_bdev;
  87         bio->bi_sector = sector;
  88         ok = (bio_add_page(bio, page, size, 0) == size);
  89         if (!ok)
  90                 goto out;
  91         bio->bi_private = &md_io;
  92         bio->bi_end_io = drbd_md_io_complete;
  93         bio->bi_rw = rw;
  94
  95         if (FAULT_ACTIVE(mdev, (rw & WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))
  96                 bio_endio(bio, -EIO);
  97         else
  98                 submit_bio(rw, bio);
  99         wait_for_completion(&md_io.event);
 100         ok = bio_flagged(bio, BIO_UPTODATE) && md_io.error == 0;
 101
 102  out:
 103         bio_put(bio);
 104         return ok;
 105 }
 106
 107 int drbd_md_sync_page_io(struct drbd_conf *mdev, struct drbd_backing_dev *bdev,
 108                          sector_t sector, int rw)
 109 {
 110         int logical_block_size, mask, ok;
 111         int offset = 0;
 112         struct page *iop = mdev->md_io_page;
 113
 114         D_ASSERT(mutex_is_locked(&mdev->md_io_mutex));
 115
 116         BUG_ON(!bdev->md_bdev);
 117
 118         logical_block_size = bdev_logical_block_size(bdev->md_bdev);
 119         if (logical_block_size == 0)
 120                 logical_block_size = MD_SECTOR_SIZE;
 121
 122         /* in case logical_block_size != 512 [ s390 only? ] */
 123         if (logical_block_size != MD_SECTOR_SIZE) {
 124                 mask = (logical_block_size / MD_SECTOR_SIZE) - 1;
 125                 D_ASSERT(mask == 1 || mask == 3 || mask == 7);
 126                 D_ASSERT(logical_block_size == (mask+1) * MD_SECTOR_SIZE);
 127                 offset = sector & mask;
 128                 sector = sector & ~mask;
 129                 iop = mdev->md_io_tmpp;
 130
 131                 if (rw & WRITE) {
 132                         /* these are GFP_KERNEL pages, pre-allocated
 133                          * on device initialization */
 134                         void *p = page_address(mdev->md_io_page);
 135                         void *hp = page_address(mdev->md_io_tmpp);
 136
 137                         ok = _drbd_md_sync_page_io(mdev, bdev, iop, sector,
 138                                         READ, logical_block_size);
 139
 140                         if (unlikely(!ok)) {
 141                                 dev_err(DEV, "drbd_md_sync_page_io(,%llus,"
 142                                     "READ [logical_block_size!=512]) failed!\n",
 143                                     (unsigned long long)sector);
 144                                 return 0;
 145                         }
 146
 147                         memcpy(hp + offset*MD_SECTOR_SIZE, p, MD_SECTOR_SIZE);
 148                 }
 149         }
 150
 151         if (sector < drbd_md_first_sector(bdev) ||
 152             sector > drbd_md_last_sector(bdev))
 153                 dev_alert(DEV, "%s [%d]:%s(,%llus,%s) out of range md access!\n",
 154                      current->comm, current->pid, __func__,
 155                      (unsigned long long)sector, (rw & WRITE) ? "WRITE" : "READ");
 156
 157         ok = _drbd_md_sync_page_io(mdev, bdev, iop, sector, rw, logical_block_size);
 158         if (unlikely(!ok)) {
 159                 dev_err(DEV, "drbd_md_sync_page_io(,%llus,%s) failed!\n",
 160                     (unsigned long long)sector, (rw & WRITE) ? "WRITE" : "READ");
 161                 return 0;
 162         }
 163
 164         if (logical_block_size != MD_SECTOR_SIZE && !(rw & WRITE)) {
 165                 void *p = page_address(mdev->md_io_page);
 166                 void *hp = page_address(mdev->md_io_tmpp);
 167
 168                 memcpy(p, hp + offset*MD_SECTOR_SIZE, MD_SECTOR_SIZE);
 169         }
 170
 171         return ok;
 172 }
 173
 174 static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr)
 175 {
 176         struct lc_element *al_ext;
 177         struct lc_element *tmp;
 178         unsigned long     al_flags = 0;
 179
 180         spin_lock_irq(&mdev->al_lock);
 181         tmp = lc_find(mdev->resync, enr/AL_EXT_PER_BM_SECT);
 182         if (unlikely(tmp != NULL)) {
 183                 struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
 184                 if (test_bit(BME_NO_WRITES, &bm_ext->flags)) {
 185                         spin_unlock_irq(&mdev->al_lock);
 186                         return NULL;
 187                 }
 188         }
 189         al_ext   = lc_get(mdev->act_log, enr);
 190         al_flags = mdev->act_log->flags;
 191         spin_unlock_irq(&mdev->al_lock);
 192
 193         /*
 194         if (!al_ext) {
 195                 if (al_flags & LC_STARVING)
 196                         dev_warn(DEV, "Have to wait for LRU element (AL too small?)\n");
 197                 if (al_flags & LC_DIRTY)
 198                         dev_warn(DEV, "Ongoing AL update (AL device too slow?)\n");
 199         }
 200         */
 201
 202         return al_ext;
 203 }
 204
 205 void drbd_al_begin_io(struct drbd_conf *mdev, sector_t sector)
 206 {
 207         unsigned int enr = (sector >> (AL_EXTENT_SHIFT-9));
 208         struct lc_element *al_ext;
 209         struct update_al_work al_work;
 210
 211         D_ASSERT(atomic_read(&mdev->local_cnt) > 0);
 212
 213         wait_event(mdev->al_wait, (al_ext = _al_get(mdev, enr)));
 214
 215         if (al_ext->lc_number != enr) {
 216                 /* drbd_al_write_transaction(mdev,al_ext,enr);
 217                  * recurses into generic_make_request(), which
 218                  * disallows recursion, bios being serialized on the
 219                  * current->bio_tail list now.
 220                  * we have to delegate updates to the activity log
 221                  * to the worker thread. */
 222                 init_completion(&al_work.event);
 223                 al_work.al_ext = al_ext;
 224                 al_work.enr = enr;
 225                 al_work.old_enr = al_ext->lc_number;
 226                 al_work.w.cb = w_al_write_transaction;
 227                 drbd_queue_work_front(&mdev->data.work, &al_work.w);
 228                 wait_for_completion(&al_work.event);
 229
 230                 mdev->al_writ_cnt++;
 231
 232                 spin_lock_irq(&mdev->al_lock);
 233                 lc_changed(mdev->act_log, al_ext);
 234                 spin_unlock_irq(&mdev->al_lock);
 235                 wake_up(&mdev->al_wait);
 236         }
 237 }
 238
 239 void drbd_al_complete_io(struct drbd_conf *mdev, sector_t sector)
 240 {
 241         unsigned int enr = (sector >> (AL_EXTENT_SHIFT-9));
 242         struct lc_element *extent;
 243         unsigned long flags;
 244
 245         spin_lock_irqsave(&mdev->al_lock, flags);
 246
 247         extent = lc_find(mdev->act_log, enr);
 248
 249         if (!extent) {
 250                 spin_unlock_irqrestore(&mdev->al_lock, flags);
 251                 dev_err(DEV, "al_complete_io() called on inactive extent %u\n", enr);
 252                 return;
 253         }
 254
 255         if (lc_put(mdev->act_log, extent) == 0)
 256                 wake_up(&mdev->al_wait);
 257
 258         spin_unlock_irqrestore(&mdev->al_lock, flags);
 259 }
 260
 261 int
 262 w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
 263 {
 264         struct update_al_work *aw = container_of(w, struct update_al_work, w);
 265         struct lc_element *updated = aw->al_ext;
 266         const unsigned int new_enr = aw->enr;
 267         const unsigned int evicted = aw->old_enr;
 268         struct al_transaction *buffer;
 269         sector_t sector;
 270         int i, n, mx;
 271         unsigned int extent_nr;
 272         u32 xor_sum = 0;
 273
 274         if (!get_ldev(mdev)) {
 275                 dev_err(DEV,
 276                         "disk is %s, cannot start al transaction (-%d +%d)\n",
 277                         drbd_disk_str(mdev->state.disk), evicted, new_enr);
 278                 complete(&((struct update_al_work *)w)->event);
 279                 return 1;
 280         }
 281         /* do we have to do a bitmap write, first?
 282          * TODO reduce maximum latency:
 283          * submit both bios, then wait for both,
 284          * instead of doing two synchronous sector writes.
 285          * For now, we must not write the transaction,
 286          * if we cannot write out the bitmap of the evicted extent. */
 287         if (mdev->state.conn < C_CONNECTED && evicted != LC_FREE)
 288                 drbd_bm_write_sect(mdev, evicted/AL_EXT_PER_BM_SECT);
 289
 290         /* The bitmap write may have failed, causing a state change. */
 291         if (mdev->state.disk < D_INCONSISTENT) {
 292                 dev_err(DEV,
 293                         "disk is %s, cannot write al transaction (-%d +%d)\n",
 294                         drbd_disk_str(mdev->state.disk), evicted, new_enr);
 295                 complete(&((struct update_al_work *)w)->event);
 296                 put_ldev(mdev);
 297                 return 1;
 298         }
 299
 300         mutex_lock(&mdev->md_io_mutex); /* protects md_io_buffer, al_tr_cycle, ... */
 301         buffer = (struct al_transaction *)page_address(mdev->md_io_page);
 302
 303         buffer->magic = __constant_cpu_to_be32(DRBD_MAGIC);
 304         buffer->tr_number = cpu_to_be32(mdev->al_tr_number);
 305
 306         n = lc_index_of(mdev->act_log, updated);
 307
 308         buffer->updates[0].pos = cpu_to_be32(n);
 309         buffer->updates[0].extent = cpu_to_be32(new_enr);
 310
 311         xor_sum ^= new_enr;
 312
 313         mx = min_t(int, AL_EXTENTS_PT,
 314                    mdev->act_log->nr_elements - mdev->al_tr_cycle);
 315         for (i = 0; i < mx; i++) {
 316                 unsigned idx = mdev->al_tr_cycle + i;
 317                 extent_nr = lc_element_by_index(mdev->act_log, idx)->lc_number;
 318                 buffer->updates[i+1].pos = cpu_to_be32(idx);
 319                 buffer->updates[i+1].extent = cpu_to_be32(extent_nr);
 320                 xor_sum ^= extent_nr;
 321         }
 322         for (; i < AL_EXTENTS_PT; i++) {
 323                 buffer->updates[i+1].pos = __constant_cpu_to_be32(-1);
 324                 buffer->updates[i+1].extent = __constant_cpu_to_be32(LC_FREE);
 325                 xor_sum ^= LC_FREE;
 326         }
 327         mdev->al_tr_cycle += AL_EXTENTS_PT;
 328         if (mdev->al_tr_cycle >= mdev->act_log->nr_elements)
 329                 mdev->al_tr_cycle = 0;
 330
 331         buffer->xor_sum = cpu_to_be32(xor_sum);
 332
 333         sector =  mdev->ldev->md.md_offset
 334                 + mdev->ldev->md.al_offset + mdev->al_tr_pos;
 335
 336         if (!drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE))
 337                 drbd_chk_io_error(mdev, 1, TRUE);
 338
 339         if (++mdev->al_tr_pos >
 340             div_ceil(mdev->act_log->nr_elements, AL_EXTENTS_PT))
 341                 mdev->al_tr_pos = 0;
 342
 343         D_ASSERT(mdev->al_tr_pos < MD_AL_MAX_SIZE);
 344         mdev->al_tr_number++;
 345
 346         mutex_unlock(&mdev->md_io_mutex);
 347
 348         complete(&((struct update_al_work *)w)->event);
 349         put_ldev(mdev);
 350
 351         return 1;
 352 }
 353
 354 /**
 355  * drbd_al_read_tr() - Read a single transaction from the on disk activity log
 356  * @mdev:       DRBD device.
 357  * @bdev:       Block device to read form.
 358  * @b:          pointer to an al_transaction.
 359  * @index:      On disk slot of the transaction to read.
 360  *
 361  * Returns -1 on IO error, 0 on checksum error and 1 upon success.
 362  */
 363 static int drbd_al_read_tr(struct drbd_conf *mdev,
 364                            struct drbd_backing_dev *bdev,
 365                            struct al_transaction *b,
 366                            int index)
 367 {
 368         sector_t sector;
 369         int rv, i;
 370         u32 xor_sum = 0;
 371
 372         sector = bdev->md.md_offset + bdev->md.al_offset + index;
 373
 374         /* Dont process error normally,
 375          * as this is done before disk is attached! */
 376         if (!drbd_md_sync_page_io(mdev, bdev, sector, READ))
 377                 return -1;
 378
 379         rv = (be32_to_cpu(b->magic) == DRBD_MAGIC);
 380
 381         for (i = 0; i < AL_EXTENTS_PT + 1; i++)
 382                 xor_sum ^= be32_to_cpu(b->updates[i].extent);
 383         rv &= (xor_sum == be32_to_cpu(b->xor_sum));
 384
 385         return rv;
 386 }
 387
 388 /**
 389  * drbd_al_read_log() - Restores the activity log from its on disk representation.
 390  * @mdev:       DRBD device.
 391  * @bdev:       Block device to read form.
 392  *
 393  * Returns 1 on success, returns 0 when reading the log failed due to IO errors.
 394  */
 395 int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 396 {
 397         struct al_transaction *buffer;
 398         int i;
 399         int rv;
 400         int mx;
 401         int active_extents = 0;
 402         int transactions = 0;
 403         int found_valid = 0;
 404         int from = 0;
 405         int to = 0;
 406         u32 from_tnr = 0;
 407         u32 to_tnr = 0;
 408         u32 cnr;
 409
 410         mx = div_ceil(mdev->act_log->nr_elements, AL_EXTENTS_PT);
 411
 412         /* lock out all other meta data io for now,
 413          * and make sure the page is mapped.
 414          */
 415         mutex_lock(&mdev->md_io_mutex);
 416         buffer = page_address(mdev->md_io_page);
 417
 418         /* Find the valid transaction in the log */
 419         for (i = 0; i <= mx; i++) {
 420                 rv = drbd_al_read_tr(mdev, bdev, buffer, i);
 421                 if (rv == 0)
 422                         continue;
 423                 if (rv == -1) {
 424                         mutex_unlock(&mdev->md_io_mutex);
 425                         return 0;
 426                 }
 427                 cnr = be32_to_cpu(buffer->tr_number);
 428
 429                 if (++found_valid == 1) {
 430                         from = i;
 431                         to = i;
 432                         from_tnr = cnr;
 433                         to_tnr = cnr;
 434                         continue;
 435                 }
 436                 if ((int)cnr - (int)from_tnr < 0) {
 437                         D_ASSERT(from_tnr - cnr + i - from == mx+1);
 438                         from = i;
 439                         from_tnr = cnr;
 440                 }
 441                 if ((int)cnr - (int)to_tnr > 0) {
 442                         D_ASSERT(cnr - to_tnr == i - to);
 443                         to = i;
 444                         to_tnr = cnr;
 445                 }
 446         }
 447
 448         if (!found_valid) {
 449                 dev_warn(DEV, "No usable activity log found.\n");
 450                 mutex_unlock(&mdev->md_io_mutex);
 451                 return 1;
 452         }
 453
 454         /* Read the valid transactions.
 455          * dev_info(DEV, "Reading from %d to %d.\n",from,to); */
 456         i = from;
 457         while (1) {
 458                 int j, pos;
 459                 unsigned int extent_nr;
 460                 unsigned int trn;
 461
 462                 rv = drbd_al_read_tr(mdev, bdev, buffer, i);
 463                 ERR_IF(rv == 0) goto cancel;
 464                 if (rv == -1) {
 465                         mutex_unlock(&mdev->md_io_mutex);
 466                         return 0;
 467                 }
 468
 469                 trn = be32_to_cpu(buffer->tr_number);
 470
 471                 spin_lock_irq(&mdev->al_lock);
 472
 473                 /* This loop runs backwards because in the cyclic
 474                    elements there might be an old version of the
 475                    updated element (in slot 0). So the element in slot 0
 476                    can overwrite old versions. */
 477                 for (j = AL_EXTENTS_PT; j >= 0; j--) {
 478                         pos = be32_to_cpu(buffer->updates[j].pos);
 479                         extent_nr = be32_to_cpu(buffer->updates[j].extent);
 480
 481                         if (extent_nr == LC_FREE)
 482                                 continue;
 483
 484                         lc_set(mdev->act_log, extent_nr, pos);
 485                         active_extents++;
 486                 }
 487                 spin_unlock_irq(&mdev->al_lock);
 488
 489                 transactions++;
 490
 491 cancel:
 492                 if (i == to)
 493                         break;
 494                 i++;
 495                 if (i > mx)
 496                         i = 0;
 497         }
 498
 499         mdev->al_tr_number = to_tnr+1;
 500         mdev->al_tr_pos = to;
 501         if (++mdev->al_tr_pos >
 502             div_ceil(mdev->act_log->nr_elements, AL_EXTENTS_PT))
 503                 mdev->al_tr_pos = 0;
 504
 505         /* ok, we are done with it */
 506         mutex_unlock(&mdev->md_io_mutex);
 507
 508         dev_info(DEV, "Found %d transactions (%d active extents) in activity log.\n",
 509              transactions, active_extents);
 510
 511         return 1;
 512 }
 513
 514 static void atodb_endio(struct bio *bio, int error)
 515 {
 516         struct drbd_atodb_wait *wc = bio->bi_private;
 517         struct drbd_conf *mdev = wc->mdev;
 518         struct page *page;
 519         int uptodate = bio_flagged(bio, BIO_UPTODATE);
 520
 521         /* strange behavior of some lower level drivers...
 522          * fail the request by clearing the uptodate flag,
 523          * but do not return any error?! */
 524         if (!error && !uptodate)
 525                 error = -EIO;
 526
 527         drbd_chk_io_error(mdev, error, TRUE);
 528         if (error && wc->error == 0)
 529                 wc->error = error;
 530
 531         if (atomic_dec_and_test(&wc->count))
 532                 complete(&wc->io_done);
 533
 534         page = bio->bi_io_vec[0].bv_page;
 535         put_page(page);
 536         bio_put(bio);
 537         mdev->bm_writ_cnt++;
 538         put_ldev(mdev);
 539 }
 540
 541 /* sector to word */
 542 #define S2W(s)  ((s)<<(BM_EXT_SHIFT-BM_BLOCK_SHIFT-LN2_BPL))
 543
 544 /* activity log to on disk bitmap -- prepare bio unless that sector
 545  * is already covered by previously prepared bios */
 546 static int atodb_prepare_unless_covered(struct drbd_conf *mdev,
 547                                         struct bio **bios,
 548                                         unsigned int enr,
 549                                         struct drbd_atodb_wait *wc) __must_hold(local)
 550 {
 551         struct bio *bio;
 552         struct page *page;
 553         sector_t on_disk_sector;
 554         unsigned int page_offset = PAGE_SIZE;
 555         int offset;
 556         int i = 0;
 557         int err = -ENOMEM;
 558
 559         /* We always write aligned, full 4k blocks,
 560          * so we can ignore the logical_block_size (for now) */
 561         enr &= ~7U;
 562         on_disk_sector = enr + mdev->ldev->md.md_offset
 563                              + mdev->ldev->md.bm_offset;
 564
 565         D_ASSERT(!(on_disk_sector & 7U));
 566
 567         /* Check if that enr is already covered by an already created bio.
 568          * Caution, bios[] is not NULL terminated,
 569          * but only initialized to all NULL.
 570          * For completely scattered activity log,
 571          * the last invocation iterates over all bios,
 572          * and finds the last NULL entry.
 573          */
 574         while ((bio = bios[i])) {
 575                 if (bio->bi_sector == on_disk_sector)
 576                         return 0;
 577                 i++;
 578         }
 579         /* bios[i] == NULL, the next not yet used slot */
 580
 581         /* GFP_KERNEL, we are not in the write-out path */
 582         bio = bio_alloc(GFP_KERNEL, 1);
 583         if (bio == NULL)
 584                 return -ENOMEM;
 585
 586         if (i > 0) {
 587                 const struct bio_vec *prev_bv = bios[i-1]->bi_io_vec;
 588                 page_offset = prev_bv->bv_offset + prev_bv->bv_len;
 589                 page = prev_bv->bv_page;
 590         }
 591         if (page_offset == PAGE_SIZE) {
 592                 page = alloc_page(__GFP_HIGHMEM);
 593                 if (page == NULL)
 594                         goto out_bio_put;
 595                 page_offset = 0;
 596         } else {
 597                 get_page(page);
 598         }
 599
 600         offset = S2W(enr);
 601         drbd_bm_get_lel(mdev, offset,
 602                         min_t(size_t, S2W(8), drbd_bm_words(mdev) - offset),
 603                         kmap(page) + page_offset);
 604         kunmap(page);
 605
 606         bio->bi_private = wc;
 607         bio->bi_end_io = atodb_endio;
 608         bio->bi_bdev = mdev->ldev->md_bdev;
 609         bio->bi_sector = on_disk_sector;
 610
 611         if (bio_add_page(bio, page, 4096, page_offset) != 4096)
 612                 goto out_put_page;
 613
 614         atomic_inc(&wc->count);
 615         /* we already know that we may do this...
 616          * get_ldev_if_state(mdev,D_ATTACHING);
 617          * just get the extra reference, so that the local_cnt reflects
 618          * the number of pending IO requests DRBD at its backing device.
 619          */
 620         atomic_inc(&mdev->local_cnt);
 621
 622         bios[i] = bio;
 623
 624         return 0;
 625
 626 out_put_page:
 627         err = -EINVAL;
 628         put_page(page);
 629 out_bio_put:
 630         bio_put(bio);
 631         return err;
 632 }
 633
 634 /**
 635  * drbd_al_to_on_disk_bm() -  * Writes bitmap parts covered by active AL extents
 636  * @mdev:       DRBD device.
 637  *
 638  * Called when we detach (unconfigure) local storage,
 639  * or when we go from R_PRIMARY to R_SECONDARY role.
 640  */
 641 void drbd_al_to_on_disk_bm(struct drbd_conf *mdev)
 642 {
 643         int i, nr_elements;
 644         unsigned int enr;
 645         struct bio **bios;
 646         struct drbd_atodb_wait wc;
 647
 648         ERR_IF (!get_ldev_if_state(mdev, D_ATTACHING))
 649                 return; /* sorry, I don't have any act_log etc... */
 650
 651         wait_event(mdev->al_wait, lc_try_lock(mdev->act_log));
 652
 653         nr_elements = mdev->act_log->nr_elements;
 654
 655         /* GFP_KERNEL, we are not in anyone's write-out path */
 656         bios = kzalloc(sizeof(struct bio *) * nr_elements, GFP_KERNEL);
 657         if (!bios)
 658                 goto submit_one_by_one;
 659
 660         atomic_set(&wc.count, 0);
 661         init_completion(&wc.io_done);
 662         wc.mdev = mdev;
 663         wc.error = 0;
 664
 665         for (i = 0; i < nr_elements; i++) {
 666                 enr = lc_element_by_index(mdev->act_log, i)->lc_number;
 667                 if (enr == LC_FREE)
 668                         continue;
 669                 /* next statement also does atomic_inc wc.count and local_cnt */
 670                 if (atodb_prepare_unless_covered(mdev, bios,
 671                                                 enr/AL_EXT_PER_BM_SECT,
 672                                                 &wc))
 673                         goto free_bios_submit_one_by_one;
 674         }
 675
 676         /* unnecessary optimization? */
 677         lc_unlock(mdev->act_log);
 678         wake_up(&mdev->al_wait);
 679
 680         /* all prepared, submit them */
 681         for (i = 0; i < nr_elements; i++) {
 682                 if (bios[i] == NULL)
 683                         break;
 684                 if (FAULT_ACTIVE(mdev, DRBD_FAULT_MD_WR)) {
 685                         bios[i]->bi_rw = WRITE;
 686                         bio_endio(bios[i], -EIO);
 687                 } else {
 688                         submit_bio(WRITE, bios[i]);
 689                 }
 690         }
 691
 692         /* always (try to) flush bitmap to stable storage */
 693         drbd_md_flush(mdev);
 694
 695         /* In case we did not submit a single IO do not wait for
 696          * them to complete. ( Because we would wait forever here. )
 697          *
 698          * In case we had IOs and they are already complete, there
 699          * is not point in waiting anyways.
 700          * Therefore this if () ... */
 701         if (atomic_read(&wc.count))
 702                 wait_for_completion(&wc.io_done);
 703
 704         put_ldev(mdev);
 705
 706         kfree(bios);
 707         return;
 708
 709  free_bios_submit_one_by_one:
 710         /* free everything by calling the endio callback directly. */
 711         for (i = 0; i < nr_elements && bios[i]; i++)
 712                 bio_endio(bios[i], 0);
 713
 714         kfree(bios);
 715
 716  submit_one_by_one:
 717         dev_warn(DEV, "Using the slow drbd_al_to_on_disk_bm()\n");
 718
 719         for (i = 0; i < mdev->act_log->nr_elements; i++) {
 720                 enr = lc_element_by_index(mdev->act_log, i)->lc_number;
 721                 if (enr == LC_FREE)
 722                         continue;
 723                 /* Really slow: if we have al-extents 16..19 active,
 724                  * sector 4 will be written four times! Synchronous! */
 725                 drbd_bm_write_sect(mdev, enr/AL_EXT_PER_BM_SECT);
 726         }
 727
 728         lc_unlock(mdev->act_log);
 729         wake_up(&mdev->al_wait);
 730         put_ldev(mdev);
 731 }
 732
 733 /**
 734  * drbd_al_apply_to_bm() - Sets the bitmap to diry(1) where covered ba active AL extents
 735  * @mdev:       DRBD device.
 736  */
 737 void drbd_al_apply_to_bm(struct drbd_conf *mdev)
 738 {
 739         unsigned int enr;
 740         unsigned long add = 0;
 741         char ppb[10];
 742         int i, tmp;
 743
 744         wait_event(mdev->al_wait, lc_try_lock(mdev->act_log));
 745
 746         for (i = 0; i < mdev->act_log->nr_elements; i++) {
 747                 enr = lc_element_by_index(mdev->act_log, i)->lc_number;
 748                 if (enr == LC_FREE)
 749                         continue;
 750                 tmp = drbd_bm_ALe_set_all(mdev, enr);
 751                 dynamic_dev_dbg(DEV, "AL: set %d bits in extent %u\n", tmp, enr);
 752                 add += tmp;
 753         }
 754
 755         lc_unlock(mdev->act_log);
 756         wake_up(&mdev->al_wait);
 757
 758         dev_info(DEV, "Marked additional %s as out-of-sync based on AL.\n",
 759              ppsize(ppb, Bit2KB(add)));
 760 }
 761
 762 static int _try_lc_del(struct drbd_conf *mdev, struct lc_element *al_ext)
 763 {
 764         int rv;
 765
 766         spin_lock_irq(&mdev->al_lock);
 767         rv = (al_ext->refcnt == 0);
 768         if (likely(rv))
 769                 lc_del(mdev->act_log, al_ext);
 770         spin_unlock_irq(&mdev->al_lock);
 771
 772         return rv;
 773 }
 774
 775 /**
 776  * drbd_al_shrink() - Removes all active extents form the activity log
 777  * @mdev:       DRBD device.
 778  *
 779  * Removes all active extents form the activity log, waiting until
 780  * the reference count of each entry dropped to 0 first, of course.
 781  *
 782  * You need to lock mdev->act_log with lc_try_lock() / lc_unlock()
 783  */
 784 void drbd_al_shrink(struct drbd_conf *mdev)
 785 {
 786         struct lc_element *al_ext;
 787         int i;
 788
 789         D_ASSERT(test_bit(__LC_DIRTY, &mdev->act_log->flags));
 790
 791         for (i = 0; i < mdev->act_log->nr_elements; i++) {
 792                 al_ext = lc_element_by_index(mdev->act_log, i);
 793                 if (al_ext->lc_number == LC_FREE)
 794                         continue;
 795                 wait_event(mdev->al_wait, _try_lc_del(mdev, al_ext));
 796         }
 797
 798         wake_up(&mdev->al_wait);
 799 }
 800
 801 static int w_update_odbm(struct drbd_conf *mdev, struct drbd_work *w, int unused)
 802 {
 803         struct update_odbm_work *udw = container_of(w, struct update_odbm_work, w);
 804
 805         if (!get_ldev(mdev)) {
 806                 if (__ratelimit(&drbd_ratelimit_state))
 807                         dev_warn(DEV, "Can not update on disk bitmap, local IO disabled.\n");
 808                 kfree(udw);
 809                 return 1;
 810         }
 811
 812         drbd_bm_write_sect(mdev, udw->enr);
 813         put_ldev(mdev);
 814
 815         kfree(udw);
 816
 817         if (drbd_bm_total_weight(mdev) <= mdev->rs_failed) {
 818                 switch (mdev->state.conn) {
 819                 case C_SYNC_SOURCE:  case C_SYNC_TARGET:
 820                 case C_PAUSED_SYNC_S: case C_PAUSED_SYNC_T:
 821                         drbd_resync_finished(mdev);
 822                 default:
 823                         /* nothing to do */
 824                         break;
 825                 }
 826         }
 827         drbd_bcast_sync_progress(mdev);
 828
 829         return 1;
 830 }
 831
 832
 833 /* ATTENTION. The AL's extents are 4MB each, while the extents in the
 834  * resync LRU-cache are 16MB each.
 835  * The caller of this function has to hold an get_ldev() reference.
 836  *
 837  * TODO will be obsoleted once we have a caching lru of the on disk bitmap
 838  */
 839 static void drbd_try_clear_on_disk_bm(struct drbd_conf *mdev, sector_t sector,
 840                                       int count, int success)
 841 {
 842         struct lc_element *e;
 843         struct update_odbm_work *udw;
 844
 845         unsigned int enr;
 846
 847         D_ASSERT(atomic_read(&mdev->local_cnt));
 848
 849         /* I simply assume that a sector/size pair never crosses
 850          * a 16 MB extent border. (Currently this is true...) */
 851         enr = BM_SECT_TO_EXT(sector);
 852
 853         e = lc_get(mdev->resync, enr);
 854         if (e) {
 855                 struct bm_extent *ext = lc_entry(e, struct bm_extent, lce);
 856                 if (ext->lce.lc_number == enr) {
 857                         if (success)
 858                                 ext->rs_left -= count;
 859                         else
 860                                 ext->rs_failed += count;
 861                         if (ext->rs_left < ext->rs_failed) {
 862                                 dev_err(DEV, "BAD! sector=%llus enr=%u rs_left=%d "
 863                                     "rs_failed=%d count=%d\n",
 864                                      (unsigned long long)sector,
 865                                      ext->lce.lc_number, ext->rs_left,
 866                                      ext->rs_failed, count);
 867                                 dump_stack();
 868
 869                                 lc_put(mdev->resync, &ext->lce);
 870                                 drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
 871                                 return;
 872                         }
 873                 } else {
 874                         /* Normally this element should be in the cache,
 875                          * since drbd_rs_begin_io() pulled it already in.
 876                          *
 877                          * But maybe an application write finished, and we set
 878                          * something outside the resync lru_cache in sync.
 879                          */
 880                         int rs_left = drbd_bm_e_weight(mdev, enr);
 881                         if (ext->flags != 0) {
 882                                 dev_warn(DEV, "changing resync lce: %d[%u;%02lx]"
 883                                      " -> %d[%u;00]\n",
 884                                      ext->lce.lc_number, ext->rs_left,
 885                                      ext->flags, enr, rs_left);
 886                                 ext->flags = 0;
 887                         }
 888                         if (ext->rs_failed) {
 889                                 dev_warn(DEV, "Kicking resync_lru element enr=%u "
 890                                      "out with rs_failed=%d\n",
 891                                      ext->lce.lc_number, ext->rs_failed);
 892                                 set_bit(WRITE_BM_AFTER_RESYNC, &mdev->flags);
 893                         }
 894                         ext->rs_left = rs_left;
 895                         ext->rs_failed = success ? 0 : count;
 896                         lc_changed(mdev->resync, &ext->lce);
 897                 }
 898                 lc_put(mdev->resync, &ext->lce);
 899                 /* no race, we are within the al_lock! */
 900
 901                 if (ext->rs_left == ext->rs_failed) {
 902                         ext->rs_failed = 0;
 903
 904                         udw = kmalloc(sizeof(*udw), GFP_ATOMIC);
 905                         if (udw) {
 906                                 udw->enr = ext->lce.lc_number;
 907                                 udw->w.cb = w_update_odbm;
 908                                 drbd_queue_work_front(&mdev->data.work, &udw->w);
 909                         } else {
 910                                 dev_warn(DEV, "Could not kmalloc an udw\n");
 911                                 set_bit(WRITE_BM_AFTER_RESYNC, &mdev->flags);
 912                         }
 913                 }
 914         } else {
 915                 dev_err(DEV, "lc_get() failed! locked=%d/%d flags=%lu\n",
 916                     mdev->resync_locked,
 917                     mdev->resync->nr_elements,
 918                     mdev->resync->flags);
 919         }
 920 }
 921
 922 /* clear the bit corresponding to the piece of storage in question:
 923  * size byte of data starting from sector.  Only clear a bits of the affected
 924  * one ore more _aligned_ BM_BLOCK_SIZE blocks.
 925  *
 926  * called by worker on C_SYNC_TARGET and receiver on SyncSource.
 927  *
 928  */
 929 void __drbd_set_in_sync(struct drbd_conf *mdev, sector_t sector, int size,
 930                        const char *file, const unsigned int line)
 931 {
 932         /* Is called from worker and receiver context _only_ */
 933         unsigned long sbnr, ebnr, lbnr;
 934         unsigned long count = 0;
 935         sector_t esector, nr_sectors;
 936         int wake_up = 0;
 937         unsigned long flags;
 938
 939         if (size <= 0 || (size & 0x1ff) != 0 || size > DRBD_MAX_SEGMENT_SIZE) {
 940                 dev_err(DEV, "drbd_set_in_sync: sector=%llus size=%d nonsense!\n",
 941                                 (unsigned long long)sector, size);
 942                 return;
 943         }
 944         nr_sectors = drbd_get_capacity(mdev->this_bdev);
 945         esector = sector + (size >> 9) - 1;
 946
 947         ERR_IF(sector >= nr_sectors) return;
 948         ERR_IF(esector >= nr_sectors) esector = (nr_sectors-1);
 949
 950         lbnr = BM_SECT_TO_BIT(nr_sectors-1);
 951
 952         /* we clear it (in sync).
 953          * round up start sector, round down end sector.  we make sure we only
 954          * clear full, aligned, BM_BLOCK_SIZE (4K) blocks */
 955         if (unlikely(esector < BM_SECT_PER_BIT-1))
 956                 return;
 957         if (unlikely(esector == (nr_sectors-1)))
 958                 ebnr = lbnr;
 959         else
 960                 ebnr = BM_SECT_TO_BIT(esector - (BM_SECT_PER_BIT-1));
 961         sbnr = BM_SECT_TO_BIT(sector + BM_SECT_PER_BIT-1);
 962
 963         if (sbnr > ebnr)
 964                 return;
 965
 966         /*
 967          * ok, (capacity & 7) != 0 sometimes, but who cares...
 968          * we count rs_{total,left} in bits, not sectors.
 969          */
 970         count = drbd_bm_clear_bits(mdev, sbnr, ebnr);
 971         if (count && get_ldev(mdev)) {
 972                 unsigned long now = jiffies;
 973                 unsigned long last = mdev->rs_mark_time[mdev->rs_last_mark];
 974                 int next = (mdev->rs_last_mark + 1) % DRBD_SYNC_MARKS;
 975                 if (time_after_eq(now, last + DRBD_SYNC_MARK_STEP)) {
 976                         unsigned long tw = drbd_bm_total_weight(mdev);
 977                         if (mdev->rs_mark_left[mdev->rs_last_mark] != tw &&
 978                             mdev->state.conn != C_PAUSED_SYNC_T &&
 979                             mdev->state.conn != C_PAUSED_SYNC_S) {
 980                                 mdev->rs_mark_time[next] = now;
 981                                 mdev->rs_mark_left[next] = tw;
 982                                 mdev->rs_last_mark = next;
 983                         }
 984                 }
 985                 spin_lock_irqsave(&mdev->al_lock, flags);
 986                 drbd_try_clear_on_disk_bm(mdev, sector, count, TRUE);
 987                 spin_unlock_irqrestore(&mdev->al_lock, flags);
 988
 989                 /* just wake_up unconditional now, various lc_chaged(),
 990                  * lc_put() in drbd_try_clear_on_disk_bm(). */
 991                 wake_up = 1;
 992                 put_ldev(mdev);
 993         }
 994         if (wake_up)
 995                 wake_up(&mdev->al_wait);
 996 }
 997
 998 /*
 999  * this is intended to set one request worth of data out of sync.
1000  * affects at least 1 bit,
1001  * and at most 1+DRBD_MAX_SEGMENT_SIZE/BM_BLOCK_SIZE bits.
1002  *
1003  * called by tl_clear and drbd_send_dblock (==drbd_make_request).
1004  * so this can be _any_ process.
1005  */
1006 void __drbd_set_out_of_sync(struct drbd_conf *mdev, sector_t sector, int size,
1007                             const char *file, const unsigned int line)
1008 {
1009         unsigned long sbnr, ebnr, lbnr, flags;
1010         sector_t esector, nr_sectors;
1011         unsigned int enr, count;
1012         struct lc_element *e;
1013
1014         if (size <= 0 || (size & 0x1ff) != 0 || size > DRBD_MAX_SEGMENT_SIZE) {
1015                 dev_err(DEV, "sector: %llus, size: %d\n",
1016                         (unsigned long long)sector, size);
1017                 return;
1018         }
1019
1020         if (!get_ldev(mdev))
1021                 return; /* no disk, no metadata, no bitmap to set bits in */
1022
1023         nr_sectors = drbd_get_capacity(mdev->this_bdev);
1024         esector = sector + (size >> 9) - 1;
1025
1026         ERR_IF(sector >= nr_sectors)
1027                 goto out;
1028         ERR_IF(esector >= nr_sectors)
1029                 esector = (nr_sectors-1);
1030
1031         lbnr = BM_SECT_TO_BIT(nr_sectors-1);
1032
1033         /* we set it out of sync,
1034          * we do not need to round anything here */
1035         sbnr = BM_SECT_TO_BIT(sector);
1036         ebnr = BM_SECT_TO_BIT(esector);
1037
1038         /* ok, (capacity & 7) != 0 sometimes, but who cares...
1039          * we count rs_{total,left} in bits, not sectors.  */
1040         spin_lock_irqsave(&mdev->al_lock, flags);
1041         count = drbd_bm_set_bits(mdev, sbnr, ebnr);
1042
1043         enr = BM_SECT_TO_EXT(sector);
1044         e = lc_find(mdev->resync, enr);
1045         if (e)
1046                 lc_entry(e, struct bm_extent, lce)->rs_left += count;
1047         spin_unlock_irqrestore(&mdev->al_lock, flags);
1048
1049 out:
1050         put_ldev(mdev);
1051 }
1052
1053 static
1054 struct bm_extent *_bme_get(struct drbd_conf *mdev, unsigned int enr)
1055 {
1056         struct lc_element *e;
1057         struct bm_extent *bm_ext;
1058         int wakeup = 0;
1059         unsigned long rs_flags;
1060
1061         spin_lock_irq(&mdev->al_lock);
1062         if (mdev->resync_locked > mdev->resync->nr_elements/2) {
1063                 spin_unlock_irq(&mdev->al_lock);
1064                 return NULL;
1065         }
1066         e = lc_get(mdev->resync, enr);
1067         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1068         if (bm_ext) {
1069                 if (bm_ext->lce.lc_number != enr) {
1070                         bm_ext->rs_left = drbd_bm_e_weight(mdev, enr);
1071                         bm_ext->rs_failed = 0;
1072                         lc_changed(mdev->resync, &bm_ext->lce);
1073                         wakeup = 1;
1074                 }
1075                 if (bm_ext->lce.refcnt == 1)
1076                         mdev->resync_locked++;
1077                 set_bit(BME_NO_WRITES, &bm_ext->flags);
1078         }
1079         rs_flags = mdev->resync->flags;
1080         spin_unlock_irq(&mdev->al_lock);
1081         if (wakeup)
1082                 wake_up(&mdev->al_wait);
1083
1084         if (!bm_ext) {
1085                 if (rs_flags & LC_STARVING)
1086                         dev_warn(DEV, "Have to wait for element"
1087                              " (resync LRU too small?)\n");
1088                 BUG_ON(rs_flags & LC_DIRTY);
1089         }
1090
1091         return bm_ext;
1092 }
1093
1094 static int _is_in_al(struct drbd_conf *mdev, unsigned int enr)
1095 {
1096         struct lc_element *al_ext;
1097         int rv = 0;
1098
1099         spin_lock_irq(&mdev->al_lock);
1100         if (unlikely(enr == mdev->act_log->new_number))
1101                 rv = 1;
1102         else {
1103                 al_ext = lc_find(mdev->act_log, enr);
1104                 if (al_ext) {
1105                         if (al_ext->refcnt)
1106                                 rv = 1;
1107                 }
1108         }
1109         spin_unlock_irq(&mdev->al_lock);
1110
1111         /*
1112         if (unlikely(rv)) {
1113                 dev_info(DEV, "Delaying sync read until app's write is done\n");
1114         }
1115         */
1116         return rv;
1117 }
1118
1119 /**
1120  * drbd_rs_begin_io() - Gets an extent in the resync LRU cache and sets it to BME_LOCKED
1121  * @mdev:       DRBD device.
1122  * @sector:     The sector number.
1123  *
1124  * This functions sleeps on al_wait. Returns 0 on success, -EINTR if interrupted.
1125  */
1126 int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector)
1127 {
1128         unsigned int enr = BM_SECT_TO_EXT(sector);
1129         struct bm_extent *bm_ext;
1130         int i, sig;
1131
1132         sig = wait_event_interruptible(mdev->al_wait,
1133                         (bm_ext = _bme_get(mdev, enr)));
1134         if (sig)
1135                 return -EINTR;
1136
1137         if (test_bit(BME_LOCKED, &bm_ext->flags))
1138                 return 0;
1139
1140         for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
1141                 sig = wait_event_interruptible(mdev->al_wait,
1142                                 !_is_in_al(mdev, enr * AL_EXT_PER_BM_SECT + i));
1143                 if (sig) {
1144                         spin_lock_irq(&mdev->al_lock);
1145                         if (lc_put(mdev->resync, &bm_ext->lce) == 0) {
1146                                 clear_bit(BME_NO_WRITES, &bm_ext->flags);
1147                                 mdev->resync_locked--;
1148                                 wake_up(&mdev->al_wait);
1149                         }
1150                         spin_unlock_irq(&mdev->al_lock);
1151                         return -EINTR;
1152                 }
1153         }
1154         set_bit(BME_LOCKED, &bm_ext->flags);
1155         return 0;
1156 }
1157
1158 /**
1159  * drbd_try_rs_begin_io() - Gets an extent in the resync LRU cache, does not sleep
1160  * @mdev:       DRBD device.
1161  * @sector:     The sector number.
1162  *
1163  * Gets an extent in the resync LRU cache, sets it to BME_NO_WRITES, then
1164  * tries to set it to BME_LOCKED. Returns 0 upon success, and -EAGAIN
1165  * if there is still application IO going on in this area.
1166  */
1167 int drbd_try_rs_begin_io(struct drbd_conf *mdev, sector_t sector)
1168 {
1169         unsigned int enr = BM_SECT_TO_EXT(sector);
1170         const unsigned int al_enr = enr*AL_EXT_PER_BM_SECT;
1171         struct lc_element *e;
1172         struct bm_extent *bm_ext;
1173         int i;
1174
1175         spin_lock_irq(&mdev->al_lock);
1176         if (mdev->resync_wenr != LC_FREE && mdev->resync_wenr != enr) {
1177                 /* in case you have very heavy scattered io, it may
1178                  * stall the syncer undefined if we give up the ref count
1179                  * when we try again and requeue.
1180                  *
1181                  * if we don't give up the refcount, but the next time
1182                  * we are scheduled this extent has been "synced" by new
1183                  * application writes, we'd miss the lc_put on the
1184                  * extent we keep the refcount on.
1185                  * so we remembered which extent we had to try again, and
1186                  * if the next requested one is something else, we do
1187                  * the lc_put here...
1188                  * we also have to wake_up
1189                  */
1190                 e = lc_find(mdev->resync, mdev->resync_wenr);
1191                 bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1192                 if (bm_ext) {
1193                         D_ASSERT(!test_bit(BME_LOCKED, &bm_ext->flags));
1194                         D_ASSERT(test_bit(BME_NO_WRITES, &bm_ext->flags));
1195                         clear_bit(BME_NO_WRITES, &bm_ext->flags);
1196                         mdev->resync_wenr = LC_FREE;
1197                         if (lc_put(mdev->resync, &bm_ext->lce) == 0)
1198                                 mdev->resync_locked--;
1199                         wake_up(&mdev->al_wait);
1200                 } else {
1201                         dev_alert(DEV, "LOGIC BUG\n");
1202                 }
1203         }
1204         /* TRY. */
1205         e = lc_try_get(mdev->resync, enr);
1206         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1207         if (bm_ext) {
1208                 if (test_bit(BME_LOCKED, &bm_ext->flags))
1209                         goto proceed;
1210                 if (!test_and_set_bit(BME_NO_WRITES, &bm_ext->flags)) {
1211                         mdev->resync_locked++;
1212                 } else {
1213                         /* we did set the BME_NO_WRITES,
1214                          * but then could not set BME_LOCKED,
1215                          * so we tried again.
1216                          * drop the extra reference. */
1217                         bm_ext->lce.refcnt--;
1218                         D_ASSERT(bm_ext->lce.refcnt > 0);
1219                 }
1220                 goto check_al;
1221         } else {
1222                 /* do we rather want to try later? */
1223                 if (mdev->resync_locked > mdev->resync->nr_elements-3)
1224                         goto try_again;
1225                 /* Do or do not. There is no try. -- Yoda */
1226                 e = lc_get(mdev->resync, enr);
1227                 bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1228                 if (!bm_ext) {
1229                         const unsigned long rs_flags = mdev->resync->flags;
1230                         if (rs_flags & LC_STARVING)
1231                                 dev_warn(DEV, "Have to wait for element"
1232                                      " (resync LRU too small?)\n");
1233                         BUG_ON(rs_flags & LC_DIRTY);
1234                         goto try_again;
1235                 }
1236                 if (bm_ext->lce.lc_number != enr) {
1237                         bm_ext->rs_left = drbd_bm_e_weight(mdev, enr);
1238                         bm_ext->rs_failed = 0;
1239                         lc_changed(mdev->resync, &bm_ext->lce);
1240                         wake_up(&mdev->al_wait);
1241                         D_ASSERT(test_bit(BME_LOCKED, &bm_ext->flags) == 0);
1242                 }
1243                 set_bit(BME_NO_WRITES, &bm_ext->flags);
1244                 D_ASSERT(bm_ext->lce.refcnt == 1);
1245                 mdev->resync_locked++;
1246                 goto check_al;
1247         }
1248 check_al:
1249         for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
1250                 if (unlikely(al_enr+i == mdev->act_log->new_number))
1251                         goto try_again;
1252                 if (lc_is_used(mdev->act_log, al_enr+i))
1253                         goto try_again;
1254         }
1255         set_bit(BME_LOCKED, &bm_ext->flags);
1256 proceed:
1257         mdev->resync_wenr = LC_FREE;
1258         spin_unlock_irq(&mdev->al_lock);
1259         return 0;
1260
1261 try_again:
1262         if (bm_ext)
1263                 mdev->resync_wenr = enr;
1264         spin_unlock_irq(&mdev->al_lock);
1265         return -EAGAIN;
1266 }
1267
1268 void drbd_rs_complete_io(struct drbd_conf *mdev, sector_t sector)
1269 {
1270         unsigned int enr = BM_SECT_TO_EXT(sector);
1271         struct lc_element *e;
1272         struct bm_extent *bm_ext;
1273         unsigned long flags;
1274
1275         spin_lock_irqsave(&mdev->al_lock, flags);
1276         e = lc_find(mdev->resync, enr);
1277         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1278         if (!bm_ext) {
1279                 spin_unlock_irqrestore(&mdev->al_lock, flags);
1280                 if (__ratelimit(&drbd_ratelimit_state))
1281                         dev_err(DEV, "drbd_rs_complete_io() called, but extent not found\n");
1282                 return;
1283         }
1284
1285         if (bm_ext->lce.refcnt == 0) {
1286                 spin_unlock_irqrestore(&mdev->al_lock, flags);
1287                 dev_err(DEV, "drbd_rs_complete_io(,%llu [=%u]) called, "
1288                     "but refcnt is 0!?\n",
1289                     (unsigned long long)sector, enr);
1290                 return;
1291         }
1292
1293         if (lc_put(mdev->resync, &bm_ext->lce) == 0) {
1294                 clear_bit(BME_LOCKED, &bm_ext->flags);
1295                 clear_bit(BME_NO_WRITES, &bm_ext->flags);
1296                 mdev->resync_locked--;
1297                 wake_up(&mdev->al_wait);
1298         }
1299
1300         spin_unlock_irqrestore(&mdev->al_lock, flags);
1301 }
1302
1303 /**
1304  * drbd_rs_cancel_all() - Removes all extents from the resync LRU (even BME_LOCKED)
1305  * @mdev:       DRBD device.
1306  */
1307 void drbd_rs_cancel_all(struct drbd_conf *mdev)
1308 {
1309         spin_lock_irq(&mdev->al_lock);
1310
1311         if (get_ldev_if_state(mdev, D_FAILED)) { /* Makes sure ->resync is there. */
1312                 lc_reset(mdev->resync);
1313                 put_ldev(mdev);
1314         }
1315         mdev->resync_locked = 0;
1316         mdev->resync_wenr = LC_FREE;
1317         spin_unlock_irq(&mdev->al_lock);
1318         wake_up(&mdev->al_wait);
1319 }
1320
1321 /**
1322  * drbd_rs_del_all() - Gracefully remove all extents from the resync LRU
1323  * @mdev:       DRBD device.
1324  *
1325  * Returns 0 upon success, -EAGAIN if at least one reference count was
1326  * not zero.
1327  */
1328 int drbd_rs_del_all(struct drbd_conf *mdev)
1329 {
1330         struct lc_element *e;
1331         struct bm_extent *bm_ext;
1332         int i;
1333
1334         spin_lock_irq(&mdev->al_lock);
1335
1336         if (get_ldev_if_state(mdev, D_FAILED)) {
1337                 /* ok, ->resync is there. */
1338                 for (i = 0; i < mdev->resync->nr_elements; i++) {
1339                         e = lc_element_by_index(mdev->resync, i);
1340                         bm_ext = lc_entry(e, struct bm_extent, lce);
1341                         if (bm_ext->lce.lc_number == LC_FREE)
1342                                 continue;
1343                         if (bm_ext->lce.lc_number == mdev->resync_wenr) {
1344                                 dev_info(DEV, "dropping %u in drbd_rs_del_all, apparently"
1345                                      " got 'synced' by application io\n",
1346                                      mdev->resync_wenr);
1347                                 D_ASSERT(!test_bit(BME_LOCKED, &bm_ext->flags));
1348                                 D_ASSERT(test_bit(BME_NO_WRITES, &bm_ext->flags));
1349                                 clear_bit(BME_NO_WRITES, &bm_ext->flags);
1350                                 mdev->resync_wenr = LC_FREE;
1351                                 lc_put(mdev->resync, &bm_ext->lce);
1352                         }
1353                         if (bm_ext->lce.refcnt != 0) {
1354                                 dev_info(DEV, "Retrying drbd_rs_del_all() later. "
1355                                      "refcnt=%d\n", bm_ext->lce.refcnt);
1356                                 put_ldev(mdev);
1357                                 spin_unlock_irq(&mdev->al_lock);
1358                                 return -EAGAIN;
1359                         }
1360                         D_ASSERT(!test_bit(BME_LOCKED, &bm_ext->flags));
1361                         D_ASSERT(!test_bit(BME_NO_WRITES, &bm_ext->flags));
1362                         lc_del(mdev->resync, &bm_ext->lce);
1363                 }
1364                 D_ASSERT(mdev->resync->used == 0);
1365                 put_ldev(mdev);
1366         }
1367         spin_unlock_irq(&mdev->al_lock);
1368
1369         return 0;
1370 }
1371
1372 /**
1373  * drbd_rs_failed_io() - Record information on a failure to resync the specified blocks
1374  * @mdev:       DRBD device.
1375  * @sector:     The sector number.
1376  * @size:       Size of failed IO operation, in byte.
1377  */
1378 void drbd_rs_failed_io(struct drbd_conf *mdev, sector_t sector, int size)
1379 {
1380         /* Is called from worker and receiver context _only_ */
1381         unsigned long sbnr, ebnr, lbnr;
1382         unsigned long count;
1383         sector_t esector, nr_sectors;
1384         int wake_up = 0;
1385
1386         if (size <= 0 || (size & 0x1ff) != 0 || size > DRBD_MAX_SEGMENT_SIZE) {
1387                 dev_err(DEV, "drbd_rs_failed_io: sector=%llus size=%d nonsense!\n",
1388                                 (unsigned long long)sector, size);
1389                 return;
1390         }
1391         nr_sectors = drbd_get_capacity(mdev->this_bdev);
1392         esector = sector + (size >> 9) - 1;
1393
1394         ERR_IF(sector >= nr_sectors) return;
1395         ERR_IF(esector >= nr_sectors) esector = (nr_sectors-1);
1396
1397         lbnr = BM_SECT_TO_BIT(nr_sectors-1);
1398
1399         /*
1400          * round up start sector, round down end sector.  we make sure we only
1401          * handle full, aligned, BM_BLOCK_SIZE (4K) blocks */
1402         if (unlikely(esector < BM_SECT_PER_BIT-1))
1403                 return;
1404         if (unlikely(esector == (nr_sectors-1)))
1405                 ebnr = lbnr;
1406         else
1407                 ebnr = BM_SECT_TO_BIT(esector - (BM_SECT_PER_BIT-1));
1408         sbnr = BM_SECT_TO_BIT(sector + BM_SECT_PER_BIT-1);
1409
1410         if (sbnr > ebnr)
1411                 return;
1412
1413         /*
1414          * ok, (capacity & 7) != 0 sometimes, but who cares...
1415          * we count rs_{total,left} in bits, not sectors.
1416          */
1417         spin_lock_irq(&mdev->al_lock);
1418         count = drbd_bm_count_bits(mdev, sbnr, ebnr);
1419         if (count) {
1420                 mdev->rs_failed += count;
1421
1422                 if (get_ldev(mdev)) {
1423                         drbd_try_clear_on_disk_bm(mdev, sector, count, FALSE);
1424                         put_ldev(mdev);
1425                 }
1426
1427                 /* just wake_up unconditional now, various lc_chaged(),
1428                  * lc_put() in drbd_try_clear_on_disk_bm(). */
1429                 wake_up = 1;
1430         }
1431         spin_unlock_irq(&mdev->al_lock);
1432         if (wake_up)
1433                 wake_up(&mdev->al_wait);
1434 }