dev-replace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STRATO AG 2012.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/bio.h>
   8 #include <linux/slab.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/kthread.h>
  11 #include <linux/math64.h>
  12 #include "misc.h"
  13 #include "ctree.h"
  14 #include "extent_map.h"
  15 #include "disk-io.h"
  16 #include "transaction.h"
  17 #include "print-tree.h"
  18 #include "volumes.h"
  19 #include "async-thread.h"
  20 #include "dev-replace.h"
  21 #include "sysfs.h"
  22 #include "zoned.h"
  23 #include "block-group.h"
  24 #include "fs.h"
  25 #include "accessors.h"
  26 #include "scrub.h"
  27
  28 /*
  29  * Device replace overview
  30  *
  31  * [Objective]
  32  * To copy all extents (both new and on-disk) from source device to target
  33  * device, while still keeping the filesystem read-write.
  34  *
  35  * [Method]
  36  * There are two main methods involved:
  37  *
  38  * - Write duplication
  39  *
  40  *   All new writes will be written to both target and source devices, so even
  41  *   if replace gets canceled, sources device still contains up-to-date data.
  42  *
  43  *   Location:          handle_ops_on_dev_replace() from btrfs_map_block()
  44  *   Start:             btrfs_dev_replace_start()
  45  *   End:               btrfs_dev_replace_finishing()
  46  *   Content:           Latest data/metadata
  47  *
  48  * - Copy existing extents
  49  *
  50  *   This happens by re-using scrub facility, as scrub also iterates through
  51  *   existing extents from commit root.
  52  *
  53  *   Location:          scrub_write_block_to_dev_replace() from
  54  *                      scrub_block_complete()
  55  *   Content:           Data/meta from commit root.
  56  *
  57  * Due to the content difference, we need to avoid nocow write when dev-replace
  58  * is happening.  This is done by marking the block group read-only and waiting
  59  * for NOCOW writes.
  60  *
  61  * After replace is done, the finishing part is done by swapping the target and
  62  * source devices.
  63  *
  64  *   Location:          btrfs_dev_replace_update_device_in_mapping_tree() from
  65  *                      btrfs_dev_replace_finishing()
  66  */
  67
  68 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
  69                                        int scrub_ret);
  70 static int btrfs_dev_replace_kthread(void *data);
  71
  72 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  73 {
  74         struct btrfs_dev_lookup_args args = { .devid = BTRFS_DEV_REPLACE_DEVID };
  75         struct btrfs_key key;
  76         struct btrfs_root *dev_root = fs_info->dev_root;
  77         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  78         struct extent_buffer *eb;
  79         int slot;
  80         int ret = 0;
  81         struct btrfs_path *path = NULL;
  82         int item_size;
  83         struct btrfs_dev_replace_item *ptr;
  84         u64 src_devid;
  85
  86         if (!dev_root)
  87                 return 0;
  88
  89         path = btrfs_alloc_path();
  90         if (!path) {
  91                 ret = -ENOMEM;
  92                 goto out;
  93         }
  94
  95         key.objectid = 0;
  96         key.type = BTRFS_DEV_REPLACE_KEY;
  97         key.offset = 0;
  98         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  99         if (ret) {
 100 no_valid_dev_replace_entry_found:
 101                 /*
 102                  * We don't have a replace item or it's corrupted.  If there is
 103                  * a replace target, fail the mount.
 104                  */
 105                 if (btrfs_find_device(fs_info->fs_devices, &args)) {
 106                         btrfs_err(fs_info,
 107                         "found replace target device without a valid replace item");
 108                         ret = -EUCLEAN;
 109                         goto out;
 110                 }
 111                 ret = 0;
 112                 dev_replace->replace_state =
 113                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 114                 dev_replace->cont_reading_from_srcdev_mode =
 115                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
 116                 dev_replace->time_started = 0;
 117                 dev_replace->time_stopped = 0;
 118                 atomic64_set(&dev_replace->num_write_errors, 0);
 119                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 120                 dev_replace->cursor_left = 0;
 121                 dev_replace->committed_cursor_left = 0;
 122                 dev_replace->cursor_left_last_write_of_item = 0;
 123                 dev_replace->cursor_right = 0;
 124                 dev_replace->srcdev = NULL;
 125                 dev_replace->tgtdev = NULL;
 126                 dev_replace->is_valid = 0;
 127                 dev_replace->item_needs_writeback = 0;
 128                 goto out;
 129         }
 130         slot = path->slots[0];
 131         eb = path->nodes[0];
 132         item_size = btrfs_item_size(eb, slot);
 133         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
 134
 135         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
 136                 btrfs_warn(fs_info,
 137                         "dev_replace entry found has unexpected size, ignore entry");
 138                 goto no_valid_dev_replace_entry_found;
 139         }
 140
 141         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
 142         dev_replace->cont_reading_from_srcdev_mode =
 143                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
 144         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
 145         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
 146         dev_replace->time_stopped =
 147                 btrfs_dev_replace_time_stopped(eb, ptr);
 148         atomic64_set(&dev_replace->num_write_errors,
 149                      btrfs_dev_replace_num_write_errors(eb, ptr));
 150         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 151                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 152         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 153         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 154         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 155         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 156         dev_replace->is_valid = 1;
 157
 158         dev_replace->item_needs_writeback = 0;
 159         switch (dev_replace->replace_state) {
 160         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 161         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 162         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 163                 /*
 164                  * We don't have an active replace item but if there is a
 165                  * replace target, fail the mount.
 166                  */
 167                 if (btrfs_find_device(fs_info->fs_devices, &args)) {
 168                         btrfs_err(fs_info,
 169 "replace without active item, run 'device scan --forget' on the target device");
 170                         ret = -EUCLEAN;
 171                 } else {
 172                         dev_replace->srcdev = NULL;
 173                         dev_replace->tgtdev = NULL;
 174                 }
 175                 break;
 176         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 177         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 178                 dev_replace->tgtdev = btrfs_find_device(fs_info->fs_devices, &args);
 179                 args.devid = src_devid;
 180                 dev_replace->srcdev = btrfs_find_device(fs_info->fs_devices, &args);
 181
 182                 /*
 183                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 184                  * missing
 185                  */
 186                 if (!dev_replace->srcdev &&
 187                     !btrfs_test_opt(fs_info, DEGRADED)) {
 188                         ret = -EIO;
 189                         btrfs_warn(fs_info,
 190                            "cannot mount because device replace operation is ongoing and");
 191                         btrfs_warn(fs_info,
 192                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 193                            src_devid);
 194                 }
 195                 if (!dev_replace->tgtdev &&
 196                     !btrfs_test_opt(fs_info, DEGRADED)) {
 197                         ret = -EIO;
 198                         btrfs_warn(fs_info,
 199                            "cannot mount because device replace operation is ongoing and");
 200                         btrfs_warn(fs_info,
 201                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 202                                 BTRFS_DEV_REPLACE_DEVID);
 203                 }
 204                 if (dev_replace->tgtdev) {
 205                         if (dev_replace->srcdev) {
 206                                 dev_replace->tgtdev->total_bytes =
 207                                         dev_replace->srcdev->total_bytes;
 208                                 dev_replace->tgtdev->disk_total_bytes =
 209                                         dev_replace->srcdev->disk_total_bytes;
 210                                 dev_replace->tgtdev->commit_total_bytes =
 211                                         dev_replace->srcdev->commit_total_bytes;
 212                                 dev_replace->tgtdev->bytes_used =
 213                                         dev_replace->srcdev->bytes_used;
 214                                 dev_replace->tgtdev->commit_bytes_used =
 215                                         dev_replace->srcdev->commit_bytes_used;
 216                         }
 217                         set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
 218                                 &dev_replace->tgtdev->dev_state);
 219
 220                         WARN_ON(fs_info->fs_devices->rw_devices == 0);
 221                         dev_replace->tgtdev->io_width = fs_info->sectorsize;
 222                         dev_replace->tgtdev->io_align = fs_info->sectorsize;
 223                         dev_replace->tgtdev->sector_size = fs_info->sectorsize;
 224                         dev_replace->tgtdev->fs_info = fs_info;
 225                         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
 226                                 &dev_replace->tgtdev->dev_state);
 227                 }
 228                 break;
 229         }
 230
 231 out:
 232         btrfs_free_path(path);
 233         return ret;
 234 }
 235
 236 /*
 237  * Initialize a new device for device replace target from a given source dev
 238  * and path.
 239  *
 240  * Return 0 and new device in @device_out, otherwise return < 0
 241  */
 242 static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 243                                   const char *device_path,
 244                                   struct btrfs_device *srcdev,
 245                                   struct btrfs_device **device_out)
 246 {
 247         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 248         struct btrfs_device *device;
 249         struct bdev_handle *bdev_handle;
 250         struct block_device *bdev;
 251         u64 devid = BTRFS_DEV_REPLACE_DEVID;
 252         int ret = 0;
 253
 254         *device_out = NULL;
 255         if (srcdev->fs_devices->seeding) {
 256                 btrfs_err(fs_info, "the filesystem is a seed filesystem!");
 257                 return -EINVAL;
 258         }
 259
 260         bdev_handle = bdev_open_by_path(device_path, BLK_OPEN_WRITE,
 261                                         fs_info->bdev_holder, NULL);
 262         if (IS_ERR(bdev_handle)) {
 263                 btrfs_err(fs_info, "target device %s is invalid!", device_path);
 264                 return PTR_ERR(bdev_handle);
 265         }
 266         bdev = bdev_handle->bdev;
 267
 268         if (!btrfs_check_device_zone_type(fs_info, bdev)) {
 269                 btrfs_err(fs_info,
 270                 "dev-replace: zoned type of target device mismatch with filesystem");
 271                 ret = -EINVAL;
 272                 goto error;
 273         }
 274
 275         sync_blockdev(bdev);
 276
 277         list_for_each_entry(device, &fs_devices->devices, dev_list) {
 278                 if (device->bdev == bdev) {
 279                         btrfs_err(fs_info,
 280                                   "target device is in the filesystem!");
 281                         ret = -EEXIST;
 282                         goto error;
 283                 }
 284         }
 285
 286
 287         if (bdev_nr_bytes(bdev) < btrfs_device_get_total_bytes(srcdev)) {
 288                 btrfs_err(fs_info,
 289                           "target device is smaller than source device!");
 290                 ret = -EINVAL;
 291                 goto error;
 292         }
 293
 294
 295         device = btrfs_alloc_device(NULL, &devid, NULL, device_path);
 296         if (IS_ERR(device)) {
 297                 ret = PTR_ERR(device);
 298                 goto error;
 299         }
 300
 301         ret = lookup_bdev(device_path, &device->devt);
 302         if (ret)
 303                 goto error;
 304
 305         set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
 306         device->generation = 0;
 307         device->io_width = fs_info->sectorsize;
 308         device->io_align = fs_info->sectorsize;
 309         device->sector_size = fs_info->sectorsize;
 310         device->total_bytes = btrfs_device_get_total_bytes(srcdev);
 311         device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
 312         device->bytes_used = btrfs_device_get_bytes_used(srcdev);
 313         device->commit_total_bytes = srcdev->commit_total_bytes;
 314         device->commit_bytes_used = device->bytes_used;
 315         device->fs_info = fs_info;
 316         device->bdev = bdev;
 317         device->bdev_handle = bdev_handle;
 318         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 319         set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 320         device->dev_stats_valid = 1;
 321         set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
 322         device->fs_devices = fs_devices;
 323
 324         ret = btrfs_get_dev_zone_info(device, false);
 325         if (ret)
 326                 goto error;
 327
 328         mutex_lock(&fs_devices->device_list_mutex);
 329         list_add(&device->dev_list, &fs_devices->devices);
 330         fs_devices->num_devices++;
 331         fs_devices->open_devices++;
 332         mutex_unlock(&fs_devices->device_list_mutex);
 333
 334         *device_out = device;
 335         return 0;
 336
 337 error:
 338         bdev_release(bdev_handle);
 339         return ret;
 340 }
 341
 342 /*
 343  * called from commit_transaction. Writes changed device replace state to
 344  * disk.
 345  */
 346 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans)
 347 {
 348         struct btrfs_fs_info *fs_info = trans->fs_info;
 349         int ret;
 350         struct btrfs_root *dev_root = fs_info->dev_root;
 351         struct btrfs_path *path;
 352         struct btrfs_key key;
 353         struct extent_buffer *eb;
 354         struct btrfs_dev_replace_item *ptr;
 355         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 356
 357         down_read(&dev_replace->rwsem);
 358         if (!dev_replace->is_valid ||
 359             !dev_replace->item_needs_writeback) {
 360                 up_read(&dev_replace->rwsem);
 361                 return 0;
 362         }
 363         up_read(&dev_replace->rwsem);
 364
 365         key.objectid = 0;
 366         key.type = BTRFS_DEV_REPLACE_KEY;
 367         key.offset = 0;
 368
 369         path = btrfs_alloc_path();
 370         if (!path) {
 371                 ret = -ENOMEM;
 372                 goto out;
 373         }
 374         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 375         if (ret < 0) {
 376                 btrfs_warn(fs_info,
 377                            "error %d while searching for dev_replace item!",
 378                            ret);
 379                 goto out;
 380         }
 381
 382         if (ret == 0 &&
 383             btrfs_item_size(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 384                 /*
 385                  * need to delete old one and insert a new one.
 386                  * Since no attempt is made to recover any old state, if the
 387                  * dev_replace state is 'running', the data on the target
 388                  * drive is lost.
 389                  * It would be possible to recover the state: just make sure
 390                  * that the beginning of the item is never changed and always
 391                  * contains all the essential information. Then read this
 392                  * minimal set of information and use it as a base for the
 393                  * new state.
 394                  */
 395                 ret = btrfs_del_item(trans, dev_root, path);
 396                 if (ret != 0) {
 397                         btrfs_warn(fs_info,
 398                                    "delete too small dev_replace item failed %d!",
 399                                    ret);
 400                         goto out;
 401                 }
 402                 ret = 1;
 403         }
 404
 405         if (ret == 1) {
 406                 /* need to insert a new item */
 407                 btrfs_release_path(path);
 408                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 409                                               &key, sizeof(*ptr));
 410                 if (ret < 0) {
 411                         btrfs_warn(fs_info,
 412                                    "insert dev_replace item failed %d!", ret);
 413                         goto out;
 414                 }
 415         }
 416
 417         eb = path->nodes[0];
 418         ptr = btrfs_item_ptr(eb, path->slots[0],
 419                              struct btrfs_dev_replace_item);
 420
 421         down_write(&dev_replace->rwsem);
 422         if (dev_replace->srcdev)
 423                 btrfs_set_dev_replace_src_devid(eb, ptr,
 424                         dev_replace->srcdev->devid);
 425         else
 426                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 427         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 428                 dev_replace->cont_reading_from_srcdev_mode);
 429         btrfs_set_dev_replace_replace_state(eb, ptr,
 430                 dev_replace->replace_state);
 431         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 432         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 433         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 434                 atomic64_read(&dev_replace->num_write_errors));
 435         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 436                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 437         dev_replace->cursor_left_last_write_of_item =
 438                 dev_replace->cursor_left;
 439         btrfs_set_dev_replace_cursor_left(eb, ptr,
 440                 dev_replace->cursor_left_last_write_of_item);
 441         btrfs_set_dev_replace_cursor_right(eb, ptr,
 442                 dev_replace->cursor_right);
 443         dev_replace->item_needs_writeback = 0;
 444         up_write(&dev_replace->rwsem);
 445
 446         btrfs_mark_buffer_dirty(trans, eb);
 447
 448 out:
 449         btrfs_free_path(path);
 450
 451         return ret;
 452 }
 453
 454 static int mark_block_group_to_copy(struct btrfs_fs_info *fs_info,
 455                                     struct btrfs_device *src_dev)
 456 {
 457         struct btrfs_path *path;
 458         struct btrfs_key key;
 459         struct btrfs_key found_key;
 460         struct btrfs_root *root = fs_info->dev_root;
 461         struct btrfs_dev_extent *dev_extent = NULL;
 462         struct btrfs_block_group *cache;
 463         struct btrfs_trans_handle *trans;
 464         int iter_ret = 0;
 465         int ret = 0;
 466         u64 chunk_offset;
 467
 468         /* Do not use "to_copy" on non zoned filesystem for now */
 469         if (!btrfs_is_zoned(fs_info))
 470                 return 0;
 471
 472         mutex_lock(&fs_info->chunk_mutex);
 473
 474         /* Ensure we don't have pending new block group */
 475         spin_lock(&fs_info->trans_lock);
 476         while (fs_info->running_transaction &&
 477                !list_empty(&fs_info->running_transaction->dev_update_list)) {
 478                 spin_unlock(&fs_info->trans_lock);
 479                 mutex_unlock(&fs_info->chunk_mutex);
 480                 trans = btrfs_attach_transaction(root);
 481                 if (IS_ERR(trans)) {
 482                         ret = PTR_ERR(trans);
 483                         mutex_lock(&fs_info->chunk_mutex);
 484                         if (ret == -ENOENT) {
 485                                 spin_lock(&fs_info->trans_lock);
 486                                 continue;
 487                         } else {
 488                                 goto unlock;
 489                         }
 490                 }
 491
 492                 ret = btrfs_commit_transaction(trans);
 493                 mutex_lock(&fs_info->chunk_mutex);
 494                 if (ret)
 495                         goto unlock;
 496
 497                 spin_lock(&fs_info->trans_lock);
 498         }
 499         spin_unlock(&fs_info->trans_lock);
 500
 501         path = btrfs_alloc_path();
 502         if (!path) {
 503                 ret = -ENOMEM;
 504                 goto unlock;
 505         }
 506
 507         path->reada = READA_FORWARD;
 508         path->search_commit_root = 1;
 509         path->skip_locking = 1;
 510
 511         key.objectid = src_dev->devid;
 512         key.type = BTRFS_DEV_EXTENT_KEY;
 513         key.offset = 0;
 514
 515         btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
 516                 struct extent_buffer *leaf = path->nodes[0];
 517
 518                 if (found_key.objectid != src_dev->devid)
 519                         break;
 520
 521                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
 522                         break;
 523
 524                 if (found_key.offset < key.offset)
 525                         break;
 526
 527                 dev_extent = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_extent);
 528
 529                 chunk_offset = btrfs_dev_extent_chunk_offset(leaf, dev_extent);
 530
 531                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
 532                 if (!cache)
 533                         continue;
 534
 535                 set_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
 536                 btrfs_put_block_group(cache);
 537         }
 538         if (iter_ret < 0)
 539                 ret = iter_ret;
 540
 541         btrfs_free_path(path);
 542 unlock:
 543         mutex_unlock(&fs_info->chunk_mutex);
 544
 545         return ret;
 546 }
 547
 548 bool btrfs_finish_block_group_to_copy(struct btrfs_device *srcdev,
 549                                       struct btrfs_block_group *cache,
 550                                       u64 physical)
 551 {
 552         struct btrfs_fs_info *fs_info = cache->fs_info;
 553         struct btrfs_chunk_map *map;
 554         u64 chunk_offset = cache->start;
 555         int num_extents, cur_extent;
 556         int i;
 557
 558         /* Do not use "to_copy" on non zoned filesystem for now */
 559         if (!btrfs_is_zoned(fs_info))
 560                 return true;
 561
 562         spin_lock(&cache->lock);
 563         if (test_bit(BLOCK_GROUP_FLAG_REMOVED, &cache->runtime_flags)) {
 564                 spin_unlock(&cache->lock);
 565                 return true;
 566         }
 567         spin_unlock(&cache->lock);
 568
 569         map = btrfs_get_chunk_map(fs_info, chunk_offset, 1);
 570         ASSERT(!IS_ERR(map));
 571
 572         num_extents = 0;
 573         cur_extent = 0;
 574         for (i = 0; i < map->num_stripes; i++) {
 575                 /* We have more device extent to copy */
 576                 if (srcdev != map->stripes[i].dev)
 577                         continue;
 578
 579                 num_extents++;
 580                 if (physical == map->stripes[i].physical)
 581                         cur_extent = i;
 582         }
 583
 584         btrfs_free_chunk_map(map);
 585
 586         if (num_extents > 1 && cur_extent < num_extents - 1) {
 587                 /*
 588                  * Has more stripes on this device. Keep this block group
 589                  * readonly until we finish all the stripes.
 590                  */
 591                 return false;
 592         }
 593
 594         /* Last stripe on this device */
 595         clear_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
 596
 597         return true;
 598 }
 599
 600 static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 601                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
 602                 int read_src)
 603 {
 604         struct btrfs_root *root = fs_info->dev_root;
 605         struct btrfs_trans_handle *trans;
 606         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 607         int ret;
 608         struct btrfs_device *tgt_device = NULL;
 609         struct btrfs_device *src_device = NULL;
 610
 611         src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,
 612                                                   srcdev_name);
 613         if (IS_ERR(src_device))
 614                 return PTR_ERR(src_device);
 615
 616         if (btrfs_pinned_by_swapfile(fs_info, src_device)) {
 617                 btrfs_warn_in_rcu(fs_info,
 618           "cannot replace device %s (devid %llu) due to active swapfile",
 619                         btrfs_dev_name(src_device), src_device->devid);
 620                 return -ETXTBSY;
 621         }
 622
 623         /*
 624          * Here we commit the transaction to make sure commit_total_bytes
 625          * of all the devices are updated.
 626          */
 627         trans = btrfs_attach_transaction(root);
 628         if (!IS_ERR(trans)) {
 629                 ret = btrfs_commit_transaction(trans);
 630                 if (ret)
 631                         return ret;
 632         } else if (PTR_ERR(trans) != -ENOENT) {
 633                 return PTR_ERR(trans);
 634         }
 635
 636         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 637                                             src_device, &tgt_device);
 638         if (ret)
 639                 return ret;
 640
 641         ret = mark_block_group_to_copy(fs_info, src_device);
 642         if (ret)
 643                 return ret;
 644
 645         down_write(&dev_replace->rwsem);
 646         switch (dev_replace->replace_state) {
 647         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 648         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 649         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 650                 break;
 651         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 652         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 653                 ASSERT(0);
 654                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 655                 up_write(&dev_replace->rwsem);
 656                 goto leave;
 657         }
 658
 659         dev_replace->cont_reading_from_srcdev_mode = read_src;
 660         dev_replace->srcdev = src_device;
 661         dev_replace->tgtdev = tgt_device;
 662
 663         btrfs_info_in_rcu(fs_info,
 664                       "dev_replace from %s (devid %llu) to %s started",
 665                       btrfs_dev_name(src_device),
 666                       src_device->devid,
 667                       btrfs_dev_name(tgt_device));
 668
 669         /*
 670          * from now on, the writes to the srcdev are all duplicated to
 671          * go to the tgtdev as well (refer to btrfs_map_block()).
 672          */
 673         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 674         dev_replace->time_started = ktime_get_real_seconds();
 675         dev_replace->cursor_left = 0;
 676         dev_replace->committed_cursor_left = 0;
 677         dev_replace->cursor_left_last_write_of_item = 0;
 678         dev_replace->cursor_right = 0;
 679         dev_replace->is_valid = 1;
 680         dev_replace->item_needs_writeback = 1;
 681         atomic64_set(&dev_replace->num_write_errors, 0);
 682         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 683         up_write(&dev_replace->rwsem);
 684
 685         ret = btrfs_sysfs_add_device(tgt_device);
 686         if (ret)
 687                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 688
 689         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 690
 691         /*
 692          * Commit dev_replace state and reserve 1 item for it.
 693          * This is crucial to ensure we won't miss copying extents for new block
 694          * groups that are allocated after we started the device replace, and
 695          * must be done after setting up the device replace state.
 696          */
 697         trans = btrfs_start_transaction(root, 1);
 698         if (IS_ERR(trans)) {
 699                 ret = PTR_ERR(trans);
 700                 down_write(&dev_replace->rwsem);
 701                 dev_replace->replace_state =
 702                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 703                 dev_replace->srcdev = NULL;
 704                 dev_replace->tgtdev = NULL;
 705                 up_write(&dev_replace->rwsem);
 706                 goto leave;
 707         }
 708
 709         ret = btrfs_commit_transaction(trans);
 710         WARN_ON(ret);
 711
 712         /* the disk copy procedure reuses the scrub code */
 713         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 714                               btrfs_device_get_total_bytes(src_device),
 715                               &dev_replace->scrub_progress, 0, 1);
 716
 717         ret = btrfs_dev_replace_finishing(fs_info, ret);
 718         if (ret == -EINPROGRESS)
 719                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 720
 721         return ret;
 722
 723 leave:
 724         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 725         return ret;
 726 }
 727
 728 static int btrfs_check_replace_dev_names(struct btrfs_ioctl_dev_replace_args *args)
 729 {
 730         if (args->start.srcdevid == 0) {
 731                 if (memchr(args->start.srcdev_name, 0,
 732                            sizeof(args->start.srcdev_name)) == NULL)
 733                         return -ENAMETOOLONG;
 734         } else {
 735                 args->start.srcdev_name[0] = 0;
 736         }
 737
 738         if (memchr(args->start.tgtdev_name, 0,
 739                    sizeof(args->start.tgtdev_name)) == NULL)
 740             return -ENAMETOOLONG;
 741
 742         return 0;
 743 }
 744
 745 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 746                             struct btrfs_ioctl_dev_replace_args *args)
 747 {
 748         int ret;
 749
 750         switch (args->start.cont_reading_from_srcdev_mode) {
 751         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 752         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 753                 break;
 754         default:
 755                 return -EINVAL;
 756         }
 757         ret = btrfs_check_replace_dev_names(args);
 758         if (ret < 0)
 759                 return ret;
 760
 761         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 762                                         args->start.srcdevid,
 763                                         args->start.srcdev_name,
 764                                         args->start.cont_reading_from_srcdev_mode);
 765         args->result = ret;
 766         /* don't warn if EINPROGRESS, someone else might be running scrub */
 767         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS ||
 768             ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR)
 769                 return 0;
 770
 771         return ret;
 772 }
 773
 774 /*
 775  * blocked until all in-flight bios operations are finished.
 776  */
 777 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 778 {
 779         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 780         wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
 781                    &fs_info->dev_replace.bio_counter));
 782 }
 783
 784 /*
 785  * we have removed target device, it is safe to allow new bios request.
 786  */
 787 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 788 {
 789         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 790         wake_up(&fs_info->dev_replace.replace_wait);
 791 }
 792
 793 /*
 794  * When finishing the device replace, before swapping the source device with the
 795  * target device we must update the chunk allocation state in the target device,
 796  * as it is empty because replace works by directly copying the chunks and not
 797  * through the normal chunk allocation path.
 798  */
 799 static int btrfs_set_target_alloc_state(struct btrfs_device *srcdev,
 800                                         struct btrfs_device *tgtdev)
 801 {
 802         struct extent_state *cached_state = NULL;
 803         u64 start = 0;
 804         u64 found_start;
 805         u64 found_end;
 806         int ret = 0;
 807
 808         lockdep_assert_held(&srcdev->fs_info->chunk_mutex);
 809
 810         while (find_first_extent_bit(&srcdev->alloc_state, start,
 811                                      &found_start, &found_end,
 812                                      CHUNK_ALLOCATED, &cached_state)) {
 813                 ret = set_extent_bit(&tgtdev->alloc_state, found_start,
 814                                      found_end, CHUNK_ALLOCATED, NULL);
 815                 if (ret)
 816                         break;
 817                 start = found_end + 1;
 818         }
 819
 820         free_extent_state(cached_state);
 821         return ret;
 822 }
 823
 824 static void btrfs_dev_replace_update_device_in_mapping_tree(
 825                                                 struct btrfs_fs_info *fs_info,
 826                                                 struct btrfs_device *srcdev,
 827                                                 struct btrfs_device *tgtdev)
 828 {
 829         u64 start = 0;
 830         int i;
 831
 832         write_lock(&fs_info->mapping_tree_lock);
 833         do {
 834                 struct btrfs_chunk_map *map;
 835
 836                 map = btrfs_find_chunk_map_nolock(fs_info, start, U64_MAX);
 837                 if (!map)
 838                         break;
 839                 for (i = 0; i < map->num_stripes; i++)
 840                         if (srcdev == map->stripes[i].dev)
 841                                 map->stripes[i].dev = tgtdev;
 842                 start = map->start + map->chunk_len;
 843                 btrfs_free_chunk_map(map);
 844         } while (start);
 845         write_unlock(&fs_info->mapping_tree_lock);
 846 }
 847
 848 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 849                                        int scrub_ret)
 850 {
 851         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 852         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 853         struct btrfs_device *tgt_device;
 854         struct btrfs_device *src_device;
 855         struct btrfs_root *root = fs_info->tree_root;
 856         u8 uuid_tmp[BTRFS_UUID_SIZE];
 857         struct btrfs_trans_handle *trans;
 858         int ret = 0;
 859
 860         /* don't allow cancel or unmount to disturb the finishing procedure */
 861         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 862
 863         down_read(&dev_replace->rwsem);
 864         /* was the operation canceled, or is it finished? */
 865         if (dev_replace->replace_state !=
 866             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 867                 up_read(&dev_replace->rwsem);
 868                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 869                 return 0;
 870         }
 871
 872         tgt_device = dev_replace->tgtdev;
 873         src_device = dev_replace->srcdev;
 874         up_read(&dev_replace->rwsem);
 875
 876         /*
 877          * flush all outstanding I/O and inode extent mappings before the
 878          * copy operation is declared as being finished
 879          */
 880         ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
 881         if (ret) {
 882                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 883                 return ret;
 884         }
 885         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 886
 887         /*
 888          * We have to use this loop approach because at this point src_device
 889          * has to be available for transaction commit to complete, yet new
 890          * chunks shouldn't be allocated on the device.
 891          */
 892         while (1) {
 893                 trans = btrfs_start_transaction(root, 0);
 894                 if (IS_ERR(trans)) {
 895                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 896                         return PTR_ERR(trans);
 897                 }
 898                 ret = btrfs_commit_transaction(trans);
 899                 WARN_ON(ret);
 900
 901                 /* Prevent write_all_supers() during the finishing procedure */
 902                 mutex_lock(&fs_devices->device_list_mutex);
 903                 /* Prevent new chunks being allocated on the source device */
 904                 mutex_lock(&fs_info->chunk_mutex);
 905
 906                 if (!list_empty(&src_device->post_commit_list)) {
 907                         mutex_unlock(&fs_devices->device_list_mutex);
 908                         mutex_unlock(&fs_info->chunk_mutex);
 909                 } else {
 910                         break;
 911                 }
 912         }
 913
 914         down_write(&dev_replace->rwsem);
 915         dev_replace->replace_state =
 916                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 917                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 918         dev_replace->tgtdev = NULL;
 919         dev_replace->srcdev = NULL;
 920         dev_replace->time_stopped = ktime_get_real_seconds();
 921         dev_replace->item_needs_writeback = 1;
 922
 923         /*
 924          * Update allocation state in the new device and replace the old device
 925          * with the new one in the mapping tree.
 926          */
 927         if (!scrub_ret) {
 928                 scrub_ret = btrfs_set_target_alloc_state(src_device, tgt_device);
 929                 if (scrub_ret)
 930                         goto error;
 931                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 932                                                                 src_device,
 933                                                                 tgt_device);
 934         } else {
 935                 if (scrub_ret != -ECANCELED)
 936                         btrfs_err_in_rcu(fs_info,
 937                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 938                                  btrfs_dev_name(src_device),
 939                                  src_device->devid,
 940                                  btrfs_dev_name(tgt_device), scrub_ret);
 941 error:
 942                 up_write(&dev_replace->rwsem);
 943                 mutex_unlock(&fs_info->chunk_mutex);
 944                 mutex_unlock(&fs_devices->device_list_mutex);
 945                 btrfs_rm_dev_replace_blocked(fs_info);
 946                 if (tgt_device)
 947                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 948                 btrfs_rm_dev_replace_unblocked(fs_info);
 949                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 950
 951                 return scrub_ret;
 952         }
 953
 954         btrfs_info_in_rcu(fs_info,
 955                           "dev_replace from %s (devid %llu) to %s finished",
 956                           btrfs_dev_name(src_device),
 957                           src_device->devid,
 958                           btrfs_dev_name(tgt_device));
 959         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 960         tgt_device->devid = src_device->devid;
 961         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 962         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 963         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 964         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 965         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 966         btrfs_device_set_disk_total_bytes(tgt_device,
 967                                           src_device->disk_total_bytes);
 968         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 969         tgt_device->commit_bytes_used = src_device->bytes_used;
 970
 971         btrfs_assign_next_active_device(src_device, tgt_device);
 972
 973         list_add(&tgt_device->dev_alloc_list, &fs_devices->alloc_list);
 974         fs_devices->rw_devices++;
 975
 976         up_write(&dev_replace->rwsem);
 977         btrfs_rm_dev_replace_blocked(fs_info);
 978
 979         btrfs_rm_dev_replace_remove_srcdev(src_device);
 980
 981         btrfs_rm_dev_replace_unblocked(fs_info);
 982
 983         /*
 984          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
 985          * update on-disk dev stats value during commit transaction
 986          */
 987         atomic_inc(&tgt_device->dev_stats_ccnt);
 988
 989         /*
 990          * this is again a consistent state where no dev_replace procedure
 991          * is running, the target device is part of the filesystem, the
 992          * source device is not part of the filesystem anymore and its 1st
 993          * superblock is scratched out so that it is no longer marked to
 994          * belong to this filesystem.
 995          */
 996         mutex_unlock(&fs_info->chunk_mutex);
 997         mutex_unlock(&fs_devices->device_list_mutex);
 998
 999         /* replace the sysfs entry */
1000         btrfs_sysfs_remove_device(src_device);
1001         btrfs_sysfs_update_devid(tgt_device);
1002         if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &src_device->dev_state))
1003                 btrfs_scratch_superblocks(fs_info, src_device->bdev,
1004                                           src_device->name->str);
1005
1006         /* write back the superblocks */
1007         trans = btrfs_start_transaction(root, 0);
1008         if (!IS_ERR(trans))
1009                 btrfs_commit_transaction(trans);
1010
1011         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1012
1013         btrfs_rm_dev_replace_free_srcdev(src_device);
1014
1015         return 0;
1016 }
1017
1018 /*
1019  * Read progress of device replace status according to the state and last
1020  * stored position. The value format is the same as for
1021  * btrfs_dev_replace::progress_1000
1022  */
1023 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
1024 {
1025         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1026         u64 ret = 0;
1027
1028         switch (dev_replace->replace_state) {
1029         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1030         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1031                 ret = 0;
1032                 break;
1033         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1034                 ret = 1000;
1035                 break;
1036         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1037         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1038                 ret = div64_u64(dev_replace->cursor_left,
1039                                 div_u64(btrfs_device_get_total_bytes(
1040                                                 dev_replace->srcdev), 1000));
1041                 break;
1042         }
1043
1044         return ret;
1045 }
1046
1047 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
1048                               struct btrfs_ioctl_dev_replace_args *args)
1049 {
1050         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1051
1052         down_read(&dev_replace->rwsem);
1053         /* even if !dev_replace_is_valid, the values are good enough for
1054          * the replace_status ioctl */
1055         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1056         args->status.replace_state = dev_replace->replace_state;
1057         args->status.time_started = dev_replace->time_started;
1058         args->status.time_stopped = dev_replace->time_stopped;
1059         args->status.num_write_errors =
1060                 atomic64_read(&dev_replace->num_write_errors);
1061         args->status.num_uncorrectable_read_errors =
1062                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
1063         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
1064         up_read(&dev_replace->rwsem);
1065 }
1066
1067 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
1068 {
1069         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1070         struct btrfs_device *tgt_device = NULL;
1071         struct btrfs_device *src_device = NULL;
1072         struct btrfs_trans_handle *trans;
1073         struct btrfs_root *root = fs_info->tree_root;
1074         int result;
1075         int ret;
1076
1077         if (sb_rdonly(fs_info->sb))
1078                 return -EROFS;
1079
1080         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
1081         down_write(&dev_replace->rwsem);
1082         switch (dev_replace->replace_state) {
1083         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1084         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1085         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1086                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
1087                 up_write(&dev_replace->rwsem);
1088                 break;
1089         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1090                 tgt_device = dev_replace->tgtdev;
1091                 src_device = dev_replace->srcdev;
1092                 up_write(&dev_replace->rwsem);
1093                 ret = btrfs_scrub_cancel(fs_info);
1094                 if (ret < 0) {
1095                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
1096                 } else {
1097                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1098                         /*
1099                          * btrfs_dev_replace_finishing() will handle the
1100                          * cleanup part
1101                          */
1102                         btrfs_info_in_rcu(fs_info,
1103                                 "dev_replace from %s (devid %llu) to %s canceled",
1104                                 btrfs_dev_name(src_device), src_device->devid,
1105                                 btrfs_dev_name(tgt_device));
1106                 }
1107                 break;
1108         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1109                 /*
1110                  * Scrub doing the replace isn't running so we need to do the
1111                  * cleanup step of btrfs_dev_replace_finishing() here
1112                  */
1113                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1114                 tgt_device = dev_replace->tgtdev;
1115                 src_device = dev_replace->srcdev;
1116                 dev_replace->tgtdev = NULL;
1117                 dev_replace->srcdev = NULL;
1118                 dev_replace->replace_state =
1119                                 BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
1120                 dev_replace->time_stopped = ktime_get_real_seconds();
1121                 dev_replace->item_needs_writeback = 1;
1122
1123                 up_write(&dev_replace->rwsem);
1124
1125                 /* Scrub for replace must not be running in suspended state */
1126                 btrfs_scrub_cancel(fs_info);
1127
1128                 trans = btrfs_start_transaction(root, 0);
1129                 if (IS_ERR(trans)) {
1130                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1131                         return PTR_ERR(trans);
1132                 }
1133                 ret = btrfs_commit_transaction(trans);
1134                 WARN_ON(ret);
1135
1136                 btrfs_info_in_rcu(fs_info,
1137                 "suspended dev_replace from %s (devid %llu) to %s canceled",
1138                         btrfs_dev_name(src_device), src_device->devid,
1139                         btrfs_dev_name(tgt_device));
1140
1141                 if (tgt_device)
1142                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
1143                 break;
1144         default:
1145                 up_write(&dev_replace->rwsem);
1146                 result = -EINVAL;
1147         }
1148
1149         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1150         return result;
1151 }
1152
1153 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
1154 {
1155         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1156
1157         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
1158         down_write(&dev_replace->rwsem);
1159
1160         switch (dev_replace->replace_state) {
1161         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1162         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1163         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1164         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1165                 break;
1166         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1167                 dev_replace->replace_state =
1168                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1169                 dev_replace->time_stopped = ktime_get_real_seconds();
1170                 dev_replace->item_needs_writeback = 1;
1171                 btrfs_info(fs_info, "suspending dev_replace for unmount");
1172                 break;
1173         }
1174
1175         up_write(&dev_replace->rwsem);
1176         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1177 }
1178
1179 /* resume dev_replace procedure that was interrupted by unmount */
1180 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
1181 {
1182         struct task_struct *task;
1183         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1184
1185         down_write(&dev_replace->rwsem);
1186
1187         switch (dev_replace->replace_state) {
1188         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1189         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1190         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1191                 up_write(&dev_replace->rwsem);
1192                 return 0;
1193         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1194                 break;
1195         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1196                 dev_replace->replace_state =
1197                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
1198                 break;
1199         }
1200         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
1201                 btrfs_info(fs_info,
1202                            "cannot continue dev_replace, tgtdev is missing");
1203                 btrfs_info(fs_info,
1204                            "you may cancel the operation after 'mount -o degraded'");
1205                 dev_replace->replace_state =
1206                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1207                 up_write(&dev_replace->rwsem);
1208                 return 0;
1209         }
1210         up_write(&dev_replace->rwsem);
1211
1212         /*
1213          * This could collide with a paused balance, but the exclusive op logic
1214          * should never allow both to start and pause. We don't want to allow
1215          * dev-replace to start anyway.
1216          */
1217         if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
1218                 down_write(&dev_replace->rwsem);
1219                 dev_replace->replace_state =
1220                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1221                 up_write(&dev_replace->rwsem);
1222                 btrfs_info(fs_info,
1223                 "cannot resume dev-replace, other exclusive operation running");
1224                 return 0;
1225         }
1226
1227         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
1228         return PTR_ERR_OR_ZERO(task);
1229 }
1230
1231 static int btrfs_dev_replace_kthread(void *data)
1232 {
1233         struct btrfs_fs_info *fs_info = data;
1234         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1235         u64 progress;
1236         int ret;
1237
1238         progress = btrfs_dev_replace_progress(fs_info);
1239         progress = div_u64(progress, 10);
1240         btrfs_info_in_rcu(fs_info,
1241                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
1242                 btrfs_dev_name(dev_replace->srcdev),
1243                 dev_replace->srcdev->devid,
1244                 btrfs_dev_name(dev_replace->tgtdev),
1245                 (unsigned int)progress);
1246
1247         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
1248                               dev_replace->committed_cursor_left,
1249                               btrfs_device_get_total_bytes(dev_replace->srcdev),
1250                               &dev_replace->scrub_progress, 0, 1);
1251         ret = btrfs_dev_replace_finishing(fs_info, ret);
1252         WARN_ON(ret && ret != -ECANCELED);
1253
1254         btrfs_exclop_finish(fs_info);
1255         return 0;
1256 }
1257
1258 int __pure btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
1259 {
1260         if (!dev_replace->is_valid)
1261                 return 0;
1262
1263         switch (dev_replace->replace_state) {
1264         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1265         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1266         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1267                 return 0;
1268         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1269         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1270                 /*
1271                  * return true even if tgtdev is missing (this is
1272                  * something that can happen if the dev_replace
1273                  * procedure is suspended by an umount and then
1274                  * the tgtdev is missing (or "btrfs dev scan") was
1275                  * not called and the filesystem is remounted
1276                  * in degraded state. This does not stop the
1277                  * dev_replace procedure. It needs to be canceled
1278                  * manually if the cancellation is wanted.
1279                  */
1280                 break;
1281         }
1282         return 1;
1283 }
1284
1285 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1286 {
1287         percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1288         cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1289 }
1290
1291 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1292 {
1293         while (1) {
1294                 percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1295                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1296                                      &fs_info->fs_state)))
1297                         break;
1298
1299                 btrfs_bio_counter_dec(fs_info);
1300                 wait_event(fs_info->dev_replace.replace_wait,
1301                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1302                                      &fs_info->fs_state));
1303         }
1304 }