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