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