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/buffer_head.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/random.h>
  12 #include <linux/iocontext.h>
  13 #include <linux/capability.h>
  14 #include <linux/kthread.h>
  15 #include <linux/math64.h>
  16 #include <asm/div64.h>
  17 #include "ctree.h"
  18 #include "extent_map.h"
  19 #include "disk-io.h"
  20 #include "transaction.h"
  21 #include "print-tree.h"
  22 #include "volumes.h"
  23 #include "async-thread.h"
  24 #include "check-integrity.h"
  25 #include "rcu-string.h"
  26 #include "dev-replace.h"
  27 #include "sysfs.h"
  28
  29 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
  30                                        int scrub_ret);
  31 static void btrfs_dev_replace_update_device_in_mapping_tree(
  32                                                 struct btrfs_fs_info *fs_info,
  33                                                 struct btrfs_device *srcdev,
  34                                                 struct btrfs_device *tgtdev);
  35 static int btrfs_dev_replace_kthread(void *data);
  36 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
  37
  38
  39 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  40 {
  41         struct btrfs_key key;
  42         struct btrfs_root *dev_root = fs_info->dev_root;
  43         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  44         struct extent_buffer *eb;
  45         int slot;
  46         int ret = 0;
  47         struct btrfs_path *path = NULL;
  48         int item_size;
  49         struct btrfs_dev_replace_item *ptr;
  50         u64 src_devid;
  51
  52         path = btrfs_alloc_path();
  53         if (!path) {
  54                 ret = -ENOMEM;
  55                 goto out;
  56         }
  57
  58         key.objectid = 0;
  59         key.type = BTRFS_DEV_REPLACE_KEY;
  60         key.offset = 0;
  61         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  62         if (ret) {
  63 no_valid_dev_replace_entry_found:
  64                 ret = 0;
  65                 dev_replace->replace_state =
  66                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
  67                 dev_replace->cont_reading_from_srcdev_mode =
  68                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
  69                 dev_replace->replace_state = 0;
  70                 dev_replace->time_started = 0;
  71                 dev_replace->time_stopped = 0;
  72                 atomic64_set(&dev_replace->num_write_errors, 0);
  73                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
  74                 dev_replace->cursor_left = 0;
  75                 dev_replace->committed_cursor_left = 0;
  76                 dev_replace->cursor_left_last_write_of_item = 0;
  77                 dev_replace->cursor_right = 0;
  78                 dev_replace->srcdev = NULL;
  79                 dev_replace->tgtdev = NULL;
  80                 dev_replace->is_valid = 0;
  81                 dev_replace->item_needs_writeback = 0;
  82                 goto out;
  83         }
  84         slot = path->slots[0];
  85         eb = path->nodes[0];
  86         item_size = btrfs_item_size_nr(eb, slot);
  87         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
  88
  89         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
  90                 btrfs_warn(fs_info,
  91                         "dev_replace entry found has unexpected size, ignore entry");
  92                 goto no_valid_dev_replace_entry_found;
  93         }
  94
  95         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
  96         dev_replace->cont_reading_from_srcdev_mode =
  97                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
  98         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
  99         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
 100         dev_replace->time_stopped =
 101                 btrfs_dev_replace_time_stopped(eb, ptr);
 102         atomic64_set(&dev_replace->num_write_errors,
 103                      btrfs_dev_replace_num_write_errors(eb, ptr));
 104         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 105                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 106         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 107         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 108         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 109         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 110         dev_replace->is_valid = 1;
 111
 112         dev_replace->item_needs_writeback = 0;
 113         switch (dev_replace->replace_state) {
 114         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 115         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 116         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 117                 dev_replace->srcdev = NULL;
 118                 dev_replace->tgtdev = NULL;
 119                 break;
 120         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 121         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 122                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
 123                                                         NULL, NULL);
 124                 dev_replace->tgtdev = btrfs_find_device(fs_info,
 125                                                         BTRFS_DEV_REPLACE_DEVID,
 126                                                         NULL, NULL);
 127                 /*
 128                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 129                  * missing
 130                  */
 131                 if (!dev_replace->srcdev &&
 132                     !btrfs_test_opt(fs_info, DEGRADED)) {
 133                         ret = -EIO;
 134                         btrfs_warn(fs_info,
 135                            "cannot mount because device replace operation is ongoing and");
 136                         btrfs_warn(fs_info,
 137                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 138                            src_devid);
 139                 }
 140                 if (!dev_replace->tgtdev &&
 141                     !btrfs_test_opt(fs_info, DEGRADED)) {
 142                         ret = -EIO;
 143                         btrfs_warn(fs_info,
 144                            "cannot mount because device replace operation is ongoing and");
 145                         btrfs_warn(fs_info,
 146                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 147                                 BTRFS_DEV_REPLACE_DEVID);
 148                 }
 149                 if (dev_replace->tgtdev) {
 150                         if (dev_replace->srcdev) {
 151                                 dev_replace->tgtdev->total_bytes =
 152                                         dev_replace->srcdev->total_bytes;
 153                                 dev_replace->tgtdev->disk_total_bytes =
 154                                         dev_replace->srcdev->disk_total_bytes;
 155                                 dev_replace->tgtdev->commit_total_bytes =
 156                                         dev_replace->srcdev->commit_total_bytes;
 157                                 dev_replace->tgtdev->bytes_used =
 158                                         dev_replace->srcdev->bytes_used;
 159                                 dev_replace->tgtdev->commit_bytes_used =
 160                                         dev_replace->srcdev->commit_bytes_used;
 161                         }
 162                         set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
 163                                 &dev_replace->tgtdev->dev_state);
 164
 165                         WARN_ON(fs_info->fs_devices->rw_devices == 0);
 166                         dev_replace->tgtdev->io_width = fs_info->sectorsize;
 167                         dev_replace->tgtdev->io_align = fs_info->sectorsize;
 168                         dev_replace->tgtdev->sector_size = fs_info->sectorsize;
 169                         dev_replace->tgtdev->fs_info = fs_info;
 170                         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
 171                                 &dev_replace->tgtdev->dev_state);
 172                 }
 173                 break;
 174         }
 175
 176 out:
 177         btrfs_free_path(path);
 178         return ret;
 179 }
 180
 181 /*
 182  * called from commit_transaction. Writes changed device replace state to
 183  * disk.
 184  */
 185 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 186                           struct btrfs_fs_info *fs_info)
 187 {
 188         int ret;
 189         struct btrfs_root *dev_root = fs_info->dev_root;
 190         struct btrfs_path *path;
 191         struct btrfs_key key;
 192         struct extent_buffer *eb;
 193         struct btrfs_dev_replace_item *ptr;
 194         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 195
 196         btrfs_dev_replace_read_lock(dev_replace);
 197         if (!dev_replace->is_valid ||
 198             !dev_replace->item_needs_writeback) {
 199                 btrfs_dev_replace_read_unlock(dev_replace);
 200                 return 0;
 201         }
 202         btrfs_dev_replace_read_unlock(dev_replace);
 203
 204         key.objectid = 0;
 205         key.type = BTRFS_DEV_REPLACE_KEY;
 206         key.offset = 0;
 207
 208         path = btrfs_alloc_path();
 209         if (!path) {
 210                 ret = -ENOMEM;
 211                 goto out;
 212         }
 213         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 214         if (ret < 0) {
 215                 btrfs_warn(fs_info,
 216                            "error %d while searching for dev_replace item!",
 217                            ret);
 218                 goto out;
 219         }
 220
 221         if (ret == 0 &&
 222             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 223                 /*
 224                  * need to delete old one and insert a new one.
 225                  * Since no attempt is made to recover any old state, if the
 226                  * dev_replace state is 'running', the data on the target
 227                  * drive is lost.
 228                  * It would be possible to recover the state: just make sure
 229                  * that the beginning of the item is never changed and always
 230                  * contains all the essential information. Then read this
 231                  * minimal set of information and use it as a base for the
 232                  * new state.
 233                  */
 234                 ret = btrfs_del_item(trans, dev_root, path);
 235                 if (ret != 0) {
 236                         btrfs_warn(fs_info,
 237                                    "delete too small dev_replace item failed %d!",
 238                                    ret);
 239                         goto out;
 240                 }
 241                 ret = 1;
 242         }
 243
 244         if (ret == 1) {
 245                 /* need to insert a new item */
 246                 btrfs_release_path(path);
 247                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 248                                               &key, sizeof(*ptr));
 249                 if (ret < 0) {
 250                         btrfs_warn(fs_info,
 251                                    "insert dev_replace item failed %d!", ret);
 252                         goto out;
 253                 }
 254         }
 255
 256         eb = path->nodes[0];
 257         ptr = btrfs_item_ptr(eb, path->slots[0],
 258                              struct btrfs_dev_replace_item);
 259
 260         btrfs_dev_replace_write_lock(dev_replace);
 261         if (dev_replace->srcdev)
 262                 btrfs_set_dev_replace_src_devid(eb, ptr,
 263                         dev_replace->srcdev->devid);
 264         else
 265                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 266         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 267                 dev_replace->cont_reading_from_srcdev_mode);
 268         btrfs_set_dev_replace_replace_state(eb, ptr,
 269                 dev_replace->replace_state);
 270         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 271         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 272         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 273                 atomic64_read(&dev_replace->num_write_errors));
 274         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 275                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 276         dev_replace->cursor_left_last_write_of_item =
 277                 dev_replace->cursor_left;
 278         btrfs_set_dev_replace_cursor_left(eb, ptr,
 279                 dev_replace->cursor_left_last_write_of_item);
 280         btrfs_set_dev_replace_cursor_right(eb, ptr,
 281                 dev_replace->cursor_right);
 282         dev_replace->item_needs_writeback = 0;
 283         btrfs_dev_replace_write_unlock(dev_replace);
 284
 285         btrfs_mark_buffer_dirty(eb);
 286
 287 out:
 288         btrfs_free_path(path);
 289
 290         return ret;
 291 }
 292
 293 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 294 {
 295         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 296
 297         dev_replace->committed_cursor_left =
 298                 dev_replace->cursor_left_last_write_of_item;
 299 }
 300
 301 static char* btrfs_dev_name(struct btrfs_device *device)
 302 {
 303         if (!device || test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
 304                 return "<missing disk>";
 305         else
 306                 return rcu_str_deref(device->name);
 307 }
 308
 309 int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 310                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
 311                 int read_src)
 312 {
 313         struct btrfs_root *root = fs_info->dev_root;
 314         struct btrfs_trans_handle *trans;
 315         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 316         int ret;
 317         struct btrfs_device *tgt_device = NULL;
 318         struct btrfs_device *src_device = NULL;
 319
 320         /* the disk copy procedure reuses the scrub code */
 321         mutex_lock(&fs_info->volume_mutex);
 322         ret = btrfs_find_device_by_devspec(fs_info, srcdevid,
 323                                             srcdev_name, &src_device);
 324         if (ret) {
 325                 mutex_unlock(&fs_info->volume_mutex);
 326                 return ret;
 327         }
 328
 329         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 330                                             src_device, &tgt_device);
 331         mutex_unlock(&fs_info->volume_mutex);
 332         if (ret)
 333                 return ret;
 334
 335         /*
 336          * Here we commit the transaction to make sure commit_total_bytes
 337          * of all the devices are updated.
 338          */
 339         trans = btrfs_attach_transaction(root);
 340         if (!IS_ERR(trans)) {
 341                 ret = btrfs_commit_transaction(trans);
 342                 if (ret)
 343                         return ret;
 344         } else if (PTR_ERR(trans) != -ENOENT) {
 345                 return PTR_ERR(trans);
 346         }
 347
 348         btrfs_dev_replace_write_lock(dev_replace);
 349         switch (dev_replace->replace_state) {
 350         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 351         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 352         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 353                 break;
 354         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 355         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 356                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 357                 goto leave;
 358         }
 359
 360         dev_replace->cont_reading_from_srcdev_mode = read_src;
 361         WARN_ON(!src_device);
 362         dev_replace->srcdev = src_device;
 363         WARN_ON(!tgt_device);
 364         dev_replace->tgtdev = tgt_device;
 365
 366         btrfs_info_in_rcu(fs_info,
 367                       "dev_replace from %s (devid %llu) to %s started",
 368                       btrfs_dev_name(src_device),
 369                       src_device->devid,
 370                       rcu_str_deref(tgt_device->name));
 371
 372         /*
 373          * from now on, the writes to the srcdev are all duplicated to
 374          * go to the tgtdev as well (refer to btrfs_map_block()).
 375          */
 376         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 377         dev_replace->time_started = get_seconds();
 378         dev_replace->cursor_left = 0;
 379         dev_replace->committed_cursor_left = 0;
 380         dev_replace->cursor_left_last_write_of_item = 0;
 381         dev_replace->cursor_right = 0;
 382         dev_replace->is_valid = 1;
 383         dev_replace->item_needs_writeback = 1;
 384         atomic64_set(&dev_replace->num_write_errors, 0);
 385         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 386         btrfs_dev_replace_write_unlock(dev_replace);
 387
 388         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 389         if (ret)
 390                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 391
 392         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 393
 394         /* force writing the updated state information to disk */
 395         trans = btrfs_start_transaction(root, 0);
 396         if (IS_ERR(trans)) {
 397                 ret = PTR_ERR(trans);
 398                 btrfs_dev_replace_write_lock(dev_replace);
 399                 goto leave;
 400         }
 401
 402         ret = btrfs_commit_transaction(trans);
 403         WARN_ON(ret);
 404
 405         /* the disk copy procedure reuses the scrub code */
 406         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 407                               btrfs_device_get_total_bytes(src_device),
 408                               &dev_replace->scrub_progress, 0, 1);
 409
 410         ret = btrfs_dev_replace_finishing(fs_info, ret);
 411         if (ret == -EINPROGRESS) {
 412                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 413         } else {
 414                 WARN_ON(ret);
 415         }
 416
 417         return ret;
 418
 419 leave:
 420         dev_replace->srcdev = NULL;
 421         dev_replace->tgtdev = NULL;
 422         btrfs_dev_replace_write_unlock(dev_replace);
 423         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 424         return ret;
 425 }
 426
 427 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 428                             struct btrfs_ioctl_dev_replace_args *args)
 429 {
 430         int ret;
 431
 432         switch (args->start.cont_reading_from_srcdev_mode) {
 433         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 434         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 435                 break;
 436         default:
 437                 return -EINVAL;
 438         }
 439
 440         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 441             args->start.tgtdev_name[0] == '\0')
 442                 return -EINVAL;
 443
 444         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 445                                         args->start.srcdevid,
 446                                         args->start.srcdev_name,
 447                                         args->start.cont_reading_from_srcdev_mode);
 448         args->result = ret;
 449         /* don't warn if EINPROGRESS, someone else might be running scrub */
 450         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
 451                 ret = 0;
 452
 453         return ret;
 454 }
 455
 456 /*
 457  * blocked until all in-flight bios operations are finished.
 458  */
 459 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 460 {
 461         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 462         wait_event(fs_info->replace_wait, !percpu_counter_sum(
 463                    &fs_info->bio_counter));
 464 }
 465
 466 /*
 467  * we have removed target device, it is safe to allow new bios request.
 468  */
 469 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 470 {
 471         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 472         wake_up(&fs_info->replace_wait);
 473 }
 474
 475 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 476                                        int scrub_ret)
 477 {
 478         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 479         struct btrfs_device *tgt_device;
 480         struct btrfs_device *src_device;
 481         struct btrfs_root *root = fs_info->tree_root;
 482         u8 uuid_tmp[BTRFS_UUID_SIZE];
 483         struct btrfs_trans_handle *trans;
 484         int ret = 0;
 485
 486         /* don't allow cancel or unmount to disturb the finishing procedure */
 487         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 488
 489         btrfs_dev_replace_read_lock(dev_replace);
 490         /* was the operation canceled, or is it finished? */
 491         if (dev_replace->replace_state !=
 492             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 493                 btrfs_dev_replace_read_unlock(dev_replace);
 494                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 495                 return 0;
 496         }
 497
 498         tgt_device = dev_replace->tgtdev;
 499         src_device = dev_replace->srcdev;
 500         btrfs_dev_replace_read_unlock(dev_replace);
 501
 502         /*
 503          * flush all outstanding I/O and inode extent mappings before the
 504          * copy operation is declared as being finished
 505          */
 506         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
 507         if (ret) {
 508                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 509                 return ret;
 510         }
 511         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 512
 513         trans = btrfs_start_transaction(root, 0);
 514         if (IS_ERR(trans)) {
 515                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 516                 return PTR_ERR(trans);
 517         }
 518         ret = btrfs_commit_transaction(trans);
 519         WARN_ON(ret);
 520
 521         mutex_lock(&uuid_mutex);
 522         /* keep away write_all_supers() during the finishing procedure */
 523         mutex_lock(&fs_info->fs_devices->device_list_mutex);
 524         mutex_lock(&fs_info->chunk_mutex);
 525         btrfs_dev_replace_write_lock(dev_replace);
 526         dev_replace->replace_state =
 527                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 528                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 529         dev_replace->tgtdev = NULL;
 530         dev_replace->srcdev = NULL;
 531         dev_replace->time_stopped = get_seconds();
 532         dev_replace->item_needs_writeback = 1;
 533
 534         /* replace old device with new one in mapping tree */
 535         if (!scrub_ret) {
 536                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 537                                                                 src_device,
 538                                                                 tgt_device);
 539         } else {
 540                 btrfs_err_in_rcu(fs_info,
 541                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 542                                  btrfs_dev_name(src_device),
 543                                  src_device->devid,
 544                                  rcu_str_deref(tgt_device->name), scrub_ret);
 545                 btrfs_dev_replace_write_unlock(dev_replace);
 546                 mutex_unlock(&fs_info->chunk_mutex);
 547                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 548                 mutex_unlock(&uuid_mutex);
 549                 btrfs_rm_dev_replace_blocked(fs_info);
 550                 if (tgt_device)
 551                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 552                 btrfs_rm_dev_replace_unblocked(fs_info);
 553                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 554
 555                 return scrub_ret;
 556         }
 557
 558         btrfs_info_in_rcu(fs_info,
 559                           "dev_replace from %s (devid %llu) to %s finished",
 560                           btrfs_dev_name(src_device),
 561                           src_device->devid,
 562                           rcu_str_deref(tgt_device->name));
 563         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 564         tgt_device->devid = src_device->devid;
 565         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 566         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 567         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 568         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 569         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 570         btrfs_device_set_disk_total_bytes(tgt_device,
 571                                           src_device->disk_total_bytes);
 572         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 573         ASSERT(list_empty(&src_device->resized_list));
 574         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
 575         tgt_device->commit_bytes_used = src_device->bytes_used;
 576
 577         btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
 578
 579         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 580         fs_info->fs_devices->rw_devices++;
 581
 582         btrfs_dev_replace_write_unlock(dev_replace);
 583
 584         btrfs_rm_dev_replace_blocked(fs_info);
 585
 586         btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
 587
 588         btrfs_rm_dev_replace_unblocked(fs_info);
 589
 590         /*
 591          * this is again a consistent state where no dev_replace procedure
 592          * is running, the target device is part of the filesystem, the
 593          * source device is not part of the filesystem anymore and its 1st
 594          * superblock is scratched out so that it is no longer marked to
 595          * belong to this filesystem.
 596          */
 597         mutex_unlock(&fs_info->chunk_mutex);
 598         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 599         mutex_unlock(&uuid_mutex);
 600
 601         /* replace the sysfs entry */
 602         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
 603         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 604
 605         /* write back the superblocks */
 606         trans = btrfs_start_transaction(root, 0);
 607         if (!IS_ERR(trans))
 608                 btrfs_commit_transaction(trans);
 609
 610         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 611
 612         return 0;
 613 }
 614
 615 static void btrfs_dev_replace_update_device_in_mapping_tree(
 616                                                 struct btrfs_fs_info *fs_info,
 617                                                 struct btrfs_device *srcdev,
 618                                                 struct btrfs_device *tgtdev)
 619 {
 620         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 621         struct extent_map *em;
 622         struct map_lookup *map;
 623         u64 start = 0;
 624         int i;
 625
 626         write_lock(&em_tree->lock);
 627         do {
 628                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 629                 if (!em)
 630                         break;
 631                 map = em->map_lookup;
 632                 for (i = 0; i < map->num_stripes; i++)
 633                         if (srcdev == map->stripes[i].dev)
 634                                 map->stripes[i].dev = tgtdev;
 635                 start = em->start + em->len;
 636                 free_extent_map(em);
 637         } while (start);
 638         write_unlock(&em_tree->lock);
 639 }
 640
 641 /*
 642  * Read progress of device replace status according to the state and last
 643  * stored position. The value format is the same as for
 644  * btrfs_dev_replace::progress_1000
 645  */
 646 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
 647 {
 648         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 649         u64 ret = 0;
 650
 651         switch (dev_replace->replace_state) {
 652         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 653         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 654                 ret = 0;
 655                 break;
 656         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 657                 ret = 1000;
 658                 break;
 659         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 660         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 661                 ret = div64_u64(dev_replace->cursor_left,
 662                                 div_u64(btrfs_device_get_total_bytes(
 663                                                 dev_replace->srcdev), 1000));
 664                 break;
 665         }
 666
 667         return ret;
 668 }
 669
 670 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 671                               struct btrfs_ioctl_dev_replace_args *args)
 672 {
 673         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 674
 675         btrfs_dev_replace_read_lock(dev_replace);
 676         /* even if !dev_replace_is_valid, the values are good enough for
 677          * the replace_status ioctl */
 678         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 679         args->status.replace_state = dev_replace->replace_state;
 680         args->status.time_started = dev_replace->time_started;
 681         args->status.time_stopped = dev_replace->time_stopped;
 682         args->status.num_write_errors =
 683                 atomic64_read(&dev_replace->num_write_errors);
 684         args->status.num_uncorrectable_read_errors =
 685                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 686         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
 687         btrfs_dev_replace_read_unlock(dev_replace);
 688 }
 689
 690 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 691 {
 692         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 693         struct btrfs_device *tgt_device = NULL;
 694         struct btrfs_device *src_device = NULL;
 695         struct btrfs_trans_handle *trans;
 696         struct btrfs_root *root = fs_info->tree_root;
 697         int result;
 698         int ret;
 699
 700         if (sb_rdonly(fs_info->sb))
 701                 return -EROFS;
 702
 703         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 704         btrfs_dev_replace_write_lock(dev_replace);
 705         switch (dev_replace->replace_state) {
 706         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 707         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 708         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 709                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 710                 btrfs_dev_replace_write_unlock(dev_replace);
 711                 goto leave;
 712         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 713         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 714                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 715                 tgt_device = dev_replace->tgtdev;
 716                 src_device = dev_replace->srcdev;
 717                 dev_replace->tgtdev = NULL;
 718                 dev_replace->srcdev = NULL;
 719                 break;
 720         }
 721         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 722         dev_replace->time_stopped = get_seconds();
 723         dev_replace->item_needs_writeback = 1;
 724         btrfs_dev_replace_write_unlock(dev_replace);
 725         btrfs_scrub_cancel(fs_info);
 726
 727         trans = btrfs_start_transaction(root, 0);
 728         if (IS_ERR(trans)) {
 729                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 730                 return PTR_ERR(trans);
 731         }
 732         ret = btrfs_commit_transaction(trans);
 733         WARN_ON(ret);
 734
 735         btrfs_info_in_rcu(fs_info,
 736                 "dev_replace from %s (devid %llu) to %s canceled",
 737                 btrfs_dev_name(src_device), src_device->devid,
 738                 btrfs_dev_name(tgt_device));
 739
 740         if (tgt_device)
 741                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 742
 743 leave:
 744         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 745         return result;
 746 }
 747
 748 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 749 {
 750         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 751
 752         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 753         btrfs_dev_replace_write_lock(dev_replace);
 754         switch (dev_replace->replace_state) {
 755         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 756         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 757         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 758         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 759                 break;
 760         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 761                 dev_replace->replace_state =
 762                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 763                 dev_replace->time_stopped = get_seconds();
 764                 dev_replace->item_needs_writeback = 1;
 765                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 766                 break;
 767         }
 768
 769         btrfs_dev_replace_write_unlock(dev_replace);
 770         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 771 }
 772
 773 /* resume dev_replace procedure that was interrupted by unmount */
 774 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 775 {
 776         struct task_struct *task;
 777         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 778
 779         btrfs_dev_replace_write_lock(dev_replace);
 780         switch (dev_replace->replace_state) {
 781         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 782         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 783         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 784                 btrfs_dev_replace_write_unlock(dev_replace);
 785                 return 0;
 786         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 787                 break;
 788         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 789                 dev_replace->replace_state =
 790                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 791                 break;
 792         }
 793         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 794                 btrfs_info(fs_info,
 795                            "cannot continue dev_replace, tgtdev is missing");
 796                 btrfs_info(fs_info,
 797                            "you may cancel the operation after 'mount -o degraded'");
 798                 btrfs_dev_replace_write_unlock(dev_replace);
 799                 return 0;
 800         }
 801         btrfs_dev_replace_write_unlock(dev_replace);
 802
 803         WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
 804         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 805         return PTR_ERR_OR_ZERO(task);
 806 }
 807
 808 static int btrfs_dev_replace_kthread(void *data)
 809 {
 810         struct btrfs_fs_info *fs_info = data;
 811         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 812         u64 progress;
 813
 814         progress = btrfs_dev_replace_progress(fs_info);
 815         progress = div_u64(progress, 10);
 816         btrfs_info_in_rcu(fs_info,
 817                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
 818                 btrfs_dev_name(dev_replace->srcdev),
 819                 dev_replace->srcdev->devid,
 820                 btrfs_dev_name(dev_replace->tgtdev),
 821                 (unsigned int)progress);
 822
 823         btrfs_dev_replace_continue_on_mount(fs_info);
 824         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
 825
 826         return 0;
 827 }
 828
 829 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 830 {
 831         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 832         int ret;
 833
 834         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 835                               dev_replace->committed_cursor_left,
 836                               btrfs_device_get_total_bytes(dev_replace->srcdev),
 837                               &dev_replace->scrub_progress, 0, 1);
 838         ret = btrfs_dev_replace_finishing(fs_info, ret);
 839         WARN_ON(ret);
 840         return 0;
 841 }
 842
 843 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 844 {
 845         if (!dev_replace->is_valid)
 846                 return 0;
 847
 848         switch (dev_replace->replace_state) {
 849         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 850         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 851         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 852                 return 0;
 853         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 854         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 855                 /*
 856                  * return true even if tgtdev is missing (this is
 857                  * something that can happen if the dev_replace
 858                  * procedure is suspended by an umount and then
 859                  * the tgtdev is missing (or "btrfs dev scan") was
 860                  * not called and the the filesystem is remounted
 861                  * in degraded state. This does not stop the
 862                  * dev_replace procedure. It needs to be canceled
 863                  * manually if the cancellation is wanted.
 864                  */
 865                 break;
 866         }
 867         return 1;
 868 }
 869
 870 void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace)
 871 {
 872         read_lock(&dev_replace->lock);
 873         atomic_inc(&dev_replace->read_locks);
 874 }
 875
 876 void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace)
 877 {
 878         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 879         atomic_dec(&dev_replace->read_locks);
 880         read_unlock(&dev_replace->lock);
 881 }
 882
 883 void btrfs_dev_replace_write_lock(struct btrfs_dev_replace *dev_replace)
 884 {
 885 again:
 886         wait_event(dev_replace->read_lock_wq,
 887                    atomic_read(&dev_replace->blocking_readers) == 0);
 888         write_lock(&dev_replace->lock);
 889         if (atomic_read(&dev_replace->blocking_readers)) {
 890                 write_unlock(&dev_replace->lock);
 891                 goto again;
 892         }
 893 }
 894
 895 void btrfs_dev_replace_write_unlock(struct btrfs_dev_replace *dev_replace)
 896 {
 897         ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
 898         write_unlock(&dev_replace->lock);
 899 }
 900
 901 /* inc blocking cnt and release read lock */
 902 void btrfs_dev_replace_set_lock_blocking(
 903                                         struct btrfs_dev_replace *dev_replace)
 904 {
 905         /* only set blocking for read lock */
 906         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 907         atomic_inc(&dev_replace->blocking_readers);
 908         read_unlock(&dev_replace->lock);
 909 }
 910
 911 /* acquire read lock and dec blocking cnt */
 912 void btrfs_dev_replace_clear_lock_blocking(
 913                                         struct btrfs_dev_replace *dev_replace)
 914 {
 915         /* only set blocking for read lock */
 916         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 917         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
 918         read_lock(&dev_replace->lock);
 919         if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
 920             waitqueue_active(&dev_replace->read_lock_wq))
 921                 wake_up(&dev_replace->read_lock_wq);
 922 }
 923
 924 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
 925 {
 926         percpu_counter_inc(&fs_info->bio_counter);
 927 }
 928
 929 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
 930 {
 931         percpu_counter_sub(&fs_info->bio_counter, amount);
 932
 933         if (waitqueue_active(&fs_info->replace_wait))
 934                 wake_up(&fs_info->replace_wait);
 935 }
 936
 937 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
 938 {
 939         while (1) {
 940                 percpu_counter_inc(&fs_info->bio_counter);
 941                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 942                                      &fs_info->fs_state)))
 943                         break;
 944
 945                 btrfs_bio_counter_dec(fs_info);
 946                 wait_event(fs_info->replace_wait,
 947                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 948                                      &fs_info->fs_state));
 949         }
 950 }