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