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->time_started = 0;
  63                 dev_replace->time_stopped = 0;
  64                 atomic64_set(&dev_replace->num_write_errors, 0);
  65                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
  66                 dev_replace->cursor_left = 0;
  67                 dev_replace->committed_cursor_left = 0;
  68                 dev_replace->cursor_left_last_write_of_item = 0;
  69                 dev_replace->cursor_right = 0;
  70                 dev_replace->srcdev = NULL;
  71                 dev_replace->tgtdev = NULL;
  72                 dev_replace->is_valid = 0;
  73                 dev_replace->item_needs_writeback = 0;
  74                 goto out;
  75         }
  76         slot = path->slots[0];
  77         eb = path->nodes[0];
  78         item_size = btrfs_item_size_nr(eb, slot);
  79         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
  80
  81         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
  82                 btrfs_warn(fs_info,
  83                         "dev_replace entry found has unexpected size, ignore entry");
  84                 goto no_valid_dev_replace_entry_found;
  85         }
  86
  87         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
  88         dev_replace->cont_reading_from_srcdev_mode =
  89                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
  90         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
  91         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
  92         dev_replace->time_stopped =
  93                 btrfs_dev_replace_time_stopped(eb, ptr);
  94         atomic64_set(&dev_replace->num_write_errors,
  95                      btrfs_dev_replace_num_write_errors(eb, ptr));
  96         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
  97                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
  98         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
  99         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 100         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 101         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 102         dev_replace->is_valid = 1;
 103
 104         dev_replace->item_needs_writeback = 0;
 105         switch (dev_replace->replace_state) {
 106         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 107         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 108         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 109                 dev_replace->srcdev = NULL;
 110                 dev_replace->tgtdev = NULL;
 111                 break;
 112         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 113         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 114                 dev_replace->srcdev = btrfs_find_device(fs_info->fs_devices,
 115                                                 src_devid, NULL, NULL, true);
 116                 dev_replace->tgtdev = btrfs_find_device(fs_info->fs_devices,
 117                                                         BTRFS_DEV_REPLACE_DEVID,
 118                                                         NULL, NULL, true);
 119                 /*
 120                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 121                  * missing
 122                  */
 123                 if (!dev_replace->srcdev &&
 124                     !btrfs_test_opt(fs_info, DEGRADED)) {
 125                         ret = -EIO;
 126                         btrfs_warn(fs_info,
 127                            "cannot mount because device replace operation is ongoing and");
 128                         btrfs_warn(fs_info,
 129                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 130                            src_devid);
 131                 }
 132                 if (!dev_replace->tgtdev &&
 133                     !btrfs_test_opt(fs_info, DEGRADED)) {
 134                         ret = -EIO;
 135                         btrfs_warn(fs_info,
 136                            "cannot mount because device replace operation is ongoing and");
 137                         btrfs_warn(fs_info,
 138                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 139                                 BTRFS_DEV_REPLACE_DEVID);
 140                 }
 141                 if (dev_replace->tgtdev) {
 142                         if (dev_replace->srcdev) {
 143                                 dev_replace->tgtdev->total_bytes =
 144                                         dev_replace->srcdev->total_bytes;
 145                                 dev_replace->tgtdev->disk_total_bytes =
 146                                         dev_replace->srcdev->disk_total_bytes;
 147                                 dev_replace->tgtdev->commit_total_bytes =
 148                                         dev_replace->srcdev->commit_total_bytes;
 149                                 dev_replace->tgtdev->bytes_used =
 150                                         dev_replace->srcdev->bytes_used;
 151                                 dev_replace->tgtdev->commit_bytes_used =
 152                                         dev_replace->srcdev->commit_bytes_used;
 153                         }
 154                         set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
 155                                 &dev_replace->tgtdev->dev_state);
 156
 157                         WARN_ON(fs_info->fs_devices->rw_devices == 0);
 158                         dev_replace->tgtdev->io_width = fs_info->sectorsize;
 159                         dev_replace->tgtdev->io_align = fs_info->sectorsize;
 160                         dev_replace->tgtdev->sector_size = fs_info->sectorsize;
 161                         dev_replace->tgtdev->fs_info = fs_info;
 162                         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
 163                                 &dev_replace->tgtdev->dev_state);
 164                 }
 165                 break;
 166         }
 167
 168 out:
 169         btrfs_free_path(path);
 170         return ret;
 171 }
 172
 173 /*
 174  * Initialize a new device for device replace target from a given source dev
 175  * and path.
 176  *
 177  * Return 0 and new device in @device_out, otherwise return < 0
 178  */
 179 static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 180                                   const char *device_path,
 181                                   struct btrfs_device *srcdev,
 182                                   struct btrfs_device **device_out)
 183 {
 184         struct btrfs_device *device;
 185         struct block_device *bdev;
 186         struct list_head *devices;
 187         struct rcu_string *name;
 188         u64 devid = BTRFS_DEV_REPLACE_DEVID;
 189         int ret = 0;
 190
 191         *device_out = NULL;
 192         if (fs_info->fs_devices->seeding) {
 193                 btrfs_err(fs_info, "the filesystem is a seed filesystem!");
 194                 return -EINVAL;
 195         }
 196
 197         bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
 198                                   fs_info->bdev_holder);
 199         if (IS_ERR(bdev)) {
 200                 btrfs_err(fs_info, "target device %s is invalid!", device_path);
 201                 return PTR_ERR(bdev);
 202         }
 203
 204         sync_blockdev(bdev);
 205
 206         devices = &fs_info->fs_devices->devices;
 207         list_for_each_entry(device, devices, dev_list) {
 208                 if (device->bdev == bdev) {
 209                         btrfs_err(fs_info,
 210                                   "target device is in the filesystem!");
 211                         ret = -EEXIST;
 212                         goto error;
 213                 }
 214         }
 215
 216
 217         if (i_size_read(bdev->bd_inode) <
 218             btrfs_device_get_total_bytes(srcdev)) {
 219                 btrfs_err(fs_info,
 220                           "target device is smaller than source device!");
 221                 ret = -EINVAL;
 222                 goto error;
 223         }
 224
 225
 226         device = btrfs_alloc_device(NULL, &devid, NULL);
 227         if (IS_ERR(device)) {
 228                 ret = PTR_ERR(device);
 229                 goto error;
 230         }
 231
 232         name = rcu_string_strdup(device_path, GFP_KERNEL);
 233         if (!name) {
 234                 btrfs_free_device(device);
 235                 ret = -ENOMEM;
 236                 goto error;
 237         }
 238         rcu_assign_pointer(device->name, name);
 239
 240         set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
 241         device->generation = 0;
 242         device->io_width = fs_info->sectorsize;
 243         device->io_align = fs_info->sectorsize;
 244         device->sector_size = fs_info->sectorsize;
 245         device->total_bytes = btrfs_device_get_total_bytes(srcdev);
 246         device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
 247         device->bytes_used = btrfs_device_get_bytes_used(srcdev);
 248         device->commit_total_bytes = srcdev->commit_total_bytes;
 249         device->commit_bytes_used = device->bytes_used;
 250         device->fs_info = fs_info;
 251         device->bdev = bdev;
 252         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 253         set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 254         device->mode = FMODE_EXCL;
 255         device->dev_stats_valid = 1;
 256         set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
 257         device->fs_devices = fs_info->fs_devices;
 258
 259         mutex_lock(&fs_info->fs_devices->device_list_mutex);
 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 {
 279         struct btrfs_fs_info *fs_info = trans->fs_info;
 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         down_read(&dev_replace->rwsem);
 289         if (!dev_replace->is_valid ||
 290             !dev_replace->item_needs_writeback) {
 291                 up_read(&dev_replace->rwsem);
 292                 return 0;
 293         }
 294         up_read(&dev_replace->rwsem);
 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         down_write(&dev_replace->rwsem);
 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         up_write(&dev_replace->rwsem);
 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 static 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         if (btrfs_pinned_by_swapfile(fs_info, src_device)) {
 411                 btrfs_warn_in_rcu(fs_info,
 412           "cannot replace device %s (devid %llu) due to active swapfile",
 413                         btrfs_dev_name(src_device), src_device->devid);
 414                 return -ETXTBSY;
 415         }
 416
 417         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 418                                             src_device, &tgt_device);
 419         if (ret)
 420                 return ret;
 421
 422         /*
 423          * Here we commit the transaction to make sure commit_total_bytes
 424          * of all the devices are updated.
 425          */
 426         trans = btrfs_attach_transaction(root);
 427         if (!IS_ERR(trans)) {
 428                 ret = btrfs_commit_transaction(trans);
 429                 if (ret)
 430                         return ret;
 431         } else if (PTR_ERR(trans) != -ENOENT) {
 432                 return PTR_ERR(trans);
 433         }
 434
 435         need_unlock = true;
 436         down_write(&dev_replace->rwsem);
 437         switch (dev_replace->replace_state) {
 438         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 439         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 440         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 441                 break;
 442         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 443         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 444                 ASSERT(0);
 445                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 446                 goto leave;
 447         }
 448
 449         dev_replace->cont_reading_from_srcdev_mode = read_src;
 450         WARN_ON(!src_device);
 451         dev_replace->srcdev = src_device;
 452         dev_replace->tgtdev = tgt_device;
 453
 454         btrfs_info_in_rcu(fs_info,
 455                       "dev_replace from %s (devid %llu) to %s started",
 456                       btrfs_dev_name(src_device),
 457                       src_device->devid,
 458                       rcu_str_deref(tgt_device->name));
 459
 460         /*
 461          * from now on, the writes to the srcdev are all duplicated to
 462          * go to the tgtdev as well (refer to btrfs_map_block()).
 463          */
 464         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 465         dev_replace->time_started = ktime_get_real_seconds();
 466         dev_replace->cursor_left = 0;
 467         dev_replace->committed_cursor_left = 0;
 468         dev_replace->cursor_left_last_write_of_item = 0;
 469         dev_replace->cursor_right = 0;
 470         dev_replace->is_valid = 1;
 471         dev_replace->item_needs_writeback = 1;
 472         atomic64_set(&dev_replace->num_write_errors, 0);
 473         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 474         up_write(&dev_replace->rwsem);
 475         need_unlock = false;
 476
 477         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 478         if (ret)
 479                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 480
 481         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 482
 483         /* force writing the updated state information to disk */
 484         trans = btrfs_start_transaction(root, 0);
 485         if (IS_ERR(trans)) {
 486                 ret = PTR_ERR(trans);
 487                 need_unlock = true;
 488                 down_write(&dev_replace->rwsem);
 489                 dev_replace->replace_state =
 490                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 491                 dev_replace->srcdev = NULL;
 492                 dev_replace->tgtdev = NULL;
 493                 goto leave;
 494         }
 495
 496         ret = btrfs_commit_transaction(trans);
 497         WARN_ON(ret);
 498
 499         /* the disk copy procedure reuses the scrub code */
 500         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 501                               btrfs_device_get_total_bytes(src_device),
 502                               &dev_replace->scrub_progress, 0, 1);
 503
 504         ret = btrfs_dev_replace_finishing(fs_info, ret);
 505         if (ret == -EINPROGRESS) {
 506                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 507         } else if (ret != -ECANCELED) {
 508                 WARN_ON(ret);
 509         }
 510
 511         return ret;
 512
 513 leave:
 514         if (need_unlock)
 515                 up_write(&dev_replace->rwsem);
 516         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 517         return ret;
 518 }
 519
 520 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 521                             struct btrfs_ioctl_dev_replace_args *args)
 522 {
 523         int ret;
 524
 525         switch (args->start.cont_reading_from_srcdev_mode) {
 526         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 527         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 528                 break;
 529         default:
 530                 return -EINVAL;
 531         }
 532
 533         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 534             args->start.tgtdev_name[0] == '\0')
 535                 return -EINVAL;
 536
 537         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 538                                         args->start.srcdevid,
 539                                         args->start.srcdev_name,
 540                                         args->start.cont_reading_from_srcdev_mode);
 541         args->result = ret;
 542         /* don't warn if EINPROGRESS, someone else might be running scrub */
 543         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS ||
 544             ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR)
 545                 return 0;
 546
 547         return ret;
 548 }
 549
 550 /*
 551  * blocked until all in-flight bios operations are finished.
 552  */
 553 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 554 {
 555         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 556         wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
 557                    &fs_info->dev_replace.bio_counter));
 558 }
 559
 560 /*
 561  * we have removed target device, it is safe to allow new bios request.
 562  */
 563 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 564 {
 565         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 566         wake_up(&fs_info->dev_replace.replace_wait);
 567 }
 568
 569 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 570                                        int scrub_ret)
 571 {
 572         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 573         struct btrfs_device *tgt_device;
 574         struct btrfs_device *src_device;
 575         struct btrfs_root *root = fs_info->tree_root;
 576         u8 uuid_tmp[BTRFS_UUID_SIZE];
 577         struct btrfs_trans_handle *trans;
 578         int ret = 0;
 579
 580         /* don't allow cancel or unmount to disturb the finishing procedure */
 581         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 582
 583         down_read(&dev_replace->rwsem);
 584         /* was the operation canceled, or is it finished? */
 585         if (dev_replace->replace_state !=
 586             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 587                 up_read(&dev_replace->rwsem);
 588                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 589                 return 0;
 590         }
 591
 592         tgt_device = dev_replace->tgtdev;
 593         src_device = dev_replace->srcdev;
 594         up_read(&dev_replace->rwsem);
 595
 596         /*
 597          * flush all outstanding I/O and inode extent mappings before the
 598          * copy operation is declared as being finished
 599          */
 600         ret = btrfs_start_delalloc_roots(fs_info, -1);
 601         if (ret) {
 602                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 603                 return ret;
 604         }
 605         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 606
 607         /*
 608          * We have to use this loop approach because at this point src_device
 609          * has to be available for transaction commit to complete, yet new
 610          * chunks shouldn't be allocated on the device.
 611          */
 612         while (1) {
 613                 trans = btrfs_start_transaction(root, 0);
 614                 if (IS_ERR(trans)) {
 615                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 616                         return PTR_ERR(trans);
 617                 }
 618                 ret = btrfs_commit_transaction(trans);
 619                 WARN_ON(ret);
 620
 621                 /* Prevent write_all_supers() during the finishing procedure */
 622                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
 623                 /* Prevent new chunks being allocated on the source device */
 624                 mutex_lock(&fs_info->chunk_mutex);
 625
 626                 if (!list_empty(&src_device->post_commit_list)) {
 627                         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 628                         mutex_unlock(&fs_info->chunk_mutex);
 629                 } else {
 630                         break;
 631                 }
 632         }
 633
 634         down_write(&dev_replace->rwsem);
 635         dev_replace->replace_state =
 636                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 637                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 638         dev_replace->tgtdev = NULL;
 639         dev_replace->srcdev = NULL;
 640         dev_replace->time_stopped = ktime_get_real_seconds();
 641         dev_replace->item_needs_writeback = 1;
 642
 643         /* replace old device with new one in mapping tree */
 644         if (!scrub_ret) {
 645                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 646                                                                 src_device,
 647                                                                 tgt_device);
 648         } else {
 649                 if (scrub_ret != -ECANCELED)
 650                         btrfs_err_in_rcu(fs_info,
 651                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 652                                  btrfs_dev_name(src_device),
 653                                  src_device->devid,
 654                                  rcu_str_deref(tgt_device->name), scrub_ret);
 655                 up_write(&dev_replace->rwsem);
 656                 mutex_unlock(&fs_info->chunk_mutex);
 657                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 658                 btrfs_rm_dev_replace_blocked(fs_info);
 659                 if (tgt_device)
 660                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 661                 btrfs_rm_dev_replace_unblocked(fs_info);
 662                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 663
 664                 return scrub_ret;
 665         }
 666
 667         btrfs_info_in_rcu(fs_info,
 668                           "dev_replace from %s (devid %llu) to %s finished",
 669                           btrfs_dev_name(src_device),
 670                           src_device->devid,
 671                           rcu_str_deref(tgt_device->name));
 672         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 673         tgt_device->devid = src_device->devid;
 674         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 675         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 676         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 677         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 678         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 679         btrfs_device_set_disk_total_bytes(tgt_device,
 680                                           src_device->disk_total_bytes);
 681         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 682         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
 683         tgt_device->commit_bytes_used = src_device->bytes_used;
 684
 685         btrfs_assign_next_active_device(src_device, tgt_device);
 686
 687         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 688         fs_info->fs_devices->rw_devices++;
 689
 690         up_write(&dev_replace->rwsem);
 691         btrfs_rm_dev_replace_blocked(fs_info);
 692
 693         btrfs_rm_dev_replace_remove_srcdev(src_device);
 694
 695         btrfs_rm_dev_replace_unblocked(fs_info);
 696
 697         /*
 698          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
 699          * update on-disk dev stats value during commit transaction
 700          */
 701         atomic_inc(&tgt_device->dev_stats_ccnt);
 702
 703         /*
 704          * this is again a consistent state where no dev_replace procedure
 705          * is running, the target device is part of the filesystem, the
 706          * source device is not part of the filesystem anymore and its 1st
 707          * superblock is scratched out so that it is no longer marked to
 708          * belong to this filesystem.
 709          */
 710         mutex_unlock(&fs_info->chunk_mutex);
 711         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 712
 713         /* replace the sysfs entry */
 714         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
 715         btrfs_rm_dev_replace_free_srcdev(src_device);
 716
 717         /* write back the superblocks */
 718         trans = btrfs_start_transaction(root, 0);
 719         if (!IS_ERR(trans))
 720                 btrfs_commit_transaction(trans);
 721
 722         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 723
 724         return 0;
 725 }
 726
 727 static void btrfs_dev_replace_update_device_in_mapping_tree(
 728                                                 struct btrfs_fs_info *fs_info,
 729                                                 struct btrfs_device *srcdev,
 730                                                 struct btrfs_device *tgtdev)
 731 {
 732         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 733         struct extent_map *em;
 734         struct map_lookup *map;
 735         u64 start = 0;
 736         int i;
 737
 738         write_lock(&em_tree->lock);
 739         do {
 740                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 741                 if (!em)
 742                         break;
 743                 map = em->map_lookup;
 744                 for (i = 0; i < map->num_stripes; i++)
 745                         if (srcdev == map->stripes[i].dev)
 746                                 map->stripes[i].dev = tgtdev;
 747                 start = em->start + em->len;
 748                 free_extent_map(em);
 749         } while (start);
 750         write_unlock(&em_tree->lock);
 751 }
 752
 753 /*
 754  * Read progress of device replace status according to the state and last
 755  * stored position. The value format is the same as for
 756  * btrfs_dev_replace::progress_1000
 757  */
 758 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
 759 {
 760         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 761         u64 ret = 0;
 762
 763         switch (dev_replace->replace_state) {
 764         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 765         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 766                 ret = 0;
 767                 break;
 768         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 769                 ret = 1000;
 770                 break;
 771         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 772         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 773                 ret = div64_u64(dev_replace->cursor_left,
 774                                 div_u64(btrfs_device_get_total_bytes(
 775                                                 dev_replace->srcdev), 1000));
 776                 break;
 777         }
 778
 779         return ret;
 780 }
 781
 782 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 783                               struct btrfs_ioctl_dev_replace_args *args)
 784 {
 785         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 786
 787         down_read(&dev_replace->rwsem);
 788         /* even if !dev_replace_is_valid, the values are good enough for
 789          * the replace_status ioctl */
 790         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 791         args->status.replace_state = dev_replace->replace_state;
 792         args->status.time_started = dev_replace->time_started;
 793         args->status.time_stopped = dev_replace->time_stopped;
 794         args->status.num_write_errors =
 795                 atomic64_read(&dev_replace->num_write_errors);
 796         args->status.num_uncorrectable_read_errors =
 797                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 798         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
 799         up_read(&dev_replace->rwsem);
 800 }
 801
 802 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 803 {
 804         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 805         struct btrfs_device *tgt_device = NULL;
 806         struct btrfs_device *src_device = NULL;
 807         struct btrfs_trans_handle *trans;
 808         struct btrfs_root *root = fs_info->tree_root;
 809         int result;
 810         int ret;
 811
 812         if (sb_rdonly(fs_info->sb))
 813                 return -EROFS;
 814
 815         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 816         down_write(&dev_replace->rwsem);
 817         switch (dev_replace->replace_state) {
 818         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 819         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 820         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 821                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 822                 up_write(&dev_replace->rwsem);
 823                 break;
 824         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 825                 tgt_device = dev_replace->tgtdev;
 826                 src_device = dev_replace->srcdev;
 827                 up_write(&dev_replace->rwsem);
 828                 ret = btrfs_scrub_cancel(fs_info);
 829                 if (ret < 0) {
 830                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 831                 } else {
 832                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 833                         /*
 834                          * btrfs_dev_replace_finishing() will handle the
 835                          * cleanup part
 836                          */
 837                         btrfs_info_in_rcu(fs_info,
 838                                 "dev_replace from %s (devid %llu) to %s canceled",
 839                                 btrfs_dev_name(src_device), src_device->devid,
 840                                 btrfs_dev_name(tgt_device));
 841                 }
 842                 break;
 843         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 844                 /*
 845                  * Scrub doing the replace isn't running so we need to do the
 846                  * cleanup step of btrfs_dev_replace_finishing() here
 847                  */
 848                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 849                 tgt_device = dev_replace->tgtdev;
 850                 src_device = dev_replace->srcdev;
 851                 dev_replace->tgtdev = NULL;
 852                 dev_replace->srcdev = NULL;
 853                 dev_replace->replace_state =
 854                                 BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 855                 dev_replace->time_stopped = ktime_get_real_seconds();
 856                 dev_replace->item_needs_writeback = 1;
 857
 858                 up_write(&dev_replace->rwsem);
 859
 860                 /* Scrub for replace must not be running in suspended state */
 861                 ret = btrfs_scrub_cancel(fs_info);
 862                 ASSERT(ret != -ENOTCONN);
 863
 864                 trans = btrfs_start_transaction(root, 0);
 865                 if (IS_ERR(trans)) {
 866                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 867                         return PTR_ERR(trans);
 868                 }
 869                 ret = btrfs_commit_transaction(trans);
 870                 WARN_ON(ret);
 871
 872                 btrfs_info_in_rcu(fs_info,
 873                 "suspended dev_replace from %s (devid %llu) to %s canceled",
 874                         btrfs_dev_name(src_device), src_device->devid,
 875                         btrfs_dev_name(tgt_device));
 876
 877                 if (tgt_device)
 878                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 879                 break;
 880         default:
 881                 up_write(&dev_replace->rwsem);
 882                 result = -EINVAL;
 883         }
 884
 885         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 886         return result;
 887 }
 888
 889 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 890 {
 891         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 892
 893         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 894         down_write(&dev_replace->rwsem);
 895
 896         switch (dev_replace->replace_state) {
 897         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 898         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 899         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 900         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 901                 break;
 902         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 903                 dev_replace->replace_state =
 904                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 905                 dev_replace->time_stopped = ktime_get_real_seconds();
 906                 dev_replace->item_needs_writeback = 1;
 907                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 908                 break;
 909         }
 910
 911         up_write(&dev_replace->rwsem);
 912         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 913 }
 914
 915 /* resume dev_replace procedure that was interrupted by unmount */
 916 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 917 {
 918         struct task_struct *task;
 919         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 920
 921         down_write(&dev_replace->rwsem);
 922
 923         switch (dev_replace->replace_state) {
 924         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 925         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 926         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 927                 up_write(&dev_replace->rwsem);
 928                 return 0;
 929         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 930                 break;
 931         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 932                 dev_replace->replace_state =
 933                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 934                 break;
 935         }
 936         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 937                 btrfs_info(fs_info,
 938                            "cannot continue dev_replace, tgtdev is missing");
 939                 btrfs_info(fs_info,
 940                            "you may cancel the operation after 'mount -o degraded'");
 941                 dev_replace->replace_state =
 942                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 943                 up_write(&dev_replace->rwsem);
 944                 return 0;
 945         }
 946         up_write(&dev_replace->rwsem);
 947
 948         /*
 949          * This could collide with a paused balance, but the exclusive op logic
 950          * should never allow both to start and pause. We don't want to allow
 951          * dev-replace to start anyway.
 952          */
 953         if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
 954                 down_write(&dev_replace->rwsem);
 955                 dev_replace->replace_state =
 956                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 957                 up_write(&dev_replace->rwsem);
 958                 btrfs_info(fs_info,
 959                 "cannot resume dev-replace, other exclusive operation running");
 960                 return 0;
 961         }
 962
 963         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 964         return PTR_ERR_OR_ZERO(task);
 965 }
 966
 967 static int btrfs_dev_replace_kthread(void *data)
 968 {
 969         struct btrfs_fs_info *fs_info = data;
 970         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 971         u64 progress;
 972         int ret;
 973
 974         progress = btrfs_dev_replace_progress(fs_info);
 975         progress = div_u64(progress, 10);
 976         btrfs_info_in_rcu(fs_info,
 977                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
 978                 btrfs_dev_name(dev_replace->srcdev),
 979                 dev_replace->srcdev->devid,
 980                 btrfs_dev_name(dev_replace->tgtdev),
 981                 (unsigned int)progress);
 982
 983         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 984                               dev_replace->committed_cursor_left,
 985                               btrfs_device_get_total_bytes(dev_replace->srcdev),
 986                               &dev_replace->scrub_progress, 0, 1);
 987         ret = btrfs_dev_replace_finishing(fs_info, ret);
 988         WARN_ON(ret && ret != -ECANCELED);
 989
 990         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
 991         return 0;
 992 }
 993
 994 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 995 {
 996         if (!dev_replace->is_valid)
 997                 return 0;
 998
 999         switch (dev_replace->replace_state) {
1000         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1001         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1002         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1003                 return 0;
1004         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1005         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1006                 /*
1007                  * return true even if tgtdev is missing (this is
1008                  * something that can happen if the dev_replace
1009                  * procedure is suspended by an umount and then
1010                  * the tgtdev is missing (or "btrfs dev scan") was
1011                  * not called and the filesystem is remounted
1012                  * in degraded state. This does not stop the
1013                  * dev_replace procedure. It needs to be canceled
1014                  * manually if the cancellation is wanted.
1015                  */
1016                 break;
1017         }
1018         return 1;
1019 }
1020
1021 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
1022 {
1023         percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1024 }
1025
1026 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1027 {
1028         percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1029         cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1030 }
1031
1032 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1033 {
1034         while (1) {
1035                 percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1036                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1037                                      &fs_info->fs_state)))
1038                         break;
1039
1040                 btrfs_bio_counter_dec(fs_info);
1041                 wait_event(fs_info->dev_replace.replace_wait,
1042                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1043                                      &fs_info->fs_state));
1044         }
1045 }