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
 404         src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,
 405                                                   srcdev_name);
 406         if (IS_ERR(src_device))
 407                 return PTR_ERR(src_device);
 408
 409         if (btrfs_pinned_by_swapfile(fs_info, src_device)) {
 410                 btrfs_warn_in_rcu(fs_info,
 411           "cannot replace device %s (devid %llu) due to active swapfile",
 412                         btrfs_dev_name(src_device), src_device->devid);
 413                 return -ETXTBSY;
 414         }
 415
 416         /*
 417          * Here we commit the transaction to make sure commit_total_bytes
 418          * of all the devices are updated.
 419          */
 420         trans = btrfs_attach_transaction(root);
 421         if (!IS_ERR(trans)) {
 422                 ret = btrfs_commit_transaction(trans);
 423                 if (ret)
 424                         return ret;
 425         } else if (PTR_ERR(trans) != -ENOENT) {
 426                 return PTR_ERR(trans);
 427         }
 428
 429         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 430                                             src_device, &tgt_device);
 431         if (ret)
 432                 return ret;
 433
 434         down_write(&dev_replace->rwsem);
 435         switch (dev_replace->replace_state) {
 436         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 437         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 438         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 439                 break;
 440         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 441         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 442                 ASSERT(0);
 443                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 444                 up_write(&dev_replace->rwsem);
 445                 goto leave;
 446         }
 447
 448         dev_replace->cont_reading_from_srcdev_mode = read_src;
 449         dev_replace->srcdev = src_device;
 450         dev_replace->tgtdev = tgt_device;
 451
 452         btrfs_info_in_rcu(fs_info,
 453                       "dev_replace from %s (devid %llu) to %s started",
 454                       btrfs_dev_name(src_device),
 455                       src_device->devid,
 456                       rcu_str_deref(tgt_device->name));
 457
 458         /*
 459          * from now on, the writes to the srcdev are all duplicated to
 460          * go to the tgtdev as well (refer to btrfs_map_block()).
 461          */
 462         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 463         dev_replace->time_started = ktime_get_real_seconds();
 464         dev_replace->cursor_left = 0;
 465         dev_replace->committed_cursor_left = 0;
 466         dev_replace->cursor_left_last_write_of_item = 0;
 467         dev_replace->cursor_right = 0;
 468         dev_replace->is_valid = 1;
 469         dev_replace->item_needs_writeback = 1;
 470         atomic64_set(&dev_replace->num_write_errors, 0);
 471         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 472         up_write(&dev_replace->rwsem);
 473
 474         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 475         if (ret)
 476                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 477
 478         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 479
 480         /* Commit dev_replace state and reserve 1 item for it. */
 481         trans = btrfs_start_transaction(root, 1);
 482         if (IS_ERR(trans)) {
 483                 ret = PTR_ERR(trans);
 484                 down_write(&dev_replace->rwsem);
 485                 dev_replace->replace_state =
 486                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 487                 dev_replace->srcdev = NULL;
 488                 dev_replace->tgtdev = NULL;
 489                 up_write(&dev_replace->rwsem);
 490                 goto leave;
 491         }
 492
 493         ret = btrfs_commit_transaction(trans);
 494         WARN_ON(ret);
 495
 496         /* the disk copy procedure reuses the scrub code */
 497         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 498                               btrfs_device_get_total_bytes(src_device),
 499                               &dev_replace->scrub_progress, 0, 1);
 500
 501         ret = btrfs_dev_replace_finishing(fs_info, ret);
 502         if (ret == -EINPROGRESS) {
 503                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 504         } else if (ret != -ECANCELED) {
 505                 WARN_ON(ret);
 506         }
 507
 508         return ret;
 509
 510 leave:
 511         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 512         return ret;
 513 }
 514
 515 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 516                             struct btrfs_ioctl_dev_replace_args *args)
 517 {
 518         int ret;
 519
 520         switch (args->start.cont_reading_from_srcdev_mode) {
 521         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 522         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 523                 break;
 524         default:
 525                 return -EINVAL;
 526         }
 527
 528         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 529             args->start.tgtdev_name[0] == '\0')
 530                 return -EINVAL;
 531
 532         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 533                                         args->start.srcdevid,
 534                                         args->start.srcdev_name,
 535                                         args->start.cont_reading_from_srcdev_mode);
 536         args->result = ret;
 537         /* don't warn if EINPROGRESS, someone else might be running scrub */
 538         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS ||
 539             ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR)
 540                 return 0;
 541
 542         return ret;
 543 }
 544
 545 /*
 546  * blocked until all in-flight bios operations are finished.
 547  */
 548 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 549 {
 550         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 551         wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
 552                    &fs_info->dev_replace.bio_counter));
 553 }
 554
 555 /*
 556  * we have removed target device, it is safe to allow new bios request.
 557  */
 558 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 559 {
 560         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 561         wake_up(&fs_info->dev_replace.replace_wait);
 562 }
 563
 564 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 565                                        int scrub_ret)
 566 {
 567         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 568         struct btrfs_device *tgt_device;
 569         struct btrfs_device *src_device;
 570         struct btrfs_root *root = fs_info->tree_root;
 571         u8 uuid_tmp[BTRFS_UUID_SIZE];
 572         struct btrfs_trans_handle *trans;
 573         int ret = 0;
 574
 575         /* don't allow cancel or unmount to disturb the finishing procedure */
 576         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 577
 578         down_read(&dev_replace->rwsem);
 579         /* was the operation canceled, or is it finished? */
 580         if (dev_replace->replace_state !=
 581             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 582                 up_read(&dev_replace->rwsem);
 583                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 584                 return 0;
 585         }
 586
 587         tgt_device = dev_replace->tgtdev;
 588         src_device = dev_replace->srcdev;
 589         up_read(&dev_replace->rwsem);
 590
 591         /*
 592          * flush all outstanding I/O and inode extent mappings before the
 593          * copy operation is declared as being finished
 594          */
 595         ret = btrfs_start_delalloc_roots(fs_info, -1);
 596         if (ret) {
 597                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 598                 return ret;
 599         }
 600         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 601
 602         /*
 603          * We have to use this loop approach because at this point src_device
 604          * has to be available for transaction commit to complete, yet new
 605          * chunks shouldn't be allocated on the device.
 606          */
 607         while (1) {
 608                 trans = btrfs_start_transaction(root, 0);
 609                 if (IS_ERR(trans)) {
 610                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 611                         return PTR_ERR(trans);
 612                 }
 613                 ret = btrfs_commit_transaction(trans);
 614                 WARN_ON(ret);
 615
 616                 /* Prevent write_all_supers() during the finishing procedure */
 617                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
 618                 /* Prevent new chunks being allocated on the source device */
 619                 mutex_lock(&fs_info->chunk_mutex);
 620
 621                 if (!list_empty(&src_device->post_commit_list)) {
 622                         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 623                         mutex_unlock(&fs_info->chunk_mutex);
 624                 } else {
 625                         break;
 626                 }
 627         }
 628
 629         down_write(&dev_replace->rwsem);
 630         dev_replace->replace_state =
 631                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 632                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 633         dev_replace->tgtdev = NULL;
 634         dev_replace->srcdev = NULL;
 635         dev_replace->time_stopped = ktime_get_real_seconds();
 636         dev_replace->item_needs_writeback = 1;
 637
 638         /* replace old device with new one in mapping tree */
 639         if (!scrub_ret) {
 640                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 641                                                                 src_device,
 642                                                                 tgt_device);
 643         } else {
 644                 if (scrub_ret != -ECANCELED)
 645                         btrfs_err_in_rcu(fs_info,
 646                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 647                                  btrfs_dev_name(src_device),
 648                                  src_device->devid,
 649                                  rcu_str_deref(tgt_device->name), scrub_ret);
 650                 up_write(&dev_replace->rwsem);
 651                 mutex_unlock(&fs_info->chunk_mutex);
 652                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 653                 btrfs_rm_dev_replace_blocked(fs_info);
 654                 if (tgt_device)
 655                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 656                 btrfs_rm_dev_replace_unblocked(fs_info);
 657                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 658
 659                 return scrub_ret;
 660         }
 661
 662         btrfs_info_in_rcu(fs_info,
 663                           "dev_replace from %s (devid %llu) to %s finished",
 664                           btrfs_dev_name(src_device),
 665                           src_device->devid,
 666                           rcu_str_deref(tgt_device->name));
 667         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 668         tgt_device->devid = src_device->devid;
 669         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 670         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 671         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 672         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 673         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 674         btrfs_device_set_disk_total_bytes(tgt_device,
 675                                           src_device->disk_total_bytes);
 676         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 677         tgt_device->commit_bytes_used = src_device->bytes_used;
 678
 679         btrfs_assign_next_active_device(src_device, tgt_device);
 680
 681         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 682         fs_info->fs_devices->rw_devices++;
 683
 684         up_write(&dev_replace->rwsem);
 685         btrfs_rm_dev_replace_blocked(fs_info);
 686
 687         btrfs_rm_dev_replace_remove_srcdev(src_device);
 688
 689         btrfs_rm_dev_replace_unblocked(fs_info);
 690
 691         /*
 692          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
 693          * update on-disk dev stats value during commit transaction
 694          */
 695         atomic_inc(&tgt_device->dev_stats_ccnt);
 696
 697         /*
 698          * this is again a consistent state where no dev_replace procedure
 699          * is running, the target device is part of the filesystem, the
 700          * source device is not part of the filesystem anymore and its 1st
 701          * superblock is scratched out so that it is no longer marked to
 702          * belong to this filesystem.
 703          */
 704         mutex_unlock(&fs_info->chunk_mutex);
 705         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 706
 707         /* replace the sysfs entry */
 708         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
 709         btrfs_rm_dev_replace_free_srcdev(src_device);
 710
 711         /* write back the superblocks */
 712         trans = btrfs_start_transaction(root, 0);
 713         if (!IS_ERR(trans))
 714                 btrfs_commit_transaction(trans);
 715
 716         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 717
 718         return 0;
 719 }
 720
 721 static void btrfs_dev_replace_update_device_in_mapping_tree(
 722                                                 struct btrfs_fs_info *fs_info,
 723                                                 struct btrfs_device *srcdev,
 724                                                 struct btrfs_device *tgtdev)
 725 {
 726         struct extent_map_tree *em_tree = &fs_info->mapping_tree;
 727         struct extent_map *em;
 728         struct map_lookup *map;
 729         u64 start = 0;
 730         int i;
 731
 732         write_lock(&em_tree->lock);
 733         do {
 734                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 735                 if (!em)
 736                         break;
 737                 map = em->map_lookup;
 738                 for (i = 0; i < map->num_stripes; i++)
 739                         if (srcdev == map->stripes[i].dev)
 740                                 map->stripes[i].dev = tgtdev;
 741                 start = em->start + em->len;
 742                 free_extent_map(em);
 743         } while (start);
 744         write_unlock(&em_tree->lock);
 745 }
 746
 747 /*
 748  * Read progress of device replace status according to the state and last
 749  * stored position. The value format is the same as for
 750  * btrfs_dev_replace::progress_1000
 751  */
 752 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
 753 {
 754         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 755         u64 ret = 0;
 756
 757         switch (dev_replace->replace_state) {
 758         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 759         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 760                 ret = 0;
 761                 break;
 762         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 763                 ret = 1000;
 764                 break;
 765         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 766         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 767                 ret = div64_u64(dev_replace->cursor_left,
 768                                 div_u64(btrfs_device_get_total_bytes(
 769                                                 dev_replace->srcdev), 1000));
 770                 break;
 771         }
 772
 773         return ret;
 774 }
 775
 776 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 777                               struct btrfs_ioctl_dev_replace_args *args)
 778 {
 779         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 780
 781         down_read(&dev_replace->rwsem);
 782         /* even if !dev_replace_is_valid, the values are good enough for
 783          * the replace_status ioctl */
 784         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 785         args->status.replace_state = dev_replace->replace_state;
 786         args->status.time_started = dev_replace->time_started;
 787         args->status.time_stopped = dev_replace->time_stopped;
 788         args->status.num_write_errors =
 789                 atomic64_read(&dev_replace->num_write_errors);
 790         args->status.num_uncorrectable_read_errors =
 791                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 792         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
 793         up_read(&dev_replace->rwsem);
 794 }
 795
 796 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 797 {
 798         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 799         struct btrfs_device *tgt_device = NULL;
 800         struct btrfs_device *src_device = NULL;
 801         struct btrfs_trans_handle *trans;
 802         struct btrfs_root *root = fs_info->tree_root;
 803         int result;
 804         int ret;
 805
 806         if (sb_rdonly(fs_info->sb))
 807                 return -EROFS;
 808
 809         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 810         down_write(&dev_replace->rwsem);
 811         switch (dev_replace->replace_state) {
 812         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 813         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 814         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 815                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 816                 up_write(&dev_replace->rwsem);
 817                 break;
 818         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 819                 tgt_device = dev_replace->tgtdev;
 820                 src_device = dev_replace->srcdev;
 821                 up_write(&dev_replace->rwsem);
 822                 ret = btrfs_scrub_cancel(fs_info);
 823                 if (ret < 0) {
 824                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 825                 } else {
 826                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 827                         /*
 828                          * btrfs_dev_replace_finishing() will handle the
 829                          * cleanup part
 830                          */
 831                         btrfs_info_in_rcu(fs_info,
 832                                 "dev_replace from %s (devid %llu) to %s canceled",
 833                                 btrfs_dev_name(src_device), src_device->devid,
 834                                 btrfs_dev_name(tgt_device));
 835                 }
 836                 break;
 837         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 838                 /*
 839                  * Scrub doing the replace isn't running so we need to do the
 840                  * cleanup step of btrfs_dev_replace_finishing() here
 841                  */
 842                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 843                 tgt_device = dev_replace->tgtdev;
 844                 src_device = dev_replace->srcdev;
 845                 dev_replace->tgtdev = NULL;
 846                 dev_replace->srcdev = NULL;
 847                 dev_replace->replace_state =
 848                                 BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 849                 dev_replace->time_stopped = ktime_get_real_seconds();
 850                 dev_replace->item_needs_writeback = 1;
 851
 852                 up_write(&dev_replace->rwsem);
 853
 854                 /* Scrub for replace must not be running in suspended state */
 855                 ret = btrfs_scrub_cancel(fs_info);
 856                 ASSERT(ret != -ENOTCONN);
 857
 858                 trans = btrfs_start_transaction(root, 0);
 859                 if (IS_ERR(trans)) {
 860                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 861                         return PTR_ERR(trans);
 862                 }
 863                 ret = btrfs_commit_transaction(trans);
 864                 WARN_ON(ret);
 865
 866                 btrfs_info_in_rcu(fs_info,
 867                 "suspended dev_replace from %s (devid %llu) to %s canceled",
 868                         btrfs_dev_name(src_device), src_device->devid,
 869                         btrfs_dev_name(tgt_device));
 870
 871                 if (tgt_device)
 872                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 873                 break;
 874         default:
 875                 up_write(&dev_replace->rwsem);
 876                 result = -EINVAL;
 877         }
 878
 879         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 880         return result;
 881 }
 882
 883 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 884 {
 885         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 886
 887         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 888         down_write(&dev_replace->rwsem);
 889
 890         switch (dev_replace->replace_state) {
 891         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 892         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 893         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 894         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 895                 break;
 896         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 897                 dev_replace->replace_state =
 898                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 899                 dev_replace->time_stopped = ktime_get_real_seconds();
 900                 dev_replace->item_needs_writeback = 1;
 901                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 902                 break;
 903         }
 904
 905         up_write(&dev_replace->rwsem);
 906         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 907 }
 908
 909 /* resume dev_replace procedure that was interrupted by unmount */
 910 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 911 {
 912         struct task_struct *task;
 913         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 914
 915         down_write(&dev_replace->rwsem);
 916
 917         switch (dev_replace->replace_state) {
 918         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 919         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 920         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 921                 up_write(&dev_replace->rwsem);
 922                 return 0;
 923         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 924                 break;
 925         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 926                 dev_replace->replace_state =
 927                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 928                 break;
 929         }
 930         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 931                 btrfs_info(fs_info,
 932                            "cannot continue dev_replace, tgtdev is missing");
 933                 btrfs_info(fs_info,
 934                            "you may cancel the operation after 'mount -o degraded'");
 935                 dev_replace->replace_state =
 936                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 937                 up_write(&dev_replace->rwsem);
 938                 return 0;
 939         }
 940         up_write(&dev_replace->rwsem);
 941
 942         /*
 943          * This could collide with a paused balance, but the exclusive op logic
 944          * should never allow both to start and pause. We don't want to allow
 945          * dev-replace to start anyway.
 946          */
 947         if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
 948                 down_write(&dev_replace->rwsem);
 949                 dev_replace->replace_state =
 950                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 951                 up_write(&dev_replace->rwsem);
 952                 btrfs_info(fs_info,
 953                 "cannot resume dev-replace, other exclusive operation running");
 954                 return 0;
 955         }
 956
 957         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 958         return PTR_ERR_OR_ZERO(task);
 959 }
 960
 961 static int btrfs_dev_replace_kthread(void *data)
 962 {
 963         struct btrfs_fs_info *fs_info = data;
 964         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 965         u64 progress;
 966         int ret;
 967
 968         progress = btrfs_dev_replace_progress(fs_info);
 969         progress = div_u64(progress, 10);
 970         btrfs_info_in_rcu(fs_info,
 971                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
 972                 btrfs_dev_name(dev_replace->srcdev),
 973                 dev_replace->srcdev->devid,
 974                 btrfs_dev_name(dev_replace->tgtdev),
 975                 (unsigned int)progress);
 976
 977         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 978                               dev_replace->committed_cursor_left,
 979                               btrfs_device_get_total_bytes(dev_replace->srcdev),
 980                               &dev_replace->scrub_progress, 0, 1);
 981         ret = btrfs_dev_replace_finishing(fs_info, ret);
 982         WARN_ON(ret && ret != -ECANCELED);
 983
 984         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
 985         return 0;
 986 }
 987
 988 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 989 {
 990         if (!dev_replace->is_valid)
 991                 return 0;
 992
 993         switch (dev_replace->replace_state) {
 994         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 995         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 996         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 997                 return 0;
 998         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 999         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1000                 /*
1001                  * return true even if tgtdev is missing (this is
1002                  * something that can happen if the dev_replace
1003                  * procedure is suspended by an umount and then
1004                  * the tgtdev is missing (or "btrfs dev scan") was
1005                  * not called and the filesystem is remounted
1006                  * in degraded state. This does not stop the
1007                  * dev_replace procedure. It needs to be canceled
1008                  * manually if the cancellation is wanted.
1009                  */
1010                 break;
1011         }
1012         return 1;
1013 }
1014
1015 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
1016 {
1017         percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1018 }
1019
1020 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1021 {
1022         percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1023         cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1024 }
1025
1026 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1027 {
1028         while (1) {
1029                 percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1030                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1031                                      &fs_info->fs_state)))
1032                         break;
1033
1034                 btrfs_bio_counter_dec(fs_info);
1035                 wait_event(fs_info->dev_replace.replace_wait,
1036                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1037                                      &fs_info->fs_state));
1038         }
1039 }