root/fs/btrfs/dev-replace.c

DEFINITIONS

1. btrfs_init_dev_replace
2. btrfs_init_dev_replace_tgtdev
3. btrfs_run_dev_replace
4. btrfs_dev_name
5. btrfs_dev_replace_start
6. btrfs_dev_replace_by_ioctl
7. btrfs_rm_dev_replace_blocked
8. btrfs_rm_dev_replace_unblocked
9. btrfs_dev_replace_finishing
10. btrfs_dev_replace_update_device_in_mapping_tree
11. btrfs_dev_replace_progress
12. btrfs_dev_replace_status
13. btrfs_dev_replace_cancel
14. btrfs_dev_replace_suspend_for_unmount
15. btrfs_resume_dev_replace_async
16. btrfs_dev_replace_kthread
17. btrfs_dev_replace_is_ongoing
18. btrfs_bio_counter_inc_noblocked
19. btrfs_bio_counter_sub
20. btrfs_bio_counter_inc_blocked

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STRATO AG 2012.  All rights reserved.
   4  */
   5 
   6 #include <linux/sched.h>
   7 #include <linux/bio.h>
   8 #include <linux/slab.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/kthread.h>
  11 #include <linux/math64.h>
  12 #include "misc.h"
  13 #include "ctree.h"
  14 #include "extent_map.h"
  15 #include "disk-io.h"
  16 #include "transaction.h"
  17 #include "print-tree.h"
  18 #include "volumes.h"
  19 #include "async-thread.h"
  20 #include "check-integrity.h"
  21 #include "rcu-string.h"
  22 #include "dev-replace.h"
  23 #include "sysfs.h"
  24 
  25 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
  26                                        int scrub_ret);
  27 static void btrfs_dev_replace_update_device_in_mapping_tree(
  28                                                 struct btrfs_fs_info *fs_info,
  29                                                 struct btrfs_device *srcdev,
  30                                                 struct btrfs_device *tgtdev);
  31 static int btrfs_dev_replace_kthread(void *data);
  32 
  33 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  34 {
  35         struct btrfs_key key;
  36         struct btrfs_root *dev_root = fs_info->dev_root;
  37         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  38         struct extent_buffer *eb;
  39         int slot;
  40         int ret = 0;
  41         struct btrfs_path *path = NULL;
  42         int item_size;
  43         struct btrfs_dev_replace_item *ptr;
  44         u64 src_devid;
  45 
  46         path = btrfs_alloc_path();
  47         if (!path) {
  48                 ret = -ENOMEM;
  49                 goto out;
  50         }
  51 
  52         key.objectid = 0;
  53         key.type = BTRFS_DEV_REPLACE_KEY;
  54         key.offset = 0;
  55         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  56         if (ret) {
  57 no_valid_dev_replace_entry_found:
  58                 ret = 0;
  59                 dev_replace->replace_state =
  60                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
  61                 dev_replace->cont_reading_from_srcdev_mode =
  62                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
  63                 dev_replace->time_started = 0;
  64                 dev_replace->time_stopped = 0;
  65                 atomic64_set(&dev_replace->num_write_errors, 0);
  66                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
  67                 dev_replace->cursor_left = 0;
  68                 dev_replace->committed_cursor_left = 0;
  69                 dev_replace->cursor_left_last_write_of_item = 0;
  70                 dev_replace->cursor_right = 0;
  71                 dev_replace->srcdev = NULL;
  72                 dev_replace->tgtdev = NULL;
  73                 dev_replace->is_valid = 0;
  74                 dev_replace->item_needs_writeback = 0;
  75                 goto out;
  76         }
  77         slot = path->slots[0];
  78         eb = path->nodes[0];
  79         item_size = btrfs_item_size_nr(eb, slot);
  80         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
  81 
  82         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
  83                 btrfs_warn(fs_info,
  84                         "dev_replace entry found has unexpected size, ignore entry");
  85                 goto no_valid_dev_replace_entry_found;
  86         }
  87 
  88         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
  89         dev_replace->cont_reading_from_srcdev_mode =
  90                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
  91         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
  92         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
  93         dev_replace->time_stopped =
  94                 btrfs_dev_replace_time_stopped(eb, ptr);
  95         atomic64_set(&dev_replace->num_write_errors,
  96                      btrfs_dev_replace_num_write_errors(eb, ptr));
  97         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
  98                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
  99         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 100         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 101         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 102         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 103         dev_replace->is_valid = 1;
 104 
 105         dev_replace->item_needs_writeback = 0;
 106         switch (dev_replace->replace_state) {
 107         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 108         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 109         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 110                 dev_replace->srcdev = NULL;
 111                 dev_replace->tgtdev = NULL;
 112                 break;
 113         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 114         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 115                 dev_replace->srcdev = btrfs_find_device(fs_info->fs_devices,
 116                                                 src_devid, NULL, NULL, true);
 117                 dev_replace->tgtdev = btrfs_find_device(fs_info->fs_devices,
 118                                                         BTRFS_DEV_REPLACE_DEVID,
 119                                                         NULL, NULL, true);
 120                 /*
 121                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 122                  * missing
 123                  */
 124                 if (!dev_replace->srcdev &&
 125                     !btrfs_test_opt(fs_info, DEGRADED)) {
 126                         ret = -EIO;
 127                         btrfs_warn(fs_info,
 128                            "cannot mount because device replace operation is ongoing and");
 129                         btrfs_warn(fs_info,
 130                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 131                            src_devid);
 132                 }
 133                 if (!dev_replace->tgtdev &&
 134                     !btrfs_test_opt(fs_info, DEGRADED)) {
 135                         ret = -EIO;
 136                         btrfs_warn(fs_info,
 137                            "cannot mount because device replace operation is ongoing and");
 138                         btrfs_warn(fs_info,
 139                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 140                                 BTRFS_DEV_REPLACE_DEVID);
 141                 }
 142                 if (dev_replace->tgtdev) {
 143                         if (dev_replace->srcdev) {
 144                                 dev_replace->tgtdev->total_bytes =
 145                                         dev_replace->srcdev->total_bytes;
 146                                 dev_replace->tgtdev->disk_total_bytes =
 147                                         dev_replace->srcdev->disk_total_bytes;
 148                                 dev_replace->tgtdev->commit_total_bytes =
 149                                         dev_replace->srcdev->commit_total_bytes;
 150                                 dev_replace->tgtdev->bytes_used =
 151                                         dev_replace->srcdev->bytes_used;
 152                                 dev_replace->tgtdev->commit_bytes_used =
 153                                         dev_replace->srcdev->commit_bytes_used;
 154                         }
 155                         set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
 156                                 &dev_replace->tgtdev->dev_state);
 157 
 158                         WARN_ON(fs_info->fs_devices->rw_devices == 0);
 159                         dev_replace->tgtdev->io_width = fs_info->sectorsize;
 160                         dev_replace->tgtdev->io_align = fs_info->sectorsize;
 161                         dev_replace->tgtdev->sector_size = fs_info->sectorsize;
 162                         dev_replace->tgtdev->fs_info = fs_info;
 163                         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
 164                                 &dev_replace->tgtdev->dev_state);
 165                 }
 166                 break;
 167         }
 168 
 169 out:
 170         btrfs_free_path(path);
 171         return ret;
 172 }
 173 
 174 /*
 175  * Initialize a new device for device replace target from a given source dev
 176  * and path.
 177  *
 178  * Return 0 and new device in @device_out, otherwise return < 0
 179  */
 180 static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 181                                   const char *device_path,
 182                                   struct btrfs_device *srcdev,
 183                                   struct btrfs_device **device_out)
 184 {
 185         struct btrfs_device *device;
 186         struct block_device *bdev;
 187         struct list_head *devices;
 188         struct rcu_string *name;
 189         u64 devid = BTRFS_DEV_REPLACE_DEVID;
 190         int ret = 0;
 191 
 192         *device_out = NULL;
 193         if (fs_info->fs_devices->seeding) {
 194                 btrfs_err(fs_info, "the filesystem is a seed filesystem!");
 195                 return -EINVAL;
 196         }
 197 
 198         bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
 199                                   fs_info->bdev_holder);
 200         if (IS_ERR(bdev)) {
 201                 btrfs_err(fs_info, "target device %s is invalid!", device_path);
 202                 return PTR_ERR(bdev);
 203         }
 204 
 205         sync_blockdev(bdev);
 206 
 207         devices = &fs_info->fs_devices->devices;
 208         list_for_each_entry(device, devices, dev_list) {
 209                 if (device->bdev == bdev) {
 210                         btrfs_err(fs_info,
 211                                   "target device is in the filesystem!");
 212                         ret = -EEXIST;
 213                         goto error;
 214                 }
 215         }
 216 
 217 
 218         if (i_size_read(bdev->bd_inode) <
 219             btrfs_device_get_total_bytes(srcdev)) {
 220                 btrfs_err(fs_info,
 221                           "target device is smaller than source device!");
 222                 ret = -EINVAL;
 223                 goto error;
 224         }
 225 
 226 
 227         device = btrfs_alloc_device(NULL, &devid, NULL);
 228         if (IS_ERR(device)) {
 229                 ret = PTR_ERR(device);
 230                 goto error;
 231         }
 232 
 233         name = rcu_string_strdup(device_path, GFP_KERNEL);
 234         if (!name) {
 235                 btrfs_free_device(device);
 236                 ret = -ENOMEM;
 237                 goto error;
 238         }
 239         rcu_assign_pointer(device->name, name);
 240 
 241         set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
 242         device->generation = 0;
 243         device->io_width = fs_info->sectorsize;
 244         device->io_align = fs_info->sectorsize;
 245         device->sector_size = fs_info->sectorsize;
 246         device->total_bytes = btrfs_device_get_total_bytes(srcdev);
 247         device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
 248         device->bytes_used = btrfs_device_get_bytes_used(srcdev);
 249         device->commit_total_bytes = srcdev->commit_total_bytes;
 250         device->commit_bytes_used = device->bytes_used;
 251         device->fs_info = fs_info;
 252         device->bdev = bdev;
 253         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 254         set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 255         device->mode = FMODE_EXCL;
 256         device->dev_stats_valid = 1;
 257         set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
 258         device->fs_devices = fs_info->fs_devices;
 259 
 260         mutex_lock(&fs_info->fs_devices->device_list_mutex);
 261         list_add(&device->dev_list, &fs_info->fs_devices->devices);
 262         fs_info->fs_devices->num_devices++;
 263         fs_info->fs_devices->open_devices++;
 264         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 265 
 266         *device_out = device;
 267         return 0;
 268 
 269 error:
 270         blkdev_put(bdev, FMODE_EXCL);
 271         return ret;
 272 }
 273 
 274 /*
 275  * called from commit_transaction. Writes changed device replace state to
 276  * disk.
 277  */
 278 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans)
 279 {
 280         struct btrfs_fs_info *fs_info = trans->fs_info;
 281         int ret;
 282         struct btrfs_root *dev_root = fs_info->dev_root;
 283         struct btrfs_path *path;
 284         struct btrfs_key key;
 285         struct extent_buffer *eb;
 286         struct btrfs_dev_replace_item *ptr;
 287         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 288 
 289         down_read(&dev_replace->rwsem);
 290         if (!dev_replace->is_valid ||
 291             !dev_replace->item_needs_writeback) {
 292                 up_read(&dev_replace->rwsem);
 293                 return 0;
 294         }
 295         up_read(&dev_replace->rwsem);
 296 
 297         key.objectid = 0;
 298         key.type = BTRFS_DEV_REPLACE_KEY;
 299         key.offset = 0;
 300 
 301         path = btrfs_alloc_path();
 302         if (!path) {
 303                 ret = -ENOMEM;
 304                 goto out;
 305         }
 306         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 307         if (ret < 0) {
 308                 btrfs_warn(fs_info,
 309                            "error %d while searching for dev_replace item!",
 310                            ret);
 311                 goto out;
 312         }
 313 
 314         if (ret == 0 &&
 315             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 316                 /*
 317                  * need to delete old one and insert a new one.
 318                  * Since no attempt is made to recover any old state, if the
 319                  * dev_replace state is 'running', the data on the target
 320                  * drive is lost.
 321                  * It would be possible to recover the state: just make sure
 322                  * that the beginning of the item is never changed and always
 323                  * contains all the essential information. Then read this
 324                  * minimal set of information and use it as a base for the
 325                  * new state.
 326                  */
 327                 ret = btrfs_del_item(trans, dev_root, path);
 328                 if (ret != 0) {
 329                         btrfs_warn(fs_info,
 330                                    "delete too small dev_replace item failed %d!",
 331                                    ret);
 332                         goto out;
 333                 }
 334                 ret = 1;
 335         }
 336 
 337         if (ret == 1) {
 338                 /* need to insert a new item */
 339                 btrfs_release_path(path);
 340                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 341                                               &key, sizeof(*ptr));
 342                 if (ret < 0) {
 343                         btrfs_warn(fs_info,
 344                                    "insert dev_replace item failed %d!", ret);
 345                         goto out;
 346                 }
 347         }
 348 
 349         eb = path->nodes[0];
 350         ptr = btrfs_item_ptr(eb, path->slots[0],
 351                              struct btrfs_dev_replace_item);
 352 
 353         down_write(&dev_replace->rwsem);
 354         if (dev_replace->srcdev)
 355                 btrfs_set_dev_replace_src_devid(eb, ptr,
 356                         dev_replace->srcdev->devid);
 357         else
 358                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 359         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 360                 dev_replace->cont_reading_from_srcdev_mode);
 361         btrfs_set_dev_replace_replace_state(eb, ptr,
 362                 dev_replace->replace_state);
 363         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 364         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 365         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 366                 atomic64_read(&dev_replace->num_write_errors));
 367         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 368                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 369         dev_replace->cursor_left_last_write_of_item =
 370                 dev_replace->cursor_left;
 371         btrfs_set_dev_replace_cursor_left(eb, ptr,
 372                 dev_replace->cursor_left_last_write_of_item);
 373         btrfs_set_dev_replace_cursor_right(eb, ptr,
 374                 dev_replace->cursor_right);
 375         dev_replace->item_needs_writeback = 0;
 376         up_write(&dev_replace->rwsem);
 377 
 378         btrfs_mark_buffer_dirty(eb);
 379 
 380 out:
 381         btrfs_free_path(path);
 382 
 383         return ret;
 384 }
 385 
 386 static char* btrfs_dev_name(struct btrfs_device *device)
 387 {
 388         if (!device || test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
 389                 return "<missing disk>";
 390         else
 391                 return rcu_str_deref(device->name);
 392 }
 393 
 394 static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 395                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
 396                 int read_src)
 397 {
 398         struct btrfs_root *root = fs_info->dev_root;
 399         struct btrfs_trans_handle *trans;
 400         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 401         int ret;
 402         struct btrfs_device *tgt_device = NULL;
 403         struct btrfs_device *src_device = NULL;
 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         /*
 418          * Here we commit the transaction to make sure commit_total_bytes
 419          * of all the devices are updated.
 420          */
 421         trans = btrfs_attach_transaction(root);
 422         if (!IS_ERR(trans)) {
 423                 ret = btrfs_commit_transaction(trans);
 424                 if (ret)
 425                         return ret;
 426         } else if (PTR_ERR(trans) != -ENOENT) {
 427                 return PTR_ERR(trans);
 428         }
 429 
 430         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 431                                             src_device, &tgt_device);
 432         if (ret)
 433                 return ret;
 434 
 435         down_write(&dev_replace->rwsem);
 436         switch (dev_replace->replace_state) {
 437         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 438         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 439         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 440                 break;
 441         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 442         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 443                 ASSERT(0);
 444                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 445                 up_write(&dev_replace->rwsem);
 446                 goto leave;
 447         }
 448 
 449         dev_replace->cont_reading_from_srcdev_mode = read_src;
 450         dev_replace->srcdev = src_device;
 451         dev_replace->tgtdev = tgt_device;
 452 
 453         btrfs_info_in_rcu(fs_info,
 454                       "dev_replace from %s (devid %llu) to %s started",
 455                       btrfs_dev_name(src_device),
 456                       src_device->devid,
 457                       rcu_str_deref(tgt_device->name));
 458 
 459         /*
 460          * from now on, the writes to the srcdev are all duplicated to
 461          * go to the tgtdev as well (refer to btrfs_map_block()).
 462          */
 463         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 464         dev_replace->time_started = ktime_get_real_seconds();
 465         dev_replace->cursor_left = 0;
 466         dev_replace->committed_cursor_left = 0;
 467         dev_replace->cursor_left_last_write_of_item = 0;
 468         dev_replace->cursor_right = 0;
 469         dev_replace->is_valid = 1;
 470         dev_replace->item_needs_writeback = 1;
 471         atomic64_set(&dev_replace->num_write_errors, 0);
 472         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 473         up_write(&dev_replace->rwsem);
 474 
 475         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 476         if (ret)
 477                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 478 
 479         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 480 
 481         /* Commit dev_replace state and reserve 1 item for it. */
 482         trans = btrfs_start_transaction(root, 1);
 483         if (IS_ERR(trans)) {
 484                 ret = PTR_ERR(trans);
 485                 down_write(&dev_replace->rwsem);
 486                 dev_replace->replace_state =
 487                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 488                 dev_replace->srcdev = NULL;
 489                 dev_replace->tgtdev = NULL;
 490                 up_write(&dev_replace->rwsem);
 491                 goto leave;
 492         }
 493 
 494         ret = btrfs_commit_transaction(trans);
 495         WARN_ON(ret);
 496 
 497         /* the disk copy procedure reuses the scrub code */
 498         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 499                               btrfs_device_get_total_bytes(src_device),
 500                               &dev_replace->scrub_progress, 0, 1);
 501 
 502         ret = btrfs_dev_replace_finishing(fs_info, ret);
 503         if (ret == -EINPROGRESS) {
 504                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 505         } else if (ret != -ECANCELED) {
 506                 WARN_ON(ret);
 507         }
 508 
 509         return ret;
 510 
 511 leave:
 512         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 513         return ret;
 514 }
 515 
 516 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 517                             struct btrfs_ioctl_dev_replace_args *args)
 518 {
 519         int ret;
 520 
 521         switch (args->start.cont_reading_from_srcdev_mode) {
 522         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 523         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 524                 break;
 525         default:
 526                 return -EINVAL;
 527         }
 528 
 529         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 530             args->start.tgtdev_name[0] == '\0')
 531                 return -EINVAL;
 532 
 533         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 534                                         args->start.srcdevid,
 535                                         args->start.srcdev_name,
 536                                         args->start.cont_reading_from_srcdev_mode);
 537         args->result = ret;
 538         /* don't warn if EINPROGRESS, someone else might be running scrub */
 539         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS ||
 540             ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR)
 541                 return 0;
 542 
 543         return ret;
 544 }
 545 
 546 /*
 547  * blocked until all in-flight bios operations are finished.
 548  */
 549 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 550 {
 551         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 552         wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
 553                    &fs_info->dev_replace.bio_counter));
 554 }
 555 
 556 /*
 557  * we have removed target device, it is safe to allow new bios request.
 558  */
 559 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 560 {
 561         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 562         wake_up(&fs_info->dev_replace.replace_wait);
 563 }
 564 
 565 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 566                                        int scrub_ret)
 567 {
 568         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 569         struct btrfs_device *tgt_device;
 570         struct btrfs_device *src_device;
 571         struct btrfs_root *root = fs_info->tree_root;
 572         u8 uuid_tmp[BTRFS_UUID_SIZE];
 573         struct btrfs_trans_handle *trans;
 574         int ret = 0;
 575 
 576         /* don't allow cancel or unmount to disturb the finishing procedure */
 577         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 578 
 579         down_read(&dev_replace->rwsem);
 580         /* was the operation canceled, or is it finished? */
 581         if (dev_replace->replace_state !=
 582             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 583                 up_read(&dev_replace->rwsem);
 584                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 585                 return 0;
 586         }
 587 
 588         tgt_device = dev_replace->tgtdev;
 589         src_device = dev_replace->srcdev;
 590         up_read(&dev_replace->rwsem);
 591 
 592         /*
 593          * flush all outstanding I/O and inode extent mappings before the
 594          * copy operation is declared as being finished
 595          */
 596         ret = btrfs_start_delalloc_roots(fs_info, -1);
 597         if (ret) {
 598                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 599                 return ret;
 600         }
 601         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 602 
 603         /*
 604          * We have to use this loop approach because at this point src_device
 605          * has to be available for transaction commit to complete, yet new
 606          * chunks shouldn't be allocated on the device.
 607          */
 608         while (1) {
 609                 trans = btrfs_start_transaction(root, 0);
 610                 if (IS_ERR(trans)) {
 611                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 612                         return PTR_ERR(trans);
 613                 }
 614                 ret = btrfs_commit_transaction(trans);
 615                 WARN_ON(ret);
 616 
 617                 /* Prevent write_all_supers() during the finishing procedure */
 618                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
 619                 /* Prevent new chunks being allocated on the source device */
 620                 mutex_lock(&fs_info->chunk_mutex);
 621 
 622                 if (!list_empty(&src_device->post_commit_list)) {
 623                         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 624                         mutex_unlock(&fs_info->chunk_mutex);
 625                 } else {
 626                         break;
 627                 }
 628         }
 629 
 630         down_write(&dev_replace->rwsem);
 631         dev_replace->replace_state =
 632                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 633                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 634         dev_replace->tgtdev = NULL;
 635         dev_replace->srcdev = NULL;
 636         dev_replace->time_stopped = ktime_get_real_seconds();
 637         dev_replace->item_needs_writeback = 1;
 638 
 639         /* replace old device with new one in mapping tree */
 640         if (!scrub_ret) {
 641                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 642                                                                 src_device,
 643                                                                 tgt_device);
 644         } else {
 645                 if (scrub_ret != -ECANCELED)
 646                         btrfs_err_in_rcu(fs_info,
 647                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 648                                  btrfs_dev_name(src_device),
 649                                  src_device->devid,
 650                                  rcu_str_deref(tgt_device->name), scrub_ret);
 651                 up_write(&dev_replace->rwsem);
 652                 mutex_unlock(&fs_info->chunk_mutex);
 653                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 654                 btrfs_rm_dev_replace_blocked(fs_info);
 655                 if (tgt_device)
 656                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 657                 btrfs_rm_dev_replace_unblocked(fs_info);
 658                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 659 
 660                 return scrub_ret;
 661         }
 662 
 663         btrfs_info_in_rcu(fs_info,
 664                           "dev_replace from %s (devid %llu) to %s finished",
 665                           btrfs_dev_name(src_device),
 666                           src_device->devid,
 667                           rcu_str_deref(tgt_device->name));
 668         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 669         tgt_device->devid = src_device->devid;
 670         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 671         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 672         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 673         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 674         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 675         btrfs_device_set_disk_total_bytes(tgt_device,
 676                                           src_device->disk_total_bytes);
 677         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 678         tgt_device->commit_bytes_used = src_device->bytes_used;
 679 
 680         btrfs_assign_next_active_device(src_device, tgt_device);
 681 
 682         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 683         fs_info->fs_devices->rw_devices++;
 684 
 685         up_write(&dev_replace->rwsem);
 686         btrfs_rm_dev_replace_blocked(fs_info);
 687 
 688         btrfs_rm_dev_replace_remove_srcdev(src_device);
 689 
 690         btrfs_rm_dev_replace_unblocked(fs_info);
 691 
 692         /*
 693          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
 694          * update on-disk dev stats value during commit transaction
 695          */
 696         atomic_inc(&tgt_device->dev_stats_ccnt);
 697 
 698         /*
 699          * this is again a consistent state where no dev_replace procedure
 700          * is running, the target device is part of the filesystem, the
 701          * source device is not part of the filesystem anymore and its 1st
 702          * superblock is scratched out so that it is no longer marked to
 703          * belong to this filesystem.
 704          */
 705         mutex_unlock(&fs_info->chunk_mutex);
 706         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 707 
 708         /* replace the sysfs entry */
 709         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
 710         btrfs_rm_dev_replace_free_srcdev(src_device);
 711 
 712         /* write back the superblocks */
 713         trans = btrfs_start_transaction(root, 0);
 714         if (!IS_ERR(trans))
 715                 btrfs_commit_transaction(trans);
 716 
 717         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 718 
 719         return 0;
 720 }
 721 
 722 static void btrfs_dev_replace_update_device_in_mapping_tree(
 723                                                 struct btrfs_fs_info *fs_info,
 724                                                 struct btrfs_device *srcdev,
 725                                                 struct btrfs_device *tgtdev)
 726 {
 727         struct extent_map_tree *em_tree = &fs_info->mapping_tree;
 728         struct extent_map *em;
 729         struct map_lookup *map;
 730         u64 start = 0;
 731         int i;
 732 
 733         write_lock(&em_tree->lock);
 734         do {
 735                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 736                 if (!em)
 737                         break;
 738                 map = em->map_lookup;
 739                 for (i = 0; i < map->num_stripes; i++)
 740                         if (srcdev == map->stripes[i].dev)
 741                                 map->stripes[i].dev = tgtdev;
 742                 start = em->start + em->len;
 743                 free_extent_map(em);
 744         } while (start);
 745         write_unlock(&em_tree->lock);
 746 }
 747 
 748 /*
 749  * Read progress of device replace status according to the state and last
 750  * stored position. The value format is the same as for
 751  * btrfs_dev_replace::progress_1000
 752  */
 753 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
 754 {
 755         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 756         u64 ret = 0;
 757 
 758         switch (dev_replace->replace_state) {
 759         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 760         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 761                 ret = 0;
 762                 break;
 763         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 764                 ret = 1000;
 765                 break;
 766         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 767         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 768                 ret = div64_u64(dev_replace->cursor_left,
 769                                 div_u64(btrfs_device_get_total_bytes(
 770                                                 dev_replace->srcdev), 1000));
 771                 break;
 772         }
 773 
 774         return ret;
 775 }
 776 
 777 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 778                               struct btrfs_ioctl_dev_replace_args *args)
 779 {
 780         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 781 
 782         down_read(&dev_replace->rwsem);
 783         /* even if !dev_replace_is_valid, the values are good enough for
 784          * the replace_status ioctl */
 785         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 786         args->status.replace_state = dev_replace->replace_state;
 787         args->status.time_started = dev_replace->time_started;
 788         args->status.time_stopped = dev_replace->time_stopped;
 789         args->status.num_write_errors =
 790                 atomic64_read(&dev_replace->num_write_errors);
 791         args->status.num_uncorrectable_read_errors =
 792                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 793         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
 794         up_read(&dev_replace->rwsem);
 795 }
 796 
 797 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 798 {
 799         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 800         struct btrfs_device *tgt_device = NULL;
 801         struct btrfs_device *src_device = NULL;
 802         struct btrfs_trans_handle *trans;
 803         struct btrfs_root *root = fs_info->tree_root;
 804         int result;
 805         int ret;
 806 
 807         if (sb_rdonly(fs_info->sb))
 808                 return -EROFS;
 809 
 810         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 811         down_write(&dev_replace->rwsem);
 812         switch (dev_replace->replace_state) {
 813         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 814         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 815         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 816                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 817                 up_write(&dev_replace->rwsem);
 818                 break;
 819         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 820                 tgt_device = dev_replace->tgtdev;
 821                 src_device = dev_replace->srcdev;
 822                 up_write(&dev_replace->rwsem);
 823                 ret = btrfs_scrub_cancel(fs_info);
 824                 if (ret < 0) {
 825                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 826                 } else {
 827                         result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 828                         /*
 829                          * btrfs_dev_replace_finishing() will handle the
 830                          * cleanup part
 831                          */
 832                         btrfs_info_in_rcu(fs_info,
 833                                 "dev_replace from %s (devid %llu) to %s canceled",
 834                                 btrfs_dev_name(src_device), src_device->devid,
 835                                 btrfs_dev_name(tgt_device));
 836                 }
 837                 break;
 838         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 839                 /*
 840                  * Scrub doing the replace isn't running so we need to do the
 841                  * cleanup step of btrfs_dev_replace_finishing() here
 842                  */
 843                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 844                 tgt_device = dev_replace->tgtdev;
 845                 src_device = dev_replace->srcdev;
 846                 dev_replace->tgtdev = NULL;
 847                 dev_replace->srcdev = NULL;
 848                 dev_replace->replace_state =
 849                                 BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 850                 dev_replace->time_stopped = ktime_get_real_seconds();
 851                 dev_replace->item_needs_writeback = 1;
 852 
 853                 up_write(&dev_replace->rwsem);
 854 
 855                 /* Scrub for replace must not be running in suspended state */
 856                 ret = btrfs_scrub_cancel(fs_info);
 857                 ASSERT(ret != -ENOTCONN);
 858 
 859                 trans = btrfs_start_transaction(root, 0);
 860                 if (IS_ERR(trans)) {
 861                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 862                         return PTR_ERR(trans);
 863                 }
 864                 ret = btrfs_commit_transaction(trans);
 865                 WARN_ON(ret);
 866 
 867                 btrfs_info_in_rcu(fs_info,
 868                 "suspended dev_replace from %s (devid %llu) to %s canceled",
 869                         btrfs_dev_name(src_device), src_device->devid,
 870                         btrfs_dev_name(tgt_device));
 871 
 872                 if (tgt_device)
 873                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
 874                 break;
 875         default:
 876                 up_write(&dev_replace->rwsem);
 877                 result = -EINVAL;
 878         }
 879 
 880         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 881         return result;
 882 }
 883 
 884 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 885 {
 886         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 887 
 888         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 889         down_write(&dev_replace->rwsem);
 890 
 891         switch (dev_replace->replace_state) {
 892         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 893         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 894         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 895         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 896                 break;
 897         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 898                 dev_replace->replace_state =
 899                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 900                 dev_replace->time_stopped = ktime_get_real_seconds();
 901                 dev_replace->item_needs_writeback = 1;
 902                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 903                 break;
 904         }
 905 
 906         up_write(&dev_replace->rwsem);
 907         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 908 }
 909 
 910 /* resume dev_replace procedure that was interrupted by unmount */
 911 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 912 {
 913         struct task_struct *task;
 914         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 915 
 916         down_write(&dev_replace->rwsem);
 917 
 918         switch (dev_replace->replace_state) {
 919         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 920         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 921         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 922                 up_write(&dev_replace->rwsem);
 923                 return 0;
 924         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 925                 break;
 926         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 927                 dev_replace->replace_state =
 928                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 929                 break;
 930         }
 931         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 932                 btrfs_info(fs_info,
 933                            "cannot continue dev_replace, tgtdev is missing");
 934                 btrfs_info(fs_info,
 935                            "you may cancel the operation after 'mount -o degraded'");
 936                 dev_replace->replace_state =
 937                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 938                 up_write(&dev_replace->rwsem);
 939                 return 0;
 940         }
 941         up_write(&dev_replace->rwsem);
 942 
 943         /*
 944          * This could collide with a paused balance, but the exclusive op logic
 945          * should never allow both to start and pause. We don't want to allow
 946          * dev-replace to start anyway.
 947          */
 948         if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
 949                 down_write(&dev_replace->rwsem);
 950                 dev_replace->replace_state =
 951                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 952                 up_write(&dev_replace->rwsem);
 953                 btrfs_info(fs_info,
 954                 "cannot resume dev-replace, other exclusive operation running");
 955                 return 0;
 956         }
 957 
 958         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 959         return PTR_ERR_OR_ZERO(task);
 960 }
 961 
 962 static int btrfs_dev_replace_kthread(void *data)
 963 {
 964         struct btrfs_fs_info *fs_info = data;
 965         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 966         u64 progress;
 967         int ret;
 968 
 969         progress = btrfs_dev_replace_progress(fs_info);
 970         progress = div_u64(progress, 10);
 971         btrfs_info_in_rcu(fs_info,
 972                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
 973                 btrfs_dev_name(dev_replace->srcdev),
 974                 dev_replace->srcdev->devid,
 975                 btrfs_dev_name(dev_replace->tgtdev),
 976                 (unsigned int)progress);
 977 
 978         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 979                               dev_replace->committed_cursor_left,
 980                               btrfs_device_get_total_bytes(dev_replace->srcdev),
 981                               &dev_replace->scrub_progress, 0, 1);
 982         ret = btrfs_dev_replace_finishing(fs_info, ret);
 983         WARN_ON(ret && ret != -ECANCELED);
 984 
 985         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
 986         return 0;
 987 }
 988 
 989 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 990 {
 991         if (!dev_replace->is_valid)
 992                 return 0;
 993 
 994         switch (dev_replace->replace_state) {
 995         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 996         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 997         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 998                 return 0;
 999         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1000         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1001                 /*
1002                  * return true even if tgtdev is missing (this is
1003                  * something that can happen if the dev_replace
1004                  * procedure is suspended by an umount and then
1005                  * the tgtdev is missing (or "btrfs dev scan") was
1006                  * not called and the filesystem is remounted
1007                  * in degraded state. This does not stop the
1008                  * dev_replace procedure. It needs to be canceled
1009                  * manually if the cancellation is wanted.
1010                  */
1011                 break;
1012         }
1013         return 1;
1014 }
1015 
1016 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
1017 {
1018         percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1019 }
1020 
1021 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1022 {
1023         percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1024         cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1025 }
1026 
1027 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1028 {
1029         while (1) {
1030                 percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1031                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1032                                      &fs_info->fs_state)))
1033                         break;
1034 
1035                 btrfs_bio_counter_dec(fs_info);
1036                 wait_event(fs_info->dev_replace.replace_wait,
1037                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1038                                      &fs_info->fs_state));
1039         }
1040 }