fs/btrfs/dev-replace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STRATO AG 2012.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/bio.h>
   8 #include <linux/slab.h>
   9 #include <linux/buffer_head.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/random.h>
  12 #include <linux/iocontext.h>
  13 #include <linux/capability.h>
  14 #include <linux/kthread.h>
  15 #include <linux/math64.h>
  16 #include <asm/div64.h>
  17 #include "ctree.h"
  18 #include "extent_map.h"
  19 #include "disk-io.h"
  20 #include "transaction.h"
  21 #include "print-tree.h"
  22 #include "volumes.h"
  23 #include "async-thread.h"
  24 #include "check-integrity.h"
  25 #include "rcu-string.h"
  26 #include "dev-replace.h"
  27 #include "sysfs.h"
  28
  29 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
  30                                        int scrub_ret);
  31 static void btrfs_dev_replace_update_device_in_mapping_tree(
  32                                                 struct btrfs_fs_info *fs_info,
  33                                                 struct btrfs_device *srcdev,
  34                                                 struct btrfs_device *tgtdev);
  35 static int btrfs_dev_replace_kthread(void *data);
  36
  37 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  38 {
  39         struct btrfs_key key;
  40         struct btrfs_root *dev_root = fs_info->dev_root;
  41         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  42         struct extent_buffer *eb;
  43         int slot;
  44         int ret = 0;
  45         struct btrfs_path *path = NULL;
  46         int item_size;
  47         struct btrfs_dev_replace_item *ptr;
  48         u64 src_devid;
  49
  50         path = btrfs_alloc_path();
  51         if (!path) {
  52                 ret = -ENOMEM;
  53                 goto out;
  54         }
  55
  56         key.objectid = 0;
  57         key.type = BTRFS_DEV_REPLACE_KEY;
  58         key.offset = 0;
  59         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  60         if (ret) {
  61 no_valid_dev_replace_entry_found:
  62                 ret = 0;
  63                 dev_replace->replace_state =
  64                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
  65                 dev_replace->cont_reading_from_srcdev_mode =
  66                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
  67                 dev_replace->replace_state = 0;
  68                 dev_replace->time_started = 0;
  69                 dev_replace->time_stopped = 0;
  70                 atomic64_set(&dev_replace->num_write_errors, 0);
  71                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
  72                 dev_replace->cursor_left = 0;
  73                 dev_replace->committed_cursor_left = 0;
  74                 dev_replace->cursor_left_last_write_of_item = 0;
  75                 dev_replace->cursor_right = 0;
  76                 dev_replace->srcdev = NULL;
  77                 dev_replace->tgtdev = NULL;
  78                 dev_replace->is_valid = 0;
  79                 dev_replace->item_needs_writeback = 0;
  80                 goto out;
  81         }
  82         slot = path->slots[0];
  83         eb = path->nodes[0];
  84         item_size = btrfs_item_size_nr(eb, slot);
  85         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
  86
  87         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
  88                 btrfs_warn(fs_info,
  89                         "dev_replace entry found has unexpected size, ignore entry");
  90                 goto no_valid_dev_replace_entry_found;
  91         }
  92
  93         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
  94         dev_replace->cont_reading_from_srcdev_mode =
  95                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
  96         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
  97         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
  98         dev_replace->time_stopped =
  99                 btrfs_dev_replace_time_stopped(eb, ptr);
 100         atomic64_set(&dev_replace->num_write_errors,
 101                      btrfs_dev_replace_num_write_errors(eb, ptr));
 102         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 103                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 104         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 105         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 106         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 107         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 108         dev_replace->is_valid = 1;
 109
 110         dev_replace->item_needs_writeback = 0;
 111         switch (dev_replace->replace_state) {
 112         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 113         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 114         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 115                 dev_replace->srcdev = NULL;
 116                 dev_replace->tgtdev = NULL;
 117                 break;
 118         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 119         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 120                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
 121                                                         NULL, NULL);
 122                 dev_replace->tgtdev = btrfs_find_device(fs_info,
 123                                                         BTRFS_DEV_REPLACE_DEVID,
 124                                                         NULL, NULL);
 125                 /*
 126                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 127                  * missing
 128                  */
 129                 if (!dev_replace->srcdev &&
 130                     !btrfs_test_opt(fs_info, DEGRADED)) {
 131                         ret = -EIO;
 132                         btrfs_warn(fs_info,
 133                            "cannot mount because device replace operation is ongoing and");
 134                         btrfs_warn(fs_info,
 135                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 136                            src_devid);
 137                 }
 138                 if (!dev_replace->tgtdev &&
 139                     !btrfs_test_opt(fs_info, DEGRADED)) {
 140                         ret = -EIO;
 141                         btrfs_warn(fs_info,
 142                            "cannot mount because device replace operation is ongoing and");
 143                         btrfs_warn(fs_info,
 144                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 145                                 BTRFS_DEV_REPLACE_DEVID);
 146                 }
 147                 if (dev_replace->tgtdev) {
 148                         if (dev_replace->srcdev) {
 149                                 dev_replace->tgtdev->total_bytes =
 150                                         dev_replace->srcdev->total_bytes;
 151                                 dev_replace->tgtdev->disk_total_bytes =
 152                                         dev_replace->srcdev->disk_total_bytes;
 153                                 dev_replace->tgtdev->commit_total_bytes =
 154                                         dev_replace->srcdev->commit_total_bytes;
 155                                 dev_replace->tgtdev->bytes_used =
 156                                         dev_replace->srcdev->bytes_used;
 157                                 dev_replace->tgtdev->commit_bytes_used =
 158                                         dev_replace->srcdev->commit_bytes_used;
 159                         }
 160                         set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
 161                                 &dev_replace->tgtdev->dev_state);
 162
 163                         WARN_ON(fs_info->fs_devices->rw_devices == 0);
 164                         dev_replace->tgtdev->io_width = fs_info->sectorsize;
 165                         dev_replace->tgtdev->io_align = fs_info->sectorsize;
 166                         dev_replace->tgtdev->sector_size = fs_info->sectorsize;
 167                         dev_replace->tgtdev->fs_info = fs_info;
 168                         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
 169                                 &dev_replace->tgtdev->dev_state);
 170                 }
 171                 break;
 172         }
 173
 174 out:
 175         btrfs_free_path(path);
 176         return ret;
 177 }
 178
 179 /*
 180  * Initialize a new device for device replace target from a given source dev
 181  * and path.
 182  *
 183  * Return 0 and new device in @device_out, otherwise return < 0
 184  */
 185 static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 186                                   const char *device_path,
 187                                   struct btrfs_device *srcdev,
 188                                   struct btrfs_device **device_out)
 189 {
 190         struct btrfs_device *device;
 191         struct block_device *bdev;
 192         struct list_head *devices;
 193         struct rcu_string *name;
 194         u64 devid = BTRFS_DEV_REPLACE_DEVID;
 195         int ret = 0;
 196
 197         *device_out = NULL;
 198         if (fs_info->fs_devices->seeding) {
 199                 btrfs_err(fs_info, "the filesystem is a seed filesystem!");
 200                 return -EINVAL;
 201         }
 202
 203         bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
 204                                   fs_info->bdev_holder);
 205         if (IS_ERR(bdev)) {
 206                 btrfs_err(fs_info, "target device %s is invalid!", device_path);
 207                 return PTR_ERR(bdev);
 208         }
 209
 210         filemap_write_and_wait(bdev->bd_inode->i_mapping);
 211
 212         devices = &fs_info->fs_devices->devices;
 213         list_for_each_entry(device, devices, dev_list) {
 214                 if (device->bdev == bdev) {
 215                         btrfs_err(fs_info,
 216                                   "target device is in the filesystem!");
 217                         ret = -EEXIST;
 218                         goto error;
 219                 }
 220         }
 221
 222
 223         if (i_size_read(bdev->bd_inode) <
 224             btrfs_device_get_total_bytes(srcdev)) {
 225                 btrfs_err(fs_info,
 226                           "target device is smaller than source device!");
 227                 ret = -EINVAL;
 228                 goto error;
 229         }
 230
 231
 232         device = btrfs_alloc_device(NULL, &devid, NULL);
 233         if (IS_ERR(device)) {
 234                 ret = PTR_ERR(device);
 235                 goto error;
 236         }
 237
 238         name = rcu_string_strdup(device_path, GFP_KERNEL);
 239         if (!name) {
 240                 btrfs_free_device(device);
 241                 ret = -ENOMEM;
 242                 goto error;
 243         }
 244         rcu_assign_pointer(device->name, name);
 245
 246         mutex_lock(&fs_info->fs_devices->device_list_mutex);
 247         set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
 248         device->generation = 0;
 249         device->io_width = fs_info->sectorsize;
 250         device->io_align = fs_info->sectorsize;
 251         device->sector_size = fs_info->sectorsize;
 252         device->total_bytes = btrfs_device_get_total_bytes(srcdev);
 253         device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
 254         device->bytes_used = btrfs_device_get_bytes_used(srcdev);
 255         device->commit_total_bytes = srcdev->commit_total_bytes;
 256         device->commit_bytes_used = device->bytes_used;
 257         device->fs_info = fs_info;
 258         device->bdev = bdev;
 259         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 260         set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 261         device->mode = FMODE_EXCL;
 262         device->dev_stats_valid = 1;
 263         set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
 264         device->fs_devices = fs_info->fs_devices;
 265         list_add(&device->dev_list, &fs_info->fs_devices->devices);
 266         fs_info->fs_devices->num_devices++;
 267         fs_info->fs_devices->open_devices++;
 268         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 269
 270         *device_out = device;
 271         return 0;
 272
 273 error:
 274         blkdev_put(bdev, FMODE_EXCL);
 275         return ret;
 276 }
 277
 278 /*
 279  * called from commit_transaction. Writes changed device replace state to
 280  * disk.
 281  */
 282 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 283                           struct btrfs_fs_info *fs_info)
 284 {
 285         int ret;
 286         struct btrfs_root *dev_root = fs_info->dev_root;
 287         struct btrfs_path *path;
 288         struct btrfs_key key;
 289         struct extent_buffer *eb;
 290         struct btrfs_dev_replace_item *ptr;
 291         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 292
 293         btrfs_dev_replace_read_lock(dev_replace);
 294         if (!dev_replace->is_valid ||
 295             !dev_replace->item_needs_writeback) {
 296                 btrfs_dev_replace_read_unlock(dev_replace);
 297                 return 0;
 298         }
 299         btrfs_dev_replace_read_unlock(dev_replace);
 300
 301         key.objectid = 0;
 302         key.type = BTRFS_DEV_REPLACE_KEY;
 303         key.offset = 0;
 304
 305         path = btrfs_alloc_path();
 306         if (!path) {
 307                 ret = -ENOMEM;
 308                 goto out;
 309         }
 310         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 311         if (ret < 0) {
 312                 btrfs_warn(fs_info,
 313                            "error %d while searching for dev_replace item!",
 314                            ret);
 315                 goto out;
 316         }
 317
 318         if (ret == 0 &&
 319             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 320                 /*
 321                  * need to delete old one and insert a new one.
 322                  * Since no attempt is made to recover any old state, if the
 323                  * dev_replace state is 'running', the data on the target
 324                  * drive is lost.
 325                  * It would be possible to recover the state: just make sure
 326                  * that the beginning of the item is never changed and always
 327                  * contains all the essential information. Then read this
 328                  * minimal set of information and use it as a base for the
 329                  * new state.
 330                  */
 331                 ret = btrfs_del_item(trans, dev_root, path);
 332                 if (ret != 0) {
 333                         btrfs_warn(fs_info,
 334                                    "delete too small dev_replace item failed %d!",
 335                                    ret);
 336                         goto out;
 337                 }
 338                 ret = 1;
 339         }
 340
 341         if (ret == 1) {
 342                 /* need to insert a new item */
 343                 btrfs_release_path(path);
 344                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 345                                               &key, sizeof(*ptr));
 346                 if (ret < 0) {
 347                         btrfs_warn(fs_info,
 348                                    "insert dev_replace item failed %d!", ret);
 349                         goto out;
 350                 }
 351         }
 352
 353         eb = path->nodes[0];
 354         ptr = btrfs_item_ptr(eb, path->slots[0],
 355                              struct btrfs_dev_replace_item);
 356
 357         btrfs_dev_replace_write_lock(dev_replace);
 358         if (dev_replace->srcdev)
 359                 btrfs_set_dev_replace_src_devid(eb, ptr,
 360                         dev_replace->srcdev->devid);
 361         else
 362                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 363         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 364                 dev_replace->cont_reading_from_srcdev_mode);
 365         btrfs_set_dev_replace_replace_state(eb, ptr,
 366                 dev_replace->replace_state);
 367         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 368         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 369         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 370                 atomic64_read(&dev_replace->num_write_errors));
 371         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 372                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 373         dev_replace->cursor_left_last_write_of_item =
 374                 dev_replace->cursor_left;
 375         btrfs_set_dev_replace_cursor_left(eb, ptr,
 376                 dev_replace->cursor_left_last_write_of_item);
 377         btrfs_set_dev_replace_cursor_right(eb, ptr,
 378                 dev_replace->cursor_right);
 379         dev_replace->item_needs_writeback = 0;
 380         btrfs_dev_replace_write_unlock(dev_replace);
 381
 382         btrfs_mark_buffer_dirty(eb);
 383
 384 out:
 385         btrfs_free_path(path);
 386
 387         return ret;
 388 }
 389
 390 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 391 {
 392         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 393
 394         dev_replace->committed_cursor_left =
 395                 dev_replace->cursor_left_last_write_of_item;
 396 }
 397
 398 static char* btrfs_dev_name(struct btrfs_device *device)
 399 {
 400         if (!device || test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
 401                 return "<missing disk>";
 402         else
 403                 return rcu_str_deref(device->name);
 404 }
 405
 406 int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 407                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
 408                 int read_src)
 409 {
 410         struct btrfs_root *root = fs_info->dev_root;
 411         struct btrfs_trans_handle *trans;
 412         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 413         int ret;
 414         struct btrfs_device *tgt_device = NULL;
 415         struct btrfs_device *src_device = NULL;
 416
 417         ret = btrfs_find_device_by_devspec(fs_info, srcdevid,
 418                                             srcdev_name, &src_device);
 419         if (ret)
 420                 return ret;
 421
 422         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 423                                             src_device, &tgt_device);
 424         if (ret)
 425                 return ret;
 426
 427         /*
 428          * Here we commit the transaction to make sure commit_total_bytes
 429          * of all the devices are updated.
 430          */
 431         trans = btrfs_attach_transaction(root);
 432         if (!IS_ERR(trans)) {
 433                 ret = btrfs_commit_transaction(trans);
 434                 if (ret)
 435                         return ret;
 436         } else if (PTR_ERR(trans) != -ENOENT) {
 437                 return PTR_ERR(trans);
 438         }
 439
 440         btrfs_dev_replace_write_lock(dev_replace);
 441         switch (dev_replace->replace_state) {
 442         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 443         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 444         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 445                 break;
 446         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 447         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 448                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 449                 goto leave;
 450         }
 451
 452         dev_replace->cont_reading_from_srcdev_mode = read_src;
 453         WARN_ON(!src_device);
 454         dev_replace->srcdev = src_device;
 455         dev_replace->tgtdev = tgt_device;
 456
 457         btrfs_info_in_rcu(fs_info,
 458                       "dev_replace from %s (devid %llu) to %s started",
 459                       btrfs_dev_name(src_device),
 460                       src_device->devid,
 461                       rcu_str_deref(tgt_device->name));
 462
 463         /*
 464          * from now on, the writes to the srcdev are all duplicated to
 465          * go to the tgtdev as well (refer to btrfs_map_block()).
 466          */
 467         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 468         dev_replace->time_started = get_seconds();
 469         dev_replace->cursor_left = 0;
 470         dev_replace->committed_cursor_left = 0;
 471         dev_replace->cursor_left_last_write_of_item = 0;
 472         dev_replace->cursor_right = 0;
 473         dev_replace->is_valid = 1;
 474         dev_replace->item_needs_writeback = 1;
 475         atomic64_set(&dev_replace->num_write_errors, 0);
 476         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 477         btrfs_dev_replace_write_unlock(dev_replace);
 478
 479         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 480         if (ret)
 481                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 482
 483         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 484
 485         /* force writing the updated state information to disk */
 486         trans = btrfs_start_transaction(root, 0);
 487         if (IS_ERR(trans)) {
 488                 ret = PTR_ERR(trans);
 489                 btrfs_dev_replace_write_lock(dev_replace);
 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 {
 505                 WARN_ON(ret);
 506         }
 507
 508         return ret;
 509
 510 leave:
 511         dev_replace->srcdev = NULL;
 512         dev_replace->tgtdev = NULL;
 513         btrfs_dev_replace_write_unlock(dev_replace);
 514         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 515         return ret;
 516 }
 517
 518 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 519                             struct btrfs_ioctl_dev_replace_args *args)
 520 {
 521         int ret;
 522
 523         switch (args->start.cont_reading_from_srcdev_mode) {
 524         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 525         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 526                 break;
 527         default:
 528                 return -EINVAL;
 529         }
 530
 531         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 532             args->start.tgtdev_name[0] == '\0')
 533                 return -EINVAL;
 534
 535         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 536                                         args->start.srcdevid,
 537                                         args->start.srcdev_name,
 538                                         args->start.cont_reading_from_srcdev_mode);
 539         args->result = ret;
 540         /* don't warn if EINPROGRESS, someone else might be running scrub */
 541         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
 542                 ret = 0;
 543
 544         return ret;
 545 }
 546
 547 /*
 548  * blocked until all in-flight bios operations are finished.
 549  */
 550 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 551 {
 552         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 553         wait_event(fs_info->replace_wait, !percpu_counter_sum(
 554                    &fs_info->bio_counter));
 555 }
 556
 557 /*
 558  * we have removed target device, it is safe to allow new bios request.
 559  */
 560 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 561 {
 562         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 563         wake_up(&fs_info->replace_wait);
 564 }
 565
 566 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 567                                        int scrub_ret)
 568 {
 569         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 570         struct btrfs_device *tgt_device;
 571         struct btrfs_device *src_device;
 572         struct btrfs_root *root = fs_info->tree_root;
 573         u8 uuid_tmp[BTRFS_UUID_SIZE];
 574         struct btrfs_trans_handle *trans;
 575         int ret = 0;
 576
 577         /* don't allow cancel or unmount to disturb the finishing procedure */
 578         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 579
 580         btrfs_dev_replace_read_lock(dev_replace);
 581         /* was the operation canceled, or is it finished? */
 582         if (dev_replace->replace_state !=
 583             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 584                 btrfs_dev_replace_read_unlock(dev_replace);
 585                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 586                 return 0;
 587         }
 588
 589         tgt_device = dev_replace->tgtdev;
 590         src_device = dev_replace->srcdev;
 591         btrfs_dev_replace_read_unlock(dev_replace);
 592
 593         /*
 594          * flush all outstanding I/O and inode extent mappings before the
 595          * copy operation is declared as being finished
 596          */
 597         ret = btrfs_start_delalloc_roots(fs_info, -1);
 598         if (ret) {
 599                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 600                 return ret;
 601         }
 602         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 603
 604         trans = btrfs_start_transaction(root, 0);
 605         if (IS_ERR(trans)) {
 606                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 607                 return PTR_ERR(trans);
 608         }
 609         ret = btrfs_commit_transaction(trans);
 610         WARN_ON(ret);
 611
 612         /* keep away write_all_supers() during the finishing procedure */
 613         mutex_lock(&fs_info->fs_devices->device_list_mutex);
 614         mutex_lock(&fs_info->chunk_mutex);
 615         btrfs_dev_replace_write_lock(dev_replace);
 616         dev_replace->replace_state =
 617                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 618                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 619         dev_replace->tgtdev = NULL;
 620         dev_replace->srcdev = NULL;
 621         dev_replace->time_stopped = get_seconds();
 622         dev_replace->item_needs_writeback = 1;
 623
 624         /* replace old device with new one in mapping tree */
 625         if (!scrub_ret) {
 626                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 627                                                                 src_device,
 628                                                                 tgt_device);
 629         } else {
 630                 btrfs_err_in_rcu(fs_info,
 631                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 632                                  btrfs_dev_name(src_device),
 633                                  src_device->devid,
 634                                  rcu_str_deref(tgt_device->name), scrub_ret);
 635                 btrfs_dev_replace_write_unlock(dev_replace);
 636                 mutex_unlock(&fs_info->chunk_mutex);
 637                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 638                 btrfs_rm_dev_replace_blocked(fs_info);
 639                 if (tgt_device)
 640                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 641                 btrfs_rm_dev_replace_unblocked(fs_info);
 642                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 643
 644                 return scrub_ret;
 645         }
 646
 647         btrfs_info_in_rcu(fs_info,
 648                           "dev_replace from %s (devid %llu) to %s finished",
 649                           btrfs_dev_name(src_device),
 650                           src_device->devid,
 651                           rcu_str_deref(tgt_device->name));
 652         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 653         tgt_device->devid = src_device->devid;
 654         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 655         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 656         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 657         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 658         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 659         btrfs_device_set_disk_total_bytes(tgt_device,
 660                                           src_device->disk_total_bytes);
 661         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 662         ASSERT(list_empty(&src_device->resized_list));
 663         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
 664         tgt_device->commit_bytes_used = src_device->bytes_used;
 665
 666         btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
 667
 668         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 669         fs_info->fs_devices->rw_devices++;
 670
 671         btrfs_dev_replace_write_unlock(dev_replace);
 672
 673         btrfs_rm_dev_replace_blocked(fs_info);
 674
 675         btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
 676
 677         btrfs_rm_dev_replace_unblocked(fs_info);
 678
 679         /*
 680          * this is again a consistent state where no dev_replace procedure
 681          * is running, the target device is part of the filesystem, the
 682          * source device is not part of the filesystem anymore and its 1st
 683          * superblock is scratched out so that it is no longer marked to
 684          * belong to this filesystem.
 685          */
 686         mutex_unlock(&fs_info->chunk_mutex);
 687         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 688
 689         /* replace the sysfs entry */
 690         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
 691         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 692
 693         /* write back the superblocks */
 694         trans = btrfs_start_transaction(root, 0);
 695         if (!IS_ERR(trans))
 696                 btrfs_commit_transaction(trans);
 697
 698         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 699
 700         return 0;
 701 }
 702
 703 static void btrfs_dev_replace_update_device_in_mapping_tree(
 704                                                 struct btrfs_fs_info *fs_info,
 705                                                 struct btrfs_device *srcdev,
 706                                                 struct btrfs_device *tgtdev)
 707 {
 708         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 709         struct extent_map *em;
 710         struct map_lookup *map;
 711         u64 start = 0;
 712         int i;
 713
 714         write_lock(&em_tree->lock);
 715         do {
 716                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 717                 if (!em)
 718                         break;
 719                 map = em->map_lookup;
 720                 for (i = 0; i < map->num_stripes; i++)
 721                         if (srcdev == map->stripes[i].dev)
 722                                 map->stripes[i].dev = tgtdev;
 723                 start = em->start + em->len;
 724                 free_extent_map(em);
 725         } while (start);
 726         write_unlock(&em_tree->lock);
 727 }
 728
 729 /*
 730  * Read progress of device replace status according to the state and last
 731  * stored position. The value format is the same as for
 732  * btrfs_dev_replace::progress_1000
 733  */
 734 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
 735 {
 736         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 737         u64 ret = 0;
 738
 739         switch (dev_replace->replace_state) {
 740         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 741         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 742                 ret = 0;
 743                 break;
 744         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 745                 ret = 1000;
 746                 break;
 747         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 748         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 749                 ret = div64_u64(dev_replace->cursor_left,
 750                                 div_u64(btrfs_device_get_total_bytes(
 751                                                 dev_replace->srcdev), 1000));
 752                 break;
 753         }
 754
 755         return ret;
 756 }
 757
 758 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 759                               struct btrfs_ioctl_dev_replace_args *args)
 760 {
 761         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 762
 763         btrfs_dev_replace_read_lock(dev_replace);
 764         /* even if !dev_replace_is_valid, the values are good enough for
 765          * the replace_status ioctl */
 766         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 767         args->status.replace_state = dev_replace->replace_state;
 768         args->status.time_started = dev_replace->time_started;
 769         args->status.time_stopped = dev_replace->time_stopped;
 770         args->status.num_write_errors =
 771                 atomic64_read(&dev_replace->num_write_errors);
 772         args->status.num_uncorrectable_read_errors =
 773                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 774         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
 775         btrfs_dev_replace_read_unlock(dev_replace);
 776 }
 777
 778 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 779 {
 780         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 781         struct btrfs_device *tgt_device = NULL;
 782         struct btrfs_device *src_device = NULL;
 783         struct btrfs_trans_handle *trans;
 784         struct btrfs_root *root = fs_info->tree_root;
 785         int result;
 786         int ret;
 787
 788         if (sb_rdonly(fs_info->sb))
 789                 return -EROFS;
 790
 791         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 792         btrfs_dev_replace_write_lock(dev_replace);
 793         switch (dev_replace->replace_state) {
 794         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 795         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 796         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 797                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 798                 btrfs_dev_replace_write_unlock(dev_replace);
 799                 goto leave;
 800         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 801         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 802                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 803                 tgt_device = dev_replace->tgtdev;
 804                 src_device = dev_replace->srcdev;
 805                 dev_replace->tgtdev = NULL;
 806                 dev_replace->srcdev = NULL;
 807                 break;
 808         }
 809         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 810         dev_replace->time_stopped = get_seconds();
 811         dev_replace->item_needs_writeback = 1;
 812         btrfs_dev_replace_write_unlock(dev_replace);
 813         btrfs_scrub_cancel(fs_info);
 814
 815         trans = btrfs_start_transaction(root, 0);
 816         if (IS_ERR(trans)) {
 817                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 818                 return PTR_ERR(trans);
 819         }
 820         ret = btrfs_commit_transaction(trans);
 821         WARN_ON(ret);
 822
 823         btrfs_info_in_rcu(fs_info,
 824                 "dev_replace from %s (devid %llu) to %s canceled",
 825                 btrfs_dev_name(src_device), src_device->devid,
 826                 btrfs_dev_name(tgt_device));
 827
 828         if (tgt_device)
 829                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 830
 831 leave:
 832         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 833         return result;
 834 }
 835
 836 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 837 {
 838         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 839
 840         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 841         btrfs_dev_replace_write_lock(dev_replace);
 842         switch (dev_replace->replace_state) {
 843         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 844         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 845         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 846         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 847                 break;
 848         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 849                 dev_replace->replace_state =
 850                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 851                 dev_replace->time_stopped = get_seconds();
 852                 dev_replace->item_needs_writeback = 1;
 853                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 854                 break;
 855         }
 856
 857         btrfs_dev_replace_write_unlock(dev_replace);
 858         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 859 }
 860
 861 /* resume dev_replace procedure that was interrupted by unmount */
 862 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 863 {
 864         struct task_struct *task;
 865         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 866
 867         btrfs_dev_replace_write_lock(dev_replace);
 868         switch (dev_replace->replace_state) {
 869         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 870         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 871         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 872                 btrfs_dev_replace_write_unlock(dev_replace);
 873                 return 0;
 874         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 875                 break;
 876         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 877                 dev_replace->replace_state =
 878                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 879                 break;
 880         }
 881         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 882                 btrfs_info(fs_info,
 883                            "cannot continue dev_replace, tgtdev is missing");
 884                 btrfs_info(fs_info,
 885                            "you may cancel the operation after 'mount -o degraded'");
 886                 btrfs_dev_replace_write_unlock(dev_replace);
 887                 return 0;
 888         }
 889         btrfs_dev_replace_write_unlock(dev_replace);
 890
 891         /*
 892          * This could collide with a paused balance, but the exclusive op logic
 893          * should never allow both to start and pause. We don't want to allow
 894          * dev-replace to start anyway.
 895          */
 896         if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
 897                 btrfs_info(fs_info,
 898                 "cannot resume dev-replace, other exclusive operation running");
 899                 return 0;
 900         }
 901
 902         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 903         return PTR_ERR_OR_ZERO(task);
 904 }
 905
 906 static int btrfs_dev_replace_kthread(void *data)
 907 {
 908         struct btrfs_fs_info *fs_info = data;
 909         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 910         u64 progress;
 911         int ret;
 912
 913         progress = btrfs_dev_replace_progress(fs_info);
 914         progress = div_u64(progress, 10);
 915         btrfs_info_in_rcu(fs_info,
 916                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
 917                 btrfs_dev_name(dev_replace->srcdev),
 918                 dev_replace->srcdev->devid,
 919                 btrfs_dev_name(dev_replace->tgtdev),
 920                 (unsigned int)progress);
 921
 922         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 923                               dev_replace->committed_cursor_left,
 924                               btrfs_device_get_total_bytes(dev_replace->srcdev),
 925                               &dev_replace->scrub_progress, 0, 1);
 926         ret = btrfs_dev_replace_finishing(fs_info, ret);
 927         WARN_ON(ret);
 928
 929         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
 930         return 0;
 931 }
 932
 933 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 934 {
 935         if (!dev_replace->is_valid)
 936                 return 0;
 937
 938         switch (dev_replace->replace_state) {
 939         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 940         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 941         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 942                 return 0;
 943         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 944         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 945                 /*
 946                  * return true even if tgtdev is missing (this is
 947                  * something that can happen if the dev_replace
 948                  * procedure is suspended by an umount and then
 949                  * the tgtdev is missing (or "btrfs dev scan") was
 950                  * not called and the the filesystem is remounted
 951                  * in degraded state. This does not stop the
 952                  * dev_replace procedure. It needs to be canceled
 953                  * manually if the cancellation is wanted.
 954                  */
 955                 break;
 956         }
 957         return 1;
 958 }
 959
 960 void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace)
 961 {
 962         read_lock(&dev_replace->lock);
 963         atomic_inc(&dev_replace->read_locks);
 964 }
 965
 966 void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace)
 967 {
 968         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 969         atomic_dec(&dev_replace->read_locks);
 970         read_unlock(&dev_replace->lock);
 971 }
 972
 973 void btrfs_dev_replace_write_lock(struct btrfs_dev_replace *dev_replace)
 974 {
 975 again:
 976         wait_event(dev_replace->read_lock_wq,
 977                    atomic_read(&dev_replace->blocking_readers) == 0);
 978         write_lock(&dev_replace->lock);
 979         if (atomic_read(&dev_replace->blocking_readers)) {
 980                 write_unlock(&dev_replace->lock);
 981                 goto again;
 982         }
 983 }
 984
 985 void btrfs_dev_replace_write_unlock(struct btrfs_dev_replace *dev_replace)
 986 {
 987         ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
 988         write_unlock(&dev_replace->lock);
 989 }
 990
 991 /* inc blocking cnt and release read lock */
 992 void btrfs_dev_replace_set_lock_blocking(
 993                                         struct btrfs_dev_replace *dev_replace)
 994 {
 995         /* only set blocking for read lock */
 996         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 997         atomic_inc(&dev_replace->blocking_readers);
 998         read_unlock(&dev_replace->lock);
 999 }
1000
1001 /* acquire read lock and dec blocking cnt */
1002 void btrfs_dev_replace_clear_lock_blocking(
1003                                         struct btrfs_dev_replace *dev_replace)
1004 {
1005         /* only set blocking for read lock */
1006         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
1007         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
1008         read_lock(&dev_replace->lock);
1009         /* Barrier implied by atomic_dec_and_test */
1010         if (atomic_dec_and_test(&dev_replace->blocking_readers))
1011                 cond_wake_up_nomb(&dev_replace->read_lock_wq);
1012 }
1013
1014 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
1015 {
1016         percpu_counter_inc(&fs_info->bio_counter);
1017 }
1018
1019 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1020 {
1021         percpu_counter_sub(&fs_info->bio_counter, amount);
1022         cond_wake_up_nomb(&fs_info->replace_wait);
1023 }
1024
1025 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1026 {
1027         while (1) {
1028                 percpu_counter_inc(&fs_info->bio_counter);
1029                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1030                                      &fs_info->fs_state)))
1031                         break;
1032
1033                 btrfs_bio_counter_dec(fs_info);
1034                 wait_event(fs_info->replace_wait,
1035                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1036                                      &fs_info->fs_state));
1037         }
1038 }