fs/btrfs/dev-replace.c

   1 /*
   2  * Copyright (C) STRATO AG 2012.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18 #include <linux/sched.h>
  19 #include <linux/bio.h>
  20 #include <linux/slab.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/random.h>
  24 #include <linux/iocontext.h>
  25 #include <linux/capability.h>
  26 #include <linux/kthread.h>
  27 #include <linux/math64.h>
  28 #include <asm/div64.h>
  29 #include "ctree.h"
  30 #include "extent_map.h"
  31 #include "disk-io.h"
  32 #include "transaction.h"
  33 #include "print-tree.h"
  34 #include "volumes.h"
  35 #include "async-thread.h"
  36 #include "check-integrity.h"
  37 #include "rcu-string.h"
  38 #include "dev-replace.h"
  39 #include "sysfs.h"
  40
  41 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
  42                                        int scrub_ret);
  43 static void btrfs_dev_replace_update_device_in_mapping_tree(
  44                                                 struct btrfs_fs_info *fs_info,
  45                                                 struct btrfs_device *srcdev,
  46                                                 struct btrfs_device *tgtdev);
  47 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info);
  48 static int btrfs_dev_replace_kthread(void *data);
  49 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
  50
  51
  52 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  53 {
  54         struct btrfs_key key;
  55         struct btrfs_root *dev_root = fs_info->dev_root;
  56         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  57         struct extent_buffer *eb;
  58         int slot;
  59         int ret = 0;
  60         struct btrfs_path *path = NULL;
  61         int item_size;
  62         struct btrfs_dev_replace_item *ptr;
  63         u64 src_devid;
  64
  65         path = btrfs_alloc_path();
  66         if (!path) {
  67                 ret = -ENOMEM;
  68                 goto out;
  69         }
  70
  71         key.objectid = 0;
  72         key.type = BTRFS_DEV_REPLACE_KEY;
  73         key.offset = 0;
  74         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  75         if (ret) {
  76 no_valid_dev_replace_entry_found:
  77                 ret = 0;
  78                 dev_replace->replace_state =
  79                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
  80                 dev_replace->cont_reading_from_srcdev_mode =
  81                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
  82                 dev_replace->replace_state = 0;
  83                 dev_replace->time_started = 0;
  84                 dev_replace->time_stopped = 0;
  85                 atomic64_set(&dev_replace->num_write_errors, 0);
  86                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
  87                 dev_replace->cursor_left = 0;
  88                 dev_replace->committed_cursor_left = 0;
  89                 dev_replace->cursor_left_last_write_of_item = 0;
  90                 dev_replace->cursor_right = 0;
  91                 dev_replace->srcdev = NULL;
  92                 dev_replace->tgtdev = NULL;
  93                 dev_replace->is_valid = 0;
  94                 dev_replace->item_needs_writeback = 0;
  95                 goto out;
  96         }
  97         slot = path->slots[0];
  98         eb = path->nodes[0];
  99         item_size = btrfs_item_size_nr(eb, slot);
 100         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
 101
 102         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
 103                 btrfs_warn(fs_info,
 104                         "dev_replace entry found has unexpected size, ignore entry");
 105                 goto no_valid_dev_replace_entry_found;
 106         }
 107
 108         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
 109         dev_replace->cont_reading_from_srcdev_mode =
 110                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
 111         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
 112         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
 113         dev_replace->time_stopped =
 114                 btrfs_dev_replace_time_stopped(eb, ptr);
 115         atomic64_set(&dev_replace->num_write_errors,
 116                      btrfs_dev_replace_num_write_errors(eb, ptr));
 117         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 118                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 119         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 120         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 121         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 122         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 123         dev_replace->is_valid = 1;
 124
 125         dev_replace->item_needs_writeback = 0;
 126         switch (dev_replace->replace_state) {
 127         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 128         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 129         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 130                 dev_replace->srcdev = NULL;
 131                 dev_replace->tgtdev = NULL;
 132                 break;
 133         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 134         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 135                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
 136                                                         NULL, NULL);
 137                 dev_replace->tgtdev = btrfs_find_device(fs_info,
 138                                                         BTRFS_DEV_REPLACE_DEVID,
 139                                                         NULL, NULL);
 140                 /*
 141                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 142                  * missing
 143                  */
 144                 if (!dev_replace->srcdev &&
 145                     !btrfs_test_opt(fs_info, DEGRADED)) {
 146                         ret = -EIO;
 147                         btrfs_warn(fs_info,
 148                            "cannot mount because device replace operation is ongoing and");
 149                         btrfs_warn(fs_info,
 150                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 151                            src_devid);
 152                 }
 153                 if (!dev_replace->tgtdev &&
 154                     !btrfs_test_opt(fs_info, DEGRADED)) {
 155                         ret = -EIO;
 156                         btrfs_warn(fs_info,
 157                            "cannot mount because device replace operation is ongoing and");
 158                         btrfs_warn(fs_info,
 159                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 160                                 BTRFS_DEV_REPLACE_DEVID);
 161                 }
 162                 if (dev_replace->tgtdev) {
 163                         if (dev_replace->srcdev) {
 164                                 dev_replace->tgtdev->total_bytes =
 165                                         dev_replace->srcdev->total_bytes;
 166                                 dev_replace->tgtdev->disk_total_bytes =
 167                                         dev_replace->srcdev->disk_total_bytes;
 168                                 dev_replace->tgtdev->commit_total_bytes =
 169                                         dev_replace->srcdev->commit_total_bytes;
 170                                 dev_replace->tgtdev->bytes_used =
 171                                         dev_replace->srcdev->bytes_used;
 172                                 dev_replace->tgtdev->commit_bytes_used =
 173                                         dev_replace->srcdev->commit_bytes_used;
 174                         }
 175                         dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
 176                         btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
 177                                 dev_replace->tgtdev);
 178                 }
 179                 break;
 180         }
 181
 182 out:
 183         btrfs_free_path(path);
 184         return ret;
 185 }
 186
 187 /*
 188  * called from commit_transaction. Writes changed device replace state to
 189  * disk.
 190  */
 191 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 192                           struct btrfs_fs_info *fs_info)
 193 {
 194         int ret;
 195         struct btrfs_root *dev_root = fs_info->dev_root;
 196         struct btrfs_path *path;
 197         struct btrfs_key key;
 198         struct extent_buffer *eb;
 199         struct btrfs_dev_replace_item *ptr;
 200         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 201
 202         btrfs_dev_replace_lock(dev_replace, 0);
 203         if (!dev_replace->is_valid ||
 204             !dev_replace->item_needs_writeback) {
 205                 btrfs_dev_replace_unlock(dev_replace, 0);
 206                 return 0;
 207         }
 208         btrfs_dev_replace_unlock(dev_replace, 0);
 209
 210         key.objectid = 0;
 211         key.type = BTRFS_DEV_REPLACE_KEY;
 212         key.offset = 0;
 213
 214         path = btrfs_alloc_path();
 215         if (!path) {
 216                 ret = -ENOMEM;
 217                 goto out;
 218         }
 219         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 220         if (ret < 0) {
 221                 btrfs_warn(fs_info,
 222                            "error %d while searching for dev_replace item!",
 223                            ret);
 224                 goto out;
 225         }
 226
 227         if (ret == 0 &&
 228             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 229                 /*
 230                  * need to delete old one and insert a new one.
 231                  * Since no attempt is made to recover any old state, if the
 232                  * dev_replace state is 'running', the data on the target
 233                  * drive is lost.
 234                  * It would be possible to recover the state: just make sure
 235                  * that the beginning of the item is never changed and always
 236                  * contains all the essential information. Then read this
 237                  * minimal set of information and use it as a base for the
 238                  * new state.
 239                  */
 240                 ret = btrfs_del_item(trans, dev_root, path);
 241                 if (ret != 0) {
 242                         btrfs_warn(fs_info,
 243                                    "delete too small dev_replace item failed %d!",
 244                                    ret);
 245                         goto out;
 246                 }
 247                 ret = 1;
 248         }
 249
 250         if (ret == 1) {
 251                 /* need to insert a new item */
 252                 btrfs_release_path(path);
 253                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 254                                               &key, sizeof(*ptr));
 255                 if (ret < 0) {
 256                         btrfs_warn(fs_info,
 257                                    "insert dev_replace item failed %d!", ret);
 258                         goto out;
 259                 }
 260         }
 261
 262         eb = path->nodes[0];
 263         ptr = btrfs_item_ptr(eb, path->slots[0],
 264                              struct btrfs_dev_replace_item);
 265
 266         btrfs_dev_replace_lock(dev_replace, 1);
 267         if (dev_replace->srcdev)
 268                 btrfs_set_dev_replace_src_devid(eb, ptr,
 269                         dev_replace->srcdev->devid);
 270         else
 271                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 272         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 273                 dev_replace->cont_reading_from_srcdev_mode);
 274         btrfs_set_dev_replace_replace_state(eb, ptr,
 275                 dev_replace->replace_state);
 276         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 277         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 278         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 279                 atomic64_read(&dev_replace->num_write_errors));
 280         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 281                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 282         dev_replace->cursor_left_last_write_of_item =
 283                 dev_replace->cursor_left;
 284         btrfs_set_dev_replace_cursor_left(eb, ptr,
 285                 dev_replace->cursor_left_last_write_of_item);
 286         btrfs_set_dev_replace_cursor_right(eb, ptr,
 287                 dev_replace->cursor_right);
 288         dev_replace->item_needs_writeback = 0;
 289         btrfs_dev_replace_unlock(dev_replace, 1);
 290
 291         btrfs_mark_buffer_dirty(eb);
 292
 293 out:
 294         btrfs_free_path(path);
 295
 296         return ret;
 297 }
 298
 299 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 300 {
 301         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 302
 303         dev_replace->committed_cursor_left =
 304                 dev_replace->cursor_left_last_write_of_item;
 305 }
 306
 307 int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 308                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
 309                 int read_src)
 310 {
 311         struct btrfs_root *root = fs_info->dev_root;
 312         struct btrfs_trans_handle *trans;
 313         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 314         int ret;
 315         struct btrfs_device *tgt_device = NULL;
 316         struct btrfs_device *src_device = NULL;
 317
 318         /* the disk copy procedure reuses the scrub code */
 319         mutex_lock(&fs_info->volume_mutex);
 320         ret = btrfs_find_device_by_devspec(fs_info, srcdevid,
 321                                             srcdev_name, &src_device);
 322         if (ret) {
 323                 mutex_unlock(&fs_info->volume_mutex);
 324                 return ret;
 325         }
 326
 327         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 328                                             src_device, &tgt_device);
 329         mutex_unlock(&fs_info->volume_mutex);
 330         if (ret)
 331                 return ret;
 332
 333         /*
 334          * Here we commit the transaction to make sure commit_total_bytes
 335          * of all the devices are updated.
 336          */
 337         trans = btrfs_attach_transaction(root);
 338         if (!IS_ERR(trans)) {
 339                 ret = btrfs_commit_transaction(trans);
 340                 if (ret)
 341                         return ret;
 342         } else if (PTR_ERR(trans) != -ENOENT) {
 343                 return PTR_ERR(trans);
 344         }
 345
 346         btrfs_dev_replace_lock(dev_replace, 1);
 347         switch (dev_replace->replace_state) {
 348         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 349         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 350         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 351                 break;
 352         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 353         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 354                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 355                 goto leave;
 356         }
 357
 358         dev_replace->cont_reading_from_srcdev_mode = read_src;
 359         WARN_ON(!src_device);
 360         dev_replace->srcdev = src_device;
 361         WARN_ON(!tgt_device);
 362         dev_replace->tgtdev = tgt_device;
 363
 364         btrfs_info_in_rcu(fs_info,
 365                       "dev_replace from %s (devid %llu) to %s started",
 366                       src_device->missing ? "<missing disk>" :
 367                         rcu_str_deref(src_device->name),
 368                       src_device->devid,
 369                       rcu_str_deref(tgt_device->name));
 370
 371         /*
 372          * from now on, the writes to the srcdev are all duplicated to
 373          * go to the tgtdev as well (refer to btrfs_map_block()).
 374          */
 375         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 376         dev_replace->time_started = get_seconds();
 377         dev_replace->cursor_left = 0;
 378         dev_replace->committed_cursor_left = 0;
 379         dev_replace->cursor_left_last_write_of_item = 0;
 380         dev_replace->cursor_right = 0;
 381         dev_replace->is_valid = 1;
 382         dev_replace->item_needs_writeback = 1;
 383         atomic64_set(&dev_replace->num_write_errors, 0);
 384         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 385         btrfs_dev_replace_unlock(dev_replace, 1);
 386
 387         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 388         if (ret)
 389                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 390
 391         btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
 392
 393         /* force writing the updated state information to disk */
 394         trans = btrfs_start_transaction(root, 0);
 395         if (IS_ERR(trans)) {
 396                 ret = PTR_ERR(trans);
 397                 btrfs_dev_replace_lock(dev_replace, 1);
 398                 goto leave;
 399         }
 400
 401         ret = btrfs_commit_transaction(trans);
 402         WARN_ON(ret);
 403
 404         /* the disk copy procedure reuses the scrub code */
 405         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 406                               btrfs_device_get_total_bytes(src_device),
 407                               &dev_replace->scrub_progress, 0, 1);
 408
 409         ret = btrfs_dev_replace_finishing(fs_info, ret);
 410         if (ret == -EINPROGRESS) {
 411                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 412         } else {
 413                 WARN_ON(ret);
 414         }
 415
 416         return ret;
 417
 418 leave:
 419         dev_replace->srcdev = NULL;
 420         dev_replace->tgtdev = NULL;
 421         btrfs_dev_replace_unlock(dev_replace, 1);
 422         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 423         return ret;
 424 }
 425
 426 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 427                             struct btrfs_ioctl_dev_replace_args *args)
 428 {
 429         int ret;
 430
 431         switch (args->start.cont_reading_from_srcdev_mode) {
 432         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 433         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 434                 break;
 435         default:
 436                 return -EINVAL;
 437         }
 438
 439         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 440             args->start.tgtdev_name[0] == '\0')
 441                 return -EINVAL;
 442
 443         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 444                                         args->start.srcdevid,
 445                                         args->start.srcdev_name,
 446                                         args->start.cont_reading_from_srcdev_mode);
 447         args->result = ret;
 448         /* don't warn if EINPROGRESS, someone else might be running scrub */
 449         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
 450                 ret = 0;
 451
 452         return ret;
 453 }
 454
 455 /*
 456  * blocked until all in-flight bios operations are finished.
 457  */
 458 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 459 {
 460         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 461         wait_event(fs_info->replace_wait, !percpu_counter_sum(
 462                    &fs_info->bio_counter));
 463 }
 464
 465 /*
 466  * we have removed target device, it is safe to allow new bios request.
 467  */
 468 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 469 {
 470         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 471         wake_up(&fs_info->replace_wait);
 472 }
 473
 474 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 475                                        int scrub_ret)
 476 {
 477         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 478         struct btrfs_device *tgt_device;
 479         struct btrfs_device *src_device;
 480         struct btrfs_root *root = fs_info->tree_root;
 481         u8 uuid_tmp[BTRFS_UUID_SIZE];
 482         struct btrfs_trans_handle *trans;
 483         int ret = 0;
 484
 485         /* don't allow cancel or unmount to disturb the finishing procedure */
 486         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 487
 488         btrfs_dev_replace_lock(dev_replace, 0);
 489         /* was the operation canceled, or is it finished? */
 490         if (dev_replace->replace_state !=
 491             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 492                 btrfs_dev_replace_unlock(dev_replace, 0);
 493                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 494                 return 0;
 495         }
 496
 497         tgt_device = dev_replace->tgtdev;
 498         src_device = dev_replace->srcdev;
 499         btrfs_dev_replace_unlock(dev_replace, 0);
 500
 501         /*
 502          * flush all outstanding I/O and inode extent mappings before the
 503          * copy operation is declared as being finished
 504          */
 505         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
 506         if (ret) {
 507                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 508                 return ret;
 509         }
 510         btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
 511
 512         trans = btrfs_start_transaction(root, 0);
 513         if (IS_ERR(trans)) {
 514                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 515                 return PTR_ERR(trans);
 516         }
 517         ret = btrfs_commit_transaction(trans);
 518         WARN_ON(ret);
 519
 520         mutex_lock(&uuid_mutex);
 521         /* keep away write_all_supers() during the finishing procedure */
 522         mutex_lock(&fs_info->fs_devices->device_list_mutex);
 523         mutex_lock(&fs_info->chunk_mutex);
 524         btrfs_dev_replace_lock(dev_replace, 1);
 525         dev_replace->replace_state =
 526                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 527                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 528         dev_replace->tgtdev = NULL;
 529         dev_replace->srcdev = NULL;
 530         dev_replace->time_stopped = get_seconds();
 531         dev_replace->item_needs_writeback = 1;
 532
 533         /* replace old device with new one in mapping tree */
 534         if (!scrub_ret) {
 535                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 536                                                                 src_device,
 537                                                                 tgt_device);
 538         } else {
 539                 btrfs_err_in_rcu(fs_info,
 540                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 541                                  src_device->missing ? "<missing disk>" :
 542                                  rcu_str_deref(src_device->name),
 543                                  src_device->devid,
 544                                  rcu_str_deref(tgt_device->name), scrub_ret);
 545                 btrfs_dev_replace_unlock(dev_replace, 1);
 546                 mutex_unlock(&fs_info->chunk_mutex);
 547                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 548                 mutex_unlock(&uuid_mutex);
 549                 if (tgt_device)
 550                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 551                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 552
 553                 return scrub_ret;
 554         }
 555
 556         btrfs_info_in_rcu(fs_info,
 557                           "dev_replace from %s (devid %llu) to %s finished",
 558                           src_device->missing ? "<missing disk>" :
 559                           rcu_str_deref(src_device->name),
 560                           src_device->devid,
 561                           rcu_str_deref(tgt_device->name));
 562         tgt_device->is_tgtdev_for_dev_replace = 0;
 563         tgt_device->devid = src_device->devid;
 564         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 565         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 566         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 567         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 568         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 569         btrfs_device_set_disk_total_bytes(tgt_device,
 570                                           src_device->disk_total_bytes);
 571         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 572         ASSERT(list_empty(&src_device->resized_list));
 573         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
 574         tgt_device->commit_bytes_used = src_device->bytes_used;
 575
 576         btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
 577
 578         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 579         fs_info->fs_devices->rw_devices++;
 580
 581         btrfs_dev_replace_unlock(dev_replace, 1);
 582
 583         btrfs_rm_dev_replace_blocked(fs_info);
 584
 585         btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
 586
 587         btrfs_rm_dev_replace_unblocked(fs_info);
 588
 589         /*
 590          * this is again a consistent state where no dev_replace procedure
 591          * is running, the target device is part of the filesystem, the
 592          * source device is not part of the filesystem anymore and its 1st
 593          * superblock is scratched out so that it is no longer marked to
 594          * belong to this filesystem.
 595          */
 596         mutex_unlock(&fs_info->chunk_mutex);
 597         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 598         mutex_unlock(&uuid_mutex);
 599
 600         /* replace the sysfs entry */
 601         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
 602         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 603
 604         /* write back the superblocks */
 605         trans = btrfs_start_transaction(root, 0);
 606         if (!IS_ERR(trans))
 607                 btrfs_commit_transaction(trans);
 608
 609         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 610
 611         return 0;
 612 }
 613
 614 static void btrfs_dev_replace_update_device_in_mapping_tree(
 615                                                 struct btrfs_fs_info *fs_info,
 616                                                 struct btrfs_device *srcdev,
 617                                                 struct btrfs_device *tgtdev)
 618 {
 619         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 620         struct extent_map *em;
 621         struct map_lookup *map;
 622         u64 start = 0;
 623         int i;
 624
 625         write_lock(&em_tree->lock);
 626         do {
 627                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 628                 if (!em)
 629                         break;
 630                 map = em->map_lookup;
 631                 for (i = 0; i < map->num_stripes; i++)
 632                         if (srcdev == map->stripes[i].dev)
 633                                 map->stripes[i].dev = tgtdev;
 634                 start = em->start + em->len;
 635                 free_extent_map(em);
 636         } while (start);
 637         write_unlock(&em_tree->lock);
 638 }
 639
 640 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 641                               struct btrfs_ioctl_dev_replace_args *args)
 642 {
 643         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 644         struct btrfs_device *srcdev;
 645
 646         btrfs_dev_replace_lock(dev_replace, 0);
 647         /* even if !dev_replace_is_valid, the values are good enough for
 648          * the replace_status ioctl */
 649         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 650         args->status.replace_state = dev_replace->replace_state;
 651         args->status.time_started = dev_replace->time_started;
 652         args->status.time_stopped = dev_replace->time_stopped;
 653         args->status.num_write_errors =
 654                 atomic64_read(&dev_replace->num_write_errors);
 655         args->status.num_uncorrectable_read_errors =
 656                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 657         switch (dev_replace->replace_state) {
 658         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 659         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 660                 args->status.progress_1000 = 0;
 661                 break;
 662         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 663                 args->status.progress_1000 = 1000;
 664                 break;
 665         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 666         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 667                 srcdev = dev_replace->srcdev;
 668                 args->status.progress_1000 = div_u64(dev_replace->cursor_left,
 669                         div_u64(btrfs_device_get_total_bytes(srcdev), 1000));
 670                 break;
 671         }
 672         btrfs_dev_replace_unlock(dev_replace, 0);
 673 }
 674
 675 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 676                              struct btrfs_ioctl_dev_replace_args *args)
 677 {
 678         args->result = __btrfs_dev_replace_cancel(fs_info);
 679         return 0;
 680 }
 681
 682 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 683 {
 684         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 685         struct btrfs_device *tgt_device = NULL;
 686         struct btrfs_trans_handle *trans;
 687         struct btrfs_root *root = fs_info->tree_root;
 688         u64 result;
 689         int ret;
 690
 691         if (fs_info->sb->s_flags & MS_RDONLY)
 692                 return -EROFS;
 693
 694         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 695         btrfs_dev_replace_lock(dev_replace, 1);
 696         switch (dev_replace->replace_state) {
 697         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 698         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 699         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 700                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 701                 btrfs_dev_replace_unlock(dev_replace, 1);
 702                 goto leave;
 703         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 704         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 705                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 706                 tgt_device = dev_replace->tgtdev;
 707                 dev_replace->tgtdev = NULL;
 708                 dev_replace->srcdev = NULL;
 709                 break;
 710         }
 711         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 712         dev_replace->time_stopped = get_seconds();
 713         dev_replace->item_needs_writeback = 1;
 714         btrfs_dev_replace_unlock(dev_replace, 1);
 715         btrfs_scrub_cancel(fs_info);
 716
 717         trans = btrfs_start_transaction(root, 0);
 718         if (IS_ERR(trans)) {
 719                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 720                 return PTR_ERR(trans);
 721         }
 722         ret = btrfs_commit_transaction(trans);
 723         WARN_ON(ret);
 724         if (tgt_device)
 725                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 726
 727 leave:
 728         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 729         return result;
 730 }
 731
 732 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 733 {
 734         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 735
 736         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 737         btrfs_dev_replace_lock(dev_replace, 1);
 738         switch (dev_replace->replace_state) {
 739         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 740         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 741         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 742         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 743                 break;
 744         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 745                 dev_replace->replace_state =
 746                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 747                 dev_replace->time_stopped = get_seconds();
 748                 dev_replace->item_needs_writeback = 1;
 749                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 750                 break;
 751         }
 752
 753         btrfs_dev_replace_unlock(dev_replace, 1);
 754         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 755 }
 756
 757 /* resume dev_replace procedure that was interrupted by unmount */
 758 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 759 {
 760         struct task_struct *task;
 761         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 762
 763         btrfs_dev_replace_lock(dev_replace, 1);
 764         switch (dev_replace->replace_state) {
 765         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 766         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 767         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 768                 btrfs_dev_replace_unlock(dev_replace, 1);
 769                 return 0;
 770         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 771                 break;
 772         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 773                 dev_replace->replace_state =
 774                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 775                 break;
 776         }
 777         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 778                 btrfs_info(fs_info,
 779                            "cannot continue dev_replace, tgtdev is missing");
 780                 btrfs_info(fs_info,
 781                            "you may cancel the operation after 'mount -o degraded'");
 782                 btrfs_dev_replace_unlock(dev_replace, 1);
 783                 return 0;
 784         }
 785         btrfs_dev_replace_unlock(dev_replace, 1);
 786
 787         WARN_ON(atomic_xchg(
 788                 &fs_info->mutually_exclusive_operation_running, 1));
 789         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 790         return PTR_ERR_OR_ZERO(task);
 791 }
 792
 793 static int btrfs_dev_replace_kthread(void *data)
 794 {
 795         struct btrfs_fs_info *fs_info = data;
 796         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 797         struct btrfs_ioctl_dev_replace_args *status_args;
 798         u64 progress;
 799
 800         status_args = kzalloc(sizeof(*status_args), GFP_KERNEL);
 801         if (status_args) {
 802                 btrfs_dev_replace_status(fs_info, status_args);
 803                 progress = status_args->status.progress_1000;
 804                 kfree(status_args);
 805                 progress = div_u64(progress, 10);
 806                 btrfs_info_in_rcu(fs_info,
 807                         "continuing dev_replace from %s (devid %llu) to %s @%u%%",
 808                         dev_replace->srcdev->missing ? "<missing disk>" :
 809                         rcu_str_deref(dev_replace->srcdev->name),
 810                         dev_replace->srcdev->devid,
 811                         dev_replace->tgtdev ?
 812                         rcu_str_deref(dev_replace->tgtdev->name) :
 813                         "<missing target disk>",
 814                         (unsigned int)progress);
 815         }
 816         btrfs_dev_replace_continue_on_mount(fs_info);
 817         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
 818
 819         return 0;
 820 }
 821
 822 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 823 {
 824         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 825         int ret;
 826
 827         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 828                               dev_replace->committed_cursor_left,
 829                               btrfs_device_get_total_bytes(dev_replace->srcdev),
 830                               &dev_replace->scrub_progress, 0, 1);
 831         ret = btrfs_dev_replace_finishing(fs_info, ret);
 832         WARN_ON(ret);
 833         return 0;
 834 }
 835
 836 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 837 {
 838         if (!dev_replace->is_valid)
 839                 return 0;
 840
 841         switch (dev_replace->replace_state) {
 842         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 843         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 844         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 845                 return 0;
 846         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 847         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 848                 /*
 849                  * return true even if tgtdev is missing (this is
 850                  * something that can happen if the dev_replace
 851                  * procedure is suspended by an umount and then
 852                  * the tgtdev is missing (or "btrfs dev scan") was
 853                  * not called and the the filesystem is remounted
 854                  * in degraded state. This does not stop the
 855                  * dev_replace procedure. It needs to be canceled
 856                  * manually if the cancellation is wanted.
 857                  */
 858                 break;
 859         }
 860         return 1;
 861 }
 862
 863 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
 864 {
 865         if (rw == 1) {
 866                 /* write */
 867 again:
 868                 wait_event(dev_replace->read_lock_wq,
 869                            atomic_read(&dev_replace->blocking_readers) == 0);
 870                 write_lock(&dev_replace->lock);
 871                 if (atomic_read(&dev_replace->blocking_readers)) {
 872                         write_unlock(&dev_replace->lock);
 873                         goto again;
 874                 }
 875         } else {
 876                 read_lock(&dev_replace->lock);
 877                 atomic_inc(&dev_replace->read_locks);
 878         }
 879 }
 880
 881 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
 882 {
 883         if (rw == 1) {
 884                 /* write */
 885                 ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
 886                 write_unlock(&dev_replace->lock);
 887         } else {
 888                 ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 889                 atomic_dec(&dev_replace->read_locks);
 890                 read_unlock(&dev_replace->lock);
 891         }
 892 }
 893
 894 /* inc blocking cnt and release read lock */
 895 void btrfs_dev_replace_set_lock_blocking(
 896                                         struct btrfs_dev_replace *dev_replace)
 897 {
 898         /* only set blocking for read lock */
 899         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 900         atomic_inc(&dev_replace->blocking_readers);
 901         read_unlock(&dev_replace->lock);
 902 }
 903
 904 /* acquire read lock and dec blocking cnt */
 905 void btrfs_dev_replace_clear_lock_blocking(
 906                                         struct btrfs_dev_replace *dev_replace)
 907 {
 908         /* only set blocking for read lock */
 909         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 910         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
 911         read_lock(&dev_replace->lock);
 912         if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
 913             waitqueue_active(&dev_replace->read_lock_wq))
 914                 wake_up(&dev_replace->read_lock_wq);
 915 }
 916
 917 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
 918 {
 919         percpu_counter_inc(&fs_info->bio_counter);
 920 }
 921
 922 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
 923 {
 924         percpu_counter_sub(&fs_info->bio_counter, amount);
 925
 926         if (waitqueue_active(&fs_info->replace_wait))
 927                 wake_up(&fs_info->replace_wait);
 928 }
 929
 930 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
 931 {
 932         while (1) {
 933                 percpu_counter_inc(&fs_info->bio_counter);
 934                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 935                                      &fs_info->fs_state)))
 936                         break;
 937
 938                 btrfs_bio_counter_dec(fs_info);
 939                 wait_event(fs_info->replace_wait,
 940                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 941                                      &fs_info->fs_state));
 942         }
 943 }