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, char *tgtdev_name,
 308                                 u64 srcdevid, char *srcdev_name, int read_src)
 309 {
 310         struct btrfs_root *root = fs_info->dev_root;
 311         struct btrfs_trans_handle *trans;
 312         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 313         int ret;
 314         struct btrfs_device *tgt_device = NULL;
 315         struct btrfs_device *src_device = NULL;
 316
 317         /* the disk copy procedure reuses the scrub code */
 318         mutex_lock(&fs_info->volume_mutex);
 319         ret = btrfs_find_device_by_devspec(fs_info, srcdevid,
 320                                             srcdev_name, &src_device);
 321         if (ret) {
 322                 mutex_unlock(&fs_info->volume_mutex);
 323                 return ret;
 324         }
 325
 326         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 327                                             src_device, &tgt_device);
 328         mutex_unlock(&fs_info->volume_mutex);
 329         if (ret)
 330                 return ret;
 331
 332         /*
 333          * Here we commit the transaction to make sure commit_total_bytes
 334          * of all the devices are updated.
 335          */
 336         trans = btrfs_attach_transaction(root);
 337         if (!IS_ERR(trans)) {
 338                 ret = btrfs_commit_transaction(trans);
 339                 if (ret)
 340                         return ret;
 341         } else if (PTR_ERR(trans) != -ENOENT) {
 342                 return PTR_ERR(trans);
 343         }
 344
 345         btrfs_dev_replace_lock(dev_replace, 1);
 346         switch (dev_replace->replace_state) {
 347         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 348         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 349         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 350                 break;
 351         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 352         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 353                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 354                 goto leave;
 355         }
 356
 357         dev_replace->cont_reading_from_srcdev_mode = read_src;
 358         WARN_ON(!src_device);
 359         dev_replace->srcdev = src_device;
 360         WARN_ON(!tgt_device);
 361         dev_replace->tgtdev = tgt_device;
 362
 363         btrfs_info_in_rcu(fs_info,
 364                       "dev_replace from %s (devid %llu) to %s started",
 365                       src_device->missing ? "<missing disk>" :
 366                         rcu_str_deref(src_device->name),
 367                       src_device->devid,
 368                       rcu_str_deref(tgt_device->name));
 369
 370         /*
 371          * from now on, the writes to the srcdev are all duplicated to
 372          * go to the tgtdev as well (refer to btrfs_map_block()).
 373          */
 374         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 375         dev_replace->time_started = get_seconds();
 376         dev_replace->cursor_left = 0;
 377         dev_replace->committed_cursor_left = 0;
 378         dev_replace->cursor_left_last_write_of_item = 0;
 379         dev_replace->cursor_right = 0;
 380         dev_replace->is_valid = 1;
 381         dev_replace->item_needs_writeback = 1;
 382         atomic64_set(&dev_replace->num_write_errors, 0);
 383         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 384         btrfs_dev_replace_unlock(dev_replace, 1);
 385
 386         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 387         if (ret)
 388                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 389
 390         btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
 391
 392         /* force writing the updated state information to disk */
 393         trans = btrfs_start_transaction(root, 0);
 394         if (IS_ERR(trans)) {
 395                 ret = PTR_ERR(trans);
 396                 btrfs_dev_replace_lock(dev_replace, 1);
 397                 goto leave;
 398         }
 399
 400         ret = btrfs_commit_transaction(trans);
 401         WARN_ON(ret);
 402
 403         /* the disk copy procedure reuses the scrub code */
 404         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 405                               btrfs_device_get_total_bytes(src_device),
 406                               &dev_replace->scrub_progress, 0, 1);
 407
 408         ret = btrfs_dev_replace_finishing(fs_info, ret);
 409         if (ret == -EINPROGRESS) {
 410                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 411         } else {
 412                 WARN_ON(ret);
 413         }
 414
 415         return ret;
 416
 417 leave:
 418         dev_replace->srcdev = NULL;
 419         dev_replace->tgtdev = NULL;
 420         btrfs_dev_replace_unlock(dev_replace, 1);
 421         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 422         return ret;
 423 }
 424
 425 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 426                             struct btrfs_ioctl_dev_replace_args *args)
 427 {
 428         int ret;
 429
 430         switch (args->start.cont_reading_from_srcdev_mode) {
 431         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 432         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 433                 break;
 434         default:
 435                 return -EINVAL;
 436         }
 437
 438         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 439             args->start.tgtdev_name[0] == '\0')
 440                 return -EINVAL;
 441
 442         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 443                                         args->start.srcdevid,
 444                                         args->start.srcdev_name,
 445                                         args->start.cont_reading_from_srcdev_mode);
 446         args->result = ret;
 447         /* don't warn if EINPROGRESS, someone else might be running scrub */
 448         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
 449                 ret = 0;
 450
 451         return ret;
 452 }
 453
 454 /*
 455  * blocked until all in-flight bios operations are finished.
 456  */
 457 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 458 {
 459         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 460         wait_event(fs_info->replace_wait, !percpu_counter_sum(
 461                    &fs_info->bio_counter));
 462 }
 463
 464 /*
 465  * we have removed target device, it is safe to allow new bios request.
 466  */
 467 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 468 {
 469         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 470         wake_up(&fs_info->replace_wait);
 471 }
 472
 473 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 474                                        int scrub_ret)
 475 {
 476         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 477         struct btrfs_device *tgt_device;
 478         struct btrfs_device *src_device;
 479         struct btrfs_root *root = fs_info->tree_root;
 480         u8 uuid_tmp[BTRFS_UUID_SIZE];
 481         struct btrfs_trans_handle *trans;
 482         int ret = 0;
 483
 484         /* don't allow cancel or unmount to disturb the finishing procedure */
 485         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 486
 487         btrfs_dev_replace_lock(dev_replace, 0);
 488         /* was the operation canceled, or is it finished? */
 489         if (dev_replace->replace_state !=
 490             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 491                 btrfs_dev_replace_unlock(dev_replace, 0);
 492                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 493                 return 0;
 494         }
 495
 496         tgt_device = dev_replace->tgtdev;
 497         src_device = dev_replace->srcdev;
 498         btrfs_dev_replace_unlock(dev_replace, 0);
 499
 500         /*
 501          * flush all outstanding I/O and inode extent mappings before the
 502          * copy operation is declared as being finished
 503          */
 504         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
 505         if (ret) {
 506                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 507                 return ret;
 508         }
 509         btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
 510
 511         trans = btrfs_start_transaction(root, 0);
 512         if (IS_ERR(trans)) {
 513                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 514                 return PTR_ERR(trans);
 515         }
 516         ret = btrfs_commit_transaction(trans);
 517         WARN_ON(ret);
 518
 519         mutex_lock(&uuid_mutex);
 520         /* keep away write_all_supers() during the finishing procedure */
 521         mutex_lock(&fs_info->fs_devices->device_list_mutex);
 522         mutex_lock(&fs_info->chunk_mutex);
 523         btrfs_dev_replace_lock(dev_replace, 1);
 524         dev_replace->replace_state =
 525                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 526                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 527         dev_replace->tgtdev = NULL;
 528         dev_replace->srcdev = NULL;
 529         dev_replace->time_stopped = get_seconds();
 530         dev_replace->item_needs_writeback = 1;
 531
 532         /* replace old device with new one in mapping tree */
 533         if (!scrub_ret) {
 534                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 535                                                                 src_device,
 536                                                                 tgt_device);
 537         } else {
 538                 btrfs_err_in_rcu(fs_info,
 539                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 540                                  src_device->missing ? "<missing disk>" :
 541                                  rcu_str_deref(src_device->name),
 542                                  src_device->devid,
 543                                  rcu_str_deref(tgt_device->name), scrub_ret);
 544                 btrfs_dev_replace_unlock(dev_replace, 1);
 545                 mutex_unlock(&fs_info->chunk_mutex);
 546                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 547                 mutex_unlock(&uuid_mutex);
 548                 if (tgt_device)
 549                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 550                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 551
 552                 return scrub_ret;
 553         }
 554
 555         btrfs_info_in_rcu(fs_info,
 556                           "dev_replace from %s (devid %llu) to %s finished",
 557                           src_device->missing ? "<missing disk>" :
 558                           rcu_str_deref(src_device->name),
 559                           src_device->devid,
 560                           rcu_str_deref(tgt_device->name));
 561         tgt_device->is_tgtdev_for_dev_replace = 0;
 562         tgt_device->devid = src_device->devid;
 563         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 564         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 565         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 566         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 567         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 568         btrfs_device_set_disk_total_bytes(tgt_device,
 569                                           src_device->disk_total_bytes);
 570         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 571         ASSERT(list_empty(&src_device->resized_list));
 572         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
 573         tgt_device->commit_bytes_used = src_device->bytes_used;
 574
 575         btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
 576
 577         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 578         fs_info->fs_devices->rw_devices++;
 579
 580         btrfs_dev_replace_unlock(dev_replace, 1);
 581
 582         btrfs_rm_dev_replace_blocked(fs_info);
 583
 584         btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
 585
 586         btrfs_rm_dev_replace_unblocked(fs_info);
 587
 588         /*
 589          * this is again a consistent state where no dev_replace procedure
 590          * is running, the target device is part of the filesystem, the
 591          * source device is not part of the filesystem anymore and its 1st
 592          * superblock is scratched out so that it is no longer marked to
 593          * belong to this filesystem.
 594          */
 595         mutex_unlock(&fs_info->chunk_mutex);
 596         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 597         mutex_unlock(&uuid_mutex);
 598
 599         /* replace the sysfs entry */
 600         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
 601         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 602
 603         /* write back the superblocks */
 604         trans = btrfs_start_transaction(root, 0);
 605         if (!IS_ERR(trans))
 606                 btrfs_commit_transaction(trans);
 607
 608         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 609
 610         return 0;
 611 }
 612
 613 static void btrfs_dev_replace_update_device_in_mapping_tree(
 614                                                 struct btrfs_fs_info *fs_info,
 615                                                 struct btrfs_device *srcdev,
 616                                                 struct btrfs_device *tgtdev)
 617 {
 618         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 619         struct extent_map *em;
 620         struct map_lookup *map;
 621         u64 start = 0;
 622         int i;
 623
 624         write_lock(&em_tree->lock);
 625         do {
 626                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 627                 if (!em)
 628                         break;
 629                 map = em->map_lookup;
 630                 for (i = 0; i < map->num_stripes; i++)
 631                         if (srcdev == map->stripes[i].dev)
 632                                 map->stripes[i].dev = tgtdev;
 633                 start = em->start + em->len;
 634                 free_extent_map(em);
 635         } while (start);
 636         write_unlock(&em_tree->lock);
 637 }
 638
 639 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 640                               struct btrfs_ioctl_dev_replace_args *args)
 641 {
 642         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 643         struct btrfs_device *srcdev;
 644
 645         btrfs_dev_replace_lock(dev_replace, 0);
 646         /* even if !dev_replace_is_valid, the values are good enough for
 647          * the replace_status ioctl */
 648         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 649         args->status.replace_state = dev_replace->replace_state;
 650         args->status.time_started = dev_replace->time_started;
 651         args->status.time_stopped = dev_replace->time_stopped;
 652         args->status.num_write_errors =
 653                 atomic64_read(&dev_replace->num_write_errors);
 654         args->status.num_uncorrectable_read_errors =
 655                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 656         switch (dev_replace->replace_state) {
 657         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 658         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 659                 args->status.progress_1000 = 0;
 660                 break;
 661         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 662                 args->status.progress_1000 = 1000;
 663                 break;
 664         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 665         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 666                 srcdev = dev_replace->srcdev;
 667                 args->status.progress_1000 = div_u64(dev_replace->cursor_left,
 668                         div_u64(btrfs_device_get_total_bytes(srcdev), 1000));
 669                 break;
 670         }
 671         btrfs_dev_replace_unlock(dev_replace, 0);
 672 }
 673
 674 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 675                              struct btrfs_ioctl_dev_replace_args *args)
 676 {
 677         args->result = __btrfs_dev_replace_cancel(fs_info);
 678         return 0;
 679 }
 680
 681 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 682 {
 683         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 684         struct btrfs_device *tgt_device = NULL;
 685         struct btrfs_trans_handle *trans;
 686         struct btrfs_root *root = fs_info->tree_root;
 687         u64 result;
 688         int ret;
 689
 690         if (fs_info->sb->s_flags & MS_RDONLY)
 691                 return -EROFS;
 692
 693         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 694         btrfs_dev_replace_lock(dev_replace, 1);
 695         switch (dev_replace->replace_state) {
 696         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 697         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 698         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 699                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 700                 btrfs_dev_replace_unlock(dev_replace, 1);
 701                 goto leave;
 702         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 703         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 704                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 705                 tgt_device = dev_replace->tgtdev;
 706                 dev_replace->tgtdev = NULL;
 707                 dev_replace->srcdev = NULL;
 708                 break;
 709         }
 710         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 711         dev_replace->time_stopped = get_seconds();
 712         dev_replace->item_needs_writeback = 1;
 713         btrfs_dev_replace_unlock(dev_replace, 1);
 714         btrfs_scrub_cancel(fs_info);
 715
 716         trans = btrfs_start_transaction(root, 0);
 717         if (IS_ERR(trans)) {
 718                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 719                 return PTR_ERR(trans);
 720         }
 721         ret = btrfs_commit_transaction(trans);
 722         WARN_ON(ret);
 723         if (tgt_device)
 724                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 725
 726 leave:
 727         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 728         return result;
 729 }
 730
 731 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 732 {
 733         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 734
 735         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 736         btrfs_dev_replace_lock(dev_replace, 1);
 737         switch (dev_replace->replace_state) {
 738         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 739         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 740         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 741         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 742                 break;
 743         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 744                 dev_replace->replace_state =
 745                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 746                 dev_replace->time_stopped = get_seconds();
 747                 dev_replace->item_needs_writeback = 1;
 748                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 749                 break;
 750         }
 751
 752         btrfs_dev_replace_unlock(dev_replace, 1);
 753         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 754 }
 755
 756 /* resume dev_replace procedure that was interrupted by unmount */
 757 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 758 {
 759         struct task_struct *task;
 760         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 761
 762         btrfs_dev_replace_lock(dev_replace, 1);
 763         switch (dev_replace->replace_state) {
 764         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 765         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 766         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 767                 btrfs_dev_replace_unlock(dev_replace, 1);
 768                 return 0;
 769         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 770                 break;
 771         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 772                 dev_replace->replace_state =
 773                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 774                 break;
 775         }
 776         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 777                 btrfs_info(fs_info,
 778                            "cannot continue dev_replace, tgtdev is missing");
 779                 btrfs_info(fs_info,
 780                            "you may cancel the operation after 'mount -o degraded'");
 781                 btrfs_dev_replace_unlock(dev_replace, 1);
 782                 return 0;
 783         }
 784         btrfs_dev_replace_unlock(dev_replace, 1);
 785
 786         WARN_ON(atomic_xchg(
 787                 &fs_info->mutually_exclusive_operation_running, 1));
 788         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 789         return PTR_ERR_OR_ZERO(task);
 790 }
 791
 792 static int btrfs_dev_replace_kthread(void *data)
 793 {
 794         struct btrfs_fs_info *fs_info = data;
 795         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 796         struct btrfs_ioctl_dev_replace_args *status_args;
 797         u64 progress;
 798
 799         status_args = kzalloc(sizeof(*status_args), GFP_KERNEL);
 800         if (status_args) {
 801                 btrfs_dev_replace_status(fs_info, status_args);
 802                 progress = status_args->status.progress_1000;
 803                 kfree(status_args);
 804                 progress = div_u64(progress, 10);
 805                 btrfs_info_in_rcu(fs_info,
 806                         "continuing dev_replace from %s (devid %llu) to %s @%u%%",
 807                         dev_replace->srcdev->missing ? "<missing disk>" :
 808                         rcu_str_deref(dev_replace->srcdev->name),
 809                         dev_replace->srcdev->devid,
 810                         dev_replace->tgtdev ?
 811                         rcu_str_deref(dev_replace->tgtdev->name) :
 812                         "<missing target disk>",
 813                         (unsigned int)progress);
 814         }
 815         btrfs_dev_replace_continue_on_mount(fs_info);
 816         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
 817
 818         return 0;
 819 }
 820
 821 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 822 {
 823         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 824         int ret;
 825
 826         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 827                               dev_replace->committed_cursor_left,
 828                               btrfs_device_get_total_bytes(dev_replace->srcdev),
 829                               &dev_replace->scrub_progress, 0, 1);
 830         ret = btrfs_dev_replace_finishing(fs_info, ret);
 831         WARN_ON(ret);
 832         return 0;
 833 }
 834
 835 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 836 {
 837         if (!dev_replace->is_valid)
 838                 return 0;
 839
 840         switch (dev_replace->replace_state) {
 841         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 842         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 843         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 844                 return 0;
 845         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 846         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 847                 /*
 848                  * return true even if tgtdev is missing (this is
 849                  * something that can happen if the dev_replace
 850                  * procedure is suspended by an umount and then
 851                  * the tgtdev is missing (or "btrfs dev scan") was
 852                  * not called and the the filesystem is remounted
 853                  * in degraded state. This does not stop the
 854                  * dev_replace procedure. It needs to be canceled
 855                  * manually if the cancellation is wanted.
 856                  */
 857                 break;
 858         }
 859         return 1;
 860 }
 861
 862 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
 863 {
 864         if (rw == 1) {
 865                 /* write */
 866 again:
 867                 wait_event(dev_replace->read_lock_wq,
 868                            atomic_read(&dev_replace->blocking_readers) == 0);
 869                 write_lock(&dev_replace->lock);
 870                 if (atomic_read(&dev_replace->blocking_readers)) {
 871                         write_unlock(&dev_replace->lock);
 872                         goto again;
 873                 }
 874         } else {
 875                 read_lock(&dev_replace->lock);
 876                 atomic_inc(&dev_replace->read_locks);
 877         }
 878 }
 879
 880 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
 881 {
 882         if (rw == 1) {
 883                 /* write */
 884                 ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
 885                 write_unlock(&dev_replace->lock);
 886         } else {
 887                 ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 888                 atomic_dec(&dev_replace->read_locks);
 889                 read_unlock(&dev_replace->lock);
 890         }
 891 }
 892
 893 /* inc blocking cnt and release read lock */
 894 void btrfs_dev_replace_set_lock_blocking(
 895                                         struct btrfs_dev_replace *dev_replace)
 896 {
 897         /* only set blocking for read lock */
 898         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 899         atomic_inc(&dev_replace->blocking_readers);
 900         read_unlock(&dev_replace->lock);
 901 }
 902
 903 /* acquire read lock and dec blocking cnt */
 904 void btrfs_dev_replace_clear_lock_blocking(
 905                                         struct btrfs_dev_replace *dev_replace)
 906 {
 907         /* only set blocking for read lock */
 908         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
 909         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
 910         read_lock(&dev_replace->lock);
 911         if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
 912             waitqueue_active(&dev_replace->read_lock_wq))
 913                 wake_up(&dev_replace->read_lock_wq);
 914 }
 915
 916 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
 917 {
 918         percpu_counter_inc(&fs_info->bio_counter);
 919 }
 920
 921 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
 922 {
 923         percpu_counter_sub(&fs_info->bio_counter, amount);
 924
 925         if (waitqueue_active(&fs_info->replace_wait))
 926                 wake_up(&fs_info->replace_wait);
 927 }
 928
 929 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
 930 {
 931         while (1) {
 932                 percpu_counter_inc(&fs_info->bio_counter);
 933                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 934                                      &fs_info->fs_state)))
 935                         break;
 936
 937                 btrfs_bio_counter_dec(fs_info);
 938                 wait_event(fs_info->replace_wait,
 939                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 940                                      &fs_info->fs_state));
 941         }
 942 }