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
  40 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
  41                                        int scrub_ret);
  42 static void btrfs_dev_replace_update_device_in_mapping_tree(
  43                                                 struct btrfs_fs_info *fs_info,
  44                                                 struct btrfs_device *srcdev,
  45                                                 struct btrfs_device *tgtdev);
  46 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
  47                                          char *srcdev_name,
  48                                          struct btrfs_device **device);
  49 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info);
  50 static int btrfs_dev_replace_kthread(void *data);
  51 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
  52
  53
  54 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  55 {
  56         struct btrfs_key key;
  57         struct btrfs_root *dev_root = fs_info->dev_root;
  58         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  59         struct extent_buffer *eb;
  60         int slot;
  61         int ret = 0;
  62         struct btrfs_path *path = NULL;
  63         int item_size;
  64         struct btrfs_dev_replace_item *ptr;
  65         u64 src_devid;
  66
  67         path = btrfs_alloc_path();
  68         if (!path) {
  69                 ret = -ENOMEM;
  70                 goto out;
  71         }
  72
  73         key.objectid = 0;
  74         key.type = BTRFS_DEV_REPLACE_KEY;
  75         key.offset = 0;
  76         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  77         if (ret) {
  78 no_valid_dev_replace_entry_found:
  79                 ret = 0;
  80                 dev_replace->replace_state =
  81                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
  82                 dev_replace->cont_reading_from_srcdev_mode =
  83                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
  84                 dev_replace->replace_state = 0;
  85                 dev_replace->time_started = 0;
  86                 dev_replace->time_stopped = 0;
  87                 atomic64_set(&dev_replace->num_write_errors, 0);
  88                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
  89                 dev_replace->cursor_left = 0;
  90                 dev_replace->committed_cursor_left = 0;
  91                 dev_replace->cursor_left_last_write_of_item = 0;
  92                 dev_replace->cursor_right = 0;
  93                 dev_replace->srcdev = NULL;
  94                 dev_replace->tgtdev = NULL;
  95                 dev_replace->is_valid = 0;
  96                 dev_replace->item_needs_writeback = 0;
  97                 goto out;
  98         }
  99         slot = path->slots[0];
 100         eb = path->nodes[0];
 101         item_size = btrfs_item_size_nr(eb, slot);
 102         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
 103
 104         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
 105                 pr_warn("btrfs: dev_replace entry found has unexpected size, ignore entry\n");
 106                 goto no_valid_dev_replace_entry_found;
 107         }
 108
 109         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
 110         dev_replace->cont_reading_from_srcdev_mode =
 111                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
 112         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
 113         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
 114         dev_replace->time_stopped =
 115                 btrfs_dev_replace_time_stopped(eb, ptr);
 116         atomic64_set(&dev_replace->num_write_errors,
 117                      btrfs_dev_replace_num_write_errors(eb, ptr));
 118         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 119                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 120         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 121         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 122         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 123         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 124         dev_replace->is_valid = 1;
 125
 126         dev_replace->item_needs_writeback = 0;
 127         switch (dev_replace->replace_state) {
 128         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 129         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 130         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 131                 dev_replace->srcdev = NULL;
 132                 dev_replace->tgtdev = NULL;
 133                 break;
 134         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 135         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 136                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
 137                                                         NULL, NULL);
 138                 dev_replace->tgtdev = btrfs_find_device(fs_info,
 139                                                         BTRFS_DEV_REPLACE_DEVID,
 140                                                         NULL, NULL);
 141                 /*
 142                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 143                  * missing
 144                  */
 145                 if (!dev_replace->srcdev &&
 146                     !btrfs_test_opt(dev_root, DEGRADED)) {
 147                         ret = -EIO;
 148                         pr_warn("btrfs: cannot mount because device replace operation is ongoing and\n" "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?\n",
 149                                 src_devid);
 150                 }
 151                 if (!dev_replace->tgtdev &&
 152                     !btrfs_test_opt(dev_root, DEGRADED)) {
 153                         ret = -EIO;
 154                         pr_warn("btrfs: cannot mount because device replace operation is ongoing and\n" "tgtdev (devid %llu) is missing, need to run btrfs dev scan?\n",
 155                                 BTRFS_DEV_REPLACE_DEVID);
 156                 }
 157                 if (dev_replace->tgtdev) {
 158                         if (dev_replace->srcdev) {
 159                                 dev_replace->tgtdev->total_bytes =
 160                                         dev_replace->srcdev->total_bytes;
 161                                 dev_replace->tgtdev->disk_total_bytes =
 162                                         dev_replace->srcdev->disk_total_bytes;
 163                                 dev_replace->tgtdev->bytes_used =
 164                                         dev_replace->srcdev->bytes_used;
 165                         }
 166                         dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
 167                         btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
 168                                 dev_replace->tgtdev);
 169                 }
 170                 break;
 171         }
 172
 173 out:
 174         if (path)
 175                 btrfs_free_path(path);
 176         return ret;
 177 }
 178
 179 /*
 180  * called from commit_transaction. Writes changed device replace state to
 181  * disk.
 182  */
 183 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 184                           struct btrfs_fs_info *fs_info)
 185 {
 186         int ret;
 187         struct btrfs_root *dev_root = fs_info->dev_root;
 188         struct btrfs_path *path;
 189         struct btrfs_key key;
 190         struct extent_buffer *eb;
 191         struct btrfs_dev_replace_item *ptr;
 192         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 193
 194         btrfs_dev_replace_lock(dev_replace);
 195         if (!dev_replace->is_valid ||
 196             !dev_replace->item_needs_writeback) {
 197                 btrfs_dev_replace_unlock(dev_replace);
 198                 return 0;
 199         }
 200         btrfs_dev_replace_unlock(dev_replace);
 201
 202         key.objectid = 0;
 203         key.type = BTRFS_DEV_REPLACE_KEY;
 204         key.offset = 0;
 205
 206         path = btrfs_alloc_path();
 207         if (!path) {
 208                 ret = -ENOMEM;
 209                 goto out;
 210         }
 211         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 212         if (ret < 0) {
 213                 pr_warn("btrfs: error %d while searching for dev_replace item!\n",
 214                         ret);
 215                 goto out;
 216         }
 217
 218         if (ret == 0 &&
 219             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 220                 /*
 221                  * need to delete old one and insert a new one.
 222                  * Since no attempt is made to recover any old state, if the
 223                  * dev_replace state is 'running', the data on the target
 224                  * drive is lost.
 225                  * It would be possible to recover the state: just make sure
 226                  * that the beginning of the item is never changed and always
 227                  * contains all the essential information. Then read this
 228                  * minimal set of information and use it as a base for the
 229                  * new state.
 230                  */
 231                 ret = btrfs_del_item(trans, dev_root, path);
 232                 if (ret != 0) {
 233                         pr_warn("btrfs: delete too small dev_replace item failed %d!\n",
 234                                 ret);
 235                         goto out;
 236                 }
 237                 ret = 1;
 238         }
 239
 240         if (ret == 1) {
 241                 /* need to insert a new item */
 242                 btrfs_release_path(path);
 243                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 244                                               &key, sizeof(*ptr));
 245                 if (ret < 0) {
 246                         pr_warn("btrfs: insert dev_replace item failed %d!\n",
 247                                 ret);
 248                         goto out;
 249                 }
 250         }
 251
 252         eb = path->nodes[0];
 253         ptr = btrfs_item_ptr(eb, path->slots[0],
 254                              struct btrfs_dev_replace_item);
 255
 256         btrfs_dev_replace_lock(dev_replace);
 257         if (dev_replace->srcdev)
 258                 btrfs_set_dev_replace_src_devid(eb, ptr,
 259                         dev_replace->srcdev->devid);
 260         else
 261                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 262         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 263                 dev_replace->cont_reading_from_srcdev_mode);
 264         btrfs_set_dev_replace_replace_state(eb, ptr,
 265                 dev_replace->replace_state);
 266         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 267         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 268         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 269                 atomic64_read(&dev_replace->num_write_errors));
 270         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 271                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 272         dev_replace->cursor_left_last_write_of_item =
 273                 dev_replace->cursor_left;
 274         btrfs_set_dev_replace_cursor_left(eb, ptr,
 275                 dev_replace->cursor_left_last_write_of_item);
 276         btrfs_set_dev_replace_cursor_right(eb, ptr,
 277                 dev_replace->cursor_right);
 278         dev_replace->item_needs_writeback = 0;
 279         btrfs_dev_replace_unlock(dev_replace);
 280
 281         btrfs_mark_buffer_dirty(eb);
 282
 283 out:
 284         btrfs_free_path(path);
 285
 286         return ret;
 287 }
 288
 289 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 290 {
 291         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 292
 293         dev_replace->committed_cursor_left =
 294                 dev_replace->cursor_left_last_write_of_item;
 295 }
 296
 297 int btrfs_dev_replace_start(struct btrfs_root *root,
 298                             struct btrfs_ioctl_dev_replace_args *args)
 299 {
 300         struct btrfs_trans_handle *trans;
 301         struct btrfs_fs_info *fs_info = root->fs_info;
 302         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 303         int ret;
 304         struct btrfs_device *tgt_device = NULL;
 305         struct btrfs_device *src_device = NULL;
 306
 307         if (btrfs_fs_incompat(fs_info, RAID56)) {
 308                 pr_warn("btrfs: dev_replace cannot yet handle RAID5/RAID6\n");
 309                 return -EINVAL;
 310         }
 311
 312         switch (args->start.cont_reading_from_srcdev_mode) {
 313         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 314         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 315                 break;
 316         default:
 317                 return -EINVAL;
 318         }
 319
 320         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 321             args->start.tgtdev_name[0] == '\0')
 322                 return -EINVAL;
 323
 324         mutex_lock(&fs_info->volume_mutex);
 325         ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
 326                                             &tgt_device);
 327         if (ret) {
 328                 pr_err("btrfs: target device %s is invalid!\n",
 329                        args->start.tgtdev_name);
 330                 mutex_unlock(&fs_info->volume_mutex);
 331                 return -EINVAL;
 332         }
 333
 334         ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
 335                                             args->start.srcdev_name,
 336                                             &src_device);
 337         mutex_unlock(&fs_info->volume_mutex);
 338         if (ret) {
 339                 ret = -EINVAL;
 340                 goto leave_no_lock;
 341         }
 342
 343         if (tgt_device->total_bytes < src_device->total_bytes) {
 344                 pr_err("btrfs: target device is smaller than source device!\n");
 345                 ret = -EINVAL;
 346                 goto leave_no_lock;
 347         }
 348
 349         btrfs_dev_replace_lock(dev_replace);
 350         switch (dev_replace->replace_state) {
 351         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 352         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 353         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 354                 break;
 355         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 356         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 357                 args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 358                 goto leave;
 359         }
 360
 361         dev_replace->cont_reading_from_srcdev_mode =
 362                 args->start.cont_reading_from_srcdev_mode;
 363         WARN_ON(!src_device);
 364         dev_replace->srcdev = src_device;
 365         WARN_ON(!tgt_device);
 366         dev_replace->tgtdev = tgt_device;
 367
 368         printk_in_rcu(KERN_INFO
 369                       "btrfs: dev_replace from %s (devid %llu) to %s started\n",
 370                       src_device->missing ? "<missing disk>" :
 371                         rcu_str_deref(src_device->name),
 372                       src_device->devid,
 373                       rcu_str_deref(tgt_device->name));
 374
 375         tgt_device->total_bytes = src_device->total_bytes;
 376         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
 377         tgt_device->bytes_used = src_device->bytes_used;
 378
 379         /*
 380          * from now on, the writes to the srcdev are all duplicated to
 381          * go to the tgtdev as well (refer to btrfs_map_block()).
 382          */
 383         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 384         dev_replace->time_started = get_seconds();
 385         dev_replace->cursor_left = 0;
 386         dev_replace->committed_cursor_left = 0;
 387         dev_replace->cursor_left_last_write_of_item = 0;
 388         dev_replace->cursor_right = 0;
 389         dev_replace->is_valid = 1;
 390         dev_replace->item_needs_writeback = 1;
 391         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 392         btrfs_dev_replace_unlock(dev_replace);
 393
 394         btrfs_wait_ordered_roots(root->fs_info, -1);
 395
 396         /* force writing the updated state information to disk */
 397         trans = btrfs_start_transaction(root, 0);
 398         if (IS_ERR(trans)) {
 399                 ret = PTR_ERR(trans);
 400                 btrfs_dev_replace_lock(dev_replace);
 401                 goto leave;
 402         }
 403
 404         ret = btrfs_commit_transaction(trans, root);
 405         WARN_ON(ret);
 406
 407         /* the disk copy procedure reuses the scrub code */
 408         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 409                               src_device->total_bytes,
 410                               &dev_replace->scrub_progress, 0, 1);
 411
 412         ret = btrfs_dev_replace_finishing(root->fs_info, ret);
 413         WARN_ON(ret);
 414
 415         return 0;
 416
 417 leave:
 418         dev_replace->srcdev = NULL;
 419         dev_replace->tgtdev = NULL;
 420         btrfs_dev_replace_unlock(dev_replace);
 421 leave_no_lock:
 422         if (tgt_device)
 423                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 424         return ret;
 425 }
 426
 427 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 428                                        int scrub_ret)
 429 {
 430         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 431         struct btrfs_device *tgt_device;
 432         struct btrfs_device *src_device;
 433         struct btrfs_root *root = fs_info->tree_root;
 434         u8 uuid_tmp[BTRFS_UUID_SIZE];
 435         struct btrfs_trans_handle *trans;
 436         int ret = 0;
 437
 438         /* don't allow cancel or unmount to disturb the finishing procedure */
 439         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 440
 441         btrfs_dev_replace_lock(dev_replace);
 442         /* was the operation canceled, or is it finished? */
 443         if (dev_replace->replace_state !=
 444             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 445                 btrfs_dev_replace_unlock(dev_replace);
 446                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 447                 return 0;
 448         }
 449
 450         tgt_device = dev_replace->tgtdev;
 451         src_device = dev_replace->srcdev;
 452         btrfs_dev_replace_unlock(dev_replace);
 453
 454         /* replace old device with new one in mapping tree */
 455         if (!scrub_ret)
 456                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 457                                                                 src_device,
 458                                                                 tgt_device);
 459
 460         /*
 461          * flush all outstanding I/O and inode extent mappings before the
 462          * copy operation is declared as being finished
 463          */
 464         ret = btrfs_start_delalloc_roots(root->fs_info, 0);
 465         if (ret) {
 466                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 467                 return ret;
 468         }
 469         btrfs_wait_ordered_roots(root->fs_info, -1);
 470
 471         trans = btrfs_start_transaction(root, 0);
 472         if (IS_ERR(trans)) {
 473                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 474                 return PTR_ERR(trans);
 475         }
 476         ret = btrfs_commit_transaction(trans, root);
 477         WARN_ON(ret);
 478
 479         /* keep away write_all_supers() during the finishing procedure */
 480         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
 481         btrfs_dev_replace_lock(dev_replace);
 482         dev_replace->replace_state =
 483                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 484                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 485         dev_replace->tgtdev = NULL;
 486         dev_replace->srcdev = NULL;
 487         dev_replace->time_stopped = get_seconds();
 488         dev_replace->item_needs_writeback = 1;
 489
 490         if (scrub_ret) {
 491                 printk_in_rcu(KERN_ERR
 492                               "btrfs: btrfs_scrub_dev(%s, %llu, %s) failed %d\n",
 493                               src_device->missing ? "<missing disk>" :
 494                                 rcu_str_deref(src_device->name),
 495                               src_device->devid,
 496                               rcu_str_deref(tgt_device->name), scrub_ret);
 497                 btrfs_dev_replace_unlock(dev_replace);
 498                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 499                 if (tgt_device)
 500                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 501                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 502
 503                 return 0;
 504         }
 505
 506         printk_in_rcu(KERN_INFO
 507                       "btrfs: dev_replace from %s (devid %llu) to %s) finished\n",
 508                       src_device->missing ? "<missing disk>" :
 509                         rcu_str_deref(src_device->name),
 510                       src_device->devid,
 511                       rcu_str_deref(tgt_device->name));
 512         tgt_device->is_tgtdev_for_dev_replace = 0;
 513         tgt_device->devid = src_device->devid;
 514         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 515         tgt_device->bytes_used = src_device->bytes_used;
 516         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 517         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 518         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 519         tgt_device->total_bytes = src_device->total_bytes;
 520         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
 521         tgt_device->bytes_used = src_device->bytes_used;
 522         if (fs_info->sb->s_bdev == src_device->bdev)
 523                 fs_info->sb->s_bdev = tgt_device->bdev;
 524         if (fs_info->fs_devices->latest_bdev == src_device->bdev)
 525                 fs_info->fs_devices->latest_bdev = tgt_device->bdev;
 526         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 527
 528         btrfs_rm_dev_replace_srcdev(fs_info, src_device);
 529
 530         /*
 531          * this is again a consistent state where no dev_replace procedure
 532          * is running, the target device is part of the filesystem, the
 533          * source device is not part of the filesystem anymore and its 1st
 534          * superblock is scratched out so that it is no longer marked to
 535          * belong to this filesystem.
 536          */
 537         btrfs_dev_replace_unlock(dev_replace);
 538         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 539
 540         /* write back the superblocks */
 541         trans = btrfs_start_transaction(root, 0);
 542         if (!IS_ERR(trans))
 543                 btrfs_commit_transaction(trans, root);
 544
 545         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 546
 547         return 0;
 548 }
 549
 550 static void btrfs_dev_replace_update_device_in_mapping_tree(
 551                                                 struct btrfs_fs_info *fs_info,
 552                                                 struct btrfs_device *srcdev,
 553                                                 struct btrfs_device *tgtdev)
 554 {
 555         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 556         struct extent_map *em;
 557         struct map_lookup *map;
 558         u64 start = 0;
 559         int i;
 560
 561         write_lock(&em_tree->lock);
 562         do {
 563                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 564                 if (!em)
 565                         break;
 566                 map = (struct map_lookup *)em->bdev;
 567                 for (i = 0; i < map->num_stripes; i++)
 568                         if (srcdev == map->stripes[i].dev)
 569                                 map->stripes[i].dev = tgtdev;
 570                 start = em->start + em->len;
 571                 free_extent_map(em);
 572         } while (start);
 573         write_unlock(&em_tree->lock);
 574 }
 575
 576 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
 577                                          char *srcdev_name,
 578                                          struct btrfs_device **device)
 579 {
 580         int ret;
 581
 582         if (srcdevid) {
 583                 ret = 0;
 584                 *device = btrfs_find_device(root->fs_info, srcdevid, NULL,
 585                                             NULL);
 586                 if (!*device)
 587                         ret = -ENOENT;
 588         } else {
 589                 ret = btrfs_find_device_missing_or_by_path(root, srcdev_name,
 590                                                            device);
 591         }
 592         return ret;
 593 }
 594
 595 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 596                               struct btrfs_ioctl_dev_replace_args *args)
 597 {
 598         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 599
 600         btrfs_dev_replace_lock(dev_replace);
 601         /* even if !dev_replace_is_valid, the values are good enough for
 602          * the replace_status ioctl */
 603         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 604         args->status.replace_state = dev_replace->replace_state;
 605         args->status.time_started = dev_replace->time_started;
 606         args->status.time_stopped = dev_replace->time_stopped;
 607         args->status.num_write_errors =
 608                 atomic64_read(&dev_replace->num_write_errors);
 609         args->status.num_uncorrectable_read_errors =
 610                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 611         switch (dev_replace->replace_state) {
 612         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 613         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 614                 args->status.progress_1000 = 0;
 615                 break;
 616         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 617                 args->status.progress_1000 = 1000;
 618                 break;
 619         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 620         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 621                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
 622                         div64_u64(dev_replace->srcdev->total_bytes, 1000));
 623                 break;
 624         }
 625         btrfs_dev_replace_unlock(dev_replace);
 626 }
 627
 628 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 629                              struct btrfs_ioctl_dev_replace_args *args)
 630 {
 631         args->result = __btrfs_dev_replace_cancel(fs_info);
 632         return 0;
 633 }
 634
 635 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 636 {
 637         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 638         struct btrfs_device *tgt_device = NULL;
 639         struct btrfs_trans_handle *trans;
 640         struct btrfs_root *root = fs_info->tree_root;
 641         u64 result;
 642         int ret;
 643
 644         if (fs_info->sb->s_flags & MS_RDONLY)
 645                 return -EROFS;
 646
 647         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 648         btrfs_dev_replace_lock(dev_replace);
 649         switch (dev_replace->replace_state) {
 650         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 651         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 652         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 653                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 654                 btrfs_dev_replace_unlock(dev_replace);
 655                 goto leave;
 656         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 657         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 658                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 659                 tgt_device = dev_replace->tgtdev;
 660                 dev_replace->tgtdev = NULL;
 661                 dev_replace->srcdev = NULL;
 662                 break;
 663         }
 664         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 665         dev_replace->time_stopped = get_seconds();
 666         dev_replace->item_needs_writeback = 1;
 667         btrfs_dev_replace_unlock(dev_replace);
 668         btrfs_scrub_cancel(fs_info);
 669
 670         trans = btrfs_start_transaction(root, 0);
 671         if (IS_ERR(trans)) {
 672                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 673                 return PTR_ERR(trans);
 674         }
 675         ret = btrfs_commit_transaction(trans, root);
 676         WARN_ON(ret);
 677         if (tgt_device)
 678                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 679
 680 leave:
 681         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 682         return result;
 683 }
 684
 685 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 686 {
 687         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 688
 689         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 690         btrfs_dev_replace_lock(dev_replace);
 691         switch (dev_replace->replace_state) {
 692         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 693         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 694         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 695         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 696                 break;
 697         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 698                 dev_replace->replace_state =
 699                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 700                 dev_replace->time_stopped = get_seconds();
 701                 dev_replace->item_needs_writeback = 1;
 702                 pr_info("btrfs: suspending dev_replace for unmount\n");
 703                 break;
 704         }
 705
 706         btrfs_dev_replace_unlock(dev_replace);
 707         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 708 }
 709
 710 /* resume dev_replace procedure that was interrupted by unmount */
 711 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 712 {
 713         struct task_struct *task;
 714         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 715
 716         btrfs_dev_replace_lock(dev_replace);
 717         switch (dev_replace->replace_state) {
 718         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 719         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 720         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 721                 btrfs_dev_replace_unlock(dev_replace);
 722                 return 0;
 723         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 724                 break;
 725         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 726                 dev_replace->replace_state =
 727                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 728                 break;
 729         }
 730         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 731                 pr_info("btrfs: cannot continue dev_replace, tgtdev is missing\n"
 732                         "btrfs: you may cancel the operation after 'mount -o degraded'\n");
 733                 btrfs_dev_replace_unlock(dev_replace);
 734                 return 0;
 735         }
 736         btrfs_dev_replace_unlock(dev_replace);
 737
 738         WARN_ON(atomic_xchg(
 739                 &fs_info->mutually_exclusive_operation_running, 1));
 740         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 741         return PTR_ERR_OR_ZERO(task);
 742 }
 743
 744 static int btrfs_dev_replace_kthread(void *data)
 745 {
 746         struct btrfs_fs_info *fs_info = data;
 747         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 748         struct btrfs_ioctl_dev_replace_args *status_args;
 749         u64 progress;
 750
 751         status_args = kzalloc(sizeof(*status_args), GFP_NOFS);
 752         if (status_args) {
 753                 btrfs_dev_replace_status(fs_info, status_args);
 754                 progress = status_args->status.progress_1000;
 755                 kfree(status_args);
 756                 do_div(progress, 10);
 757                 printk_in_rcu(KERN_INFO
 758                               "btrfs: continuing dev_replace from %s (devid %llu) to %s @%u%%\n",
 759                               dev_replace->srcdev->missing ? "<missing disk>" :
 760                                 rcu_str_deref(dev_replace->srcdev->name),
 761                               dev_replace->srcdev->devid,
 762                               dev_replace->tgtdev ?
 763                                 rcu_str_deref(dev_replace->tgtdev->name) :
 764                                 "<missing target disk>",
 765                               (unsigned int)progress);
 766         }
 767         btrfs_dev_replace_continue_on_mount(fs_info);
 768         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
 769
 770         return 0;
 771 }
 772
 773 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 774 {
 775         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 776         int ret;
 777
 778         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 779                               dev_replace->committed_cursor_left,
 780                               dev_replace->srcdev->total_bytes,
 781                               &dev_replace->scrub_progress, 0, 1);
 782         ret = btrfs_dev_replace_finishing(fs_info, ret);
 783         WARN_ON(ret);
 784         return 0;
 785 }
 786
 787 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 788 {
 789         if (!dev_replace->is_valid)
 790                 return 0;
 791
 792         switch (dev_replace->replace_state) {
 793         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 794         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 795         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 796                 return 0;
 797         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 798         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 799                 /*
 800                  * return true even if tgtdev is missing (this is
 801                  * something that can happen if the dev_replace
 802                  * procedure is suspended by an umount and then
 803                  * the tgtdev is missing (or "btrfs dev scan") was
 804                  * not called and the the filesystem is remounted
 805                  * in degraded state. This does not stop the
 806                  * dev_replace procedure. It needs to be canceled
 807                  * manually if the cancelation is wanted.
 808                  */
 809                 break;
 810         }
 811         return 1;
 812 }
 813
 814 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
 815 {
 816         /* the beginning is just an optimization for the typical case */
 817         if (atomic_read(&dev_replace->nesting_level) == 0) {
 818 acquire_lock:
 819                 /* this is not a nested case where the same thread
 820                  * is trying to acqurire the same lock twice */
 821                 mutex_lock(&dev_replace->lock);
 822                 mutex_lock(&dev_replace->lock_management_lock);
 823                 dev_replace->lock_owner = current->pid;
 824                 atomic_inc(&dev_replace->nesting_level);
 825                 mutex_unlock(&dev_replace->lock_management_lock);
 826                 return;
 827         }
 828
 829         mutex_lock(&dev_replace->lock_management_lock);
 830         if (atomic_read(&dev_replace->nesting_level) > 0 &&
 831             dev_replace->lock_owner == current->pid) {
 832                 WARN_ON(!mutex_is_locked(&dev_replace->lock));
 833                 atomic_inc(&dev_replace->nesting_level);
 834                 mutex_unlock(&dev_replace->lock_management_lock);
 835                 return;
 836         }
 837
 838         mutex_unlock(&dev_replace->lock_management_lock);
 839         goto acquire_lock;
 840 }
 841
 842 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
 843 {
 844         WARN_ON(!mutex_is_locked(&dev_replace->lock));
 845         mutex_lock(&dev_replace->lock_management_lock);
 846         WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
 847         WARN_ON(dev_replace->lock_owner != current->pid);
 848         atomic_dec(&dev_replace->nesting_level);
 849         if (atomic_read(&dev_replace->nesting_level) == 0) {
 850                 dev_replace->lock_owner = 0;
 851                 mutex_unlock(&dev_replace->lock_management_lock);
 852                 mutex_unlock(&dev_replace->lock);
 853         } else {
 854                 mutex_unlock(&dev_replace->lock_management_lock);
 855         }
 856 }