Pileus Git - ~andy/linux/blob - 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                 btrfs_warn(fs_info,
 106                         "dev_replace entry found has unexpected size, ignore entry");
 107                 goto no_valid_dev_replace_entry_found;
 108         }
 109
 110         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
 111         dev_replace->cont_reading_from_srcdev_mode =
 112                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
 113         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
 114         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
 115         dev_replace->time_stopped =
 116                 btrfs_dev_replace_time_stopped(eb, ptr);
 117         atomic64_set(&dev_replace->num_write_errors,
 118                      btrfs_dev_replace_num_write_errors(eb, ptr));
 119         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 120                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 121         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 122         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 123         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 124         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 125         dev_replace->is_valid = 1;
 126
 127         dev_replace->item_needs_writeback = 0;
 128         switch (dev_replace->replace_state) {
 129         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 130         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 131         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 132                 dev_replace->srcdev = NULL;
 133                 dev_replace->tgtdev = NULL;
 134                 break;
 135         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 136         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 137                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
 138                                                         NULL, NULL);
 139                 dev_replace->tgtdev = btrfs_find_device(fs_info,
 140                                                         BTRFS_DEV_REPLACE_DEVID,
 141                                                         NULL, NULL);
 142                 /*
 143                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 144                  * missing
 145                  */
 146                 if (!dev_replace->srcdev &&
 147                     !btrfs_test_opt(dev_root, DEGRADED)) {
 148                         ret = -EIO;
 149                         btrfs_warn(fs_info,
 150                            "cannot mount because device replace operation is ongoing and");
 151                         btrfs_warn(fs_info,
 152                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 153                            src_devid);
 154                 }
 155                 if (!dev_replace->tgtdev &&
 156                     !btrfs_test_opt(dev_root, DEGRADED)) {
 157                         ret = -EIO;
 158                         btrfs_warn(fs_info,
 159                            "cannot mount because device replace operation is ongoing and");
 160                         btrfs_warn(fs_info,
 161                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 162                                 BTRFS_DEV_REPLACE_DEVID);
 163                 }
 164                 if (dev_replace->tgtdev) {
 165                         if (dev_replace->srcdev) {
 166                                 dev_replace->tgtdev->total_bytes =
 167                                         dev_replace->srcdev->total_bytes;
 168                                 dev_replace->tgtdev->disk_total_bytes =
 169                                         dev_replace->srcdev->disk_total_bytes;
 170                                 dev_replace->tgtdev->bytes_used =
 171                                         dev_replace->srcdev->bytes_used;
 172                         }
 173                         dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
 174                         btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
 175                                 dev_replace->tgtdev);
 176                 }
 177                 break;
 178         }
 179
 180 out:
 181         if (path)
 182                 btrfs_free_path(path);
 183         return ret;
 184 }
 185
 186 /*
 187  * called from commit_transaction. Writes changed device replace state to
 188  * disk.
 189  */
 190 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 191                           struct btrfs_fs_info *fs_info)
 192 {
 193         int ret;
 194         struct btrfs_root *dev_root = fs_info->dev_root;
 195         struct btrfs_path *path;
 196         struct btrfs_key key;
 197         struct extent_buffer *eb;
 198         struct btrfs_dev_replace_item *ptr;
 199         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 200
 201         btrfs_dev_replace_lock(dev_replace);
 202         if (!dev_replace->is_valid ||
 203             !dev_replace->item_needs_writeback) {
 204                 btrfs_dev_replace_unlock(dev_replace);
 205                 return 0;
 206         }
 207         btrfs_dev_replace_unlock(dev_replace);
 208
 209         key.objectid = 0;
 210         key.type = BTRFS_DEV_REPLACE_KEY;
 211         key.offset = 0;
 212
 213         path = btrfs_alloc_path();
 214         if (!path) {
 215                 ret = -ENOMEM;
 216                 goto out;
 217         }
 218         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 219         if (ret < 0) {
 220                 btrfs_warn(fs_info, "error %d while searching for dev_replace item!",
 221                         ret);
 222                 goto out;
 223         }
 224
 225         if (ret == 0 &&
 226             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 227                 /*
 228                  * need to delete old one and insert a new one.
 229                  * Since no attempt is made to recover any old state, if the
 230                  * dev_replace state is 'running', the data on the target
 231                  * drive is lost.
 232                  * It would be possible to recover the state: just make sure
 233                  * that the beginning of the item is never changed and always
 234                  * contains all the essential information. Then read this
 235                  * minimal set of information and use it as a base for the
 236                  * new state.
 237                  */
 238                 ret = btrfs_del_item(trans, dev_root, path);
 239                 if (ret != 0) {
 240                         btrfs_warn(fs_info, "delete too small dev_replace item failed %d!",
 241                                 ret);
 242                         goto out;
 243                 }
 244                 ret = 1;
 245         }
 246
 247         if (ret == 1) {
 248                 /* need to insert a new item */
 249                 btrfs_release_path(path);
 250                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 251                                               &key, sizeof(*ptr));
 252                 if (ret < 0) {
 253                         btrfs_warn(fs_info, "insert dev_replace item failed %d!",
 254                                 ret);
 255                         goto out;
 256                 }
 257         }
 258
 259         eb = path->nodes[0];
 260         ptr = btrfs_item_ptr(eb, path->slots[0],
 261                              struct btrfs_dev_replace_item);
 262
 263         btrfs_dev_replace_lock(dev_replace);
 264         if (dev_replace->srcdev)
 265                 btrfs_set_dev_replace_src_devid(eb, ptr,
 266                         dev_replace->srcdev->devid);
 267         else
 268                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 269         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 270                 dev_replace->cont_reading_from_srcdev_mode);
 271         btrfs_set_dev_replace_replace_state(eb, ptr,
 272                 dev_replace->replace_state);
 273         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 274         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 275         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 276                 atomic64_read(&dev_replace->num_write_errors));
 277         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 278                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 279         dev_replace->cursor_left_last_write_of_item =
 280                 dev_replace->cursor_left;
 281         btrfs_set_dev_replace_cursor_left(eb, ptr,
 282                 dev_replace->cursor_left_last_write_of_item);
 283         btrfs_set_dev_replace_cursor_right(eb, ptr,
 284                 dev_replace->cursor_right);
 285         dev_replace->item_needs_writeback = 0;
 286         btrfs_dev_replace_unlock(dev_replace);
 287
 288         btrfs_mark_buffer_dirty(eb);
 289
 290 out:
 291         btrfs_free_path(path);
 292
 293         return ret;
 294 }
 295
 296 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 297 {
 298         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 299
 300         dev_replace->committed_cursor_left =
 301                 dev_replace->cursor_left_last_write_of_item;
 302 }
 303
 304 int btrfs_dev_replace_start(struct btrfs_root *root,
 305                             struct btrfs_ioctl_dev_replace_args *args)
 306 {
 307         struct btrfs_trans_handle *trans;
 308         struct btrfs_fs_info *fs_info = root->fs_info;
 309         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 310         int ret;
 311         struct btrfs_device *tgt_device = NULL;
 312         struct btrfs_device *src_device = NULL;
 313
 314         if (btrfs_fs_incompat(fs_info, RAID56)) {
 315                 btrfs_warn(fs_info, "dev_replace cannot yet handle RAID5/RAID6");
 316                 return -EINVAL;
 317         }
 318
 319         switch (args->start.cont_reading_from_srcdev_mode) {
 320         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 321         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 322                 break;
 323         default:
 324                 return -EINVAL;
 325         }
 326
 327         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 328             args->start.tgtdev_name[0] == '\0')
 329                 return -EINVAL;
 330
 331         mutex_lock(&fs_info->volume_mutex);
 332         ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
 333                                             &tgt_device);
 334         if (ret) {
 335                 btrfs_err(fs_info, "target device %s is invalid!",
 336                        args->start.tgtdev_name);
 337                 mutex_unlock(&fs_info->volume_mutex);
 338                 return -EINVAL;
 339         }
 340
 341         ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
 342                                             args->start.srcdev_name,
 343                                             &src_device);
 344         mutex_unlock(&fs_info->volume_mutex);
 345         if (ret) {
 346                 ret = -EINVAL;
 347                 goto leave_no_lock;
 348         }
 349
 350         if (tgt_device->total_bytes < src_device->total_bytes) {
 351                 btrfs_err(fs_info, "target device is smaller than source device!");
 352                 ret = -EINVAL;
 353                 goto leave_no_lock;
 354         }
 355
 356         btrfs_dev_replace_lock(dev_replace);
 357         switch (dev_replace->replace_state) {
 358         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 359         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 360         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 361                 break;
 362         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 363         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 364                 args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 365                 goto leave;
 366         }
 367
 368         dev_replace->cont_reading_from_srcdev_mode =
 369                 args->start.cont_reading_from_srcdev_mode;
 370         WARN_ON(!src_device);
 371         dev_replace->srcdev = src_device;
 372         WARN_ON(!tgt_device);
 373         dev_replace->tgtdev = tgt_device;
 374
 375         printk_in_rcu(KERN_INFO
 376                       "BTRFS: dev_replace from %s (devid %llu) to %s started\n",
 377                       src_device->missing ? "<missing disk>" :
 378                         rcu_str_deref(src_device->name),
 379                       src_device->devid,
 380                       rcu_str_deref(tgt_device->name));
 381
 382         tgt_device->total_bytes = src_device->total_bytes;
 383         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
 384         tgt_device->bytes_used = src_device->bytes_used;
 385
 386         /*
 387          * from now on, the writes to the srcdev are all duplicated to
 388          * go to the tgtdev as well (refer to btrfs_map_block()).
 389          */
 390         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 391         dev_replace->time_started = get_seconds();
 392         dev_replace->cursor_left = 0;
 393         dev_replace->committed_cursor_left = 0;
 394         dev_replace->cursor_left_last_write_of_item = 0;
 395         dev_replace->cursor_right = 0;
 396         dev_replace->is_valid = 1;
 397         dev_replace->item_needs_writeback = 1;
 398         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 399         btrfs_dev_replace_unlock(dev_replace);
 400
 401         btrfs_wait_ordered_roots(root->fs_info, -1);
 402
 403         /* force writing the updated state information to disk */
 404         trans = btrfs_start_transaction(root, 0);
 405         if (IS_ERR(trans)) {
 406                 ret = PTR_ERR(trans);
 407                 btrfs_dev_replace_lock(dev_replace);
 408                 goto leave;
 409         }
 410
 411         ret = btrfs_commit_transaction(trans, root);
 412         WARN_ON(ret);
 413
 414         /* the disk copy procedure reuses the scrub code */
 415         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 416                               src_device->total_bytes,
 417                               &dev_replace->scrub_progress, 0, 1);
 418
 419         ret = btrfs_dev_replace_finishing(root->fs_info, ret);
 420         WARN_ON(ret);
 421
 422         return 0;
 423
 424 leave:
 425         dev_replace->srcdev = NULL;
 426         dev_replace->tgtdev = NULL;
 427         btrfs_dev_replace_unlock(dev_replace);
 428 leave_no_lock:
 429         if (tgt_device)
 430                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 431         return ret;
 432 }
 433
 434 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 435                                        int scrub_ret)
 436 {
 437         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 438         struct btrfs_device *tgt_device;
 439         struct btrfs_device *src_device;
 440         struct btrfs_root *root = fs_info->tree_root;
 441         u8 uuid_tmp[BTRFS_UUID_SIZE];
 442         struct btrfs_trans_handle *trans;
 443         int ret = 0;
 444
 445         /* don't allow cancel or unmount to disturb the finishing procedure */
 446         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 447
 448         btrfs_dev_replace_lock(dev_replace);
 449         /* was the operation canceled, or is it finished? */
 450         if (dev_replace->replace_state !=
 451             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 452                 btrfs_dev_replace_unlock(dev_replace);
 453                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 454                 return 0;
 455         }
 456
 457         tgt_device = dev_replace->tgtdev;
 458         src_device = dev_replace->srcdev;
 459         btrfs_dev_replace_unlock(dev_replace);
 460
 461         /* replace old device with new one in mapping tree */
 462         if (!scrub_ret)
 463                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 464                                                                 src_device,
 465                                                                 tgt_device);
 466
 467         /*
 468          * flush all outstanding I/O and inode extent mappings before the
 469          * copy operation is declared as being finished
 470          */
 471         ret = btrfs_start_delalloc_roots(root->fs_info, 0);
 472         if (ret) {
 473                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 474                 return ret;
 475         }
 476         btrfs_wait_ordered_roots(root->fs_info, -1);
 477
 478         trans = btrfs_start_transaction(root, 0);
 479         if (IS_ERR(trans)) {
 480                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 481                 return PTR_ERR(trans);
 482         }
 483         ret = btrfs_commit_transaction(trans, root);
 484         WARN_ON(ret);
 485
 486         /* keep away write_all_supers() during the finishing procedure */
 487         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
 488         btrfs_dev_replace_lock(dev_replace);
 489         dev_replace->replace_state =
 490                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 491                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 492         dev_replace->tgtdev = NULL;
 493         dev_replace->srcdev = NULL;
 494         dev_replace->time_stopped = get_seconds();
 495         dev_replace->item_needs_writeback = 1;
 496
 497         if (scrub_ret) {
 498                 printk_in_rcu(KERN_ERR
 499                               "BTRFS: btrfs_scrub_dev(%s, %llu, %s) failed %d\n",
 500                               src_device->missing ? "<missing disk>" :
 501                                 rcu_str_deref(src_device->name),
 502                               src_device->devid,
 503                               rcu_str_deref(tgt_device->name), scrub_ret);
 504                 btrfs_dev_replace_unlock(dev_replace);
 505                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 506                 if (tgt_device)
 507                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 508                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 509
 510                 return 0;
 511         }
 512
 513         printk_in_rcu(KERN_INFO
 514                       "BTRFS: dev_replace from %s (devid %llu) to %s) finished\n",
 515                       src_device->missing ? "<missing disk>" :
 516                         rcu_str_deref(src_device->name),
 517                       src_device->devid,
 518                       rcu_str_deref(tgt_device->name));
 519         tgt_device->is_tgtdev_for_dev_replace = 0;
 520         tgt_device->devid = src_device->devid;
 521         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 522         tgt_device->bytes_used = src_device->bytes_used;
 523         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 524         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 525         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 526         tgt_device->total_bytes = src_device->total_bytes;
 527         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
 528         tgt_device->bytes_used = src_device->bytes_used;
 529         if (fs_info->sb->s_bdev == src_device->bdev)
 530                 fs_info->sb->s_bdev = tgt_device->bdev;
 531         if (fs_info->fs_devices->latest_bdev == src_device->bdev)
 532                 fs_info->fs_devices->latest_bdev = tgt_device->bdev;
 533         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 534
 535         btrfs_rm_dev_replace_srcdev(fs_info, src_device);
 536
 537         /*
 538          * this is again a consistent state where no dev_replace procedure
 539          * is running, the target device is part of the filesystem, the
 540          * source device is not part of the filesystem anymore and its 1st
 541          * superblock is scratched out so that it is no longer marked to
 542          * belong to this filesystem.
 543          */
 544         btrfs_dev_replace_unlock(dev_replace);
 545         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 546
 547         /* write back the superblocks */
 548         trans = btrfs_start_transaction(root, 0);
 549         if (!IS_ERR(trans))
 550                 btrfs_commit_transaction(trans, root);
 551
 552         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 553
 554         return 0;
 555 }
 556
 557 static void btrfs_dev_replace_update_device_in_mapping_tree(
 558                                                 struct btrfs_fs_info *fs_info,
 559                                                 struct btrfs_device *srcdev,
 560                                                 struct btrfs_device *tgtdev)
 561 {
 562         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 563         struct extent_map *em;
 564         struct map_lookup *map;
 565         u64 start = 0;
 566         int i;
 567
 568         write_lock(&em_tree->lock);
 569         do {
 570                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 571                 if (!em)
 572                         break;
 573                 map = (struct map_lookup *)em->bdev;
 574                 for (i = 0; i < map->num_stripes; i++)
 575                         if (srcdev == map->stripes[i].dev)
 576                                 map->stripes[i].dev = tgtdev;
 577                 start = em->start + em->len;
 578                 free_extent_map(em);
 579         } while (start);
 580         write_unlock(&em_tree->lock);
 581 }
 582
 583 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
 584                                          char *srcdev_name,
 585                                          struct btrfs_device **device)
 586 {
 587         int ret;
 588
 589         if (srcdevid) {
 590                 ret = 0;
 591                 *device = btrfs_find_device(root->fs_info, srcdevid, NULL,
 592                                             NULL);
 593                 if (!*device)
 594                         ret = -ENOENT;
 595         } else {
 596                 ret = btrfs_find_device_missing_or_by_path(root, srcdev_name,
 597                                                            device);
 598         }
 599         return ret;
 600 }
 601
 602 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 603                               struct btrfs_ioctl_dev_replace_args *args)
 604 {
 605         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 606
 607         btrfs_dev_replace_lock(dev_replace);
 608         /* even if !dev_replace_is_valid, the values are good enough for
 609          * the replace_status ioctl */
 610         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 611         args->status.replace_state = dev_replace->replace_state;
 612         args->status.time_started = dev_replace->time_started;
 613         args->status.time_stopped = dev_replace->time_stopped;
 614         args->status.num_write_errors =
 615                 atomic64_read(&dev_replace->num_write_errors);
 616         args->status.num_uncorrectable_read_errors =
 617                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 618         switch (dev_replace->replace_state) {
 619         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 620         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 621                 args->status.progress_1000 = 0;
 622                 break;
 623         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 624                 args->status.progress_1000 = 1000;
 625                 break;
 626         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 627         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 628                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
 629                         div64_u64(dev_replace->srcdev->total_bytes, 1000));
 630                 break;
 631         }
 632         btrfs_dev_replace_unlock(dev_replace);
 633 }
 634
 635 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 636                              struct btrfs_ioctl_dev_replace_args *args)
 637 {
 638         args->result = __btrfs_dev_replace_cancel(fs_info);
 639         return 0;
 640 }
 641
 642 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 643 {
 644         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 645         struct btrfs_device *tgt_device = NULL;
 646         struct btrfs_trans_handle *trans;
 647         struct btrfs_root *root = fs_info->tree_root;
 648         u64 result;
 649         int ret;
 650
 651         if (fs_info->sb->s_flags & MS_RDONLY)
 652                 return -EROFS;
 653
 654         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 655         btrfs_dev_replace_lock(dev_replace);
 656         switch (dev_replace->replace_state) {
 657         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 658         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 659         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 660                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 661                 btrfs_dev_replace_unlock(dev_replace);
 662                 goto leave;
 663         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 664         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 665                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 666                 tgt_device = dev_replace->tgtdev;
 667                 dev_replace->tgtdev = NULL;
 668                 dev_replace->srcdev = NULL;
 669                 break;
 670         }
 671         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 672         dev_replace->time_stopped = get_seconds();
 673         dev_replace->item_needs_writeback = 1;
 674         btrfs_dev_replace_unlock(dev_replace);
 675         btrfs_scrub_cancel(fs_info);
 676
 677         trans = btrfs_start_transaction(root, 0);
 678         if (IS_ERR(trans)) {
 679                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 680                 return PTR_ERR(trans);
 681         }
 682         ret = btrfs_commit_transaction(trans, root);
 683         WARN_ON(ret);
 684         if (tgt_device)
 685                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 686
 687 leave:
 688         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 689         return result;
 690 }
 691
 692 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 693 {
 694         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 695
 696         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 697         btrfs_dev_replace_lock(dev_replace);
 698         switch (dev_replace->replace_state) {
 699         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 700         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 701         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 702         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 703                 break;
 704         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 705                 dev_replace->replace_state =
 706                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 707                 dev_replace->time_stopped = get_seconds();
 708                 dev_replace->item_needs_writeback = 1;
 709                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 710                 break;
 711         }
 712
 713         btrfs_dev_replace_unlock(dev_replace);
 714         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 715 }
 716
 717 /* resume dev_replace procedure that was interrupted by unmount */
 718 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 719 {
 720         struct task_struct *task;
 721         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 722
 723         btrfs_dev_replace_lock(dev_replace);
 724         switch (dev_replace->replace_state) {
 725         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 726         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 727         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 728                 btrfs_dev_replace_unlock(dev_replace);
 729                 return 0;
 730         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 731                 break;
 732         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 733                 dev_replace->replace_state =
 734                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 735                 break;
 736         }
 737         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 738                 btrfs_info(fs_info, "cannot continue dev_replace, tgtdev is missing");
 739                 btrfs_info(fs_info,
 740                         "you may cancel the operation after 'mount -o degraded'");
 741                 btrfs_dev_replace_unlock(dev_replace);
 742                 return 0;
 743         }
 744         btrfs_dev_replace_unlock(dev_replace);
 745
 746         WARN_ON(atomic_xchg(
 747                 &fs_info->mutually_exclusive_operation_running, 1));
 748         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 749         return PTR_ERR_OR_ZERO(task);
 750 }
 751
 752 static int btrfs_dev_replace_kthread(void *data)
 753 {
 754         struct btrfs_fs_info *fs_info = data;
 755         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 756         struct btrfs_ioctl_dev_replace_args *status_args;
 757         u64 progress;
 758
 759         status_args = kzalloc(sizeof(*status_args), GFP_NOFS);
 760         if (status_args) {
 761                 btrfs_dev_replace_status(fs_info, status_args);
 762                 progress = status_args->status.progress_1000;
 763                 kfree(status_args);
 764                 do_div(progress, 10);
 765                 printk_in_rcu(KERN_INFO
 766                         "BTRFS: continuing dev_replace from %s (devid %llu) to %s @%u%%\n",
 767                         dev_replace->srcdev->missing ? "<missing disk>" :
 768                         rcu_str_deref(dev_replace->srcdev->name),
 769                         dev_replace->srcdev->devid,
 770                         dev_replace->tgtdev ?
 771                         rcu_str_deref(dev_replace->tgtdev->name) :
 772                         "<missing target disk>",
 773                         (unsigned int)progress);
 774         }
 775         btrfs_dev_replace_continue_on_mount(fs_info);
 776         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
 777
 778         return 0;
 779 }
 780
 781 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 782 {
 783         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 784         int ret;
 785
 786         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 787                               dev_replace->committed_cursor_left,
 788                               dev_replace->srcdev->total_bytes,
 789                               &dev_replace->scrub_progress, 0, 1);
 790         ret = btrfs_dev_replace_finishing(fs_info, ret);
 791         WARN_ON(ret);
 792         return 0;
 793 }
 794
 795 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 796 {
 797         if (!dev_replace->is_valid)
 798                 return 0;
 799
 800         switch (dev_replace->replace_state) {
 801         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 802         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 803         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 804                 return 0;
 805         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 806         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 807                 /*
 808                  * return true even if tgtdev is missing (this is
 809                  * something that can happen if the dev_replace
 810                  * procedure is suspended by an umount and then
 811                  * the tgtdev is missing (or "btrfs dev scan") was
 812                  * not called and the the filesystem is remounted
 813                  * in degraded state. This does not stop the
 814                  * dev_replace procedure. It needs to be canceled
 815                  * manually if the cancelation is wanted.
 816                  */
 817                 break;
 818         }
 819         return 1;
 820 }
 821
 822 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
 823 {
 824         /* the beginning is just an optimization for the typical case */
 825         if (atomic_read(&dev_replace->nesting_level) == 0) {
 826 acquire_lock:
 827                 /* this is not a nested case where the same thread
 828                  * is trying to acqurire the same lock twice */
 829                 mutex_lock(&dev_replace->lock);
 830                 mutex_lock(&dev_replace->lock_management_lock);
 831                 dev_replace->lock_owner = current->pid;
 832                 atomic_inc(&dev_replace->nesting_level);
 833                 mutex_unlock(&dev_replace->lock_management_lock);
 834                 return;
 835         }
 836
 837         mutex_lock(&dev_replace->lock_management_lock);
 838         if (atomic_read(&dev_replace->nesting_level) > 0 &&
 839             dev_replace->lock_owner == current->pid) {
 840                 WARN_ON(!mutex_is_locked(&dev_replace->lock));
 841                 atomic_inc(&dev_replace->nesting_level);
 842                 mutex_unlock(&dev_replace->lock_management_lock);
 843                 return;
 844         }
 845
 846         mutex_unlock(&dev_replace->lock_management_lock);
 847         goto acquire_lock;
 848 }
 849
 850 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
 851 {
 852         WARN_ON(!mutex_is_locked(&dev_replace->lock));
 853         mutex_lock(&dev_replace->lock_management_lock);
 854         WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
 855         WARN_ON(dev_replace->lock_owner != current->pid);
 856         atomic_dec(&dev_replace->nesting_level);
 857         if (atomic_read(&dev_replace->nesting_level) == 0) {
 858                 dev_replace->lock_owner = 0;
 859                 mutex_unlock(&dev_replace->lock_management_lock);
 860                 mutex_unlock(&dev_replace->lock);
 861         } else {
 862                 mutex_unlock(&dev_replace->lock_management_lock);
 863         }
 864 }