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 int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
  48                                          char *srcdev_name,
  49                                          struct btrfs_device **device);
  50 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info);
  51 static int btrfs_dev_replace_kthread(void *data);
  52 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
  53
  54
  55 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  56 {
  57         struct btrfs_key key;
  58         struct btrfs_root *dev_root = fs_info->dev_root;
  59         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  60         struct extent_buffer *eb;
  61         int slot;
  62         int ret = 0;
  63         struct btrfs_path *path = NULL;
  64         int item_size;
  65         struct btrfs_dev_replace_item *ptr;
  66         u64 src_devid;
  67
  68         path = btrfs_alloc_path();
  69         if (!path) {
  70                 ret = -ENOMEM;
  71                 goto out;
  72         }
  73
  74         key.objectid = 0;
  75         key.type = BTRFS_DEV_REPLACE_KEY;
  76         key.offset = 0;
  77         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  78         if (ret) {
  79 no_valid_dev_replace_entry_found:
  80                 ret = 0;
  81                 dev_replace->replace_state =
  82                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
  83                 dev_replace->cont_reading_from_srcdev_mode =
  84                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
  85                 dev_replace->replace_state = 0;
  86                 dev_replace->time_started = 0;
  87                 dev_replace->time_stopped = 0;
  88                 atomic64_set(&dev_replace->num_write_errors, 0);
  89                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
  90                 dev_replace->cursor_left = 0;
  91                 dev_replace->committed_cursor_left = 0;
  92                 dev_replace->cursor_left_last_write_of_item = 0;
  93                 dev_replace->cursor_right = 0;
  94                 dev_replace->srcdev = NULL;
  95                 dev_replace->tgtdev = NULL;
  96                 dev_replace->is_valid = 0;
  97                 dev_replace->item_needs_writeback = 0;
  98                 goto out;
  99         }
 100         slot = path->slots[0];
 101         eb = path->nodes[0];
 102         item_size = btrfs_item_size_nr(eb, slot);
 103         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
 104
 105         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
 106                 btrfs_warn(fs_info,
 107                         "dev_replace entry found has unexpected size, ignore entry");
 108                 goto no_valid_dev_replace_entry_found;
 109         }
 110
 111         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
 112         dev_replace->cont_reading_from_srcdev_mode =
 113                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
 114         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
 115         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
 116         dev_replace->time_stopped =
 117                 btrfs_dev_replace_time_stopped(eb, ptr);
 118         atomic64_set(&dev_replace->num_write_errors,
 119                      btrfs_dev_replace_num_write_errors(eb, ptr));
 120         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 121                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 122         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 123         dev_replace->committed_cursor_left = dev_replace->cursor_left;
 124         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 125         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 126         dev_replace->is_valid = 1;
 127
 128         dev_replace->item_needs_writeback = 0;
 129         switch (dev_replace->replace_state) {
 130         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 131         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 132         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 133                 dev_replace->srcdev = NULL;
 134                 dev_replace->tgtdev = NULL;
 135                 break;
 136         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 137         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 138                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
 139                                                         NULL, NULL);
 140                 dev_replace->tgtdev = btrfs_find_device(fs_info,
 141                                                         BTRFS_DEV_REPLACE_DEVID,
 142                                                         NULL, NULL);
 143                 /*
 144                  * allow 'btrfs dev replace_cancel' if src/tgt device is
 145                  * missing
 146                  */
 147                 if (!dev_replace->srcdev &&
 148                     !btrfs_test_opt(dev_root, DEGRADED)) {
 149                         ret = -EIO;
 150                         btrfs_warn(fs_info,
 151                            "cannot mount because device replace operation is ongoing and");
 152                         btrfs_warn(fs_info,
 153                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 154                            src_devid);
 155                 }
 156                 if (!dev_replace->tgtdev &&
 157                     !btrfs_test_opt(dev_root, DEGRADED)) {
 158                         ret = -EIO;
 159                         btrfs_warn(fs_info,
 160                            "cannot mount because device replace operation is ongoing and");
 161                         btrfs_warn(fs_info,
 162                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 163                                 BTRFS_DEV_REPLACE_DEVID);
 164                 }
 165                 if (dev_replace->tgtdev) {
 166                         if (dev_replace->srcdev) {
 167                                 dev_replace->tgtdev->total_bytes =
 168                                         dev_replace->srcdev->total_bytes;
 169                                 dev_replace->tgtdev->disk_total_bytes =
 170                                         dev_replace->srcdev->disk_total_bytes;
 171                                 dev_replace->tgtdev->bytes_used =
 172                                         dev_replace->srcdev->bytes_used;
 173                         }
 174                         dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
 175                         btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
 176                                 dev_replace->tgtdev);
 177                 }
 178                 break;
 179         }
 180
 181 out:
 182         if (path)
 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);
 203         if (!dev_replace->is_valid ||
 204             !dev_replace->item_needs_writeback) {
 205                 btrfs_dev_replace_unlock(dev_replace);
 206                 return 0;
 207         }
 208         btrfs_dev_replace_unlock(dev_replace);
 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, "error %d while searching for dev_replace item!",
 222                         ret);
 223                 goto out;
 224         }
 225
 226         if (ret == 0 &&
 227             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 228                 /*
 229                  * need to delete old one and insert a new one.
 230                  * Since no attempt is made to recover any old state, if the
 231                  * dev_replace state is 'running', the data on the target
 232                  * drive is lost.
 233                  * It would be possible to recover the state: just make sure
 234                  * that the beginning of the item is never changed and always
 235                  * contains all the essential information. Then read this
 236                  * minimal set of information and use it as a base for the
 237                  * new state.
 238                  */
 239                 ret = btrfs_del_item(trans, dev_root, path);
 240                 if (ret != 0) {
 241                         btrfs_warn(fs_info, "delete too small dev_replace item failed %d!",
 242                                 ret);
 243                         goto out;
 244                 }
 245                 ret = 1;
 246         }
 247
 248         if (ret == 1) {
 249                 /* need to insert a new item */
 250                 btrfs_release_path(path);
 251                 ret = btrfs_insert_empty_item(trans, dev_root, path,
 252                                               &key, sizeof(*ptr));
 253                 if (ret < 0) {
 254                         btrfs_warn(fs_info, "insert dev_replace item failed %d!",
 255                                 ret);
 256                         goto out;
 257                 }
 258         }
 259
 260         eb = path->nodes[0];
 261         ptr = btrfs_item_ptr(eb, path->slots[0],
 262                              struct btrfs_dev_replace_item);
 263
 264         btrfs_dev_replace_lock(dev_replace);
 265         if (dev_replace->srcdev)
 266                 btrfs_set_dev_replace_src_devid(eb, ptr,
 267                         dev_replace->srcdev->devid);
 268         else
 269                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 270         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 271                 dev_replace->cont_reading_from_srcdev_mode);
 272         btrfs_set_dev_replace_replace_state(eb, ptr,
 273                 dev_replace->replace_state);
 274         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 275         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 276         btrfs_set_dev_replace_num_write_errors(eb, ptr,
 277                 atomic64_read(&dev_replace->num_write_errors));
 278         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 279                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 280         dev_replace->cursor_left_last_write_of_item =
 281                 dev_replace->cursor_left;
 282         btrfs_set_dev_replace_cursor_left(eb, ptr,
 283                 dev_replace->cursor_left_last_write_of_item);
 284         btrfs_set_dev_replace_cursor_right(eb, ptr,
 285                 dev_replace->cursor_right);
 286         dev_replace->item_needs_writeback = 0;
 287         btrfs_dev_replace_unlock(dev_replace);
 288
 289         btrfs_mark_buffer_dirty(eb);
 290
 291 out:
 292         btrfs_free_path(path);
 293
 294         return ret;
 295 }
 296
 297 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 298 {
 299         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 300
 301         dev_replace->committed_cursor_left =
 302                 dev_replace->cursor_left_last_write_of_item;
 303 }
 304
 305 int btrfs_dev_replace_start(struct btrfs_root *root,
 306                             struct btrfs_ioctl_dev_replace_args *args)
 307 {
 308         struct btrfs_trans_handle *trans;
 309         struct btrfs_fs_info *fs_info = root->fs_info;
 310         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 311         int ret;
 312         struct btrfs_device *tgt_device = NULL;
 313         struct btrfs_device *src_device = NULL;
 314
 315         if (btrfs_fs_incompat(fs_info, RAID56)) {
 316                 btrfs_warn(fs_info, "dev_replace cannot yet handle RAID5/RAID6");
 317                 return -EOPNOTSUPP;
 318         }
 319
 320         switch (args->start.cont_reading_from_srcdev_mode) {
 321         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 322         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 323                 break;
 324         default:
 325                 return -EINVAL;
 326         }
 327
 328         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
 329             args->start.tgtdev_name[0] == '\0')
 330                 return -EINVAL;
 331
 332         mutex_lock(&fs_info->volume_mutex);
 333         ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
 334                                             &tgt_device);
 335         if (ret) {
 336                 btrfs_err(fs_info, "target device %s is invalid!",
 337                        args->start.tgtdev_name);
 338                 mutex_unlock(&fs_info->volume_mutex);
 339                 return -EINVAL;
 340         }
 341
 342         ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
 343                                             args->start.srcdev_name,
 344                                             &src_device);
 345         mutex_unlock(&fs_info->volume_mutex);
 346         if (ret) {
 347                 ret = -EINVAL;
 348                 goto leave_no_lock;
 349         }
 350
 351         if (tgt_device->total_bytes < src_device->total_bytes) {
 352                 btrfs_err(fs_info, "target device is smaller than source device!");
 353                 ret = -EINVAL;
 354                 goto leave_no_lock;
 355         }
 356
 357         btrfs_dev_replace_lock(dev_replace);
 358         switch (dev_replace->replace_state) {
 359         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 360         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 361         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 362                 break;
 363         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 364         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 365                 args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 366                 goto leave;
 367         }
 368
 369         dev_replace->cont_reading_from_srcdev_mode =
 370                 args->start.cont_reading_from_srcdev_mode;
 371         WARN_ON(!src_device);
 372         dev_replace->srcdev = src_device;
 373         WARN_ON(!tgt_device);
 374         dev_replace->tgtdev = tgt_device;
 375
 376         printk_in_rcu(KERN_INFO
 377                       "BTRFS: dev_replace from %s (devid %llu) to %s started\n",
 378                       src_device->missing ? "<missing disk>" :
 379                         rcu_str_deref(src_device->name),
 380                       src_device->devid,
 381                       rcu_str_deref(tgt_device->name));
 382
 383         tgt_device->total_bytes = src_device->total_bytes;
 384         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
 385         tgt_device->bytes_used = src_device->bytes_used;
 386
 387         /*
 388          * from now on, the writes to the srcdev are all duplicated to
 389          * go to the tgtdev as well (refer to btrfs_map_block()).
 390          */
 391         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 392         dev_replace->time_started = get_seconds();
 393         dev_replace->cursor_left = 0;
 394         dev_replace->committed_cursor_left = 0;
 395         dev_replace->cursor_left_last_write_of_item = 0;
 396         dev_replace->cursor_right = 0;
 397         dev_replace->is_valid = 1;
 398         dev_replace->item_needs_writeback = 1;
 399         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 400         btrfs_dev_replace_unlock(dev_replace);
 401
 402         btrfs_wait_ordered_roots(root->fs_info, -1);
 403
 404         /* force writing the updated state information to disk */
 405         trans = btrfs_start_transaction(root, 0);
 406         if (IS_ERR(trans)) {
 407                 ret = PTR_ERR(trans);
 408                 btrfs_dev_replace_lock(dev_replace);
 409                 goto leave;
 410         }
 411
 412         ret = btrfs_commit_transaction(trans, root);
 413         WARN_ON(ret);
 414
 415         /* the disk copy procedure reuses the scrub code */
 416         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 417                               src_device->total_bytes,
 418                               &dev_replace->scrub_progress, 0, 1);
 419
 420         ret = btrfs_dev_replace_finishing(root->fs_info, ret);
 421         WARN_ON(ret);
 422
 423         return 0;
 424
 425 leave:
 426         dev_replace->srcdev = NULL;
 427         dev_replace->tgtdev = NULL;
 428         btrfs_dev_replace_unlock(dev_replace);
 429 leave_no_lock:
 430         if (tgt_device)
 431                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 432         return ret;
 433 }
 434
 435 /*
 436  * blocked until all flighting bios are finished.
 437  */
 438 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 439 {
 440         s64 writers;
 441         DEFINE_WAIT(wait);
 442
 443         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 444         do {
 445                 prepare_to_wait(&fs_info->replace_wait, &wait,
 446                                 TASK_UNINTERRUPTIBLE);
 447                 writers = percpu_counter_sum(&fs_info->bio_counter);
 448                 if (writers)
 449                         schedule();
 450                 finish_wait(&fs_info->replace_wait, &wait);
 451         } while (writers);
 452 }
 453
 454 /*
 455  * we have removed target device, it is safe to allow new bios request.
 456  */
 457 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 458 {
 459         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 460         if (waitqueue_active(&fs_info->replace_wait))
 461                 wake_up(&fs_info->replace_wait);
 462 }
 463
 464 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 465                                        int scrub_ret)
 466 {
 467         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 468         struct btrfs_device *tgt_device;
 469         struct btrfs_device *src_device;
 470         struct btrfs_root *root = fs_info->tree_root;
 471         u8 uuid_tmp[BTRFS_UUID_SIZE];
 472         struct btrfs_trans_handle *trans;
 473         int ret = 0;
 474
 475         /* don't allow cancel or unmount to disturb the finishing procedure */
 476         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 477
 478         btrfs_dev_replace_lock(dev_replace);
 479         /* was the operation canceled, or is it finished? */
 480         if (dev_replace->replace_state !=
 481             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 482                 btrfs_dev_replace_unlock(dev_replace);
 483                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 484                 return 0;
 485         }
 486
 487         tgt_device = dev_replace->tgtdev;
 488         src_device = dev_replace->srcdev;
 489         btrfs_dev_replace_unlock(dev_replace);
 490
 491         /*
 492          * flush all outstanding I/O and inode extent mappings before the
 493          * copy operation is declared as being finished
 494          */
 495         ret = btrfs_start_delalloc_roots(root->fs_info, 0, -1);
 496         if (ret) {
 497                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 498                 return ret;
 499         }
 500         btrfs_wait_ordered_roots(root->fs_info, -1);
 501
 502         trans = btrfs_start_transaction(root, 0);
 503         if (IS_ERR(trans)) {
 504                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 505                 return PTR_ERR(trans);
 506         }
 507         ret = btrfs_commit_transaction(trans, root);
 508         WARN_ON(ret);
 509
 510         /* keep away write_all_supers() during the finishing procedure */
 511         mutex_lock(&root->fs_info->chunk_mutex);
 512         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
 513         btrfs_dev_replace_lock(dev_replace);
 514         dev_replace->replace_state =
 515                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 516                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 517         dev_replace->tgtdev = NULL;
 518         dev_replace->srcdev = NULL;
 519         dev_replace->time_stopped = get_seconds();
 520         dev_replace->item_needs_writeback = 1;
 521
 522         /* replace old device with new one in mapping tree */
 523         if (!scrub_ret) {
 524                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 525                                                                 src_device,
 526                                                                 tgt_device);
 527         } else {
 528                 printk_in_rcu(KERN_ERR
 529                               "BTRFS: btrfs_scrub_dev(%s, %llu, %s) failed %d\n",
 530                               src_device->missing ? "<missing disk>" :
 531                                 rcu_str_deref(src_device->name),
 532                               src_device->devid,
 533                               rcu_str_deref(tgt_device->name), scrub_ret);
 534                 btrfs_dev_replace_unlock(dev_replace);
 535                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 536                 mutex_unlock(&root->fs_info->chunk_mutex);
 537                 if (tgt_device)
 538                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 539                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 540
 541                 return 0;
 542         }
 543
 544         printk_in_rcu(KERN_INFO
 545                       "BTRFS: dev_replace from %s (devid %llu) to %s) finished\n",
 546                       src_device->missing ? "<missing disk>" :
 547                         rcu_str_deref(src_device->name),
 548                       src_device->devid,
 549                       rcu_str_deref(tgt_device->name));
 550         tgt_device->is_tgtdev_for_dev_replace = 0;
 551         tgt_device->devid = src_device->devid;
 552         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 553         tgt_device->bytes_used = src_device->bytes_used;
 554         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 555         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 556         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 557         tgt_device->total_bytes = src_device->total_bytes;
 558         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
 559         tgt_device->bytes_used = src_device->bytes_used;
 560         if (fs_info->sb->s_bdev == src_device->bdev)
 561                 fs_info->sb->s_bdev = tgt_device->bdev;
 562         if (fs_info->fs_devices->latest_bdev == src_device->bdev)
 563                 fs_info->fs_devices->latest_bdev = tgt_device->bdev;
 564         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 565
 566         /* replace the sysfs entry */
 567         btrfs_kobj_rm_device(fs_info, src_device);
 568         btrfs_kobj_add_device(fs_info, tgt_device);
 569
 570         btrfs_rm_dev_replace_blocked(fs_info);
 571
 572         btrfs_rm_dev_replace_srcdev(fs_info, src_device);
 573
 574         btrfs_rm_dev_replace_unblocked(fs_info);
 575
 576         /*
 577          * this is again a consistent state where no dev_replace procedure
 578          * is running, the target device is part of the filesystem, the
 579          * source device is not part of the filesystem anymore and its 1st
 580          * superblock is scratched out so that it is no longer marked to
 581          * belong to this filesystem.
 582          */
 583         btrfs_dev_replace_unlock(dev_replace);
 584         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 585         mutex_unlock(&root->fs_info->chunk_mutex);
 586
 587         /* write back the superblocks */
 588         trans = btrfs_start_transaction(root, 0);
 589         if (!IS_ERR(trans))
 590                 btrfs_commit_transaction(trans, root);
 591
 592         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 593
 594         return 0;
 595 }
 596
 597 static void btrfs_dev_replace_update_device_in_mapping_tree(
 598                                                 struct btrfs_fs_info *fs_info,
 599                                                 struct btrfs_device *srcdev,
 600                                                 struct btrfs_device *tgtdev)
 601 {
 602         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 603         struct extent_map *em;
 604         struct map_lookup *map;
 605         u64 start = 0;
 606         int i;
 607
 608         write_lock(&em_tree->lock);
 609         do {
 610                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 611                 if (!em)
 612                         break;
 613                 map = (struct map_lookup *)em->bdev;
 614                 for (i = 0; i < map->num_stripes; i++)
 615                         if (srcdev == map->stripes[i].dev)
 616                                 map->stripes[i].dev = tgtdev;
 617                 start = em->start + em->len;
 618                 free_extent_map(em);
 619         } while (start);
 620         write_unlock(&em_tree->lock);
 621 }
 622
 623 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
 624                                          char *srcdev_name,
 625                                          struct btrfs_device **device)
 626 {
 627         int ret;
 628
 629         if (srcdevid) {
 630                 ret = 0;
 631                 *device = btrfs_find_device(root->fs_info, srcdevid, NULL,
 632                                             NULL);
 633                 if (!*device)
 634                         ret = -ENOENT;
 635         } else {
 636                 ret = btrfs_find_device_missing_or_by_path(root, srcdev_name,
 637                                                            device);
 638         }
 639         return ret;
 640 }
 641
 642 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 643                               struct btrfs_ioctl_dev_replace_args *args)
 644 {
 645         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 646
 647         btrfs_dev_replace_lock(dev_replace);
 648         /* even if !dev_replace_is_valid, the values are good enough for
 649          * the replace_status ioctl */
 650         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 651         args->status.replace_state = dev_replace->replace_state;
 652         args->status.time_started = dev_replace->time_started;
 653         args->status.time_stopped = dev_replace->time_stopped;
 654         args->status.num_write_errors =
 655                 atomic64_read(&dev_replace->num_write_errors);
 656         args->status.num_uncorrectable_read_errors =
 657                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 658         switch (dev_replace->replace_state) {
 659         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 660         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 661                 args->status.progress_1000 = 0;
 662                 break;
 663         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 664                 args->status.progress_1000 = 1000;
 665                 break;
 666         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 667         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 668                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
 669                         div64_u64(dev_replace->srcdev->total_bytes, 1000));
 670                 break;
 671         }
 672         btrfs_dev_replace_unlock(dev_replace);
 673 }
 674
 675 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 676                              struct btrfs_ioctl_dev_replace_args *args)
 677 {
 678         args->result = __btrfs_dev_replace_cancel(fs_info);
 679         return 0;
 680 }
 681
 682 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 683 {
 684         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 685         struct btrfs_device *tgt_device = NULL;
 686         struct btrfs_trans_handle *trans;
 687         struct btrfs_root *root = fs_info->tree_root;
 688         u64 result;
 689         int ret;
 690
 691         if (fs_info->sb->s_flags & MS_RDONLY)
 692                 return -EROFS;
 693
 694         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 695         btrfs_dev_replace_lock(dev_replace);
 696         switch (dev_replace->replace_state) {
 697         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 698         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 699         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 700                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 701                 btrfs_dev_replace_unlock(dev_replace);
 702                 goto leave;
 703         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 704         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 705                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 706                 tgt_device = dev_replace->tgtdev;
 707                 dev_replace->tgtdev = NULL;
 708                 dev_replace->srcdev = NULL;
 709                 break;
 710         }
 711         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 712         dev_replace->time_stopped = get_seconds();
 713         dev_replace->item_needs_writeback = 1;
 714         btrfs_dev_replace_unlock(dev_replace);
 715         btrfs_scrub_cancel(fs_info);
 716
 717         trans = btrfs_start_transaction(root, 0);
 718         if (IS_ERR(trans)) {
 719                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 720                 return PTR_ERR(trans);
 721         }
 722         ret = btrfs_commit_transaction(trans, root);
 723         WARN_ON(ret);
 724         if (tgt_device)
 725                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 726
 727 leave:
 728         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 729         return result;
 730 }
 731
 732 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 733 {
 734         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 735
 736         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 737         btrfs_dev_replace_lock(dev_replace);
 738         switch (dev_replace->replace_state) {
 739         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 740         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 741         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 742         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 743                 break;
 744         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 745                 dev_replace->replace_state =
 746                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 747                 dev_replace->time_stopped = get_seconds();
 748                 dev_replace->item_needs_writeback = 1;
 749                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 750                 break;
 751         }
 752
 753         btrfs_dev_replace_unlock(dev_replace);
 754         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 755 }
 756
 757 /* resume dev_replace procedure that was interrupted by unmount */
 758 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 759 {
 760         struct task_struct *task;
 761         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 762
 763         btrfs_dev_replace_lock(dev_replace);
 764         switch (dev_replace->replace_state) {
 765         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 766         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 767         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 768                 btrfs_dev_replace_unlock(dev_replace);
 769                 return 0;
 770         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 771                 break;
 772         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 773                 dev_replace->replace_state =
 774                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 775                 break;
 776         }
 777         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 778                 btrfs_info(fs_info, "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);
 782                 return 0;
 783         }
 784         btrfs_dev_replace_unlock(dev_replace);
 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_NOFS);
 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                 do_div(progress, 10);
 805                 printk_in_rcu(KERN_INFO
 806                         "BTRFS: continuing dev_replace from %s (devid %llu) to %s @%u%%\n",
 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                               dev_replace->srcdev->total_bytes,
 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 cancelation is wanted.
 856                  */
 857                 break;
 858         }
 859         return 1;
 860 }
 861
 862 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
 863 {
 864         /* the beginning is just an optimization for the typical case */
 865         if (atomic_read(&dev_replace->nesting_level) == 0) {
 866 acquire_lock:
 867                 /* this is not a nested case where the same thread
 868                  * is trying to acqurire the same lock twice */
 869                 mutex_lock(&dev_replace->lock);
 870                 mutex_lock(&dev_replace->lock_management_lock);
 871                 dev_replace->lock_owner = current->pid;
 872                 atomic_inc(&dev_replace->nesting_level);
 873                 mutex_unlock(&dev_replace->lock_management_lock);
 874                 return;
 875         }
 876
 877         mutex_lock(&dev_replace->lock_management_lock);
 878         if (atomic_read(&dev_replace->nesting_level) > 0 &&
 879             dev_replace->lock_owner == current->pid) {
 880                 WARN_ON(!mutex_is_locked(&dev_replace->lock));
 881                 atomic_inc(&dev_replace->nesting_level);
 882                 mutex_unlock(&dev_replace->lock_management_lock);
 883                 return;
 884         }
 885
 886         mutex_unlock(&dev_replace->lock_management_lock);
 887         goto acquire_lock;
 888 }
 889
 890 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
 891 {
 892         WARN_ON(!mutex_is_locked(&dev_replace->lock));
 893         mutex_lock(&dev_replace->lock_management_lock);
 894         WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
 895         WARN_ON(dev_replace->lock_owner != current->pid);
 896         atomic_dec(&dev_replace->nesting_level);
 897         if (atomic_read(&dev_replace->nesting_level) == 0) {
 898                 dev_replace->lock_owner = 0;
 899                 mutex_unlock(&dev_replace->lock_management_lock);
 900                 mutex_unlock(&dev_replace->lock);
 901         } else {
 902                 mutex_unlock(&dev_replace->lock_management_lock);
 903         }
 904 }
 905
 906 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
 907 {
 908         percpu_counter_inc(&fs_info->bio_counter);
 909 }
 910
 911 void btrfs_bio_counter_dec(struct btrfs_fs_info *fs_info)
 912 {
 913         percpu_counter_dec(&fs_info->bio_counter);
 914
 915         if (waitqueue_active(&fs_info->replace_wait))
 916                 wake_up(&fs_info->replace_wait);
 917 }
 918
 919 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
 920 {
 921         DEFINE_WAIT(wait);
 922 again:
 923         percpu_counter_inc(&fs_info->bio_counter);
 924         if (test_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state)) {
 925                 btrfs_bio_counter_dec(fs_info);
 926                 wait_event(fs_info->replace_wait,
 927                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 928                                      &fs_info->fs_state));
 929                 goto again;
 930         }
 931
 932 }