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         if (src_device->fs_devices->seeding)
 566                 fs_info->fs_devices->rw_devices++;
 567
 568         /* replace the sysfs entry */
 569         btrfs_kobj_rm_device(fs_info, src_device);
 570         btrfs_kobj_add_device(fs_info, tgt_device);
 571
 572         btrfs_dev_replace_unlock(dev_replace);
 573
 574         btrfs_rm_dev_replace_blocked(fs_info);
 575
 576         btrfs_rm_dev_replace_srcdev(fs_info, src_device);
 577
 578         btrfs_rm_dev_replace_unblocked(fs_info);
 579
 580         /*
 581          * this is again a consistent state where no dev_replace procedure
 582          * is running, the target device is part of the filesystem, the
 583          * source device is not part of the filesystem anymore and its 1st
 584          * superblock is scratched out so that it is no longer marked to
 585          * belong to this filesystem.
 586          */
 587         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 588         mutex_unlock(&root->fs_info->chunk_mutex);
 589
 590         /* write back the superblocks */
 591         trans = btrfs_start_transaction(root, 0);
 592         if (!IS_ERR(trans))
 593                 btrfs_commit_transaction(trans, root);
 594
 595         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 596
 597         return 0;
 598 }
 599
 600 static void btrfs_dev_replace_update_device_in_mapping_tree(
 601                                                 struct btrfs_fs_info *fs_info,
 602                                                 struct btrfs_device *srcdev,
 603                                                 struct btrfs_device *tgtdev)
 604 {
 605         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 606         struct extent_map *em;
 607         struct map_lookup *map;
 608         u64 start = 0;
 609         int i;
 610
 611         write_lock(&em_tree->lock);
 612         do {
 613                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 614                 if (!em)
 615                         break;
 616                 map = (struct map_lookup *)em->bdev;
 617                 for (i = 0; i < map->num_stripes; i++)
 618                         if (srcdev == map->stripes[i].dev)
 619                                 map->stripes[i].dev = tgtdev;
 620                 start = em->start + em->len;
 621                 free_extent_map(em);
 622         } while (start);
 623         write_unlock(&em_tree->lock);
 624 }
 625
 626 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
 627                                          char *srcdev_name,
 628                                          struct btrfs_device **device)
 629 {
 630         int ret;
 631
 632         if (srcdevid) {
 633                 ret = 0;
 634                 *device = btrfs_find_device(root->fs_info, srcdevid, NULL,
 635                                             NULL);
 636                 if (!*device)
 637                         ret = -ENOENT;
 638         } else {
 639                 ret = btrfs_find_device_missing_or_by_path(root, srcdev_name,
 640                                                            device);
 641         }
 642         return ret;
 643 }
 644
 645 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 646                               struct btrfs_ioctl_dev_replace_args *args)
 647 {
 648         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 649
 650         btrfs_dev_replace_lock(dev_replace);
 651         /* even if !dev_replace_is_valid, the values are good enough for
 652          * the replace_status ioctl */
 653         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 654         args->status.replace_state = dev_replace->replace_state;
 655         args->status.time_started = dev_replace->time_started;
 656         args->status.time_stopped = dev_replace->time_stopped;
 657         args->status.num_write_errors =
 658                 atomic64_read(&dev_replace->num_write_errors);
 659         args->status.num_uncorrectable_read_errors =
 660                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 661         switch (dev_replace->replace_state) {
 662         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 663         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 664                 args->status.progress_1000 = 0;
 665                 break;
 666         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 667                 args->status.progress_1000 = 1000;
 668                 break;
 669         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 670         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 671                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
 672                         div64_u64(dev_replace->srcdev->total_bytes, 1000));
 673                 break;
 674         }
 675         btrfs_dev_replace_unlock(dev_replace);
 676 }
 677
 678 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 679                              struct btrfs_ioctl_dev_replace_args *args)
 680 {
 681         args->result = __btrfs_dev_replace_cancel(fs_info);
 682         return 0;
 683 }
 684
 685 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 686 {
 687         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 688         struct btrfs_device *tgt_device = NULL;
 689         struct btrfs_trans_handle *trans;
 690         struct btrfs_root *root = fs_info->tree_root;
 691         u64 result;
 692         int ret;
 693
 694         if (fs_info->sb->s_flags & MS_RDONLY)
 695                 return -EROFS;
 696
 697         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 698         btrfs_dev_replace_lock(dev_replace);
 699         switch (dev_replace->replace_state) {
 700         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 701         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 702         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 703                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 704                 btrfs_dev_replace_unlock(dev_replace);
 705                 goto leave;
 706         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 707         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 708                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 709                 tgt_device = dev_replace->tgtdev;
 710                 dev_replace->tgtdev = NULL;
 711                 dev_replace->srcdev = NULL;
 712                 break;
 713         }
 714         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 715         dev_replace->time_stopped = get_seconds();
 716         dev_replace->item_needs_writeback = 1;
 717         btrfs_dev_replace_unlock(dev_replace);
 718         btrfs_scrub_cancel(fs_info);
 719
 720         trans = btrfs_start_transaction(root, 0);
 721         if (IS_ERR(trans)) {
 722                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 723                 return PTR_ERR(trans);
 724         }
 725         ret = btrfs_commit_transaction(trans, root);
 726         WARN_ON(ret);
 727         if (tgt_device)
 728                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 729
 730 leave:
 731         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 732         return result;
 733 }
 734
 735 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 736 {
 737         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 738
 739         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 740         btrfs_dev_replace_lock(dev_replace);
 741         switch (dev_replace->replace_state) {
 742         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 743         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 744         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 745         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 746                 break;
 747         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 748                 dev_replace->replace_state =
 749                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 750                 dev_replace->time_stopped = get_seconds();
 751                 dev_replace->item_needs_writeback = 1;
 752                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 753                 break;
 754         }
 755
 756         btrfs_dev_replace_unlock(dev_replace);
 757         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 758 }
 759
 760 /* resume dev_replace procedure that was interrupted by unmount */
 761 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 762 {
 763         struct task_struct *task;
 764         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 765
 766         btrfs_dev_replace_lock(dev_replace);
 767         switch (dev_replace->replace_state) {
 768         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 769         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 770         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 771                 btrfs_dev_replace_unlock(dev_replace);
 772                 return 0;
 773         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 774                 break;
 775         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 776                 dev_replace->replace_state =
 777                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 778                 break;
 779         }
 780         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 781                 btrfs_info(fs_info, "cannot continue dev_replace, tgtdev is missing");
 782                 btrfs_info(fs_info,
 783                         "you may cancel the operation after 'mount -o degraded'");
 784                 btrfs_dev_replace_unlock(dev_replace);
 785                 return 0;
 786         }
 787         btrfs_dev_replace_unlock(dev_replace);
 788
 789         WARN_ON(atomic_xchg(
 790                 &fs_info->mutually_exclusive_operation_running, 1));
 791         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 792         return PTR_ERR_OR_ZERO(task);
 793 }
 794
 795 static int btrfs_dev_replace_kthread(void *data)
 796 {
 797         struct btrfs_fs_info *fs_info = data;
 798         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 799         struct btrfs_ioctl_dev_replace_args *status_args;
 800         u64 progress;
 801
 802         status_args = kzalloc(sizeof(*status_args), GFP_NOFS);
 803         if (status_args) {
 804                 btrfs_dev_replace_status(fs_info, status_args);
 805                 progress = status_args->status.progress_1000;
 806                 kfree(status_args);
 807                 do_div(progress, 10);
 808                 printk_in_rcu(KERN_INFO
 809                         "BTRFS: continuing dev_replace from %s (devid %llu) to %s @%u%%\n",
 810                         dev_replace->srcdev->missing ? "<missing disk>" :
 811                         rcu_str_deref(dev_replace->srcdev->name),
 812                         dev_replace->srcdev->devid,
 813                         dev_replace->tgtdev ?
 814                         rcu_str_deref(dev_replace->tgtdev->name) :
 815                         "<missing target disk>",
 816                         (unsigned int)progress);
 817         }
 818         btrfs_dev_replace_continue_on_mount(fs_info);
 819         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
 820
 821         return 0;
 822 }
 823
 824 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 825 {
 826         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 827         int ret;
 828
 829         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 830                               dev_replace->committed_cursor_left,
 831                               dev_replace->srcdev->total_bytes,
 832                               &dev_replace->scrub_progress, 0, 1);
 833         ret = btrfs_dev_replace_finishing(fs_info, ret);
 834         WARN_ON(ret);
 835         return 0;
 836 }
 837
 838 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 839 {
 840         if (!dev_replace->is_valid)
 841                 return 0;
 842
 843         switch (dev_replace->replace_state) {
 844         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 845         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 846         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 847                 return 0;
 848         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 849         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 850                 /*
 851                  * return true even if tgtdev is missing (this is
 852                  * something that can happen if the dev_replace
 853                  * procedure is suspended by an umount and then
 854                  * the tgtdev is missing (or "btrfs dev scan") was
 855                  * not called and the the filesystem is remounted
 856                  * in degraded state. This does not stop the
 857                  * dev_replace procedure. It needs to be canceled
 858                  * manually if the cancelation is wanted.
 859                  */
 860                 break;
 861         }
 862         return 1;
 863 }
 864
 865 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
 866 {
 867         /* the beginning is just an optimization for the typical case */
 868         if (atomic_read(&dev_replace->nesting_level) == 0) {
 869 acquire_lock:
 870                 /* this is not a nested case where the same thread
 871                  * is trying to acqurire the same lock twice */
 872                 mutex_lock(&dev_replace->lock);
 873                 mutex_lock(&dev_replace->lock_management_lock);
 874                 dev_replace->lock_owner = current->pid;
 875                 atomic_inc(&dev_replace->nesting_level);
 876                 mutex_unlock(&dev_replace->lock_management_lock);
 877                 return;
 878         }
 879
 880         mutex_lock(&dev_replace->lock_management_lock);
 881         if (atomic_read(&dev_replace->nesting_level) > 0 &&
 882             dev_replace->lock_owner == current->pid) {
 883                 WARN_ON(!mutex_is_locked(&dev_replace->lock));
 884                 atomic_inc(&dev_replace->nesting_level);
 885                 mutex_unlock(&dev_replace->lock_management_lock);
 886                 return;
 887         }
 888
 889         mutex_unlock(&dev_replace->lock_management_lock);
 890         goto acquire_lock;
 891 }
 892
 893 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
 894 {
 895         WARN_ON(!mutex_is_locked(&dev_replace->lock));
 896         mutex_lock(&dev_replace->lock_management_lock);
 897         WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
 898         WARN_ON(dev_replace->lock_owner != current->pid);
 899         atomic_dec(&dev_replace->nesting_level);
 900         if (atomic_read(&dev_replace->nesting_level) == 0) {
 901                 dev_replace->lock_owner = 0;
 902                 mutex_unlock(&dev_replace->lock_management_lock);
 903                 mutex_unlock(&dev_replace->lock);
 904         } else {
 905                 mutex_unlock(&dev_replace->lock_management_lock);
 906         }
 907 }
 908
 909 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
 910 {
 911         percpu_counter_inc(&fs_info->bio_counter);
 912 }
 913
 914 void btrfs_bio_counter_dec(struct btrfs_fs_info *fs_info)
 915 {
 916         percpu_counter_dec(&fs_info->bio_counter);
 917
 918         if (waitqueue_active(&fs_info->replace_wait))
 919                 wake_up(&fs_info->replace_wait);
 920 }
 921
 922 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
 923 {
 924         DEFINE_WAIT(wait);
 925 again:
 926         percpu_counter_inc(&fs_info->bio_counter);
 927         if (test_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state)) {
 928                 btrfs_bio_counter_dec(fs_info);
 929                 wait_event(fs_info->replace_wait,
 930                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 931                                      &fs_info->fs_state));
 932                 goto again;
 933         }
 934
 935 }