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 /*
 435  * blocked until all flighting bios are finished.
 436  */
 437 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 438 {
 439         s64 writers;
 440         DEFINE_WAIT(wait);
 441
 442         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 443         do {
 444                 prepare_to_wait(&fs_info->replace_wait, &wait,
 445                                 TASK_UNINTERRUPTIBLE);
 446                 writers = percpu_counter_sum(&fs_info->bio_counter);
 447                 if (writers)
 448                         schedule();
 449                 finish_wait(&fs_info->replace_wait, &wait);
 450         } while (writers);
 451 }
 452
 453 /*
 454  * we have removed target device, it is safe to allow new bios request.
 455  */
 456 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 457 {
 458         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 459         if (waitqueue_active(&fs_info->replace_wait))
 460                 wake_up(&fs_info->replace_wait);
 461 }
 462
 463 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 464                                        int scrub_ret)
 465 {
 466         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 467         struct btrfs_device *tgt_device;
 468         struct btrfs_device *src_device;
 469         struct btrfs_root *root = fs_info->tree_root;
 470         u8 uuid_tmp[BTRFS_UUID_SIZE];
 471         struct btrfs_trans_handle *trans;
 472         int ret = 0;
 473
 474         /* don't allow cancel or unmount to disturb the finishing procedure */
 475         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 476
 477         btrfs_dev_replace_lock(dev_replace);
 478         /* was the operation canceled, or is it finished? */
 479         if (dev_replace->replace_state !=
 480             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 481                 btrfs_dev_replace_unlock(dev_replace);
 482                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 483                 return 0;
 484         }
 485
 486         tgt_device = dev_replace->tgtdev;
 487         src_device = dev_replace->srcdev;
 488         btrfs_dev_replace_unlock(dev_replace);
 489
 490         /*
 491          * flush all outstanding I/O and inode extent mappings before the
 492          * copy operation is declared as being finished
 493          */
 494         ret = btrfs_start_delalloc_roots(root->fs_info, 0, -1);
 495         if (ret) {
 496                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 497                 return ret;
 498         }
 499         btrfs_wait_ordered_roots(root->fs_info, -1);
 500
 501         trans = btrfs_start_transaction(root, 0);
 502         if (IS_ERR(trans)) {
 503                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 504                 return PTR_ERR(trans);
 505         }
 506         ret = btrfs_commit_transaction(trans, root);
 507         WARN_ON(ret);
 508
 509         /* keep away write_all_supers() during the finishing procedure */
 510         mutex_lock(&root->fs_info->chunk_mutex);
 511         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
 512         btrfs_dev_replace_lock(dev_replace);
 513         dev_replace->replace_state =
 514                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 515                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 516         dev_replace->tgtdev = NULL;
 517         dev_replace->srcdev = NULL;
 518         dev_replace->time_stopped = get_seconds();
 519         dev_replace->item_needs_writeback = 1;
 520
 521         /* replace old device with new one in mapping tree */
 522         if (!scrub_ret) {
 523                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 524                                                                 src_device,
 525                                                                 tgt_device);
 526         } else {
 527                 printk_in_rcu(KERN_ERR
 528                               "BTRFS: btrfs_scrub_dev(%s, %llu, %s) failed %d\n",
 529                               src_device->missing ? "<missing disk>" :
 530                                 rcu_str_deref(src_device->name),
 531                               src_device->devid,
 532                               rcu_str_deref(tgt_device->name), scrub_ret);
 533                 btrfs_dev_replace_unlock(dev_replace);
 534                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 535                 mutex_unlock(&root->fs_info->chunk_mutex);
 536                 if (tgt_device)
 537                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 538                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 539
 540                 return 0;
 541         }
 542
 543         printk_in_rcu(KERN_INFO
 544                       "BTRFS: dev_replace from %s (devid %llu) to %s) finished\n",
 545                       src_device->missing ? "<missing disk>" :
 546                         rcu_str_deref(src_device->name),
 547                       src_device->devid,
 548                       rcu_str_deref(tgt_device->name));
 549         tgt_device->is_tgtdev_for_dev_replace = 0;
 550         tgt_device->devid = src_device->devid;
 551         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 552         tgt_device->bytes_used = src_device->bytes_used;
 553         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 554         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 555         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 556         tgt_device->total_bytes = src_device->total_bytes;
 557         tgt_device->disk_total_bytes = src_device->disk_total_bytes;
 558         tgt_device->bytes_used = src_device->bytes_used;
 559         if (fs_info->sb->s_bdev == src_device->bdev)
 560                 fs_info->sb->s_bdev = tgt_device->bdev;
 561         if (fs_info->fs_devices->latest_bdev == src_device->bdev)
 562                 fs_info->fs_devices->latest_bdev = tgt_device->bdev;
 563         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 564
 565         btrfs_rm_dev_replace_blocked(fs_info);
 566
 567         btrfs_rm_dev_replace_srcdev(fs_info, src_device);
 568
 569         btrfs_rm_dev_replace_unblocked(fs_info);
 570
 571         /*
 572          * this is again a consistent state where no dev_replace procedure
 573          * is running, the target device is part of the filesystem, the
 574          * source device is not part of the filesystem anymore and its 1st
 575          * superblock is scratched out so that it is no longer marked to
 576          * belong to this filesystem.
 577          */
 578         btrfs_dev_replace_unlock(dev_replace);
 579         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 580         mutex_unlock(&root->fs_info->chunk_mutex);
 581
 582         /* write back the superblocks */
 583         trans = btrfs_start_transaction(root, 0);
 584         if (!IS_ERR(trans))
 585                 btrfs_commit_transaction(trans, root);
 586
 587         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 588
 589         return 0;
 590 }
 591
 592 static void btrfs_dev_replace_update_device_in_mapping_tree(
 593                                                 struct btrfs_fs_info *fs_info,
 594                                                 struct btrfs_device *srcdev,
 595                                                 struct btrfs_device *tgtdev)
 596 {
 597         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
 598         struct extent_map *em;
 599         struct map_lookup *map;
 600         u64 start = 0;
 601         int i;
 602
 603         write_lock(&em_tree->lock);
 604         do {
 605                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
 606                 if (!em)
 607                         break;
 608                 map = (struct map_lookup *)em->bdev;
 609                 for (i = 0; i < map->num_stripes; i++)
 610                         if (srcdev == map->stripes[i].dev)
 611                                 map->stripes[i].dev = tgtdev;
 612                 start = em->start + em->len;
 613                 free_extent_map(em);
 614         } while (start);
 615         write_unlock(&em_tree->lock);
 616 }
 617
 618 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
 619                                          char *srcdev_name,
 620                                          struct btrfs_device **device)
 621 {
 622         int ret;
 623
 624         if (srcdevid) {
 625                 ret = 0;
 626                 *device = btrfs_find_device(root->fs_info, srcdevid, NULL,
 627                                             NULL);
 628                 if (!*device)
 629                         ret = -ENOENT;
 630         } else {
 631                 ret = btrfs_find_device_missing_or_by_path(root, srcdev_name,
 632                                                            device);
 633         }
 634         return ret;
 635 }
 636
 637 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 638                               struct btrfs_ioctl_dev_replace_args *args)
 639 {
 640         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 641
 642         btrfs_dev_replace_lock(dev_replace);
 643         /* even if !dev_replace_is_valid, the values are good enough for
 644          * the replace_status ioctl */
 645         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 646         args->status.replace_state = dev_replace->replace_state;
 647         args->status.time_started = dev_replace->time_started;
 648         args->status.time_stopped = dev_replace->time_stopped;
 649         args->status.num_write_errors =
 650                 atomic64_read(&dev_replace->num_write_errors);
 651         args->status.num_uncorrectable_read_errors =
 652                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 653         switch (dev_replace->replace_state) {
 654         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 655         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 656                 args->status.progress_1000 = 0;
 657                 break;
 658         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 659                 args->status.progress_1000 = 1000;
 660                 break;
 661         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 662         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 663                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
 664                         div64_u64(dev_replace->srcdev->total_bytes, 1000));
 665                 break;
 666         }
 667         btrfs_dev_replace_unlock(dev_replace);
 668 }
 669
 670 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 671                              struct btrfs_ioctl_dev_replace_args *args)
 672 {
 673         args->result = __btrfs_dev_replace_cancel(fs_info);
 674         return 0;
 675 }
 676
 677 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 678 {
 679         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 680         struct btrfs_device *tgt_device = NULL;
 681         struct btrfs_trans_handle *trans;
 682         struct btrfs_root *root = fs_info->tree_root;
 683         u64 result;
 684         int ret;
 685
 686         if (fs_info->sb->s_flags & MS_RDONLY)
 687                 return -EROFS;
 688
 689         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 690         btrfs_dev_replace_lock(dev_replace);
 691         switch (dev_replace->replace_state) {
 692         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 693         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 694         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 695                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
 696                 btrfs_dev_replace_unlock(dev_replace);
 697                 goto leave;
 698         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 699         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 700                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 701                 tgt_device = dev_replace->tgtdev;
 702                 dev_replace->tgtdev = NULL;
 703                 dev_replace->srcdev = NULL;
 704                 break;
 705         }
 706         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 707         dev_replace->time_stopped = get_seconds();
 708         dev_replace->item_needs_writeback = 1;
 709         btrfs_dev_replace_unlock(dev_replace);
 710         btrfs_scrub_cancel(fs_info);
 711
 712         trans = btrfs_start_transaction(root, 0);
 713         if (IS_ERR(trans)) {
 714                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 715                 return PTR_ERR(trans);
 716         }
 717         ret = btrfs_commit_transaction(trans, root);
 718         WARN_ON(ret);
 719         if (tgt_device)
 720                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 721
 722 leave:
 723         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 724         return result;
 725 }
 726
 727 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 728 {
 729         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 730
 731         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 732         btrfs_dev_replace_lock(dev_replace);
 733         switch (dev_replace->replace_state) {
 734         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 735         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 736         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 737         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 738                 break;
 739         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 740                 dev_replace->replace_state =
 741                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
 742                 dev_replace->time_stopped = get_seconds();
 743                 dev_replace->item_needs_writeback = 1;
 744                 btrfs_info(fs_info, "suspending dev_replace for unmount");
 745                 break;
 746         }
 747
 748         btrfs_dev_replace_unlock(dev_replace);
 749         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 750 }
 751
 752 /* resume dev_replace procedure that was interrupted by unmount */
 753 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 754 {
 755         struct task_struct *task;
 756         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 757
 758         btrfs_dev_replace_lock(dev_replace);
 759         switch (dev_replace->replace_state) {
 760         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 761         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 762         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 763                 btrfs_dev_replace_unlock(dev_replace);
 764                 return 0;
 765         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 766                 break;
 767         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 768                 dev_replace->replace_state =
 769                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 770                 break;
 771         }
 772         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
 773                 btrfs_info(fs_info, "cannot continue dev_replace, tgtdev is missing");
 774                 btrfs_info(fs_info,
 775                         "you may cancel the operation after 'mount -o degraded'");
 776                 btrfs_dev_replace_unlock(dev_replace);
 777                 return 0;
 778         }
 779         btrfs_dev_replace_unlock(dev_replace);
 780
 781         WARN_ON(atomic_xchg(
 782                 &fs_info->mutually_exclusive_operation_running, 1));
 783         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
 784         return PTR_ERR_OR_ZERO(task);
 785 }
 786
 787 static int btrfs_dev_replace_kthread(void *data)
 788 {
 789         struct btrfs_fs_info *fs_info = data;
 790         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 791         struct btrfs_ioctl_dev_replace_args *status_args;
 792         u64 progress;
 793
 794         status_args = kzalloc(sizeof(*status_args), GFP_NOFS);
 795         if (status_args) {
 796                 btrfs_dev_replace_status(fs_info, status_args);
 797                 progress = status_args->status.progress_1000;
 798                 kfree(status_args);
 799                 do_div(progress, 10);
 800                 printk_in_rcu(KERN_INFO
 801                         "BTRFS: continuing dev_replace from %s (devid %llu) to %s @%u%%\n",
 802                         dev_replace->srcdev->missing ? "<missing disk>" :
 803                         rcu_str_deref(dev_replace->srcdev->name),
 804                         dev_replace->srcdev->devid,
 805                         dev_replace->tgtdev ?
 806                         rcu_str_deref(dev_replace->tgtdev->name) :
 807                         "<missing target disk>",
 808                         (unsigned int)progress);
 809         }
 810         btrfs_dev_replace_continue_on_mount(fs_info);
 811         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
 812
 813         return 0;
 814 }
 815
 816 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 817 {
 818         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 819         int ret;
 820
 821         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
 822                               dev_replace->committed_cursor_left,
 823                               dev_replace->srcdev->total_bytes,
 824                               &dev_replace->scrub_progress, 0, 1);
 825         ret = btrfs_dev_replace_finishing(fs_info, ret);
 826         WARN_ON(ret);
 827         return 0;
 828 }
 829
 830 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 831 {
 832         if (!dev_replace->is_valid)
 833                 return 0;
 834
 835         switch (dev_replace->replace_state) {
 836         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 837         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 838         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 839                 return 0;
 840         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 841         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 842                 /*
 843                  * return true even if tgtdev is missing (this is
 844                  * something that can happen if the dev_replace
 845                  * procedure is suspended by an umount and then
 846                  * the tgtdev is missing (or "btrfs dev scan") was
 847                  * not called and the the filesystem is remounted
 848                  * in degraded state. This does not stop the
 849                  * dev_replace procedure. It needs to be canceled
 850                  * manually if the cancelation is wanted.
 851                  */
 852                 break;
 853         }
 854         return 1;
 855 }
 856
 857 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
 858 {
 859         /* the beginning is just an optimization for the typical case */
 860         if (atomic_read(&dev_replace->nesting_level) == 0) {
 861 acquire_lock:
 862                 /* this is not a nested case where the same thread
 863                  * is trying to acqurire the same lock twice */
 864                 mutex_lock(&dev_replace->lock);
 865                 mutex_lock(&dev_replace->lock_management_lock);
 866                 dev_replace->lock_owner = current->pid;
 867                 atomic_inc(&dev_replace->nesting_level);
 868                 mutex_unlock(&dev_replace->lock_management_lock);
 869                 return;
 870         }
 871
 872         mutex_lock(&dev_replace->lock_management_lock);
 873         if (atomic_read(&dev_replace->nesting_level) > 0 &&
 874             dev_replace->lock_owner == current->pid) {
 875                 WARN_ON(!mutex_is_locked(&dev_replace->lock));
 876                 atomic_inc(&dev_replace->nesting_level);
 877                 mutex_unlock(&dev_replace->lock_management_lock);
 878                 return;
 879         }
 880
 881         mutex_unlock(&dev_replace->lock_management_lock);
 882         goto acquire_lock;
 883 }
 884
 885 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
 886 {
 887         WARN_ON(!mutex_is_locked(&dev_replace->lock));
 888         mutex_lock(&dev_replace->lock_management_lock);
 889         WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
 890         WARN_ON(dev_replace->lock_owner != current->pid);
 891         atomic_dec(&dev_replace->nesting_level);
 892         if (atomic_read(&dev_replace->nesting_level) == 0) {
 893                 dev_replace->lock_owner = 0;
 894                 mutex_unlock(&dev_replace->lock_management_lock);
 895                 mutex_unlock(&dev_replace->lock);
 896         } else {
 897                 mutex_unlock(&dev_replace->lock_management_lock);
 898         }
 899 }
 900
 901 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
 902 {
 903         percpu_counter_inc(&fs_info->bio_counter);
 904 }
 905
 906 void btrfs_bio_counter_dec(struct btrfs_fs_info *fs_info)
 907 {
 908         percpu_counter_dec(&fs_info->bio_counter);
 909
 910         if (waitqueue_active(&fs_info->replace_wait))
 911                 wake_up(&fs_info->replace_wait);
 912 }
 913
 914 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
 915 {
 916         DEFINE_WAIT(wait);
 917 again:
 918         percpu_counter_inc(&fs_info->bio_counter);
 919         if (test_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state)) {
 920                 btrfs_bio_counter_dec(fs_info);
 921                 wait_event(fs_info->replace_wait,
 922                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
 923                                      &fs_info->fs_state));
 924                 goto again;
 925         }
 926
 927 }