1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) STRATO AG 2012.  All rights reserved.
   4 */
   5
   6#include <linux/sched.h>
   7#include <linux/bio.h>
   8#include <linux/slab.h>
   9#include <linux/blkdev.h>
  10#include <linux/kthread.h>
  11#include <linux/math64.h>
  12#include "misc.h"
  13#include "ctree.h"
 
  14#include "disk-io.h"
  15#include "transaction.h"
 
  16#include "volumes.h"
  17#include "async-thread.h"
 
 
  18#include "dev-replace.h"
  19#include "sysfs.h"
  20#include "zoned.h"
  21#include "block-group.h"
  22#include "fs.h"
  23#include "accessors.h"
  24#include "scrub.h"
  25
  26/*
  27 * Device replace overview
  28 *
  29 * [Objective]
  30 * To copy all extents (both new and on-disk) from source device to target
  31 * device, while still keeping the filesystem read-write.
  32 *
  33 * [Method]
  34 * There are two main methods involved:
  35 *
  36 * - Write duplication
  37 *
  38 *   All new writes will be written to both target and source devices, so even
  39 *   if replace gets canceled, sources device still contains up-to-date data.
  40 *
  41 *   Location:		handle_ops_on_dev_replace() from btrfs_map_block()
  42 *   Start:		btrfs_dev_replace_start()
  43 *   End:		btrfs_dev_replace_finishing()
  44 *   Content:		Latest data/metadata
  45 *
  46 * - Copy existing extents
  47 *
  48 *   This happens by re-using scrub facility, as scrub also iterates through
  49 *   existing extents from commit root.
  50 *
  51 *   Location:		scrub_write_block_to_dev_replace() from
  52 *   			scrub_block_complete()
  53 *   Content:		Data/meta from commit root.
  54 *
  55 * Due to the content difference, we need to avoid nocow write when dev-replace
  56 * is happening.  This is done by marking the block group read-only and waiting
  57 * for NOCOW writes.
  58 *
  59 * After replace is done, the finishing part is done by swapping the target and
  60 * source devices.
  61 *
  62 *   Location:		btrfs_dev_replace_update_device_in_mapping_tree() from
  63 *   			btrfs_dev_replace_finishing()
  64 */
  65
  66static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
  67				       int scrub_ret);
 
 
 
 
  68static int btrfs_dev_replace_kthread(void *data);
  69
  70int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
  71{
  72	struct btrfs_dev_lookup_args args = { .devid = BTRFS_DEV_REPLACE_DEVID };
  73	struct btrfs_key key;
  74	struct btrfs_root *dev_root = fs_info->dev_root;
  75	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
  76	struct extent_buffer *eb;
  77	int slot;
  78	int ret = 0;
  79	struct btrfs_path *path = NULL;
  80	int item_size;
  81	struct btrfs_dev_replace_item *ptr;
  82	u64 src_devid;
  83
  84	if (!dev_root)
  85		return 0;
  86
  87	path = btrfs_alloc_path();
  88	if (!path) {
  89		ret = -ENOMEM;
  90		goto out;
  91	}
  92
  93	key.objectid = 0;
  94	key.type = BTRFS_DEV_REPLACE_KEY;
  95	key.offset = 0;
  96	ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
  97	if (ret) {
  98no_valid_dev_replace_entry_found:
  99		/*
 100		 * We don't have a replace item or it's corrupted.  If there is
 101		 * a replace target, fail the mount.
 102		 */
 103		if (btrfs_find_device(fs_info->fs_devices, &args)) {
 104			btrfs_err(fs_info,
 105			"found replace target device without a valid replace item");
 106			ret = -EUCLEAN;
 107			goto out;
 108		}
 109		ret = 0;
 110		dev_replace->replace_state =
 111			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 112		dev_replace->cont_reading_from_srcdev_mode =
 113		    BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
 114		dev_replace->time_started = 0;
 115		dev_replace->time_stopped = 0;
 116		atomic64_set(&dev_replace->num_write_errors, 0);
 117		atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 118		dev_replace->cursor_left = 0;
 119		dev_replace->committed_cursor_left = 0;
 120		dev_replace->cursor_left_last_write_of_item = 0;
 121		dev_replace->cursor_right = 0;
 122		dev_replace->srcdev = NULL;
 123		dev_replace->tgtdev = NULL;
 124		dev_replace->is_valid = 0;
 125		dev_replace->item_needs_writeback = 0;
 126		goto out;
 127	}
 128	slot = path->slots[0];
 129	eb = path->nodes[0];
 130	item_size = btrfs_item_size(eb, slot);
 131	ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
 132
 133	if (item_size != sizeof(struct btrfs_dev_replace_item)) {
 134		btrfs_warn(fs_info,
 135			"dev_replace entry found has unexpected size, ignore entry");
 136		goto no_valid_dev_replace_entry_found;
 137	}
 138
 139	src_devid = btrfs_dev_replace_src_devid(eb, ptr);
 140	dev_replace->cont_reading_from_srcdev_mode =
 141		btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
 142	dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
 143	dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
 144	dev_replace->time_stopped =
 145		btrfs_dev_replace_time_stopped(eb, ptr);
 146	atomic64_set(&dev_replace->num_write_errors,
 147		     btrfs_dev_replace_num_write_errors(eb, ptr));
 148	atomic64_set(&dev_replace->num_uncorrectable_read_errors,
 149		     btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
 150	dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
 151	dev_replace->committed_cursor_left = dev_replace->cursor_left;
 152	dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
 153	dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
 154	dev_replace->is_valid = 1;
 155
 156	dev_replace->item_needs_writeback = 0;
 157	switch (dev_replace->replace_state) {
 158	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 159	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 160	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 161		/*
 162		 * We don't have an active replace item but if there is a
 163		 * replace target, fail the mount.
 164		 */
 165		if (btrfs_find_device(fs_info->fs_devices, &args)) {
 166			btrfs_err(fs_info,
 167"replace without active item, run 'device scan --forget' on the target device");
 168			ret = -EUCLEAN;
 169		} else {
 170			dev_replace->srcdev = NULL;
 171			dev_replace->tgtdev = NULL;
 172		}
 173		break;
 174	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 175	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 176		dev_replace->tgtdev = btrfs_find_device(fs_info->fs_devices, &args);
 177		args.devid = src_devid;
 178		dev_replace->srcdev = btrfs_find_device(fs_info->fs_devices, &args);
 179
 
 180		/*
 181		 * allow 'btrfs dev replace_cancel' if src/tgt device is
 182		 * missing
 183		 */
 184		if (!dev_replace->srcdev &&
 185		    !btrfs_test_opt(fs_info, DEGRADED)) {
 186			ret = -EIO;
 187			btrfs_warn(fs_info,
 188			   "cannot mount because device replace operation is ongoing and");
 189			btrfs_warn(fs_info,
 190			   "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 191			   src_devid);
 192		}
 193		if (!dev_replace->tgtdev &&
 194		    !btrfs_test_opt(fs_info, DEGRADED)) {
 195			ret = -EIO;
 196			btrfs_warn(fs_info,
 197			   "cannot mount because device replace operation is ongoing and");
 198			btrfs_warn(fs_info,
 199			   "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
 200				BTRFS_DEV_REPLACE_DEVID);
 201		}
 202		if (dev_replace->tgtdev) {
 203			if (dev_replace->srcdev) {
 204				dev_replace->tgtdev->total_bytes =
 205					dev_replace->srcdev->total_bytes;
 206				dev_replace->tgtdev->disk_total_bytes =
 207					dev_replace->srcdev->disk_total_bytes;
 208				dev_replace->tgtdev->commit_total_bytes =
 209					dev_replace->srcdev->commit_total_bytes;
 210				dev_replace->tgtdev->bytes_used =
 211					dev_replace->srcdev->bytes_used;
 212				dev_replace->tgtdev->commit_bytes_used =
 213					dev_replace->srcdev->commit_bytes_used;
 214			}
 215			set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
 216				&dev_replace->tgtdev->dev_state);
 217
 218			WARN_ON(fs_info->fs_devices->rw_devices == 0);
 219			dev_replace->tgtdev->io_width = fs_info->sectorsize;
 220			dev_replace->tgtdev->io_align = fs_info->sectorsize;
 221			dev_replace->tgtdev->sector_size = fs_info->sectorsize;
 222			dev_replace->tgtdev->fs_info = fs_info;
 223			set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
 224				&dev_replace->tgtdev->dev_state);
 225		}
 226		break;
 227	}
 228
 229out:
 230	btrfs_free_path(path);
 231	return ret;
 232}
 233
 234/*
 235 * Initialize a new device for device replace target from a given source dev
 236 * and path.
 237 *
 238 * Return 0 and new device in @device_out, otherwise return < 0
 239 */
 240static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 241				  const char *device_path,
 242				  struct btrfs_device *srcdev,
 243				  struct btrfs_device **device_out)
 244{
 245	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 246	struct btrfs_device *device;
 247	struct file *bdev_file;
 248	struct block_device *bdev;
 
 
 249	u64 devid = BTRFS_DEV_REPLACE_DEVID;
 250	int ret = 0;
 251
 252	*device_out = NULL;
 253	if (srcdev->fs_devices->seeding) {
 254		btrfs_err(fs_info, "the filesystem is a seed filesystem!");
 255		return -EINVAL;
 256	}
 257
 258	bdev_file = bdev_file_open_by_path(device_path, BLK_OPEN_WRITE,
 259					fs_info->bdev_holder, NULL);
 260	if (IS_ERR(bdev_file)) {
 261		btrfs_err(fs_info, "target device %s is invalid!", device_path);
 262		return PTR_ERR(bdev_file);
 263	}
 264	bdev = file_bdev(bdev_file);
 265
 266	if (!btrfs_check_device_zone_type(fs_info, bdev)) {
 267		btrfs_err(fs_info,
 268		"dev-replace: zoned type of target device mismatch with filesystem");
 269		ret = -EINVAL;
 270		goto error;
 271	}
 272
 273	sync_blockdev(bdev);
 274
 275	list_for_each_entry(device, &fs_devices->devices, dev_list) {
 
 276		if (device->bdev == bdev) {
 277			btrfs_err(fs_info,
 278				  "target device is in the filesystem!");
 279			ret = -EEXIST;
 280			goto error;
 281		}
 282	}
 283
 284
 285	if (bdev_nr_bytes(bdev) < btrfs_device_get_total_bytes(srcdev)) {
 
 286		btrfs_err(fs_info,
 287			  "target device is smaller than source device!");
 288		ret = -EINVAL;
 289		goto error;
 290	}
 291
 292
 293	device = btrfs_alloc_device(NULL, &devid, NULL, device_path);
 294	if (IS_ERR(device)) {
 295		ret = PTR_ERR(device);
 296		goto error;
 297	}
 298
 299	ret = lookup_bdev(device_path, &device->devt);
 300	if (ret)
 
 
 301		goto error;
 
 
 302
 303	set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
 304	device->generation = 0;
 305	device->io_width = fs_info->sectorsize;
 306	device->io_align = fs_info->sectorsize;
 307	device->sector_size = fs_info->sectorsize;
 308	device->total_bytes = btrfs_device_get_total_bytes(srcdev);
 309	device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
 310	device->bytes_used = btrfs_device_get_bytes_used(srcdev);
 311	device->commit_total_bytes = srcdev->commit_total_bytes;
 312	device->commit_bytes_used = device->bytes_used;
 313	device->fs_info = fs_info;
 314	device->bdev = bdev;
 315	device->bdev_file = bdev_file;
 316	set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 317	set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 
 318	device->dev_stats_valid = 1;
 319	set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
 320	device->fs_devices = fs_devices;
 321
 322	ret = btrfs_get_dev_zone_info(device, false);
 323	if (ret)
 324		goto error;
 325
 326	mutex_lock(&fs_devices->device_list_mutex);
 327	list_add(&device->dev_list, &fs_devices->devices);
 328	fs_devices->num_devices++;
 329	fs_devices->open_devices++;
 330	mutex_unlock(&fs_devices->device_list_mutex);
 331
 332	*device_out = device;
 333	return 0;
 334
 335error:
 336	fput(bdev_file);
 337	return ret;
 338}
 339
 340/*
 341 * called from commit_transaction. Writes changed device replace state to
 342 * disk.
 343 */
 344int btrfs_run_dev_replace(struct btrfs_trans_handle *trans)
 345{
 346	struct btrfs_fs_info *fs_info = trans->fs_info;
 347	int ret;
 348	struct btrfs_root *dev_root = fs_info->dev_root;
 349	struct btrfs_path *path;
 350	struct btrfs_key key;
 351	struct extent_buffer *eb;
 352	struct btrfs_dev_replace_item *ptr;
 353	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 354
 355	down_read(&dev_replace->rwsem);
 356	if (!dev_replace->is_valid ||
 357	    !dev_replace->item_needs_writeback) {
 358		up_read(&dev_replace->rwsem);
 359		return 0;
 360	}
 361	up_read(&dev_replace->rwsem);
 362
 363	key.objectid = 0;
 364	key.type = BTRFS_DEV_REPLACE_KEY;
 365	key.offset = 0;
 366
 367	path = btrfs_alloc_path();
 368	if (!path) {
 369		ret = -ENOMEM;
 370		goto out;
 371	}
 372	ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
 373	if (ret < 0) {
 374		btrfs_warn(fs_info,
 375			   "error %d while searching for dev_replace item!",
 376			   ret);
 377		goto out;
 378	}
 379
 380	if (ret == 0 &&
 381	    btrfs_item_size(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
 382		/*
 383		 * need to delete old one and insert a new one.
 384		 * Since no attempt is made to recover any old state, if the
 385		 * dev_replace state is 'running', the data on the target
 386		 * drive is lost.
 387		 * It would be possible to recover the state: just make sure
 388		 * that the beginning of the item is never changed and always
 389		 * contains all the essential information. Then read this
 390		 * minimal set of information and use it as a base for the
 391		 * new state.
 392		 */
 393		ret = btrfs_del_item(trans, dev_root, path);
 394		if (ret != 0) {
 395			btrfs_warn(fs_info,
 396				   "delete too small dev_replace item failed %d!",
 397				   ret);
 398			goto out;
 399		}
 400		ret = 1;
 401	}
 402
 403	if (ret == 1) {
 404		/* need to insert a new item */
 405		btrfs_release_path(path);
 406		ret = btrfs_insert_empty_item(trans, dev_root, path,
 407					      &key, sizeof(*ptr));
 408		if (ret < 0) {
 409			btrfs_warn(fs_info,
 410				   "insert dev_replace item failed %d!", ret);
 411			goto out;
 412		}
 413	}
 414
 415	eb = path->nodes[0];
 416	ptr = btrfs_item_ptr(eb, path->slots[0],
 417			     struct btrfs_dev_replace_item);
 418
 419	down_write(&dev_replace->rwsem);
 420	if (dev_replace->srcdev)
 421		btrfs_set_dev_replace_src_devid(eb, ptr,
 422			dev_replace->srcdev->devid);
 423	else
 424		btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
 425	btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
 426		dev_replace->cont_reading_from_srcdev_mode);
 427	btrfs_set_dev_replace_replace_state(eb, ptr,
 428		dev_replace->replace_state);
 429	btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
 430	btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
 431	btrfs_set_dev_replace_num_write_errors(eb, ptr,
 432		atomic64_read(&dev_replace->num_write_errors));
 433	btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
 434		atomic64_read(&dev_replace->num_uncorrectable_read_errors));
 435	dev_replace->cursor_left_last_write_of_item =
 436		dev_replace->cursor_left;
 437	btrfs_set_dev_replace_cursor_left(eb, ptr,
 438		dev_replace->cursor_left_last_write_of_item);
 439	btrfs_set_dev_replace_cursor_right(eb, ptr,
 440		dev_replace->cursor_right);
 441	dev_replace->item_needs_writeback = 0;
 442	up_write(&dev_replace->rwsem);
 443
 444	btrfs_mark_buffer_dirty(trans, eb);
 445
 446out:
 447	btrfs_free_path(path);
 448
 449	return ret;
 450}
 451
 452static int mark_block_group_to_copy(struct btrfs_fs_info *fs_info,
 453				    struct btrfs_device *src_dev)
 454{
 455	struct btrfs_path *path;
 456	struct btrfs_key key;
 457	struct btrfs_key found_key;
 458	struct btrfs_root *root = fs_info->dev_root;
 459	struct btrfs_dev_extent *dev_extent = NULL;
 460	struct btrfs_block_group *cache;
 461	struct btrfs_trans_handle *trans;
 462	int iter_ret = 0;
 463	int ret = 0;
 464	u64 chunk_offset;
 465
 466	/* Do not use "to_copy" on non zoned filesystem for now */
 467	if (!btrfs_is_zoned(fs_info))
 468		return 0;
 469
 470	mutex_lock(&fs_info->chunk_mutex);
 471
 472	/* Ensure we don't have pending new block group */
 473	spin_lock(&fs_info->trans_lock);
 474	while (fs_info->running_transaction &&
 475	       !list_empty(&fs_info->running_transaction->dev_update_list)) {
 476		spin_unlock(&fs_info->trans_lock);
 477		mutex_unlock(&fs_info->chunk_mutex);
 478		trans = btrfs_attach_transaction(root);
 479		if (IS_ERR(trans)) {
 480			ret = PTR_ERR(trans);
 481			mutex_lock(&fs_info->chunk_mutex);
 482			if (ret == -ENOENT) {
 483				spin_lock(&fs_info->trans_lock);
 484				continue;
 485			} else {
 486				goto unlock;
 487			}
 488		}
 489
 490		ret = btrfs_commit_transaction(trans);
 491		mutex_lock(&fs_info->chunk_mutex);
 492		if (ret)
 493			goto unlock;
 494
 495		spin_lock(&fs_info->trans_lock);
 496	}
 497	spin_unlock(&fs_info->trans_lock);
 498
 499	path = btrfs_alloc_path();
 500	if (!path) {
 501		ret = -ENOMEM;
 502		goto unlock;
 503	}
 504
 505	path->reada = READA_FORWARD;
 506	path->search_commit_root = 1;
 507	path->skip_locking = 1;
 508
 509	key.objectid = src_dev->devid;
 510	key.type = BTRFS_DEV_EXTENT_KEY;
 511	key.offset = 0;
 512
 513	btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
 514		struct extent_buffer *leaf = path->nodes[0];
 515
 516		if (found_key.objectid != src_dev->devid)
 517			break;
 518
 519		if (found_key.type != BTRFS_DEV_EXTENT_KEY)
 520			break;
 521
 522		if (found_key.offset < key.offset)
 523			break;
 524
 525		dev_extent = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_extent);
 526
 527		chunk_offset = btrfs_dev_extent_chunk_offset(leaf, dev_extent);
 528
 529		cache = btrfs_lookup_block_group(fs_info, chunk_offset);
 530		if (!cache)
 531			continue;
 532
 533		set_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
 534		btrfs_put_block_group(cache);
 535	}
 536	if (iter_ret < 0)
 537		ret = iter_ret;
 538
 539	btrfs_free_path(path);
 540unlock:
 541	mutex_unlock(&fs_info->chunk_mutex);
 542
 543	return ret;
 544}
 545
 546bool btrfs_finish_block_group_to_copy(struct btrfs_device *srcdev,
 547				      struct btrfs_block_group *cache,
 548				      u64 physical)
 549{
 550	struct btrfs_fs_info *fs_info = cache->fs_info;
 551	struct btrfs_chunk_map *map;
 552	u64 chunk_offset = cache->start;
 553	int num_extents, cur_extent;
 554	int i;
 555
 556	/* Do not use "to_copy" on non zoned filesystem for now */
 557	if (!btrfs_is_zoned(fs_info))
 558		return true;
 559
 560	spin_lock(&cache->lock);
 561	if (test_bit(BLOCK_GROUP_FLAG_REMOVED, &cache->runtime_flags)) {
 562		spin_unlock(&cache->lock);
 563		return true;
 564	}
 565	spin_unlock(&cache->lock);
 566
 567	map = btrfs_get_chunk_map(fs_info, chunk_offset, 1);
 568	ASSERT(!IS_ERR(map));
 569
 570	num_extents = 0;
 571	cur_extent = 0;
 572	for (i = 0; i < map->num_stripes; i++) {
 573		/* We have more device extent to copy */
 574		if (srcdev != map->stripes[i].dev)
 575			continue;
 576
 577		num_extents++;
 578		if (physical == map->stripes[i].physical)
 579			cur_extent = i;
 580	}
 581
 582	btrfs_free_chunk_map(map);
 583
 584	if (num_extents > 1 && cur_extent < num_extents - 1) {
 585		/*
 586		 * Has more stripes on this device. Keep this block group
 587		 * readonly until we finish all the stripes.
 588		 */
 589		return false;
 590	}
 591
 592	/* Last stripe on this device */
 593	clear_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
 594
 595	return true;
 596}
 597
 598static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 599		const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
 600		int read_src)
 601{
 602	struct btrfs_root *root = fs_info->dev_root;
 603	struct btrfs_trans_handle *trans;
 604	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 605	int ret;
 606	struct btrfs_device *tgt_device = NULL;
 607	struct btrfs_device *src_device = NULL;
 608
 609	src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,
 610						  srcdev_name);
 611	if (IS_ERR(src_device))
 612		return PTR_ERR(src_device);
 613
 614	if (btrfs_pinned_by_swapfile(fs_info, src_device)) {
 615		btrfs_warn_in_rcu(fs_info,
 616	  "cannot replace device %s (devid %llu) due to active swapfile",
 617			btrfs_dev_name(src_device), src_device->devid);
 618		return -ETXTBSY;
 619	}
 620
 621	/*
 622	 * Here we commit the transaction to make sure commit_total_bytes
 623	 * of all the devices are updated.
 624	 */
 625	trans = btrfs_attach_transaction(root);
 626	if (!IS_ERR(trans)) {
 627		ret = btrfs_commit_transaction(trans);
 628		if (ret)
 629			return ret;
 630	} else if (PTR_ERR(trans) != -ENOENT) {
 631		return PTR_ERR(trans);
 632	}
 633
 634	ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
 635					    src_device, &tgt_device);
 636	if (ret)
 637		return ret;
 638
 639	ret = mark_block_group_to_copy(fs_info, src_device);
 640	if (ret)
 641		return ret;
 642
 643	down_write(&dev_replace->rwsem);
 644	switch (dev_replace->replace_state) {
 645	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 646	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 647	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 648		break;
 649	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 650	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 651		ASSERT(0);
 652		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 653		up_write(&dev_replace->rwsem);
 654		goto leave;
 655	}
 656
 657	dev_replace->cont_reading_from_srcdev_mode = read_src;
 658	dev_replace->srcdev = src_device;
 659	dev_replace->tgtdev = tgt_device;
 660
 661	btrfs_info_in_rcu(fs_info,
 662		      "dev_replace from %s (devid %llu) to %s started",
 663		      btrfs_dev_name(src_device),
 664		      src_device->devid,
 665		      btrfs_dev_name(tgt_device));
 666
 667	/*
 668	 * from now on, the writes to the srcdev are all duplicated to
 669	 * go to the tgtdev as well (refer to btrfs_map_block()).
 670	 */
 671	dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
 672	dev_replace->time_started = ktime_get_real_seconds();
 673	dev_replace->cursor_left = 0;
 674	dev_replace->committed_cursor_left = 0;
 675	dev_replace->cursor_left_last_write_of_item = 0;
 676	dev_replace->cursor_right = 0;
 677	dev_replace->is_valid = 1;
 678	dev_replace->item_needs_writeback = 1;
 679	atomic64_set(&dev_replace->num_write_errors, 0);
 680	atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
 681	up_write(&dev_replace->rwsem);
 682
 683	ret = btrfs_sysfs_add_device(tgt_device);
 684	if (ret)
 685		btrfs_err(fs_info, "kobj add dev failed %d", ret);
 686
 687	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 688
 689	/*
 690	 * Commit dev_replace state and reserve 1 item for it.
 691	 * This is crucial to ensure we won't miss copying extents for new block
 692	 * groups that are allocated after we started the device replace, and
 693	 * must be done after setting up the device replace state.
 694	 */
 695	trans = btrfs_start_transaction(root, 1);
 696	if (IS_ERR(trans)) {
 697		ret = PTR_ERR(trans);
 698		down_write(&dev_replace->rwsem);
 699		dev_replace->replace_state =
 700			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
 701		dev_replace->srcdev = NULL;
 702		dev_replace->tgtdev = NULL;
 703		up_write(&dev_replace->rwsem);
 704		goto leave;
 705	}
 706
 707	ret = btrfs_commit_transaction(trans);
 708	WARN_ON(ret);
 709
 710	/* the disk copy procedure reuses the scrub code */
 711	ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
 712			      btrfs_device_get_total_bytes(src_device),
 713			      &dev_replace->scrub_progress, 0, 1);
 714
 715	ret = btrfs_dev_replace_finishing(fs_info, ret);
 716	if (ret == -EINPROGRESS)
 717		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
 718
 719	return ret;
 720
 721leave:
 722	btrfs_destroy_dev_replace_tgtdev(tgt_device);
 723	return ret;
 724}
 725
 726static int btrfs_check_replace_dev_names(struct btrfs_ioctl_dev_replace_args *args)
 727{
 728	if (args->start.srcdevid == 0) {
 729		if (memchr(args->start.srcdev_name, 0,
 730			   sizeof(args->start.srcdev_name)) == NULL)
 731			return -ENAMETOOLONG;
 732	} else {
 733		args->start.srcdev_name[0] = 0;
 734	}
 735
 736	if (memchr(args->start.tgtdev_name, 0,
 737		   sizeof(args->start.tgtdev_name)) == NULL)
 738	    return -ENAMETOOLONG;
 739
 740	return 0;
 741}
 742
 743int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 744			    struct btrfs_ioctl_dev_replace_args *args)
 745{
 746	int ret;
 747
 748	switch (args->start.cont_reading_from_srcdev_mode) {
 749	case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
 750	case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
 751		break;
 752	default:
 753		return -EINVAL;
 754	}
 755	ret = btrfs_check_replace_dev_names(args);
 756	if (ret < 0)
 757		return ret;
 
 758
 759	ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
 760					args->start.srcdevid,
 761					args->start.srcdev_name,
 762					args->start.cont_reading_from_srcdev_mode);
 763	args->result = ret;
 764	/* don't warn if EINPROGRESS, someone else might be running scrub */
 765	if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS ||
 766	    ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR)
 767		return 0;
 768
 769	return ret;
 770}
 771
 772/*
 773 * blocked until all in-flight bios operations are finished.
 774 */
 775static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
 776{
 777	set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 778	wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
 779		   &fs_info->dev_replace.bio_counter));
 780}
 781
 782/*
 783 * we have removed target device, it is safe to allow new bios request.
 784 */
 785static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
 786{
 787	clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
 788	wake_up(&fs_info->dev_replace.replace_wait);
 789}
 790
 791/*
 792 * When finishing the device replace, before swapping the source device with the
 793 * target device we must update the chunk allocation state in the target device,
 794 * as it is empty because replace works by directly copying the chunks and not
 795 * through the normal chunk allocation path.
 796 */
 797static int btrfs_set_target_alloc_state(struct btrfs_device *srcdev,
 798					struct btrfs_device *tgtdev)
 799{
 800	struct extent_state *cached_state = NULL;
 801	u64 start = 0;
 802	u64 found_start;
 803	u64 found_end;
 804	int ret = 0;
 805
 806	lockdep_assert_held(&srcdev->fs_info->chunk_mutex);
 807
 808	while (find_first_extent_bit(&srcdev->alloc_state, start,
 809				     &found_start, &found_end,
 810				     CHUNK_ALLOCATED, &cached_state)) {
 811		ret = set_extent_bit(&tgtdev->alloc_state, found_start,
 812				     found_end, CHUNK_ALLOCATED, NULL);
 813		if (ret)
 814			break;
 815		start = found_end + 1;
 816	}
 817
 818	free_extent_state(cached_state);
 819	return ret;
 820}
 821
 822static void btrfs_dev_replace_update_device_in_mapping_tree(
 823						struct btrfs_fs_info *fs_info,
 824						struct btrfs_device *srcdev,
 825						struct btrfs_device *tgtdev)
 826{
 827	u64 start = 0;
 828	int i;
 829
 830	write_lock(&fs_info->mapping_tree_lock);
 831	do {
 832		struct btrfs_chunk_map *map;
 833
 834		map = btrfs_find_chunk_map_nolock(fs_info, start, U64_MAX);
 835		if (!map)
 836			break;
 837		for (i = 0; i < map->num_stripes; i++)
 838			if (srcdev == map->stripes[i].dev)
 839				map->stripes[i].dev = tgtdev;
 840		start = map->start + map->chunk_len;
 841		btrfs_free_chunk_map(map);
 842	} while (start);
 843	write_unlock(&fs_info->mapping_tree_lock);
 844}
 845
 846static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 847				       int scrub_ret)
 848{
 849	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 850	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 851	struct btrfs_device *tgt_device;
 852	struct btrfs_device *src_device;
 853	struct btrfs_root *root = fs_info->tree_root;
 854	u8 uuid_tmp[BTRFS_UUID_SIZE];
 855	struct btrfs_trans_handle *trans;
 856	int ret = 0;
 857
 858	/* don't allow cancel or unmount to disturb the finishing procedure */
 859	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 860
 861	down_read(&dev_replace->rwsem);
 862	/* was the operation canceled, or is it finished? */
 863	if (dev_replace->replace_state !=
 864	    BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
 865		up_read(&dev_replace->rwsem);
 866		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 867		return 0;
 868	}
 869
 870	tgt_device = dev_replace->tgtdev;
 871	src_device = dev_replace->srcdev;
 872	up_read(&dev_replace->rwsem);
 873
 874	/*
 875	 * flush all outstanding I/O and inode extent mappings before the
 876	 * copy operation is declared as being finished
 877	 */
 878	ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
 879	if (ret) {
 880		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 881		return ret;
 882	}
 883	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 884
 885	/*
 886	 * We have to use this loop approach because at this point src_device
 887	 * has to be available for transaction commit to complete, yet new
 888	 * chunks shouldn't be allocated on the device.
 889	 */
 890	while (1) {
 891		trans = btrfs_start_transaction(root, 0);
 892		if (IS_ERR(trans)) {
 893			mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 894			return PTR_ERR(trans);
 895		}
 896		ret = btrfs_commit_transaction(trans);
 897		WARN_ON(ret);
 898
 899		/* Prevent write_all_supers() during the finishing procedure */
 900		mutex_lock(&fs_devices->device_list_mutex);
 901		/* Prevent new chunks being allocated on the source device */
 902		mutex_lock(&fs_info->chunk_mutex);
 903
 904		if (!list_empty(&src_device->post_commit_list)) {
 905			mutex_unlock(&fs_devices->device_list_mutex);
 906			mutex_unlock(&fs_info->chunk_mutex);
 907		} else {
 908			break;
 909		}
 910	}
 911
 912	down_write(&dev_replace->rwsem);
 913	dev_replace->replace_state =
 914		scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 915			  : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
 916	dev_replace->tgtdev = NULL;
 917	dev_replace->srcdev = NULL;
 918	dev_replace->time_stopped = ktime_get_real_seconds();
 919	dev_replace->item_needs_writeback = 1;
 920
 921	/*
 922	 * Update allocation state in the new device and replace the old device
 923	 * with the new one in the mapping tree.
 924	 */
 925	if (!scrub_ret) {
 926		scrub_ret = btrfs_set_target_alloc_state(src_device, tgt_device);
 927		if (scrub_ret)
 928			goto error;
 929		btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
 930								src_device,
 931								tgt_device);
 932	} else {
 933		if (scrub_ret != -ECANCELED)
 934			btrfs_err_in_rcu(fs_info,
 935				 "btrfs_scrub_dev(%s, %llu, %s) failed %d",
 936				 btrfs_dev_name(src_device),
 937				 src_device->devid,
 938				 btrfs_dev_name(tgt_device), scrub_ret);
 939error:
 940		up_write(&dev_replace->rwsem);
 941		mutex_unlock(&fs_info->chunk_mutex);
 942		mutex_unlock(&fs_devices->device_list_mutex);
 943		btrfs_rm_dev_replace_blocked(fs_info);
 944		if (tgt_device)
 945			btrfs_destroy_dev_replace_tgtdev(tgt_device);
 946		btrfs_rm_dev_replace_unblocked(fs_info);
 947		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 948
 949		return scrub_ret;
 950	}
 951
 952	btrfs_info_in_rcu(fs_info,
 953			  "dev_replace from %s (devid %llu) to %s finished",
 954			  btrfs_dev_name(src_device),
 955			  src_device->devid,
 956			  btrfs_dev_name(tgt_device));
 957	clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 958	tgt_device->devid = src_device->devid;
 959	src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 960	memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
 961	memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
 962	memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
 963	btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
 964	btrfs_device_set_disk_total_bytes(tgt_device,
 965					  src_device->disk_total_bytes);
 966	btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
 967	tgt_device->commit_bytes_used = src_device->bytes_used;
 968
 969	btrfs_assign_next_active_device(src_device, tgt_device);
 970
 971	list_add(&tgt_device->dev_alloc_list, &fs_devices->alloc_list);
 972	fs_devices->rw_devices++;
 973
 974	up_write(&dev_replace->rwsem);
 975	btrfs_rm_dev_replace_blocked(fs_info);
 976
 977	btrfs_rm_dev_replace_remove_srcdev(src_device);
 978
 979	btrfs_rm_dev_replace_unblocked(fs_info);
 980
 981	/*
 982	 * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
 983	 * update on-disk dev stats value during commit transaction
 984	 */
 985	atomic_inc(&tgt_device->dev_stats_ccnt);
 986
 987	/*
 988	 * this is again a consistent state where no dev_replace procedure
 989	 * is running, the target device is part of the filesystem, the
 990	 * source device is not part of the filesystem anymore and its 1st
 991	 * superblock is scratched out so that it is no longer marked to
 992	 * belong to this filesystem.
 993	 */
 994	mutex_unlock(&fs_info->chunk_mutex);
 995	mutex_unlock(&fs_devices->device_list_mutex);
 996
 997	/* replace the sysfs entry */
 998	btrfs_sysfs_remove_device(src_device);
 999	btrfs_sysfs_update_devid(tgt_device);
1000	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &src_device->dev_state))
1001		btrfs_scratch_superblocks(fs_info, src_device);
 
1002
1003	/* write back the superblocks */
1004	trans = btrfs_start_transaction(root, 0);
1005	if (!IS_ERR(trans))
1006		btrfs_commit_transaction(trans);
1007
1008	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1009
1010	btrfs_rm_dev_replace_free_srcdev(src_device);
1011
1012	return 0;
1013}
1014
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1015/*
1016 * Read progress of device replace status according to the state and last
1017 * stored position. The value format is the same as for
1018 * btrfs_dev_replace::progress_1000
1019 */
1020static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
1021{
1022	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1023	u64 ret = 0;
1024
1025	switch (dev_replace->replace_state) {
1026	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1027	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1028		ret = 0;
1029		break;
1030	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1031		ret = 1000;
1032		break;
1033	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1034	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1035		ret = div64_u64(dev_replace->cursor_left,
1036				div_u64(btrfs_device_get_total_bytes(
1037						dev_replace->srcdev), 1000));
1038		break;
1039	}
1040
1041	return ret;
1042}
1043
1044void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
1045			      struct btrfs_ioctl_dev_replace_args *args)
1046{
1047	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1048
1049	down_read(&dev_replace->rwsem);
1050	/* even if !dev_replace_is_valid, the values are good enough for
1051	 * the replace_status ioctl */
1052	args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1053	args->status.replace_state = dev_replace->replace_state;
1054	args->status.time_started = dev_replace->time_started;
1055	args->status.time_stopped = dev_replace->time_stopped;
1056	args->status.num_write_errors =
1057		atomic64_read(&dev_replace->num_write_errors);
1058	args->status.num_uncorrectable_read_errors =
1059		atomic64_read(&dev_replace->num_uncorrectable_read_errors);
1060	args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
1061	up_read(&dev_replace->rwsem);
1062}
1063
1064int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
1065{
1066	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1067	struct btrfs_device *tgt_device = NULL;
1068	struct btrfs_device *src_device = NULL;
1069	struct btrfs_trans_handle *trans;
1070	struct btrfs_root *root = fs_info->tree_root;
1071	int result;
1072	int ret;
1073
1074	if (sb_rdonly(fs_info->sb))
1075		return -EROFS;
1076
1077	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
1078	down_write(&dev_replace->rwsem);
1079	switch (dev_replace->replace_state) {
1080	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1081	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1082	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1083		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
1084		up_write(&dev_replace->rwsem);
1085		break;
1086	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1087		tgt_device = dev_replace->tgtdev;
1088		src_device = dev_replace->srcdev;
1089		up_write(&dev_replace->rwsem);
1090		ret = btrfs_scrub_cancel(fs_info);
1091		if (ret < 0) {
1092			result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
1093		} else {
1094			result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1095			/*
1096			 * btrfs_dev_replace_finishing() will handle the
1097			 * cleanup part
1098			 */
1099			btrfs_info_in_rcu(fs_info,
1100				"dev_replace from %s (devid %llu) to %s canceled",
1101				btrfs_dev_name(src_device), src_device->devid,
1102				btrfs_dev_name(tgt_device));
1103		}
1104		break;
1105	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1106		/*
1107		 * Scrub doing the replace isn't running so we need to do the
1108		 * cleanup step of btrfs_dev_replace_finishing() here
1109		 */
1110		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1111		tgt_device = dev_replace->tgtdev;
1112		src_device = dev_replace->srcdev;
1113		dev_replace->tgtdev = NULL;
1114		dev_replace->srcdev = NULL;
1115		dev_replace->replace_state =
1116				BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
1117		dev_replace->time_stopped = ktime_get_real_seconds();
1118		dev_replace->item_needs_writeback = 1;
1119
1120		up_write(&dev_replace->rwsem);
1121
1122		/* Scrub for replace must not be running in suspended state */
1123		btrfs_scrub_cancel(fs_info);
 
1124
1125		trans = btrfs_start_transaction(root, 0);
1126		if (IS_ERR(trans)) {
1127			mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1128			return PTR_ERR(trans);
1129		}
1130		ret = btrfs_commit_transaction(trans);
1131		WARN_ON(ret);
1132
1133		btrfs_info_in_rcu(fs_info,
1134		"suspended dev_replace from %s (devid %llu) to %s canceled",
1135			btrfs_dev_name(src_device), src_device->devid,
1136			btrfs_dev_name(tgt_device));
1137
1138		if (tgt_device)
1139			btrfs_destroy_dev_replace_tgtdev(tgt_device);
1140		break;
1141	default:
1142		up_write(&dev_replace->rwsem);
1143		result = -EINVAL;
1144	}
1145
1146	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1147	return result;
1148}
1149
1150void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
1151{
1152	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1153
1154	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
1155	down_write(&dev_replace->rwsem);
1156
1157	switch (dev_replace->replace_state) {
1158	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1159	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1160	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1161	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1162		break;
1163	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1164		dev_replace->replace_state =
1165			BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1166		dev_replace->time_stopped = ktime_get_real_seconds();
1167		dev_replace->item_needs_writeback = 1;
1168		btrfs_info(fs_info, "suspending dev_replace for unmount");
1169		break;
1170	}
1171
1172	up_write(&dev_replace->rwsem);
1173	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1174}
1175
1176/* resume dev_replace procedure that was interrupted by unmount */
1177int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
1178{
1179	struct task_struct *task;
1180	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1181
1182	down_write(&dev_replace->rwsem);
1183
1184	switch (dev_replace->replace_state) {
1185	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1186	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1187	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1188		up_write(&dev_replace->rwsem);
1189		return 0;
1190	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1191		break;
1192	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1193		dev_replace->replace_state =
1194			BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
1195		break;
1196	}
1197	if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
1198		btrfs_info(fs_info,
1199			   "cannot continue dev_replace, tgtdev is missing");
1200		btrfs_info(fs_info,
1201			   "you may cancel the operation after 'mount -o degraded'");
1202		dev_replace->replace_state =
1203					BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1204		up_write(&dev_replace->rwsem);
1205		return 0;
1206	}
1207	up_write(&dev_replace->rwsem);
1208
1209	/*
1210	 * This could collide with a paused balance, but the exclusive op logic
1211	 * should never allow both to start and pause. We don't want to allow
1212	 * dev-replace to start anyway.
1213	 */
1214	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
1215		down_write(&dev_replace->rwsem);
1216		dev_replace->replace_state =
1217					BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1218		up_write(&dev_replace->rwsem);
1219		btrfs_info(fs_info,
1220		"cannot resume dev-replace, other exclusive operation running");
1221		return 0;
1222	}
1223
1224	task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
1225	return PTR_ERR_OR_ZERO(task);
1226}
1227
1228static int btrfs_dev_replace_kthread(void *data)
1229{
1230	struct btrfs_fs_info *fs_info = data;
1231	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1232	u64 progress;
1233	int ret;
1234
1235	progress = btrfs_dev_replace_progress(fs_info);
1236	progress = div_u64(progress, 10);
1237	btrfs_info_in_rcu(fs_info,
1238		"continuing dev_replace from %s (devid %llu) to target %s @%u%%",
1239		btrfs_dev_name(dev_replace->srcdev),
1240		dev_replace->srcdev->devid,
1241		btrfs_dev_name(dev_replace->tgtdev),
1242		(unsigned int)progress);
1243
1244	ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
1245			      dev_replace->committed_cursor_left,
1246			      btrfs_device_get_total_bytes(dev_replace->srcdev),
1247			      &dev_replace->scrub_progress, 0, 1);
1248	ret = btrfs_dev_replace_finishing(fs_info, ret);
1249	WARN_ON(ret && ret != -ECANCELED);
1250
1251	btrfs_exclop_finish(fs_info);
1252	return 0;
1253}
1254
1255int __pure btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
1256{
1257	if (!dev_replace->is_valid)
1258		return 0;
1259
1260	switch (dev_replace->replace_state) {
1261	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1262	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1263	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1264		return 0;
1265	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1266	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1267		/*
1268		 * return true even if tgtdev is missing (this is
1269		 * something that can happen if the dev_replace
1270		 * procedure is suspended by an umount and then
1271		 * the tgtdev is missing (or "btrfs dev scan") was
1272		 * not called and the filesystem is remounted
1273		 * in degraded state. This does not stop the
1274		 * dev_replace procedure. It needs to be canceled
1275		 * manually if the cancellation is wanted.
1276		 */
1277		break;
1278	}
1279	return 1;
 
 
 
 
 
1280}
1281
1282void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1283{
1284	percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1285	cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1286}
1287
1288void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1289{
1290	while (1) {
1291		percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1292		if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1293				     &fs_info->fs_state)))
1294			break;
1295
1296		btrfs_bio_counter_dec(fs_info);
1297		wait_event(fs_info->dev_replace.replace_wait,
1298			   !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1299				     &fs_info->fs_state));
1300	}
1301}