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 "extent_map.h"
15 #include "disk-io.h"
16 #include "transaction.h"
17 #include "print-tree.h"
18 #include "volumes.h"
19 #include "async-thread.h"
20 #include "check-integrity.h"
21 #include "dev-replace.h"
22 #include "sysfs.h"
23 #include "zoned.h"
24 #include "block-group.h"
25 #include "fs.h"
26 #include "accessors.h"
27 #include "scrub.h"
28 
29 /*
30  * Device replace overview
31  *
32  * [Objective]
33  * To copy all extents (both new and on-disk) from source device to target
34  * device, while still keeping the filesystem read-write.
35  *
36  * [Method]
37  * There are two main methods involved:
38  *
39  * - Write duplication
40  *
41  *   All new writes will be written to both target and source devices, so even
42  *   if replace gets canceled, sources device still contains up-to-date data.
43  *
44  *   Location:		handle_ops_on_dev_replace() from btrfs_map_block()
45  *   Start:		btrfs_dev_replace_start()
46  *   End:		btrfs_dev_replace_finishing()
47  *   Content:		Latest data/metadata
48  *
49  * - Copy existing extents
50  *
51  *   This happens by re-using scrub facility, as scrub also iterates through
52  *   existing extents from commit root.
53  *
54  *   Location:		scrub_write_block_to_dev_replace() from
55  *   			scrub_block_complete()
56  *   Content:		Data/meta from commit root.
57  *
58  * Due to the content difference, we need to avoid nocow write when dev-replace
59  * is happening.  This is done by marking the block group read-only and waiting
60  * for NOCOW writes.
61  *
62  * After replace is done, the finishing part is done by swapping the target and
63  * source devices.
64  *
65  *   Location:		btrfs_dev_replace_update_device_in_mapping_tree() from
66  *   			btrfs_dev_replace_finishing()
67  */
68 
69 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
70 				       int scrub_ret);
71 static int btrfs_dev_replace_kthread(void *data);
72 
btrfs_init_dev_replace(struct btrfs_fs_info * fs_info)73 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
74 {
75 	struct btrfs_dev_lookup_args args = { .devid = BTRFS_DEV_REPLACE_DEVID };
76 	struct btrfs_key key;
77 	struct btrfs_root *dev_root = fs_info->dev_root;
78 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
79 	struct extent_buffer *eb;
80 	int slot;
81 	int ret = 0;
82 	struct btrfs_path *path = NULL;
83 	int item_size;
84 	struct btrfs_dev_replace_item *ptr;
85 	u64 src_devid;
86 
87 	if (!dev_root)
88 		return 0;
89 
90 	path = btrfs_alloc_path();
91 	if (!path) {
92 		ret = -ENOMEM;
93 		goto out;
94 	}
95 
96 	key.objectid = 0;
97 	key.type = BTRFS_DEV_REPLACE_KEY;
98 	key.offset = 0;
99 	ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
100 	if (ret) {
101 no_valid_dev_replace_entry_found:
102 		/*
103 		 * We don't have a replace item or it's corrupted.  If there is
104 		 * a replace target, fail the mount.
105 		 */
106 		if (btrfs_find_device(fs_info->fs_devices, &args)) {
107 			btrfs_err(fs_info,
108 			"found replace target device without a valid replace item");
109 			ret = -EUCLEAN;
110 			goto out;
111 		}
112 		ret = 0;
113 		dev_replace->replace_state =
114 			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
115 		dev_replace->cont_reading_from_srcdev_mode =
116 		    BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
117 		dev_replace->time_started = 0;
118 		dev_replace->time_stopped = 0;
119 		atomic64_set(&dev_replace->num_write_errors, 0);
120 		atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
121 		dev_replace->cursor_left = 0;
122 		dev_replace->committed_cursor_left = 0;
123 		dev_replace->cursor_left_last_write_of_item = 0;
124 		dev_replace->cursor_right = 0;
125 		dev_replace->srcdev = NULL;
126 		dev_replace->tgtdev = NULL;
127 		dev_replace->is_valid = 0;
128 		dev_replace->item_needs_writeback = 0;
129 		goto out;
130 	}
131 	slot = path->slots[0];
132 	eb = path->nodes[0];
133 	item_size = btrfs_item_size(eb, slot);
134 	ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
135 
136 	if (item_size != sizeof(struct btrfs_dev_replace_item)) {
137 		btrfs_warn(fs_info,
138 			"dev_replace entry found has unexpected size, ignore entry");
139 		goto no_valid_dev_replace_entry_found;
140 	}
141 
142 	src_devid = btrfs_dev_replace_src_devid(eb, ptr);
143 	dev_replace->cont_reading_from_srcdev_mode =
144 		btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
145 	dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
146 	dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
147 	dev_replace->time_stopped =
148 		btrfs_dev_replace_time_stopped(eb, ptr);
149 	atomic64_set(&dev_replace->num_write_errors,
150 		     btrfs_dev_replace_num_write_errors(eb, ptr));
151 	atomic64_set(&dev_replace->num_uncorrectable_read_errors,
152 		     btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
153 	dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
154 	dev_replace->committed_cursor_left = dev_replace->cursor_left;
155 	dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
156 	dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
157 	dev_replace->is_valid = 1;
158 
159 	dev_replace->item_needs_writeback = 0;
160 	switch (dev_replace->replace_state) {
161 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
162 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
163 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
164 		/*
165 		 * We don't have an active replace item but if there is a
166 		 * replace target, fail the mount.
167 		 */
168 		if (btrfs_find_device(fs_info->fs_devices, &args)) {
169 			btrfs_err(fs_info,
170 "replace without active item, run 'device scan --forget' on the target device");
171 			ret = -EUCLEAN;
172 		} else {
173 			dev_replace->srcdev = NULL;
174 			dev_replace->tgtdev = NULL;
175 		}
176 		break;
177 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
178 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
179 		dev_replace->tgtdev = btrfs_find_device(fs_info->fs_devices, &args);
180 		args.devid = src_devid;
181 		dev_replace->srcdev = btrfs_find_device(fs_info->fs_devices, &args);
182 
183 		/*
184 		 * allow 'btrfs dev replace_cancel' if src/tgt device is
185 		 * missing
186 		 */
187 		if (!dev_replace->srcdev &&
188 		    !btrfs_test_opt(fs_info, DEGRADED)) {
189 			ret = -EIO;
190 			btrfs_warn(fs_info,
191 			   "cannot mount because device replace operation is ongoing and");
192 			btrfs_warn(fs_info,
193 			   "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
194 			   src_devid);
195 		}
196 		if (!dev_replace->tgtdev &&
197 		    !btrfs_test_opt(fs_info, DEGRADED)) {
198 			ret = -EIO;
199 			btrfs_warn(fs_info,
200 			   "cannot mount because device replace operation is ongoing and");
201 			btrfs_warn(fs_info,
202 			   "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
203 				BTRFS_DEV_REPLACE_DEVID);
204 		}
205 		if (dev_replace->tgtdev) {
206 			if (dev_replace->srcdev) {
207 				dev_replace->tgtdev->total_bytes =
208 					dev_replace->srcdev->total_bytes;
209 				dev_replace->tgtdev->disk_total_bytes =
210 					dev_replace->srcdev->disk_total_bytes;
211 				dev_replace->tgtdev->commit_total_bytes =
212 					dev_replace->srcdev->commit_total_bytes;
213 				dev_replace->tgtdev->bytes_used =
214 					dev_replace->srcdev->bytes_used;
215 				dev_replace->tgtdev->commit_bytes_used =
216 					dev_replace->srcdev->commit_bytes_used;
217 			}
218 			set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
219 				&dev_replace->tgtdev->dev_state);
220 
221 			WARN_ON(fs_info->fs_devices->rw_devices == 0);
222 			dev_replace->tgtdev->io_width = fs_info->sectorsize;
223 			dev_replace->tgtdev->io_align = fs_info->sectorsize;
224 			dev_replace->tgtdev->sector_size = fs_info->sectorsize;
225 			dev_replace->tgtdev->fs_info = fs_info;
226 			set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
227 				&dev_replace->tgtdev->dev_state);
228 		}
229 		break;
230 	}
231 
232 out:
233 	btrfs_free_path(path);
234 	return ret;
235 }
236 
237 /*
238  * Initialize a new device for device replace target from a given source dev
239  * and path.
240  *
241  * Return 0 and new device in @device_out, otherwise return < 0
242  */
btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info * fs_info,const char * device_path,struct btrfs_device * srcdev,struct btrfs_device ** device_out)243 static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
244 				  const char *device_path,
245 				  struct btrfs_device *srcdev,
246 				  struct btrfs_device **device_out)
247 {
248 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
249 	struct btrfs_device *device;
250 	struct block_device *bdev;
251 	u64 devid = BTRFS_DEV_REPLACE_DEVID;
252 	int ret = 0;
253 
254 	*device_out = NULL;
255 	if (srcdev->fs_devices->seeding) {
256 		btrfs_err(fs_info, "the filesystem is a seed filesystem!");
257 		return -EINVAL;
258 	}
259 
260 	bdev = blkdev_get_by_path(device_path, BLK_OPEN_WRITE,
261 				  fs_info->bdev_holder, NULL);
262 	if (IS_ERR(bdev)) {
263 		btrfs_err(fs_info, "target device %s is invalid!", device_path);
264 		return PTR_ERR(bdev);
265 	}
266 
267 	if (!btrfs_check_device_zone_type(fs_info, bdev)) {
268 		btrfs_err(fs_info,
269 		"dev-replace: zoned type of target device mismatch with filesystem");
270 		ret = -EINVAL;
271 		goto error;
272 	}
273 
274 	sync_blockdev(bdev);
275 
276 	list_for_each_entry(device, &fs_devices->devices, dev_list) {
277 		if (device->bdev == bdev) {
278 			btrfs_err(fs_info,
279 				  "target device is in the filesystem!");
280 			ret = -EEXIST;
281 			goto error;
282 		}
283 	}
284 
285 
286 	if (bdev_nr_bytes(bdev) < btrfs_device_get_total_bytes(srcdev)) {
287 		btrfs_err(fs_info,
288 			  "target device is smaller than source device!");
289 		ret = -EINVAL;
290 		goto error;
291 	}
292 
293 
294 	device = btrfs_alloc_device(NULL, &devid, NULL, device_path);
295 	if (IS_ERR(device)) {
296 		ret = PTR_ERR(device);
297 		goto error;
298 	}
299 
300 	ret = lookup_bdev(device_path, &device->devt);
301 	if (ret)
302 		goto error;
303 
304 	set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
305 	device->generation = 0;
306 	device->io_width = fs_info->sectorsize;
307 	device->io_align = fs_info->sectorsize;
308 	device->sector_size = fs_info->sectorsize;
309 	device->total_bytes = btrfs_device_get_total_bytes(srcdev);
310 	device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
311 	device->bytes_used = btrfs_device_get_bytes_used(srcdev);
312 	device->commit_total_bytes = srcdev->commit_total_bytes;
313 	device->commit_bytes_used = device->bytes_used;
314 	device->fs_info = fs_info;
315 	device->bdev = bdev;
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->holder = fs_info->bdev_holder;
319 	device->dev_stats_valid = 1;
320 	set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
321 	device->fs_devices = fs_devices;
322 
323 	ret = btrfs_get_dev_zone_info(device, false);
324 	if (ret)
325 		goto error;
326 
327 	mutex_lock(&fs_devices->device_list_mutex);
328 	list_add(&device->dev_list, &fs_devices->devices);
329 	fs_devices->num_devices++;
330 	fs_devices->open_devices++;
331 	mutex_unlock(&fs_devices->device_list_mutex);
332 
333 	*device_out = device;
334 	return 0;
335 
336 error:
337 	blkdev_put(bdev, fs_info->bdev_holder);
338 	return ret;
339 }
340 
341 /*
342  * called from commit_transaction. Writes changed device replace state to
343  * disk.
344  */
btrfs_run_dev_replace(struct btrfs_trans_handle * trans)345 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans)
346 {
347 	struct btrfs_fs_info *fs_info = trans->fs_info;
348 	int ret;
349 	struct btrfs_root *dev_root = fs_info->dev_root;
350 	struct btrfs_path *path;
351 	struct btrfs_key key;
352 	struct extent_buffer *eb;
353 	struct btrfs_dev_replace_item *ptr;
354 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
355 
356 	down_read(&dev_replace->rwsem);
357 	if (!dev_replace->is_valid ||
358 	    !dev_replace->item_needs_writeback) {
359 		up_read(&dev_replace->rwsem);
360 		return 0;
361 	}
362 	up_read(&dev_replace->rwsem);
363 
364 	key.objectid = 0;
365 	key.type = BTRFS_DEV_REPLACE_KEY;
366 	key.offset = 0;
367 
368 	path = btrfs_alloc_path();
369 	if (!path) {
370 		ret = -ENOMEM;
371 		goto out;
372 	}
373 	ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
374 	if (ret < 0) {
375 		btrfs_warn(fs_info,
376 			   "error %d while searching for dev_replace item!",
377 			   ret);
378 		goto out;
379 	}
380 
381 	if (ret == 0 &&
382 	    btrfs_item_size(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
383 		/*
384 		 * need to delete old one and insert a new one.
385 		 * Since no attempt is made to recover any old state, if the
386 		 * dev_replace state is 'running', the data on the target
387 		 * drive is lost.
388 		 * It would be possible to recover the state: just make sure
389 		 * that the beginning of the item is never changed and always
390 		 * contains all the essential information. Then read this
391 		 * minimal set of information and use it as a base for the
392 		 * new state.
393 		 */
394 		ret = btrfs_del_item(trans, dev_root, path);
395 		if (ret != 0) {
396 			btrfs_warn(fs_info,
397 				   "delete too small dev_replace item failed %d!",
398 				   ret);
399 			goto out;
400 		}
401 		ret = 1;
402 	}
403 
404 	if (ret == 1) {
405 		/* need to insert a new item */
406 		btrfs_release_path(path);
407 		ret = btrfs_insert_empty_item(trans, dev_root, path,
408 					      &key, sizeof(*ptr));
409 		if (ret < 0) {
410 			btrfs_warn(fs_info,
411 				   "insert dev_replace item failed %d!", ret);
412 			goto out;
413 		}
414 	}
415 
416 	eb = path->nodes[0];
417 	ptr = btrfs_item_ptr(eb, path->slots[0],
418 			     struct btrfs_dev_replace_item);
419 
420 	down_write(&dev_replace->rwsem);
421 	if (dev_replace->srcdev)
422 		btrfs_set_dev_replace_src_devid(eb, ptr,
423 			dev_replace->srcdev->devid);
424 	else
425 		btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
426 	btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
427 		dev_replace->cont_reading_from_srcdev_mode);
428 	btrfs_set_dev_replace_replace_state(eb, ptr,
429 		dev_replace->replace_state);
430 	btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
431 	btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
432 	btrfs_set_dev_replace_num_write_errors(eb, ptr,
433 		atomic64_read(&dev_replace->num_write_errors));
434 	btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
435 		atomic64_read(&dev_replace->num_uncorrectable_read_errors));
436 	dev_replace->cursor_left_last_write_of_item =
437 		dev_replace->cursor_left;
438 	btrfs_set_dev_replace_cursor_left(eb, ptr,
439 		dev_replace->cursor_left_last_write_of_item);
440 	btrfs_set_dev_replace_cursor_right(eb, ptr,
441 		dev_replace->cursor_right);
442 	dev_replace->item_needs_writeback = 0;
443 	up_write(&dev_replace->rwsem);
444 
445 	btrfs_mark_buffer_dirty(trans, eb);
446 
447 out:
448 	btrfs_free_path(path);
449 
450 	return ret;
451 }
452 
mark_block_group_to_copy(struct btrfs_fs_info * fs_info,struct btrfs_device * src_dev)453 static int mark_block_group_to_copy(struct btrfs_fs_info *fs_info,
454 				    struct btrfs_device *src_dev)
455 {
456 	struct btrfs_path *path;
457 	struct btrfs_key key;
458 	struct btrfs_key found_key;
459 	struct btrfs_root *root = fs_info->dev_root;
460 	struct btrfs_dev_extent *dev_extent = NULL;
461 	struct btrfs_block_group *cache;
462 	struct btrfs_trans_handle *trans;
463 	int iter_ret = 0;
464 	int ret = 0;
465 	u64 chunk_offset;
466 
467 	/* Do not use "to_copy" on non zoned filesystem for now */
468 	if (!btrfs_is_zoned(fs_info))
469 		return 0;
470 
471 	mutex_lock(&fs_info->chunk_mutex);
472 
473 	/* Ensure we don't have pending new block group */
474 	spin_lock(&fs_info->trans_lock);
475 	while (fs_info->running_transaction &&
476 	       !list_empty(&fs_info->running_transaction->dev_update_list)) {
477 		spin_unlock(&fs_info->trans_lock);
478 		mutex_unlock(&fs_info->chunk_mutex);
479 		trans = btrfs_attach_transaction(root);
480 		if (IS_ERR(trans)) {
481 			ret = PTR_ERR(trans);
482 			mutex_lock(&fs_info->chunk_mutex);
483 			if (ret == -ENOENT) {
484 				spin_lock(&fs_info->trans_lock);
485 				continue;
486 			} else {
487 				goto unlock;
488 			}
489 		}
490 
491 		ret = btrfs_commit_transaction(trans);
492 		mutex_lock(&fs_info->chunk_mutex);
493 		if (ret)
494 			goto unlock;
495 
496 		spin_lock(&fs_info->trans_lock);
497 	}
498 	spin_unlock(&fs_info->trans_lock);
499 
500 	path = btrfs_alloc_path();
501 	if (!path) {
502 		ret = -ENOMEM;
503 		goto unlock;
504 	}
505 
506 	path->reada = READA_FORWARD;
507 	path->search_commit_root = 1;
508 	path->skip_locking = 1;
509 
510 	key.objectid = src_dev->devid;
511 	key.type = BTRFS_DEV_EXTENT_KEY;
512 	key.offset = 0;
513 
514 	btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
515 		struct extent_buffer *leaf = path->nodes[0];
516 
517 		if (found_key.objectid != src_dev->devid)
518 			break;
519 
520 		if (found_key.type != BTRFS_DEV_EXTENT_KEY)
521 			break;
522 
523 		if (found_key.offset < key.offset)
524 			break;
525 
526 		dev_extent = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_extent);
527 
528 		chunk_offset = btrfs_dev_extent_chunk_offset(leaf, dev_extent);
529 
530 		cache = btrfs_lookup_block_group(fs_info, chunk_offset);
531 		if (!cache)
532 			continue;
533 
534 		set_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
535 		btrfs_put_block_group(cache);
536 	}
537 	if (iter_ret < 0)
538 		ret = iter_ret;
539 
540 	btrfs_free_path(path);
541 unlock:
542 	mutex_unlock(&fs_info->chunk_mutex);
543 
544 	return ret;
545 }
546 
btrfs_finish_block_group_to_copy(struct btrfs_device * srcdev,struct btrfs_block_group * cache,u64 physical)547 bool btrfs_finish_block_group_to_copy(struct btrfs_device *srcdev,
548 				      struct btrfs_block_group *cache,
549 				      u64 physical)
550 {
551 	struct btrfs_fs_info *fs_info = cache->fs_info;
552 	struct extent_map *em;
553 	struct map_lookup *map;
554 	u64 chunk_offset = cache->start;
555 	int num_extents, cur_extent;
556 	int i;
557 
558 	/* Do not use "to_copy" on non zoned filesystem for now */
559 	if (!btrfs_is_zoned(fs_info))
560 		return true;
561 
562 	spin_lock(&cache->lock);
563 	if (test_bit(BLOCK_GROUP_FLAG_REMOVED, &cache->runtime_flags)) {
564 		spin_unlock(&cache->lock);
565 		return true;
566 	}
567 	spin_unlock(&cache->lock);
568 
569 	em = btrfs_get_chunk_map(fs_info, chunk_offset, 1);
570 	ASSERT(!IS_ERR(em));
571 	map = em->map_lookup;
572 
573 	num_extents = 0;
574 	cur_extent = 0;
575 	for (i = 0; i < map->num_stripes; i++) {
576 		/* We have more device extent to copy */
577 		if (srcdev != map->stripes[i].dev)
578 			continue;
579 
580 		num_extents++;
581 		if (physical == map->stripes[i].physical)
582 			cur_extent = i;
583 	}
584 
585 	free_extent_map(em);
586 
587 	if (num_extents > 1 && cur_extent < num_extents - 1) {
588 		/*
589 		 * Has more stripes on this device. Keep this block group
590 		 * readonly until we finish all the stripes.
591 		 */
592 		return false;
593 	}
594 
595 	/* Last stripe on this device */
596 	clear_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
597 
598 	return true;
599 }
600 
btrfs_dev_replace_start(struct btrfs_fs_info * fs_info,const char * tgtdev_name,u64 srcdevid,const char * srcdev_name,int read_src)601 static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
602 		const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
603 		int read_src)
604 {
605 	struct btrfs_root *root = fs_info->dev_root;
606 	struct btrfs_trans_handle *trans;
607 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
608 	int ret;
609 	struct btrfs_device *tgt_device = NULL;
610 	struct btrfs_device *src_device = NULL;
611 
612 	src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,
613 						  srcdev_name);
614 	if (IS_ERR(src_device))
615 		return PTR_ERR(src_device);
616 
617 	if (btrfs_pinned_by_swapfile(fs_info, src_device)) {
618 		btrfs_warn_in_rcu(fs_info,
619 	  "cannot replace device %s (devid %llu) due to active swapfile",
620 			btrfs_dev_name(src_device), src_device->devid);
621 		return -ETXTBSY;
622 	}
623 
624 	/*
625 	 * Here we commit the transaction to make sure commit_total_bytes
626 	 * of all the devices are updated.
627 	 */
628 	trans = btrfs_attach_transaction(root);
629 	if (!IS_ERR(trans)) {
630 		ret = btrfs_commit_transaction(trans);
631 		if (ret)
632 			return ret;
633 	} else if (PTR_ERR(trans) != -ENOENT) {
634 		return PTR_ERR(trans);
635 	}
636 
637 	ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
638 					    src_device, &tgt_device);
639 	if (ret)
640 		return ret;
641 
642 	ret = mark_block_group_to_copy(fs_info, src_device);
643 	if (ret)
644 		return ret;
645 
646 	down_write(&dev_replace->rwsem);
647 	switch (dev_replace->replace_state) {
648 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
649 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
650 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
651 		break;
652 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
653 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
654 		ASSERT(0);
655 		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
656 		up_write(&dev_replace->rwsem);
657 		goto leave;
658 	}
659 
660 	dev_replace->cont_reading_from_srcdev_mode = read_src;
661 	dev_replace->srcdev = src_device;
662 	dev_replace->tgtdev = tgt_device;
663 
664 	btrfs_info_in_rcu(fs_info,
665 		      "dev_replace from %s (devid %llu) to %s started",
666 		      btrfs_dev_name(src_device),
667 		      src_device->devid,
668 		      btrfs_dev_name(tgt_device));
669 
670 	/*
671 	 * from now on, the writes to the srcdev are all duplicated to
672 	 * go to the tgtdev as well (refer to btrfs_map_block()).
673 	 */
674 	dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
675 	dev_replace->time_started = ktime_get_real_seconds();
676 	dev_replace->cursor_left = 0;
677 	dev_replace->committed_cursor_left = 0;
678 	dev_replace->cursor_left_last_write_of_item = 0;
679 	dev_replace->cursor_right = 0;
680 	dev_replace->is_valid = 1;
681 	dev_replace->item_needs_writeback = 1;
682 	atomic64_set(&dev_replace->num_write_errors, 0);
683 	atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
684 	up_write(&dev_replace->rwsem);
685 
686 	ret = btrfs_sysfs_add_device(tgt_device);
687 	if (ret)
688 		btrfs_err(fs_info, "kobj add dev failed %d", ret);
689 
690 	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
691 
692 	/*
693 	 * Commit dev_replace state and reserve 1 item for it.
694 	 * This is crucial to ensure we won't miss copying extents for new block
695 	 * groups that are allocated after we started the device replace, and
696 	 * must be done after setting up the device replace state.
697 	 */
698 	trans = btrfs_start_transaction(root, 1);
699 	if (IS_ERR(trans)) {
700 		ret = PTR_ERR(trans);
701 		down_write(&dev_replace->rwsem);
702 		dev_replace->replace_state =
703 			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
704 		dev_replace->srcdev = NULL;
705 		dev_replace->tgtdev = NULL;
706 		up_write(&dev_replace->rwsem);
707 		goto leave;
708 	}
709 
710 	ret = btrfs_commit_transaction(trans);
711 	WARN_ON(ret);
712 
713 	/* the disk copy procedure reuses the scrub code */
714 	ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
715 			      btrfs_device_get_total_bytes(src_device),
716 			      &dev_replace->scrub_progress, 0, 1);
717 
718 	ret = btrfs_dev_replace_finishing(fs_info, ret);
719 	if (ret == -EINPROGRESS)
720 		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
721 
722 	return ret;
723 
724 leave:
725 	btrfs_destroy_dev_replace_tgtdev(tgt_device);
726 	return ret;
727 }
728 
btrfs_check_replace_dev_names(struct btrfs_ioctl_dev_replace_args * args)729 static int btrfs_check_replace_dev_names(struct btrfs_ioctl_dev_replace_args *args)
730 {
731 	if (args->start.srcdevid == 0) {
732 		if (memchr(args->start.srcdev_name, 0,
733 			   sizeof(args->start.srcdev_name)) == NULL)
734 			return -ENAMETOOLONG;
735 	} else {
736 		args->start.srcdev_name[0] = 0;
737 	}
738 
739 	if (memchr(args->start.tgtdev_name, 0,
740 		   sizeof(args->start.tgtdev_name)) == NULL)
741 	    return -ENAMETOOLONG;
742 
743 	return 0;
744 }
745 
btrfs_dev_replace_by_ioctl(struct btrfs_fs_info * fs_info,struct btrfs_ioctl_dev_replace_args * args)746 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
747 			    struct btrfs_ioctl_dev_replace_args *args)
748 {
749 	int ret;
750 
751 	switch (args->start.cont_reading_from_srcdev_mode) {
752 	case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
753 	case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
754 		break;
755 	default:
756 		return -EINVAL;
757 	}
758 	ret = btrfs_check_replace_dev_names(args);
759 	if (ret < 0)
760 		return ret;
761 
762 	ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
763 					args->start.srcdevid,
764 					args->start.srcdev_name,
765 					args->start.cont_reading_from_srcdev_mode);
766 	args->result = ret;
767 	/* don't warn if EINPROGRESS, someone else might be running scrub */
768 	if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS ||
769 	    ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR)
770 		return 0;
771 
772 	return ret;
773 }
774 
775 /*
776  * blocked until all in-flight bios operations are finished.
777  */
btrfs_rm_dev_replace_blocked(struct btrfs_fs_info * fs_info)778 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
779 {
780 	set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
781 	wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
782 		   &fs_info->dev_replace.bio_counter));
783 }
784 
785 /*
786  * we have removed target device, it is safe to allow new bios request.
787  */
btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info * fs_info)788 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
789 {
790 	clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
791 	wake_up(&fs_info->dev_replace.replace_wait);
792 }
793 
794 /*
795  * When finishing the device replace, before swapping the source device with the
796  * target device we must update the chunk allocation state in the target device,
797  * as it is empty because replace works by directly copying the chunks and not
798  * through the normal chunk allocation path.
799  */
btrfs_set_target_alloc_state(struct btrfs_device * srcdev,struct btrfs_device * tgtdev)800 static int btrfs_set_target_alloc_state(struct btrfs_device *srcdev,
801 					struct btrfs_device *tgtdev)
802 {
803 	struct extent_state *cached_state = NULL;
804 	u64 start = 0;
805 	u64 found_start;
806 	u64 found_end;
807 	int ret = 0;
808 
809 	lockdep_assert_held(&srcdev->fs_info->chunk_mutex);
810 
811 	while (find_first_extent_bit(&srcdev->alloc_state, start,
812 				     &found_start, &found_end,
813 				     CHUNK_ALLOCATED, &cached_state)) {
814 		ret = set_extent_bit(&tgtdev->alloc_state, found_start,
815 				     found_end, CHUNK_ALLOCATED, NULL);
816 		if (ret)
817 			break;
818 		start = found_end + 1;
819 	}
820 
821 	free_extent_state(cached_state);
822 	return ret;
823 }
824 
btrfs_dev_replace_update_device_in_mapping_tree(struct btrfs_fs_info * fs_info,struct btrfs_device * srcdev,struct btrfs_device * tgtdev)825 static void btrfs_dev_replace_update_device_in_mapping_tree(
826 						struct btrfs_fs_info *fs_info,
827 						struct btrfs_device *srcdev,
828 						struct btrfs_device *tgtdev)
829 {
830 	struct extent_map_tree *em_tree = &fs_info->mapping_tree;
831 	struct extent_map *em;
832 	struct map_lookup *map;
833 	u64 start = 0;
834 	int i;
835 
836 	write_lock(&em_tree->lock);
837 	do {
838 		em = lookup_extent_mapping(em_tree, start, (u64)-1);
839 		if (!em)
840 			break;
841 		map = em->map_lookup;
842 		for (i = 0; i < map->num_stripes; i++)
843 			if (srcdev == map->stripes[i].dev)
844 				map->stripes[i].dev = tgtdev;
845 		start = em->start + em->len;
846 		free_extent_map(em);
847 	} while (start);
848 	write_unlock(&em_tree->lock);
849 }
850 
btrfs_dev_replace_finishing(struct btrfs_fs_info * fs_info,int scrub_ret)851 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
852 				       int scrub_ret)
853 {
854 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
855 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
856 	struct btrfs_device *tgt_device;
857 	struct btrfs_device *src_device;
858 	struct btrfs_root *root = fs_info->tree_root;
859 	u8 uuid_tmp[BTRFS_UUID_SIZE];
860 	struct btrfs_trans_handle *trans;
861 	int ret = 0;
862 
863 	/* don't allow cancel or unmount to disturb the finishing procedure */
864 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
865 
866 	down_read(&dev_replace->rwsem);
867 	/* was the operation canceled, or is it finished? */
868 	if (dev_replace->replace_state !=
869 	    BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
870 		up_read(&dev_replace->rwsem);
871 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
872 		return 0;
873 	}
874 
875 	tgt_device = dev_replace->tgtdev;
876 	src_device = dev_replace->srcdev;
877 	up_read(&dev_replace->rwsem);
878 
879 	/*
880 	 * flush all outstanding I/O and inode extent mappings before the
881 	 * copy operation is declared as being finished
882 	 */
883 	ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
884 	if (ret) {
885 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
886 		return ret;
887 	}
888 	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
889 
890 	/*
891 	 * We have to use this loop approach because at this point src_device
892 	 * has to be available for transaction commit to complete, yet new
893 	 * chunks shouldn't be allocated on the device.
894 	 */
895 	while (1) {
896 		trans = btrfs_start_transaction(root, 0);
897 		if (IS_ERR(trans)) {
898 			mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
899 			return PTR_ERR(trans);
900 		}
901 		ret = btrfs_commit_transaction(trans);
902 		WARN_ON(ret);
903 
904 		/* Prevent write_all_supers() during the finishing procedure */
905 		mutex_lock(&fs_devices->device_list_mutex);
906 		/* Prevent new chunks being allocated on the source device */
907 		mutex_lock(&fs_info->chunk_mutex);
908 
909 		if (!list_empty(&src_device->post_commit_list)) {
910 			mutex_unlock(&fs_devices->device_list_mutex);
911 			mutex_unlock(&fs_info->chunk_mutex);
912 		} else {
913 			break;
914 		}
915 	}
916 
917 	down_write(&dev_replace->rwsem);
918 	dev_replace->replace_state =
919 		scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
920 			  : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
921 	dev_replace->tgtdev = NULL;
922 	dev_replace->srcdev = NULL;
923 	dev_replace->time_stopped = ktime_get_real_seconds();
924 	dev_replace->item_needs_writeback = 1;
925 
926 	/*
927 	 * Update allocation state in the new device and replace the old device
928 	 * with the new one in the mapping tree.
929 	 */
930 	if (!scrub_ret) {
931 		scrub_ret = btrfs_set_target_alloc_state(src_device, tgt_device);
932 		if (scrub_ret)
933 			goto error;
934 		btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
935 								src_device,
936 								tgt_device);
937 	} else {
938 		if (scrub_ret != -ECANCELED)
939 			btrfs_err_in_rcu(fs_info,
940 				 "btrfs_scrub_dev(%s, %llu, %s) failed %d",
941 				 btrfs_dev_name(src_device),
942 				 src_device->devid,
943 				 btrfs_dev_name(tgt_device), scrub_ret);
944 error:
945 		up_write(&dev_replace->rwsem);
946 		mutex_unlock(&fs_info->chunk_mutex);
947 		mutex_unlock(&fs_devices->device_list_mutex);
948 		btrfs_rm_dev_replace_blocked(fs_info);
949 		if (tgt_device)
950 			btrfs_destroy_dev_replace_tgtdev(tgt_device);
951 		btrfs_rm_dev_replace_unblocked(fs_info);
952 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
953 
954 		return scrub_ret;
955 	}
956 
957 	btrfs_info_in_rcu(fs_info,
958 			  "dev_replace from %s (devid %llu) to %s finished",
959 			  btrfs_dev_name(src_device),
960 			  src_device->devid,
961 			  btrfs_dev_name(tgt_device));
962 	clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
963 	tgt_device->devid = src_device->devid;
964 	src_device->devid = BTRFS_DEV_REPLACE_DEVID;
965 	memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
966 	memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
967 	memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
968 	btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
969 	btrfs_device_set_disk_total_bytes(tgt_device,
970 					  src_device->disk_total_bytes);
971 	btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
972 	tgt_device->commit_bytes_used = src_device->bytes_used;
973 
974 	btrfs_assign_next_active_device(src_device, tgt_device);
975 
976 	list_add(&tgt_device->dev_alloc_list, &fs_devices->alloc_list);
977 	fs_devices->rw_devices++;
978 
979 	up_write(&dev_replace->rwsem);
980 	btrfs_rm_dev_replace_blocked(fs_info);
981 
982 	btrfs_rm_dev_replace_remove_srcdev(src_device);
983 
984 	btrfs_rm_dev_replace_unblocked(fs_info);
985 
986 	/*
987 	 * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
988 	 * update on-disk dev stats value during commit transaction
989 	 */
990 	atomic_inc(&tgt_device->dev_stats_ccnt);
991 
992 	/*
993 	 * this is again a consistent state where no dev_replace procedure
994 	 * is running, the target device is part of the filesystem, the
995 	 * source device is not part of the filesystem anymore and its 1st
996 	 * superblock is scratched out so that it is no longer marked to
997 	 * belong to this filesystem.
998 	 */
999 	mutex_unlock(&fs_info->chunk_mutex);
1000 	mutex_unlock(&fs_devices->device_list_mutex);
1001 
1002 	/* replace the sysfs entry */
1003 	btrfs_sysfs_remove_device(src_device);
1004 	btrfs_sysfs_update_devid(tgt_device);
1005 	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &src_device->dev_state))
1006 		btrfs_scratch_superblocks(fs_info, src_device->bdev,
1007 					  src_device->name->str);
1008 
1009 	/* write back the superblocks */
1010 	trans = btrfs_start_transaction(root, 0);
1011 	if (!IS_ERR(trans))
1012 		btrfs_commit_transaction(trans);
1013 
1014 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1015 
1016 	btrfs_rm_dev_replace_free_srcdev(src_device);
1017 
1018 	return 0;
1019 }
1020 
1021 /*
1022  * Read progress of device replace status according to the state and last
1023  * stored position. The value format is the same as for
1024  * btrfs_dev_replace::progress_1000
1025  */
btrfs_dev_replace_progress(struct btrfs_fs_info * fs_info)1026 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
1027 {
1028 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1029 	u64 ret = 0;
1030 
1031 	switch (dev_replace->replace_state) {
1032 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1033 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1034 		ret = 0;
1035 		break;
1036 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1037 		ret = 1000;
1038 		break;
1039 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1040 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1041 		ret = div64_u64(dev_replace->cursor_left,
1042 				div_u64(btrfs_device_get_total_bytes(
1043 						dev_replace->srcdev), 1000));
1044 		break;
1045 	}
1046 
1047 	return ret;
1048 }
1049 
btrfs_dev_replace_status(struct btrfs_fs_info * fs_info,struct btrfs_ioctl_dev_replace_args * args)1050 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
1051 			      struct btrfs_ioctl_dev_replace_args *args)
1052 {
1053 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1054 
1055 	down_read(&dev_replace->rwsem);
1056 	/* even if !dev_replace_is_valid, the values are good enough for
1057 	 * the replace_status ioctl */
1058 	args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1059 	args->status.replace_state = dev_replace->replace_state;
1060 	args->status.time_started = dev_replace->time_started;
1061 	args->status.time_stopped = dev_replace->time_stopped;
1062 	args->status.num_write_errors =
1063 		atomic64_read(&dev_replace->num_write_errors);
1064 	args->status.num_uncorrectable_read_errors =
1065 		atomic64_read(&dev_replace->num_uncorrectable_read_errors);
1066 	args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
1067 	up_read(&dev_replace->rwsem);
1068 }
1069 
btrfs_dev_replace_cancel(struct btrfs_fs_info * fs_info)1070 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
1071 {
1072 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1073 	struct btrfs_device *tgt_device = NULL;
1074 	struct btrfs_device *src_device = NULL;
1075 	struct btrfs_trans_handle *trans;
1076 	struct btrfs_root *root = fs_info->tree_root;
1077 	int result;
1078 	int ret;
1079 
1080 	if (sb_rdonly(fs_info->sb))
1081 		return -EROFS;
1082 
1083 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
1084 	down_write(&dev_replace->rwsem);
1085 	switch (dev_replace->replace_state) {
1086 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1087 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1088 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1089 		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
1090 		up_write(&dev_replace->rwsem);
1091 		break;
1092 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1093 		tgt_device = dev_replace->tgtdev;
1094 		src_device = dev_replace->srcdev;
1095 		up_write(&dev_replace->rwsem);
1096 		ret = btrfs_scrub_cancel(fs_info);
1097 		if (ret < 0) {
1098 			result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
1099 		} else {
1100 			result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1101 			/*
1102 			 * btrfs_dev_replace_finishing() will handle the
1103 			 * cleanup part
1104 			 */
1105 			btrfs_info_in_rcu(fs_info,
1106 				"dev_replace from %s (devid %llu) to %s canceled",
1107 				btrfs_dev_name(src_device), src_device->devid,
1108 				btrfs_dev_name(tgt_device));
1109 		}
1110 		break;
1111 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1112 		/*
1113 		 * Scrub doing the replace isn't running so we need to do the
1114 		 * cleanup step of btrfs_dev_replace_finishing() here
1115 		 */
1116 		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
1117 		tgt_device = dev_replace->tgtdev;
1118 		src_device = dev_replace->srcdev;
1119 		dev_replace->tgtdev = NULL;
1120 		dev_replace->srcdev = NULL;
1121 		dev_replace->replace_state =
1122 				BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
1123 		dev_replace->time_stopped = ktime_get_real_seconds();
1124 		dev_replace->item_needs_writeback = 1;
1125 
1126 		up_write(&dev_replace->rwsem);
1127 
1128 		/* Scrub for replace must not be running in suspended state */
1129 		btrfs_scrub_cancel(fs_info);
1130 
1131 		trans = btrfs_start_transaction(root, 0);
1132 		if (IS_ERR(trans)) {
1133 			mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1134 			return PTR_ERR(trans);
1135 		}
1136 		ret = btrfs_commit_transaction(trans);
1137 		WARN_ON(ret);
1138 
1139 		btrfs_info_in_rcu(fs_info,
1140 		"suspended dev_replace from %s (devid %llu) to %s canceled",
1141 			btrfs_dev_name(src_device), src_device->devid,
1142 			btrfs_dev_name(tgt_device));
1143 
1144 		if (tgt_device)
1145 			btrfs_destroy_dev_replace_tgtdev(tgt_device);
1146 		break;
1147 	default:
1148 		up_write(&dev_replace->rwsem);
1149 		result = -EINVAL;
1150 	}
1151 
1152 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1153 	return result;
1154 }
1155 
btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info * fs_info)1156 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
1157 {
1158 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1159 
1160 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
1161 	down_write(&dev_replace->rwsem);
1162 
1163 	switch (dev_replace->replace_state) {
1164 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1165 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1166 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1167 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1168 		break;
1169 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1170 		dev_replace->replace_state =
1171 			BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1172 		dev_replace->time_stopped = ktime_get_real_seconds();
1173 		dev_replace->item_needs_writeback = 1;
1174 		btrfs_info(fs_info, "suspending dev_replace for unmount");
1175 		break;
1176 	}
1177 
1178 	up_write(&dev_replace->rwsem);
1179 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
1180 }
1181 
1182 /* resume dev_replace procedure that was interrupted by unmount */
btrfs_resume_dev_replace_async(struct btrfs_fs_info * fs_info)1183 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
1184 {
1185 	struct task_struct *task;
1186 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1187 
1188 	down_write(&dev_replace->rwsem);
1189 
1190 	switch (dev_replace->replace_state) {
1191 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1192 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1193 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1194 		up_write(&dev_replace->rwsem);
1195 		return 0;
1196 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1197 		break;
1198 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1199 		dev_replace->replace_state =
1200 			BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
1201 		break;
1202 	}
1203 	if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
1204 		btrfs_info(fs_info,
1205 			   "cannot continue dev_replace, tgtdev is missing");
1206 		btrfs_info(fs_info,
1207 			   "you may cancel the operation after 'mount -o degraded'");
1208 		dev_replace->replace_state =
1209 					BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1210 		up_write(&dev_replace->rwsem);
1211 		return 0;
1212 	}
1213 	up_write(&dev_replace->rwsem);
1214 
1215 	/*
1216 	 * This could collide with a paused balance, but the exclusive op logic
1217 	 * should never allow both to start and pause. We don't want to allow
1218 	 * dev-replace to start anyway.
1219 	 */
1220 	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
1221 		down_write(&dev_replace->rwsem);
1222 		dev_replace->replace_state =
1223 					BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
1224 		up_write(&dev_replace->rwsem);
1225 		btrfs_info(fs_info,
1226 		"cannot resume dev-replace, other exclusive operation running");
1227 		return 0;
1228 	}
1229 
1230 	task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
1231 	return PTR_ERR_OR_ZERO(task);
1232 }
1233 
btrfs_dev_replace_kthread(void * data)1234 static int btrfs_dev_replace_kthread(void *data)
1235 {
1236 	struct btrfs_fs_info *fs_info = data;
1237 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1238 	u64 progress;
1239 	int ret;
1240 
1241 	progress = btrfs_dev_replace_progress(fs_info);
1242 	progress = div_u64(progress, 10);
1243 	btrfs_info_in_rcu(fs_info,
1244 		"continuing dev_replace from %s (devid %llu) to target %s @%u%%",
1245 		btrfs_dev_name(dev_replace->srcdev),
1246 		dev_replace->srcdev->devid,
1247 		btrfs_dev_name(dev_replace->tgtdev),
1248 		(unsigned int)progress);
1249 
1250 	ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
1251 			      dev_replace->committed_cursor_left,
1252 			      btrfs_device_get_total_bytes(dev_replace->srcdev),
1253 			      &dev_replace->scrub_progress, 0, 1);
1254 	ret = btrfs_dev_replace_finishing(fs_info, ret);
1255 	WARN_ON(ret && ret != -ECANCELED);
1256 
1257 	btrfs_exclop_finish(fs_info);
1258 	return 0;
1259 }
1260 
btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace * dev_replace)1261 int __pure btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
1262 {
1263 	if (!dev_replace->is_valid)
1264 		return 0;
1265 
1266 	switch (dev_replace->replace_state) {
1267 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
1268 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
1269 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
1270 		return 0;
1271 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
1272 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
1273 		/*
1274 		 * return true even if tgtdev is missing (this is
1275 		 * something that can happen if the dev_replace
1276 		 * procedure is suspended by an umount and then
1277 		 * the tgtdev is missing (or "btrfs dev scan") was
1278 		 * not called and the filesystem is remounted
1279 		 * in degraded state. This does not stop the
1280 		 * dev_replace procedure. It needs to be canceled
1281 		 * manually if the cancellation is wanted.
1282 		 */
1283 		break;
1284 	}
1285 	return 1;
1286 }
1287 
btrfs_bio_counter_sub(struct btrfs_fs_info * fs_info,s64 amount)1288 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1289 {
1290 	percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1291 	cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1292 }
1293 
btrfs_bio_counter_inc_blocked(struct btrfs_fs_info * fs_info)1294 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1295 {
1296 	while (1) {
1297 		percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1298 		if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1299 				     &fs_info->fs_state)))
1300 			break;
1301 
1302 		btrfs_bio_counter_dec(fs_info);
1303 		wait_event(fs_info->dev_replace.replace_wait,
1304 			   !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1305 				     &fs_info->fs_state));
1306 	}
1307 }
1308