xref: /openbmc/linux/fs/btrfs/dev-replace.c (revision 92a2c6b2)
1 /*
2  * Copyright (C) STRATO AG 2012.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18 #include <linux/sched.h>
19 #include <linux/bio.h>
20 #include <linux/slab.h>
21 #include <linux/buffer_head.h>
22 #include <linux/blkdev.h>
23 #include <linux/random.h>
24 #include <linux/iocontext.h>
25 #include <linux/capability.h>
26 #include <linux/kthread.h>
27 #include <linux/math64.h>
28 #include <asm/div64.h>
29 #include "ctree.h"
30 #include "extent_map.h"
31 #include "disk-io.h"
32 #include "transaction.h"
33 #include "print-tree.h"
34 #include "volumes.h"
35 #include "async-thread.h"
36 #include "check-integrity.h"
37 #include "rcu-string.h"
38 #include "dev-replace.h"
39 #include "sysfs.h"
40 
41 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
42 				       int scrub_ret);
43 static void btrfs_dev_replace_update_device_in_mapping_tree(
44 						struct btrfs_fs_info *fs_info,
45 						struct btrfs_device *srcdev,
46 						struct btrfs_device *tgtdev);
47 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
48 					 char *srcdev_name,
49 					 struct btrfs_device **device);
50 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info);
51 static int btrfs_dev_replace_kthread(void *data);
52 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
53 
54 
55 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
56 {
57 	struct btrfs_key key;
58 	struct btrfs_root *dev_root = fs_info->dev_root;
59 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
60 	struct extent_buffer *eb;
61 	int slot;
62 	int ret = 0;
63 	struct btrfs_path *path = NULL;
64 	int item_size;
65 	struct btrfs_dev_replace_item *ptr;
66 	u64 src_devid;
67 
68 	path = btrfs_alloc_path();
69 	if (!path) {
70 		ret = -ENOMEM;
71 		goto out;
72 	}
73 
74 	key.objectid = 0;
75 	key.type = BTRFS_DEV_REPLACE_KEY;
76 	key.offset = 0;
77 	ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
78 	if (ret) {
79 no_valid_dev_replace_entry_found:
80 		ret = 0;
81 		dev_replace->replace_state =
82 			BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
83 		dev_replace->cont_reading_from_srcdev_mode =
84 		    BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
85 		dev_replace->replace_state = 0;
86 		dev_replace->time_started = 0;
87 		dev_replace->time_stopped = 0;
88 		atomic64_set(&dev_replace->num_write_errors, 0);
89 		atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
90 		dev_replace->cursor_left = 0;
91 		dev_replace->committed_cursor_left = 0;
92 		dev_replace->cursor_left_last_write_of_item = 0;
93 		dev_replace->cursor_right = 0;
94 		dev_replace->srcdev = NULL;
95 		dev_replace->tgtdev = NULL;
96 		dev_replace->is_valid = 0;
97 		dev_replace->item_needs_writeback = 0;
98 		goto out;
99 	}
100 	slot = path->slots[0];
101 	eb = path->nodes[0];
102 	item_size = btrfs_item_size_nr(eb, slot);
103 	ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
104 
105 	if (item_size != sizeof(struct btrfs_dev_replace_item)) {
106 		btrfs_warn(fs_info,
107 			"dev_replace entry found has unexpected size, ignore entry");
108 		goto no_valid_dev_replace_entry_found;
109 	}
110 
111 	src_devid = btrfs_dev_replace_src_devid(eb, ptr);
112 	dev_replace->cont_reading_from_srcdev_mode =
113 		btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
114 	dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
115 	dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
116 	dev_replace->time_stopped =
117 		btrfs_dev_replace_time_stopped(eb, ptr);
118 	atomic64_set(&dev_replace->num_write_errors,
119 		     btrfs_dev_replace_num_write_errors(eb, ptr));
120 	atomic64_set(&dev_replace->num_uncorrectable_read_errors,
121 		     btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
122 	dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
123 	dev_replace->committed_cursor_left = dev_replace->cursor_left;
124 	dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
125 	dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
126 	dev_replace->is_valid = 1;
127 
128 	dev_replace->item_needs_writeback = 0;
129 	switch (dev_replace->replace_state) {
130 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
131 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
132 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
133 		dev_replace->srcdev = NULL;
134 		dev_replace->tgtdev = NULL;
135 		break;
136 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
137 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
138 		dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
139 							NULL, NULL);
140 		dev_replace->tgtdev = btrfs_find_device(fs_info,
141 							BTRFS_DEV_REPLACE_DEVID,
142 							NULL, NULL);
143 		/*
144 		 * allow 'btrfs dev replace_cancel' if src/tgt device is
145 		 * missing
146 		 */
147 		if (!dev_replace->srcdev &&
148 		    !btrfs_test_opt(dev_root, DEGRADED)) {
149 			ret = -EIO;
150 			btrfs_warn(fs_info,
151 			   "cannot mount because device replace operation is ongoing and");
152 			btrfs_warn(fs_info,
153 			   "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
154 			   src_devid);
155 		}
156 		if (!dev_replace->tgtdev &&
157 		    !btrfs_test_opt(dev_root, DEGRADED)) {
158 			ret = -EIO;
159 			btrfs_warn(fs_info,
160 			   "cannot mount because device replace operation is ongoing and");
161 			btrfs_warn(fs_info,
162 			   "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
163 				BTRFS_DEV_REPLACE_DEVID);
164 		}
165 		if (dev_replace->tgtdev) {
166 			if (dev_replace->srcdev) {
167 				dev_replace->tgtdev->total_bytes =
168 					dev_replace->srcdev->total_bytes;
169 				dev_replace->tgtdev->disk_total_bytes =
170 					dev_replace->srcdev->disk_total_bytes;
171 				dev_replace->tgtdev->commit_total_bytes =
172 					dev_replace->srcdev->commit_total_bytes;
173 				dev_replace->tgtdev->bytes_used =
174 					dev_replace->srcdev->bytes_used;
175 				dev_replace->tgtdev->commit_bytes_used =
176 					dev_replace->srcdev->commit_bytes_used;
177 			}
178 			dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
179 			btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
180 				dev_replace->tgtdev);
181 		}
182 		break;
183 	}
184 
185 out:
186 	if (path)
187 		btrfs_free_path(path);
188 	return ret;
189 }
190 
191 /*
192  * called from commit_transaction. Writes changed device replace state to
193  * disk.
194  */
195 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
196 			  struct btrfs_fs_info *fs_info)
197 {
198 	int ret;
199 	struct btrfs_root *dev_root = fs_info->dev_root;
200 	struct btrfs_path *path;
201 	struct btrfs_key key;
202 	struct extent_buffer *eb;
203 	struct btrfs_dev_replace_item *ptr;
204 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
205 
206 	btrfs_dev_replace_lock(dev_replace);
207 	if (!dev_replace->is_valid ||
208 	    !dev_replace->item_needs_writeback) {
209 		btrfs_dev_replace_unlock(dev_replace);
210 		return 0;
211 	}
212 	btrfs_dev_replace_unlock(dev_replace);
213 
214 	key.objectid = 0;
215 	key.type = BTRFS_DEV_REPLACE_KEY;
216 	key.offset = 0;
217 
218 	path = btrfs_alloc_path();
219 	if (!path) {
220 		ret = -ENOMEM;
221 		goto out;
222 	}
223 	ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
224 	if (ret < 0) {
225 		btrfs_warn(fs_info, "error %d while searching for dev_replace item!",
226 			ret);
227 		goto out;
228 	}
229 
230 	if (ret == 0 &&
231 	    btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
232 		/*
233 		 * need to delete old one and insert a new one.
234 		 * Since no attempt is made to recover any old state, if the
235 		 * dev_replace state is 'running', the data on the target
236 		 * drive is lost.
237 		 * It would be possible to recover the state: just make sure
238 		 * that the beginning of the item is never changed and always
239 		 * contains all the essential information. Then read this
240 		 * minimal set of information and use it as a base for the
241 		 * new state.
242 		 */
243 		ret = btrfs_del_item(trans, dev_root, path);
244 		if (ret != 0) {
245 			btrfs_warn(fs_info, "delete too small dev_replace item failed %d!",
246 				ret);
247 			goto out;
248 		}
249 		ret = 1;
250 	}
251 
252 	if (ret == 1) {
253 		/* need to insert a new item */
254 		btrfs_release_path(path);
255 		ret = btrfs_insert_empty_item(trans, dev_root, path,
256 					      &key, sizeof(*ptr));
257 		if (ret < 0) {
258 			btrfs_warn(fs_info, "insert dev_replace item failed %d!",
259 				ret);
260 			goto out;
261 		}
262 	}
263 
264 	eb = path->nodes[0];
265 	ptr = btrfs_item_ptr(eb, path->slots[0],
266 			     struct btrfs_dev_replace_item);
267 
268 	btrfs_dev_replace_lock(dev_replace);
269 	if (dev_replace->srcdev)
270 		btrfs_set_dev_replace_src_devid(eb, ptr,
271 			dev_replace->srcdev->devid);
272 	else
273 		btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
274 	btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
275 		dev_replace->cont_reading_from_srcdev_mode);
276 	btrfs_set_dev_replace_replace_state(eb, ptr,
277 		dev_replace->replace_state);
278 	btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
279 	btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
280 	btrfs_set_dev_replace_num_write_errors(eb, ptr,
281 		atomic64_read(&dev_replace->num_write_errors));
282 	btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
283 		atomic64_read(&dev_replace->num_uncorrectable_read_errors));
284 	dev_replace->cursor_left_last_write_of_item =
285 		dev_replace->cursor_left;
286 	btrfs_set_dev_replace_cursor_left(eb, ptr,
287 		dev_replace->cursor_left_last_write_of_item);
288 	btrfs_set_dev_replace_cursor_right(eb, ptr,
289 		dev_replace->cursor_right);
290 	dev_replace->item_needs_writeback = 0;
291 	btrfs_dev_replace_unlock(dev_replace);
292 
293 	btrfs_mark_buffer_dirty(eb);
294 
295 out:
296 	btrfs_free_path(path);
297 
298 	return ret;
299 }
300 
301 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
302 {
303 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
304 
305 	dev_replace->committed_cursor_left =
306 		dev_replace->cursor_left_last_write_of_item;
307 }
308 
309 int btrfs_dev_replace_start(struct btrfs_root *root,
310 			    struct btrfs_ioctl_dev_replace_args *args)
311 {
312 	struct btrfs_trans_handle *trans;
313 	struct btrfs_fs_info *fs_info = root->fs_info;
314 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
315 	int ret;
316 	struct btrfs_device *tgt_device = NULL;
317 	struct btrfs_device *src_device = NULL;
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 	/*
332 	 * Here we commit the transaction to make sure commit_total_bytes
333 	 * of all the devices are updated.
334 	 */
335 	trans = btrfs_attach_transaction(root);
336 	if (!IS_ERR(trans)) {
337 		ret = btrfs_commit_transaction(trans, root);
338 		if (ret)
339 			return ret;
340 	} else if (PTR_ERR(trans) != -ENOENT) {
341 		return PTR_ERR(trans);
342 	}
343 
344 	/* the disk copy procedure reuses the scrub code */
345 	mutex_lock(&fs_info->volume_mutex);
346 	ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
347 					    args->start.srcdev_name,
348 					    &src_device);
349 	if (ret) {
350 		mutex_unlock(&fs_info->volume_mutex);
351 		return ret;
352 	}
353 
354 	ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
355 					    src_device, &tgt_device);
356 	mutex_unlock(&fs_info->volume_mutex);
357 	if (ret)
358 		return ret;
359 
360 	btrfs_dev_replace_lock(dev_replace);
361 	switch (dev_replace->replace_state) {
362 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
363 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
364 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
365 		break;
366 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
367 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
368 		args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
369 		goto leave;
370 	}
371 
372 	dev_replace->cont_reading_from_srcdev_mode =
373 		args->start.cont_reading_from_srcdev_mode;
374 	WARN_ON(!src_device);
375 	dev_replace->srcdev = src_device;
376 	WARN_ON(!tgt_device);
377 	dev_replace->tgtdev = tgt_device;
378 
379 	printk_in_rcu(KERN_INFO
380 		      "BTRFS: dev_replace from %s (devid %llu) to %s started\n",
381 		      src_device->missing ? "<missing disk>" :
382 		        rcu_str_deref(src_device->name),
383 		      src_device->devid,
384 		      rcu_str_deref(tgt_device->name));
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 			      btrfs_device_get_total_bytes(src_device),
417 			      &dev_replace->scrub_progress, 0, 1);
418 
419 	ret = btrfs_dev_replace_finishing(root->fs_info, ret);
420 	/* don't warn if EINPROGRESS, someone else might be running scrub */
421 	if (ret == -EINPROGRESS) {
422 		args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
423 		ret = 0;
424 	} else {
425 		WARN_ON(ret);
426 	}
427 
428 	return ret;
429 
430 leave:
431 	dev_replace->srcdev = NULL;
432 	dev_replace->tgtdev = NULL;
433 	btrfs_dev_replace_unlock(dev_replace);
434 	btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
435 	return ret;
436 }
437 
438 /*
439  * blocked until all flighting bios are finished.
440  */
441 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
442 {
443 	set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
444 	wait_event(fs_info->replace_wait, !percpu_counter_sum(
445 		   &fs_info->bio_counter));
446 }
447 
448 /*
449  * we have removed target device, it is safe to allow new bios request.
450  */
451 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
452 {
453 	clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
454 	if (waitqueue_active(&fs_info->replace_wait))
455 		wake_up(&fs_info->replace_wait);
456 }
457 
458 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
459 				       int scrub_ret)
460 {
461 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
462 	struct btrfs_device *tgt_device;
463 	struct btrfs_device *src_device;
464 	struct btrfs_root *root = fs_info->tree_root;
465 	u8 uuid_tmp[BTRFS_UUID_SIZE];
466 	struct btrfs_trans_handle *trans;
467 	int ret = 0;
468 
469 	/* don't allow cancel or unmount to disturb the finishing procedure */
470 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
471 
472 	btrfs_dev_replace_lock(dev_replace);
473 	/* was the operation canceled, or is it finished? */
474 	if (dev_replace->replace_state !=
475 	    BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
476 		btrfs_dev_replace_unlock(dev_replace);
477 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
478 		return 0;
479 	}
480 
481 	tgt_device = dev_replace->tgtdev;
482 	src_device = dev_replace->srcdev;
483 	btrfs_dev_replace_unlock(dev_replace);
484 
485 	/*
486 	 * flush all outstanding I/O and inode extent mappings before the
487 	 * copy operation is declared as being finished
488 	 */
489 	ret = btrfs_start_delalloc_roots(root->fs_info, 0, -1);
490 	if (ret) {
491 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
492 		return ret;
493 	}
494 	btrfs_wait_ordered_roots(root->fs_info, -1);
495 
496 	trans = btrfs_start_transaction(root, 0);
497 	if (IS_ERR(trans)) {
498 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
499 		return PTR_ERR(trans);
500 	}
501 	ret = btrfs_commit_transaction(trans, root);
502 	WARN_ON(ret);
503 
504 	mutex_lock(&uuid_mutex);
505 	/* keep away write_all_supers() during the finishing procedure */
506 	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
507 	mutex_lock(&root->fs_info->chunk_mutex);
508 	btrfs_dev_replace_lock(dev_replace);
509 	dev_replace->replace_state =
510 		scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
511 			  : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
512 	dev_replace->tgtdev = NULL;
513 	dev_replace->srcdev = NULL;
514 	dev_replace->time_stopped = get_seconds();
515 	dev_replace->item_needs_writeback = 1;
516 
517 	/* replace old device with new one in mapping tree */
518 	if (!scrub_ret) {
519 		btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
520 								src_device,
521 								tgt_device);
522 	} else {
523 		printk_in_rcu(KERN_ERR
524 			      "BTRFS: btrfs_scrub_dev(%s, %llu, %s) failed %d\n",
525 			      src_device->missing ? "<missing disk>" :
526 			        rcu_str_deref(src_device->name),
527 			      src_device->devid,
528 			      rcu_str_deref(tgt_device->name), scrub_ret);
529 		btrfs_dev_replace_unlock(dev_replace);
530 		mutex_unlock(&root->fs_info->chunk_mutex);
531 		mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
532 		mutex_unlock(&uuid_mutex);
533 		if (tgt_device)
534 			btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
535 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
536 
537 		return scrub_ret;
538 	}
539 
540 	printk_in_rcu(KERN_INFO
541 		      "BTRFS: dev_replace from %s (devid %llu) to %s finished\n",
542 		      src_device->missing ? "<missing disk>" :
543 		        rcu_str_deref(src_device->name),
544 		      src_device->devid,
545 		      rcu_str_deref(tgt_device->name));
546 	tgt_device->is_tgtdev_for_dev_replace = 0;
547 	tgt_device->devid = src_device->devid;
548 	src_device->devid = BTRFS_DEV_REPLACE_DEVID;
549 	memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
550 	memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
551 	memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
552 	btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
553 	btrfs_device_set_disk_total_bytes(tgt_device,
554 					  src_device->disk_total_bytes);
555 	btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
556 	ASSERT(list_empty(&src_device->resized_list));
557 	tgt_device->commit_total_bytes = src_device->commit_total_bytes;
558 	tgt_device->commit_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 	fs_info->fs_devices->rw_devices++;
565 
566 	btrfs_dev_replace_unlock(dev_replace);
567 
568 	btrfs_rm_dev_replace_blocked(fs_info);
569 
570 	btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
571 
572 	btrfs_rm_dev_replace_unblocked(fs_info);
573 
574 	/*
575 	 * this is again a consistent state where no dev_replace procedure
576 	 * is running, the target device is part of the filesystem, the
577 	 * source device is not part of the filesystem anymore and its 1st
578 	 * superblock is scratched out so that it is no longer marked to
579 	 * belong to this filesystem.
580 	 */
581 	mutex_unlock(&root->fs_info->chunk_mutex);
582 	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
583 	mutex_unlock(&uuid_mutex);
584 
585 	/* replace the sysfs entry */
586 	btrfs_kobj_rm_device(fs_info, src_device);
587 	btrfs_kobj_add_device(fs_info, tgt_device);
588 	btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
589 
590 	/* write back the superblocks */
591 	trans = btrfs_start_transaction(root, 0);
592 	if (!IS_ERR(trans))
593 		btrfs_commit_transaction(trans, root);
594 
595 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
596 
597 	return 0;
598 }
599 
600 static void btrfs_dev_replace_update_device_in_mapping_tree(
601 						struct btrfs_fs_info *fs_info,
602 						struct btrfs_device *srcdev,
603 						struct btrfs_device *tgtdev)
604 {
605 	struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
606 	struct extent_map *em;
607 	struct map_lookup *map;
608 	u64 start = 0;
609 	int i;
610 
611 	write_lock(&em_tree->lock);
612 	do {
613 		em = lookup_extent_mapping(em_tree, start, (u64)-1);
614 		if (!em)
615 			break;
616 		map = (struct map_lookup *)em->bdev;
617 		for (i = 0; i < map->num_stripes; i++)
618 			if (srcdev == map->stripes[i].dev)
619 				map->stripes[i].dev = tgtdev;
620 		start = em->start + em->len;
621 		free_extent_map(em);
622 	} while (start);
623 	write_unlock(&em_tree->lock);
624 }
625 
626 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
627 					 char *srcdev_name,
628 					 struct btrfs_device **device)
629 {
630 	int ret;
631 
632 	if (srcdevid) {
633 		ret = 0;
634 		*device = btrfs_find_device(root->fs_info, srcdevid, NULL,
635 					    NULL);
636 		if (!*device)
637 			ret = -ENOENT;
638 	} else {
639 		ret = btrfs_find_device_missing_or_by_path(root, srcdev_name,
640 							   device);
641 	}
642 	return ret;
643 }
644 
645 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
646 			      struct btrfs_ioctl_dev_replace_args *args)
647 {
648 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
649 	struct btrfs_device *srcdev;
650 
651 	btrfs_dev_replace_lock(dev_replace);
652 	/* even if !dev_replace_is_valid, the values are good enough for
653 	 * the replace_status ioctl */
654 	args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
655 	args->status.replace_state = dev_replace->replace_state;
656 	args->status.time_started = dev_replace->time_started;
657 	args->status.time_stopped = dev_replace->time_stopped;
658 	args->status.num_write_errors =
659 		atomic64_read(&dev_replace->num_write_errors);
660 	args->status.num_uncorrectable_read_errors =
661 		atomic64_read(&dev_replace->num_uncorrectable_read_errors);
662 	switch (dev_replace->replace_state) {
663 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
664 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
665 		args->status.progress_1000 = 0;
666 		break;
667 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
668 		args->status.progress_1000 = 1000;
669 		break;
670 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
671 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
672 		srcdev = dev_replace->srcdev;
673 		args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
674 			div64_u64(btrfs_device_get_total_bytes(srcdev), 1000));
675 		break;
676 	}
677 	btrfs_dev_replace_unlock(dev_replace);
678 }
679 
680 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
681 			     struct btrfs_ioctl_dev_replace_args *args)
682 {
683 	args->result = __btrfs_dev_replace_cancel(fs_info);
684 	return 0;
685 }
686 
687 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
688 {
689 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
690 	struct btrfs_device *tgt_device = NULL;
691 	struct btrfs_trans_handle *trans;
692 	struct btrfs_root *root = fs_info->tree_root;
693 	u64 result;
694 	int ret;
695 
696 	if (fs_info->sb->s_flags & MS_RDONLY)
697 		return -EROFS;
698 
699 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
700 	btrfs_dev_replace_lock(dev_replace);
701 	switch (dev_replace->replace_state) {
702 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
703 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
704 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
705 		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
706 		btrfs_dev_replace_unlock(dev_replace);
707 		goto leave;
708 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
709 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
710 		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
711 		tgt_device = dev_replace->tgtdev;
712 		dev_replace->tgtdev = NULL;
713 		dev_replace->srcdev = NULL;
714 		break;
715 	}
716 	dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
717 	dev_replace->time_stopped = get_seconds();
718 	dev_replace->item_needs_writeback = 1;
719 	btrfs_dev_replace_unlock(dev_replace);
720 	btrfs_scrub_cancel(fs_info);
721 
722 	trans = btrfs_start_transaction(root, 0);
723 	if (IS_ERR(trans)) {
724 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
725 		return PTR_ERR(trans);
726 	}
727 	ret = btrfs_commit_transaction(trans, root);
728 	WARN_ON(ret);
729 	if (tgt_device)
730 		btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
731 
732 leave:
733 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
734 	return result;
735 }
736 
737 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
738 {
739 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
740 
741 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
742 	btrfs_dev_replace_lock(dev_replace);
743 	switch (dev_replace->replace_state) {
744 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
745 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
746 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
747 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
748 		break;
749 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
750 		dev_replace->replace_state =
751 			BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
752 		dev_replace->time_stopped = get_seconds();
753 		dev_replace->item_needs_writeback = 1;
754 		btrfs_info(fs_info, "suspending dev_replace for unmount");
755 		break;
756 	}
757 
758 	btrfs_dev_replace_unlock(dev_replace);
759 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
760 }
761 
762 /* resume dev_replace procedure that was interrupted by unmount */
763 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
764 {
765 	struct task_struct *task;
766 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
767 
768 	btrfs_dev_replace_lock(dev_replace);
769 	switch (dev_replace->replace_state) {
770 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
771 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
772 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
773 		btrfs_dev_replace_unlock(dev_replace);
774 		return 0;
775 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
776 		break;
777 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
778 		dev_replace->replace_state =
779 			BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
780 		break;
781 	}
782 	if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
783 		btrfs_info(fs_info, "cannot continue dev_replace, tgtdev is missing");
784 		btrfs_info(fs_info,
785 			"you may cancel the operation after 'mount -o degraded'");
786 		btrfs_dev_replace_unlock(dev_replace);
787 		return 0;
788 	}
789 	btrfs_dev_replace_unlock(dev_replace);
790 
791 	WARN_ON(atomic_xchg(
792 		&fs_info->mutually_exclusive_operation_running, 1));
793 	task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
794 	return PTR_ERR_OR_ZERO(task);
795 }
796 
797 static int btrfs_dev_replace_kthread(void *data)
798 {
799 	struct btrfs_fs_info *fs_info = data;
800 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
801 	struct btrfs_ioctl_dev_replace_args *status_args;
802 	u64 progress;
803 
804 	status_args = kzalloc(sizeof(*status_args), GFP_NOFS);
805 	if (status_args) {
806 		btrfs_dev_replace_status(fs_info, status_args);
807 		progress = status_args->status.progress_1000;
808 		kfree(status_args);
809 		do_div(progress, 10);
810 		printk_in_rcu(KERN_INFO
811 			"BTRFS: continuing dev_replace from %s (devid %llu) to %s @%u%%\n",
812 			dev_replace->srcdev->missing ? "<missing disk>" :
813 			rcu_str_deref(dev_replace->srcdev->name),
814 			dev_replace->srcdev->devid,
815 			dev_replace->tgtdev ?
816 			rcu_str_deref(dev_replace->tgtdev->name) :
817 			"<missing target disk>",
818 			(unsigned int)progress);
819 	}
820 	btrfs_dev_replace_continue_on_mount(fs_info);
821 	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
822 
823 	return 0;
824 }
825 
826 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
827 {
828 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
829 	int ret;
830 
831 	ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
832 			      dev_replace->committed_cursor_left,
833 			      btrfs_device_get_total_bytes(dev_replace->srcdev),
834 			      &dev_replace->scrub_progress, 0, 1);
835 	ret = btrfs_dev_replace_finishing(fs_info, ret);
836 	WARN_ON(ret);
837 	return 0;
838 }
839 
840 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
841 {
842 	if (!dev_replace->is_valid)
843 		return 0;
844 
845 	switch (dev_replace->replace_state) {
846 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
847 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
848 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
849 		return 0;
850 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
851 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
852 		/*
853 		 * return true even if tgtdev is missing (this is
854 		 * something that can happen if the dev_replace
855 		 * procedure is suspended by an umount and then
856 		 * the tgtdev is missing (or "btrfs dev scan") was
857 		 * not called and the the filesystem is remounted
858 		 * in degraded state. This does not stop the
859 		 * dev_replace procedure. It needs to be canceled
860 		 * manually if the cancelation is wanted.
861 		 */
862 		break;
863 	}
864 	return 1;
865 }
866 
867 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
868 {
869 	/* the beginning is just an optimization for the typical case */
870 	if (atomic_read(&dev_replace->nesting_level) == 0) {
871 acquire_lock:
872 		/* this is not a nested case where the same thread
873 		 * is trying to acqurire the same lock twice */
874 		mutex_lock(&dev_replace->lock);
875 		mutex_lock(&dev_replace->lock_management_lock);
876 		dev_replace->lock_owner = current->pid;
877 		atomic_inc(&dev_replace->nesting_level);
878 		mutex_unlock(&dev_replace->lock_management_lock);
879 		return;
880 	}
881 
882 	mutex_lock(&dev_replace->lock_management_lock);
883 	if (atomic_read(&dev_replace->nesting_level) > 0 &&
884 	    dev_replace->lock_owner == current->pid) {
885 		WARN_ON(!mutex_is_locked(&dev_replace->lock));
886 		atomic_inc(&dev_replace->nesting_level);
887 		mutex_unlock(&dev_replace->lock_management_lock);
888 		return;
889 	}
890 
891 	mutex_unlock(&dev_replace->lock_management_lock);
892 	goto acquire_lock;
893 }
894 
895 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
896 {
897 	WARN_ON(!mutex_is_locked(&dev_replace->lock));
898 	mutex_lock(&dev_replace->lock_management_lock);
899 	WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
900 	WARN_ON(dev_replace->lock_owner != current->pid);
901 	atomic_dec(&dev_replace->nesting_level);
902 	if (atomic_read(&dev_replace->nesting_level) == 0) {
903 		dev_replace->lock_owner = 0;
904 		mutex_unlock(&dev_replace->lock_management_lock);
905 		mutex_unlock(&dev_replace->lock);
906 	} else {
907 		mutex_unlock(&dev_replace->lock_management_lock);
908 	}
909 }
910 
911 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
912 {
913 	percpu_counter_inc(&fs_info->bio_counter);
914 }
915 
916 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
917 {
918 	percpu_counter_sub(&fs_info->bio_counter, amount);
919 
920 	if (waitqueue_active(&fs_info->replace_wait))
921 		wake_up(&fs_info->replace_wait);
922 }
923 
924 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
925 {
926 	while (1) {
927 		percpu_counter_inc(&fs_info->bio_counter);
928 		if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
929 				     &fs_info->fs_state)))
930 			break;
931 
932 		btrfs_bio_counter_dec(fs_info);
933 		wait_event(fs_info->replace_wait,
934 			   !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
935 				     &fs_info->fs_state));
936 	}
937 }
938