GNU Linux-libre 4.9.308-gnu1
[releases.git] / fs / btrfs / dev-replace.c
1 /*
2  * Copyright (C) STRATO AG 2012.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18 #include <linux/sched.h>
19 #include <linux/bio.h>
20 #include <linux/slab.h>
21 #include <linux/buffer_head.h>
22 #include <linux/blkdev.h>
23 #include <linux/random.h>
24 #include <linux/iocontext.h>
25 #include <linux/capability.h>
26 #include <linux/kthread.h>
27 #include <linux/math64.h>
28 #include <asm/div64.h>
29 #include "ctree.h"
30 #include "extent_map.h"
31 #include "disk-io.h"
32 #include "transaction.h"
33 #include "print-tree.h"
34 #include "volumes.h"
35 #include "async-thread.h"
36 #include "check-integrity.h"
37 #include "rcu-string.h"
38 #include "dev-replace.h"
39 #include "sysfs.h"
40
41 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
42                                        int scrub_ret);
43 static void btrfs_dev_replace_update_device_in_mapping_tree(
44                                                 struct btrfs_fs_info *fs_info,
45                                                 struct btrfs_device *srcdev,
46                                                 struct btrfs_device *tgtdev);
47 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info);
48 static int btrfs_dev_replace_kthread(void *data);
49 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
50
51
52 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
53 {
54         struct btrfs_key key;
55         struct btrfs_root *dev_root = fs_info->dev_root;
56         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
57         struct extent_buffer *eb;
58         int slot;
59         int ret = 0;
60         struct btrfs_path *path = NULL;
61         int item_size;
62         struct btrfs_dev_replace_item *ptr;
63         u64 src_devid;
64
65         path = btrfs_alloc_path();
66         if (!path) {
67                 ret = -ENOMEM;
68                 goto out;
69         }
70
71         key.objectid = 0;
72         key.type = BTRFS_DEV_REPLACE_KEY;
73         key.offset = 0;
74         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
75         if (ret) {
76 no_valid_dev_replace_entry_found:
77                 ret = 0;
78                 dev_replace->replace_state =
79                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
80                 dev_replace->cont_reading_from_srcdev_mode =
81                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
82                 dev_replace->replace_state = 0;
83                 dev_replace->time_started = 0;
84                 dev_replace->time_stopped = 0;
85                 atomic64_set(&dev_replace->num_write_errors, 0);
86                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
87                 dev_replace->cursor_left = 0;
88                 dev_replace->committed_cursor_left = 0;
89                 dev_replace->cursor_left_last_write_of_item = 0;
90                 dev_replace->cursor_right = 0;
91                 dev_replace->srcdev = NULL;
92                 dev_replace->tgtdev = NULL;
93                 dev_replace->is_valid = 0;
94                 dev_replace->item_needs_writeback = 0;
95                 goto out;
96         }
97         slot = path->slots[0];
98         eb = path->nodes[0];
99         item_size = btrfs_item_size_nr(eb, slot);
100         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
101
102         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
103                 btrfs_warn(fs_info,
104                         "dev_replace entry found has unexpected size, ignore entry");
105                 goto no_valid_dev_replace_entry_found;
106         }
107
108         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
109         dev_replace->cont_reading_from_srcdev_mode =
110                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
111         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
112         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
113         dev_replace->time_stopped =
114                 btrfs_dev_replace_time_stopped(eb, ptr);
115         atomic64_set(&dev_replace->num_write_errors,
116                      btrfs_dev_replace_num_write_errors(eb, ptr));
117         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
118                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
119         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
120         dev_replace->committed_cursor_left = dev_replace->cursor_left;
121         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
122         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
123         dev_replace->is_valid = 1;
124
125         dev_replace->item_needs_writeback = 0;
126         switch (dev_replace->replace_state) {
127         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
128         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
129         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
130                 dev_replace->srcdev = NULL;
131                 dev_replace->tgtdev = NULL;
132                 break;
133         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
134         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
135                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
136                                                         NULL, NULL);
137                 dev_replace->tgtdev = btrfs_find_device(fs_info,
138                                                         BTRFS_DEV_REPLACE_DEVID,
139                                                         NULL, NULL);
140                 /*
141                  * allow 'btrfs dev replace_cancel' if src/tgt device is
142                  * missing
143                  */
144                 if (!dev_replace->srcdev &&
145                     !btrfs_test_opt(dev_root->fs_info, DEGRADED)) {
146                         ret = -EIO;
147                         btrfs_warn(fs_info,
148                            "cannot mount because device replace operation is ongoing and");
149                         btrfs_warn(fs_info,
150                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
151                            src_devid);
152                 }
153                 if (!dev_replace->tgtdev &&
154                     !btrfs_test_opt(dev_root->fs_info, DEGRADED)) {
155                         ret = -EIO;
156                         btrfs_warn(fs_info,
157                            "cannot mount because device replace operation is ongoing and");
158                         btrfs_warn(fs_info,
159                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
160                                 BTRFS_DEV_REPLACE_DEVID);
161                 }
162                 if (dev_replace->tgtdev) {
163                         if (dev_replace->srcdev) {
164                                 dev_replace->tgtdev->total_bytes =
165                                         dev_replace->srcdev->total_bytes;
166                                 dev_replace->tgtdev->disk_total_bytes =
167                                         dev_replace->srcdev->disk_total_bytes;
168                                 dev_replace->tgtdev->commit_total_bytes =
169                                         dev_replace->srcdev->commit_total_bytes;
170                                 dev_replace->tgtdev->bytes_used =
171                                         dev_replace->srcdev->bytes_used;
172                                 dev_replace->tgtdev->commit_bytes_used =
173                                         dev_replace->srcdev->commit_bytes_used;
174                         }
175                         dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
176                         btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
177                                 dev_replace->tgtdev);
178                 }
179                 break;
180         }
181
182 out:
183         btrfs_free_path(path);
184         return ret;
185 }
186
187 /*
188  * called from commit_transaction. Writes changed device replace state to
189  * disk.
190  */
191 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
192                           struct btrfs_fs_info *fs_info)
193 {
194         int ret;
195         struct btrfs_root *dev_root = fs_info->dev_root;
196         struct btrfs_path *path;
197         struct btrfs_key key;
198         struct extent_buffer *eb;
199         struct btrfs_dev_replace_item *ptr;
200         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
201
202         btrfs_dev_replace_lock(dev_replace, 0);
203         if (!dev_replace->is_valid ||
204             !dev_replace->item_needs_writeback) {
205                 btrfs_dev_replace_unlock(dev_replace, 0);
206                 return 0;
207         }
208         btrfs_dev_replace_unlock(dev_replace, 0);
209
210         key.objectid = 0;
211         key.type = BTRFS_DEV_REPLACE_KEY;
212         key.offset = 0;
213
214         path = btrfs_alloc_path();
215         if (!path) {
216                 ret = -ENOMEM;
217                 goto out;
218         }
219         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
220         if (ret < 0) {
221                 btrfs_warn(fs_info,
222                            "error %d while searching for dev_replace item!",
223                            ret);
224                 goto out;
225         }
226
227         if (ret == 0 &&
228             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
229                 /*
230                  * need to delete old one and insert a new one.
231                  * Since no attempt is made to recover any old state, if the
232                  * dev_replace state is 'running', the data on the target
233                  * drive is lost.
234                  * It would be possible to recover the state: just make sure
235                  * that the beginning of the item is never changed and always
236                  * contains all the essential information. Then read this
237                  * minimal set of information and use it as a base for the
238                  * new state.
239                  */
240                 ret = btrfs_del_item(trans, dev_root, path);
241                 if (ret != 0) {
242                         btrfs_warn(fs_info,
243                                    "delete too small dev_replace item failed %d!",
244                                    ret);
245                         goto out;
246                 }
247                 ret = 1;
248         }
249
250         if (ret == 1) {
251                 /* need to insert a new item */
252                 btrfs_release_path(path);
253                 ret = btrfs_insert_empty_item(trans, dev_root, path,
254                                               &key, sizeof(*ptr));
255                 if (ret < 0) {
256                         btrfs_warn(fs_info,
257                                    "insert dev_replace item failed %d!", ret);
258                         goto out;
259                 }
260         }
261
262         eb = path->nodes[0];
263         ptr = btrfs_item_ptr(eb, path->slots[0],
264                              struct btrfs_dev_replace_item);
265
266         btrfs_dev_replace_lock(dev_replace, 1);
267         if (dev_replace->srcdev)
268                 btrfs_set_dev_replace_src_devid(eb, ptr,
269                         dev_replace->srcdev->devid);
270         else
271                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
272         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
273                 dev_replace->cont_reading_from_srcdev_mode);
274         btrfs_set_dev_replace_replace_state(eb, ptr,
275                 dev_replace->replace_state);
276         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
277         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
278         btrfs_set_dev_replace_num_write_errors(eb, ptr,
279                 atomic64_read(&dev_replace->num_write_errors));
280         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
281                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
282         dev_replace->cursor_left_last_write_of_item =
283                 dev_replace->cursor_left;
284         btrfs_set_dev_replace_cursor_left(eb, ptr,
285                 dev_replace->cursor_left_last_write_of_item);
286         btrfs_set_dev_replace_cursor_right(eb, ptr,
287                 dev_replace->cursor_right);
288         dev_replace->item_needs_writeback = 0;
289         btrfs_dev_replace_unlock(dev_replace, 1);
290
291         btrfs_mark_buffer_dirty(eb);
292
293 out:
294         btrfs_free_path(path);
295
296         return ret;
297 }
298
299 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
300 {
301         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
302
303         dev_replace->committed_cursor_left =
304                 dev_replace->cursor_left_last_write_of_item;
305 }
306
307 int btrfs_dev_replace_start(struct btrfs_root *root, char *tgtdev_name,
308                                 u64 srcdevid, char *srcdev_name, int read_src)
309 {
310         struct btrfs_trans_handle *trans;
311         struct btrfs_fs_info *fs_info = root->fs_info;
312         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
313         int ret;
314         struct btrfs_device *tgt_device = NULL;
315         struct btrfs_device *src_device = NULL;
316
317         /* the disk copy procedure reuses the scrub code */
318         mutex_lock(&fs_info->volume_mutex);
319         ret = btrfs_find_device_by_devspec(root, srcdevid,
320                                             srcdev_name, &src_device);
321         if (ret) {
322                 mutex_unlock(&fs_info->volume_mutex);
323                 return ret;
324         }
325
326         ret = btrfs_init_dev_replace_tgtdev(root, tgtdev_name,
327                                             src_device, &tgt_device);
328         mutex_unlock(&fs_info->volume_mutex);
329         if (ret)
330                 return ret;
331
332         /*
333          * Here we commit the transaction to make sure commit_total_bytes
334          * of all the devices are updated.
335          */
336         trans = btrfs_attach_transaction(root);
337         if (!IS_ERR(trans)) {
338                 ret = btrfs_commit_transaction(trans, root);
339                 if (ret)
340                         return ret;
341         } else if (PTR_ERR(trans) != -ENOENT) {
342                 return PTR_ERR(trans);
343         }
344
345         btrfs_dev_replace_lock(dev_replace, 1);
346         switch (dev_replace->replace_state) {
347         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
348         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
349         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
350                 break;
351         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
352         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
353                 ASSERT(0);
354                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
355                 goto leave;
356         }
357
358         dev_replace->cont_reading_from_srcdev_mode = read_src;
359         WARN_ON(!src_device);
360         dev_replace->srcdev = src_device;
361         WARN_ON(!tgt_device);
362         dev_replace->tgtdev = tgt_device;
363
364         btrfs_info_in_rcu(fs_info,
365                       "dev_replace from %s (devid %llu) to %s started",
366                       src_device->missing ? "<missing disk>" :
367                         rcu_str_deref(src_device->name),
368                       src_device->devid,
369                       rcu_str_deref(tgt_device->name));
370
371         /*
372          * from now on, the writes to the srcdev are all duplicated to
373          * go to the tgtdev as well (refer to btrfs_map_block()).
374          */
375         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
376         dev_replace->time_started = get_seconds();
377         dev_replace->cursor_left = 0;
378         dev_replace->committed_cursor_left = 0;
379         dev_replace->cursor_left_last_write_of_item = 0;
380         dev_replace->cursor_right = 0;
381         dev_replace->is_valid = 1;
382         dev_replace->item_needs_writeback = 1;
383         atomic64_set(&dev_replace->num_write_errors, 0);
384         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
385         btrfs_dev_replace_unlock(dev_replace, 1);
386
387         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
388         if (ret)
389                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
390
391         btrfs_wait_ordered_roots(root->fs_info, -1, 0, (u64)-1);
392
393         /* force writing the updated state information to disk */
394         trans = btrfs_start_transaction(root, 0);
395         if (IS_ERR(trans)) {
396                 ret = PTR_ERR(trans);
397                 btrfs_dev_replace_lock(dev_replace, 1);
398                 dev_replace->replace_state =
399                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
400                 dev_replace->srcdev = NULL;
401                 dev_replace->tgtdev = NULL;
402                 goto leave;
403         }
404
405         ret = btrfs_commit_transaction(trans, root);
406         WARN_ON(ret);
407
408         /* the disk copy procedure reuses the scrub code */
409         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
410                               btrfs_device_get_total_bytes(src_device),
411                               &dev_replace->scrub_progress, 0, 1);
412
413         ret = btrfs_dev_replace_finishing(fs_info, ret);
414         if (ret == -EINPROGRESS) {
415                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
416         } else {
417                 WARN_ON(ret);
418         }
419
420         return ret;
421
422 leave:
423         btrfs_dev_replace_unlock(dev_replace, 1);
424         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
425         return ret;
426 }
427
428 int btrfs_dev_replace_by_ioctl(struct btrfs_root *root,
429                             struct btrfs_ioctl_dev_replace_args *args)
430 {
431         int ret;
432
433         switch (args->start.cont_reading_from_srcdev_mode) {
434         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
435         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
436                 break;
437         default:
438                 return -EINVAL;
439         }
440
441         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
442             args->start.tgtdev_name[0] == '\0')
443                 return -EINVAL;
444
445         ret = btrfs_dev_replace_start(root, args->start.tgtdev_name,
446                                         args->start.srcdevid,
447                                         args->start.srcdev_name,
448                                         args->start.cont_reading_from_srcdev_mode);
449         args->result = ret;
450         /* don't warn if EINPROGRESS, someone else might be running scrub */
451         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
452                 ret = 0;
453
454         return ret;
455 }
456
457 /*
458  * blocked until all in-flight bios operations are finished.
459  */
460 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
461 {
462         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
463         wait_event(fs_info->replace_wait, !percpu_counter_sum(
464                    &fs_info->bio_counter));
465 }
466
467 /*
468  * we have removed target device, it is safe to allow new bios request.
469  */
470 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
471 {
472         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
473         wake_up(&fs_info->replace_wait);
474 }
475
476 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
477                                        int scrub_ret)
478 {
479         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
480         struct btrfs_device *tgt_device;
481         struct btrfs_device *src_device;
482         struct btrfs_root *root = fs_info->tree_root;
483         u8 uuid_tmp[BTRFS_UUID_SIZE];
484         struct btrfs_trans_handle *trans;
485         int ret = 0;
486
487         /* don't allow cancel or unmount to disturb the finishing procedure */
488         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
489
490         btrfs_dev_replace_lock(dev_replace, 0);
491         /* was the operation canceled, or is it finished? */
492         if (dev_replace->replace_state !=
493             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
494                 btrfs_dev_replace_unlock(dev_replace, 0);
495                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
496                 return 0;
497         }
498
499         tgt_device = dev_replace->tgtdev;
500         src_device = dev_replace->srcdev;
501         btrfs_dev_replace_unlock(dev_replace, 0);
502
503         /*
504          * flush all outstanding I/O and inode extent mappings before the
505          * copy operation is declared as being finished
506          */
507         ret = btrfs_start_delalloc_roots(root->fs_info, 0, -1);
508         if (ret) {
509                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
510                 return ret;
511         }
512         btrfs_wait_ordered_roots(root->fs_info, -1, 0, (u64)-1);
513
514         while (1) {
515                 trans = btrfs_start_transaction(root, 0);
516                 if (IS_ERR(trans)) {
517                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
518                         return PTR_ERR(trans);
519                 }
520                 ret = btrfs_commit_transaction(trans, root);
521                 WARN_ON(ret);
522                 mutex_lock(&uuid_mutex);
523                 /* keep away write_all_supers() during the finishing procedure */
524                 mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
525                 mutex_lock(&root->fs_info->chunk_mutex);
526                 if (src_device->has_pending_chunks) {
527                         mutex_unlock(&root->fs_info->chunk_mutex);
528                         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
529                         mutex_unlock(&uuid_mutex);
530                 } else {
531                         break;
532                 }
533         }
534
535         btrfs_dev_replace_lock(dev_replace, 1);
536         dev_replace->replace_state =
537                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
538                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
539         dev_replace->tgtdev = NULL;
540         dev_replace->srcdev = NULL;
541         dev_replace->time_stopped = get_seconds();
542         dev_replace->item_needs_writeback = 1;
543
544         /* replace old device with new one in mapping tree */
545         if (!scrub_ret) {
546                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
547                                                                 src_device,
548                                                                 tgt_device);
549         } else {
550                 btrfs_err_in_rcu(root->fs_info,
551                               "btrfs_scrub_dev(%s, %llu, %s) failed %d",
552                               src_device->missing ? "<missing disk>" :
553                                 rcu_str_deref(src_device->name),
554                               src_device->devid,
555                               rcu_str_deref(tgt_device->name), scrub_ret);
556                 btrfs_dev_replace_unlock(dev_replace, 1);
557                 mutex_unlock(&root->fs_info->chunk_mutex);
558                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
559                 mutex_unlock(&uuid_mutex);
560                 if (tgt_device)
561                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
562                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
563
564                 return scrub_ret;
565         }
566
567         btrfs_info_in_rcu(root->fs_info,
568                       "dev_replace from %s (devid %llu) to %s finished",
569                       src_device->missing ? "<missing disk>" :
570                         rcu_str_deref(src_device->name),
571                       src_device->devid,
572                       rcu_str_deref(tgt_device->name));
573         tgt_device->is_tgtdev_for_dev_replace = 0;
574         tgt_device->devid = src_device->devid;
575         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
576         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
577         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
578         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
579         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
580         btrfs_device_set_disk_total_bytes(tgt_device,
581                                           src_device->disk_total_bytes);
582         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
583         ASSERT(list_empty(&src_device->resized_list));
584         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
585         tgt_device->commit_bytes_used = src_device->bytes_used;
586
587         btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
588
589         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
590         fs_info->fs_devices->rw_devices++;
591
592         btrfs_dev_replace_unlock(dev_replace, 1);
593
594         btrfs_rm_dev_replace_blocked(fs_info);
595
596         btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
597
598         btrfs_rm_dev_replace_unblocked(fs_info);
599
600         /*
601          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
602          * update on-disk dev stats value during commit transaction
603          */
604         atomic_inc(&tgt_device->dev_stats_ccnt);
605
606         /*
607          * this is again a consistent state where no dev_replace procedure
608          * is running, the target device is part of the filesystem, the
609          * source device is not part of the filesystem anymore and its 1st
610          * superblock is scratched out so that it is no longer marked to
611          * belong to this filesystem.
612          */
613         mutex_unlock(&root->fs_info->chunk_mutex);
614         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
615         mutex_unlock(&uuid_mutex);
616
617         /* replace the sysfs entry */
618         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
619         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
620
621         /* write back the superblocks */
622         trans = btrfs_start_transaction(root, 0);
623         if (!IS_ERR(trans))
624                 btrfs_commit_transaction(trans, root);
625
626         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
627
628         return 0;
629 }
630
631 static void btrfs_dev_replace_update_device_in_mapping_tree(
632                                                 struct btrfs_fs_info *fs_info,
633                                                 struct btrfs_device *srcdev,
634                                                 struct btrfs_device *tgtdev)
635 {
636         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
637         struct extent_map *em;
638         struct map_lookup *map;
639         u64 start = 0;
640         int i;
641
642         write_lock(&em_tree->lock);
643         do {
644                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
645                 if (!em)
646                         break;
647                 map = em->map_lookup;
648                 for (i = 0; i < map->num_stripes; i++)
649                         if (srcdev == map->stripes[i].dev)
650                                 map->stripes[i].dev = tgtdev;
651                 start = em->start + em->len;
652                 free_extent_map(em);
653         } while (start);
654         write_unlock(&em_tree->lock);
655 }
656
657 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
658                               struct btrfs_ioctl_dev_replace_args *args)
659 {
660         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
661         struct btrfs_device *srcdev;
662
663         btrfs_dev_replace_lock(dev_replace, 0);
664         /* even if !dev_replace_is_valid, the values are good enough for
665          * the replace_status ioctl */
666         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
667         args->status.replace_state = dev_replace->replace_state;
668         args->status.time_started = dev_replace->time_started;
669         args->status.time_stopped = dev_replace->time_stopped;
670         args->status.num_write_errors =
671                 atomic64_read(&dev_replace->num_write_errors);
672         args->status.num_uncorrectable_read_errors =
673                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
674         switch (dev_replace->replace_state) {
675         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
676         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
677                 args->status.progress_1000 = 0;
678                 break;
679         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
680                 args->status.progress_1000 = 1000;
681                 break;
682         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
683         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
684                 srcdev = dev_replace->srcdev;
685                 args->status.progress_1000 = div_u64(dev_replace->cursor_left,
686                         div_u64(btrfs_device_get_total_bytes(srcdev), 1000));
687                 break;
688         }
689         btrfs_dev_replace_unlock(dev_replace, 0);
690 }
691
692 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
693                              struct btrfs_ioctl_dev_replace_args *args)
694 {
695         args->result = __btrfs_dev_replace_cancel(fs_info);
696         return 0;
697 }
698
699 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
700 {
701         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
702         struct btrfs_device *tgt_device = NULL;
703         struct btrfs_trans_handle *trans;
704         struct btrfs_root *root = fs_info->tree_root;
705         u64 result;
706         int ret;
707
708         if (fs_info->sb->s_flags & MS_RDONLY)
709                 return -EROFS;
710
711         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
712         btrfs_dev_replace_lock(dev_replace, 1);
713         switch (dev_replace->replace_state) {
714         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
715         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
716         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
717                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
718                 btrfs_dev_replace_unlock(dev_replace, 1);
719                 goto leave;
720         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
721         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
722                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
723                 tgt_device = dev_replace->tgtdev;
724                 dev_replace->tgtdev = NULL;
725                 dev_replace->srcdev = NULL;
726                 break;
727         }
728         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
729         dev_replace->time_stopped = get_seconds();
730         dev_replace->item_needs_writeback = 1;
731         btrfs_dev_replace_unlock(dev_replace, 1);
732         btrfs_scrub_cancel(fs_info);
733
734         trans = btrfs_start_transaction(root, 0);
735         if (IS_ERR(trans)) {
736                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
737                 return PTR_ERR(trans);
738         }
739         ret = btrfs_commit_transaction(trans, root);
740         WARN_ON(ret);
741         if (tgt_device)
742                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
743
744 leave:
745         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
746         return result;
747 }
748
749 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
750 {
751         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
752
753         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
754         btrfs_dev_replace_lock(dev_replace, 1);
755         switch (dev_replace->replace_state) {
756         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
757         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
758         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
759         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
760                 break;
761         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
762                 dev_replace->replace_state =
763                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
764                 dev_replace->time_stopped = get_seconds();
765                 dev_replace->item_needs_writeback = 1;
766                 btrfs_info(fs_info, "suspending dev_replace for unmount");
767                 break;
768         }
769
770         btrfs_dev_replace_unlock(dev_replace, 1);
771         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
772 }
773
774 /* resume dev_replace procedure that was interrupted by unmount */
775 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
776 {
777         struct task_struct *task;
778         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
779
780         btrfs_dev_replace_lock(dev_replace, 1);
781         switch (dev_replace->replace_state) {
782         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
783         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
784         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
785                 btrfs_dev_replace_unlock(dev_replace, 1);
786                 return 0;
787         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
788                 break;
789         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
790                 dev_replace->replace_state =
791                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
792                 break;
793         }
794         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
795                 btrfs_info(fs_info,
796                            "cannot continue dev_replace, tgtdev is missing");
797                 btrfs_info(fs_info,
798                            "you may cancel the operation after 'mount -o degraded'");
799                 dev_replace->replace_state =
800                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
801                 btrfs_dev_replace_unlock(dev_replace, 1);
802                 return 0;
803         }
804         btrfs_dev_replace_unlock(dev_replace, 1);
805
806         WARN_ON(atomic_xchg(
807                 &fs_info->mutually_exclusive_operation_running, 1));
808         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
809         return PTR_ERR_OR_ZERO(task);
810 }
811
812 static int btrfs_dev_replace_kthread(void *data)
813 {
814         struct btrfs_fs_info *fs_info = data;
815         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
816         struct btrfs_ioctl_dev_replace_args *status_args;
817         u64 progress;
818
819         status_args = kzalloc(sizeof(*status_args), GFP_KERNEL);
820         if (status_args) {
821                 btrfs_dev_replace_status(fs_info, status_args);
822                 progress = status_args->status.progress_1000;
823                 kfree(status_args);
824                 progress = div_u64(progress, 10);
825                 btrfs_info_in_rcu(fs_info,
826                         "continuing dev_replace from %s (devid %llu) to %s @%u%%",
827                         dev_replace->srcdev->missing ? "<missing disk>" :
828                         rcu_str_deref(dev_replace->srcdev->name),
829                         dev_replace->srcdev->devid,
830                         dev_replace->tgtdev ?
831                         rcu_str_deref(dev_replace->tgtdev->name) :
832                         "<missing target disk>",
833                         (unsigned int)progress);
834         }
835         btrfs_dev_replace_continue_on_mount(fs_info);
836         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
837
838         return 0;
839 }
840
841 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
842 {
843         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
844         int ret;
845
846         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
847                               dev_replace->committed_cursor_left,
848                               btrfs_device_get_total_bytes(dev_replace->srcdev),
849                               &dev_replace->scrub_progress, 0, 1);
850         ret = btrfs_dev_replace_finishing(fs_info, ret);
851         WARN_ON(ret);
852         return 0;
853 }
854
855 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
856 {
857         if (!dev_replace->is_valid)
858                 return 0;
859
860         switch (dev_replace->replace_state) {
861         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
862         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
863         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
864                 return 0;
865         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
866         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
867                 /*
868                  * return true even if tgtdev is missing (this is
869                  * something that can happen if the dev_replace
870                  * procedure is suspended by an umount and then
871                  * the tgtdev is missing (or "btrfs dev scan") was
872                  * not called and the the filesystem is remounted
873                  * in degraded state. This does not stop the
874                  * dev_replace procedure. It needs to be canceled
875                  * manually if the cancellation is wanted.
876                  */
877                 break;
878         }
879         return 1;
880 }
881
882 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
883 {
884         if (rw == 1) {
885                 /* write */
886 again:
887                 wait_event(dev_replace->read_lock_wq,
888                            atomic_read(&dev_replace->blocking_readers) == 0);
889                 write_lock(&dev_replace->lock);
890                 if (atomic_read(&dev_replace->blocking_readers)) {
891                         write_unlock(&dev_replace->lock);
892                         goto again;
893                 }
894         } else {
895                 read_lock(&dev_replace->lock);
896                 atomic_inc(&dev_replace->read_locks);
897         }
898 }
899
900 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
901 {
902         if (rw == 1) {
903                 /* write */
904                 ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
905                 write_unlock(&dev_replace->lock);
906         } else {
907                 ASSERT(atomic_read(&dev_replace->read_locks) > 0);
908                 atomic_dec(&dev_replace->read_locks);
909                 read_unlock(&dev_replace->lock);
910         }
911 }
912
913 /* inc blocking cnt and release read lock */
914 void btrfs_dev_replace_set_lock_blocking(
915                                         struct btrfs_dev_replace *dev_replace)
916 {
917         /* only set blocking for read lock */
918         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
919         atomic_inc(&dev_replace->blocking_readers);
920         read_unlock(&dev_replace->lock);
921 }
922
923 /* acquire read lock and dec blocking cnt */
924 void btrfs_dev_replace_clear_lock_blocking(
925                                         struct btrfs_dev_replace *dev_replace)
926 {
927         /* only set blocking for read lock */
928         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
929         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
930         read_lock(&dev_replace->lock);
931         if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
932             waitqueue_active(&dev_replace->read_lock_wq))
933                 wake_up(&dev_replace->read_lock_wq);
934 }
935
936 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
937 {
938         percpu_counter_inc(&fs_info->bio_counter);
939 }
940
941 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
942 {
943         percpu_counter_sub(&fs_info->bio_counter, amount);
944
945         if (waitqueue_active(&fs_info->replace_wait))
946                 wake_up(&fs_info->replace_wait);
947 }
948
949 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
950 {
951         while (1) {
952                 percpu_counter_inc(&fs_info->bio_counter);
953                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
954                                      &fs_info->fs_state)))
955                         break;
956
957                 btrfs_bio_counter_dec(fs_info);
958                 wait_event(fs_info->replace_wait,
959                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
960                                      &fs_info->fs_state));
961         }
962 }