bee3edeea7a37404de4d428a57e90c6bbcac6bc1
[platform/kernel/linux-exynos.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(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(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_fs_info *fs_info,
308                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
309                 int read_src)
310 {
311         struct btrfs_root *root = fs_info->dev_root;
312         struct btrfs_trans_handle *trans;
313         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
314         int ret;
315         struct btrfs_device *tgt_device = NULL;
316         struct btrfs_device *src_device = NULL;
317
318         /* the disk copy procedure reuses the scrub code */
319         mutex_lock(&fs_info->volume_mutex);
320         ret = btrfs_find_device_by_devspec(fs_info, srcdevid,
321                                             srcdev_name, &src_device);
322         if (ret) {
323                 mutex_unlock(&fs_info->volume_mutex);
324                 return ret;
325         }
326
327         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
328                                             src_device, &tgt_device);
329         mutex_unlock(&fs_info->volume_mutex);
330         if (ret)
331                 return ret;
332
333         /*
334          * Here we commit the transaction to make sure commit_total_bytes
335          * of all the devices are updated.
336          */
337         trans = btrfs_attach_transaction(root);
338         if (!IS_ERR(trans)) {
339                 ret = btrfs_commit_transaction(trans);
340                 if (ret)
341                         return ret;
342         } else if (PTR_ERR(trans) != -ENOENT) {
343                 return PTR_ERR(trans);
344         }
345
346         btrfs_dev_replace_lock(dev_replace, 1);
347         switch (dev_replace->replace_state) {
348         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
349         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
350         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
351                 break;
352         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
353         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
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(fs_info, U64_MAX, 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                 goto leave;
399         }
400
401         ret = btrfs_commit_transaction(trans);
402         WARN_ON(ret);
403
404         /* the disk copy procedure reuses the scrub code */
405         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
406                               btrfs_device_get_total_bytes(src_device),
407                               &dev_replace->scrub_progress, 0, 1);
408
409         ret = btrfs_dev_replace_finishing(fs_info, ret);
410         if (ret == -EINPROGRESS) {
411                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
412         } else {
413                 WARN_ON(ret);
414         }
415
416         return ret;
417
418 leave:
419         dev_replace->srcdev = NULL;
420         dev_replace->tgtdev = NULL;
421         btrfs_dev_replace_unlock(dev_replace, 1);
422         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
423         return ret;
424 }
425
426 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
427                             struct btrfs_ioctl_dev_replace_args *args)
428 {
429         int ret;
430
431         switch (args->start.cont_reading_from_srcdev_mode) {
432         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
433         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
434                 break;
435         default:
436                 return -EINVAL;
437         }
438
439         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
440             args->start.tgtdev_name[0] == '\0')
441                 return -EINVAL;
442
443         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
444                                         args->start.srcdevid,
445                                         args->start.srcdev_name,
446                                         args->start.cont_reading_from_srcdev_mode);
447         args->result = ret;
448         /* don't warn if EINPROGRESS, someone else might be running scrub */
449         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
450                 ret = 0;
451
452         return ret;
453 }
454
455 /*
456  * blocked until all in-flight bios operations are finished.
457  */
458 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
459 {
460         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
461         wait_event(fs_info->replace_wait, !percpu_counter_sum(
462                    &fs_info->bio_counter));
463 }
464
465 /*
466  * we have removed target device, it is safe to allow new bios request.
467  */
468 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
469 {
470         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
471         wake_up(&fs_info->replace_wait);
472 }
473
474 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
475                                        int scrub_ret)
476 {
477         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
478         struct btrfs_device *tgt_device;
479         struct btrfs_device *src_device;
480         struct btrfs_root *root = fs_info->tree_root;
481         u8 uuid_tmp[BTRFS_UUID_SIZE];
482         struct btrfs_trans_handle *trans;
483         int ret = 0;
484
485         /* don't allow cancel or unmount to disturb the finishing procedure */
486         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
487
488         btrfs_dev_replace_lock(dev_replace, 0);
489         /* was the operation canceled, or is it finished? */
490         if (dev_replace->replace_state !=
491             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
492                 btrfs_dev_replace_unlock(dev_replace, 0);
493                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
494                 return 0;
495         }
496
497         tgt_device = dev_replace->tgtdev;
498         src_device = dev_replace->srcdev;
499         btrfs_dev_replace_unlock(dev_replace, 0);
500
501         /*
502          * flush all outstanding I/O and inode extent mappings before the
503          * copy operation is declared as being finished
504          */
505         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
506         if (ret) {
507                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
508                 return ret;
509         }
510         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
511
512         trans = btrfs_start_transaction(root, 0);
513         if (IS_ERR(trans)) {
514                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
515                 return PTR_ERR(trans);
516         }
517         ret = btrfs_commit_transaction(trans);
518         WARN_ON(ret);
519
520         mutex_lock(&uuid_mutex);
521         /* keep away write_all_supers() during the finishing procedure */
522         mutex_lock(&fs_info->fs_devices->device_list_mutex);
523         mutex_lock(&fs_info->chunk_mutex);
524         btrfs_dev_replace_lock(dev_replace, 1);
525         dev_replace->replace_state =
526                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
527                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
528         dev_replace->tgtdev = NULL;
529         dev_replace->srcdev = NULL;
530         dev_replace->time_stopped = get_seconds();
531         dev_replace->item_needs_writeback = 1;
532
533         /* replace old device with new one in mapping tree */
534         if (!scrub_ret) {
535                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
536                                                                 src_device,
537                                                                 tgt_device);
538         } else {
539                 btrfs_err_in_rcu(fs_info,
540                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
541                                  src_device->missing ? "<missing disk>" :
542                                  rcu_str_deref(src_device->name),
543                                  src_device->devid,
544                                  rcu_str_deref(tgt_device->name), scrub_ret);
545                 btrfs_dev_replace_unlock(dev_replace, 1);
546                 mutex_unlock(&fs_info->chunk_mutex);
547                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
548                 mutex_unlock(&uuid_mutex);
549                 btrfs_rm_dev_replace_blocked(fs_info);
550                 if (tgt_device)
551                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
552                 btrfs_rm_dev_replace_unblocked(fs_info);
553                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
554
555                 return scrub_ret;
556         }
557
558         btrfs_info_in_rcu(fs_info,
559                           "dev_replace from %s (devid %llu) to %s finished",
560                           src_device->missing ? "<missing disk>" :
561                           rcu_str_deref(src_device->name),
562                           src_device->devid,
563                           rcu_str_deref(tgt_device->name));
564         tgt_device->is_tgtdev_for_dev_replace = 0;
565         tgt_device->devid = src_device->devid;
566         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
567         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
568         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
569         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
570         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
571         btrfs_device_set_disk_total_bytes(tgt_device,
572                                           src_device->disk_total_bytes);
573         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
574         ASSERT(list_empty(&src_device->resized_list));
575         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
576         tgt_device->commit_bytes_used = src_device->bytes_used;
577
578         btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
579
580         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
581         fs_info->fs_devices->rw_devices++;
582
583         btrfs_dev_replace_unlock(dev_replace, 1);
584
585         btrfs_rm_dev_replace_blocked(fs_info);
586
587         btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
588
589         btrfs_rm_dev_replace_unblocked(fs_info);
590
591         /*
592          * this is again a consistent state where no dev_replace procedure
593          * is running, the target device is part of the filesystem, the
594          * source device is not part of the filesystem anymore and its 1st
595          * superblock is scratched out so that it is no longer marked to
596          * belong to this filesystem.
597          */
598         mutex_unlock(&fs_info->chunk_mutex);
599         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
600         mutex_unlock(&uuid_mutex);
601
602         /* replace the sysfs entry */
603         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
604         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
605
606         /* write back the superblocks */
607         trans = btrfs_start_transaction(root, 0);
608         if (!IS_ERR(trans))
609                 btrfs_commit_transaction(trans);
610
611         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
612
613         return 0;
614 }
615
616 static void btrfs_dev_replace_update_device_in_mapping_tree(
617                                                 struct btrfs_fs_info *fs_info,
618                                                 struct btrfs_device *srcdev,
619                                                 struct btrfs_device *tgtdev)
620 {
621         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
622         struct extent_map *em;
623         struct map_lookup *map;
624         u64 start = 0;
625         int i;
626
627         write_lock(&em_tree->lock);
628         do {
629                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
630                 if (!em)
631                         break;
632                 map = em->map_lookup;
633                 for (i = 0; i < map->num_stripes; i++)
634                         if (srcdev == map->stripes[i].dev)
635                                 map->stripes[i].dev = tgtdev;
636                 start = em->start + em->len;
637                 free_extent_map(em);
638         } while (start);
639         write_unlock(&em_tree->lock);
640 }
641
642 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
643                               struct btrfs_ioctl_dev_replace_args *args)
644 {
645         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
646         struct btrfs_device *srcdev;
647
648         btrfs_dev_replace_lock(dev_replace, 0);
649         /* even if !dev_replace_is_valid, the values are good enough for
650          * the replace_status ioctl */
651         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
652         args->status.replace_state = dev_replace->replace_state;
653         args->status.time_started = dev_replace->time_started;
654         args->status.time_stopped = dev_replace->time_stopped;
655         args->status.num_write_errors =
656                 atomic64_read(&dev_replace->num_write_errors);
657         args->status.num_uncorrectable_read_errors =
658                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
659         switch (dev_replace->replace_state) {
660         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
661         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
662                 args->status.progress_1000 = 0;
663                 break;
664         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
665                 args->status.progress_1000 = 1000;
666                 break;
667         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
668         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
669                 srcdev = dev_replace->srcdev;
670                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
671                         div_u64(btrfs_device_get_total_bytes(srcdev), 1000));
672                 break;
673         }
674         btrfs_dev_replace_unlock(dev_replace, 0);
675 }
676
677 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
678                              struct btrfs_ioctl_dev_replace_args *args)
679 {
680         args->result = __btrfs_dev_replace_cancel(fs_info);
681         return 0;
682 }
683
684 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
685 {
686         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
687         struct btrfs_device *tgt_device = NULL;
688         struct btrfs_trans_handle *trans;
689         struct btrfs_root *root = fs_info->tree_root;
690         u64 result;
691         int ret;
692
693         if (fs_info->sb->s_flags & MS_RDONLY)
694                 return -EROFS;
695
696         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
697         btrfs_dev_replace_lock(dev_replace, 1);
698         switch (dev_replace->replace_state) {
699         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
700         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
701         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
702                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
703                 btrfs_dev_replace_unlock(dev_replace, 1);
704                 goto leave;
705         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
706         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
707                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
708                 tgt_device = dev_replace->tgtdev;
709                 dev_replace->tgtdev = NULL;
710                 dev_replace->srcdev = NULL;
711                 break;
712         }
713         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
714         dev_replace->time_stopped = get_seconds();
715         dev_replace->item_needs_writeback = 1;
716         btrfs_dev_replace_unlock(dev_replace, 1);
717         btrfs_scrub_cancel(fs_info);
718
719         trans = btrfs_start_transaction(root, 0);
720         if (IS_ERR(trans)) {
721                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
722                 return PTR_ERR(trans);
723         }
724         ret = btrfs_commit_transaction(trans);
725         WARN_ON(ret);
726         if (tgt_device)
727                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
728
729 leave:
730         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
731         return result;
732 }
733
734 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
735 {
736         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
737
738         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
739         btrfs_dev_replace_lock(dev_replace, 1);
740         switch (dev_replace->replace_state) {
741         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
742         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
743         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
744         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
745                 break;
746         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
747                 dev_replace->replace_state =
748                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
749                 dev_replace->time_stopped = get_seconds();
750                 dev_replace->item_needs_writeback = 1;
751                 btrfs_info(fs_info, "suspending dev_replace for unmount");
752                 break;
753         }
754
755         btrfs_dev_replace_unlock(dev_replace, 1);
756         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
757 }
758
759 /* resume dev_replace procedure that was interrupted by unmount */
760 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
761 {
762         struct task_struct *task;
763         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
764
765         btrfs_dev_replace_lock(dev_replace, 1);
766         switch (dev_replace->replace_state) {
767         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
768         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
769         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
770                 btrfs_dev_replace_unlock(dev_replace, 1);
771                 return 0;
772         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
773                 break;
774         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
775                 dev_replace->replace_state =
776                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
777                 break;
778         }
779         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
780                 btrfs_info(fs_info,
781                            "cannot continue dev_replace, tgtdev is missing");
782                 btrfs_info(fs_info,
783                            "you may cancel the operation after 'mount -o degraded'");
784                 btrfs_dev_replace_unlock(dev_replace, 1);
785                 return 0;
786         }
787         btrfs_dev_replace_unlock(dev_replace, 1);
788
789         WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
790         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
791         return PTR_ERR_OR_ZERO(task);
792 }
793
794 static int btrfs_dev_replace_kthread(void *data)
795 {
796         struct btrfs_fs_info *fs_info = data;
797         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
798         struct btrfs_ioctl_dev_replace_args *status_args;
799         u64 progress;
800
801         status_args = kzalloc(sizeof(*status_args), GFP_KERNEL);
802         if (status_args) {
803                 btrfs_dev_replace_status(fs_info, status_args);
804                 progress = status_args->status.progress_1000;
805                 kfree(status_args);
806                 progress = div_u64(progress, 10);
807                 btrfs_info_in_rcu(fs_info,
808                         "continuing dev_replace from %s (devid %llu) to %s @%u%%",
809                         dev_replace->srcdev->missing ? "<missing disk>" :
810                         rcu_str_deref(dev_replace->srcdev->name),
811                         dev_replace->srcdev->devid,
812                         dev_replace->tgtdev ?
813                         rcu_str_deref(dev_replace->tgtdev->name) :
814                         "<missing target disk>",
815                         (unsigned int)progress);
816         }
817         btrfs_dev_replace_continue_on_mount(fs_info);
818         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
819
820         return 0;
821 }
822
823 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
824 {
825         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
826         int ret;
827
828         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
829                               dev_replace->committed_cursor_left,
830                               btrfs_device_get_total_bytes(dev_replace->srcdev),
831                               &dev_replace->scrub_progress, 0, 1);
832         ret = btrfs_dev_replace_finishing(fs_info, ret);
833         WARN_ON(ret);
834         return 0;
835 }
836
837 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
838 {
839         if (!dev_replace->is_valid)
840                 return 0;
841
842         switch (dev_replace->replace_state) {
843         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
844         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
845         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
846                 return 0;
847         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
848         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
849                 /*
850                  * return true even if tgtdev is missing (this is
851                  * something that can happen if the dev_replace
852                  * procedure is suspended by an umount and then
853                  * the tgtdev is missing (or "btrfs dev scan") was
854                  * not called and the the filesystem is remounted
855                  * in degraded state. This does not stop the
856                  * dev_replace procedure. It needs to be canceled
857                  * manually if the cancellation is wanted.
858                  */
859                 break;
860         }
861         return 1;
862 }
863
864 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
865 {
866         if (rw == 1) {
867                 /* write */
868 again:
869                 wait_event(dev_replace->read_lock_wq,
870                            atomic_read(&dev_replace->blocking_readers) == 0);
871                 write_lock(&dev_replace->lock);
872                 if (atomic_read(&dev_replace->blocking_readers)) {
873                         write_unlock(&dev_replace->lock);
874                         goto again;
875                 }
876         } else {
877                 read_lock(&dev_replace->lock);
878                 atomic_inc(&dev_replace->read_locks);
879         }
880 }
881
882 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
883 {
884         if (rw == 1) {
885                 /* write */
886                 ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
887                 write_unlock(&dev_replace->lock);
888         } else {
889                 ASSERT(atomic_read(&dev_replace->read_locks) > 0);
890                 atomic_dec(&dev_replace->read_locks);
891                 read_unlock(&dev_replace->lock);
892         }
893 }
894
895 /* inc blocking cnt and release read lock */
896 void btrfs_dev_replace_set_lock_blocking(
897                                         struct btrfs_dev_replace *dev_replace)
898 {
899         /* only set blocking for read lock */
900         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
901         atomic_inc(&dev_replace->blocking_readers);
902         read_unlock(&dev_replace->lock);
903 }
904
905 /* acquire read lock and dec blocking cnt */
906 void btrfs_dev_replace_clear_lock_blocking(
907                                         struct btrfs_dev_replace *dev_replace)
908 {
909         /* only set blocking for read lock */
910         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
911         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
912         read_lock(&dev_replace->lock);
913         if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
914             waitqueue_active(&dev_replace->read_lock_wq))
915                 wake_up(&dev_replace->read_lock_wq);
916 }
917
918 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
919 {
920         percpu_counter_inc(&fs_info->bio_counter);
921 }
922
923 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
924 {
925         percpu_counter_sub(&fs_info->bio_counter, amount);
926
927         if (waitqueue_active(&fs_info->replace_wait))
928                 wake_up(&fs_info->replace_wait);
929 }
930
931 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
932 {
933         while (1) {
934                 percpu_counter_inc(&fs_info->bio_counter);
935                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
936                                      &fs_info->fs_state)))
937                         break;
938
939                 btrfs_bio_counter_dec(fs_info);
940                 wait_event(fs_info->replace_wait,
941                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
942                                      &fs_info->fs_state));
943         }
944 }