ext4: force inode writes when nfsd calls commit_metadata()
[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          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
593          * update on-disk dev stats value during commit transaction
594          */
595         atomic_inc(&tgt_device->dev_stats_ccnt);
596
597         /*
598          * this is again a consistent state where no dev_replace procedure
599          * is running, the target device is part of the filesystem, the
600          * source device is not part of the filesystem anymore and its 1st
601          * superblock is scratched out so that it is no longer marked to
602          * belong to this filesystem.
603          */
604         mutex_unlock(&fs_info->chunk_mutex);
605         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
606         mutex_unlock(&uuid_mutex);
607
608         /* replace the sysfs entry */
609         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
610         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
611
612         /* write back the superblocks */
613         trans = btrfs_start_transaction(root, 0);
614         if (!IS_ERR(trans))
615                 btrfs_commit_transaction(trans);
616
617         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
618
619         return 0;
620 }
621
622 static void btrfs_dev_replace_update_device_in_mapping_tree(
623                                                 struct btrfs_fs_info *fs_info,
624                                                 struct btrfs_device *srcdev,
625                                                 struct btrfs_device *tgtdev)
626 {
627         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
628         struct extent_map *em;
629         struct map_lookup *map;
630         u64 start = 0;
631         int i;
632
633         write_lock(&em_tree->lock);
634         do {
635                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
636                 if (!em)
637                         break;
638                 map = em->map_lookup;
639                 for (i = 0; i < map->num_stripes; i++)
640                         if (srcdev == map->stripes[i].dev)
641                                 map->stripes[i].dev = tgtdev;
642                 start = em->start + em->len;
643                 free_extent_map(em);
644         } while (start);
645         write_unlock(&em_tree->lock);
646 }
647
648 /*
649  * Read progress of device replace status according to the state and last
650  * stored position. The value format is the same as for
651  * btrfs_dev_replace::progress_1000
652  */
653 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
654 {
655         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
656         u64 ret = 0;
657
658         switch (dev_replace->replace_state) {
659         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
660         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
661                 ret = 0;
662                 break;
663         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
664                 ret = 1000;
665                 break;
666         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
667         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
668                 ret = div64_u64(dev_replace->cursor_left,
669                                 div_u64(btrfs_device_get_total_bytes(
670                                                 dev_replace->srcdev), 1000));
671                 break;
672         }
673
674         return ret;
675 }
676
677 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
678                               struct btrfs_ioctl_dev_replace_args *args)
679 {
680         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
681
682         btrfs_dev_replace_lock(dev_replace, 0);
683         /* even if !dev_replace_is_valid, the values are good enough for
684          * the replace_status ioctl */
685         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
686         args->status.replace_state = dev_replace->replace_state;
687         args->status.time_started = dev_replace->time_started;
688         args->status.time_stopped = dev_replace->time_stopped;
689         args->status.num_write_errors =
690                 atomic64_read(&dev_replace->num_write_errors);
691         args->status.num_uncorrectable_read_errors =
692                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
693         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
694         btrfs_dev_replace_unlock(dev_replace, 0);
695 }
696
697 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
698                              struct btrfs_ioctl_dev_replace_args *args)
699 {
700         args->result = __btrfs_dev_replace_cancel(fs_info);
701         return 0;
702 }
703
704 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
705 {
706         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
707         struct btrfs_device *tgt_device = NULL;
708         struct btrfs_trans_handle *trans;
709         struct btrfs_root *root = fs_info->tree_root;
710         u64 result;
711         int ret;
712
713         if (sb_rdonly(fs_info->sb))
714                 return -EROFS;
715
716         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
717         btrfs_dev_replace_lock(dev_replace, 1);
718         switch (dev_replace->replace_state) {
719         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
720         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
721         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
722                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
723                 btrfs_dev_replace_unlock(dev_replace, 1);
724                 goto leave;
725         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
726         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
727                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
728                 tgt_device = dev_replace->tgtdev;
729                 dev_replace->tgtdev = NULL;
730                 dev_replace->srcdev = NULL;
731                 break;
732         }
733         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
734         dev_replace->time_stopped = get_seconds();
735         dev_replace->item_needs_writeback = 1;
736         btrfs_dev_replace_unlock(dev_replace, 1);
737         btrfs_scrub_cancel(fs_info);
738
739         trans = btrfs_start_transaction(root, 0);
740         if (IS_ERR(trans)) {
741                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
742                 return PTR_ERR(trans);
743         }
744         ret = btrfs_commit_transaction(trans);
745         WARN_ON(ret);
746         if (tgt_device)
747                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
748
749 leave:
750         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
751         return result;
752 }
753
754 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
755 {
756         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
757
758         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
759         btrfs_dev_replace_lock(dev_replace, 1);
760         switch (dev_replace->replace_state) {
761         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
762         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
763         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
764         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
765                 break;
766         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
767                 dev_replace->replace_state =
768                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
769                 dev_replace->time_stopped = get_seconds();
770                 dev_replace->item_needs_writeback = 1;
771                 btrfs_info(fs_info, "suspending dev_replace for unmount");
772                 break;
773         }
774
775         btrfs_dev_replace_unlock(dev_replace, 1);
776         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
777 }
778
779 /* resume dev_replace procedure that was interrupted by unmount */
780 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
781 {
782         struct task_struct *task;
783         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
784
785         btrfs_dev_replace_lock(dev_replace, 1);
786         switch (dev_replace->replace_state) {
787         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
788         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
789         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
790                 btrfs_dev_replace_unlock(dev_replace, 1);
791                 return 0;
792         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
793                 break;
794         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
795                 dev_replace->replace_state =
796                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
797                 break;
798         }
799         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
800                 btrfs_info(fs_info,
801                            "cannot continue dev_replace, tgtdev is missing");
802                 btrfs_info(fs_info,
803                            "you may cancel the operation after 'mount -o degraded'");
804                 btrfs_dev_replace_unlock(dev_replace, 1);
805                 return 0;
806         }
807         btrfs_dev_replace_unlock(dev_replace, 1);
808
809         WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
810         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
811         return PTR_ERR_OR_ZERO(task);
812 }
813
814 static int btrfs_dev_replace_kthread(void *data)
815 {
816         struct btrfs_fs_info *fs_info = data;
817         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
818         u64 progress;
819
820         progress = btrfs_dev_replace_progress(fs_info);
821         progress = div_u64(progress, 10);
822         btrfs_info_in_rcu(fs_info,
823                 "continuing dev_replace from %s (devid %llu) to %s @%u%%",
824                 dev_replace->srcdev->missing ? "<missing disk>"
825                         : rcu_str_deref(dev_replace->srcdev->name),
826                 dev_replace->srcdev->devid,
827                 dev_replace->tgtdev ? rcu_str_deref(dev_replace->tgtdev->name)
828                         : "<missing target disk>",
829                 (unsigned int)progress);
830
831         btrfs_dev_replace_continue_on_mount(fs_info);
832         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
833
834         return 0;
835 }
836
837 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
838 {
839         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
840         int ret;
841
842         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
843                               dev_replace->committed_cursor_left,
844                               btrfs_device_get_total_bytes(dev_replace->srcdev),
845                               &dev_replace->scrub_progress, 0, 1);
846         ret = btrfs_dev_replace_finishing(fs_info, ret);
847         WARN_ON(ret);
848         return 0;
849 }
850
851 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
852 {
853         if (!dev_replace->is_valid)
854                 return 0;
855
856         switch (dev_replace->replace_state) {
857         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
858         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
859         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
860                 return 0;
861         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
862         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
863                 /*
864                  * return true even if tgtdev is missing (this is
865                  * something that can happen if the dev_replace
866                  * procedure is suspended by an umount and then
867                  * the tgtdev is missing (or "btrfs dev scan") was
868                  * not called and the the filesystem is remounted
869                  * in degraded state. This does not stop the
870                  * dev_replace procedure. It needs to be canceled
871                  * manually if the cancellation is wanted.
872                  */
873                 break;
874         }
875         return 1;
876 }
877
878 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
879 {
880         if (rw == 1) {
881                 /* write */
882 again:
883                 wait_event(dev_replace->read_lock_wq,
884                            atomic_read(&dev_replace->blocking_readers) == 0);
885                 write_lock(&dev_replace->lock);
886                 if (atomic_read(&dev_replace->blocking_readers)) {
887                         write_unlock(&dev_replace->lock);
888                         goto again;
889                 }
890         } else {
891                 read_lock(&dev_replace->lock);
892                 atomic_inc(&dev_replace->read_locks);
893         }
894 }
895
896 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
897 {
898         if (rw == 1) {
899                 /* write */
900                 ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
901                 write_unlock(&dev_replace->lock);
902         } else {
903                 ASSERT(atomic_read(&dev_replace->read_locks) > 0);
904                 atomic_dec(&dev_replace->read_locks);
905                 read_unlock(&dev_replace->lock);
906         }
907 }
908
909 /* inc blocking cnt and release read lock */
910 void btrfs_dev_replace_set_lock_blocking(
911                                         struct btrfs_dev_replace *dev_replace)
912 {
913         /* only set blocking for read lock */
914         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
915         atomic_inc(&dev_replace->blocking_readers);
916         read_unlock(&dev_replace->lock);
917 }
918
919 /* acquire read lock and dec blocking cnt */
920 void btrfs_dev_replace_clear_lock_blocking(
921                                         struct btrfs_dev_replace *dev_replace)
922 {
923         /* only set blocking for read lock */
924         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
925         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
926         read_lock(&dev_replace->lock);
927         if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
928             waitqueue_active(&dev_replace->read_lock_wq))
929                 wake_up(&dev_replace->read_lock_wq);
930 }
931
932 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
933 {
934         percpu_counter_inc(&fs_info->bio_counter);
935 }
936
937 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
938 {
939         percpu_counter_sub(&fs_info->bio_counter, amount);
940
941         if (waitqueue_active(&fs_info->replace_wait))
942                 wake_up(&fs_info->replace_wait);
943 }
944
945 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
946 {
947         while (1) {
948                 percpu_counter_inc(&fs_info->bio_counter);
949                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
950                                      &fs_info->fs_state)))
951                         break;
952
953                 btrfs_bio_counter_dec(fs_info);
954                 wait_event(fs_info->replace_wait,
955                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
956                                      &fs_info->fs_state));
957         }
958 }