Merge branches 'x86-ras-for-linus', 'x86-uv-for-linus' and 'x86-vdso-for-linus' of...
[cascardo/linux.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 int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
48                                          char *srcdev_name,
49                                          struct btrfs_device **device);
50 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info);
51 static int btrfs_dev_replace_kthread(void *data);
52 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
53
54
55 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
56 {
57         struct btrfs_key key;
58         struct btrfs_root *dev_root = fs_info->dev_root;
59         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
60         struct extent_buffer *eb;
61         int slot;
62         int ret = 0;
63         struct btrfs_path *path = NULL;
64         int item_size;
65         struct btrfs_dev_replace_item *ptr;
66         u64 src_devid;
67
68         path = btrfs_alloc_path();
69         if (!path) {
70                 ret = -ENOMEM;
71                 goto out;
72         }
73
74         key.objectid = 0;
75         key.type = BTRFS_DEV_REPLACE_KEY;
76         key.offset = 0;
77         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
78         if (ret) {
79 no_valid_dev_replace_entry_found:
80                 ret = 0;
81                 dev_replace->replace_state =
82                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
83                 dev_replace->cont_reading_from_srcdev_mode =
84                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
85                 dev_replace->replace_state = 0;
86                 dev_replace->time_started = 0;
87                 dev_replace->time_stopped = 0;
88                 atomic64_set(&dev_replace->num_write_errors, 0);
89                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
90                 dev_replace->cursor_left = 0;
91                 dev_replace->committed_cursor_left = 0;
92                 dev_replace->cursor_left_last_write_of_item = 0;
93                 dev_replace->cursor_right = 0;
94                 dev_replace->srcdev = NULL;
95                 dev_replace->tgtdev = NULL;
96                 dev_replace->is_valid = 0;
97                 dev_replace->item_needs_writeback = 0;
98                 goto out;
99         }
100         slot = path->slots[0];
101         eb = path->nodes[0];
102         item_size = btrfs_item_size_nr(eb, slot);
103         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
104
105         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
106                 btrfs_warn(fs_info,
107                         "dev_replace entry found has unexpected size, ignore entry");
108                 goto no_valid_dev_replace_entry_found;
109         }
110
111         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
112         dev_replace->cont_reading_from_srcdev_mode =
113                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
114         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
115         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
116         dev_replace->time_stopped =
117                 btrfs_dev_replace_time_stopped(eb, ptr);
118         atomic64_set(&dev_replace->num_write_errors,
119                      btrfs_dev_replace_num_write_errors(eb, ptr));
120         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
121                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
122         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
123         dev_replace->committed_cursor_left = dev_replace->cursor_left;
124         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
125         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
126         dev_replace->is_valid = 1;
127
128         dev_replace->item_needs_writeback = 0;
129         switch (dev_replace->replace_state) {
130         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
131         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
132         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
133                 dev_replace->srcdev = NULL;
134                 dev_replace->tgtdev = NULL;
135                 break;
136         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
137         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
138                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
139                                                         NULL, NULL);
140                 dev_replace->tgtdev = btrfs_find_device(fs_info,
141                                                         BTRFS_DEV_REPLACE_DEVID,
142                                                         NULL, NULL);
143                 /*
144                  * allow 'btrfs dev replace_cancel' if src/tgt device is
145                  * missing
146                  */
147                 if (!dev_replace->srcdev &&
148                     !btrfs_test_opt(dev_root, DEGRADED)) {
149                         ret = -EIO;
150                         btrfs_warn(fs_info,
151                            "cannot mount because device replace operation is ongoing and");
152                         btrfs_warn(fs_info,
153                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
154                            src_devid);
155                 }
156                 if (!dev_replace->tgtdev &&
157                     !btrfs_test_opt(dev_root, DEGRADED)) {
158                         ret = -EIO;
159                         btrfs_warn(fs_info,
160                            "cannot mount because device replace operation is ongoing and");
161                         btrfs_warn(fs_info,
162                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
163                                 BTRFS_DEV_REPLACE_DEVID);
164                 }
165                 if (dev_replace->tgtdev) {
166                         if (dev_replace->srcdev) {
167                                 dev_replace->tgtdev->total_bytes =
168                                         dev_replace->srcdev->total_bytes;
169                                 dev_replace->tgtdev->disk_total_bytes =
170                                         dev_replace->srcdev->disk_total_bytes;
171                                 dev_replace->tgtdev->commit_total_bytes =
172                                         dev_replace->srcdev->commit_total_bytes;
173                                 dev_replace->tgtdev->bytes_used =
174                                         dev_replace->srcdev->bytes_used;
175                                 dev_replace->tgtdev->commit_bytes_used =
176                                         dev_replace->srcdev->commit_bytes_used;
177                         }
178                         dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
179                         btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
180                                 dev_replace->tgtdev);
181                 }
182                 break;
183         }
184
185 out:
186         if (path)
187                 btrfs_free_path(path);
188         return ret;
189 }
190
191 /*
192  * called from commit_transaction. Writes changed device replace state to
193  * disk.
194  */
195 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
196                           struct btrfs_fs_info *fs_info)
197 {
198         int ret;
199         struct btrfs_root *dev_root = fs_info->dev_root;
200         struct btrfs_path *path;
201         struct btrfs_key key;
202         struct extent_buffer *eb;
203         struct btrfs_dev_replace_item *ptr;
204         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
205
206         btrfs_dev_replace_lock(dev_replace);
207         if (!dev_replace->is_valid ||
208             !dev_replace->item_needs_writeback) {
209                 btrfs_dev_replace_unlock(dev_replace);
210                 return 0;
211         }
212         btrfs_dev_replace_unlock(dev_replace);
213
214         key.objectid = 0;
215         key.type = BTRFS_DEV_REPLACE_KEY;
216         key.offset = 0;
217
218         path = btrfs_alloc_path();
219         if (!path) {
220                 ret = -ENOMEM;
221                 goto out;
222         }
223         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
224         if (ret < 0) {
225                 btrfs_warn(fs_info, "error %d while searching for dev_replace item!",
226                         ret);
227                 goto out;
228         }
229
230         if (ret == 0 &&
231             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
232                 /*
233                  * need to delete old one and insert a new one.
234                  * Since no attempt is made to recover any old state, if the
235                  * dev_replace state is 'running', the data on the target
236                  * drive is lost.
237                  * It would be possible to recover the state: just make sure
238                  * that the beginning of the item is never changed and always
239                  * contains all the essential information. Then read this
240                  * minimal set of information and use it as a base for the
241                  * new state.
242                  */
243                 ret = btrfs_del_item(trans, dev_root, path);
244                 if (ret != 0) {
245                         btrfs_warn(fs_info, "delete too small dev_replace item failed %d!",
246                                 ret);
247                         goto out;
248                 }
249                 ret = 1;
250         }
251
252         if (ret == 1) {
253                 /* need to insert a new item */
254                 btrfs_release_path(path);
255                 ret = btrfs_insert_empty_item(trans, dev_root, path,
256                                               &key, sizeof(*ptr));
257                 if (ret < 0) {
258                         btrfs_warn(fs_info, "insert dev_replace item failed %d!",
259                                 ret);
260                         goto out;
261                 }
262         }
263
264         eb = path->nodes[0];
265         ptr = btrfs_item_ptr(eb, path->slots[0],
266                              struct btrfs_dev_replace_item);
267
268         btrfs_dev_replace_lock(dev_replace);
269         if (dev_replace->srcdev)
270                 btrfs_set_dev_replace_src_devid(eb, ptr,
271                         dev_replace->srcdev->devid);
272         else
273                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
274         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
275                 dev_replace->cont_reading_from_srcdev_mode);
276         btrfs_set_dev_replace_replace_state(eb, ptr,
277                 dev_replace->replace_state);
278         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
279         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
280         btrfs_set_dev_replace_num_write_errors(eb, ptr,
281                 atomic64_read(&dev_replace->num_write_errors));
282         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
283                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
284         dev_replace->cursor_left_last_write_of_item =
285                 dev_replace->cursor_left;
286         btrfs_set_dev_replace_cursor_left(eb, ptr,
287                 dev_replace->cursor_left_last_write_of_item);
288         btrfs_set_dev_replace_cursor_right(eb, ptr,
289                 dev_replace->cursor_right);
290         dev_replace->item_needs_writeback = 0;
291         btrfs_dev_replace_unlock(dev_replace);
292
293         btrfs_mark_buffer_dirty(eb);
294
295 out:
296         btrfs_free_path(path);
297
298         return ret;
299 }
300
301 void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
302 {
303         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
304
305         dev_replace->committed_cursor_left =
306                 dev_replace->cursor_left_last_write_of_item;
307 }
308
309 int btrfs_dev_replace_start(struct btrfs_root *root,
310                             struct btrfs_ioctl_dev_replace_args *args)
311 {
312         struct btrfs_trans_handle *trans;
313         struct btrfs_fs_info *fs_info = root->fs_info;
314         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
315         int ret;
316         struct btrfs_device *tgt_device = NULL;
317         struct btrfs_device *src_device = NULL;
318
319         if (btrfs_fs_incompat(fs_info, RAID56)) {
320                 btrfs_warn(fs_info, "dev_replace cannot yet handle RAID5/RAID6");
321                 return -EOPNOTSUPP;
322         }
323
324         switch (args->start.cont_reading_from_srcdev_mode) {
325         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
326         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
327                 break;
328         default:
329                 return -EINVAL;
330         }
331
332         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
333             args->start.tgtdev_name[0] == '\0')
334                 return -EINVAL;
335
336         /*
337          * Here we commit the transaction to make sure commit_total_bytes
338          * of all the devices are updated.
339          */
340         trans = btrfs_attach_transaction(root);
341         if (!IS_ERR(trans)) {
342                 ret = btrfs_commit_transaction(trans, root);
343                 if (ret)
344                         return ret;
345         } else if (PTR_ERR(trans) != -ENOENT) {
346                 return PTR_ERR(trans);
347         }
348
349         /* the disk copy procedure reuses the scrub code */
350         mutex_lock(&fs_info->volume_mutex);
351         ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
352                                             args->start.srcdev_name,
353                                             &src_device);
354         if (ret) {
355                 mutex_unlock(&fs_info->volume_mutex);
356                 return ret;
357         }
358
359         ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
360                                             src_device, &tgt_device);
361         mutex_unlock(&fs_info->volume_mutex);
362         if (ret)
363                 return ret;
364
365         btrfs_dev_replace_lock(dev_replace);
366         switch (dev_replace->replace_state) {
367         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
368         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
369         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
370                 break;
371         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
372         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
373                 args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
374                 goto leave;
375         }
376
377         dev_replace->cont_reading_from_srcdev_mode =
378                 args->start.cont_reading_from_srcdev_mode;
379         WARN_ON(!src_device);
380         dev_replace->srcdev = src_device;
381         WARN_ON(!tgt_device);
382         dev_replace->tgtdev = tgt_device;
383
384         printk_in_rcu(KERN_INFO
385                       "BTRFS: dev_replace from %s (devid %llu) to %s started\n",
386                       src_device->missing ? "<missing disk>" :
387                         rcu_str_deref(src_device->name),
388                       src_device->devid,
389                       rcu_str_deref(tgt_device->name));
390
391         /*
392          * from now on, the writes to the srcdev are all duplicated to
393          * go to the tgtdev as well (refer to btrfs_map_block()).
394          */
395         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
396         dev_replace->time_started = get_seconds();
397         dev_replace->cursor_left = 0;
398         dev_replace->committed_cursor_left = 0;
399         dev_replace->cursor_left_last_write_of_item = 0;
400         dev_replace->cursor_right = 0;
401         dev_replace->is_valid = 1;
402         dev_replace->item_needs_writeback = 1;
403         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
404         btrfs_dev_replace_unlock(dev_replace);
405
406         btrfs_wait_ordered_roots(root->fs_info, -1);
407
408         /* force writing the updated state information to disk */
409         trans = btrfs_start_transaction(root, 0);
410         if (IS_ERR(trans)) {
411                 ret = PTR_ERR(trans);
412                 btrfs_dev_replace_lock(dev_replace);
413                 goto leave;
414         }
415
416         ret = btrfs_commit_transaction(trans, root);
417         WARN_ON(ret);
418
419         /* the disk copy procedure reuses the scrub code */
420         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
421                               btrfs_device_get_total_bytes(src_device),
422                               &dev_replace->scrub_progress, 0, 1);
423
424         ret = btrfs_dev_replace_finishing(root->fs_info, ret);
425         WARN_ON(ret);
426
427         return 0;
428
429 leave:
430         dev_replace->srcdev = NULL;
431         dev_replace->tgtdev = NULL;
432         btrfs_dev_replace_unlock(dev_replace);
433         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
434         return ret;
435 }
436
437 /*
438  * blocked until all flighting bios are finished.
439  */
440 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
441 {
442         s64 writers;
443         DEFINE_WAIT(wait);
444
445         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
446         do {
447                 prepare_to_wait(&fs_info->replace_wait, &wait,
448                                 TASK_UNINTERRUPTIBLE);
449                 writers = percpu_counter_sum(&fs_info->bio_counter);
450                 if (writers)
451                         schedule();
452                 finish_wait(&fs_info->replace_wait, &wait);
453         } while (writers);
454 }
455
456 /*
457  * we have removed target device, it is safe to allow new bios request.
458  */
459 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
460 {
461         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
462         if (waitqueue_active(&fs_info->replace_wait))
463                 wake_up(&fs_info->replace_wait);
464 }
465
466 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
467                                        int scrub_ret)
468 {
469         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
470         struct btrfs_device *tgt_device;
471         struct btrfs_device *src_device;
472         struct btrfs_root *root = fs_info->tree_root;
473         u8 uuid_tmp[BTRFS_UUID_SIZE];
474         struct btrfs_trans_handle *trans;
475         int ret = 0;
476
477         /* don't allow cancel or unmount to disturb the finishing procedure */
478         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
479
480         btrfs_dev_replace_lock(dev_replace);
481         /* was the operation canceled, or is it finished? */
482         if (dev_replace->replace_state !=
483             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
484                 btrfs_dev_replace_unlock(dev_replace);
485                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
486                 return 0;
487         }
488
489         tgt_device = dev_replace->tgtdev;
490         src_device = dev_replace->srcdev;
491         btrfs_dev_replace_unlock(dev_replace);
492
493         /*
494          * flush all outstanding I/O and inode extent mappings before the
495          * copy operation is declared as being finished
496          */
497         ret = btrfs_start_delalloc_roots(root->fs_info, 0, -1);
498         if (ret) {
499                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
500                 return ret;
501         }
502         btrfs_wait_ordered_roots(root->fs_info, -1);
503
504         trans = btrfs_start_transaction(root, 0);
505         if (IS_ERR(trans)) {
506                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
507                 return PTR_ERR(trans);
508         }
509         ret = btrfs_commit_transaction(trans, root);
510         WARN_ON(ret);
511
512         mutex_lock(&uuid_mutex);
513         /* keep away write_all_supers() during the finishing procedure */
514         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
515         mutex_lock(&root->fs_info->chunk_mutex);
516         btrfs_dev_replace_lock(dev_replace);
517         dev_replace->replace_state =
518                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
519                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
520         dev_replace->tgtdev = NULL;
521         dev_replace->srcdev = NULL;
522         dev_replace->time_stopped = get_seconds();
523         dev_replace->item_needs_writeback = 1;
524
525         /* replace old device with new one in mapping tree */
526         if (!scrub_ret) {
527                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
528                                                                 src_device,
529                                                                 tgt_device);
530         } else {
531                 printk_in_rcu(KERN_ERR
532                               "BTRFS: btrfs_scrub_dev(%s, %llu, %s) failed %d\n",
533                               src_device->missing ? "<missing disk>" :
534                                 rcu_str_deref(src_device->name),
535                               src_device->devid,
536                               rcu_str_deref(tgt_device->name), scrub_ret);
537                 btrfs_dev_replace_unlock(dev_replace);
538                 mutex_unlock(&root->fs_info->chunk_mutex);
539                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
540                 mutex_unlock(&uuid_mutex);
541                 if (tgt_device)
542                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
543                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
544
545                 return 0;
546         }
547
548         printk_in_rcu(KERN_INFO
549                       "BTRFS: dev_replace from %s (devid %llu) to %s finished\n",
550                       src_device->missing ? "<missing disk>" :
551                         rcu_str_deref(src_device->name),
552                       src_device->devid,
553                       rcu_str_deref(tgt_device->name));
554         tgt_device->is_tgtdev_for_dev_replace = 0;
555         tgt_device->devid = src_device->devid;
556         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
557         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
558         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
559         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
560         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
561         btrfs_device_set_disk_total_bytes(tgt_device,
562                                           src_device->disk_total_bytes);
563         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
564         ASSERT(list_empty(&src_device->resized_list));
565         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
566         tgt_device->commit_bytes_used = src_device->bytes_used;
567         if (fs_info->sb->s_bdev == src_device->bdev)
568                 fs_info->sb->s_bdev = tgt_device->bdev;
569         if (fs_info->fs_devices->latest_bdev == src_device->bdev)
570                 fs_info->fs_devices->latest_bdev = tgt_device->bdev;
571         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
572         fs_info->fs_devices->rw_devices++;
573
574         /* replace the sysfs entry */
575         btrfs_kobj_rm_device(fs_info, src_device);
576         btrfs_kobj_add_device(fs_info, tgt_device);
577
578         btrfs_dev_replace_unlock(dev_replace);
579
580         btrfs_rm_dev_replace_blocked(fs_info);
581
582         btrfs_rm_dev_replace_srcdev(fs_info, src_device);
583
584         btrfs_rm_dev_replace_unblocked(fs_info);
585
586         /*
587          * this is again a consistent state where no dev_replace procedure
588          * is running, the target device is part of the filesystem, the
589          * source device is not part of the filesystem anymore and its 1st
590          * superblock is scratched out so that it is no longer marked to
591          * belong to this filesystem.
592          */
593         mutex_unlock(&root->fs_info->chunk_mutex);
594         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
595         mutex_unlock(&uuid_mutex);
596
597         /* write back the superblocks */
598         trans = btrfs_start_transaction(root, 0);
599         if (!IS_ERR(trans))
600                 btrfs_commit_transaction(trans, root);
601
602         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
603
604         return 0;
605 }
606
607 static void btrfs_dev_replace_update_device_in_mapping_tree(
608                                                 struct btrfs_fs_info *fs_info,
609                                                 struct btrfs_device *srcdev,
610                                                 struct btrfs_device *tgtdev)
611 {
612         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
613         struct extent_map *em;
614         struct map_lookup *map;
615         u64 start = 0;
616         int i;
617
618         write_lock(&em_tree->lock);
619         do {
620                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
621                 if (!em)
622                         break;
623                 map = (struct map_lookup *)em->bdev;
624                 for (i = 0; i < map->num_stripes; i++)
625                         if (srcdev == map->stripes[i].dev)
626                                 map->stripes[i].dev = tgtdev;
627                 start = em->start + em->len;
628                 free_extent_map(em);
629         } while (start);
630         write_unlock(&em_tree->lock);
631 }
632
633 static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
634                                          char *srcdev_name,
635                                          struct btrfs_device **device)
636 {
637         int ret;
638
639         if (srcdevid) {
640                 ret = 0;
641                 *device = btrfs_find_device(root->fs_info, srcdevid, NULL,
642                                             NULL);
643                 if (!*device)
644                         ret = -ENOENT;
645         } else {
646                 ret = btrfs_find_device_missing_or_by_path(root, srcdev_name,
647                                                            device);
648         }
649         return ret;
650 }
651
652 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
653                               struct btrfs_ioctl_dev_replace_args *args)
654 {
655         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
656         struct btrfs_device *srcdev;
657
658         btrfs_dev_replace_lock(dev_replace);
659         /* even if !dev_replace_is_valid, the values are good enough for
660          * the replace_status ioctl */
661         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
662         args->status.replace_state = dev_replace->replace_state;
663         args->status.time_started = dev_replace->time_started;
664         args->status.time_stopped = dev_replace->time_stopped;
665         args->status.num_write_errors =
666                 atomic64_read(&dev_replace->num_write_errors);
667         args->status.num_uncorrectable_read_errors =
668                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
669         switch (dev_replace->replace_state) {
670         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
671         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
672                 args->status.progress_1000 = 0;
673                 break;
674         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
675                 args->status.progress_1000 = 1000;
676                 break;
677         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
678         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
679                 srcdev = dev_replace->srcdev;
680                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
681                         div64_u64(btrfs_device_get_total_bytes(srcdev), 1000));
682                 break;
683         }
684         btrfs_dev_replace_unlock(dev_replace);
685 }
686
687 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
688                              struct btrfs_ioctl_dev_replace_args *args)
689 {
690         args->result = __btrfs_dev_replace_cancel(fs_info);
691         return 0;
692 }
693
694 static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
695 {
696         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
697         struct btrfs_device *tgt_device = NULL;
698         struct btrfs_trans_handle *trans;
699         struct btrfs_root *root = fs_info->tree_root;
700         u64 result;
701         int ret;
702
703         if (fs_info->sb->s_flags & MS_RDONLY)
704                 return -EROFS;
705
706         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
707         btrfs_dev_replace_lock(dev_replace);
708         switch (dev_replace->replace_state) {
709         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
710         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
711         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
712                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
713                 btrfs_dev_replace_unlock(dev_replace);
714                 goto leave;
715         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
716         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
717                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
718                 tgt_device = dev_replace->tgtdev;
719                 dev_replace->tgtdev = NULL;
720                 dev_replace->srcdev = NULL;
721                 break;
722         }
723         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
724         dev_replace->time_stopped = get_seconds();
725         dev_replace->item_needs_writeback = 1;
726         btrfs_dev_replace_unlock(dev_replace);
727         btrfs_scrub_cancel(fs_info);
728
729         trans = btrfs_start_transaction(root, 0);
730         if (IS_ERR(trans)) {
731                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
732                 return PTR_ERR(trans);
733         }
734         ret = btrfs_commit_transaction(trans, root);
735         WARN_ON(ret);
736         if (tgt_device)
737                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
738
739 leave:
740         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
741         return result;
742 }
743
744 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
745 {
746         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
747
748         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
749         btrfs_dev_replace_lock(dev_replace);
750         switch (dev_replace->replace_state) {
751         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
752         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
753         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
754         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
755                 break;
756         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
757                 dev_replace->replace_state =
758                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
759                 dev_replace->time_stopped = get_seconds();
760                 dev_replace->item_needs_writeback = 1;
761                 btrfs_info(fs_info, "suspending dev_replace for unmount");
762                 break;
763         }
764
765         btrfs_dev_replace_unlock(dev_replace);
766         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
767 }
768
769 /* resume dev_replace procedure that was interrupted by unmount */
770 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
771 {
772         struct task_struct *task;
773         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
774
775         btrfs_dev_replace_lock(dev_replace);
776         switch (dev_replace->replace_state) {
777         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
778         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
779         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
780                 btrfs_dev_replace_unlock(dev_replace);
781                 return 0;
782         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
783                 break;
784         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
785                 dev_replace->replace_state =
786                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
787                 break;
788         }
789         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
790                 btrfs_info(fs_info, "cannot continue dev_replace, tgtdev is missing");
791                 btrfs_info(fs_info,
792                         "you may cancel the operation after 'mount -o degraded'");
793                 btrfs_dev_replace_unlock(dev_replace);
794                 return 0;
795         }
796         btrfs_dev_replace_unlock(dev_replace);
797
798         WARN_ON(atomic_xchg(
799                 &fs_info->mutually_exclusive_operation_running, 1));
800         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
801         return PTR_ERR_OR_ZERO(task);
802 }
803
804 static int btrfs_dev_replace_kthread(void *data)
805 {
806         struct btrfs_fs_info *fs_info = data;
807         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
808         struct btrfs_ioctl_dev_replace_args *status_args;
809         u64 progress;
810
811         status_args = kzalloc(sizeof(*status_args), GFP_NOFS);
812         if (status_args) {
813                 btrfs_dev_replace_status(fs_info, status_args);
814                 progress = status_args->status.progress_1000;
815                 kfree(status_args);
816                 do_div(progress, 10);
817                 printk_in_rcu(KERN_INFO
818                         "BTRFS: continuing dev_replace from %s (devid %llu) to %s @%u%%\n",
819                         dev_replace->srcdev->missing ? "<missing disk>" :
820                         rcu_str_deref(dev_replace->srcdev->name),
821                         dev_replace->srcdev->devid,
822                         dev_replace->tgtdev ?
823                         rcu_str_deref(dev_replace->tgtdev->name) :
824                         "<missing target disk>",
825                         (unsigned int)progress);
826         }
827         btrfs_dev_replace_continue_on_mount(fs_info);
828         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
829
830         return 0;
831 }
832
833 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
834 {
835         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
836         int ret;
837
838         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
839                               dev_replace->committed_cursor_left,
840                               btrfs_device_get_total_bytes(dev_replace->srcdev),
841                               &dev_replace->scrub_progress, 0, 1);
842         ret = btrfs_dev_replace_finishing(fs_info, ret);
843         WARN_ON(ret);
844         return 0;
845 }
846
847 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
848 {
849         if (!dev_replace->is_valid)
850                 return 0;
851
852         switch (dev_replace->replace_state) {
853         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
854         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
855         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
856                 return 0;
857         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
858         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
859                 /*
860                  * return true even if tgtdev is missing (this is
861                  * something that can happen if the dev_replace
862                  * procedure is suspended by an umount and then
863                  * the tgtdev is missing (or "btrfs dev scan") was
864                  * not called and the the filesystem is remounted
865                  * in degraded state. This does not stop the
866                  * dev_replace procedure. It needs to be canceled
867                  * manually if the cancelation is wanted.
868                  */
869                 break;
870         }
871         return 1;
872 }
873
874 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
875 {
876         /* the beginning is just an optimization for the typical case */
877         if (atomic_read(&dev_replace->nesting_level) == 0) {
878 acquire_lock:
879                 /* this is not a nested case where the same thread
880                  * is trying to acqurire the same lock twice */
881                 mutex_lock(&dev_replace->lock);
882                 mutex_lock(&dev_replace->lock_management_lock);
883                 dev_replace->lock_owner = current->pid;
884                 atomic_inc(&dev_replace->nesting_level);
885                 mutex_unlock(&dev_replace->lock_management_lock);
886                 return;
887         }
888
889         mutex_lock(&dev_replace->lock_management_lock);
890         if (atomic_read(&dev_replace->nesting_level) > 0 &&
891             dev_replace->lock_owner == current->pid) {
892                 WARN_ON(!mutex_is_locked(&dev_replace->lock));
893                 atomic_inc(&dev_replace->nesting_level);
894                 mutex_unlock(&dev_replace->lock_management_lock);
895                 return;
896         }
897
898         mutex_unlock(&dev_replace->lock_management_lock);
899         goto acquire_lock;
900 }
901
902 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
903 {
904         WARN_ON(!mutex_is_locked(&dev_replace->lock));
905         mutex_lock(&dev_replace->lock_management_lock);
906         WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
907         WARN_ON(dev_replace->lock_owner != current->pid);
908         atomic_dec(&dev_replace->nesting_level);
909         if (atomic_read(&dev_replace->nesting_level) == 0) {
910                 dev_replace->lock_owner = 0;
911                 mutex_unlock(&dev_replace->lock_management_lock);
912                 mutex_unlock(&dev_replace->lock);
913         } else {
914                 mutex_unlock(&dev_replace->lock_management_lock);
915         }
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_dec(struct btrfs_fs_info *fs_info)
924 {
925         percpu_counter_dec(&fs_info->bio_counter);
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         DEFINE_WAIT(wait);
934 again:
935         percpu_counter_inc(&fs_info->bio_counter);
936         if (test_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state)) {
937                 btrfs_bio_counter_dec(fs_info);
938                 wait_event(fs_info->replace_wait,
939                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
940                                      &fs_info->fs_state));
941                 goto again;
942         }
943
944 }