a428d528220f4cc1e112fa1c72372c392fc23fa3
[sfrench/cifs-2.6.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_kthread(void *data);
48 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info);
49
50
51 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
52 {
53         struct btrfs_key key;
54         struct btrfs_root *dev_root = fs_info->dev_root;
55         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
56         struct extent_buffer *eb;
57         int slot;
58         int ret = 0;
59         struct btrfs_path *path = NULL;
60         int item_size;
61         struct btrfs_dev_replace_item *ptr;
62         u64 src_devid;
63
64         path = btrfs_alloc_path();
65         if (!path) {
66                 ret = -ENOMEM;
67                 goto out;
68         }
69
70         key.objectid = 0;
71         key.type = BTRFS_DEV_REPLACE_KEY;
72         key.offset = 0;
73         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
74         if (ret) {
75 no_valid_dev_replace_entry_found:
76                 ret = 0;
77                 dev_replace->replace_state =
78                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
79                 dev_replace->cont_reading_from_srcdev_mode =
80                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
81                 dev_replace->replace_state = 0;
82                 dev_replace->time_started = 0;
83                 dev_replace->time_stopped = 0;
84                 atomic64_set(&dev_replace->num_write_errors, 0);
85                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
86                 dev_replace->cursor_left = 0;
87                 dev_replace->committed_cursor_left = 0;
88                 dev_replace->cursor_left_last_write_of_item = 0;
89                 dev_replace->cursor_right = 0;
90                 dev_replace->srcdev = NULL;
91                 dev_replace->tgtdev = NULL;
92                 dev_replace->is_valid = 0;
93                 dev_replace->item_needs_writeback = 0;
94                 goto out;
95         }
96         slot = path->slots[0];
97         eb = path->nodes[0];
98         item_size = btrfs_item_size_nr(eb, slot);
99         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
100
101         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
102                 btrfs_warn(fs_info,
103                         "dev_replace entry found has unexpected size, ignore entry");
104                 goto no_valid_dev_replace_entry_found;
105         }
106
107         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
108         dev_replace->cont_reading_from_srcdev_mode =
109                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
110         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
111         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
112         dev_replace->time_stopped =
113                 btrfs_dev_replace_time_stopped(eb, ptr);
114         atomic64_set(&dev_replace->num_write_errors,
115                      btrfs_dev_replace_num_write_errors(eb, ptr));
116         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
117                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
118         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
119         dev_replace->committed_cursor_left = dev_replace->cursor_left;
120         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
121         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
122         dev_replace->is_valid = 1;
123
124         dev_replace->item_needs_writeback = 0;
125         switch (dev_replace->replace_state) {
126         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
127         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
128         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
129                 dev_replace->srcdev = NULL;
130                 dev_replace->tgtdev = NULL;
131                 break;
132         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
133         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
134                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
135                                                         NULL, NULL);
136                 dev_replace->tgtdev = btrfs_find_device(fs_info,
137                                                         BTRFS_DEV_REPLACE_DEVID,
138                                                         NULL, NULL);
139                 /*
140                  * allow 'btrfs dev replace_cancel' if src/tgt device is
141                  * missing
142                  */
143                 if (!dev_replace->srcdev &&
144                     !btrfs_test_opt(fs_info, DEGRADED)) {
145                         ret = -EIO;
146                         btrfs_warn(fs_info,
147                            "cannot mount because device replace operation is ongoing and");
148                         btrfs_warn(fs_info,
149                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
150                            src_devid);
151                 }
152                 if (!dev_replace->tgtdev &&
153                     !btrfs_test_opt(fs_info, DEGRADED)) {
154                         ret = -EIO;
155                         btrfs_warn(fs_info,
156                            "cannot mount because device replace operation is ongoing and");
157                         btrfs_warn(fs_info,
158                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
159                                 BTRFS_DEV_REPLACE_DEVID);
160                 }
161                 if (dev_replace->tgtdev) {
162                         if (dev_replace->srcdev) {
163                                 dev_replace->tgtdev->total_bytes =
164                                         dev_replace->srcdev->total_bytes;
165                                 dev_replace->tgtdev->disk_total_bytes =
166                                         dev_replace->srcdev->disk_total_bytes;
167                                 dev_replace->tgtdev->commit_total_bytes =
168                                         dev_replace->srcdev->commit_total_bytes;
169                                 dev_replace->tgtdev->bytes_used =
170                                         dev_replace->srcdev->bytes_used;
171                                 dev_replace->tgtdev->commit_bytes_used =
172                                         dev_replace->srcdev->commit_bytes_used;
173                         }
174                         set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
175                                 &dev_replace->tgtdev->dev_state);
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 static char* btrfs_dev_name(struct btrfs_device *device)
308 {
309         if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
310                 return "<missing disk>";
311         else
312                 return rcu_str_deref(device->name);
313 }
314
315 int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
316                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
317                 int read_src)
318 {
319         struct btrfs_root *root = fs_info->dev_root;
320         struct btrfs_trans_handle *trans;
321         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
322         int ret;
323         struct btrfs_device *tgt_device = NULL;
324         struct btrfs_device *src_device = NULL;
325
326         /* the disk copy procedure reuses the scrub code */
327         mutex_lock(&fs_info->volume_mutex);
328         ret = btrfs_find_device_by_devspec(fs_info, srcdevid,
329                                             srcdev_name, &src_device);
330         if (ret) {
331                 mutex_unlock(&fs_info->volume_mutex);
332                 return ret;
333         }
334
335         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
336                                             src_device, &tgt_device);
337         mutex_unlock(&fs_info->volume_mutex);
338         if (ret)
339                 return ret;
340
341         /*
342          * Here we commit the transaction to make sure commit_total_bytes
343          * of all the devices are updated.
344          */
345         trans = btrfs_attach_transaction(root);
346         if (!IS_ERR(trans)) {
347                 ret = btrfs_commit_transaction(trans);
348                 if (ret)
349                         return ret;
350         } else if (PTR_ERR(trans) != -ENOENT) {
351                 return PTR_ERR(trans);
352         }
353
354         btrfs_dev_replace_lock(dev_replace, 1);
355         switch (dev_replace->replace_state) {
356         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
357         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
358         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
359                 break;
360         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
361         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
362                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
363                 goto leave;
364         }
365
366         dev_replace->cont_reading_from_srcdev_mode = read_src;
367         WARN_ON(!src_device);
368         dev_replace->srcdev = src_device;
369         WARN_ON(!tgt_device);
370         dev_replace->tgtdev = tgt_device;
371
372         btrfs_info_in_rcu(fs_info,
373                       "dev_replace from %s (devid %llu) to %s started",
374                       btrfs_dev_name(src_device),
375                       src_device->devid,
376                       rcu_str_deref(tgt_device->name));
377
378         /*
379          * from now on, the writes to the srcdev are all duplicated to
380          * go to the tgtdev as well (refer to btrfs_map_block()).
381          */
382         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
383         dev_replace->time_started = get_seconds();
384         dev_replace->cursor_left = 0;
385         dev_replace->committed_cursor_left = 0;
386         dev_replace->cursor_left_last_write_of_item = 0;
387         dev_replace->cursor_right = 0;
388         dev_replace->is_valid = 1;
389         dev_replace->item_needs_writeback = 1;
390         atomic64_set(&dev_replace->num_write_errors, 0);
391         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
392         btrfs_dev_replace_unlock(dev_replace, 1);
393
394         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
395         if (ret)
396                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
397
398         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
399
400         /* force writing the updated state information to disk */
401         trans = btrfs_start_transaction(root, 0);
402         if (IS_ERR(trans)) {
403                 ret = PTR_ERR(trans);
404                 btrfs_dev_replace_lock(dev_replace, 1);
405                 goto leave;
406         }
407
408         ret = btrfs_commit_transaction(trans);
409         WARN_ON(ret);
410
411         /* the disk copy procedure reuses the scrub code */
412         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
413                               btrfs_device_get_total_bytes(src_device),
414                               &dev_replace->scrub_progress, 0, 1);
415
416         ret = btrfs_dev_replace_finishing(fs_info, ret);
417         if (ret == -EINPROGRESS) {
418                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
419         } else {
420                 WARN_ON(ret);
421         }
422
423         return ret;
424
425 leave:
426         dev_replace->srcdev = NULL;
427         dev_replace->tgtdev = NULL;
428         btrfs_dev_replace_unlock(dev_replace, 1);
429         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
430         return ret;
431 }
432
433 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
434                             struct btrfs_ioctl_dev_replace_args *args)
435 {
436         int ret;
437
438         switch (args->start.cont_reading_from_srcdev_mode) {
439         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
440         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
441                 break;
442         default:
443                 return -EINVAL;
444         }
445
446         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
447             args->start.tgtdev_name[0] == '\0')
448                 return -EINVAL;
449
450         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
451                                         args->start.srcdevid,
452                                         args->start.srcdev_name,
453                                         args->start.cont_reading_from_srcdev_mode);
454         args->result = ret;
455         /* don't warn if EINPROGRESS, someone else might be running scrub */
456         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
457                 ret = 0;
458
459         return ret;
460 }
461
462 /*
463  * blocked until all in-flight bios operations are finished.
464  */
465 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
466 {
467         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
468         wait_event(fs_info->replace_wait, !percpu_counter_sum(
469                    &fs_info->bio_counter));
470 }
471
472 /*
473  * we have removed target device, it is safe to allow new bios request.
474  */
475 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
476 {
477         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
478         wake_up(&fs_info->replace_wait);
479 }
480
481 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
482                                        int scrub_ret)
483 {
484         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
485         struct btrfs_device *tgt_device;
486         struct btrfs_device *src_device;
487         struct btrfs_root *root = fs_info->tree_root;
488         u8 uuid_tmp[BTRFS_UUID_SIZE];
489         struct btrfs_trans_handle *trans;
490         int ret = 0;
491
492         /* don't allow cancel or unmount to disturb the finishing procedure */
493         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
494
495         btrfs_dev_replace_lock(dev_replace, 0);
496         /* was the operation canceled, or is it finished? */
497         if (dev_replace->replace_state !=
498             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
499                 btrfs_dev_replace_unlock(dev_replace, 0);
500                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
501                 return 0;
502         }
503
504         tgt_device = dev_replace->tgtdev;
505         src_device = dev_replace->srcdev;
506         btrfs_dev_replace_unlock(dev_replace, 0);
507
508         /*
509          * flush all outstanding I/O and inode extent mappings before the
510          * copy operation is declared as being finished
511          */
512         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
513         if (ret) {
514                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
515                 return ret;
516         }
517         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
518
519         trans = btrfs_start_transaction(root, 0);
520         if (IS_ERR(trans)) {
521                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
522                 return PTR_ERR(trans);
523         }
524         ret = btrfs_commit_transaction(trans);
525         WARN_ON(ret);
526
527         mutex_lock(&uuid_mutex);
528         /* keep away write_all_supers() during the finishing procedure */
529         mutex_lock(&fs_info->fs_devices->device_list_mutex);
530         mutex_lock(&fs_info->chunk_mutex);
531         btrfs_dev_replace_lock(dev_replace, 1);
532         dev_replace->replace_state =
533                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
534                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
535         dev_replace->tgtdev = NULL;
536         dev_replace->srcdev = NULL;
537         dev_replace->time_stopped = get_seconds();
538         dev_replace->item_needs_writeback = 1;
539
540         /* replace old device with new one in mapping tree */
541         if (!scrub_ret) {
542                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
543                                                                 src_device,
544                                                                 tgt_device);
545         } else {
546                 btrfs_err_in_rcu(fs_info,
547                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
548                                  btrfs_dev_name(src_device),
549                                  src_device->devid,
550                                  rcu_str_deref(tgt_device->name), scrub_ret);
551                 btrfs_dev_replace_unlock(dev_replace, 1);
552                 mutex_unlock(&fs_info->chunk_mutex);
553                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
554                 mutex_unlock(&uuid_mutex);
555                 btrfs_rm_dev_replace_blocked(fs_info);
556                 if (tgt_device)
557                         btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
558                 btrfs_rm_dev_replace_unblocked(fs_info);
559                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
560
561                 return scrub_ret;
562         }
563
564         btrfs_info_in_rcu(fs_info,
565                           "dev_replace from %s (devid %llu) to %s finished",
566                           btrfs_dev_name(src_device),
567                           src_device->devid,
568                           rcu_str_deref(tgt_device->name));
569         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
570         tgt_device->devid = src_device->devid;
571         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
572         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
573         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
574         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
575         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
576         btrfs_device_set_disk_total_bytes(tgt_device,
577                                           src_device->disk_total_bytes);
578         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
579         ASSERT(list_empty(&src_device->resized_list));
580         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
581         tgt_device->commit_bytes_used = src_device->bytes_used;
582
583         btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
584
585         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
586         fs_info->fs_devices->rw_devices++;
587
588         btrfs_dev_replace_unlock(dev_replace, 1);
589
590         btrfs_rm_dev_replace_blocked(fs_info);
591
592         btrfs_rm_dev_replace_remove_srcdev(fs_info, src_device);
593
594         btrfs_rm_dev_replace_unblocked(fs_info);
595
596         /*
597          * this is again a consistent state where no dev_replace procedure
598          * is running, the target device is part of the filesystem, the
599          * source device is not part of the filesystem anymore and its 1st
600          * superblock is scratched out so that it is no longer marked to
601          * belong to this filesystem.
602          */
603         mutex_unlock(&fs_info->chunk_mutex);
604         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
605         mutex_unlock(&uuid_mutex);
606
607         /* replace the sysfs entry */
608         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
609         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
610
611         /* write back the superblocks */
612         trans = btrfs_start_transaction(root, 0);
613         if (!IS_ERR(trans))
614                 btrfs_commit_transaction(trans);
615
616         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
617
618         return 0;
619 }
620
621 static void btrfs_dev_replace_update_device_in_mapping_tree(
622                                                 struct btrfs_fs_info *fs_info,
623                                                 struct btrfs_device *srcdev,
624                                                 struct btrfs_device *tgtdev)
625 {
626         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
627         struct extent_map *em;
628         struct map_lookup *map;
629         u64 start = 0;
630         int i;
631
632         write_lock(&em_tree->lock);
633         do {
634                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
635                 if (!em)
636                         break;
637                 map = em->map_lookup;
638                 for (i = 0; i < map->num_stripes; i++)
639                         if (srcdev == map->stripes[i].dev)
640                                 map->stripes[i].dev = tgtdev;
641                 start = em->start + em->len;
642                 free_extent_map(em);
643         } while (start);
644         write_unlock(&em_tree->lock);
645 }
646
647 /*
648  * Read progress of device replace status according to the state and last
649  * stored position. The value format is the same as for
650  * btrfs_dev_replace::progress_1000
651  */
652 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
653 {
654         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
655         u64 ret = 0;
656
657         switch (dev_replace->replace_state) {
658         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
659         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
660                 ret = 0;
661                 break;
662         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
663                 ret = 1000;
664                 break;
665         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
666         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
667                 ret = div64_u64(dev_replace->cursor_left,
668                                 div_u64(btrfs_device_get_total_bytes(
669                                                 dev_replace->srcdev), 1000));
670                 break;
671         }
672
673         return ret;
674 }
675
676 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
677                               struct btrfs_ioctl_dev_replace_args *args)
678 {
679         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
680
681         btrfs_dev_replace_lock(dev_replace, 0);
682         /* even if !dev_replace_is_valid, the values are good enough for
683          * the replace_status ioctl */
684         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
685         args->status.replace_state = dev_replace->replace_state;
686         args->status.time_started = dev_replace->time_started;
687         args->status.time_stopped = dev_replace->time_stopped;
688         args->status.num_write_errors =
689                 atomic64_read(&dev_replace->num_write_errors);
690         args->status.num_uncorrectable_read_errors =
691                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
692         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
693         btrfs_dev_replace_unlock(dev_replace, 0);
694 }
695
696 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
697 {
698         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
699         struct btrfs_device *tgt_device = NULL;
700         struct btrfs_trans_handle *trans;
701         struct btrfs_root *root = fs_info->tree_root;
702         int result;
703         int ret;
704
705         if (sb_rdonly(fs_info->sb))
706                 return -EROFS;
707
708         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
709         btrfs_dev_replace_lock(dev_replace, 1);
710         switch (dev_replace->replace_state) {
711         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
712         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
713         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
714                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
715                 btrfs_dev_replace_unlock(dev_replace, 1);
716                 goto leave;
717         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
718         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
719                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
720                 tgt_device = dev_replace->tgtdev;
721                 dev_replace->tgtdev = NULL;
722                 dev_replace->srcdev = NULL;
723                 break;
724         }
725         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
726         dev_replace->time_stopped = get_seconds();
727         dev_replace->item_needs_writeback = 1;
728         btrfs_dev_replace_unlock(dev_replace, 1);
729         btrfs_scrub_cancel(fs_info);
730
731         trans = btrfs_start_transaction(root, 0);
732         if (IS_ERR(trans)) {
733                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
734                 return PTR_ERR(trans);
735         }
736         ret = btrfs_commit_transaction(trans);
737         WARN_ON(ret);
738         if (tgt_device)
739                 btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
740
741 leave:
742         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
743         return result;
744 }
745
746 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
747 {
748         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
749
750         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
751         btrfs_dev_replace_lock(dev_replace, 1);
752         switch (dev_replace->replace_state) {
753         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
754         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
755         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
756         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
757                 break;
758         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
759                 dev_replace->replace_state =
760                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
761                 dev_replace->time_stopped = get_seconds();
762                 dev_replace->item_needs_writeback = 1;
763                 btrfs_info(fs_info, "suspending dev_replace for unmount");
764                 break;
765         }
766
767         btrfs_dev_replace_unlock(dev_replace, 1);
768         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
769 }
770
771 /* resume dev_replace procedure that was interrupted by unmount */
772 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
773 {
774         struct task_struct *task;
775         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
776
777         btrfs_dev_replace_lock(dev_replace, 1);
778         switch (dev_replace->replace_state) {
779         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
780         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
781         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
782                 btrfs_dev_replace_unlock(dev_replace, 1);
783                 return 0;
784         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
785                 break;
786         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
787                 dev_replace->replace_state =
788                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
789                 break;
790         }
791         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
792                 btrfs_info(fs_info,
793                            "cannot continue dev_replace, tgtdev is missing");
794                 btrfs_info(fs_info,
795                            "you may cancel the operation after 'mount -o degraded'");
796                 btrfs_dev_replace_unlock(dev_replace, 1);
797                 return 0;
798         }
799         btrfs_dev_replace_unlock(dev_replace, 1);
800
801         WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
802         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
803         return PTR_ERR_OR_ZERO(task);
804 }
805
806 static int btrfs_dev_replace_kthread(void *data)
807 {
808         struct btrfs_fs_info *fs_info = data;
809         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
810         u64 progress;
811
812         progress = btrfs_dev_replace_progress(fs_info);
813         progress = div_u64(progress, 10);
814         btrfs_info_in_rcu(fs_info,
815                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
816                 btrfs_dev_name(dev_replace->srcdev),
817                 dev_replace->srcdev->devid,
818                 btrfs_dev_name(dev_replace->tgtdev),
819                 (unsigned int)progress);
820
821         btrfs_dev_replace_continue_on_mount(fs_info);
822         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
823
824         return 0;
825 }
826
827 static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
828 {
829         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
830         int ret;
831
832         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
833                               dev_replace->committed_cursor_left,
834                               btrfs_device_get_total_bytes(dev_replace->srcdev),
835                               &dev_replace->scrub_progress, 0, 1);
836         ret = btrfs_dev_replace_finishing(fs_info, ret);
837         WARN_ON(ret);
838         return 0;
839 }
840
841 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
842 {
843         if (!dev_replace->is_valid)
844                 return 0;
845
846         switch (dev_replace->replace_state) {
847         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
848         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
849         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
850                 return 0;
851         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
852         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
853                 /*
854                  * return true even if tgtdev is missing (this is
855                  * something that can happen if the dev_replace
856                  * procedure is suspended by an umount and then
857                  * the tgtdev is missing (or "btrfs dev scan") was
858                  * not called and the the filesystem is remounted
859                  * in degraded state. This does not stop the
860                  * dev_replace procedure. It needs to be canceled
861                  * manually if the cancellation is wanted.
862                  */
863                 break;
864         }
865         return 1;
866 }
867
868 void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
869 {
870         if (rw == 1) {
871                 /* write */
872 again:
873                 wait_event(dev_replace->read_lock_wq,
874                            atomic_read(&dev_replace->blocking_readers) == 0);
875                 write_lock(&dev_replace->lock);
876                 if (atomic_read(&dev_replace->blocking_readers)) {
877                         write_unlock(&dev_replace->lock);
878                         goto again;
879                 }
880         } else {
881                 read_lock(&dev_replace->lock);
882                 atomic_inc(&dev_replace->read_locks);
883         }
884 }
885
886 void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
887 {
888         if (rw == 1) {
889                 /* write */
890                 ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
891                 write_unlock(&dev_replace->lock);
892         } else {
893                 ASSERT(atomic_read(&dev_replace->read_locks) > 0);
894                 atomic_dec(&dev_replace->read_locks);
895                 read_unlock(&dev_replace->lock);
896         }
897 }
898
899 /* inc blocking cnt and release read lock */
900 void btrfs_dev_replace_set_lock_blocking(
901                                         struct btrfs_dev_replace *dev_replace)
902 {
903         /* only set blocking for read lock */
904         ASSERT(atomic_read(&dev_replace->read_locks) > 0);
905         atomic_inc(&dev_replace->blocking_readers);
906         read_unlock(&dev_replace->lock);
907 }
908
909 /* acquire read lock and dec blocking cnt */
910 void btrfs_dev_replace_clear_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         ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
916         read_lock(&dev_replace->lock);
917         if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
918             waitqueue_active(&dev_replace->read_lock_wq))
919                 wake_up(&dev_replace->read_lock_wq);
920 }
921
922 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
923 {
924         percpu_counter_inc(&fs_info->bio_counter);
925 }
926
927 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
928 {
929         percpu_counter_sub(&fs_info->bio_counter, amount);
930
931         if (waitqueue_active(&fs_info->replace_wait))
932                 wake_up(&fs_info->replace_wait);
933 }
934
935 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
936 {
937         while (1) {
938                 percpu_counter_inc(&fs_info->bio_counter);
939                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
940                                      &fs_info->fs_state)))
941                         break;
942
943                 btrfs_bio_counter_dec(fs_info);
944                 wait_event(fs_info->replace_wait,
945                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
946                                      &fs_info->fs_state));
947         }
948 }