46092e67f61a48a6d2b4340915a2d64aad3fd44f
[sfrench/cifs-2.6.git] / fs / btrfs / dev-replace.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) STRATO AG 2012.  All rights reserved.
4  */
5
6 #include <linux/sched.h>
7 #include <linux/bio.h>
8 #include <linux/slab.h>
9 #include <linux/blkdev.h>
10 #include <linux/kthread.h>
11 #include <linux/math64.h>
12 #include "ctree.h"
13 #include "extent_map.h"
14 #include "disk-io.h"
15 #include "transaction.h"
16 #include "print-tree.h"
17 #include "volumes.h"
18 #include "async-thread.h"
19 #include "check-integrity.h"
20 #include "rcu-string.h"
21 #include "dev-replace.h"
22 #include "sysfs.h"
23
24 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
25                                        int scrub_ret);
26 static void btrfs_dev_replace_update_device_in_mapping_tree(
27                                                 struct btrfs_fs_info *fs_info,
28                                                 struct btrfs_device *srcdev,
29                                                 struct btrfs_device *tgtdev);
30 static int btrfs_dev_replace_kthread(void *data);
31
32 int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
33 {
34         struct btrfs_key key;
35         struct btrfs_root *dev_root = fs_info->dev_root;
36         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
37         struct extent_buffer *eb;
38         int slot;
39         int ret = 0;
40         struct btrfs_path *path = NULL;
41         int item_size;
42         struct btrfs_dev_replace_item *ptr;
43         u64 src_devid;
44
45         path = btrfs_alloc_path();
46         if (!path) {
47                 ret = -ENOMEM;
48                 goto out;
49         }
50
51         key.objectid = 0;
52         key.type = BTRFS_DEV_REPLACE_KEY;
53         key.offset = 0;
54         ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
55         if (ret) {
56 no_valid_dev_replace_entry_found:
57                 ret = 0;
58                 dev_replace->replace_state =
59                         BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED;
60                 dev_replace->cont_reading_from_srcdev_mode =
61                     BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
62                 dev_replace->replace_state = 0;
63                 dev_replace->time_started = 0;
64                 dev_replace->time_stopped = 0;
65                 atomic64_set(&dev_replace->num_write_errors, 0);
66                 atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
67                 dev_replace->cursor_left = 0;
68                 dev_replace->committed_cursor_left = 0;
69                 dev_replace->cursor_left_last_write_of_item = 0;
70                 dev_replace->cursor_right = 0;
71                 dev_replace->srcdev = NULL;
72                 dev_replace->tgtdev = NULL;
73                 dev_replace->is_valid = 0;
74                 dev_replace->item_needs_writeback = 0;
75                 goto out;
76         }
77         slot = path->slots[0];
78         eb = path->nodes[0];
79         item_size = btrfs_item_size_nr(eb, slot);
80         ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
81
82         if (item_size != sizeof(struct btrfs_dev_replace_item)) {
83                 btrfs_warn(fs_info,
84                         "dev_replace entry found has unexpected size, ignore entry");
85                 goto no_valid_dev_replace_entry_found;
86         }
87
88         src_devid = btrfs_dev_replace_src_devid(eb, ptr);
89         dev_replace->cont_reading_from_srcdev_mode =
90                 btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
91         dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
92         dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
93         dev_replace->time_stopped =
94                 btrfs_dev_replace_time_stopped(eb, ptr);
95         atomic64_set(&dev_replace->num_write_errors,
96                      btrfs_dev_replace_num_write_errors(eb, ptr));
97         atomic64_set(&dev_replace->num_uncorrectable_read_errors,
98                      btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
99         dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
100         dev_replace->committed_cursor_left = dev_replace->cursor_left;
101         dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
102         dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
103         dev_replace->is_valid = 1;
104
105         dev_replace->item_needs_writeback = 0;
106         switch (dev_replace->replace_state) {
107         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
108         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
109         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
110                 dev_replace->srcdev = NULL;
111                 dev_replace->tgtdev = NULL;
112                 break;
113         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
114         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
115                 dev_replace->srcdev = btrfs_find_device(fs_info, src_devid,
116                                                         NULL, NULL);
117                 dev_replace->tgtdev = btrfs_find_device(fs_info,
118                                                         BTRFS_DEV_REPLACE_DEVID,
119                                                         NULL, NULL);
120                 /*
121                  * allow 'btrfs dev replace_cancel' if src/tgt device is
122                  * missing
123                  */
124                 if (!dev_replace->srcdev &&
125                     !btrfs_test_opt(fs_info, DEGRADED)) {
126                         ret = -EIO;
127                         btrfs_warn(fs_info,
128                            "cannot mount because device replace operation is ongoing and");
129                         btrfs_warn(fs_info,
130                            "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
131                            src_devid);
132                 }
133                 if (!dev_replace->tgtdev &&
134                     !btrfs_test_opt(fs_info, DEGRADED)) {
135                         ret = -EIO;
136                         btrfs_warn(fs_info,
137                            "cannot mount because device replace operation is ongoing and");
138                         btrfs_warn(fs_info,
139                            "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
140                                 BTRFS_DEV_REPLACE_DEVID);
141                 }
142                 if (dev_replace->tgtdev) {
143                         if (dev_replace->srcdev) {
144                                 dev_replace->tgtdev->total_bytes =
145                                         dev_replace->srcdev->total_bytes;
146                                 dev_replace->tgtdev->disk_total_bytes =
147                                         dev_replace->srcdev->disk_total_bytes;
148                                 dev_replace->tgtdev->commit_total_bytes =
149                                         dev_replace->srcdev->commit_total_bytes;
150                                 dev_replace->tgtdev->bytes_used =
151                                         dev_replace->srcdev->bytes_used;
152                                 dev_replace->tgtdev->commit_bytes_used =
153                                         dev_replace->srcdev->commit_bytes_used;
154                         }
155                         set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
156                                 &dev_replace->tgtdev->dev_state);
157
158                         WARN_ON(fs_info->fs_devices->rw_devices == 0);
159                         dev_replace->tgtdev->io_width = fs_info->sectorsize;
160                         dev_replace->tgtdev->io_align = fs_info->sectorsize;
161                         dev_replace->tgtdev->sector_size = fs_info->sectorsize;
162                         dev_replace->tgtdev->fs_info = fs_info;
163                         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
164                                 &dev_replace->tgtdev->dev_state);
165                 }
166                 break;
167         }
168
169 out:
170         btrfs_free_path(path);
171         return ret;
172 }
173
174 /*
175  * Initialize a new device for device replace target from a given source dev
176  * and path.
177  *
178  * Return 0 and new device in @device_out, otherwise return < 0
179  */
180 static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
181                                   const char *device_path,
182                                   struct btrfs_device *srcdev,
183                                   struct btrfs_device **device_out)
184 {
185         struct btrfs_device *device;
186         struct block_device *bdev;
187         struct list_head *devices;
188         struct rcu_string *name;
189         u64 devid = BTRFS_DEV_REPLACE_DEVID;
190         int ret = 0;
191
192         *device_out = NULL;
193         if (fs_info->fs_devices->seeding) {
194                 btrfs_err(fs_info, "the filesystem is a seed filesystem!");
195                 return -EINVAL;
196         }
197
198         bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
199                                   fs_info->bdev_holder);
200         if (IS_ERR(bdev)) {
201                 btrfs_err(fs_info, "target device %s is invalid!", device_path);
202                 return PTR_ERR(bdev);
203         }
204
205         filemap_write_and_wait(bdev->bd_inode->i_mapping);
206
207         devices = &fs_info->fs_devices->devices;
208         list_for_each_entry(device, devices, dev_list) {
209                 if (device->bdev == bdev) {
210                         btrfs_err(fs_info,
211                                   "target device is in the filesystem!");
212                         ret = -EEXIST;
213                         goto error;
214                 }
215         }
216
217
218         if (i_size_read(bdev->bd_inode) <
219             btrfs_device_get_total_bytes(srcdev)) {
220                 btrfs_err(fs_info,
221                           "target device is smaller than source device!");
222                 ret = -EINVAL;
223                 goto error;
224         }
225
226
227         device = btrfs_alloc_device(NULL, &devid, NULL);
228         if (IS_ERR(device)) {
229                 ret = PTR_ERR(device);
230                 goto error;
231         }
232
233         name = rcu_string_strdup(device_path, GFP_KERNEL);
234         if (!name) {
235                 btrfs_free_device(device);
236                 ret = -ENOMEM;
237                 goto error;
238         }
239         rcu_assign_pointer(device->name, name);
240
241         mutex_lock(&fs_info->fs_devices->device_list_mutex);
242         set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
243         device->generation = 0;
244         device->io_width = fs_info->sectorsize;
245         device->io_align = fs_info->sectorsize;
246         device->sector_size = fs_info->sectorsize;
247         device->total_bytes = btrfs_device_get_total_bytes(srcdev);
248         device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
249         device->bytes_used = btrfs_device_get_bytes_used(srcdev);
250         device->commit_total_bytes = srcdev->commit_total_bytes;
251         device->commit_bytes_used = device->bytes_used;
252         device->fs_info = fs_info;
253         device->bdev = bdev;
254         set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
255         set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
256         device->mode = FMODE_EXCL;
257         device->dev_stats_valid = 1;
258         set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
259         device->fs_devices = fs_info->fs_devices;
260         list_add(&device->dev_list, &fs_info->fs_devices->devices);
261         fs_info->fs_devices->num_devices++;
262         fs_info->fs_devices->open_devices++;
263         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
264
265         *device_out = device;
266         return 0;
267
268 error:
269         blkdev_put(bdev, FMODE_EXCL);
270         return ret;
271 }
272
273 /*
274  * called from commit_transaction. Writes changed device replace state to
275  * disk.
276  */
277 int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
278                           struct btrfs_fs_info *fs_info)
279 {
280         int ret;
281         struct btrfs_root *dev_root = fs_info->dev_root;
282         struct btrfs_path *path;
283         struct btrfs_key key;
284         struct extent_buffer *eb;
285         struct btrfs_dev_replace_item *ptr;
286         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
287
288         btrfs_dev_replace_read_lock(dev_replace);
289         if (!dev_replace->is_valid ||
290             !dev_replace->item_needs_writeback) {
291                 btrfs_dev_replace_read_unlock(dev_replace);
292                 return 0;
293         }
294         btrfs_dev_replace_read_unlock(dev_replace);
295
296         key.objectid = 0;
297         key.type = BTRFS_DEV_REPLACE_KEY;
298         key.offset = 0;
299
300         path = btrfs_alloc_path();
301         if (!path) {
302                 ret = -ENOMEM;
303                 goto out;
304         }
305         ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
306         if (ret < 0) {
307                 btrfs_warn(fs_info,
308                            "error %d while searching for dev_replace item!",
309                            ret);
310                 goto out;
311         }
312
313         if (ret == 0 &&
314             btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
315                 /*
316                  * need to delete old one and insert a new one.
317                  * Since no attempt is made to recover any old state, if the
318                  * dev_replace state is 'running', the data on the target
319                  * drive is lost.
320                  * It would be possible to recover the state: just make sure
321                  * that the beginning of the item is never changed and always
322                  * contains all the essential information. Then read this
323                  * minimal set of information and use it as a base for the
324                  * new state.
325                  */
326                 ret = btrfs_del_item(trans, dev_root, path);
327                 if (ret != 0) {
328                         btrfs_warn(fs_info,
329                                    "delete too small dev_replace item failed %d!",
330                                    ret);
331                         goto out;
332                 }
333                 ret = 1;
334         }
335
336         if (ret == 1) {
337                 /* need to insert a new item */
338                 btrfs_release_path(path);
339                 ret = btrfs_insert_empty_item(trans, dev_root, path,
340                                               &key, sizeof(*ptr));
341                 if (ret < 0) {
342                         btrfs_warn(fs_info,
343                                    "insert dev_replace item failed %d!", ret);
344                         goto out;
345                 }
346         }
347
348         eb = path->nodes[0];
349         ptr = btrfs_item_ptr(eb, path->slots[0],
350                              struct btrfs_dev_replace_item);
351
352         btrfs_dev_replace_write_lock(dev_replace);
353         if (dev_replace->srcdev)
354                 btrfs_set_dev_replace_src_devid(eb, ptr,
355                         dev_replace->srcdev->devid);
356         else
357                 btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
358         btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
359                 dev_replace->cont_reading_from_srcdev_mode);
360         btrfs_set_dev_replace_replace_state(eb, ptr,
361                 dev_replace->replace_state);
362         btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
363         btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
364         btrfs_set_dev_replace_num_write_errors(eb, ptr,
365                 atomic64_read(&dev_replace->num_write_errors));
366         btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
367                 atomic64_read(&dev_replace->num_uncorrectable_read_errors));
368         dev_replace->cursor_left_last_write_of_item =
369                 dev_replace->cursor_left;
370         btrfs_set_dev_replace_cursor_left(eb, ptr,
371                 dev_replace->cursor_left_last_write_of_item);
372         btrfs_set_dev_replace_cursor_right(eb, ptr,
373                 dev_replace->cursor_right);
374         dev_replace->item_needs_writeback = 0;
375         btrfs_dev_replace_write_unlock(dev_replace);
376
377         btrfs_mark_buffer_dirty(eb);
378
379 out:
380         btrfs_free_path(path);
381
382         return ret;
383 }
384
385 static char* btrfs_dev_name(struct btrfs_device *device)
386 {
387         if (!device || test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
388                 return "<missing disk>";
389         else
390                 return rcu_str_deref(device->name);
391 }
392
393 int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
394                 const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
395                 int read_src)
396 {
397         struct btrfs_root *root = fs_info->dev_root;
398         struct btrfs_trans_handle *trans;
399         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
400         int ret;
401         struct btrfs_device *tgt_device = NULL;
402         struct btrfs_device *src_device = NULL;
403         bool need_unlock;
404
405         src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,
406                                                   srcdev_name);
407         if (IS_ERR(src_device))
408                 return PTR_ERR(src_device);
409
410         if (btrfs_pinned_by_swapfile(fs_info, src_device)) {
411                 btrfs_warn_in_rcu(fs_info,
412           "cannot replace device %s (devid %llu) due to active swapfile",
413                         btrfs_dev_name(src_device), src_device->devid);
414                 return -ETXTBSY;
415         }
416
417         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
418                                             src_device, &tgt_device);
419         if (ret)
420                 return ret;
421
422         /*
423          * Here we commit the transaction to make sure commit_total_bytes
424          * of all the devices are updated.
425          */
426         trans = btrfs_attach_transaction(root);
427         if (!IS_ERR(trans)) {
428                 ret = btrfs_commit_transaction(trans);
429                 if (ret)
430                         return ret;
431         } else if (PTR_ERR(trans) != -ENOENT) {
432                 return PTR_ERR(trans);
433         }
434
435         need_unlock = true;
436         btrfs_dev_replace_write_lock(dev_replace);
437         switch (dev_replace->replace_state) {
438         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
439         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
440         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
441                 break;
442         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
443         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
444                 ASSERT(0);
445                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
446                 goto leave;
447         }
448
449         dev_replace->cont_reading_from_srcdev_mode = read_src;
450         WARN_ON(!src_device);
451         dev_replace->srcdev = src_device;
452         dev_replace->tgtdev = tgt_device;
453
454         btrfs_info_in_rcu(fs_info,
455                       "dev_replace from %s (devid %llu) to %s started",
456                       btrfs_dev_name(src_device),
457                       src_device->devid,
458                       rcu_str_deref(tgt_device->name));
459
460         /*
461          * from now on, the writes to the srcdev are all duplicated to
462          * go to the tgtdev as well (refer to btrfs_map_block()).
463          */
464         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
465         dev_replace->time_started = ktime_get_real_seconds();
466         dev_replace->cursor_left = 0;
467         dev_replace->committed_cursor_left = 0;
468         dev_replace->cursor_left_last_write_of_item = 0;
469         dev_replace->cursor_right = 0;
470         dev_replace->is_valid = 1;
471         dev_replace->item_needs_writeback = 1;
472         atomic64_set(&dev_replace->num_write_errors, 0);
473         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
474         btrfs_dev_replace_write_unlock(dev_replace);
475         need_unlock = false;
476
477         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
478         if (ret)
479                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
480
481         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
482
483         /* force writing the updated state information to disk */
484         trans = btrfs_start_transaction(root, 0);
485         if (IS_ERR(trans)) {
486                 ret = PTR_ERR(trans);
487                 need_unlock = true;
488                 btrfs_dev_replace_write_lock(dev_replace);
489                 dev_replace->replace_state =
490                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
491                 dev_replace->srcdev = NULL;
492                 dev_replace->tgtdev = NULL;
493                 goto leave;
494         }
495
496         ret = btrfs_commit_transaction(trans);
497         WARN_ON(ret);
498
499         /* the disk copy procedure reuses the scrub code */
500         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
501                               btrfs_device_get_total_bytes(src_device),
502                               &dev_replace->scrub_progress, 0, 1);
503
504         ret = btrfs_dev_replace_finishing(fs_info, ret);
505         if (ret == -EINPROGRESS) {
506                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
507         } else {
508                 WARN_ON(ret);
509         }
510
511         return ret;
512
513 leave:
514         if (need_unlock)
515                 btrfs_dev_replace_write_unlock(dev_replace);
516         btrfs_destroy_dev_replace_tgtdev(tgt_device);
517         return ret;
518 }
519
520 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
521                             struct btrfs_ioctl_dev_replace_args *args)
522 {
523         int ret;
524
525         switch (args->start.cont_reading_from_srcdev_mode) {
526         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
527         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
528                 break;
529         default:
530                 return -EINVAL;
531         }
532
533         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
534             args->start.tgtdev_name[0] == '\0')
535                 return -EINVAL;
536
537         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
538                                         args->start.srcdevid,
539                                         args->start.srcdev_name,
540                                         args->start.cont_reading_from_srcdev_mode);
541         args->result = ret;
542         /* don't warn if EINPROGRESS, someone else might be running scrub */
543         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
544                 ret = 0;
545
546         return ret;
547 }
548
549 /*
550  * blocked until all in-flight bios operations are finished.
551  */
552 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
553 {
554         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
555         wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
556                    &fs_info->dev_replace.bio_counter));
557 }
558
559 /*
560  * we have removed target device, it is safe to allow new bios request.
561  */
562 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
563 {
564         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
565         wake_up(&fs_info->dev_replace.replace_wait);
566 }
567
568 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
569                                        int scrub_ret)
570 {
571         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
572         struct btrfs_device *tgt_device;
573         struct btrfs_device *src_device;
574         struct btrfs_root *root = fs_info->tree_root;
575         u8 uuid_tmp[BTRFS_UUID_SIZE];
576         struct btrfs_trans_handle *trans;
577         int ret = 0;
578
579         /* don't allow cancel or unmount to disturb the finishing procedure */
580         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
581
582         btrfs_dev_replace_read_lock(dev_replace);
583         /* was the operation canceled, or is it finished? */
584         if (dev_replace->replace_state !=
585             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
586                 btrfs_dev_replace_read_unlock(dev_replace);
587                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
588                 return 0;
589         }
590
591         tgt_device = dev_replace->tgtdev;
592         src_device = dev_replace->srcdev;
593         btrfs_dev_replace_read_unlock(dev_replace);
594
595         /*
596          * flush all outstanding I/O and inode extent mappings before the
597          * copy operation is declared as being finished
598          */
599         ret = btrfs_start_delalloc_roots(fs_info, -1);
600         if (ret) {
601                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
602                 return ret;
603         }
604         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
605
606         trans = btrfs_start_transaction(root, 0);
607         if (IS_ERR(trans)) {
608                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
609                 return PTR_ERR(trans);
610         }
611         ret = btrfs_commit_transaction(trans);
612         WARN_ON(ret);
613
614         /* keep away write_all_supers() during the finishing procedure */
615         mutex_lock(&fs_info->fs_devices->device_list_mutex);
616         mutex_lock(&fs_info->chunk_mutex);
617         btrfs_dev_replace_write_lock(dev_replace);
618         dev_replace->replace_state =
619                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
620                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
621         dev_replace->tgtdev = NULL;
622         dev_replace->srcdev = NULL;
623         dev_replace->time_stopped = ktime_get_real_seconds();
624         dev_replace->item_needs_writeback = 1;
625
626         /* replace old device with new one in mapping tree */
627         if (!scrub_ret) {
628                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
629                                                                 src_device,
630                                                                 tgt_device);
631         } else {
632                 btrfs_err_in_rcu(fs_info,
633                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
634                                  btrfs_dev_name(src_device),
635                                  src_device->devid,
636                                  rcu_str_deref(tgt_device->name), scrub_ret);
637                 btrfs_dev_replace_write_unlock(dev_replace);
638                 mutex_unlock(&fs_info->chunk_mutex);
639                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
640                 btrfs_rm_dev_replace_blocked(fs_info);
641                 if (tgt_device)
642                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
643                 btrfs_rm_dev_replace_unblocked(fs_info);
644                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
645
646                 return scrub_ret;
647         }
648
649         btrfs_info_in_rcu(fs_info,
650                           "dev_replace from %s (devid %llu) to %s finished",
651                           btrfs_dev_name(src_device),
652                           src_device->devid,
653                           rcu_str_deref(tgt_device->name));
654         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
655         tgt_device->devid = src_device->devid;
656         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
657         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
658         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
659         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
660         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
661         btrfs_device_set_disk_total_bytes(tgt_device,
662                                           src_device->disk_total_bytes);
663         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
664         ASSERT(list_empty(&src_device->resized_list));
665         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
666         tgt_device->commit_bytes_used = src_device->bytes_used;
667
668         btrfs_assign_next_active_device(src_device, tgt_device);
669
670         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
671         fs_info->fs_devices->rw_devices++;
672
673         btrfs_dev_replace_write_unlock(dev_replace);
674
675         btrfs_rm_dev_replace_blocked(fs_info);
676
677         btrfs_rm_dev_replace_remove_srcdev(src_device);
678
679         btrfs_rm_dev_replace_unblocked(fs_info);
680
681         /*
682          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
683          * update on-disk dev stats value during commit transaction
684          */
685         atomic_inc(&tgt_device->dev_stats_ccnt);
686
687         /*
688          * this is again a consistent state where no dev_replace procedure
689          * is running, the target device is part of the filesystem, the
690          * source device is not part of the filesystem anymore and its 1st
691          * superblock is scratched out so that it is no longer marked to
692          * belong to this filesystem.
693          */
694         mutex_unlock(&fs_info->chunk_mutex);
695         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
696
697         /* replace the sysfs entry */
698         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
699         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
700
701         /* write back the superblocks */
702         trans = btrfs_start_transaction(root, 0);
703         if (!IS_ERR(trans))
704                 btrfs_commit_transaction(trans);
705
706         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
707
708         return 0;
709 }
710
711 static void btrfs_dev_replace_update_device_in_mapping_tree(
712                                                 struct btrfs_fs_info *fs_info,
713                                                 struct btrfs_device *srcdev,
714                                                 struct btrfs_device *tgtdev)
715 {
716         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
717         struct extent_map *em;
718         struct map_lookup *map;
719         u64 start = 0;
720         int i;
721
722         write_lock(&em_tree->lock);
723         do {
724                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
725                 if (!em)
726                         break;
727                 map = em->map_lookup;
728                 for (i = 0; i < map->num_stripes; i++)
729                         if (srcdev == map->stripes[i].dev)
730                                 map->stripes[i].dev = tgtdev;
731                 start = em->start + em->len;
732                 free_extent_map(em);
733         } while (start);
734         write_unlock(&em_tree->lock);
735 }
736
737 /*
738  * Read progress of device replace status according to the state and last
739  * stored position. The value format is the same as for
740  * btrfs_dev_replace::progress_1000
741  */
742 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
743 {
744         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
745         u64 ret = 0;
746
747         switch (dev_replace->replace_state) {
748         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
749         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
750                 ret = 0;
751                 break;
752         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
753                 ret = 1000;
754                 break;
755         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
756         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
757                 ret = div64_u64(dev_replace->cursor_left,
758                                 div_u64(btrfs_device_get_total_bytes(
759                                                 dev_replace->srcdev), 1000));
760                 break;
761         }
762
763         return ret;
764 }
765
766 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
767                               struct btrfs_ioctl_dev_replace_args *args)
768 {
769         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
770
771         btrfs_dev_replace_read_lock(dev_replace);
772         /* even if !dev_replace_is_valid, the values are good enough for
773          * the replace_status ioctl */
774         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
775         args->status.replace_state = dev_replace->replace_state;
776         args->status.time_started = dev_replace->time_started;
777         args->status.time_stopped = dev_replace->time_stopped;
778         args->status.num_write_errors =
779                 atomic64_read(&dev_replace->num_write_errors);
780         args->status.num_uncorrectable_read_errors =
781                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
782         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
783         btrfs_dev_replace_read_unlock(dev_replace);
784 }
785
786 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
787 {
788         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
789         struct btrfs_device *tgt_device = NULL;
790         struct btrfs_device *src_device = NULL;
791         struct btrfs_trans_handle *trans;
792         struct btrfs_root *root = fs_info->tree_root;
793         int result;
794         int ret;
795
796         if (sb_rdonly(fs_info->sb))
797                 return -EROFS;
798
799         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
800         btrfs_dev_replace_write_lock(dev_replace);
801         switch (dev_replace->replace_state) {
802         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
803         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
804         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
805                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
806                 btrfs_dev_replace_write_unlock(dev_replace);
807                 goto leave;
808         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
809         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
810                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
811                 tgt_device = dev_replace->tgtdev;
812                 src_device = dev_replace->srcdev;
813                 dev_replace->tgtdev = NULL;
814                 dev_replace->srcdev = NULL;
815                 break;
816         }
817         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
818         dev_replace->time_stopped = ktime_get_real_seconds();
819         dev_replace->item_needs_writeback = 1;
820         btrfs_dev_replace_write_unlock(dev_replace);
821         btrfs_scrub_cancel(fs_info);
822
823         trans = btrfs_start_transaction(root, 0);
824         if (IS_ERR(trans)) {
825                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
826                 return PTR_ERR(trans);
827         }
828         ret = btrfs_commit_transaction(trans);
829         WARN_ON(ret);
830
831         btrfs_info_in_rcu(fs_info,
832                 "dev_replace from %s (devid %llu) to %s canceled",
833                 btrfs_dev_name(src_device), src_device->devid,
834                 btrfs_dev_name(tgt_device));
835
836         if (tgt_device)
837                 btrfs_destroy_dev_replace_tgtdev(tgt_device);
838
839 leave:
840         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
841         return result;
842 }
843
844 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
845 {
846         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
847
848         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
849         btrfs_dev_replace_write_lock(dev_replace);
850         switch (dev_replace->replace_state) {
851         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
852         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
853         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
854         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
855                 break;
856         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
857                 dev_replace->replace_state =
858                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
859                 dev_replace->time_stopped = ktime_get_real_seconds();
860                 dev_replace->item_needs_writeback = 1;
861                 btrfs_info(fs_info, "suspending dev_replace for unmount");
862                 break;
863         }
864
865         btrfs_dev_replace_write_unlock(dev_replace);
866         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
867 }
868
869 /* resume dev_replace procedure that was interrupted by unmount */
870 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
871 {
872         struct task_struct *task;
873         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
874
875         btrfs_dev_replace_write_lock(dev_replace);
876         switch (dev_replace->replace_state) {
877         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
878         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
879         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
880                 btrfs_dev_replace_write_unlock(dev_replace);
881                 return 0;
882         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
883                 break;
884         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
885                 dev_replace->replace_state =
886                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
887                 break;
888         }
889         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
890                 btrfs_info(fs_info,
891                            "cannot continue dev_replace, tgtdev is missing");
892                 btrfs_info(fs_info,
893                            "you may cancel the operation after 'mount -o degraded'");
894                 btrfs_dev_replace_write_unlock(dev_replace);
895                 return 0;
896         }
897         btrfs_dev_replace_write_unlock(dev_replace);
898
899         /*
900          * This could collide with a paused balance, but the exclusive op logic
901          * should never allow both to start and pause. We don't want to allow
902          * dev-replace to start anyway.
903          */
904         if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
905                 btrfs_info(fs_info,
906                 "cannot resume dev-replace, other exclusive operation running");
907                 return 0;
908         }
909
910         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
911         return PTR_ERR_OR_ZERO(task);
912 }
913
914 static int btrfs_dev_replace_kthread(void *data)
915 {
916         struct btrfs_fs_info *fs_info = data;
917         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
918         u64 progress;
919         int ret;
920
921         progress = btrfs_dev_replace_progress(fs_info);
922         progress = div_u64(progress, 10);
923         btrfs_info_in_rcu(fs_info,
924                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
925                 btrfs_dev_name(dev_replace->srcdev),
926                 dev_replace->srcdev->devid,
927                 btrfs_dev_name(dev_replace->tgtdev),
928                 (unsigned int)progress);
929
930         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
931                               dev_replace->committed_cursor_left,
932                               btrfs_device_get_total_bytes(dev_replace->srcdev),
933                               &dev_replace->scrub_progress, 0, 1);
934         ret = btrfs_dev_replace_finishing(fs_info, ret);
935         WARN_ON(ret);
936
937         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
938         return 0;
939 }
940
941 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
942 {
943         if (!dev_replace->is_valid)
944                 return 0;
945
946         switch (dev_replace->replace_state) {
947         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
948         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
949         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
950                 return 0;
951         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
952         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
953                 /*
954                  * return true even if tgtdev is missing (this is
955                  * something that can happen if the dev_replace
956                  * procedure is suspended by an umount and then
957                  * the tgtdev is missing (or "btrfs dev scan") was
958                  * not called and the the filesystem is remounted
959                  * in degraded state. This does not stop the
960                  * dev_replace procedure. It needs to be canceled
961                  * manually if the cancellation is wanted.
962                  */
963                 break;
964         }
965         return 1;
966 }
967
968 void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace)
969 {
970         read_lock(&dev_replace->lock);
971 }
972
973 void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace)
974 {
975         read_unlock(&dev_replace->lock);
976 }
977
978 void btrfs_dev_replace_write_lock(struct btrfs_dev_replace *dev_replace)
979 {
980 again:
981         wait_event(dev_replace->read_lock_wq,
982                    atomic_read(&dev_replace->blocking_readers) == 0);
983         write_lock(&dev_replace->lock);
984         if (atomic_read(&dev_replace->blocking_readers)) {
985                 write_unlock(&dev_replace->lock);
986                 goto again;
987         }
988 }
989
990 void btrfs_dev_replace_write_unlock(struct btrfs_dev_replace *dev_replace)
991 {
992         write_unlock(&dev_replace->lock);
993 }
994
995 /* inc blocking cnt and release read lock */
996 void btrfs_dev_replace_set_lock_blocking(
997                                         struct btrfs_dev_replace *dev_replace)
998 {
999         /* only set blocking for read lock */
1000         atomic_inc(&dev_replace->blocking_readers);
1001         read_unlock(&dev_replace->lock);
1002 }
1003
1004 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
1005 {
1006         percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1007 }
1008
1009 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1010 {
1011         percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1012         cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1013 }
1014
1015 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1016 {
1017         while (1) {
1018                 percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1019                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1020                                      &fs_info->fs_state)))
1021                         break;
1022
1023                 btrfs_bio_counter_dec(fs_info);
1024                 wait_event(fs_info->dev_replace.replace_wait,
1025                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1026                                      &fs_info->fs_state));
1027         }
1028 }