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TOMOYO Linux Cross Reference
Linux/fs/btrfs/dev-replace.c

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  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         ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
411                                             src_device, &tgt_device);
412         if (ret)
413                 return ret;
414 
415         /*
416          * Here we commit the transaction to make sure commit_total_bytes
417          * of all the devices are updated.
418          */
419         trans = btrfs_attach_transaction(root);
420         if (!IS_ERR(trans)) {
421                 ret = btrfs_commit_transaction(trans);
422                 if (ret)
423                         return ret;
424         } else if (PTR_ERR(trans) != -ENOENT) {
425                 return PTR_ERR(trans);
426         }
427 
428         need_unlock = true;
429         btrfs_dev_replace_write_lock(dev_replace);
430         switch (dev_replace->replace_state) {
431         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
432         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
433         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
434                 break;
435         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
436         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
437                 ASSERT(0);
438                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
439                 goto leave;
440         }
441 
442         dev_replace->cont_reading_from_srcdev_mode = read_src;
443         WARN_ON(!src_device);
444         dev_replace->srcdev = src_device;
445         dev_replace->tgtdev = tgt_device;
446 
447         btrfs_info_in_rcu(fs_info,
448                       "dev_replace from %s (devid %llu) to %s started",
449                       btrfs_dev_name(src_device),
450                       src_device->devid,
451                       rcu_str_deref(tgt_device->name));
452 
453         /*
454          * from now on, the writes to the srcdev are all duplicated to
455          * go to the tgtdev as well (refer to btrfs_map_block()).
456          */
457         dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
458         dev_replace->time_started = ktime_get_real_seconds();
459         dev_replace->cursor_left = 0;
460         dev_replace->committed_cursor_left = 0;
461         dev_replace->cursor_left_last_write_of_item = 0;
462         dev_replace->cursor_right = 0;
463         dev_replace->is_valid = 1;
464         dev_replace->item_needs_writeback = 1;
465         atomic64_set(&dev_replace->num_write_errors, 0);
466         atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
467         btrfs_dev_replace_write_unlock(dev_replace);
468         need_unlock = false;
469 
470         ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
471         if (ret)
472                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
473 
474         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
475 
476         /* force writing the updated state information to disk */
477         trans = btrfs_start_transaction(root, 0);
478         if (IS_ERR(trans)) {
479                 ret = PTR_ERR(trans);
480                 need_unlock = true;
481                 btrfs_dev_replace_write_lock(dev_replace);
482                 dev_replace->replace_state =
483                         BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
484                 dev_replace->srcdev = NULL;
485                 dev_replace->tgtdev = NULL;
486                 goto leave;
487         }
488 
489         ret = btrfs_commit_transaction(trans);
490         WARN_ON(ret);
491 
492         /* the disk copy procedure reuses the scrub code */
493         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
494                               btrfs_device_get_total_bytes(src_device),
495                               &dev_replace->scrub_progress, 0, 1);
496 
497         ret = btrfs_dev_replace_finishing(fs_info, ret);
498         if (ret == -EINPROGRESS) {
499                 ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
500         } else {
501                 WARN_ON(ret);
502         }
503 
504         return ret;
505 
506 leave:
507         if (need_unlock)
508                 btrfs_dev_replace_write_unlock(dev_replace);
509         btrfs_destroy_dev_replace_tgtdev(tgt_device);
510         return ret;
511 }
512 
513 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
514                             struct btrfs_ioctl_dev_replace_args *args)
515 {
516         int ret;
517 
518         switch (args->start.cont_reading_from_srcdev_mode) {
519         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
520         case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
521                 break;
522         default:
523                 return -EINVAL;
524         }
525 
526         if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
527             args->start.tgtdev_name[0] == '\0')
528                 return -EINVAL;
529 
530         ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
531                                         args->start.srcdevid,
532                                         args->start.srcdev_name,
533                                         args->start.cont_reading_from_srcdev_mode);
534         args->result = ret;
535         /* don't warn if EINPROGRESS, someone else might be running scrub */
536         if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS)
537                 ret = 0;
538 
539         return ret;
540 }
541 
542 /*
543  * blocked until all in-flight bios operations are finished.
544  */
545 static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
546 {
547         set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
548         wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
549                    &fs_info->dev_replace.bio_counter));
550 }
551 
552 /*
553  * we have removed target device, it is safe to allow new bios request.
554  */
555 static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
556 {
557         clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
558         wake_up(&fs_info->dev_replace.replace_wait);
559 }
560 
561 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
562                                        int scrub_ret)
563 {
564         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
565         struct btrfs_device *tgt_device;
566         struct btrfs_device *src_device;
567         struct btrfs_root *root = fs_info->tree_root;
568         u8 uuid_tmp[BTRFS_UUID_SIZE];
569         struct btrfs_trans_handle *trans;
570         int ret = 0;
571 
572         /* don't allow cancel or unmount to disturb the finishing procedure */
573         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
574 
575         btrfs_dev_replace_read_lock(dev_replace);
576         /* was the operation canceled, or is it finished? */
577         if (dev_replace->replace_state !=
578             BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
579                 btrfs_dev_replace_read_unlock(dev_replace);
580                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
581                 return 0;
582         }
583 
584         tgt_device = dev_replace->tgtdev;
585         src_device = dev_replace->srcdev;
586         btrfs_dev_replace_read_unlock(dev_replace);
587 
588         /*
589          * flush all outstanding I/O and inode extent mappings before the
590          * copy operation is declared as being finished
591          */
592         ret = btrfs_start_delalloc_roots(fs_info, -1);
593         if (ret) {
594                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
595                 return ret;
596         }
597         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
598 
599         trans = btrfs_start_transaction(root, 0);
600         if (IS_ERR(trans)) {
601                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
602                 return PTR_ERR(trans);
603         }
604         ret = btrfs_commit_transaction(trans);
605         WARN_ON(ret);
606 
607         /* keep away write_all_supers() during the finishing procedure */
608         mutex_lock(&fs_info->fs_devices->device_list_mutex);
609         mutex_lock(&fs_info->chunk_mutex);
610         btrfs_dev_replace_write_lock(dev_replace);
611         dev_replace->replace_state =
612                 scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
613                           : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
614         dev_replace->tgtdev = NULL;
615         dev_replace->srcdev = NULL;
616         dev_replace->time_stopped = ktime_get_real_seconds();
617         dev_replace->item_needs_writeback = 1;
618 
619         /* replace old device with new one in mapping tree */
620         if (!scrub_ret) {
621                 btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
622                                                                 src_device,
623                                                                 tgt_device);
624         } else {
625                 btrfs_err_in_rcu(fs_info,
626                                  "btrfs_scrub_dev(%s, %llu, %s) failed %d",
627                                  btrfs_dev_name(src_device),
628                                  src_device->devid,
629                                  rcu_str_deref(tgt_device->name), scrub_ret);
630                 btrfs_dev_replace_write_unlock(dev_replace);
631                 mutex_unlock(&fs_info->chunk_mutex);
632                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
633                 btrfs_rm_dev_replace_blocked(fs_info);
634                 if (tgt_device)
635                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
636                 btrfs_rm_dev_replace_unblocked(fs_info);
637                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
638 
639                 return scrub_ret;
640         }
641 
642         btrfs_info_in_rcu(fs_info,
643                           "dev_replace from %s (devid %llu) to %s finished",
644                           btrfs_dev_name(src_device),
645                           src_device->devid,
646                           rcu_str_deref(tgt_device->name));
647         clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
648         tgt_device->devid = src_device->devid;
649         src_device->devid = BTRFS_DEV_REPLACE_DEVID;
650         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
651         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
652         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
653         btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
654         btrfs_device_set_disk_total_bytes(tgt_device,
655                                           src_device->disk_total_bytes);
656         btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
657         ASSERT(list_empty(&src_device->resized_list));
658         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
659         tgt_device->commit_bytes_used = src_device->bytes_used;
660 
661         btrfs_assign_next_active_device(src_device, tgt_device);
662 
663         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
664         fs_info->fs_devices->rw_devices++;
665 
666         btrfs_dev_replace_write_unlock(dev_replace);
667 
668         btrfs_rm_dev_replace_blocked(fs_info);
669 
670         btrfs_rm_dev_replace_remove_srcdev(src_device);
671 
672         btrfs_rm_dev_replace_unblocked(fs_info);
673 
674         /*
675          * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
676          * update on-disk dev stats value during commit transaction
677          */
678         atomic_inc(&tgt_device->dev_stats_ccnt);
679 
680         /*
681          * this is again a consistent state where no dev_replace procedure
682          * is running, the target device is part of the filesystem, the
683          * source device is not part of the filesystem anymore and its 1st
684          * superblock is scratched out so that it is no longer marked to
685          * belong to this filesystem.
686          */
687         mutex_unlock(&fs_info->chunk_mutex);
688         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
689 
690         /* replace the sysfs entry */
691         btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device);
692         btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
693 
694         /* write back the superblocks */
695         trans = btrfs_start_transaction(root, 0);
696         if (!IS_ERR(trans))
697                 btrfs_commit_transaction(trans);
698 
699         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
700 
701         return 0;
702 }
703 
704 static void btrfs_dev_replace_update_device_in_mapping_tree(
705                                                 struct btrfs_fs_info *fs_info,
706                                                 struct btrfs_device *srcdev,
707                                                 struct btrfs_device *tgtdev)
708 {
709         struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
710         struct extent_map *em;
711         struct map_lookup *map;
712         u64 start = 0;
713         int i;
714 
715         write_lock(&em_tree->lock);
716         do {
717                 em = lookup_extent_mapping(em_tree, start, (u64)-1);
718                 if (!em)
719                         break;
720                 map = em->map_lookup;
721                 for (i = 0; i < map->num_stripes; i++)
722                         if (srcdev == map->stripes[i].dev)
723                                 map->stripes[i].dev = tgtdev;
724                 start = em->start + em->len;
725                 free_extent_map(em);
726         } while (start);
727         write_unlock(&em_tree->lock);
728 }
729 
730 /*
731  * Read progress of device replace status according to the state and last
732  * stored position. The value format is the same as for
733  * btrfs_dev_replace::progress_1000
734  */
735 static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
736 {
737         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
738         u64 ret = 0;
739 
740         switch (dev_replace->replace_state) {
741         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
742         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
743                 ret = 0;
744                 break;
745         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
746                 ret = 1000;
747                 break;
748         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
749         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
750                 ret = div64_u64(dev_replace->cursor_left,
751                                 div_u64(btrfs_device_get_total_bytes(
752                                                 dev_replace->srcdev), 1000));
753                 break;
754         }
755 
756         return ret;
757 }
758 
759 void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
760                               struct btrfs_ioctl_dev_replace_args *args)
761 {
762         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
763 
764         btrfs_dev_replace_read_lock(dev_replace);
765         /* even if !dev_replace_is_valid, the values are good enough for
766          * the replace_status ioctl */
767         args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
768         args->status.replace_state = dev_replace->replace_state;
769         args->status.time_started = dev_replace->time_started;
770         args->status.time_stopped = dev_replace->time_stopped;
771         args->status.num_write_errors =
772                 atomic64_read(&dev_replace->num_write_errors);
773         args->status.num_uncorrectable_read_errors =
774                 atomic64_read(&dev_replace->num_uncorrectable_read_errors);
775         args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
776         btrfs_dev_replace_read_unlock(dev_replace);
777 }
778 
779 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
780 {
781         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
782         struct btrfs_device *tgt_device = NULL;
783         struct btrfs_device *src_device = NULL;
784         struct btrfs_trans_handle *trans;
785         struct btrfs_root *root = fs_info->tree_root;
786         int result;
787         int ret;
788 
789         if (sb_rdonly(fs_info->sb))
790                 return -EROFS;
791 
792         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
793         btrfs_dev_replace_write_lock(dev_replace);
794         switch (dev_replace->replace_state) {
795         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
796         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
797         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
798                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
799                 btrfs_dev_replace_write_unlock(dev_replace);
800                 break;
801         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
802                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
803                 tgt_device = dev_replace->tgtdev;
804                 src_device = dev_replace->srcdev;
805                 btrfs_dev_replace_write_unlock(dev_replace);
806                 btrfs_scrub_cancel(fs_info);
807                 /* btrfs_dev_replace_finishing() will handle the cleanup part */
808                 btrfs_info_in_rcu(fs_info,
809                         "dev_replace from %s (devid %llu) to %s canceled",
810                         btrfs_dev_name(src_device), src_device->devid,
811                         btrfs_dev_name(tgt_device));
812                 break;
813         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
814                 /*
815                  * Scrub doing the replace isn't running so we need to do the
816                  * cleanup step of btrfs_dev_replace_finishing() here
817                  */
818                 result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
819                 tgt_device = dev_replace->tgtdev;
820                 src_device = dev_replace->srcdev;
821                 dev_replace->tgtdev = NULL;
822                 dev_replace->srcdev = NULL;
823                 dev_replace->replace_state =
824                                 BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
825                 dev_replace->time_stopped = ktime_get_real_seconds();
826                 dev_replace->item_needs_writeback = 1;
827 
828                 btrfs_dev_replace_write_unlock(dev_replace);
829 
830                 btrfs_scrub_cancel(fs_info);
831 
832                 trans = btrfs_start_transaction(root, 0);
833                 if (IS_ERR(trans)) {
834                         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
835                         return PTR_ERR(trans);
836                 }
837                 ret = btrfs_commit_transaction(trans);
838                 WARN_ON(ret);
839 
840                 btrfs_info_in_rcu(fs_info,
841                 "suspended dev_replace from %s (devid %llu) to %s canceled",
842                         btrfs_dev_name(src_device), src_device->devid,
843                         btrfs_dev_name(tgt_device));
844 
845                 if (tgt_device)
846                         btrfs_destroy_dev_replace_tgtdev(tgt_device);
847                 break;
848         default:
849                 result = -EINVAL;
850         }
851 
852         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
853         return result;
854 }
855 
856 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
857 {
858         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
859 
860         mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
861         btrfs_dev_replace_write_lock(dev_replace);
862         switch (dev_replace->replace_state) {
863         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
864         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
865         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
866         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
867                 break;
868         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
869                 dev_replace->replace_state =
870                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
871                 dev_replace->time_stopped = ktime_get_real_seconds();
872                 dev_replace->item_needs_writeback = 1;
873                 btrfs_info(fs_info, "suspending dev_replace for unmount");
874                 break;
875         }
876 
877         btrfs_dev_replace_write_unlock(dev_replace);
878         mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
879 }
880 
881 /* resume dev_replace procedure that was interrupted by unmount */
882 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
883 {
884         struct task_struct *task;
885         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
886 
887         btrfs_dev_replace_write_lock(dev_replace);
888         switch (dev_replace->replace_state) {
889         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
890         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
891         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
892                 btrfs_dev_replace_write_unlock(dev_replace);
893                 return 0;
894         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
895                 break;
896         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
897                 dev_replace->replace_state =
898                         BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
899                 break;
900         }
901         if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
902                 btrfs_info(fs_info,
903                            "cannot continue dev_replace, tgtdev is missing");
904                 btrfs_info(fs_info,
905                            "you may cancel the operation after 'mount -o degraded'");
906                 dev_replace->replace_state =
907                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
908                 btrfs_dev_replace_write_unlock(dev_replace);
909                 return 0;
910         }
911         btrfs_dev_replace_write_unlock(dev_replace);
912 
913         /*
914          * This could collide with a paused balance, but the exclusive op logic
915          * should never allow both to start and pause. We don't want to allow
916          * dev-replace to start anyway.
917          */
918         if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
919                 btrfs_dev_replace_write_lock(dev_replace);
920                 dev_replace->replace_state =
921                                         BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
922                 btrfs_dev_replace_write_unlock(dev_replace);
923                 btrfs_info(fs_info,
924                 "cannot resume dev-replace, other exclusive operation running");
925                 return 0;
926         }
927 
928         task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
929         return PTR_ERR_OR_ZERO(task);
930 }
931 
932 static int btrfs_dev_replace_kthread(void *data)
933 {
934         struct btrfs_fs_info *fs_info = data;
935         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
936         u64 progress;
937         int ret;
938 
939         progress = btrfs_dev_replace_progress(fs_info);
940         progress = div_u64(progress, 10);
941         btrfs_info_in_rcu(fs_info,
942                 "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
943                 btrfs_dev_name(dev_replace->srcdev),
944                 dev_replace->srcdev->devid,
945                 btrfs_dev_name(dev_replace->tgtdev),
946                 (unsigned int)progress);
947 
948         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
949                               dev_replace->committed_cursor_left,
950                               btrfs_device_get_total_bytes(dev_replace->srcdev),
951                               &dev_replace->scrub_progress, 0, 1);
952         ret = btrfs_dev_replace_finishing(fs_info, ret);
953         WARN_ON(ret);
954 
955         clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
956         return 0;
957 }
958 
959 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
960 {
961         if (!dev_replace->is_valid)
962                 return 0;
963 
964         switch (dev_replace->replace_state) {
965         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
966         case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
967         case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
968                 return 0;
969         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
970         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
971                 /*
972                  * return true even if tgtdev is missing (this is
973                  * something that can happen if the dev_replace
974                  * procedure is suspended by an umount and then
975                  * the tgtdev is missing (or "btrfs dev scan") was
976                  * not called and the the filesystem is remounted
977                  * in degraded state. This does not stop the
978                  * dev_replace procedure. It needs to be canceled
979                  * manually if the cancellation is wanted.
980                  */
981                 break;
982         }
983         return 1;
984 }
985 
986 void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace)
987 {
988         read_lock(&dev_replace->lock);
989 }
990 
991 void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace)
992 {
993         read_unlock(&dev_replace->lock);
994 }
995 
996 void btrfs_dev_replace_write_lock(struct btrfs_dev_replace *dev_replace)
997 {
998 again:
999         wait_event(dev_replace->read_lock_wq,
1000                    atomic_read(&dev_replace->blocking_readers) == 0);
1001         write_lock(&dev_replace->lock);
1002         if (atomic_read(&dev_replace->blocking_readers)) {
1003                 write_unlock(&dev_replace->lock);
1004                 goto again;
1005         }
1006 }
1007 
1008 void btrfs_dev_replace_write_unlock(struct btrfs_dev_replace *dev_replace)
1009 {
1010         write_unlock(&dev_replace->lock);
1011 }
1012 
1013 /* inc blocking cnt and release read lock */
1014 void btrfs_dev_replace_set_lock_blocking(
1015                                         struct btrfs_dev_replace *dev_replace)
1016 {
1017         /* only set blocking for read lock */
1018         atomic_inc(&dev_replace->blocking_readers);
1019         read_unlock(&dev_replace->lock);
1020 }
1021 
1022 void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
1023 {
1024         percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1025 }
1026 
1027 void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
1028 {
1029         percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
1030         cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
1031 }
1032 
1033 void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
1034 {
1035         while (1) {
1036                 percpu_counter_inc(&fs_info->dev_replace.bio_counter);
1037                 if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1038                                      &fs_info->fs_state)))
1039                         break;
1040 
1041                 btrfs_bio_counter_dec(fs_info);
1042                 wait_event(fs_info->dev_replace.replace_wait,
1043                            !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
1044                                      &fs_info->fs_state));
1045         }
1046 }
1047 

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