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

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

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