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

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