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Btrfs: optionally avoid reads from device replace source drive
[~shefty/rdma-dev.git] / fs / btrfs / volumes.c
1 /*
2  * Copyright (C) 2007 Oracle.  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/ratelimit.h>
27 #include <linux/kthread.h>
28 #include "compat.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 "math.h"
39 #include "dev-replace.h"
40
41 static int init_first_rw_device(struct btrfs_trans_handle *trans,
42                                 struct btrfs_root *root,
43                                 struct btrfs_device *device);
44 static int btrfs_relocate_sys_chunks(struct btrfs_root *root);
45 static void __btrfs_reset_dev_stats(struct btrfs_device *dev);
46 static void btrfs_dev_stat_print_on_load(struct btrfs_device *device);
47
48 static DEFINE_MUTEX(uuid_mutex);
49 static LIST_HEAD(fs_uuids);
50
51 static void lock_chunks(struct btrfs_root *root)
52 {
53         mutex_lock(&root->fs_info->chunk_mutex);
54 }
55
56 static void unlock_chunks(struct btrfs_root *root)
57 {
58         mutex_unlock(&root->fs_info->chunk_mutex);
59 }
60
61 static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
62 {
63         struct btrfs_device *device;
64         WARN_ON(fs_devices->opened);
65         while (!list_empty(&fs_devices->devices)) {
66                 device = list_entry(fs_devices->devices.next,
67                                     struct btrfs_device, dev_list);
68                 list_del(&device->dev_list);
69                 rcu_string_free(device->name);
70                 kfree(device);
71         }
72         kfree(fs_devices);
73 }
74
75 void btrfs_cleanup_fs_uuids(void)
76 {
77         struct btrfs_fs_devices *fs_devices;
78
79         while (!list_empty(&fs_uuids)) {
80                 fs_devices = list_entry(fs_uuids.next,
81                                         struct btrfs_fs_devices, list);
82                 list_del(&fs_devices->list);
83                 free_fs_devices(fs_devices);
84         }
85 }
86
87 static noinline struct btrfs_device *__find_device(struct list_head *head,
88                                                    u64 devid, u8 *uuid)
89 {
90         struct btrfs_device *dev;
91
92         list_for_each_entry(dev, head, dev_list) {
93                 if (dev->devid == devid &&
94                     (!uuid || !memcmp(dev->uuid, uuid, BTRFS_UUID_SIZE))) {
95                         return dev;
96                 }
97         }
98         return NULL;
99 }
100
101 static noinline struct btrfs_fs_devices *find_fsid(u8 *fsid)
102 {
103         struct btrfs_fs_devices *fs_devices;
104
105         list_for_each_entry(fs_devices, &fs_uuids, list) {
106                 if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
107                         return fs_devices;
108         }
109         return NULL;
110 }
111
112 static int
113 btrfs_get_bdev_and_sb(const char *device_path, fmode_t flags, void *holder,
114                       int flush, struct block_device **bdev,
115                       struct buffer_head **bh)
116 {
117         int ret;
118
119         *bdev = blkdev_get_by_path(device_path, flags, holder);
120
121         if (IS_ERR(*bdev)) {
122                 ret = PTR_ERR(*bdev);
123                 printk(KERN_INFO "btrfs: open %s failed\n", device_path);
124                 goto error;
125         }
126
127         if (flush)
128                 filemap_write_and_wait((*bdev)->bd_inode->i_mapping);
129         ret = set_blocksize(*bdev, 4096);
130         if (ret) {
131                 blkdev_put(*bdev, flags);
132                 goto error;
133         }
134         invalidate_bdev(*bdev);
135         *bh = btrfs_read_dev_super(*bdev);
136         if (!*bh) {
137                 ret = -EINVAL;
138                 blkdev_put(*bdev, flags);
139                 goto error;
140         }
141
142         return 0;
143
144 error:
145         *bdev = NULL;
146         *bh = NULL;
147         return ret;
148 }
149
150 static void requeue_list(struct btrfs_pending_bios *pending_bios,
151                         struct bio *head, struct bio *tail)
152 {
153
154         struct bio *old_head;
155
156         old_head = pending_bios->head;
157         pending_bios->head = head;
158         if (pending_bios->tail)
159                 tail->bi_next = old_head;
160         else
161                 pending_bios->tail = tail;
162 }
163
164 /*
165  * we try to collect pending bios for a device so we don't get a large
166  * number of procs sending bios down to the same device.  This greatly
167  * improves the schedulers ability to collect and merge the bios.
168  *
169  * But, it also turns into a long list of bios to process and that is sure
170  * to eventually make the worker thread block.  The solution here is to
171  * make some progress and then put this work struct back at the end of
172  * the list if the block device is congested.  This way, multiple devices
173  * can make progress from a single worker thread.
174  */
175 static noinline void run_scheduled_bios(struct btrfs_device *device)
176 {
177         struct bio *pending;
178         struct backing_dev_info *bdi;
179         struct btrfs_fs_info *fs_info;
180         struct btrfs_pending_bios *pending_bios;
181         struct bio *tail;
182         struct bio *cur;
183         int again = 0;
184         unsigned long num_run;
185         unsigned long batch_run = 0;
186         unsigned long limit;
187         unsigned long last_waited = 0;
188         int force_reg = 0;
189         int sync_pending = 0;
190         struct blk_plug plug;
191
192         /*
193          * this function runs all the bios we've collected for
194          * a particular device.  We don't want to wander off to
195          * another device without first sending all of these down.
196          * So, setup a plug here and finish it off before we return
197          */
198         blk_start_plug(&plug);
199
200         bdi = blk_get_backing_dev_info(device->bdev);
201         fs_info = device->dev_root->fs_info;
202         limit = btrfs_async_submit_limit(fs_info);
203         limit = limit * 2 / 3;
204
205 loop:
206         spin_lock(&device->io_lock);
207
208 loop_lock:
209         num_run = 0;
210
211         /* take all the bios off the list at once and process them
212          * later on (without the lock held).  But, remember the
213          * tail and other pointers so the bios can be properly reinserted
214          * into the list if we hit congestion
215          */
216         if (!force_reg && device->pending_sync_bios.head) {
217                 pending_bios = &device->pending_sync_bios;
218                 force_reg = 1;
219         } else {
220                 pending_bios = &device->pending_bios;
221                 force_reg = 0;
222         }
223
224         pending = pending_bios->head;
225         tail = pending_bios->tail;
226         WARN_ON(pending && !tail);
227
228         /*
229          * if pending was null this time around, no bios need processing
230          * at all and we can stop.  Otherwise it'll loop back up again
231          * and do an additional check so no bios are missed.
232          *
233          * device->running_pending is used to synchronize with the
234          * schedule_bio code.
235          */
236         if (device->pending_sync_bios.head == NULL &&
237             device->pending_bios.head == NULL) {
238                 again = 0;
239                 device->running_pending = 0;
240         } else {
241                 again = 1;
242                 device->running_pending = 1;
243         }
244
245         pending_bios->head = NULL;
246         pending_bios->tail = NULL;
247
248         spin_unlock(&device->io_lock);
249
250         while (pending) {
251
252                 rmb();
253                 /* we want to work on both lists, but do more bios on the
254                  * sync list than the regular list
255                  */
256                 if ((num_run > 32 &&
257                     pending_bios != &device->pending_sync_bios &&
258                     device->pending_sync_bios.head) ||
259                    (num_run > 64 && pending_bios == &device->pending_sync_bios &&
260                     device->pending_bios.head)) {
261                         spin_lock(&device->io_lock);
262                         requeue_list(pending_bios, pending, tail);
263                         goto loop_lock;
264                 }
265
266                 cur = pending;
267                 pending = pending->bi_next;
268                 cur->bi_next = NULL;
269
270                 if (atomic_dec_return(&fs_info->nr_async_bios) < limit &&
271                     waitqueue_active(&fs_info->async_submit_wait))
272                         wake_up(&fs_info->async_submit_wait);
273
274                 BUG_ON(atomic_read(&cur->bi_cnt) == 0);
275
276                 /*
277                  * if we're doing the sync list, record that our
278                  * plug has some sync requests on it
279                  *
280                  * If we're doing the regular list and there are
281                  * sync requests sitting around, unplug before
282                  * we add more
283                  */
284                 if (pending_bios == &device->pending_sync_bios) {
285                         sync_pending = 1;
286                 } else if (sync_pending) {
287                         blk_finish_plug(&plug);
288                         blk_start_plug(&plug);
289                         sync_pending = 0;
290                 }
291
292                 btrfsic_submit_bio(cur->bi_rw, cur);
293                 num_run++;
294                 batch_run++;
295                 if (need_resched())
296                         cond_resched();
297
298                 /*
299                  * we made progress, there is more work to do and the bdi
300                  * is now congested.  Back off and let other work structs
301                  * run instead
302                  */
303                 if (pending && bdi_write_congested(bdi) && batch_run > 8 &&
304                     fs_info->fs_devices->open_devices > 1) {
305                         struct io_context *ioc;
306
307                         ioc = current->io_context;
308
309                         /*
310                          * the main goal here is that we don't want to
311                          * block if we're going to be able to submit
312                          * more requests without blocking.
313                          *
314                          * This code does two great things, it pokes into
315                          * the elevator code from a filesystem _and_
316                          * it makes assumptions about how batching works.
317                          */
318                         if (ioc && ioc->nr_batch_requests > 0 &&
319                             time_before(jiffies, ioc->last_waited + HZ/50UL) &&
320                             (last_waited == 0 ||
321                              ioc->last_waited == last_waited)) {
322                                 /*
323                                  * we want to go through our batch of
324                                  * requests and stop.  So, we copy out
325                                  * the ioc->last_waited time and test
326                                  * against it before looping
327                                  */
328                                 last_waited = ioc->last_waited;
329                                 if (need_resched())
330                                         cond_resched();
331                                 continue;
332                         }
333                         spin_lock(&device->io_lock);
334                         requeue_list(pending_bios, pending, tail);
335                         device->running_pending = 1;
336
337                         spin_unlock(&device->io_lock);
338                         btrfs_requeue_work(&device->work);
339                         goto done;
340                 }
341                 /* unplug every 64 requests just for good measure */
342                 if (batch_run % 64 == 0) {
343                         blk_finish_plug(&plug);
344                         blk_start_plug(&plug);
345                         sync_pending = 0;
346                 }
347         }
348
349         cond_resched();
350         if (again)
351                 goto loop;
352
353         spin_lock(&device->io_lock);
354         if (device->pending_bios.head || device->pending_sync_bios.head)
355                 goto loop_lock;
356         spin_unlock(&device->io_lock);
357
358 done:
359         blk_finish_plug(&plug);
360 }
361
362 static void pending_bios_fn(struct btrfs_work *work)
363 {
364         struct btrfs_device *device;
365
366         device = container_of(work, struct btrfs_device, work);
367         run_scheduled_bios(device);
368 }
369
370 static noinline int device_list_add(const char *path,
371                            struct btrfs_super_block *disk_super,
372                            u64 devid, struct btrfs_fs_devices **fs_devices_ret)
373 {
374         struct btrfs_device *device;
375         struct btrfs_fs_devices *fs_devices;
376         struct rcu_string *name;
377         u64 found_transid = btrfs_super_generation(disk_super);
378
379         fs_devices = find_fsid(disk_super->fsid);
380         if (!fs_devices) {
381                 fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
382                 if (!fs_devices)
383                         return -ENOMEM;
384                 INIT_LIST_HEAD(&fs_devices->devices);
385                 INIT_LIST_HEAD(&fs_devices->alloc_list);
386                 list_add(&fs_devices->list, &fs_uuids);
387                 memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
388                 fs_devices->latest_devid = devid;
389                 fs_devices->latest_trans = found_transid;
390                 mutex_init(&fs_devices->device_list_mutex);
391                 device = NULL;
392         } else {
393                 device = __find_device(&fs_devices->devices, devid,
394                                        disk_super->dev_item.uuid);
395         }
396         if (!device) {
397                 if (fs_devices->opened)
398                         return -EBUSY;
399
400                 device = kzalloc(sizeof(*device), GFP_NOFS);
401                 if (!device) {
402                         /* we can safely leave the fs_devices entry around */
403                         return -ENOMEM;
404                 }
405                 device->devid = devid;
406                 device->dev_stats_valid = 0;
407                 device->work.func = pending_bios_fn;
408                 memcpy(device->uuid, disk_super->dev_item.uuid,
409                        BTRFS_UUID_SIZE);
410                 spin_lock_init(&device->io_lock);
411
412                 name = rcu_string_strdup(path, GFP_NOFS);
413                 if (!name) {
414                         kfree(device);
415                         return -ENOMEM;
416                 }
417                 rcu_assign_pointer(device->name, name);
418                 INIT_LIST_HEAD(&device->dev_alloc_list);
419
420                 /* init readahead state */
421                 spin_lock_init(&device->reada_lock);
422                 device->reada_curr_zone = NULL;
423                 atomic_set(&device->reada_in_flight, 0);
424                 device->reada_next = 0;
425                 INIT_RADIX_TREE(&device->reada_zones, GFP_NOFS & ~__GFP_WAIT);
426                 INIT_RADIX_TREE(&device->reada_extents, GFP_NOFS & ~__GFP_WAIT);
427
428                 mutex_lock(&fs_devices->device_list_mutex);
429                 list_add_rcu(&device->dev_list, &fs_devices->devices);
430                 mutex_unlock(&fs_devices->device_list_mutex);
431
432                 device->fs_devices = fs_devices;
433                 fs_devices->num_devices++;
434         } else if (!device->name || strcmp(device->name->str, path)) {
435                 name = rcu_string_strdup(path, GFP_NOFS);
436                 if (!name)
437                         return -ENOMEM;
438                 rcu_string_free(device->name);
439                 rcu_assign_pointer(device->name, name);
440                 if (device->missing) {
441                         fs_devices->missing_devices--;
442                         device->missing = 0;
443                 }
444         }
445
446         if (found_transid > fs_devices->latest_trans) {
447                 fs_devices->latest_devid = devid;
448                 fs_devices->latest_trans = found_transid;
449         }
450         *fs_devices_ret = fs_devices;
451         return 0;
452 }
453
454 static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
455 {
456         struct btrfs_fs_devices *fs_devices;
457         struct btrfs_device *device;
458         struct btrfs_device *orig_dev;
459
460         fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
461         if (!fs_devices)
462                 return ERR_PTR(-ENOMEM);
463
464         INIT_LIST_HEAD(&fs_devices->devices);
465         INIT_LIST_HEAD(&fs_devices->alloc_list);
466         INIT_LIST_HEAD(&fs_devices->list);
467         mutex_init(&fs_devices->device_list_mutex);
468         fs_devices->latest_devid = orig->latest_devid;
469         fs_devices->latest_trans = orig->latest_trans;
470         fs_devices->total_devices = orig->total_devices;
471         memcpy(fs_devices->fsid, orig->fsid, sizeof(fs_devices->fsid));
472
473         /* We have held the volume lock, it is safe to get the devices. */
474         list_for_each_entry(orig_dev, &orig->devices, dev_list) {
475                 struct rcu_string *name;
476
477                 device = kzalloc(sizeof(*device), GFP_NOFS);
478                 if (!device)
479                         goto error;
480
481                 /*
482                  * This is ok to do without rcu read locked because we hold the
483                  * uuid mutex so nothing we touch in here is going to disappear.
484                  */
485                 name = rcu_string_strdup(orig_dev->name->str, GFP_NOFS);
486                 if (!name) {
487                         kfree(device);
488                         goto error;
489                 }
490                 rcu_assign_pointer(device->name, name);
491
492                 device->devid = orig_dev->devid;
493                 device->work.func = pending_bios_fn;
494                 memcpy(device->uuid, orig_dev->uuid, sizeof(device->uuid));
495                 spin_lock_init(&device->io_lock);
496                 INIT_LIST_HEAD(&device->dev_list);
497                 INIT_LIST_HEAD(&device->dev_alloc_list);
498
499                 list_add(&device->dev_list, &fs_devices->devices);
500                 device->fs_devices = fs_devices;
501                 fs_devices->num_devices++;
502         }
503         return fs_devices;
504 error:
505         free_fs_devices(fs_devices);
506         return ERR_PTR(-ENOMEM);
507 }
508
509 void btrfs_close_extra_devices(struct btrfs_fs_info *fs_info,
510                                struct btrfs_fs_devices *fs_devices, int step)
511 {
512         struct btrfs_device *device, *next;
513
514         struct block_device *latest_bdev = NULL;
515         u64 latest_devid = 0;
516         u64 latest_transid = 0;
517
518         mutex_lock(&uuid_mutex);
519 again:
520         /* This is the initialized path, it is safe to release the devices. */
521         list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
522                 if (device->in_fs_metadata) {
523                         if (!device->is_tgtdev_for_dev_replace &&
524                             (!latest_transid ||
525                              device->generation > latest_transid)) {
526                                 latest_devid = device->devid;
527                                 latest_transid = device->generation;
528                                 latest_bdev = device->bdev;
529                         }
530                         continue;
531                 }
532
533                 if (device->devid == BTRFS_DEV_REPLACE_DEVID) {
534                         /*
535                          * In the first step, keep the device which has
536                          * the correct fsid and the devid that is used
537                          * for the dev_replace procedure.
538                          * In the second step, the dev_replace state is
539                          * read from the device tree and it is known
540                          * whether the procedure is really active or
541                          * not, which means whether this device is
542                          * used or whether it should be removed.
543                          */
544                         if (step == 0 || device->is_tgtdev_for_dev_replace) {
545                                 continue;
546                         }
547                 }
548                 if (device->bdev) {
549                         blkdev_put(device->bdev, device->mode);
550                         device->bdev = NULL;
551                         fs_devices->open_devices--;
552                 }
553                 if (device->writeable) {
554                         list_del_init(&device->dev_alloc_list);
555                         device->writeable = 0;
556                         if (!device->is_tgtdev_for_dev_replace)
557                                 fs_devices->rw_devices--;
558                 }
559                 list_del_init(&device->dev_list);
560                 fs_devices->num_devices--;
561                 rcu_string_free(device->name);
562                 kfree(device);
563         }
564
565         if (fs_devices->seed) {
566                 fs_devices = fs_devices->seed;
567                 goto again;
568         }
569
570         fs_devices->latest_bdev = latest_bdev;
571         fs_devices->latest_devid = latest_devid;
572         fs_devices->latest_trans = latest_transid;
573
574         mutex_unlock(&uuid_mutex);
575 }
576
577 static void __free_device(struct work_struct *work)
578 {
579         struct btrfs_device *device;
580
581         device = container_of(work, struct btrfs_device, rcu_work);
582
583         if (device->bdev)
584                 blkdev_put(device->bdev, device->mode);
585
586         rcu_string_free(device->name);
587         kfree(device);
588 }
589
590 static void free_device(struct rcu_head *head)
591 {
592         struct btrfs_device *device;
593
594         device = container_of(head, struct btrfs_device, rcu);
595
596         INIT_WORK(&device->rcu_work, __free_device);
597         schedule_work(&device->rcu_work);
598 }
599
600 static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
601 {
602         struct btrfs_device *device;
603
604         if (--fs_devices->opened > 0)
605                 return 0;
606
607         mutex_lock(&fs_devices->device_list_mutex);
608         list_for_each_entry(device, &fs_devices->devices, dev_list) {
609                 struct btrfs_device *new_device;
610                 struct rcu_string *name;
611
612                 if (device->bdev)
613                         fs_devices->open_devices--;
614
615                 if (device->writeable && !device->is_tgtdev_for_dev_replace) {
616                         list_del_init(&device->dev_alloc_list);
617                         fs_devices->rw_devices--;
618                 }
619
620                 if (device->can_discard)
621                         fs_devices->num_can_discard--;
622
623                 new_device = kmalloc(sizeof(*new_device), GFP_NOFS);
624                 BUG_ON(!new_device); /* -ENOMEM */
625                 memcpy(new_device, device, sizeof(*new_device));
626
627                 /* Safe because we are under uuid_mutex */
628                 if (device->name) {
629                         name = rcu_string_strdup(device->name->str, GFP_NOFS);
630                         BUG_ON(device->name && !name); /* -ENOMEM */
631                         rcu_assign_pointer(new_device->name, name);
632                 }
633                 new_device->bdev = NULL;
634                 new_device->writeable = 0;
635                 new_device->in_fs_metadata = 0;
636                 new_device->can_discard = 0;
637                 list_replace_rcu(&device->dev_list, &new_device->dev_list);
638
639                 call_rcu(&device->rcu, free_device);
640         }
641         mutex_unlock(&fs_devices->device_list_mutex);
642
643         WARN_ON(fs_devices->open_devices);
644         WARN_ON(fs_devices->rw_devices);
645         fs_devices->opened = 0;
646         fs_devices->seeding = 0;
647
648         return 0;
649 }
650
651 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
652 {
653         struct btrfs_fs_devices *seed_devices = NULL;
654         int ret;
655
656         mutex_lock(&uuid_mutex);
657         ret = __btrfs_close_devices(fs_devices);
658         if (!fs_devices->opened) {
659                 seed_devices = fs_devices->seed;
660                 fs_devices->seed = NULL;
661         }
662         mutex_unlock(&uuid_mutex);
663
664         while (seed_devices) {
665                 fs_devices = seed_devices;
666                 seed_devices = fs_devices->seed;
667                 __btrfs_close_devices(fs_devices);
668                 free_fs_devices(fs_devices);
669         }
670         return ret;
671 }
672
673 static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
674                                 fmode_t flags, void *holder)
675 {
676         struct request_queue *q;
677         struct block_device *bdev;
678         struct list_head *head = &fs_devices->devices;
679         struct btrfs_device *device;
680         struct block_device *latest_bdev = NULL;
681         struct buffer_head *bh;
682         struct btrfs_super_block *disk_super;
683         u64 latest_devid = 0;
684         u64 latest_transid = 0;
685         u64 devid;
686         int seeding = 1;
687         int ret = 0;
688
689         flags |= FMODE_EXCL;
690
691         list_for_each_entry(device, head, dev_list) {
692                 if (device->bdev)
693                         continue;
694                 if (!device->name)
695                         continue;
696
697                 ret = btrfs_get_bdev_and_sb(device->name->str, flags, holder, 1,
698                                             &bdev, &bh);
699                 if (ret)
700                         continue;
701
702                 disk_super = (struct btrfs_super_block *)bh->b_data;
703                 devid = btrfs_stack_device_id(&disk_super->dev_item);
704                 if (devid != device->devid)
705                         goto error_brelse;
706
707                 if (memcmp(device->uuid, disk_super->dev_item.uuid,
708                            BTRFS_UUID_SIZE))
709                         goto error_brelse;
710
711                 device->generation = btrfs_super_generation(disk_super);
712                 if (!latest_transid || device->generation > latest_transid) {
713                         latest_devid = devid;
714                         latest_transid = device->generation;
715                         latest_bdev = bdev;
716                 }
717
718                 if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING) {
719                         device->writeable = 0;
720                 } else {
721                         device->writeable = !bdev_read_only(bdev);
722                         seeding = 0;
723                 }
724
725                 q = bdev_get_queue(bdev);
726                 if (blk_queue_discard(q)) {
727                         device->can_discard = 1;
728                         fs_devices->num_can_discard++;
729                 }
730
731                 device->bdev = bdev;
732                 device->in_fs_metadata = 0;
733                 device->mode = flags;
734
735                 if (!blk_queue_nonrot(bdev_get_queue(bdev)))
736                         fs_devices->rotating = 1;
737
738                 fs_devices->open_devices++;
739                 if (device->writeable && !device->is_tgtdev_for_dev_replace) {
740                         fs_devices->rw_devices++;
741                         list_add(&device->dev_alloc_list,
742                                  &fs_devices->alloc_list);
743                 }
744                 brelse(bh);
745                 continue;
746
747 error_brelse:
748                 brelse(bh);
749                 blkdev_put(bdev, flags);
750                 continue;
751         }
752         if (fs_devices->open_devices == 0) {
753                 ret = -EINVAL;
754                 goto out;
755         }
756         fs_devices->seeding = seeding;
757         fs_devices->opened = 1;
758         fs_devices->latest_bdev = latest_bdev;
759         fs_devices->latest_devid = latest_devid;
760         fs_devices->latest_trans = latest_transid;
761         fs_devices->total_rw_bytes = 0;
762 out:
763         return ret;
764 }
765
766 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
767                        fmode_t flags, void *holder)
768 {
769         int ret;
770
771         mutex_lock(&uuid_mutex);
772         if (fs_devices->opened) {
773                 fs_devices->opened++;
774                 ret = 0;
775         } else {
776                 ret = __btrfs_open_devices(fs_devices, flags, holder);
777         }
778         mutex_unlock(&uuid_mutex);
779         return ret;
780 }
781
782 int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
783                           struct btrfs_fs_devices **fs_devices_ret)
784 {
785         struct btrfs_super_block *disk_super;
786         struct block_device *bdev;
787         struct buffer_head *bh;
788         int ret;
789         u64 devid;
790         u64 transid;
791         u64 total_devices;
792
793         flags |= FMODE_EXCL;
794         mutex_lock(&uuid_mutex);
795         ret = btrfs_get_bdev_and_sb(path, flags, holder, 0, &bdev, &bh);
796         if (ret)
797                 goto error;
798         disk_super = (struct btrfs_super_block *)bh->b_data;
799         devid = btrfs_stack_device_id(&disk_super->dev_item);
800         transid = btrfs_super_generation(disk_super);
801         total_devices = btrfs_super_num_devices(disk_super);
802         if (disk_super->label[0]) {
803                 if (disk_super->label[BTRFS_LABEL_SIZE - 1])
804                         disk_super->label[BTRFS_LABEL_SIZE - 1] = '\0';
805                 printk(KERN_INFO "device label %s ", disk_super->label);
806         } else {
807                 printk(KERN_INFO "device fsid %pU ", disk_super->fsid);
808         }
809         printk(KERN_CONT "devid %llu transid %llu %s\n",
810                (unsigned long long)devid, (unsigned long long)transid, path);
811         ret = device_list_add(path, disk_super, devid, fs_devices_ret);
812         if (!ret && fs_devices_ret)
813                 (*fs_devices_ret)->total_devices = total_devices;
814         brelse(bh);
815         blkdev_put(bdev, flags);
816 error:
817         mutex_unlock(&uuid_mutex);
818         return ret;
819 }
820
821 /* helper to account the used device space in the range */
822 int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
823                                    u64 end, u64 *length)
824 {
825         struct btrfs_key key;
826         struct btrfs_root *root = device->dev_root;
827         struct btrfs_dev_extent *dev_extent;
828         struct btrfs_path *path;
829         u64 extent_end;
830         int ret;
831         int slot;
832         struct extent_buffer *l;
833
834         *length = 0;
835
836         if (start >= device->total_bytes || device->is_tgtdev_for_dev_replace)
837                 return 0;
838
839         path = btrfs_alloc_path();
840         if (!path)
841                 return -ENOMEM;
842         path->reada = 2;
843
844         key.objectid = device->devid;
845         key.offset = start;
846         key.type = BTRFS_DEV_EXTENT_KEY;
847
848         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
849         if (ret < 0)
850                 goto out;
851         if (ret > 0) {
852                 ret = btrfs_previous_item(root, path, key.objectid, key.type);
853                 if (ret < 0)
854                         goto out;
855         }
856
857         while (1) {
858                 l = path->nodes[0];
859                 slot = path->slots[0];
860                 if (slot >= btrfs_header_nritems(l)) {
861                         ret = btrfs_next_leaf(root, path);
862                         if (ret == 0)
863                                 continue;
864                         if (ret < 0)
865                                 goto out;
866
867                         break;
868                 }
869                 btrfs_item_key_to_cpu(l, &key, slot);
870
871                 if (key.objectid < device->devid)
872                         goto next;
873
874                 if (key.objectid > device->devid)
875                         break;
876
877                 if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
878                         goto next;
879
880                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
881                 extent_end = key.offset + btrfs_dev_extent_length(l,
882                                                                   dev_extent);
883                 if (key.offset <= start && extent_end > end) {
884                         *length = end - start + 1;
885                         break;
886                 } else if (key.offset <= start && extent_end > start)
887                         *length += extent_end - start;
888                 else if (key.offset > start && extent_end <= end)
889                         *length += extent_end - key.offset;
890                 else if (key.offset > start && key.offset <= end) {
891                         *length += end - key.offset + 1;
892                         break;
893                 } else if (key.offset > end)
894                         break;
895
896 next:
897                 path->slots[0]++;
898         }
899         ret = 0;
900 out:
901         btrfs_free_path(path);
902         return ret;
903 }
904
905 /*
906  * find_free_dev_extent - find free space in the specified device
907  * @device:     the device which we search the free space in
908  * @num_bytes:  the size of the free space that we need
909  * @start:      store the start of the free space.
910  * @len:        the size of the free space. that we find, or the size of the max
911  *              free space if we don't find suitable free space
912  *
913  * this uses a pretty simple search, the expectation is that it is
914  * called very infrequently and that a given device has a small number
915  * of extents
916  *
917  * @start is used to store the start of the free space if we find. But if we
918  * don't find suitable free space, it will be used to store the start position
919  * of the max free space.
920  *
921  * @len is used to store the size of the free space that we find.
922  * But if we don't find suitable free space, it is used to store the size of
923  * the max free space.
924  */
925 int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes,
926                          u64 *start, u64 *len)
927 {
928         struct btrfs_key key;
929         struct btrfs_root *root = device->dev_root;
930         struct btrfs_dev_extent *dev_extent;
931         struct btrfs_path *path;
932         u64 hole_size;
933         u64 max_hole_start;
934         u64 max_hole_size;
935         u64 extent_end;
936         u64 search_start;
937         u64 search_end = device->total_bytes;
938         int ret;
939         int slot;
940         struct extent_buffer *l;
941
942         /* FIXME use last free of some kind */
943
944         /* we don't want to overwrite the superblock on the drive,
945          * so we make sure to start at an offset of at least 1MB
946          */
947         search_start = max(root->fs_info->alloc_start, 1024ull * 1024);
948
949         max_hole_start = search_start;
950         max_hole_size = 0;
951         hole_size = 0;
952
953         if (search_start >= search_end || device->is_tgtdev_for_dev_replace) {
954                 ret = -ENOSPC;
955                 goto error;
956         }
957
958         path = btrfs_alloc_path();
959         if (!path) {
960                 ret = -ENOMEM;
961                 goto error;
962         }
963         path->reada = 2;
964
965         key.objectid = device->devid;
966         key.offset = search_start;
967         key.type = BTRFS_DEV_EXTENT_KEY;
968
969         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
970         if (ret < 0)
971                 goto out;
972         if (ret > 0) {
973                 ret = btrfs_previous_item(root, path, key.objectid, key.type);
974                 if (ret < 0)
975                         goto out;
976         }
977
978         while (1) {
979                 l = path->nodes[0];
980                 slot = path->slots[0];
981                 if (slot >= btrfs_header_nritems(l)) {
982                         ret = btrfs_next_leaf(root, path);
983                         if (ret == 0)
984                                 continue;
985                         if (ret < 0)
986                                 goto out;
987
988                         break;
989                 }
990                 btrfs_item_key_to_cpu(l, &key, slot);
991
992                 if (key.objectid < device->devid)
993                         goto next;
994
995                 if (key.objectid > device->devid)
996                         break;
997
998                 if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
999                         goto next;
1000
1001                 if (key.offset > search_start) {
1002                         hole_size = key.offset - search_start;
1003
1004                         if (hole_size > max_hole_size) {
1005                                 max_hole_start = search_start;
1006                                 max_hole_size = hole_size;
1007                         }
1008
1009                         /*
1010                          * If this free space is greater than which we need,
1011                          * it must be the max free space that we have found
1012                          * until now, so max_hole_start must point to the start
1013                          * of this free space and the length of this free space
1014                          * is stored in max_hole_size. Thus, we return
1015                          * max_hole_start and max_hole_size and go back to the
1016                          * caller.
1017                          */
1018                         if (hole_size >= num_bytes) {
1019                                 ret = 0;
1020                                 goto out;
1021                         }
1022                 }
1023
1024                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
1025                 extent_end = key.offset + btrfs_dev_extent_length(l,
1026                                                                   dev_extent);
1027                 if (extent_end > search_start)
1028                         search_start = extent_end;
1029 next:
1030                 path->slots[0]++;
1031                 cond_resched();
1032         }
1033
1034         /*
1035          * At this point, search_start should be the end of
1036          * allocated dev extents, and when shrinking the device,
1037          * search_end may be smaller than search_start.
1038          */
1039         if (search_end > search_start)
1040                 hole_size = search_end - search_start;
1041
1042         if (hole_size > max_hole_size) {
1043                 max_hole_start = search_start;
1044                 max_hole_size = hole_size;
1045         }
1046
1047         /* See above. */
1048         if (hole_size < num_bytes)
1049                 ret = -ENOSPC;
1050         else
1051                 ret = 0;
1052
1053 out:
1054         btrfs_free_path(path);
1055 error:
1056         *start = max_hole_start;
1057         if (len)
1058                 *len = max_hole_size;
1059         return ret;
1060 }
1061
1062 static int btrfs_free_dev_extent(struct btrfs_trans_handle *trans,
1063                           struct btrfs_device *device,
1064                           u64 start)
1065 {
1066         int ret;
1067         struct btrfs_path *path;
1068         struct btrfs_root *root = device->dev_root;
1069         struct btrfs_key key;
1070         struct btrfs_key found_key;
1071         struct extent_buffer *leaf = NULL;
1072         struct btrfs_dev_extent *extent = NULL;
1073
1074         path = btrfs_alloc_path();
1075         if (!path)
1076                 return -ENOMEM;
1077
1078         key.objectid = device->devid;
1079         key.offset = start;
1080         key.type = BTRFS_DEV_EXTENT_KEY;
1081 again:
1082         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1083         if (ret > 0) {
1084                 ret = btrfs_previous_item(root, path, key.objectid,
1085                                           BTRFS_DEV_EXTENT_KEY);
1086                 if (ret)
1087                         goto out;
1088                 leaf = path->nodes[0];
1089                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1090                 extent = btrfs_item_ptr(leaf, path->slots[0],
1091                                         struct btrfs_dev_extent);
1092                 BUG_ON(found_key.offset > start || found_key.offset +
1093                        btrfs_dev_extent_length(leaf, extent) < start);
1094                 key = found_key;
1095                 btrfs_release_path(path);
1096                 goto again;
1097         } else if (ret == 0) {
1098                 leaf = path->nodes[0];
1099                 extent = btrfs_item_ptr(leaf, path->slots[0],
1100                                         struct btrfs_dev_extent);
1101         } else {
1102                 btrfs_error(root->fs_info, ret, "Slot search failed");
1103                 goto out;
1104         }
1105
1106         if (device->bytes_used > 0) {
1107                 u64 len = btrfs_dev_extent_length(leaf, extent);
1108                 device->bytes_used -= len;
1109                 spin_lock(&root->fs_info->free_chunk_lock);
1110                 root->fs_info->free_chunk_space += len;
1111                 spin_unlock(&root->fs_info->free_chunk_lock);
1112         }
1113         ret = btrfs_del_item(trans, root, path);
1114         if (ret) {
1115                 btrfs_error(root->fs_info, ret,
1116                             "Failed to remove dev extent item");
1117         }
1118 out:
1119         btrfs_free_path(path);
1120         return ret;
1121 }
1122
1123 int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
1124                            struct btrfs_device *device,
1125                            u64 chunk_tree, u64 chunk_objectid,
1126                            u64 chunk_offset, u64 start, u64 num_bytes)
1127 {
1128         int ret;
1129         struct btrfs_path *path;
1130         struct btrfs_root *root = device->dev_root;
1131         struct btrfs_dev_extent *extent;
1132         struct extent_buffer *leaf;
1133         struct btrfs_key key;
1134
1135         WARN_ON(!device->in_fs_metadata);
1136         WARN_ON(device->is_tgtdev_for_dev_replace);
1137         path = btrfs_alloc_path();
1138         if (!path)
1139                 return -ENOMEM;
1140
1141         key.objectid = device->devid;
1142         key.offset = start;
1143         key.type = BTRFS_DEV_EXTENT_KEY;
1144         ret = btrfs_insert_empty_item(trans, root, path, &key,
1145                                       sizeof(*extent));
1146         if (ret)
1147                 goto out;
1148
1149         leaf = path->nodes[0];
1150         extent = btrfs_item_ptr(leaf, path->slots[0],
1151                                 struct btrfs_dev_extent);
1152         btrfs_set_dev_extent_chunk_tree(leaf, extent, chunk_tree);
1153         btrfs_set_dev_extent_chunk_objectid(leaf, extent, chunk_objectid);
1154         btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);
1155
1156         write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
1157                     (unsigned long)btrfs_dev_extent_chunk_tree_uuid(extent),
1158                     BTRFS_UUID_SIZE);
1159
1160         btrfs_set_dev_extent_length(leaf, extent, num_bytes);
1161         btrfs_mark_buffer_dirty(leaf);
1162 out:
1163         btrfs_free_path(path);
1164         return ret;
1165 }
1166
1167 static noinline int find_next_chunk(struct btrfs_root *root,
1168                                     u64 objectid, u64 *offset)
1169 {
1170         struct btrfs_path *path;
1171         int ret;
1172         struct btrfs_key key;
1173         struct btrfs_chunk *chunk;
1174         struct btrfs_key found_key;
1175
1176         path = btrfs_alloc_path();
1177         if (!path)
1178                 return -ENOMEM;
1179
1180         key.objectid = objectid;
1181         key.offset = (u64)-1;
1182         key.type = BTRFS_CHUNK_ITEM_KEY;
1183
1184         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1185         if (ret < 0)
1186                 goto error;
1187
1188         BUG_ON(ret == 0); /* Corruption */
1189
1190         ret = btrfs_previous_item(root, path, 0, BTRFS_CHUNK_ITEM_KEY);
1191         if (ret) {
1192                 *offset = 0;
1193         } else {
1194                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
1195                                       path->slots[0]);
1196                 if (found_key.objectid != objectid)
1197                         *offset = 0;
1198                 else {
1199                         chunk = btrfs_item_ptr(path->nodes[0], path->slots[0],
1200                                                struct btrfs_chunk);
1201                         *offset = found_key.offset +
1202                                 btrfs_chunk_length(path->nodes[0], chunk);
1203                 }
1204         }
1205         ret = 0;
1206 error:
1207         btrfs_free_path(path);
1208         return ret;
1209 }
1210
1211 static noinline int find_next_devid(struct btrfs_root *root, u64 *objectid)
1212 {
1213         int ret;
1214         struct btrfs_key key;
1215         struct btrfs_key found_key;
1216         struct btrfs_path *path;
1217
1218         root = root->fs_info->chunk_root;
1219
1220         path = btrfs_alloc_path();
1221         if (!path)
1222                 return -ENOMEM;
1223
1224         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1225         key.type = BTRFS_DEV_ITEM_KEY;
1226         key.offset = (u64)-1;
1227
1228         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1229         if (ret < 0)
1230                 goto error;
1231
1232         BUG_ON(ret == 0); /* Corruption */
1233
1234         ret = btrfs_previous_item(root, path, BTRFS_DEV_ITEMS_OBJECTID,
1235                                   BTRFS_DEV_ITEM_KEY);
1236         if (ret) {
1237                 *objectid = 1;
1238         } else {
1239                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
1240                                       path->slots[0]);
1241                 *objectid = found_key.offset + 1;
1242         }
1243         ret = 0;
1244 error:
1245         btrfs_free_path(path);
1246         return ret;
1247 }
1248
1249 /*
1250  * the device information is stored in the chunk root
1251  * the btrfs_device struct should be fully filled in
1252  */
1253 int btrfs_add_device(struct btrfs_trans_handle *trans,
1254                      struct btrfs_root *root,
1255                      struct btrfs_device *device)
1256 {
1257         int ret;
1258         struct btrfs_path *path;
1259         struct btrfs_dev_item *dev_item;
1260         struct extent_buffer *leaf;
1261         struct btrfs_key key;
1262         unsigned long ptr;
1263
1264         root = root->fs_info->chunk_root;
1265
1266         path = btrfs_alloc_path();
1267         if (!path)
1268                 return -ENOMEM;
1269
1270         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1271         key.type = BTRFS_DEV_ITEM_KEY;
1272         key.offset = device->devid;
1273
1274         ret = btrfs_insert_empty_item(trans, root, path, &key,
1275                                       sizeof(*dev_item));
1276         if (ret)
1277                 goto out;
1278
1279         leaf = path->nodes[0];
1280         dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
1281
1282         btrfs_set_device_id(leaf, dev_item, device->devid);
1283         btrfs_set_device_generation(leaf, dev_item, 0);
1284         btrfs_set_device_type(leaf, dev_item, device->type);
1285         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
1286         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
1287         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
1288         btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
1289         btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
1290         btrfs_set_device_group(leaf, dev_item, 0);
1291         btrfs_set_device_seek_speed(leaf, dev_item, 0);
1292         btrfs_set_device_bandwidth(leaf, dev_item, 0);
1293         btrfs_set_device_start_offset(leaf, dev_item, 0);
1294
1295         ptr = (unsigned long)btrfs_device_uuid(dev_item);
1296         write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
1297         ptr = (unsigned long)btrfs_device_fsid(dev_item);
1298         write_extent_buffer(leaf, root->fs_info->fsid, ptr, BTRFS_UUID_SIZE);
1299         btrfs_mark_buffer_dirty(leaf);
1300
1301         ret = 0;
1302 out:
1303         btrfs_free_path(path);
1304         return ret;
1305 }
1306
1307 static int btrfs_rm_dev_item(struct btrfs_root *root,
1308                              struct btrfs_device *device)
1309 {
1310         int ret;
1311         struct btrfs_path *path;
1312         struct btrfs_key key;
1313         struct btrfs_trans_handle *trans;
1314
1315         root = root->fs_info->chunk_root;
1316
1317         path = btrfs_alloc_path();
1318         if (!path)
1319                 return -ENOMEM;
1320
1321         trans = btrfs_start_transaction(root, 0);
1322         if (IS_ERR(trans)) {
1323                 btrfs_free_path(path);
1324                 return PTR_ERR(trans);
1325         }
1326         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1327         key.type = BTRFS_DEV_ITEM_KEY;
1328         key.offset = device->devid;
1329         lock_chunks(root);
1330
1331         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1332         if (ret < 0)
1333                 goto out;
1334
1335         if (ret > 0) {
1336                 ret = -ENOENT;
1337                 goto out;
1338         }
1339
1340         ret = btrfs_del_item(trans, root, path);
1341         if (ret)
1342                 goto out;
1343 out:
1344         btrfs_free_path(path);
1345         unlock_chunks(root);
1346         btrfs_commit_transaction(trans, root);
1347         return ret;
1348 }
1349
1350 int btrfs_rm_device(struct btrfs_root *root, char *device_path)
1351 {
1352         struct btrfs_device *device;
1353         struct btrfs_device *next_device;
1354         struct block_device *bdev;
1355         struct buffer_head *bh = NULL;
1356         struct btrfs_super_block *disk_super;
1357         struct btrfs_fs_devices *cur_devices;
1358         u64 all_avail;
1359         u64 devid;
1360         u64 num_devices;
1361         u8 *dev_uuid;
1362         int ret = 0;
1363         bool clear_super = false;
1364
1365         mutex_lock(&uuid_mutex);
1366
1367         all_avail = root->fs_info->avail_data_alloc_bits |
1368                 root->fs_info->avail_system_alloc_bits |
1369                 root->fs_info->avail_metadata_alloc_bits;
1370
1371         num_devices = root->fs_info->fs_devices->num_devices;
1372         btrfs_dev_replace_lock(&root->fs_info->dev_replace);
1373         if (btrfs_dev_replace_is_ongoing(&root->fs_info->dev_replace)) {
1374                 WARN_ON(num_devices < 1);
1375                 num_devices--;
1376         }
1377         btrfs_dev_replace_unlock(&root->fs_info->dev_replace);
1378
1379         if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) && num_devices <= 4) {
1380                 printk(KERN_ERR "btrfs: unable to go below four devices "
1381                        "on raid10\n");
1382                 ret = -EINVAL;
1383                 goto out;
1384         }
1385
1386         if ((all_avail & BTRFS_BLOCK_GROUP_RAID1) && num_devices <= 2) {
1387                 printk(KERN_ERR "btrfs: unable to go below two "
1388                        "devices on raid1\n");
1389                 ret = -EINVAL;
1390                 goto out;
1391         }
1392
1393         if (strcmp(device_path, "missing") == 0) {
1394                 struct list_head *devices;
1395                 struct btrfs_device *tmp;
1396
1397                 device = NULL;
1398                 devices = &root->fs_info->fs_devices->devices;
1399                 /*
1400                  * It is safe to read the devices since the volume_mutex
1401                  * is held.
1402                  */
1403                 list_for_each_entry(tmp, devices, dev_list) {
1404                         if (tmp->in_fs_metadata &&
1405                             !tmp->is_tgtdev_for_dev_replace &&
1406                             !tmp->bdev) {
1407                                 device = tmp;
1408                                 break;
1409                         }
1410                 }
1411                 bdev = NULL;
1412                 bh = NULL;
1413                 disk_super = NULL;
1414                 if (!device) {
1415                         printk(KERN_ERR "btrfs: no missing devices found to "
1416                                "remove\n");
1417                         goto out;
1418                 }
1419         } else {
1420                 ret = btrfs_get_bdev_and_sb(device_path,
1421                                             FMODE_READ | FMODE_EXCL,
1422                                             root->fs_info->bdev_holder, 0,
1423                                             &bdev, &bh);
1424                 if (ret)
1425                         goto out;
1426                 disk_super = (struct btrfs_super_block *)bh->b_data;
1427                 devid = btrfs_stack_device_id(&disk_super->dev_item);
1428                 dev_uuid = disk_super->dev_item.uuid;
1429                 device = btrfs_find_device(root->fs_info, devid, dev_uuid,
1430                                            disk_super->fsid);
1431                 if (!device) {
1432                         ret = -ENOENT;
1433                         goto error_brelse;
1434                 }
1435         }
1436
1437         if (device->is_tgtdev_for_dev_replace) {
1438                 pr_err("btrfs: unable to remove the dev_replace target dev\n");
1439                 ret = -EINVAL;
1440                 goto error_brelse;
1441         }
1442
1443         if (device->writeable && root->fs_info->fs_devices->rw_devices == 1) {
1444                 printk(KERN_ERR "btrfs: unable to remove the only writeable "
1445                        "device\n");
1446                 ret = -EINVAL;
1447                 goto error_brelse;
1448         }
1449
1450         if (device->writeable) {
1451                 lock_chunks(root);
1452                 list_del_init(&device->dev_alloc_list);
1453                 unlock_chunks(root);
1454                 root->fs_info->fs_devices->rw_devices--;
1455                 clear_super = true;
1456         }
1457
1458         ret = btrfs_shrink_device(device, 0);
1459         if (ret)
1460                 goto error_undo;
1461
1462         /*
1463          * TODO: the superblock still includes this device in its num_devices
1464          * counter although write_all_supers() is not locked out. This
1465          * could give a filesystem state which requires a degraded mount.
1466          */
1467         ret = btrfs_rm_dev_item(root->fs_info->chunk_root, device);
1468         if (ret)
1469                 goto error_undo;
1470
1471         spin_lock(&root->fs_info->free_chunk_lock);
1472         root->fs_info->free_chunk_space = device->total_bytes -
1473                 device->bytes_used;
1474         spin_unlock(&root->fs_info->free_chunk_lock);
1475
1476         device->in_fs_metadata = 0;
1477         btrfs_scrub_cancel_dev(root->fs_info, device);
1478
1479         /*
1480          * the device list mutex makes sure that we don't change
1481          * the device list while someone else is writing out all
1482          * the device supers.
1483          */
1484
1485         cur_devices = device->fs_devices;
1486         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1487         list_del_rcu(&device->dev_list);
1488
1489         device->fs_devices->num_devices--;
1490         device->fs_devices->total_devices--;
1491
1492         if (device->missing)
1493                 root->fs_info->fs_devices->missing_devices--;
1494
1495         next_device = list_entry(root->fs_info->fs_devices->devices.next,
1496                                  struct btrfs_device, dev_list);
1497         if (device->bdev == root->fs_info->sb->s_bdev)
1498                 root->fs_info->sb->s_bdev = next_device->bdev;
1499         if (device->bdev == root->fs_info->fs_devices->latest_bdev)
1500                 root->fs_info->fs_devices->latest_bdev = next_device->bdev;
1501
1502         if (device->bdev)
1503                 device->fs_devices->open_devices--;
1504
1505         call_rcu(&device->rcu, free_device);
1506         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1507
1508         num_devices = btrfs_super_num_devices(root->fs_info->super_copy) - 1;
1509         btrfs_set_super_num_devices(root->fs_info->super_copy, num_devices);
1510
1511         if (cur_devices->open_devices == 0) {
1512                 struct btrfs_fs_devices *fs_devices;
1513                 fs_devices = root->fs_info->fs_devices;
1514                 while (fs_devices) {
1515                         if (fs_devices->seed == cur_devices)
1516                                 break;
1517                         fs_devices = fs_devices->seed;
1518                 }
1519                 fs_devices->seed = cur_devices->seed;
1520                 cur_devices->seed = NULL;
1521                 lock_chunks(root);
1522                 __btrfs_close_devices(cur_devices);
1523                 unlock_chunks(root);
1524                 free_fs_devices(cur_devices);
1525         }
1526
1527         root->fs_info->num_tolerated_disk_barrier_failures =
1528                 btrfs_calc_num_tolerated_disk_barrier_failures(root->fs_info);
1529
1530         /*
1531          * at this point, the device is zero sized.  We want to
1532          * remove it from the devices list and zero out the old super
1533          */
1534         if (clear_super && disk_super) {
1535                 /* make sure this device isn't detected as part of
1536                  * the FS anymore
1537                  */
1538                 memset(&disk_super->magic, 0, sizeof(disk_super->magic));
1539                 set_buffer_dirty(bh);
1540                 sync_dirty_buffer(bh);
1541         }
1542
1543         ret = 0;
1544
1545 error_brelse:
1546         brelse(bh);
1547 error_close:
1548         if (bdev)
1549                 blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
1550 out:
1551         mutex_unlock(&uuid_mutex);
1552         return ret;
1553 error_undo:
1554         if (device->writeable) {
1555                 lock_chunks(root);
1556                 list_add(&device->dev_alloc_list,
1557                          &root->fs_info->fs_devices->alloc_list);
1558                 unlock_chunks(root);
1559                 root->fs_info->fs_devices->rw_devices++;
1560         }
1561         goto error_brelse;
1562 }
1563
1564 void btrfs_rm_dev_replace_srcdev(struct btrfs_fs_info *fs_info,
1565                                  struct btrfs_device *srcdev)
1566 {
1567         WARN_ON(!mutex_is_locked(&fs_info->fs_devices->device_list_mutex));
1568         list_del_rcu(&srcdev->dev_list);
1569         list_del_rcu(&srcdev->dev_alloc_list);
1570         fs_info->fs_devices->num_devices--;
1571         if (srcdev->missing) {
1572                 fs_info->fs_devices->missing_devices--;
1573                 fs_info->fs_devices->rw_devices++;
1574         }
1575         if (srcdev->can_discard)
1576                 fs_info->fs_devices->num_can_discard--;
1577         if (srcdev->bdev)
1578                 fs_info->fs_devices->open_devices--;
1579
1580         call_rcu(&srcdev->rcu, free_device);
1581 }
1582
1583 void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
1584                                       struct btrfs_device *tgtdev)
1585 {
1586         struct btrfs_device *next_device;
1587
1588         WARN_ON(!tgtdev);
1589         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1590         if (tgtdev->bdev) {
1591                 btrfs_scratch_superblock(tgtdev);
1592                 fs_info->fs_devices->open_devices--;
1593         }
1594         fs_info->fs_devices->num_devices--;
1595         if (tgtdev->can_discard)
1596                 fs_info->fs_devices->num_can_discard++;
1597
1598         next_device = list_entry(fs_info->fs_devices->devices.next,
1599                                  struct btrfs_device, dev_list);
1600         if (tgtdev->bdev == fs_info->sb->s_bdev)
1601                 fs_info->sb->s_bdev = next_device->bdev;
1602         if (tgtdev->bdev == fs_info->fs_devices->latest_bdev)
1603                 fs_info->fs_devices->latest_bdev = next_device->bdev;
1604         list_del_rcu(&tgtdev->dev_list);
1605
1606         call_rcu(&tgtdev->rcu, free_device);
1607
1608         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1609 }
1610
1611 int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
1612                               struct btrfs_device **device)
1613 {
1614         int ret = 0;
1615         struct btrfs_super_block *disk_super;
1616         u64 devid;
1617         u8 *dev_uuid;
1618         struct block_device *bdev;
1619         struct buffer_head *bh;
1620
1621         *device = NULL;
1622         ret = btrfs_get_bdev_and_sb(device_path, FMODE_READ,
1623                                     root->fs_info->bdev_holder, 0, &bdev, &bh);
1624         if (ret)
1625                 return ret;
1626         disk_super = (struct btrfs_super_block *)bh->b_data;
1627         devid = btrfs_stack_device_id(&disk_super->dev_item);
1628         dev_uuid = disk_super->dev_item.uuid;
1629         *device = btrfs_find_device(root->fs_info, devid, dev_uuid,
1630                                     disk_super->fsid);
1631         brelse(bh);
1632         if (!*device)
1633                 ret = -ENOENT;
1634         blkdev_put(bdev, FMODE_READ);
1635         return ret;
1636 }
1637
1638 int btrfs_find_device_missing_or_by_path(struct btrfs_root *root,
1639                                          char *device_path,
1640                                          struct btrfs_device **device)
1641 {
1642         *device = NULL;
1643         if (strcmp(device_path, "missing") == 0) {
1644                 struct list_head *devices;
1645                 struct btrfs_device *tmp;
1646
1647                 devices = &root->fs_info->fs_devices->devices;
1648                 /*
1649                  * It is safe to read the devices since the volume_mutex
1650                  * is held by the caller.
1651                  */
1652                 list_for_each_entry(tmp, devices, dev_list) {
1653                         if (tmp->in_fs_metadata && !tmp->bdev) {
1654                                 *device = tmp;
1655                                 break;
1656                         }
1657                 }
1658
1659                 if (!*device) {
1660                         pr_err("btrfs: no missing device found\n");
1661                         return -ENOENT;
1662                 }
1663
1664                 return 0;
1665         } else {
1666                 return btrfs_find_device_by_path(root, device_path, device);
1667         }
1668 }
1669
1670 /*
1671  * does all the dirty work required for changing file system's UUID.
1672  */
1673 static int btrfs_prepare_sprout(struct btrfs_root *root)
1674 {
1675         struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
1676         struct btrfs_fs_devices *old_devices;
1677         struct btrfs_fs_devices *seed_devices;
1678         struct btrfs_super_block *disk_super = root->fs_info->super_copy;
1679         struct btrfs_device *device;
1680         u64 super_flags;
1681
1682         BUG_ON(!mutex_is_locked(&uuid_mutex));
1683         if (!fs_devices->seeding)
1684                 return -EINVAL;
1685
1686         seed_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
1687         if (!seed_devices)
1688                 return -ENOMEM;
1689
1690         old_devices = clone_fs_devices(fs_devices);
1691         if (IS_ERR(old_devices)) {
1692                 kfree(seed_devices);
1693                 return PTR_ERR(old_devices);
1694         }
1695
1696         list_add(&old_devices->list, &fs_uuids);
1697
1698         memcpy(seed_devices, fs_devices, sizeof(*seed_devices));
1699         seed_devices->opened = 1;
1700         INIT_LIST_HEAD(&seed_devices->devices);
1701         INIT_LIST_HEAD(&seed_devices->alloc_list);
1702         mutex_init(&seed_devices->device_list_mutex);
1703
1704         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1705         list_splice_init_rcu(&fs_devices->devices, &seed_devices->devices,
1706                               synchronize_rcu);
1707         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1708
1709         list_splice_init(&fs_devices->alloc_list, &seed_devices->alloc_list);
1710         list_for_each_entry(device, &seed_devices->devices, dev_list) {
1711                 device->fs_devices = seed_devices;
1712         }
1713
1714         fs_devices->seeding = 0;
1715         fs_devices->num_devices = 0;
1716         fs_devices->open_devices = 0;
1717         fs_devices->total_devices = 0;
1718         fs_devices->seed = seed_devices;
1719
1720         generate_random_uuid(fs_devices->fsid);
1721         memcpy(root->fs_info->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1722         memcpy(disk_super->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1723         super_flags = btrfs_super_flags(disk_super) &
1724                       ~BTRFS_SUPER_FLAG_SEEDING;
1725         btrfs_set_super_flags(disk_super, super_flags);
1726
1727         return 0;
1728 }
1729
1730 /*
1731  * strore the expected generation for seed devices in device items.
1732  */
1733 static int btrfs_finish_sprout(struct btrfs_trans_handle *trans,
1734                                struct btrfs_root *root)
1735 {
1736         struct btrfs_path *path;
1737         struct extent_buffer *leaf;
1738         struct btrfs_dev_item *dev_item;
1739         struct btrfs_device *device;
1740         struct btrfs_key key;
1741         u8 fs_uuid[BTRFS_UUID_SIZE];
1742         u8 dev_uuid[BTRFS_UUID_SIZE];
1743         u64 devid;
1744         int ret;
1745
1746         path = btrfs_alloc_path();
1747         if (!path)
1748                 return -ENOMEM;
1749
1750         root = root->fs_info->chunk_root;
1751         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1752         key.offset = 0;
1753         key.type = BTRFS_DEV_ITEM_KEY;
1754
1755         while (1) {
1756                 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
1757                 if (ret < 0)
1758                         goto error;
1759
1760                 leaf = path->nodes[0];
1761 next_slot:
1762                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
1763                         ret = btrfs_next_leaf(root, path);
1764                         if (ret > 0)
1765                                 break;
1766                         if (ret < 0)
1767                                 goto error;
1768                         leaf = path->nodes[0];
1769                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1770                         btrfs_release_path(path);
1771                         continue;
1772                 }
1773
1774                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1775                 if (key.objectid != BTRFS_DEV_ITEMS_OBJECTID ||
1776                     key.type != BTRFS_DEV_ITEM_KEY)
1777                         break;
1778
1779                 dev_item = btrfs_item_ptr(leaf, path->slots[0],
1780                                           struct btrfs_dev_item);
1781                 devid = btrfs_device_id(leaf, dev_item);
1782                 read_extent_buffer(leaf, dev_uuid,
1783                                    (unsigned long)btrfs_device_uuid(dev_item),
1784                                    BTRFS_UUID_SIZE);
1785                 read_extent_buffer(leaf, fs_uuid,
1786                                    (unsigned long)btrfs_device_fsid(dev_item),
1787                                    BTRFS_UUID_SIZE);
1788                 device = btrfs_find_device(root->fs_info, devid, dev_uuid,
1789                                            fs_uuid);
1790                 BUG_ON(!device); /* Logic error */
1791
1792                 if (device->fs_devices->seeding) {
1793                         btrfs_set_device_generation(leaf, dev_item,
1794                                                     device->generation);
1795                         btrfs_mark_buffer_dirty(leaf);
1796                 }
1797
1798                 path->slots[0]++;
1799                 goto next_slot;
1800         }
1801         ret = 0;
1802 error:
1803         btrfs_free_path(path);
1804         return ret;
1805 }
1806
1807 int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
1808 {
1809         struct request_queue *q;
1810         struct btrfs_trans_handle *trans;
1811         struct btrfs_device *device;
1812         struct block_device *bdev;
1813         struct list_head *devices;
1814         struct super_block *sb = root->fs_info->sb;
1815         struct rcu_string *name;
1816         u64 total_bytes;
1817         int seeding_dev = 0;
1818         int ret = 0;
1819
1820         if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
1821                 return -EROFS;
1822
1823         bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
1824                                   root->fs_info->bdev_holder);
1825         if (IS_ERR(bdev))
1826                 return PTR_ERR(bdev);
1827
1828         if (root->fs_info->fs_devices->seeding) {
1829                 seeding_dev = 1;
1830                 down_write(&sb->s_umount);
1831                 mutex_lock(&uuid_mutex);
1832         }
1833
1834         filemap_write_and_wait(bdev->bd_inode->i_mapping);
1835
1836         devices = &root->fs_info->fs_devices->devices;
1837
1838         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1839         list_for_each_entry(device, devices, dev_list) {
1840                 if (device->bdev == bdev) {
1841                         ret = -EEXIST;
1842                         mutex_unlock(
1843                                 &root->fs_info->fs_devices->device_list_mutex);
1844                         goto error;
1845                 }
1846         }
1847         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1848
1849         device = kzalloc(sizeof(*device), GFP_NOFS);
1850         if (!device) {
1851                 /* we can safely leave the fs_devices entry around */
1852                 ret = -ENOMEM;
1853                 goto error;
1854         }
1855
1856         name = rcu_string_strdup(device_path, GFP_NOFS);
1857         if (!name) {
1858                 kfree(device);
1859                 ret = -ENOMEM;
1860                 goto error;
1861         }
1862         rcu_assign_pointer(device->name, name);
1863
1864         ret = find_next_devid(root, &device->devid);
1865         if (ret) {
1866                 rcu_string_free(device->name);
1867                 kfree(device);
1868                 goto error;
1869         }
1870
1871         trans = btrfs_start_transaction(root, 0);
1872         if (IS_ERR(trans)) {
1873                 rcu_string_free(device->name);
1874                 kfree(device);
1875                 ret = PTR_ERR(trans);
1876                 goto error;
1877         }
1878
1879         lock_chunks(root);
1880
1881         q = bdev_get_queue(bdev);
1882         if (blk_queue_discard(q))
1883                 device->can_discard = 1;
1884         device->writeable = 1;
1885         device->work.func = pending_bios_fn;
1886         generate_random_uuid(device->uuid);
1887         spin_lock_init(&device->io_lock);
1888         device->generation = trans->transid;
1889         device->io_width = root->sectorsize;
1890         device->io_align = root->sectorsize;
1891         device->sector_size = root->sectorsize;
1892         device->total_bytes = i_size_read(bdev->bd_inode);
1893         device->disk_total_bytes = device->total_bytes;
1894         device->dev_root = root->fs_info->dev_root;
1895         device->bdev = bdev;
1896         device->in_fs_metadata = 1;
1897         device->is_tgtdev_for_dev_replace = 0;
1898         device->mode = FMODE_EXCL;
1899         set_blocksize(device->bdev, 4096);
1900
1901         if (seeding_dev) {
1902                 sb->s_flags &= ~MS_RDONLY;
1903                 ret = btrfs_prepare_sprout(root);
1904                 BUG_ON(ret); /* -ENOMEM */
1905         }
1906
1907         device->fs_devices = root->fs_info->fs_devices;
1908
1909         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1910         list_add_rcu(&device->dev_list, &root->fs_info->fs_devices->devices);
1911         list_add(&device->dev_alloc_list,
1912                  &root->fs_info->fs_devices->alloc_list);
1913         root->fs_info->fs_devices->num_devices++;
1914         root->fs_info->fs_devices->open_devices++;
1915         root->fs_info->fs_devices->rw_devices++;
1916         root->fs_info->fs_devices->total_devices++;
1917         if (device->can_discard)
1918                 root->fs_info->fs_devices->num_can_discard++;
1919         root->fs_info->fs_devices->total_rw_bytes += device->total_bytes;
1920
1921         spin_lock(&root->fs_info->free_chunk_lock);
1922         root->fs_info->free_chunk_space += device->total_bytes;
1923         spin_unlock(&root->fs_info->free_chunk_lock);
1924
1925         if (!blk_queue_nonrot(bdev_get_queue(bdev)))
1926                 root->fs_info->fs_devices->rotating = 1;
1927
1928         total_bytes = btrfs_super_total_bytes(root->fs_info->super_copy);
1929         btrfs_set_super_total_bytes(root->fs_info->super_copy,
1930                                     total_bytes + device->total_bytes);
1931
1932         total_bytes = btrfs_super_num_devices(root->fs_info->super_copy);
1933         btrfs_set_super_num_devices(root->fs_info->super_copy,
1934                                     total_bytes + 1);
1935         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1936
1937         if (seeding_dev) {
1938                 ret = init_first_rw_device(trans, root, device);
1939                 if (ret) {
1940                         btrfs_abort_transaction(trans, root, ret);
1941                         goto error_trans;
1942                 }
1943                 ret = btrfs_finish_sprout(trans, root);
1944                 if (ret) {
1945                         btrfs_abort_transaction(trans, root, ret);
1946                         goto error_trans;
1947                 }
1948         } else {
1949                 ret = btrfs_add_device(trans, root, device);
1950                 if (ret) {
1951                         btrfs_abort_transaction(trans, root, ret);
1952                         goto error_trans;
1953                 }
1954         }
1955
1956         /*
1957          * we've got more storage, clear any full flags on the space
1958          * infos
1959          */
1960         btrfs_clear_space_info_full(root->fs_info);
1961
1962         unlock_chunks(root);
1963         root->fs_info->num_tolerated_disk_barrier_failures =
1964                 btrfs_calc_num_tolerated_disk_barrier_failures(root->fs_info);
1965         ret = btrfs_commit_transaction(trans, root);
1966
1967         if (seeding_dev) {
1968                 mutex_unlock(&uuid_mutex);
1969                 up_write(&sb->s_umount);
1970
1971                 if (ret) /* transaction commit */
1972                         return ret;
1973
1974                 ret = btrfs_relocate_sys_chunks(root);
1975                 if (ret < 0)
1976                         btrfs_error(root->fs_info, ret,
1977                                     "Failed to relocate sys chunks after "
1978                                     "device initialization. This can be fixed "
1979                                     "using the \"btrfs balance\" command.");
1980                 trans = btrfs_attach_transaction(root);
1981                 if (IS_ERR(trans)) {
1982                         if (PTR_ERR(trans) == -ENOENT)
1983                                 return 0;
1984                         return PTR_ERR(trans);
1985                 }
1986                 ret = btrfs_commit_transaction(trans, root);
1987         }
1988
1989         return ret;
1990
1991 error_trans:
1992         unlock_chunks(root);
1993         btrfs_end_transaction(trans, root);
1994         rcu_string_free(device->name);
1995         kfree(device);
1996 error:
1997         blkdev_put(bdev, FMODE_EXCL);
1998         if (seeding_dev) {
1999                 mutex_unlock(&uuid_mutex);
2000                 up_write(&sb->s_umount);
2001         }
2002         return ret;
2003 }
2004
2005 int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
2006                                   struct btrfs_device **device_out)
2007 {
2008         struct request_queue *q;
2009         struct btrfs_device *device;
2010         struct block_device *bdev;
2011         struct btrfs_fs_info *fs_info = root->fs_info;
2012         struct list_head *devices;
2013         struct rcu_string *name;
2014         int ret = 0;
2015
2016         *device_out = NULL;
2017         if (fs_info->fs_devices->seeding)
2018                 return -EINVAL;
2019
2020         bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
2021                                   fs_info->bdev_holder);
2022         if (IS_ERR(bdev))
2023                 return PTR_ERR(bdev);
2024
2025         filemap_write_and_wait(bdev->bd_inode->i_mapping);
2026
2027         devices = &fs_info->fs_devices->devices;
2028         list_for_each_entry(device, devices, dev_list) {
2029                 if (device->bdev == bdev) {
2030                         ret = -EEXIST;
2031                         goto error;
2032                 }
2033         }
2034
2035         device = kzalloc(sizeof(*device), GFP_NOFS);
2036         if (!device) {
2037                 ret = -ENOMEM;
2038                 goto error;
2039         }
2040
2041         name = rcu_string_strdup(device_path, GFP_NOFS);
2042         if (!name) {
2043                 kfree(device);
2044                 ret = -ENOMEM;
2045                 goto error;
2046         }
2047         rcu_assign_pointer(device->name, name);
2048
2049         q = bdev_get_queue(bdev);
2050         if (blk_queue_discard(q))
2051                 device->can_discard = 1;
2052         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
2053         device->writeable = 1;
2054         device->work.func = pending_bios_fn;
2055         generate_random_uuid(device->uuid);
2056         device->devid = BTRFS_DEV_REPLACE_DEVID;
2057         spin_lock_init(&device->io_lock);
2058         device->generation = 0;
2059         device->io_width = root->sectorsize;
2060         device->io_align = root->sectorsize;
2061         device->sector_size = root->sectorsize;
2062         device->total_bytes = i_size_read(bdev->bd_inode);
2063         device->disk_total_bytes = device->total_bytes;
2064         device->dev_root = fs_info->dev_root;
2065         device->bdev = bdev;
2066         device->in_fs_metadata = 1;
2067         device->is_tgtdev_for_dev_replace = 1;
2068         device->mode = FMODE_EXCL;
2069         set_blocksize(device->bdev, 4096);
2070         device->fs_devices = fs_info->fs_devices;
2071         list_add(&device->dev_list, &fs_info->fs_devices->devices);
2072         fs_info->fs_devices->num_devices++;
2073         fs_info->fs_devices->open_devices++;
2074         if (device->can_discard)
2075                 fs_info->fs_devices->num_can_discard++;
2076         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
2077
2078         *device_out = device;
2079         return ret;
2080
2081 error:
2082         blkdev_put(bdev, FMODE_EXCL);
2083         return ret;
2084 }
2085
2086 void btrfs_init_dev_replace_tgtdev_for_resume(struct btrfs_fs_info *fs_info,
2087                                               struct btrfs_device *tgtdev)
2088 {
2089         WARN_ON(fs_info->fs_devices->rw_devices == 0);
2090         tgtdev->io_width = fs_info->dev_root->sectorsize;
2091         tgtdev->io_align = fs_info->dev_root->sectorsize;
2092         tgtdev->sector_size = fs_info->dev_root->sectorsize;
2093         tgtdev->dev_root = fs_info->dev_root;
2094         tgtdev->in_fs_metadata = 1;
2095 }
2096
2097 static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
2098                                         struct btrfs_device *device)
2099 {
2100         int ret;
2101         struct btrfs_path *path;
2102         struct btrfs_root *root;
2103         struct btrfs_dev_item *dev_item;
2104         struct extent_buffer *leaf;
2105         struct btrfs_key key;
2106
2107         root = device->dev_root->fs_info->chunk_root;
2108
2109         path = btrfs_alloc_path();
2110         if (!path)
2111                 return -ENOMEM;
2112
2113         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
2114         key.type = BTRFS_DEV_ITEM_KEY;
2115         key.offset = device->devid;
2116
2117         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
2118         if (ret < 0)
2119                 goto out;
2120
2121         if (ret > 0) {
2122                 ret = -ENOENT;
2123                 goto out;
2124         }
2125
2126         leaf = path->nodes[0];
2127         dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
2128
2129         btrfs_set_device_id(leaf, dev_item, device->devid);
2130         btrfs_set_device_type(leaf, dev_item, device->type);
2131         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
2132         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
2133         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
2134         btrfs_set_device_total_bytes(leaf, dev_item, device->disk_total_bytes);
2135         btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
2136         btrfs_mark_buffer_dirty(leaf);
2137
2138 out:
2139         btrfs_free_path(path);
2140         return ret;
2141 }
2142
2143 static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
2144                       struct btrfs_device *device, u64 new_size)
2145 {
2146         struct btrfs_super_block *super_copy =
2147                 device->dev_root->fs_info->super_copy;
2148         u64 old_total = btrfs_super_total_bytes(super_copy);
2149         u64 diff = new_size - device->total_bytes;
2150
2151         if (!device->writeable)
2152                 return -EACCES;
2153         if (new_size <= device->total_bytes ||
2154             device->is_tgtdev_for_dev_replace)
2155                 return -EINVAL;
2156
2157         btrfs_set_super_total_bytes(super_copy, old_total + diff);
2158         device->fs_devices->total_rw_bytes += diff;
2159
2160         device->total_bytes = new_size;
2161         device->disk_total_bytes = new_size;
2162         btrfs_clear_space_info_full(device->dev_root->fs_info);
2163
2164         return btrfs_update_device(trans, device);
2165 }
2166
2167 int btrfs_grow_device(struct btrfs_trans_handle *trans,
2168                       struct btrfs_device *device, u64 new_size)
2169 {
2170         int ret;
2171         lock_chunks(device->dev_root);
2172         ret = __btrfs_grow_device(trans, device, new_size);
2173         unlock_chunks(device->dev_root);
2174         return ret;
2175 }
2176
2177 static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
2178                             struct btrfs_root *root,
2179                             u64 chunk_tree, u64 chunk_objectid,
2180                             u64 chunk_offset)
2181 {
2182         int ret;
2183         struct btrfs_path *path;
2184         struct btrfs_key key;
2185
2186         root = root->fs_info->chunk_root;
2187         path = btrfs_alloc_path();
2188         if (!path)
2189                 return -ENOMEM;
2190
2191         key.objectid = chunk_objectid;
2192         key.offset = chunk_offset;
2193         key.type = BTRFS_CHUNK_ITEM_KEY;
2194
2195         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
2196         if (ret < 0)
2197                 goto out;
2198         else if (ret > 0) { /* Logic error or corruption */
2199                 btrfs_error(root->fs_info, -ENOENT,
2200                             "Failed lookup while freeing chunk.");
2201                 ret = -ENOENT;
2202                 goto out;
2203         }
2204
2205         ret = btrfs_del_item(trans, root, path);
2206         if (ret < 0)
2207                 btrfs_error(root->fs_info, ret,
2208                             "Failed to delete chunk item.");
2209 out:
2210         btrfs_free_path(path);
2211         return ret;
2212 }
2213
2214 static int btrfs_del_sys_chunk(struct btrfs_root *root, u64 chunk_objectid, u64
2215                         chunk_offset)
2216 {
2217         struct btrfs_super_block *super_copy = root->fs_info->super_copy;
2218         struct btrfs_disk_key *disk_key;
2219         struct btrfs_chunk *chunk;
2220         u8 *ptr;
2221         int ret = 0;
2222         u32 num_stripes;
2223         u32 array_size;
2224         u32 len = 0;
2225         u32 cur;
2226         struct btrfs_key key;
2227
2228         array_size = btrfs_super_sys_array_size(super_copy);
2229
2230         ptr = super_copy->sys_chunk_array;
2231         cur = 0;
2232
2233         while (cur < array_size) {
2234                 disk_key = (struct btrfs_disk_key *)ptr;
2235                 btrfs_disk_key_to_cpu(&key, disk_key);
2236
2237                 len = sizeof(*disk_key);
2238
2239                 if (key.type == BTRFS_CHUNK_ITEM_KEY) {
2240                         chunk = (struct btrfs_chunk *)(ptr + len);
2241                         num_stripes = btrfs_stack_chunk_num_stripes(chunk);
2242                         len += btrfs_chunk_item_size(num_stripes);
2243                 } else {
2244                         ret = -EIO;
2245                         break;
2246                 }
2247                 if (key.objectid == chunk_objectid &&
2248                     key.offset == chunk_offset) {
2249                         memmove(ptr, ptr + len, array_size - (cur + len));
2250                         array_size -= len;
2251                         btrfs_set_super_sys_array_size(super_copy, array_size);
2252                 } else {
2253                         ptr += len;
2254                         cur += len;
2255                 }
2256         }
2257         return ret;
2258 }
2259
2260 static int btrfs_relocate_chunk(struct btrfs_root *root,
2261                          u64 chunk_tree, u64 chunk_objectid,
2262                          u64 chunk_offset)
2263 {
2264         struct extent_map_tree *em_tree;
2265         struct btrfs_root *extent_root;
2266         struct btrfs_trans_handle *trans;
2267         struct extent_map *em;
2268         struct map_lookup *map;
2269         int ret;
2270         int i;
2271
2272         root = root->fs_info->chunk_root;
2273         extent_root = root->fs_info->extent_root;
2274         em_tree = &root->fs_info->mapping_tree.map_tree;
2275
2276         ret = btrfs_can_relocate(extent_root, chunk_offset);
2277         if (ret)
2278                 return -ENOSPC;
2279
2280         /* step one, relocate all the extents inside this chunk */
2281         ret = btrfs_relocate_block_group(extent_root, chunk_offset);
2282         if (ret)
2283                 return ret;
2284
2285         trans = btrfs_start_transaction(root, 0);
2286         BUG_ON(IS_ERR(trans));
2287
2288         lock_chunks(root);
2289
2290         /*
2291          * step two, delete the device extents and the
2292          * chunk tree entries
2293          */
2294         read_lock(&em_tree->lock);
2295         em = lookup_extent_mapping(em_tree, chunk_offset, 1);
2296         read_unlock(&em_tree->lock);
2297
2298         BUG_ON(!em || em->start > chunk_offset ||
2299                em->start + em->len < chunk_offset);
2300         map = (struct map_lookup *)em->bdev;
2301
2302         for (i = 0; i < map->num_stripes; i++) {
2303                 ret = btrfs_free_dev_extent(trans, map->stripes[i].dev,
2304                                             map->stripes[i].physical);
2305                 BUG_ON(ret);
2306
2307                 if (map->stripes[i].dev) {
2308                         ret = btrfs_update_device(trans, map->stripes[i].dev);
2309                         BUG_ON(ret);
2310                 }
2311         }
2312         ret = btrfs_free_chunk(trans, root, chunk_tree, chunk_objectid,
2313                                chunk_offset);
2314
2315         BUG_ON(ret);
2316
2317         trace_btrfs_chunk_free(root, map, chunk_offset, em->len);
2318
2319         if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
2320                 ret = btrfs_del_sys_chunk(root, chunk_objectid, chunk_offset);
2321                 BUG_ON(ret);
2322         }
2323
2324         ret = btrfs_remove_block_group(trans, extent_root, chunk_offset);
2325         BUG_ON(ret);
2326
2327         write_lock(&em_tree->lock);
2328         remove_extent_mapping(em_tree, em);
2329         write_unlock(&em_tree->lock);
2330
2331         kfree(map);
2332         em->bdev = NULL;
2333
2334         /* once for the tree */
2335         free_extent_map(em);
2336         /* once for us */
2337         free_extent_map(em);
2338
2339         unlock_chunks(root);
2340         btrfs_end_transaction(trans, root);
2341         return 0;
2342 }
2343
2344 static int btrfs_relocate_sys_chunks(struct btrfs_root *root)
2345 {
2346         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
2347         struct btrfs_path *path;
2348         struct extent_buffer *leaf;
2349         struct btrfs_chunk *chunk;
2350         struct btrfs_key key;
2351         struct btrfs_key found_key;
2352         u64 chunk_tree = chunk_root->root_key.objectid;
2353         u64 chunk_type;
2354         bool retried = false;
2355         int failed = 0;
2356         int ret;
2357
2358         path = btrfs_alloc_path();
2359         if (!path)
2360                 return -ENOMEM;
2361
2362 again:
2363         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
2364         key.offset = (u64)-1;
2365         key.type = BTRFS_CHUNK_ITEM_KEY;
2366
2367         while (1) {
2368                 ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
2369                 if (ret < 0)
2370                         goto error;
2371                 BUG_ON(ret == 0); /* Corruption */
2372
2373                 ret = btrfs_previous_item(chunk_root, path, key.objectid,
2374                                           key.type);
2375                 if (ret < 0)
2376                         goto error;
2377                 if (ret > 0)
2378                         break;
2379
2380                 leaf = path->nodes[0];
2381                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2382
2383                 chunk = btrfs_item_ptr(leaf, path->slots[0],
2384                                        struct btrfs_chunk);
2385                 chunk_type = btrfs_chunk_type(leaf, chunk);
2386                 btrfs_release_path(path);
2387
2388                 if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM) {
2389                         ret = btrfs_relocate_chunk(chunk_root, chunk_tree,
2390                                                    found_key.objectid,
2391                                                    found_key.offset);
2392                         if (ret == -ENOSPC)
2393                                 failed++;
2394                         else if (ret)
2395                                 BUG();
2396                 }
2397
2398                 if (found_key.offset == 0)
2399                         break;
2400                 key.offset = found_key.offset - 1;
2401         }
2402         ret = 0;
2403         if (failed && !retried) {
2404                 failed = 0;
2405                 retried = true;
2406                 goto again;
2407         } else if (failed && retried) {
2408                 WARN_ON(1);
2409                 ret = -ENOSPC;
2410         }
2411 error:
2412         btrfs_free_path(path);
2413         return ret;
2414 }
2415
2416 static int insert_balance_item(struct btrfs_root *root,
2417                                struct btrfs_balance_control *bctl)
2418 {
2419         struct btrfs_trans_handle *trans;
2420         struct btrfs_balance_item *item;
2421         struct btrfs_disk_balance_args disk_bargs;
2422         struct btrfs_path *path;
2423         struct extent_buffer *leaf;
2424         struct btrfs_key key;
2425         int ret, err;
2426
2427         path = btrfs_alloc_path();
2428         if (!path)
2429                 return -ENOMEM;
2430
2431         trans = btrfs_start_transaction(root, 0);
2432         if (IS_ERR(trans)) {
2433                 btrfs_free_path(path);
2434                 return PTR_ERR(trans);
2435         }
2436
2437         key.objectid = BTRFS_BALANCE_OBJECTID;
2438         key.type = BTRFS_BALANCE_ITEM_KEY;
2439         key.offset = 0;
2440
2441         ret = btrfs_insert_empty_item(trans, root, path, &key,
2442                                       sizeof(*item));
2443         if (ret)
2444                 goto out;
2445
2446         leaf = path->nodes[0];
2447         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_balance_item);
2448
2449         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
2450
2451         btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->data);
2452         btrfs_set_balance_data(leaf, item, &disk_bargs);
2453         btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->meta);
2454         btrfs_set_balance_meta(leaf, item, &disk_bargs);
2455         btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->sys);
2456         btrfs_set_balance_sys(leaf, item, &disk_bargs);
2457
2458         btrfs_set_balance_flags(leaf, item, bctl->flags);
2459
2460         btrfs_mark_buffer_dirty(leaf);
2461 out:
2462         btrfs_free_path(path);
2463         err = btrfs_commit_transaction(trans, root);
2464         if (err && !ret)
2465                 ret = err;
2466         return ret;
2467 }
2468
2469 static int del_balance_item(struct btrfs_root *root)
2470 {
2471         struct btrfs_trans_handle *trans;
2472         struct btrfs_path *path;
2473         struct btrfs_key key;
2474         int ret, err;
2475
2476         path = btrfs_alloc_path();
2477         if (!path)
2478                 return -ENOMEM;
2479
2480         trans = btrfs_start_transaction(root, 0);
2481         if (IS_ERR(trans)) {
2482                 btrfs_free_path(path);
2483                 return PTR_ERR(trans);
2484         }
2485
2486         key.objectid = BTRFS_BALANCE_OBJECTID;
2487         key.type = BTRFS_BALANCE_ITEM_KEY;
2488         key.offset = 0;
2489
2490         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
2491         if (ret < 0)
2492                 goto out;
2493         if (ret > 0) {
2494                 ret = -ENOENT;
2495                 goto out;
2496         }
2497
2498         ret = btrfs_del_item(trans, root, path);
2499 out:
2500         btrfs_free_path(path);
2501         err = btrfs_commit_transaction(trans, root);
2502         if (err && !ret)
2503                 ret = err;
2504         return ret;
2505 }
2506
2507 /*
2508  * This is a heuristic used to reduce the number of chunks balanced on
2509  * resume after balance was interrupted.
2510  */
2511 static void update_balance_args(struct btrfs_balance_control *bctl)
2512 {
2513         /*
2514          * Turn on soft mode for chunk types that were being converted.
2515          */
2516         if (bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT)
2517                 bctl->data.flags |= BTRFS_BALANCE_ARGS_SOFT;
2518         if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT)
2519                 bctl->sys.flags |= BTRFS_BALANCE_ARGS_SOFT;
2520         if (bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT)
2521                 bctl->meta.flags |= BTRFS_BALANCE_ARGS_SOFT;
2522
2523         /*
2524          * Turn on usage filter if is not already used.  The idea is
2525          * that chunks that we have already balanced should be
2526          * reasonably full.  Don't do it for chunks that are being
2527          * converted - that will keep us from relocating unconverted
2528          * (albeit full) chunks.
2529          */
2530         if (!(bctl->data.flags & BTRFS_BALANCE_ARGS_USAGE) &&
2531             !(bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
2532                 bctl->data.flags |= BTRFS_BALANCE_ARGS_USAGE;
2533                 bctl->data.usage = 90;
2534         }
2535         if (!(bctl->sys.flags & BTRFS_BALANCE_ARGS_USAGE) &&
2536             !(bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
2537                 bctl->sys.flags |= BTRFS_BALANCE_ARGS_USAGE;
2538                 bctl->sys.usage = 90;
2539         }
2540         if (!(bctl->meta.flags & BTRFS_BALANCE_ARGS_USAGE) &&
2541             !(bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
2542                 bctl->meta.flags |= BTRFS_BALANCE_ARGS_USAGE;
2543                 bctl->meta.usage = 90;
2544         }
2545 }
2546
2547 /*
2548  * Should be called with both balance and volume mutexes held to
2549  * serialize other volume operations (add_dev/rm_dev/resize) with
2550  * restriper.  Same goes for unset_balance_control.
2551  */
2552 static void set_balance_control(struct btrfs_balance_control *bctl)
2553 {
2554         struct btrfs_fs_info *fs_info = bctl->fs_info;
2555
2556         BUG_ON(fs_info->balance_ctl);
2557
2558         spin_lock(&fs_info->balance_lock);
2559         fs_info->balance_ctl = bctl;
2560         spin_unlock(&fs_info->balance_lock);
2561 }
2562
2563 static void unset_balance_control(struct btrfs_fs_info *fs_info)
2564 {
2565         struct btrfs_balance_control *bctl = fs_info->balance_ctl;
2566
2567         BUG_ON(!fs_info->balance_ctl);
2568
2569         spin_lock(&fs_info->balance_lock);
2570         fs_info->balance_ctl = NULL;
2571         spin_unlock(&fs_info->balance_lock);
2572
2573         kfree(bctl);
2574 }
2575
2576 /*
2577  * Balance filters.  Return 1 if chunk should be filtered out
2578  * (should not be balanced).
2579  */
2580 static int chunk_profiles_filter(u64 chunk_type,
2581                                  struct btrfs_balance_args *bargs)
2582 {
2583         chunk_type = chunk_to_extended(chunk_type) &
2584                                 BTRFS_EXTENDED_PROFILE_MASK;
2585
2586         if (bargs->profiles & chunk_type)
2587                 return 0;
2588
2589         return 1;
2590 }
2591
2592 static int chunk_usage_filter(struct btrfs_fs_info *fs_info, u64 chunk_offset,
2593                               struct btrfs_balance_args *bargs)
2594 {
2595         struct btrfs_block_group_cache *cache;
2596         u64 chunk_used, user_thresh;
2597         int ret = 1;
2598
2599         cache = btrfs_lookup_block_group(fs_info, chunk_offset);
2600         chunk_used = btrfs_block_group_used(&cache->item);
2601
2602         user_thresh = div_factor_fine(cache->key.offset, bargs->usage);
2603         if (chunk_used < user_thresh)
2604                 ret = 0;
2605
2606         btrfs_put_block_group(cache);
2607         return ret;
2608 }
2609
2610 static int chunk_devid_filter(struct extent_buffer *leaf,
2611                               struct btrfs_chunk *chunk,
2612                               struct btrfs_balance_args *bargs)
2613 {
2614         struct btrfs_stripe *stripe;
2615         int num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
2616         int i;
2617
2618         for (i = 0; i < num_stripes; i++) {
2619                 stripe = btrfs_stripe_nr(chunk, i);
2620                 if (btrfs_stripe_devid(leaf, stripe) == bargs->devid)
2621                         return 0;
2622         }
2623
2624         return 1;
2625 }
2626
2627 /* [pstart, pend) */
2628 static int chunk_drange_filter(struct extent_buffer *leaf,
2629                                struct btrfs_chunk *chunk,
2630                                u64 chunk_offset,
2631                                struct btrfs_balance_args *bargs)
2632 {
2633         struct btrfs_stripe *stripe;
2634         int num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
2635         u64 stripe_offset;
2636         u64 stripe_length;
2637         int factor;
2638         int i;
2639
2640         if (!(bargs->flags & BTRFS_BALANCE_ARGS_DEVID))
2641                 return 0;
2642
2643         if (btrfs_chunk_type(leaf, chunk) & (BTRFS_BLOCK_GROUP_DUP |
2644              BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10))
2645                 factor = 2;
2646         else
2647                 factor = 1;
2648         factor = num_stripes / factor;
2649
2650         for (i = 0; i < num_stripes; i++) {
2651                 stripe = btrfs_stripe_nr(chunk, i);
2652                 if (btrfs_stripe_devid(leaf, stripe) != bargs->devid)
2653                         continue;
2654
2655                 stripe_offset = btrfs_stripe_offset(leaf, stripe);
2656                 stripe_length = btrfs_chunk_length(leaf, chunk);
2657                 do_div(stripe_length, factor);
2658
2659                 if (stripe_offset < bargs->pend &&
2660                     stripe_offset + stripe_length > bargs->pstart)
2661                         return 0;
2662         }
2663
2664         return 1;
2665 }
2666
2667 /* [vstart, vend) */
2668 static int chunk_vrange_filter(struct extent_buffer *leaf,
2669                                struct btrfs_chunk *chunk,
2670                                u64 chunk_offset,
2671                                struct btrfs_balance_args *bargs)
2672 {
2673         if (chunk_offset < bargs->vend &&
2674             chunk_offset + btrfs_chunk_length(leaf, chunk) > bargs->vstart)
2675                 /* at least part of the chunk is inside this vrange */
2676                 return 0;
2677
2678         return 1;
2679 }
2680
2681 static int chunk_soft_convert_filter(u64 chunk_type,
2682                                      struct btrfs_balance_args *bargs)
2683 {
2684         if (!(bargs->flags & BTRFS_BALANCE_ARGS_CONVERT))
2685                 return 0;
2686
2687         chunk_type = chunk_to_extended(chunk_type) &
2688                                 BTRFS_EXTENDED_PROFILE_MASK;
2689
2690         if (bargs->target == chunk_type)
2691                 return 1;
2692
2693         return 0;
2694 }
2695
2696 static int should_balance_chunk(struct btrfs_root *root,
2697                                 struct extent_buffer *leaf,
2698                                 struct btrfs_chunk *chunk, u64 chunk_offset)
2699 {
2700         struct btrfs_balance_control *bctl = root->fs_info->balance_ctl;
2701         struct btrfs_balance_args *bargs = NULL;
2702         u64 chunk_type = btrfs_chunk_type(leaf, chunk);
2703
2704         /* type filter */
2705         if (!((chunk_type & BTRFS_BLOCK_GROUP_TYPE_MASK) &
2706               (bctl->flags & BTRFS_BALANCE_TYPE_MASK))) {
2707                 return 0;
2708         }
2709
2710         if (chunk_type & BTRFS_BLOCK_GROUP_DATA)
2711                 bargs = &bctl->data;
2712         else if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM)
2713                 bargs = &bctl->sys;
2714         else if (chunk_type & BTRFS_BLOCK_GROUP_METADATA)
2715                 bargs = &bctl->meta;
2716
2717         /* profiles filter */
2718         if ((bargs->flags & BTRFS_BALANCE_ARGS_PROFILES) &&
2719             chunk_profiles_filter(chunk_type, bargs)) {
2720                 return 0;
2721         }
2722
2723         /* usage filter */
2724         if ((bargs->flags & BTRFS_BALANCE_ARGS_USAGE) &&
2725             chunk_usage_filter(bctl->fs_info, chunk_offset, bargs)) {
2726                 return 0;
2727         }
2728
2729         /* devid filter */
2730         if ((bargs->flags & BTRFS_BALANCE_ARGS_DEVID) &&
2731             chunk_devid_filter(leaf, chunk, bargs)) {
2732                 return 0;
2733         }
2734
2735         /* drange filter, makes sense only with devid filter */
2736         if ((bargs->flags & BTRFS_BALANCE_ARGS_DRANGE) &&
2737             chunk_drange_filter(leaf, chunk, chunk_offset, bargs)) {
2738                 return 0;
2739         }
2740
2741         /* vrange filter */
2742         if ((bargs->flags & BTRFS_BALANCE_ARGS_VRANGE) &&
2743             chunk_vrange_filter(leaf, chunk, chunk_offset, bargs)) {
2744                 return 0;
2745         }
2746
2747         /* soft profile changing mode */
2748         if ((bargs->flags & BTRFS_BALANCE_ARGS_SOFT) &&
2749             chunk_soft_convert_filter(chunk_type, bargs)) {
2750                 return 0;
2751         }
2752
2753         return 1;
2754 }
2755
2756 static int __btrfs_balance(struct btrfs_fs_info *fs_info)
2757 {
2758         struct btrfs_balance_control *bctl = fs_info->balance_ctl;
2759         struct btrfs_root *chunk_root = fs_info->chunk_root;
2760         struct btrfs_root *dev_root = fs_info->dev_root;
2761         struct list_head *devices;
2762         struct btrfs_device *device;
2763         u64 old_size;
2764         u64 size_to_free;
2765         struct btrfs_chunk *chunk;
2766         struct btrfs_path *path;
2767         struct btrfs_key key;
2768         struct btrfs_key found_key;
2769         struct btrfs_trans_handle *trans;
2770         struct extent_buffer *leaf;
2771         int slot;
2772         int ret;
2773         int enospc_errors = 0;
2774         bool counting = true;
2775
2776         /* step one make some room on all the devices */
2777         devices = &fs_info->fs_devices->devices;
2778         list_for_each_entry(device, devices, dev_list) {
2779                 old_size = device->total_bytes;
2780                 size_to_free = div_factor(old_size, 1);
2781                 size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
2782                 if (!device->writeable ||
2783                     device->total_bytes - device->bytes_used > size_to_free ||
2784                     device->is_tgtdev_for_dev_replace)
2785                         continue;
2786
2787                 ret = btrfs_shrink_device(device, old_size - size_to_free);
2788                 if (ret == -ENOSPC)
2789                         break;
2790                 BUG_ON(ret);
2791
2792                 trans = btrfs_start_transaction(dev_root, 0);
2793                 BUG_ON(IS_ERR(trans));
2794
2795                 ret = btrfs_grow_device(trans, device, old_size);
2796                 BUG_ON(ret);
2797
2798                 btrfs_end_transaction(trans, dev_root);
2799         }
2800
2801         /* step two, relocate all the chunks */
2802         path = btrfs_alloc_path();
2803         if (!path) {
2804                 ret = -ENOMEM;
2805                 goto error;
2806         }
2807
2808         /* zero out stat counters */
2809         spin_lock(&fs_info->balance_lock);
2810         memset(&bctl->stat, 0, sizeof(bctl->stat));
2811         spin_unlock(&fs_info->balance_lock);
2812 again:
2813         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
2814         key.offset = (u64)-1;
2815         key.type = BTRFS_CHUNK_ITEM_KEY;
2816
2817         while (1) {
2818                 if ((!counting && atomic_read(&fs_info->balance_pause_req)) ||
2819                     atomic_read(&fs_info->balance_cancel_req)) {
2820                         ret = -ECANCELED;
2821                         goto error;
2822                 }
2823
2824                 ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
2825                 if (ret < 0)
2826                         goto error;
2827
2828                 /*
2829                  * this shouldn't happen, it means the last relocate
2830                  * failed
2831                  */
2832                 if (ret == 0)
2833                         BUG(); /* FIXME break ? */
2834
2835                 ret = btrfs_previous_item(chunk_root, path, 0,
2836                                           BTRFS_CHUNK_ITEM_KEY);
2837                 if (ret) {
2838                         ret = 0;
2839                         break;
2840                 }
2841
2842                 leaf = path->nodes[0];
2843                 slot = path->slots[0];
2844                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
2845
2846                 if (found_key.objectid != key.objectid)
2847                         break;
2848
2849                 /* chunk zero is special */
2850                 if (found_key.offset == 0)
2851                         break;
2852
2853                 chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
2854
2855                 if (!counting) {
2856                         spin_lock(&fs_info->balance_lock);
2857                         bctl->stat.considered++;
2858                         spin_unlock(&fs_info->balance_lock);
2859                 }
2860
2861                 ret = should_balance_chunk(chunk_root, leaf, chunk,
2862                                            found_key.offset);
2863                 btrfs_release_path(path);
2864                 if (!ret)
2865                         goto loop;
2866
2867                 if (counting) {
2868                         spin_lock(&fs_info->balance_lock);
2869                         bctl->stat.expected++;
2870                         spin_unlock(&fs_info->balance_lock);
2871                         goto loop;
2872                 }
2873
2874                 ret = btrfs_relocate_chunk(chunk_root,
2875                                            chunk_root->root_key.objectid,
2876                                            found_key.objectid,
2877                                            found_key.offset);
2878                 if (ret && ret != -ENOSPC)
2879                         goto error;
2880                 if (ret == -ENOSPC) {
2881                         enospc_errors++;
2882                 } else {
2883                         spin_lock(&fs_info->balance_lock);
2884                         bctl->stat.completed++;
2885                         spin_unlock(&fs_info->balance_lock);
2886                 }
2887 loop:
2888                 key.offset = found_key.offset - 1;
2889         }
2890
2891         if (counting) {
2892                 btrfs_release_path(path);
2893                 counting = false;
2894                 goto again;
2895         }
2896 error:
2897         btrfs_free_path(path);
2898         if (enospc_errors) {
2899                 printk(KERN_INFO "btrfs: %d enospc errors during balance\n",
2900                        enospc_errors);
2901                 if (!ret)
2902                         ret = -ENOSPC;
2903         }
2904
2905         return ret;
2906 }
2907
2908 /**
2909  * alloc_profile_is_valid - see if a given profile is valid and reduced
2910  * @flags: profile to validate
2911  * @extended: if true @flags is treated as an extended profile
2912  */
2913 static int alloc_profile_is_valid(u64 flags, int extended)
2914 {
2915         u64 mask = (extended ? BTRFS_EXTENDED_PROFILE_MASK :
2916                                BTRFS_BLOCK_GROUP_PROFILE_MASK);
2917
2918         flags &= ~BTRFS_BLOCK_GROUP_TYPE_MASK;
2919
2920         /* 1) check that all other bits are zeroed */
2921         if (flags & ~mask)
2922                 return 0;
2923
2924         /* 2) see if profile is reduced */
2925         if (flags == 0)
2926                 return !extended; /* "0" is valid for usual profiles */
2927
2928         /* true if exactly one bit set */
2929         return (flags & (flags - 1)) == 0;
2930 }
2931
2932 static inline int balance_need_close(struct btrfs_fs_info *fs_info)
2933 {
2934         /* cancel requested || normal exit path */
2935         return atomic_read(&fs_info->balance_cancel_req) ||
2936                 (atomic_read(&fs_info->balance_pause_req) == 0 &&
2937                  atomic_read(&fs_info->balance_cancel_req) == 0);
2938 }
2939
2940 static void __cancel_balance(struct btrfs_fs_info *fs_info)
2941 {
2942         int ret;
2943
2944         unset_balance_control(fs_info);
2945         ret = del_balance_item(fs_info->tree_root);
2946         BUG_ON(ret);
2947 }
2948
2949 void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
2950                                struct btrfs_ioctl_balance_args *bargs);
2951
2952 /*
2953  * Should be called with both balance and volume mutexes held
2954  */
2955 int btrfs_balance(struct btrfs_balance_control *bctl,
2956                   struct btrfs_ioctl_balance_args *bargs)
2957 {
2958         struct btrfs_fs_info *fs_info = bctl->fs_info;
2959         u64 allowed;
2960         int mixed = 0;
2961         int ret;
2962         u64 num_devices;
2963
2964         if (btrfs_fs_closing(fs_info) ||
2965             atomic_read(&fs_info->balance_pause_req) ||
2966             atomic_read(&fs_info->balance_cancel_req)) {
2967                 ret = -EINVAL;
2968                 goto out;
2969         }
2970
2971         allowed = btrfs_super_incompat_flags(fs_info->super_copy);
2972         if (allowed & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
2973                 mixed = 1;
2974
2975         /*
2976          * In case of mixed groups both data and meta should be picked,
2977          * and identical options should be given for both of them.
2978          */
2979         allowed = BTRFS_BALANCE_DATA | BTRFS_BALANCE_METADATA;
2980         if (mixed && (bctl->flags & allowed)) {
2981                 if (!(bctl->flags & BTRFS_BALANCE_DATA) ||
2982                     !(bctl->flags & BTRFS_BALANCE_METADATA) ||
2983                     memcmp(&bctl->data, &bctl->meta, sizeof(bctl->data))) {
2984                         printk(KERN_ERR "btrfs: with mixed groups data and "
2985                                "metadata balance options must be the same\n");
2986                         ret = -EINVAL;
2987                         goto out;
2988                 }
2989         }
2990
2991         num_devices = fs_info->fs_devices->num_devices;
2992         btrfs_dev_replace_lock(&fs_info->dev_replace);
2993         if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
2994                 BUG_ON(num_devices < 1);
2995                 num_devices--;
2996         }
2997         btrfs_dev_replace_unlock(&fs_info->dev_replace);
2998         allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
2999         if (num_devices == 1)
3000                 allowed |= BTRFS_BLOCK_GROUP_DUP;
3001         else if (num_devices < 4)
3002                 allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);
3003         else
3004                 allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
3005                                 BTRFS_BLOCK_GROUP_RAID10);
3006
3007         if ((bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
3008             (!alloc_profile_is_valid(bctl->data.target, 1) ||
3009              (bctl->data.target & ~allowed))) {
3010                 printk(KERN_ERR "btrfs: unable to start balance with target "
3011                        "data profile %llu\n",
3012                        (unsigned long long)bctl->data.target);
3013                 ret = -EINVAL;
3014                 goto out;
3015         }
3016         if ((bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
3017             (!alloc_profile_is_valid(bctl->meta.target, 1) ||
3018              (bctl->meta.target & ~allowed))) {
3019                 printk(KERN_ERR "btrfs: unable to start balance with target "
3020                        "metadata profile %llu\n",
3021                        (unsigned long long)bctl->meta.target);
3022                 ret = -EINVAL;
3023                 goto out;
3024         }
3025         if ((bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
3026             (!alloc_profile_is_valid(bctl->sys.target, 1) ||
3027              (bctl->sys.target & ~allowed))) {
3028                 printk(KERN_ERR "btrfs: unable to start balance with target "
3029                        "system profile %llu\n",
3030                        (unsigned long long)bctl->sys.target);
3031                 ret = -EINVAL;
3032                 goto out;
3033         }
3034
3035         /* allow dup'ed data chunks only in mixed mode */
3036         if (!mixed && (bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
3037             (bctl->data.target & BTRFS_BLOCK_GROUP_DUP)) {
3038                 printk(KERN_ERR "btrfs: dup for data is not allowed\n");
3039                 ret = -EINVAL;
3040                 goto out;
3041         }
3042
3043         /* allow to reduce meta or sys integrity only if force set */
3044         allowed = BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
3045                         BTRFS_BLOCK_GROUP_RAID10;
3046         if (((bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
3047              (fs_info->avail_system_alloc_bits & allowed) &&
3048              !(bctl->sys.target & allowed)) ||
3049             ((bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
3050              (fs_info->avail_metadata_alloc_bits & allowed) &&
3051              !(bctl->meta.target & allowed))) {
3052                 if (bctl->flags & BTRFS_BALANCE_FORCE) {
3053                         printk(KERN_INFO "btrfs: force reducing metadata "
3054                                "integrity\n");
3055                 } else {
3056                         printk(KERN_ERR "btrfs: balance will reduce metadata "
3057                                "integrity, use force if you want this\n");
3058                         ret = -EINVAL;
3059                         goto out;
3060                 }
3061         }
3062
3063         if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {
3064                 int num_tolerated_disk_barrier_failures;
3065                 u64 target = bctl->sys.target;
3066
3067                 num_tolerated_disk_barrier_failures =
3068                         btrfs_calc_num_tolerated_disk_barrier_failures(fs_info);
3069                 if (num_tolerated_disk_barrier_failures > 0 &&
3070                     (target &
3071                      (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID0 |
3072                       BTRFS_AVAIL_ALLOC_BIT_SINGLE)))
3073                         num_tolerated_disk_barrier_failures = 0;
3074                 else if (num_tolerated_disk_barrier_failures > 1 &&
3075                          (target &
3076                           (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10)))
3077                         num_tolerated_disk_barrier_failures = 1;
3078
3079                 fs_info->num_tolerated_disk_barrier_failures =
3080                         num_tolerated_disk_barrier_failures;
3081         }
3082
3083         ret = insert_balance_item(fs_info->tree_root, bctl);
3084         if (ret && ret != -EEXIST)
3085                 goto out;
3086
3087         if (!(bctl->flags & BTRFS_BALANCE_RESUME)) {
3088                 BUG_ON(ret == -EEXIST);
3089                 set_balance_control(bctl);
3090         } else {
3091                 BUG_ON(ret != -EEXIST);
3092                 spin_lock(&fs_info->balance_lock);
3093                 update_balance_args(bctl);
3094                 spin_unlock(&fs_info->balance_lock);
3095         }
3096
3097         atomic_inc(&fs_info->balance_running);
3098         mutex_unlock(&fs_info->balance_mutex);
3099
3100         ret = __btrfs_balance(fs_info);
3101
3102         mutex_lock(&fs_info->balance_mutex);
3103         atomic_dec(&fs_info->balance_running);
3104
3105         if (bargs) {
3106                 memset(bargs, 0, sizeof(*bargs));
3107                 update_ioctl_balance_args(fs_info, 0, bargs);
3108         }
3109
3110         if ((ret && ret != -ECANCELED && ret != -ENOSPC) ||
3111             balance_need_close(fs_info)) {
3112                 __cancel_balance(fs_info);
3113         }
3114
3115         if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {
3116                 fs_info->num_tolerated_disk_barrier_failures =
3117                         btrfs_calc_num_tolerated_disk_barrier_failures(fs_info);
3118         }
3119
3120         wake_up(&fs_info->balance_wait_q);
3121
3122         return ret;
3123 out:
3124         if (bctl->flags & BTRFS_BALANCE_RESUME)
3125                 __cancel_balance(fs_info);
3126         else
3127                 kfree(bctl);
3128         return ret;
3129 }
3130
3131 static int balance_kthread(void *data)
3132 {
3133         struct btrfs_fs_info *fs_info = data;
3134         int ret = 0;
3135
3136         mutex_lock(&fs_info->volume_mutex);
3137         mutex_lock(&fs_info->balance_mutex);
3138
3139         if (fs_info->balance_ctl) {
3140                 printk(KERN_INFO "btrfs: continuing balance\n");
3141                 ret = btrfs_balance(fs_info->balance_ctl, NULL);
3142         }
3143
3144         atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
3145         mutex_unlock(&fs_info->balance_mutex);
3146         mutex_unlock(&fs_info->volume_mutex);
3147
3148         return ret;
3149 }
3150
3151 int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info)
3152 {
3153         struct task_struct *tsk;
3154
3155         spin_lock(&fs_info->balance_lock);
3156         if (!fs_info->balance_ctl) {
3157                 spin_unlock(&fs_info->balance_lock);
3158                 return 0;
3159         }
3160         spin_unlock(&fs_info->balance_lock);
3161
3162         if (btrfs_test_opt(fs_info->tree_root, SKIP_BALANCE)) {
3163                 printk(KERN_INFO "btrfs: force skipping balance\n");
3164                 return 0;
3165         }
3166
3167         WARN_ON(atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1));
3168         tsk = kthread_run(balance_kthread, fs_info, "btrfs-balance");
3169         if (IS_ERR(tsk))
3170                 return PTR_ERR(tsk);
3171
3172         return 0;
3173 }
3174
3175 int btrfs_recover_balance(struct btrfs_fs_info *fs_info)
3176 {
3177         struct btrfs_balance_control *bctl;
3178         struct btrfs_balance_item *item;
3179         struct btrfs_disk_balance_args disk_bargs;
3180         struct btrfs_path *path;
3181         struct extent_buffer *leaf;
3182         struct btrfs_key key;
3183         int ret;
3184
3185         path = btrfs_alloc_path();
3186         if (!path)
3187                 return -ENOMEM;
3188
3189         key.objectid = BTRFS_BALANCE_OBJECTID;
3190         key.type = BTRFS_BALANCE_ITEM_KEY;
3191         key.offset = 0;
3192
3193         ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
3194         if (ret < 0)
3195                 goto out;
3196         if (ret > 0) { /* ret = -ENOENT; */
3197                 ret = 0;
3198                 goto out;
3199         }
3200
3201         bctl = kzalloc(sizeof(*bctl), GFP_NOFS);
3202         if (!bctl) {
3203                 ret = -ENOMEM;
3204                 goto out;
3205         }
3206
3207         leaf = path->nodes[0];
3208         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_balance_item);
3209
3210         bctl->fs_info = fs_info;
3211         bctl->flags = btrfs_balance_flags(leaf, item);
3212         bctl->flags |= BTRFS_BALANCE_RESUME;
3213
3214         btrfs_balance_data(leaf, item, &disk_bargs);
3215         btrfs_disk_balance_args_to_cpu(&bctl->data, &disk_bargs);
3216         btrfs_balance_meta(leaf, item, &disk_bargs);
3217         btrfs_disk_balance_args_to_cpu(&bctl->meta, &disk_bargs);
3218         btrfs_balance_sys(leaf, item, &disk_bargs);
3219         btrfs_disk_balance_args_to_cpu(&bctl->sys, &disk_bargs);
3220
3221         mutex_lock(&fs_info->volume_mutex);
3222         mutex_lock(&fs_info->balance_mutex);
3223
3224         set_balance_control(bctl);
3225
3226         mutex_unlock(&fs_info->balance_mutex);
3227         mutex_unlock(&fs_info->volume_mutex);
3228 out:
3229         btrfs_free_path(path);
3230         return ret;
3231 }
3232
3233 int btrfs_pause_balance(struct btrfs_fs_info *fs_info)
3234 {
3235         int ret = 0;
3236
3237         mutex_lock(&fs_info->balance_mutex);
3238         if (!fs_info->balance_ctl) {
3239                 mutex_unlock(&fs_info->balance_mutex);
3240                 return -ENOTCONN;
3241         }
3242
3243         if (atomic_read(&fs_info->balance_running)) {
3244                 atomic_inc(&fs_info->balance_pause_req);
3245                 mutex_unlock(&fs_info->balance_mutex);
3246
3247                 wait_event(fs_info->balance_wait_q,
3248                            atomic_read(&fs_info->balance_running) == 0);
3249
3250                 mutex_lock(&fs_info->balance_mutex);
3251                 /* we are good with balance_ctl ripped off from under us */
3252                 BUG_ON(atomic_read(&fs_info->balance_running));
3253                 atomic_dec(&fs_info->balance_pause_req);
3254         } else {
3255                 ret = -ENOTCONN;
3256         }
3257
3258         mutex_unlock(&fs_info->balance_mutex);
3259         return ret;
3260 }
3261
3262 int btrfs_cancel_balance(struct btrfs_fs_info *fs_info)
3263 {
3264         mutex_lock(&fs_info->balance_mutex);
3265         if (!fs_info->balance_ctl) {
3266                 mutex_unlock(&fs_info->balance_mutex);
3267                 return -ENOTCONN;
3268         }
3269
3270         atomic_inc(&fs_info->balance_cancel_req);
3271         /*
3272          * if we are running just wait and return, balance item is
3273          * deleted in btrfs_balance in this case
3274          */
3275         if (atomic_read(&fs_info->balance_running)) {
3276                 mutex_unlock(&fs_info->balance_mutex);
3277                 wait_event(fs_info->balance_wait_q,
3278                            atomic_read(&fs_info->balance_running) == 0);
3279                 mutex_lock(&fs_info->balance_mutex);
3280         } else {
3281                 /* __cancel_balance needs volume_mutex */
3282                 mutex_unlock(&fs_info->balance_mutex);
3283                 mutex_lock(&fs_info->volume_mutex);
3284                 mutex_lock(&fs_info->balance_mutex);
3285
3286                 if (fs_info->balance_ctl)
3287                         __cancel_balance(fs_info);
3288
3289                 mutex_unlock(&fs_info->volume_mutex);
3290         }
3291
3292         BUG_ON(fs_info->balance_ctl || atomic_read(&fs_info->balance_running));
3293         atomic_dec(&fs_info->balance_cancel_req);
3294         mutex_unlock(&fs_info->balance_mutex);
3295         return 0;
3296 }
3297
3298 /*
3299  * shrinking a device means finding all of the device extents past
3300  * the new size, and then following the back refs to the chunks.
3301  * The chunk relocation code actually frees the device extent
3302  */
3303 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
3304 {
3305         struct btrfs_trans_handle *trans;
3306         struct btrfs_root *root = device->dev_root;
3307         struct btrfs_dev_extent *dev_extent = NULL;
3308         struct btrfs_path *path;
3309         u64 length;
3310         u64 chunk_tree;
3311         u64 chunk_objectid;
3312         u64 chunk_offset;
3313         int ret;
3314         int slot;
3315         int failed = 0;
3316         bool retried = false;
3317         struct extent_buffer *l;
3318         struct btrfs_key key;
3319         struct btrfs_super_block *super_copy = root->fs_info->super_copy;
3320         u64 old_total = btrfs_super_total_bytes(super_copy);
3321         u64 old_size = device->total_bytes;
3322         u64 diff = device->total_bytes - new_size;
3323
3324         if (device->is_tgtdev_for_dev_replace)
3325                 return -EINVAL;
3326
3327         path = btrfs_alloc_path();
3328         if (!path)
3329                 return -ENOMEM;
3330
3331         path->reada = 2;
3332
3333         lock_chunks(root);
3334
3335         device->total_bytes = new_size;
3336         if (device->writeable) {
3337                 device->fs_devices->total_rw_bytes -= diff;
3338                 spin_lock(&root->fs_info->free_chunk_lock);
3339                 root->fs_info->free_chunk_space -= diff;
3340                 spin_unlock(&root->fs_info->free_chunk_lock);
3341         }
3342         unlock_chunks(root);
3343
3344 again:
3345         key.objectid = device->devid;
3346         key.offset = (u64)-1;
3347         key.type = BTRFS_DEV_EXTENT_KEY;
3348
3349         do {
3350                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3351                 if (ret < 0)
3352                         goto done;
3353
3354                 ret = btrfs_previous_item(root, path, 0, key.type);
3355                 if (ret < 0)
3356                         goto done;
3357                 if (ret) {
3358                         ret = 0;
3359                         btrfs_release_path(path);
3360                         break;
3361                 }
3362
3363                 l = path->nodes[0];
3364                 slot = path->slots[0];
3365