Btrfs: find smallest available device extent during chunk allocation
[linux-2.6.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/buffer_head.h>
21 #include <linux/blkdev.h>
22 #include <linux/random.h>
23 #include <linux/iocontext.h>
24 #include <asm/div64.h>
25 #include "compat.h"
26 #include "ctree.h"
27 #include "extent_map.h"
28 #include "disk-io.h"
29 #include "transaction.h"
30 #include "print-tree.h"
31 #include "volumes.h"
32 #include "async-thread.h"
33
34 struct map_lookup {
35         u64 type;
36         int io_align;
37         int io_width;
38         int stripe_len;
39         int sector_size;
40         int num_stripes;
41         int sub_stripes;
42         struct btrfs_bio_stripe stripes[];
43 };
44
45 static int init_first_rw_device(struct btrfs_trans_handle *trans,
46                                 struct btrfs_root *root,
47                                 struct btrfs_device *device);
48 static int btrfs_relocate_sys_chunks(struct btrfs_root *root);
49
50 #define map_lookup_size(n) (sizeof(struct map_lookup) + \
51                             (sizeof(struct btrfs_bio_stripe) * (n)))
52
53 static DEFINE_MUTEX(uuid_mutex);
54 static LIST_HEAD(fs_uuids);
55
56 void btrfs_lock_volumes(void)
57 {
58         mutex_lock(&uuid_mutex);
59 }
60
61 void btrfs_unlock_volumes(void)
62 {
63         mutex_unlock(&uuid_mutex);
64 }
65
66 static void lock_chunks(struct btrfs_root *root)
67 {
68         mutex_lock(&root->fs_info->chunk_mutex);
69 }
70
71 static void unlock_chunks(struct btrfs_root *root)
72 {
73         mutex_unlock(&root->fs_info->chunk_mutex);
74 }
75
76 static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
77 {
78         struct btrfs_device *device;
79         WARN_ON(fs_devices->opened);
80         while (!list_empty(&fs_devices->devices)) {
81                 device = list_entry(fs_devices->devices.next,
82                                     struct btrfs_device, dev_list);
83                 list_del(&device->dev_list);
84                 kfree(device->name);
85                 kfree(device);
86         }
87         kfree(fs_devices);
88 }
89
90 int btrfs_cleanup_fs_uuids(void)
91 {
92         struct btrfs_fs_devices *fs_devices;
93
94         while (!list_empty(&fs_uuids)) {
95                 fs_devices = list_entry(fs_uuids.next,
96                                         struct btrfs_fs_devices, list);
97                 list_del(&fs_devices->list);
98                 free_fs_devices(fs_devices);
99         }
100         return 0;
101 }
102
103 static noinline struct btrfs_device *__find_device(struct list_head *head,
104                                                    u64 devid, u8 *uuid)
105 {
106         struct btrfs_device *dev;
107
108         list_for_each_entry(dev, head, dev_list) {
109                 if (dev->devid == devid &&
110                     (!uuid || !memcmp(dev->uuid, uuid, BTRFS_UUID_SIZE))) {
111                         return dev;
112                 }
113         }
114         return NULL;
115 }
116
117 static noinline struct btrfs_fs_devices *find_fsid(u8 *fsid)
118 {
119         struct btrfs_fs_devices *fs_devices;
120
121         list_for_each_entry(fs_devices, &fs_uuids, list) {
122                 if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
123                         return fs_devices;
124         }
125         return NULL;
126 }
127
128 static void requeue_list(struct btrfs_pending_bios *pending_bios,
129                         struct bio *head, struct bio *tail)
130 {
131
132         struct bio *old_head;
133
134         old_head = pending_bios->head;
135         pending_bios->head = head;
136         if (pending_bios->tail)
137                 tail->bi_next = old_head;
138         else
139                 pending_bios->tail = tail;
140 }
141
142 /*
143  * we try to collect pending bios for a device so we don't get a large
144  * number of procs sending bios down to the same device.  This greatly
145  * improves the schedulers ability to collect and merge the bios.
146  *
147  * But, it also turns into a long list of bios to process and that is sure
148  * to eventually make the worker thread block.  The solution here is to
149  * make some progress and then put this work struct back at the end of
150  * the list if the block device is congested.  This way, multiple devices
151  * can make progress from a single worker thread.
152  */
153 static noinline int run_scheduled_bios(struct btrfs_device *device)
154 {
155         struct bio *pending;
156         struct backing_dev_info *bdi;
157         struct btrfs_fs_info *fs_info;
158         struct btrfs_pending_bios *pending_bios;
159         struct bio *tail;
160         struct bio *cur;
161         int again = 0;
162         unsigned long num_run;
163         unsigned long num_sync_run;
164         unsigned long batch_run = 0;
165         unsigned long limit;
166         unsigned long last_waited = 0;
167         int force_reg = 0;
168
169         bdi = blk_get_backing_dev_info(device->bdev);
170         fs_info = device->dev_root->fs_info;
171         limit = btrfs_async_submit_limit(fs_info);
172         limit = limit * 2 / 3;
173
174         /* we want to make sure that every time we switch from the sync
175          * list to the normal list, we unplug
176          */
177         num_sync_run = 0;
178
179 loop:
180         spin_lock(&device->io_lock);
181
182 loop_lock:
183         num_run = 0;
184
185         /* take all the bios off the list at once and process them
186          * later on (without the lock held).  But, remember the
187          * tail and other pointers so the bios can be properly reinserted
188          * into the list if we hit congestion
189          */
190         if (!force_reg && device->pending_sync_bios.head) {
191                 pending_bios = &device->pending_sync_bios;
192                 force_reg = 1;
193         } else {
194                 pending_bios = &device->pending_bios;
195                 force_reg = 0;
196         }
197
198         pending = pending_bios->head;
199         tail = pending_bios->tail;
200         WARN_ON(pending && !tail);
201
202         /*
203          * if pending was null this time around, no bios need processing
204          * at all and we can stop.  Otherwise it'll loop back up again
205          * and do an additional check so no bios are missed.
206          *
207          * device->running_pending is used to synchronize with the
208          * schedule_bio code.
209          */
210         if (device->pending_sync_bios.head == NULL &&
211             device->pending_bios.head == NULL) {
212                 again = 0;
213                 device->running_pending = 0;
214         } else {
215                 again = 1;
216                 device->running_pending = 1;
217         }
218
219         pending_bios->head = NULL;
220         pending_bios->tail = NULL;
221
222         spin_unlock(&device->io_lock);
223
224         /*
225          * if we're doing the regular priority list, make sure we unplug
226          * for any high prio bios we've sent down
227          */
228         if (pending_bios == &device->pending_bios && num_sync_run > 0) {
229                 num_sync_run = 0;
230                 blk_run_backing_dev(bdi, NULL);
231         }
232
233         while (pending) {
234
235                 rmb();
236                 /* we want to work on both lists, but do more bios on the
237                  * sync list than the regular list
238                  */
239                 if ((num_run > 32 &&
240                     pending_bios != &device->pending_sync_bios &&
241                     device->pending_sync_bios.head) ||
242                    (num_run > 64 && pending_bios == &device->pending_sync_bios &&
243                     device->pending_bios.head)) {
244                         spin_lock(&device->io_lock);
245                         requeue_list(pending_bios, pending, tail);
246                         goto loop_lock;
247                 }
248
249                 cur = pending;
250                 pending = pending->bi_next;
251                 cur->bi_next = NULL;
252                 atomic_dec(&fs_info->nr_async_bios);
253
254                 if (atomic_read(&fs_info->nr_async_bios) < limit &&
255                     waitqueue_active(&fs_info->async_submit_wait))
256                         wake_up(&fs_info->async_submit_wait);
257
258                 BUG_ON(atomic_read(&cur->bi_cnt) == 0);
259                 submit_bio(cur->bi_rw, cur);
260                 num_run++;
261                 batch_run++;
262
263                 if (bio_sync(cur))
264                         num_sync_run++;
265
266                 if (need_resched()) {
267                         if (num_sync_run) {
268                                 blk_run_backing_dev(bdi, NULL);
269                                 num_sync_run = 0;
270                         }
271                         cond_resched();
272                 }
273
274                 /*
275                  * we made progress, there is more work to do and the bdi
276                  * is now congested.  Back off and let other work structs
277                  * run instead
278                  */
279                 if (pending && bdi_write_congested(bdi) && batch_run > 32 &&
280                     fs_info->fs_devices->open_devices > 1) {
281                         struct io_context *ioc;
282
283                         ioc = current->io_context;
284
285                         /*
286                          * the main goal here is that we don't want to
287                          * block if we're going to be able to submit
288                          * more requests without blocking.
289                          *
290                          * This code does two great things, it pokes into
291                          * the elevator code from a filesystem _and_
292                          * it makes assumptions about how batching works.
293                          */
294                         if (ioc && ioc->nr_batch_requests > 0 &&
295                             time_before(jiffies, ioc->last_waited + HZ/50UL) &&
296                             (last_waited == 0 ||
297                              ioc->last_waited == last_waited)) {
298                                 /*
299                                  * we want to go through our batch of
300                                  * requests and stop.  So, we copy out
301                                  * the ioc->last_waited time and test
302                                  * against it before looping
303                                  */
304                                 last_waited = ioc->last_waited;
305                                 if (need_resched()) {
306                                         if (num_sync_run) {
307                                                 blk_run_backing_dev(bdi, NULL);
308                                                 num_sync_run = 0;
309                                         }
310                                         cond_resched();
311                                 }
312                                 continue;
313                         }
314                         spin_lock(&device->io_lock);
315                         requeue_list(pending_bios, pending, tail);
316                         device->running_pending = 1;
317
318                         spin_unlock(&device->io_lock);
319                         btrfs_requeue_work(&device->work);
320                         goto done;
321                 }
322         }
323
324         if (num_sync_run) {
325                 num_sync_run = 0;
326                 blk_run_backing_dev(bdi, NULL);
327         }
328
329         cond_resched();
330         if (again)
331                 goto loop;
332
333         spin_lock(&device->io_lock);
334         if (device->pending_bios.head || device->pending_sync_bios.head)
335                 goto loop_lock;
336         spin_unlock(&device->io_lock);
337
338         /*
339          * IO has already been through a long path to get here.  Checksumming,
340          * async helper threads, perhaps compression.  We've done a pretty
341          * good job of collecting a batch of IO and should just unplug
342          * the device right away.
343          *
344          * This will help anyone who is waiting on the IO, they might have
345          * already unplugged, but managed to do so before the bio they
346          * cared about found its way down here.
347          */
348         blk_run_backing_dev(bdi, NULL);
349 done:
350         return 0;
351 }
352
353 static void pending_bios_fn(struct btrfs_work *work)
354 {
355         struct btrfs_device *device;
356
357         device = container_of(work, struct btrfs_device, work);
358         run_scheduled_bios(device);
359 }
360
361 static noinline int device_list_add(const char *path,
362                            struct btrfs_super_block *disk_super,
363                            u64 devid, struct btrfs_fs_devices **fs_devices_ret)
364 {
365         struct btrfs_device *device;
366         struct btrfs_fs_devices *fs_devices;
367         u64 found_transid = btrfs_super_generation(disk_super);
368
369         fs_devices = find_fsid(disk_super->fsid);
370         if (!fs_devices) {
371                 fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
372                 if (!fs_devices)
373                         return -ENOMEM;
374                 INIT_LIST_HEAD(&fs_devices->devices);
375                 INIT_LIST_HEAD(&fs_devices->alloc_list);
376                 list_add(&fs_devices->list, &fs_uuids);
377                 memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
378                 fs_devices->latest_devid = devid;
379                 fs_devices->latest_trans = found_transid;
380                 mutex_init(&fs_devices->device_list_mutex);
381                 device = NULL;
382         } else {
383                 device = __find_device(&fs_devices->devices, devid,
384                                        disk_super->dev_item.uuid);
385         }
386         if (!device) {
387                 if (fs_devices->opened)
388                         return -EBUSY;
389
390                 device = kzalloc(sizeof(*device), GFP_NOFS);
391                 if (!device) {
392                         /* we can safely leave the fs_devices entry around */
393                         return -ENOMEM;
394                 }
395                 device->devid = devid;
396                 device->work.func = pending_bios_fn;
397                 memcpy(device->uuid, disk_super->dev_item.uuid,
398                        BTRFS_UUID_SIZE);
399                 device->barriers = 1;
400                 spin_lock_init(&device->io_lock);
401                 device->name = kstrdup(path, GFP_NOFS);
402                 if (!device->name) {
403                         kfree(device);
404                         return -ENOMEM;
405                 }
406                 INIT_LIST_HEAD(&device->dev_alloc_list);
407
408                 mutex_lock(&fs_devices->device_list_mutex);
409                 list_add(&device->dev_list, &fs_devices->devices);
410                 mutex_unlock(&fs_devices->device_list_mutex);
411
412                 device->fs_devices = fs_devices;
413                 fs_devices->num_devices++;
414         }
415
416         if (found_transid > fs_devices->latest_trans) {
417                 fs_devices->latest_devid = devid;
418                 fs_devices->latest_trans = found_transid;
419         }
420         *fs_devices_ret = fs_devices;
421         return 0;
422 }
423
424 static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
425 {
426         struct btrfs_fs_devices *fs_devices;
427         struct btrfs_device *device;
428         struct btrfs_device *orig_dev;
429
430         fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
431         if (!fs_devices)
432                 return ERR_PTR(-ENOMEM);
433
434         INIT_LIST_HEAD(&fs_devices->devices);
435         INIT_LIST_HEAD(&fs_devices->alloc_list);
436         INIT_LIST_HEAD(&fs_devices->list);
437         mutex_init(&fs_devices->device_list_mutex);
438         fs_devices->latest_devid = orig->latest_devid;
439         fs_devices->latest_trans = orig->latest_trans;
440         memcpy(fs_devices->fsid, orig->fsid, sizeof(fs_devices->fsid));
441
442         mutex_lock(&orig->device_list_mutex);
443         list_for_each_entry(orig_dev, &orig->devices, dev_list) {
444                 device = kzalloc(sizeof(*device), GFP_NOFS);
445                 if (!device)
446                         goto error;
447
448                 device->name = kstrdup(orig_dev->name, GFP_NOFS);
449                 if (!device->name)
450                         goto error;
451
452                 device->devid = orig_dev->devid;
453                 device->work.func = pending_bios_fn;
454                 memcpy(device->uuid, orig_dev->uuid, sizeof(device->uuid));
455                 device->barriers = 1;
456                 spin_lock_init(&device->io_lock);
457                 INIT_LIST_HEAD(&device->dev_list);
458                 INIT_LIST_HEAD(&device->dev_alloc_list);
459
460                 list_add(&device->dev_list, &fs_devices->devices);
461                 device->fs_devices = fs_devices;
462                 fs_devices->num_devices++;
463         }
464         mutex_unlock(&orig->device_list_mutex);
465         return fs_devices;
466 error:
467         mutex_unlock(&orig->device_list_mutex);
468         free_fs_devices(fs_devices);
469         return ERR_PTR(-ENOMEM);
470 }
471
472 int btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices)
473 {
474         struct btrfs_device *device, *next;
475
476         mutex_lock(&uuid_mutex);
477 again:
478         mutex_lock(&fs_devices->device_list_mutex);
479         list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
480                 if (device->in_fs_metadata)
481                         continue;
482
483                 if (device->bdev) {
484                         close_bdev_exclusive(device->bdev, device->mode);
485                         device->bdev = NULL;
486                         fs_devices->open_devices--;
487                 }
488                 if (device->writeable) {
489                         list_del_init(&device->dev_alloc_list);
490                         device->writeable = 0;
491                         fs_devices->rw_devices--;
492                 }
493                 list_del_init(&device->dev_list);
494                 fs_devices->num_devices--;
495                 kfree(device->name);
496                 kfree(device);
497         }
498         mutex_unlock(&fs_devices->device_list_mutex);
499
500         if (fs_devices->seed) {
501                 fs_devices = fs_devices->seed;
502                 goto again;
503         }
504
505         mutex_unlock(&uuid_mutex);
506         return 0;
507 }
508
509 static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
510 {
511         struct btrfs_device *device;
512
513         if (--fs_devices->opened > 0)
514                 return 0;
515
516         list_for_each_entry(device, &fs_devices->devices, dev_list) {
517                 if (device->bdev) {
518                         close_bdev_exclusive(device->bdev, device->mode);
519                         fs_devices->open_devices--;
520                 }
521                 if (device->writeable) {
522                         list_del_init(&device->dev_alloc_list);
523                         fs_devices->rw_devices--;
524                 }
525
526                 device->bdev = NULL;
527                 device->writeable = 0;
528                 device->in_fs_metadata = 0;
529         }
530         WARN_ON(fs_devices->open_devices);
531         WARN_ON(fs_devices->rw_devices);
532         fs_devices->opened = 0;
533         fs_devices->seeding = 0;
534
535         return 0;
536 }
537
538 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
539 {
540         struct btrfs_fs_devices *seed_devices = NULL;
541         int ret;
542
543         mutex_lock(&uuid_mutex);
544         ret = __btrfs_close_devices(fs_devices);
545         if (!fs_devices->opened) {
546                 seed_devices = fs_devices->seed;
547                 fs_devices->seed = NULL;
548         }
549         mutex_unlock(&uuid_mutex);
550
551         while (seed_devices) {
552                 fs_devices = seed_devices;
553                 seed_devices = fs_devices->seed;
554                 __btrfs_close_devices(fs_devices);
555                 free_fs_devices(fs_devices);
556         }
557         return ret;
558 }
559
560 static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
561                                 fmode_t flags, void *holder)
562 {
563         struct block_device *bdev;
564         struct list_head *head = &fs_devices->devices;
565         struct btrfs_device *device;
566         struct block_device *latest_bdev = NULL;
567         struct buffer_head *bh;
568         struct btrfs_super_block *disk_super;
569         u64 latest_devid = 0;
570         u64 latest_transid = 0;
571         u64 devid;
572         int seeding = 1;
573         int ret = 0;
574
575         list_for_each_entry(device, head, dev_list) {
576                 if (device->bdev)
577                         continue;
578                 if (!device->name)
579                         continue;
580
581                 bdev = open_bdev_exclusive(device->name, flags, holder);
582                 if (IS_ERR(bdev)) {
583                         printk(KERN_INFO "open %s failed\n", device->name);
584                         goto error;
585                 }
586                 set_blocksize(bdev, 4096);
587
588                 bh = btrfs_read_dev_super(bdev);
589                 if (!bh)
590                         goto error_close;
591
592                 disk_super = (struct btrfs_super_block *)bh->b_data;
593                 devid = le64_to_cpu(disk_super->dev_item.devid);
594                 if (devid != device->devid)
595                         goto error_brelse;
596
597                 if (memcmp(device->uuid, disk_super->dev_item.uuid,
598                            BTRFS_UUID_SIZE))
599                         goto error_brelse;
600
601                 device->generation = btrfs_super_generation(disk_super);
602                 if (!latest_transid || device->generation > latest_transid) {
603                         latest_devid = devid;
604                         latest_transid = device->generation;
605                         latest_bdev = bdev;
606                 }
607
608                 if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING) {
609                         device->writeable = 0;
610                 } else {
611                         device->writeable = !bdev_read_only(bdev);
612                         seeding = 0;
613                 }
614
615                 device->bdev = bdev;
616                 device->in_fs_metadata = 0;
617                 device->mode = flags;
618
619                 if (!blk_queue_nonrot(bdev_get_queue(bdev)))
620                         fs_devices->rotating = 1;
621
622                 fs_devices->open_devices++;
623                 if (device->writeable) {
624                         fs_devices->rw_devices++;
625                         list_add(&device->dev_alloc_list,
626                                  &fs_devices->alloc_list);
627                 }
628                 continue;
629
630 error_brelse:
631                 brelse(bh);
632 error_close:
633                 close_bdev_exclusive(bdev, FMODE_READ);
634 error:
635                 continue;
636         }
637         if (fs_devices->open_devices == 0) {
638                 ret = -EIO;
639                 goto out;
640         }
641         fs_devices->seeding = seeding;
642         fs_devices->opened = 1;
643         fs_devices->latest_bdev = latest_bdev;
644         fs_devices->latest_devid = latest_devid;
645         fs_devices->latest_trans = latest_transid;
646         fs_devices->total_rw_bytes = 0;
647 out:
648         return ret;
649 }
650
651 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
652                        fmode_t flags, void *holder)
653 {
654         int ret;
655
656         mutex_lock(&uuid_mutex);
657         if (fs_devices->opened) {
658                 fs_devices->opened++;
659                 ret = 0;
660         } else {
661                 ret = __btrfs_open_devices(fs_devices, flags, holder);
662         }
663         mutex_unlock(&uuid_mutex);
664         return ret;
665 }
666
667 int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
668                           struct btrfs_fs_devices **fs_devices_ret)
669 {
670         struct btrfs_super_block *disk_super;
671         struct block_device *bdev;
672         struct buffer_head *bh;
673         int ret;
674         u64 devid;
675         u64 transid;
676
677         mutex_lock(&uuid_mutex);
678
679         bdev = open_bdev_exclusive(path, flags, holder);
680
681         if (IS_ERR(bdev)) {
682                 ret = PTR_ERR(bdev);
683                 goto error;
684         }
685
686         ret = set_blocksize(bdev, 4096);
687         if (ret)
688                 goto error_close;
689         bh = btrfs_read_dev_super(bdev);
690         if (!bh) {
691                 ret = -EIO;
692                 goto error_close;
693         }
694         disk_super = (struct btrfs_super_block *)bh->b_data;
695         devid = le64_to_cpu(disk_super->dev_item.devid);
696         transid = btrfs_super_generation(disk_super);
697         if (disk_super->label[0])
698                 printk(KERN_INFO "device label %s ", disk_super->label);
699         else {
700                 /* FIXME, make a readl uuid parser */
701                 printk(KERN_INFO "device fsid %llx-%llx ",
702                        *(unsigned long long *)disk_super->fsid,
703                        *(unsigned long long *)(disk_super->fsid + 8));
704         }
705         printk(KERN_CONT "devid %llu transid %llu %s\n",
706                (unsigned long long)devid, (unsigned long long)transid, path);
707         ret = device_list_add(path, disk_super, devid, fs_devices_ret);
708
709         brelse(bh);
710 error_close:
711         close_bdev_exclusive(bdev, flags);
712 error:
713         mutex_unlock(&uuid_mutex);
714         return ret;
715 }
716
717 /*
718  * this uses a pretty simple search, the expectation is that it is
719  * called very infrequently and that a given device has a small number
720  * of extents
721  */
722 static noinline int find_free_dev_extent(struct btrfs_trans_handle *trans,
723                                          struct btrfs_device *device,
724                                          u64 num_bytes, u64 *start,
725                                          u64 *max_avail)
726 {
727         struct btrfs_key key;
728         struct btrfs_root *root = device->dev_root;
729         struct btrfs_dev_extent *dev_extent = NULL;
730         struct btrfs_path *path;
731         u64 hole_size = 0;
732         u64 last_byte = 0;
733         u64 search_start = 0;
734         u64 search_end = device->total_bytes;
735         int ret;
736         int slot = 0;
737         int start_found;
738         struct extent_buffer *l;
739
740         path = btrfs_alloc_path();
741         if (!path)
742                 return -ENOMEM;
743         path->reada = 2;
744         start_found = 0;
745
746         /* FIXME use last free of some kind */
747
748         /* we don't want to overwrite the superblock on the drive,
749          * so we make sure to start at an offset of at least 1MB
750          */
751         search_start = max((u64)1024 * 1024, search_start);
752
753         if (root->fs_info->alloc_start + num_bytes <= device->total_bytes)
754                 search_start = max(root->fs_info->alloc_start, search_start);
755
756         key.objectid = device->devid;
757         key.offset = search_start;
758         key.type = BTRFS_DEV_EXTENT_KEY;
759         ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
760         if (ret < 0)
761                 goto error;
762         if (ret > 0) {
763                 ret = btrfs_previous_item(root, path, key.objectid, key.type);
764                 if (ret < 0)
765                         goto error;
766                 if (ret > 0)
767                         start_found = 1;
768         }
769         l = path->nodes[0];
770         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
771         while (1) {
772                 l = path->nodes[0];
773                 slot = path->slots[0];
774                 if (slot >= btrfs_header_nritems(l)) {
775                         ret = btrfs_next_leaf(root, path);
776                         if (ret == 0)
777                                 continue;
778                         if (ret < 0)
779                                 goto error;
780 no_more_items:
781                         if (!start_found) {
782                                 if (search_start >= search_end) {
783                                         ret = -ENOSPC;
784                                         goto error;
785                                 }
786                                 *start = search_start;
787                                 start_found = 1;
788                                 goto check_pending;
789                         }
790                         *start = last_byte > search_start ?
791                                 last_byte : search_start;
792                         if (search_end <= *start) {
793                                 ret = -ENOSPC;
794                                 goto error;
795                         }
796                         goto check_pending;
797                 }
798                 btrfs_item_key_to_cpu(l, &key, slot);
799
800                 if (key.objectid < device->devid)
801                         goto next;
802
803                 if (key.objectid > device->devid)
804                         goto no_more_items;
805
806                 if (key.offset >= search_start && key.offset > last_byte &&
807                     start_found) {
808                         if (last_byte < search_start)
809                                 last_byte = search_start;
810                         hole_size = key.offset - last_byte;
811
812                         if (hole_size > *max_avail)
813                                 *max_avail = hole_size;
814
815                         if (key.offset > last_byte &&
816                             hole_size >= num_bytes) {
817                                 *start = last_byte;
818                                 goto check_pending;
819                         }
820                 }
821                 if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
822                         goto next;
823
824                 start_found = 1;
825                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
826                 last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent);
827 next:
828                 path->slots[0]++;
829                 cond_resched();
830         }
831 check_pending:
832         /* we have to make sure we didn't find an extent that has already
833          * been allocated by the map tree or the original allocation
834          */
835         BUG_ON(*start < search_start);
836
837         if (*start + num_bytes > search_end) {
838                 ret = -ENOSPC;
839                 goto error;
840         }
841         /* check for pending inserts here */
842         ret = 0;
843
844 error:
845         btrfs_free_path(path);
846         return ret;
847 }
848
849 static int btrfs_free_dev_extent(struct btrfs_trans_handle *trans,
850                           struct btrfs_device *device,
851                           u64 start)
852 {
853         int ret;
854         struct btrfs_path *path;
855         struct btrfs_root *root = device->dev_root;
856         struct btrfs_key key;
857         struct btrfs_key found_key;
858         struct extent_buffer *leaf = NULL;
859         struct btrfs_dev_extent *extent = NULL;
860
861         path = btrfs_alloc_path();
862         if (!path)
863                 return -ENOMEM;
864
865         key.objectid = device->devid;
866         key.offset = start;
867         key.type = BTRFS_DEV_EXTENT_KEY;
868
869         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
870         if (ret > 0) {
871                 ret = btrfs_previous_item(root, path, key.objectid,
872                                           BTRFS_DEV_EXTENT_KEY);
873                 BUG_ON(ret);
874                 leaf = path->nodes[0];
875                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
876                 extent = btrfs_item_ptr(leaf, path->slots[0],
877                                         struct btrfs_dev_extent);
878                 BUG_ON(found_key.offset > start || found_key.offset +
879                        btrfs_dev_extent_length(leaf, extent) < start);
880                 ret = 0;
881         } else if (ret == 0) {
882                 leaf = path->nodes[0];
883                 extent = btrfs_item_ptr(leaf, path->slots[0],
884                                         struct btrfs_dev_extent);
885         }
886         BUG_ON(ret);
887
888         if (device->bytes_used > 0)
889                 device->bytes_used -= btrfs_dev_extent_length(leaf, extent);
890         ret = btrfs_del_item(trans, root, path);
891         BUG_ON(ret);
892
893         btrfs_free_path(path);
894         return ret;
895 }
896
897 int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
898                            struct btrfs_device *device,
899                            u64 chunk_tree, u64 chunk_objectid,
900                            u64 chunk_offset, u64 start, u64 num_bytes)
901 {
902         int ret;
903         struct btrfs_path *path;
904         struct btrfs_root *root = device->dev_root;
905         struct btrfs_dev_extent *extent;
906         struct extent_buffer *leaf;
907         struct btrfs_key key;
908
909         WARN_ON(!device->in_fs_metadata);
910         path = btrfs_alloc_path();
911         if (!path)
912                 return -ENOMEM;
913
914         key.objectid = device->devid;
915         key.offset = start;
916         key.type = BTRFS_DEV_EXTENT_KEY;
917         ret = btrfs_insert_empty_item(trans, root, path, &key,
918                                       sizeof(*extent));
919         BUG_ON(ret);
920
921         leaf = path->nodes[0];
922         extent = btrfs_item_ptr(leaf, path->slots[0],
923                                 struct btrfs_dev_extent);
924         btrfs_set_dev_extent_chunk_tree(leaf, extent, chunk_tree);
925         btrfs_set_dev_extent_chunk_objectid(leaf, extent, chunk_objectid);
926         btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);
927
928         write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
929                     (unsigned long)btrfs_dev_extent_chunk_tree_uuid(extent),
930                     BTRFS_UUID_SIZE);
931
932         btrfs_set_dev_extent_length(leaf, extent, num_bytes);
933         btrfs_mark_buffer_dirty(leaf);
934         btrfs_free_path(path);
935         return ret;
936 }
937
938 static noinline int find_next_chunk(struct btrfs_root *root,
939                                     u64 objectid, u64 *offset)
940 {
941         struct btrfs_path *path;
942         int ret;
943         struct btrfs_key key;
944         struct btrfs_chunk *chunk;
945         struct btrfs_key found_key;
946
947         path = btrfs_alloc_path();
948         BUG_ON(!path);
949
950         key.objectid = objectid;
951         key.offset = (u64)-1;
952         key.type = BTRFS_CHUNK_ITEM_KEY;
953
954         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
955         if (ret < 0)
956                 goto error;
957
958         BUG_ON(ret == 0);
959
960         ret = btrfs_previous_item(root, path, 0, BTRFS_CHUNK_ITEM_KEY);
961         if (ret) {
962                 *offset = 0;
963         } else {
964                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
965                                       path->slots[0]);
966                 if (found_key.objectid != objectid)
967                         *offset = 0;
968                 else {
969                         chunk = btrfs_item_ptr(path->nodes[0], path->slots[0],
970                                                struct btrfs_chunk);
971                         *offset = found_key.offset +
972                                 btrfs_chunk_length(path->nodes[0], chunk);
973                 }
974         }
975         ret = 0;
976 error:
977         btrfs_free_path(path);
978         return ret;
979 }
980
981 static noinline int find_next_devid(struct btrfs_root *root, u64 *objectid)
982 {
983         int ret;
984         struct btrfs_key key;
985         struct btrfs_key found_key;
986         struct btrfs_path *path;
987
988         root = root->fs_info->chunk_root;
989
990         path = btrfs_alloc_path();
991         if (!path)
992                 return -ENOMEM;
993
994         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
995         key.type = BTRFS_DEV_ITEM_KEY;
996         key.offset = (u64)-1;
997
998         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
999         if (ret < 0)
1000                 goto error;
1001
1002         BUG_ON(ret == 0);
1003
1004         ret = btrfs_previous_item(root, path, BTRFS_DEV_ITEMS_OBJECTID,
1005                                   BTRFS_DEV_ITEM_KEY);
1006         if (ret) {
1007                 *objectid = 1;
1008         } else {
1009                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
1010                                       path->slots[0]);
1011                 *objectid = found_key.offset + 1;
1012         }
1013         ret = 0;
1014 error:
1015         btrfs_free_path(path);
1016         return ret;
1017 }
1018
1019 /*
1020  * the device information is stored in the chunk root
1021  * the btrfs_device struct should be fully filled in
1022  */
1023 int btrfs_add_device(struct btrfs_trans_handle *trans,
1024                      struct btrfs_root *root,
1025                      struct btrfs_device *device)
1026 {
1027         int ret;
1028         struct btrfs_path *path;
1029         struct btrfs_dev_item *dev_item;
1030         struct extent_buffer *leaf;
1031         struct btrfs_key key;
1032         unsigned long ptr;
1033
1034         root = root->fs_info->chunk_root;
1035
1036         path = btrfs_alloc_path();
1037         if (!path)
1038                 return -ENOMEM;
1039
1040         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1041         key.type = BTRFS_DEV_ITEM_KEY;
1042         key.offset = device->devid;
1043
1044         ret = btrfs_insert_empty_item(trans, root, path, &key,
1045                                       sizeof(*dev_item));
1046         if (ret)
1047                 goto out;
1048
1049         leaf = path->nodes[0];
1050         dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
1051
1052         btrfs_set_device_id(leaf, dev_item, device->devid);
1053         btrfs_set_device_generation(leaf, dev_item, 0);
1054         btrfs_set_device_type(leaf, dev_item, device->type);
1055         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
1056         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
1057         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
1058         btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
1059         btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
1060         btrfs_set_device_group(leaf, dev_item, 0);
1061         btrfs_set_device_seek_speed(leaf, dev_item, 0);
1062         btrfs_set_device_bandwidth(leaf, dev_item, 0);
1063         btrfs_set_device_start_offset(leaf, dev_item, 0);
1064
1065         ptr = (unsigned long)btrfs_device_uuid(dev_item);
1066         write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
1067         ptr = (unsigned long)btrfs_device_fsid(dev_item);
1068         write_extent_buffer(leaf, root->fs_info->fsid, ptr, BTRFS_UUID_SIZE);
1069         btrfs_mark_buffer_dirty(leaf);
1070
1071         ret = 0;
1072 out:
1073         btrfs_free_path(path);
1074         return ret;
1075 }
1076
1077 static int btrfs_rm_dev_item(struct btrfs_root *root,
1078                              struct btrfs_device *device)
1079 {
1080         int ret;
1081         struct btrfs_path *path;
1082         struct btrfs_key key;
1083         struct btrfs_trans_handle *trans;
1084
1085         root = root->fs_info->chunk_root;
1086
1087         path = btrfs_alloc_path();
1088         if (!path)
1089                 return -ENOMEM;
1090
1091         trans = btrfs_start_transaction(root, 1);
1092         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1093         key.type = BTRFS_DEV_ITEM_KEY;
1094         key.offset = device->devid;
1095         lock_chunks(root);
1096
1097         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1098         if (ret < 0)
1099                 goto out;
1100
1101         if (ret > 0) {
1102                 ret = -ENOENT;
1103                 goto out;
1104         }
1105
1106         ret = btrfs_del_item(trans, root, path);
1107         if (ret)
1108                 goto out;
1109 out:
1110         btrfs_free_path(path);
1111         unlock_chunks(root);
1112         btrfs_commit_transaction(trans, root);
1113         return ret;
1114 }
1115
1116 int btrfs_rm_device(struct btrfs_root *root, char *device_path)
1117 {
1118         struct btrfs_device *device;
1119         struct btrfs_device *next_device;
1120         struct block_device *bdev;
1121         struct buffer_head *bh = NULL;
1122         struct btrfs_super_block *disk_super;
1123         u64 all_avail;
1124         u64 devid;
1125         u64 num_devices;
1126         u8 *dev_uuid;
1127         int ret = 0;
1128
1129         mutex_lock(&uuid_mutex);
1130         mutex_lock(&root->fs_info->volume_mutex);
1131
1132         all_avail = root->fs_info->avail_data_alloc_bits |
1133                 root->fs_info->avail_system_alloc_bits |
1134                 root->fs_info->avail_metadata_alloc_bits;
1135
1136         if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) &&
1137             root->fs_info->fs_devices->rw_devices <= 4) {
1138                 printk(KERN_ERR "btrfs: unable to go below four devices "
1139                        "on raid10\n");
1140                 ret = -EINVAL;
1141                 goto out;
1142         }
1143
1144         if ((all_avail & BTRFS_BLOCK_GROUP_RAID1) &&
1145             root->fs_info->fs_devices->rw_devices <= 2) {
1146                 printk(KERN_ERR "btrfs: unable to go below two "
1147                        "devices on raid1\n");
1148                 ret = -EINVAL;
1149                 goto out;
1150         }
1151
1152         if (strcmp(device_path, "missing") == 0) {
1153                 struct list_head *devices;
1154                 struct btrfs_device *tmp;
1155
1156                 device = NULL;
1157                 devices = &root->fs_info->fs_devices->devices;
1158                 mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1159                 list_for_each_entry(tmp, devices, dev_list) {
1160                         if (tmp->in_fs_metadata && !tmp->bdev) {
1161                                 device = tmp;
1162                                 break;
1163                         }
1164                 }
1165                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1166                 bdev = NULL;
1167                 bh = NULL;
1168                 disk_super = NULL;
1169                 if (!device) {
1170                         printk(KERN_ERR "btrfs: no missing devices found to "
1171                                "remove\n");
1172                         goto out;
1173                 }
1174         } else {
1175                 bdev = open_bdev_exclusive(device_path, FMODE_READ,
1176                                       root->fs_info->bdev_holder);
1177                 if (IS_ERR(bdev)) {
1178                         ret = PTR_ERR(bdev);
1179                         goto out;
1180                 }
1181
1182                 set_blocksize(bdev, 4096);
1183                 bh = btrfs_read_dev_super(bdev);
1184                 if (!bh) {
1185                         ret = -EIO;
1186                         goto error_close;
1187                 }
1188                 disk_super = (struct btrfs_super_block *)bh->b_data;
1189                 devid = le64_to_cpu(disk_super->dev_item.devid);
1190                 dev_uuid = disk_super->dev_item.uuid;
1191                 device = btrfs_find_device(root, devid, dev_uuid,
1192                                            disk_super->fsid);
1193                 if (!device) {
1194                         ret = -ENOENT;
1195                         goto error_brelse;
1196                 }
1197         }
1198
1199         if (device->writeable && root->fs_info->fs_devices->rw_devices == 1) {
1200                 printk(KERN_ERR "btrfs: unable to remove the only writeable "
1201                        "device\n");
1202                 ret = -EINVAL;
1203                 goto error_brelse;
1204         }
1205
1206         if (device->writeable) {
1207                 list_del_init(&device->dev_alloc_list);
1208                 root->fs_info->fs_devices->rw_devices--;
1209         }
1210
1211         ret = btrfs_shrink_device(device, 0);
1212         if (ret)
1213                 goto error_brelse;
1214
1215         ret = btrfs_rm_dev_item(root->fs_info->chunk_root, device);
1216         if (ret)
1217                 goto error_brelse;
1218
1219         device->in_fs_metadata = 0;
1220
1221         /*
1222          * the device list mutex makes sure that we don't change
1223          * the device list while someone else is writing out all
1224          * the device supers.
1225          */
1226         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1227         list_del_init(&device->dev_list);
1228         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1229
1230         device->fs_devices->num_devices--;
1231
1232         next_device = list_entry(root->fs_info->fs_devices->devices.next,
1233                                  struct btrfs_device, dev_list);
1234         if (device->bdev == root->fs_info->sb->s_bdev)
1235                 root->fs_info->sb->s_bdev = next_device->bdev;
1236         if (device->bdev == root->fs_info->fs_devices->latest_bdev)
1237                 root->fs_info->fs_devices->latest_bdev = next_device->bdev;
1238
1239         if (device->bdev) {
1240                 close_bdev_exclusive(device->bdev, device->mode);
1241                 device->bdev = NULL;
1242                 device->fs_devices->open_devices--;
1243         }
1244
1245         num_devices = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
1246         btrfs_set_super_num_devices(&root->fs_info->super_copy, num_devices);
1247
1248         if (device->fs_devices->open_devices == 0) {
1249                 struct btrfs_fs_devices *fs_devices;
1250                 fs_devices = root->fs_info->fs_devices;
1251                 while (fs_devices) {
1252                         if (fs_devices->seed == device->fs_devices)
1253                                 break;
1254                         fs_devices = fs_devices->seed;
1255                 }
1256                 fs_devices->seed = device->fs_devices->seed;
1257                 device->fs_devices->seed = NULL;
1258                 __btrfs_close_devices(device->fs_devices);
1259                 free_fs_devices(device->fs_devices);
1260         }
1261
1262         /*
1263          * at this point, the device is zero sized.  We want to
1264          * remove it from the devices list and zero out the old super
1265          */
1266         if (device->writeable) {
1267                 /* make sure this device isn't detected as part of
1268                  * the FS anymore
1269                  */
1270                 memset(&disk_super->magic, 0, sizeof(disk_super->magic));
1271                 set_buffer_dirty(bh);
1272                 sync_dirty_buffer(bh);
1273         }
1274
1275         kfree(device->name);
1276         kfree(device);
1277         ret = 0;
1278
1279 error_brelse:
1280         brelse(bh);
1281 error_close:
1282         if (bdev)
1283                 close_bdev_exclusive(bdev, FMODE_READ);
1284 out:
1285         mutex_unlock(&root->fs_info->volume_mutex);
1286         mutex_unlock(&uuid_mutex);
1287         return ret;
1288 }
1289
1290 /*
1291  * does all the dirty work required for changing file system's UUID.
1292  */
1293 static int btrfs_prepare_sprout(struct btrfs_trans_handle *trans,
1294                                 struct btrfs_root *root)
1295 {
1296         struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
1297         struct btrfs_fs_devices *old_devices;
1298         struct btrfs_fs_devices *seed_devices;
1299         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
1300         struct btrfs_device *device;
1301         u64 super_flags;
1302
1303         BUG_ON(!mutex_is_locked(&uuid_mutex));
1304         if (!fs_devices->seeding)
1305                 return -EINVAL;
1306
1307         seed_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
1308         if (!seed_devices)
1309                 return -ENOMEM;
1310
1311         old_devices = clone_fs_devices(fs_devices);
1312         if (IS_ERR(old_devices)) {
1313                 kfree(seed_devices);
1314                 return PTR_ERR(old_devices);
1315         }
1316
1317         list_add(&old_devices->list, &fs_uuids);
1318
1319         memcpy(seed_devices, fs_devices, sizeof(*seed_devices));
1320         seed_devices->opened = 1;
1321         INIT_LIST_HEAD(&seed_devices->devices);
1322         INIT_LIST_HEAD(&seed_devices->alloc_list);
1323         mutex_init(&seed_devices->device_list_mutex);
1324         list_splice_init(&fs_devices->devices, &seed_devices->devices);
1325         list_splice_init(&fs_devices->alloc_list, &seed_devices->alloc_list);
1326         list_for_each_entry(device, &seed_devices->devices, dev_list) {
1327                 device->fs_devices = seed_devices;
1328         }
1329
1330         fs_devices->seeding = 0;
1331         fs_devices->num_devices = 0;
1332         fs_devices->open_devices = 0;
1333         fs_devices->seed = seed_devices;
1334
1335         generate_random_uuid(fs_devices->fsid);
1336         memcpy(root->fs_info->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1337         memcpy(disk_super->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1338         super_flags = btrfs_super_flags(disk_super) &
1339                       ~BTRFS_SUPER_FLAG_SEEDING;
1340         btrfs_set_super_flags(disk_super, super_flags);
1341
1342         return 0;
1343 }
1344
1345 /*
1346  * strore the expected generation for seed devices in device items.
1347  */
1348 static int btrfs_finish_sprout(struct btrfs_trans_handle *trans,
1349                                struct btrfs_root *root)
1350 {
1351         struct btrfs_path *path;
1352         struct extent_buffer *leaf;
1353         struct btrfs_dev_item *dev_item;
1354         struct btrfs_device *device;
1355         struct btrfs_key key;
1356         u8 fs_uuid[BTRFS_UUID_SIZE];
1357         u8 dev_uuid[BTRFS_UUID_SIZE];
1358         u64 devid;
1359         int ret;
1360
1361         path = btrfs_alloc_path();
1362         if (!path)
1363                 return -ENOMEM;
1364
1365         root = root->fs_info->chunk_root;
1366         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1367         key.offset = 0;
1368         key.type = BTRFS_DEV_ITEM_KEY;
1369
1370         while (1) {
1371                 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
1372                 if (ret < 0)
1373                         goto error;
1374
1375                 leaf = path->nodes[0];
1376 next_slot:
1377                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
1378                         ret = btrfs_next_leaf(root, path);
1379                         if (ret > 0)
1380                                 break;
1381                         if (ret < 0)
1382                                 goto error;
1383                         leaf = path->nodes[0];
1384                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1385                         btrfs_release_path(root, path);
1386                         continue;
1387                 }
1388
1389                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1390                 if (key.objectid != BTRFS_DEV_ITEMS_OBJECTID ||
1391                     key.type != BTRFS_DEV_ITEM_KEY)
1392                         break;
1393
1394                 dev_item = btrfs_item_ptr(leaf, path->slots[0],
1395                                           struct btrfs_dev_item);
1396                 devid = btrfs_device_id(leaf, dev_item);
1397                 read_extent_buffer(leaf, dev_uuid,
1398                                    (unsigned long)btrfs_device_uuid(dev_item),
1399                                    BTRFS_UUID_SIZE);
1400                 read_extent_buffer(leaf, fs_uuid,
1401                                    (unsigned long)btrfs_device_fsid(dev_item),
1402                                    BTRFS_UUID_SIZE);
1403                 device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
1404                 BUG_ON(!device);
1405
1406                 if (device->fs_devices->seeding) {
1407                         btrfs_set_device_generation(leaf, dev_item,
1408                                                     device->generation);
1409                         btrfs_mark_buffer_dirty(leaf);
1410                 }
1411
1412                 path->slots[0]++;
1413                 goto next_slot;
1414         }
1415         ret = 0;
1416 error:
1417         btrfs_free_path(path);
1418         return ret;
1419 }
1420
1421 int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
1422 {
1423         struct btrfs_trans_handle *trans;
1424         struct btrfs_device *device;
1425         struct block_device *bdev;
1426         struct list_head *devices;
1427         struct super_block *sb = root->fs_info->sb;
1428         u64 total_bytes;
1429         int seeding_dev = 0;
1430         int ret = 0;
1431
1432         if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
1433                 return -EINVAL;
1434
1435         bdev = open_bdev_exclusive(device_path, 0, root->fs_info->bdev_holder);
1436         if (!bdev)
1437                 return -EIO;
1438
1439         if (root->fs_info->fs_devices->seeding) {
1440                 seeding_dev = 1;
1441                 down_write(&sb->s_umount);
1442                 mutex_lock(&uuid_mutex);
1443         }
1444
1445         filemap_write_and_wait(bdev->bd_inode->i_mapping);
1446         mutex_lock(&root->fs_info->volume_mutex);
1447
1448         devices = &root->fs_info->fs_devices->devices;
1449         /*
1450          * we have the volume lock, so we don't need the extra
1451          * device list mutex while reading the list here.
1452          */
1453         list_for_each_entry(device, devices, dev_list) {
1454                 if (device->bdev == bdev) {
1455                         ret = -EEXIST;
1456                         goto error;
1457                 }
1458         }
1459
1460         device = kzalloc(sizeof(*device), GFP_NOFS);
1461         if (!device) {
1462                 /* we can safely leave the fs_devices entry around */
1463                 ret = -ENOMEM;
1464                 goto error;
1465         }
1466
1467         device->name = kstrdup(device_path, GFP_NOFS);
1468         if (!device->name) {
1469                 kfree(device);
1470                 ret = -ENOMEM;
1471                 goto error;
1472         }
1473
1474         ret = find_next_devid(root, &device->devid);
1475         if (ret) {
1476                 kfree(device);
1477                 goto error;
1478         }
1479
1480         trans = btrfs_start_transaction(root, 1);
1481         lock_chunks(root);
1482
1483         device->barriers = 1;
1484         device->writeable = 1;
1485         device->work.func = pending_bios_fn;
1486         generate_random_uuid(device->uuid);
1487         spin_lock_init(&device->io_lock);
1488         device->generation = trans->transid;
1489         device->io_width = root->sectorsize;
1490         device->io_align = root->sectorsize;
1491         device->sector_size = root->sectorsize;
1492         device->total_bytes = i_size_read(bdev->bd_inode);
1493         device->disk_total_bytes = device->total_bytes;
1494         device->dev_root = root->fs_info->dev_root;
1495         device->bdev = bdev;
1496         device->in_fs_metadata = 1;
1497         device->mode = 0;
1498         set_blocksize(device->bdev, 4096);
1499
1500         if (seeding_dev) {
1501                 sb->s_flags &= ~MS_RDONLY;
1502                 ret = btrfs_prepare_sprout(trans, root);
1503                 BUG_ON(ret);
1504         }
1505
1506         device->fs_devices = root->fs_info->fs_devices;
1507
1508         /*
1509          * we don't want write_supers to jump in here with our device
1510          * half setup
1511          */
1512         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1513         list_add(&device->dev_list, &root->fs_info->fs_devices->devices);
1514         list_add(&device->dev_alloc_list,
1515                  &root->fs_info->fs_devices->alloc_list);
1516         root->fs_info->fs_devices->num_devices++;
1517         root->fs_info->fs_devices->open_devices++;
1518         root->fs_info->fs_devices->rw_devices++;
1519         root->fs_info->fs_devices->total_rw_bytes += device->total_bytes;
1520
1521         if (!blk_queue_nonrot(bdev_get_queue(bdev)))
1522                 root->fs_info->fs_devices->rotating = 1;
1523
1524         total_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
1525         btrfs_set_super_total_bytes(&root->fs_info->super_copy,
1526                                     total_bytes + device->total_bytes);
1527
1528         total_bytes = btrfs_super_num_devices(&root->fs_info->super_copy);
1529         btrfs_set_super_num_devices(&root->fs_info->super_copy,
1530                                     total_bytes + 1);
1531         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1532
1533         if (seeding_dev) {
1534                 ret = init_first_rw_device(trans, root, device);
1535                 BUG_ON(ret);
1536                 ret = btrfs_finish_sprout(trans, root);
1537                 BUG_ON(ret);
1538         } else {
1539                 ret = btrfs_add_device(trans, root, device);
1540         }
1541
1542         /*
1543          * we've got more storage, clear any full flags on the space
1544          * infos
1545          */
1546         btrfs_clear_space_info_full(root->fs_info);
1547
1548         unlock_chunks(root);
1549         btrfs_commit_transaction(trans, root);
1550
1551         if (seeding_dev) {
1552                 mutex_unlock(&uuid_mutex);
1553                 up_write(&sb->s_umount);
1554
1555                 ret = btrfs_relocate_sys_chunks(root);
1556                 BUG_ON(ret);
1557         }
1558 out:
1559         mutex_unlock(&root->fs_info->volume_mutex);
1560         return ret;
1561 error:
1562         close_bdev_exclusive(bdev, 0);
1563         if (seeding_dev) {
1564                 mutex_unlock(&uuid_mutex);
1565                 up_write(&sb->s_umount);
1566         }
1567         goto out;
1568 }
1569
1570 static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
1571                                         struct btrfs_device *device)
1572 {
1573         int ret;
1574         struct btrfs_path *path;
1575         struct btrfs_root *root;
1576         struct btrfs_dev_item *dev_item;
1577         struct extent_buffer *leaf;
1578         struct btrfs_key key;
1579
1580         root = device->dev_root->fs_info->chunk_root;
1581
1582         path = btrfs_alloc_path();
1583         if (!path)
1584                 return -ENOMEM;
1585
1586         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
1587         key.type = BTRFS_DEV_ITEM_KEY;
1588         key.offset = device->devid;
1589
1590         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
1591         if (ret < 0)
1592                 goto out;
1593
1594         if (ret > 0) {
1595                 ret = -ENOENT;
1596                 goto out;
1597         }
1598
1599         leaf = path->nodes[0];
1600         dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
1601
1602         btrfs_set_device_id(leaf, dev_item, device->devid);
1603         btrfs_set_device_type(leaf, dev_item, device->type);
1604         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
1605         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
1606         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
1607         btrfs_set_device_total_bytes(leaf, dev_item, device->disk_total_bytes);
1608         btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
1609         btrfs_mark_buffer_dirty(leaf);
1610
1611 out:
1612         btrfs_free_path(path);
1613         return ret;
1614 }
1615
1616 static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
1617                       struct btrfs_device *device, u64 new_size)
1618 {
1619         struct btrfs_super_block *super_copy =
1620                 &device->dev_root->fs_info->super_copy;
1621         u64 old_total = btrfs_super_total_bytes(super_copy);
1622         u64 diff = new_size - device->total_bytes;
1623
1624         if (!device->writeable)
1625                 return -EACCES;
1626         if (new_size <= device->total_bytes)
1627                 return -EINVAL;
1628
1629         btrfs_set_super_total_bytes(super_copy, old_total + diff);
1630         device->fs_devices->total_rw_bytes += diff;
1631
1632         device->total_bytes = new_size;
1633         device->disk_total_bytes = new_size;
1634         btrfs_clear_space_info_full(device->dev_root->fs_info);
1635
1636         return btrfs_update_device(trans, device);
1637 }
1638
1639 int btrfs_grow_device(struct btrfs_trans_handle *trans,
1640                       struct btrfs_device *device, u64 new_size)
1641 {
1642         int ret;
1643         lock_chunks(device->dev_root);
1644         ret = __btrfs_grow_device(trans, device, new_size);
1645         unlock_chunks(device->dev_root);
1646         return ret;
1647 }
1648
1649 static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
1650                             struct btrfs_root *root,
1651                             u64 chunk_tree, u64 chunk_objectid,
1652                             u64 chunk_offset)
1653 {
1654         int ret;
1655         struct btrfs_path *path;
1656         struct btrfs_key key;
1657
1658         root = root->fs_info->chunk_root;
1659         path = btrfs_alloc_path();
1660         if (!path)
1661                 return -ENOMEM;
1662
1663         key.objectid = chunk_objectid;
1664         key.offset = chunk_offset;
1665         key.type = BTRFS_CHUNK_ITEM_KEY;
1666
1667         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1668         BUG_ON(ret);
1669
1670         ret = btrfs_del_item(trans, root, path);
1671         BUG_ON(ret);
1672
1673         btrfs_free_path(path);
1674         return 0;
1675 }
1676
1677 static int btrfs_del_sys_chunk(struct btrfs_root *root, u64 chunk_objectid, u64
1678                         chunk_offset)
1679 {
1680         struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
1681         struct btrfs_disk_key *disk_key;
1682         struct btrfs_chunk *chunk;
1683         u8 *ptr;
1684         int ret = 0;
1685         u32 num_stripes;
1686         u32 array_size;
1687         u32 len = 0;
1688         u32 cur;
1689         struct btrfs_key key;
1690
1691         array_size = btrfs_super_sys_array_size(super_copy);
1692
1693         ptr = super_copy->sys_chunk_array;
1694         cur = 0;
1695
1696         while (cur < array_size) {
1697                 disk_key = (struct btrfs_disk_key *)ptr;
1698                 btrfs_disk_key_to_cpu(&key, disk_key);
1699
1700                 len = sizeof(*disk_key);
1701
1702                 if (key.type == BTRFS_CHUNK_ITEM_KEY) {
1703                         chunk = (struct btrfs_chunk *)(ptr + len);
1704                         num_stripes = btrfs_stack_chunk_num_stripes(chunk);
1705                         len += btrfs_chunk_item_size(num_stripes);
1706                 } else {
1707                         ret = -EIO;
1708                         break;
1709                 }
1710                 if (key.objectid == chunk_objectid &&
1711                     key.offset == chunk_offset) {
1712                         memmove(ptr, ptr + len, array_size - (cur + len));
1713                         array_size -= len;
1714                         btrfs_set_super_sys_array_size(super_copy, array_size);
1715                 } else {
1716                         ptr += len;
1717                         cur += len;
1718                 }
1719         }
1720         return ret;
1721 }
1722
1723 static int btrfs_relocate_chunk(struct btrfs_root *root,
1724                          u64 chunk_tree, u64 chunk_objectid,
1725                          u64 chunk_offset)
1726 {
1727         struct extent_map_tree *em_tree;
1728         struct btrfs_root *extent_root;
1729         struct btrfs_trans_handle *trans;
1730         struct extent_map *em;
1731         struct map_lookup *map;
1732         int ret;
1733         int i;
1734
1735         root = root->fs_info->chunk_root;
1736         extent_root = root->fs_info->extent_root;
1737         em_tree = &root->fs_info->mapping_tree.map_tree;
1738
1739         /* step one, relocate all the extents inside this chunk */
1740         ret = btrfs_relocate_block_group(extent_root, chunk_offset);
1741         BUG_ON(ret);
1742
1743         trans = btrfs_start_transaction(root, 1);
1744         BUG_ON(!trans);
1745
1746         lock_chunks(root);
1747
1748         /*
1749          * step two, delete the device extents and the
1750          * chunk tree entries
1751          */
1752         spin_lock(&em_tree->lock);
1753         em = lookup_extent_mapping(em_tree, chunk_offset, 1);
1754         spin_unlock(&em_tree->lock);
1755
1756         BUG_ON(em->start > chunk_offset ||
1757                em->start + em->len < chunk_offset);
1758         map = (struct map_lookup *)em->bdev;
1759
1760         for (i = 0; i < map->num_stripes; i++) {
1761                 ret = btrfs_free_dev_extent(trans, map->stripes[i].dev,
1762                                             map->stripes[i].physical);
1763                 BUG_ON(ret);
1764
1765                 if (map->stripes[i].dev) {
1766                         ret = btrfs_update_device(trans, map->stripes[i].dev);
1767                         BUG_ON(ret);
1768                 }
1769         }
1770         ret = btrfs_free_chunk(trans, root, chunk_tree, chunk_objectid,
1771                                chunk_offset);
1772
1773         BUG_ON(ret);
1774
1775         if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
1776                 ret = btrfs_del_sys_chunk(root, chunk_objectid, chunk_offset);
1777                 BUG_ON(ret);
1778         }
1779
1780         ret = btrfs_remove_block_group(trans, extent_root, chunk_offset);
1781         BUG_ON(ret);
1782
1783         spin_lock(&em_tree->lock);
1784         remove_extent_mapping(em_tree, em);
1785         spin_unlock(&em_tree->lock);
1786
1787         kfree(map);
1788         em->bdev = NULL;
1789
1790         /* once for the tree */
1791         free_extent_map(em);
1792         /* once for us */
1793         free_extent_map(em);
1794
1795         unlock_chunks(root);
1796         btrfs_end_transaction(trans, root);
1797         return 0;
1798 }
1799
1800 static int btrfs_relocate_sys_chunks(struct btrfs_root *root)
1801 {
1802         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
1803         struct btrfs_path *path;
1804         struct extent_buffer *leaf;
1805         struct btrfs_chunk *chunk;
1806         struct btrfs_key key;
1807         struct btrfs_key found_key;
1808         u64 chunk_tree = chunk_root->root_key.objectid;
1809         u64 chunk_type;
1810         int ret;
1811
1812         path = btrfs_alloc_path();
1813         if (!path)
1814                 return -ENOMEM;
1815
1816         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
1817         key.offset = (u64)-1;
1818         key.type = BTRFS_CHUNK_ITEM_KEY;
1819
1820         while (1) {
1821                 ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
1822                 if (ret < 0)
1823                         goto error;
1824                 BUG_ON(ret == 0);
1825
1826                 ret = btrfs_previous_item(chunk_root, path, key.objectid,
1827                                           key.type);
1828                 if (ret < 0)
1829                         goto error;
1830                 if (ret > 0)
1831                         break;
1832
1833                 leaf = path->nodes[0];
1834                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1835
1836                 chunk = btrfs_item_ptr(leaf, path->slots[0],
1837                                        struct btrfs_chunk);
1838                 chunk_type = btrfs_chunk_type(leaf, chunk);
1839                 btrfs_release_path(chunk_root, path);
1840
1841                 if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM) {
1842                         ret = btrfs_relocate_chunk(chunk_root, chunk_tree,
1843                                                    found_key.objectid,
1844                                                    found_key.offset);
1845                         BUG_ON(ret);
1846                 }
1847
1848                 if (found_key.offset == 0)
1849                         break;
1850                 key.offset = found_key.offset - 1;
1851         }
1852         ret = 0;
1853 error:
1854         btrfs_free_path(path);
1855         return ret;
1856 }
1857
1858 static u64 div_factor(u64 num, int factor)
1859 {
1860         if (factor == 10)
1861                 return num;
1862         num *= factor;
1863         do_div(num, 10);
1864         return num;
1865 }
1866
1867 int btrfs_balance(struct btrfs_root *dev_root)
1868 {
1869         int ret;
1870         struct list_head *devices = &dev_root->fs_info->fs_devices->devices;
1871         struct btrfs_device *device;
1872         u64 old_size;
1873         u64 size_to_free;
1874         struct btrfs_path *path;
1875         struct btrfs_key key;
1876         struct btrfs_chunk *chunk;
1877         struct btrfs_root *chunk_root = dev_root->fs_info->chunk_root;
1878         struct btrfs_trans_handle *trans;
1879         struct btrfs_key found_key;
1880
1881         if (dev_root->fs_info->sb->s_flags & MS_RDONLY)
1882                 return -EROFS;
1883
1884         mutex_lock(&dev_root->fs_info->volume_mutex);
1885         dev_root = dev_root->fs_info->dev_root;
1886
1887         /* step one make some room on all the devices */
1888         list_for_each_entry(device, devices, dev_list) {
1889                 old_size = device->total_bytes;
1890                 size_to_free = div_factor(old_size, 1);
1891                 size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
1892                 if (!device->writeable ||
1893                     device->total_bytes - device->bytes_used > size_to_free)
1894                         continue;
1895
1896                 ret = btrfs_shrink_device(device, old_size - size_to_free);
1897                 BUG_ON(ret);
1898
1899                 trans = btrfs_start_transaction(dev_root, 1);
1900                 BUG_ON(!trans);
1901
1902                 ret = btrfs_grow_device(trans, device, old_size);
1903                 BUG_ON(ret);
1904
1905                 btrfs_end_transaction(trans, dev_root);
1906         }
1907
1908         /* step two, relocate all the chunks */
1909         path = btrfs_alloc_path();
1910         BUG_ON(!path);
1911
1912         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
1913         key.offset = (u64)-1;
1914         key.type = BTRFS_CHUNK_ITEM_KEY;
1915
1916         while (1) {
1917                 ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
1918                 if (ret < 0)
1919                         goto error;
1920
1921                 /*
1922                  * this shouldn't happen, it means the last relocate
1923                  * failed
1924                  */
1925                 if (ret == 0)
1926                         break;
1927
1928                 ret = btrfs_previous_item(chunk_root, path, 0,
1929                                           BTRFS_CHUNK_ITEM_KEY);
1930                 if (ret)
1931                         break;
1932
1933                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
1934                                       path->slots[0]);
1935                 if (found_key.objectid != key.objectid)
1936                         break;
1937
1938                 chunk = btrfs_item_ptr(path->nodes[0],
1939                                        path->slots[0],
1940                                        struct btrfs_chunk);
1941                 key.offset = found_key.offset;
1942                 /* chunk zero is special */
1943                 if (key.offset == 0)
1944                         break;
1945
1946                 btrfs_release_path(chunk_root, path);
1947                 ret = btrfs_relocate_chunk(chunk_root,
1948                                            chunk_root->root_key.objectid,
1949                                            found_key.objectid,
1950                                            found_key.offset);
1951                 BUG_ON(ret);
1952         }
1953         ret = 0;
1954 error:
1955         btrfs_free_path(path);
1956         mutex_unlock(&dev_root->fs_info->volume_mutex);
1957         return ret;
1958 }
1959
1960 /*
1961  * shrinking a device means finding all of the device extents past
1962  * the new size, and then following the back refs to the chunks.
1963  * The chunk relocation code actually frees the device extent
1964  */
1965 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
1966 {
1967         struct btrfs_trans_handle *trans;
1968         struct btrfs_root *root = device->dev_root;
1969         struct btrfs_dev_extent *dev_extent = NULL;
1970         struct btrfs_path *path;
1971         u64 length;
1972         u64 chunk_tree;
1973         u64 chunk_objectid;
1974         u64 chunk_offset;
1975         int ret;
1976         int slot;
1977         struct extent_buffer *l;
1978         struct btrfs_key key;
1979         struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
1980         u64 old_total = btrfs_super_total_bytes(super_copy);
1981         u64 diff = device->total_bytes - new_size;
1982
1983         if (new_size >= device->total_bytes)
1984                 return -EINVAL;
1985
1986         path = btrfs_alloc_path();
1987         if (!path)
1988                 return -ENOMEM;
1989
1990         trans = btrfs_start_transaction(root, 1);
1991         if (!trans) {
1992                 ret = -ENOMEM;
1993                 goto done;
1994         }
1995
1996         path->reada = 2;
1997
1998         lock_chunks(root);
1999
2000         device->total_bytes = new_size;
2001         if (device->writeable)
2002                 device->fs_devices->total_rw_bytes -= diff;
2003         unlock_chunks(root);
2004         btrfs_end_transaction(trans, root);
2005
2006         key.objectid = device->devid;
2007         key.offset = (u64)-1;
2008         key.type = BTRFS_DEV_EXTENT_KEY;
2009
2010         while (1) {
2011                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2012                 if (ret < 0)
2013                         goto done;
2014
2015                 ret = btrfs_previous_item(root, path, 0, key.type);
2016                 if (ret < 0)
2017                         goto done;
2018                 if (ret) {
2019                         ret = 0;
2020                         break;
2021                 }
2022
2023                 l = path->nodes[0];
2024                 slot = path->slots[0];
2025                 btrfs_item_key_to_cpu(l, &key, path->slots[0]);
2026
2027                 if (key.objectid != device->devid)
2028                         break;
2029
2030                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
2031                 length = btrfs_dev_extent_length(l, dev_extent);
2032
2033                 if (key.offset + length <= new_size)
2034                         break;
2035
2036                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
2037                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
2038                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
2039                 btrfs_release_path(root, path);
2040
2041                 ret = btrfs_relocate_chunk(root, chunk_tree, chunk_objectid,
2042                                            chunk_offset);
2043                 if (ret)
2044                         goto done;
2045         }
2046
2047         /* Shrinking succeeded, else we would be at "done". */
2048         trans = btrfs_start_transaction(root, 1);
2049         if (!trans) {
2050                 ret = -ENOMEM;
2051                 goto done;
2052         }
2053         lock_chunks(root);
2054
2055         device->disk_total_bytes = new_size;
2056         /* Now btrfs_update_device() will change the on-disk size. */
2057         ret = btrfs_update_device(trans, device);
2058         if (ret) {
2059                 unlock_chunks(root);
2060                 btrfs_end_transaction(trans, root);
2061                 goto done;
2062         }
2063         WARN_ON(diff > old_total);
2064         btrfs_set_super_total_bytes(super_copy, old_total - diff);
2065         unlock_chunks(root);
2066         btrfs_end_transaction(trans, root);
2067 done:
2068         btrfs_free_path(path);
2069         return ret;
2070 }
2071
2072 static int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
2073                            struct btrfs_root *root,
2074                            struct btrfs_key *key,
2075                            struct btrfs_chunk *chunk, int item_size)
2076 {
2077         struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
2078         struct btrfs_disk_key disk_key;
2079         u32 array_size;
2080         u8 *ptr;
2081
2082         array_size = btrfs_super_sys_array_size(super_copy);
2083         if (array_size + item_size > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE)
2084                 return -EFBIG;
2085
2086         ptr = super_copy->sys_chunk_array + array_size;
2087         btrfs_cpu_key_to_disk(&disk_key, key);
2088         memcpy(ptr, &disk_key, sizeof(disk_key));
2089         ptr += sizeof(disk_key);
2090         memcpy(ptr, chunk, item_size);
2091         item_size += sizeof(disk_key);
2092         btrfs_set_super_sys_array_size(super_copy, array_size + item_size);
2093         return 0;
2094 }
2095
2096 static noinline u64 chunk_bytes_by_type(u64 type, u64 calc_size,
2097                                         int num_stripes, int sub_stripes)
2098 {
2099         if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
2100                 return calc_size;
2101         else if (type & BTRFS_BLOCK_GROUP_RAID10)
2102                 return calc_size * (num_stripes / sub_stripes);
2103         else
2104                 return calc_size * num_stripes;
2105 }
2106
2107 static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
2108                                struct btrfs_root *extent_root,
2109                                struct map_lookup **map_ret,
2110                                u64 *num_bytes, u64 *stripe_size,
2111                                u64 start, u64 type)
2112 {
2113         struct btrfs_fs_info *info = extent_root->fs_info;
2114         struct btrfs_device *device = NULL;
2115         struct btrfs_fs_devices *fs_devices = info->fs_devices;
2116         struct list_head *cur;
2117         struct map_lookup *map = NULL;
2118         struct extent_map_tree *em_tree;
2119         struct extent_map *em;
2120         struct list_head private_devs;
2121         int min_stripe_size = 1 * 1024 * 1024;
2122         u64 calc_size = 1024 * 1024 * 1024;
2123         u64 max_chunk_size = calc_size;
2124         u64 min_free;
2125         u64 avail;
2126         u64 max_avail = 0;
2127         u64 dev_offset;
2128         int num_stripes = 1;
2129         int min_stripes = 1;
2130         int sub_stripes = 0;
2131         int looped = 0;
2132         int ret;
2133         int index;
2134         int stripe_len = 64 * 1024;
2135
2136         if ((type & BTRFS_BLOCK_GROUP_RAID1) &&
2137             (type & BTRFS_BLOCK_GROUP_DUP)) {
2138                 WARN_ON(1);
2139                 type &= ~BTRFS_BLOCK_GROUP_DUP;
2140         }
2141         if (list_empty(&fs_devices->alloc_list))
2142                 return -ENOSPC;
2143
2144         if (type & (BTRFS_BLOCK_GROUP_RAID0)) {
2145                 num_stripes = fs_devices->rw_devices;
2146                 min_stripes = 2;
2147         }
2148         if (type & (BTRFS_BLOCK_GROUP_DUP)) {
2149                 num_stripes = 2;
2150                 min_stripes = 2;
2151         }
2152         if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
2153                 num_stripes = min_t(u64, 2, fs_devices->rw_devices);
2154                 if (num_stripes < 2)
2155                         return -ENOSPC;
2156                 min_stripes = 2;
2157         }
2158         if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
2159                 num_stripes = fs_devices->rw_devices;
2160                 if (num_stripes < 4)
2161                         return -ENOSPC;
2162                 num_stripes &= ~(u32)1;
2163                 sub_stripes = 2;
2164                 min_stripes = 4;
2165         }
2166
2167         if (type & BTRFS_BLOCK_GROUP_DATA) {
2168                 max_chunk_size = 10 * calc_size;
2169                 min_stripe_size = 64 * 1024 * 1024;
2170         } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
2171                 max_chunk_size = 4 * calc_size;
2172                 min_stripe_size = 32 * 1024 * 1024;
2173         } else if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
2174                 calc_size = 8 * 1024 * 1024;
2175                 max_chunk_size = calc_size * 2;
2176                 min_stripe_size = 1 * 1024 * 1024;
2177         }
2178
2179         /* we don't want a chunk larger than 10% of writeable space */
2180         max_chunk_size = min(div_factor(fs_devices->total_rw_bytes, 1),
2181                              max_chunk_size);
2182
2183 again:
2184         max_avail = 0;
2185         if (!map || map->num_stripes != num_stripes) {
2186                 kfree(map);
2187                 map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
2188                 if (!map)
2189                         return -ENOMEM;
2190                 map->num_stripes = num_stripes;
2191         }
2192
2193         if (calc_size * num_stripes > max_chunk_size) {
2194                 calc_size = max_chunk_size;
2195                 do_div(calc_size, num_stripes);
2196                 do_div(calc_size, stripe_len);
2197                 calc_size *= stripe_len;
2198         }
2199         /* we don't want tiny stripes */
2200         calc_size = max_t(u64, min_stripe_size, calc_size);
2201
2202         do_div(calc_size, stripe_len);
2203         calc_size *= stripe_len;
2204
2205         cur = fs_devices->alloc_list.next;
2206         index = 0;
2207
2208         if (type & BTRFS_BLOCK_GROUP_DUP)
2209                 min_free = calc_size * 2;
2210         else
2211                 min_free = calc_size;
2212
2213         /*
2214          * we add 1MB because we never use the first 1MB of the device, unless
2215          * we've looped, then we are likely allocating the maximum amount of
2216          * space left already
2217          */
2218         if (!looped)
2219                 min_free += 1024 * 1024;
2220
2221         INIT_LIST_HEAD(&private_devs);
2222         while (index < num_stripes) {
2223                 device = list_entry(cur, struct btrfs_device, dev_alloc_list);
2224                 BUG_ON(!device->writeable);
2225                 if (device->total_bytes > device->bytes_used)
2226                         avail = device->total_bytes - device->bytes_used;
2227                 else
2228                         avail = 0;
2229                 cur = cur->next;
2230
2231                 if (device->in_fs_metadata && avail >= min_free) {
2232                         ret = find_free_dev_extent(trans, device,
2233                                                    min_free, &dev_offset,
2234                                                    &max_avail);
2235                         if (ret == 0) {
2236                                 list_move_tail(&device->dev_alloc_list,
2237                                                &private_devs);
2238                                 map->stripes[index].dev = device;
2239                                 map->stripes[index].physical = dev_offset;
2240                                 index++;
2241                                 if (type & BTRFS_BLOCK_GROUP_DUP) {
2242                                         map->stripes[index].dev = device;
2243                                         map->stripes[index].physical =
2244                                                 dev_offset + calc_size;
2245                                         index++;
2246                                 }
2247                         }
2248                 } else if (device->in_fs_metadata && avail > max_avail)
2249                         max_avail = avail;
2250                 if (cur == &fs_devices->alloc_list)
2251                         break;
2252         }
2253         list_splice(&private_devs, &fs_devices->alloc_list);
2254         if (index < num_stripes) {
2255                 if (index >= min_stripes) {
2256                         num_stripes = index;
2257                         if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
2258                                 num_stripes /= sub_stripes;
2259                                 num_stripes *= sub_stripes;
2260                         }
2261                         looped = 1;
2262                         goto again;
2263                 }
2264                 if (!looped && max_avail > 0) {
2265                         looped = 1;
2266                         calc_size = max_avail;
2267                         goto again;
2268                 }
2269                 kfree(map);
2270                 return -ENOSPC;
2271         }
2272         map->sector_size = extent_root->sectorsize;
2273         map->stripe_len = stripe_len;
2274         map->io_align = stripe_len;
2275         map->io_width = stripe_len;
2276         map->type = type;
2277         map->num_stripes = num_stripes;
2278         map->sub_stripes = sub_stripes;
2279
2280         *map_ret = map;
2281         *stripe_size = calc_size;
2282         *num_bytes = chunk_bytes_by_type(type, calc_size,
2283                                          num_stripes, sub_stripes);
2284
2285         em = alloc_extent_map(GFP_NOFS);
2286         if (!em) {
2287                 kfree(map);
2288                 return -ENOMEM;
2289         }
2290         em->bdev = (struct block_device *)map;
2291         em->start = start;
2292         em->len = *num_bytes;
2293         em->block_start = 0;
2294         em->block_len = em->len;
2295
2296         em_tree = &extent_root->fs_info->mapping_tree.map_tree;
2297         spin_lock(&em_tree->lock);
2298         ret = add_extent_mapping(em_tree, em);
2299         spin_unlock(&em_tree->lock);
2300         BUG_ON(ret);
2301         free_extent_map(em);
2302
2303         ret = btrfs_make_block_group(trans, extent_root, 0, type,
2304                                      BTRFS_FIRST_CHUNK_TREE_OBJECTID,
2305                                      start, *num_bytes);
2306         BUG_ON(ret);
2307
2308         index = 0;
2309         while (index < map->num_stripes) {
2310                 device = map->stripes[index].dev;
2311                 dev_offset = map->stripes[index].physical;
2312
2313                 ret = btrfs_alloc_dev_extent(trans, device,
2314                                 info->chunk_root->root_key.objectid,
2315                                 BTRFS_FIRST_CHUNK_TREE_OBJECTID,
2316                                 start, dev_offset, calc_size);
2317                 BUG_ON(ret);
2318                 index++;
2319         }
2320
2321         return 0;
2322 }
2323
2324 static int __finish_chunk_alloc(struct btrfs_trans_handle *trans,
2325                                 struct btrfs_root *extent_root,
2326                                 struct map_lookup *map, u64 chunk_offset,
2327                                 u64 chunk_size, u64 stripe_size)
2328 {
2329         u64 dev_offset;
2330         struct btrfs_key key;
2331         struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
2332         struct btrfs_device *device;
2333         struct btrfs_chunk *chunk;
2334         struct btrfs_stripe *stripe;
2335         size_t item_size = btrfs_chunk_item_size(map->num_stripes);
2336         int index = 0;
2337         int ret;
2338
2339         chunk = kzalloc(item_size, GFP_NOFS);
2340         if (!chunk)
2341                 return -ENOMEM;
2342
2343         index = 0;
2344         while (index < map->num_stripes) {
2345                 device = map->stripes[index].dev;
2346                 device->bytes_used += stripe_size;
2347                 ret = btrfs_update_device(trans, device);
2348                 BUG_ON(ret);
2349                 index++;
2350         }
2351
2352         index = 0;
2353         stripe = &chunk->stripe;
2354         while (index < map->num_stripes) {
2355                 device = map->stripes[index].dev;
2356                 dev_offset = map->stripes[index].physical;
2357
2358                 btrfs_set_stack_stripe_devid(stripe, device->devid);
2359                 btrfs_set_stack_stripe_offset(stripe, dev_offset);
2360                 memcpy(stripe->dev_uuid, device->uuid, BTRFS_UUID_SIZE);
2361                 stripe++;
2362                 index++;
2363         }
2364
2365         btrfs_set_stack_chunk_length(chunk, chunk_size);
2366         btrfs_set_stack_chunk_owner(chunk, extent_root->root_key.objectid);
2367         btrfs_set_stack_chunk_stripe_len(chunk, map->stripe_len);
2368         btrfs_set_stack_chunk_type(chunk, map->type);
2369         btrfs_set_stack_chunk_num_stripes(chunk, map->num_stripes);
2370         btrfs_set_stack_chunk_io_align(chunk, map->stripe_len);
2371         btrfs_set_stack_chunk_io_width(chunk, map->stripe_len);
2372         btrfs_set_stack_chunk_sector_size(chunk, extent_root->sectorsize);
2373         btrfs_set_stack_chunk_sub_stripes(chunk, map->sub_stripes);
2374
2375         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
2376         key.type = BTRFS_CHUNK_ITEM_KEY;
2377         key.offset = chunk_offset;
2378
2379         ret = btrfs_insert_item(trans, chunk_root, &key, chunk, item_size);
2380         BUG_ON(ret);
2381
2382         if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
2383                 ret = btrfs_add_system_chunk(trans, chunk_root, &key, chunk,
2384                                              item_size);
2385                 BUG_ON(ret);
2386         }
2387         kfree(chunk);
2388         return 0;
2389 }
2390
2391 /*
2392  * Chunk allocation falls into two parts. The first part does works
2393  * that make the new allocated chunk useable, but not do any operation
2394  * that modifies the chunk tree. The second part does the works that
2395  * require modifying the chunk tree. This division is important for the
2396  * bootstrap process of adding storage to a seed btrfs.
2397  */
2398 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
2399                       struct btrfs_root *extent_root, u64 type)
2400 {
2401         u64 chunk_offset;
2402         u64 chunk_size;
2403         u64 stripe_size;
2404         struct map_lookup *map;
2405         struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
2406         int ret;
2407
2408         ret = find_next_chunk(chunk_root, BTRFS_FIRST_CHUNK_TREE_OBJECTID,
2409                               &chunk_offset);
2410         if (ret)
2411                 return ret;
2412
2413         ret = __btrfs_alloc_chunk(trans, extent_root, &map, &chunk_size,
2414                                   &stripe_size, chunk_offset, type);
2415         if (ret)
2416                 return ret;
2417
2418         ret = __finish_chunk_alloc(trans, extent_root, map, chunk_offset,
2419                                    chunk_size, stripe_size);
2420         BUG_ON(ret);
2421         return 0;
2422 }
2423
2424 static noinline int init_first_rw_device(struct btrfs_trans_handle *trans,
2425                                          struct btrfs_root *root,
2426                                          struct btrfs_device *device)
2427 {
2428         u64 chunk_offset;
2429         u64 sys_chunk_offset;
2430         u64 chunk_size;
2431         u64 sys_chunk_size;
2432         u64 stripe_size;
2433         u64 sys_stripe_size;
2434         u64 alloc_profile;
2435         struct map_lookup *map;
2436         struct map_lookup *sys_map;
2437         struct btrfs_fs_info *fs_info = root->fs_info;
2438         struct btrfs_root *extent_root = fs_info->extent_root;
2439         int ret;
2440
2441         ret = find_next_chunk(fs_info->chunk_root,
2442                               BTRFS_FIRST_CHUNK_TREE_OBJECTID, &chunk_offset);
2443         BUG_ON(ret);
2444
2445         alloc_profile = BTRFS_BLOCK_GROUP_METADATA |
2446                         (fs_info->metadata_alloc_profile &
2447                          fs_info->avail_metadata_alloc_bits);
2448         alloc_profile = btrfs_reduce_alloc_profile(root, alloc_profile);
2449
2450         ret = __btrfs_alloc_chunk(trans, extent_root, &map, &chunk_size,
2451                                   &stripe_size, chunk_offset, alloc_profile);
2452         BUG_ON(ret);
2453
2454         sys_chunk_offset = chunk_offset + chunk_size;
2455
2456         alloc_profile = BTRFS_BLOCK_GROUP_SYSTEM |
2457                         (fs_info->system_alloc_profile &
2458                          fs_info->avail_system_alloc_bits);
2459         alloc_profile = btrfs_reduce_alloc_profile(root, alloc_profile);
2460
2461         ret = __btrfs_alloc_chunk(trans, extent_root, &sys_map,
2462                                   &sys_chunk_size, &sys_stripe_size,
2463                                   sys_chunk_offset, alloc_profile);
2464         BUG_ON(ret);
2465
2466         ret = btrfs_add_device(trans, fs_info->chunk_root, device);
2467         BUG_ON(ret);
2468
2469         /*
2470          * Modifying chunk tree needs allocating new blocks from both
2471          * system block group and metadata block group. So we only can
2472          * do operations require modifying the chunk tree after both
2473          * block groups were created.
2474          */
2475         ret = __finish_chunk_alloc(trans, extent_root, map, chunk_offset,
2476                                    chunk_size, stripe_size);
2477         BUG_ON(ret);
2478
2479         ret = __finish_chunk_alloc(trans, extent_root, sys_map,
2480                                    sys_chunk_offset, sys_chunk_size,
2481                                    sys_stripe_size);
2482         BUG_ON(ret);
2483         return 0;
2484 }
2485
2486 int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset)
2487 {
2488         struct extent_map *em;
2489         struct map_lookup *map;
2490         struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
2491         int readonly = 0;
2492         int i;
2493
2494         spin_lock(&map_tree->map_tree.lock);
2495         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
2496         spin_unlock(&map_tree->map_tree.lock);
2497         if (!em)
2498                 return 1;
2499
2500         map = (struct map_lookup *)em->bdev;
2501         for (i = 0; i < map->num_stripes; i++) {
2502                 if (!map->stripes[i].dev->writeable) {
2503                         readonly = 1;
2504                         break;
2505                 }
2506         }
2507         free_extent_map(em);
2508         return readonly;
2509 }
2510
2511 void btrfs_mapping_init(struct btrfs_mapping_tree *tree)
2512 {
2513         extent_map_tree_init(&tree->map_tree, GFP_NOFS);
2514 }
2515
2516 void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree)
2517 {
2518         struct extent_map *em;
2519
2520         while (1) {
2521                 spin_lock(&tree->map_tree.lock);
2522                 em = lookup_extent_mapping(&tree->map_tree, 0, (u64)-1);
2523                 if (em)
2524                         remove_extent_mapping(&tree->map_tree, em);
2525                 spin_unlock(&tree->map_tree.lock);
2526                 if (!em)
2527                         break;
2528                 kfree(em->bdev);
2529                 /* once for us */
2530                 free_extent_map(em);
2531                 /* once for the tree */
2532                 free_extent_map(em);
2533         }
2534 }
2535
2536 int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len)
2537 {
2538         struct extent_map *em;
2539         struct map_lookup *map;
2540         struct extent_map_tree *em_tree = &map_tree->map_tree;
2541         int ret;
2542
2543         spin_lock(&em_tree->lock);
2544         em = lookup_extent_mapping(em_tree, logical, len);
2545         spin_unlock(&em_tree->lock);
2546         BUG_ON(!em);
2547
2548         BUG_ON(em->start > logical || em->start + em->len < logical);
2549         map = (struct map_lookup *)em->bdev;
2550         if (map->type & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1))
2551                 ret = map->num_stripes;
2552         else if (map->type & BTRFS_BLOCK_GROUP_RAID10)
2553                 ret = map->sub_stripes;
2554         else
2555                 ret = 1;
2556         free_extent_map(em);
2557         return ret;
2558 }
2559
2560 static int find_live_mirror(struct map_lookup *map, int first, int num,
2561                             int optimal)
2562 {
2563         int i;
2564         if (map->stripes[optimal].dev->bdev)
2565                 return optimal;
2566         for (i = first; i < first + num; i++) {
2567                 if (map->stripes[i].dev->bdev)
2568                         return i;
2569         }
2570         /* we couldn't find one that doesn't fail.  Just return something
2571          * and the io error handling code will clean up eventually
2572          */
2573         return optimal;
2574 }
2575
2576 static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
2577                              u64 logical, u64 *length,
2578                              struct btrfs_multi_bio **multi_ret,
2579                              int mirror_num, struct page *unplug_page)
2580 {
2581         struct extent_map *em;
2582         struct map_lookup *map;
2583         struct extent_map_tree *em_tree = &map_tree->map_tree;
2584         u64 offset;
2585         u64 stripe_offset;
2586         u64 stripe_nr;
2587         int stripes_allocated = 8;
2588         int stripes_required = 1;
2589         int stripe_index;
2590         int i;
2591         int num_stripes;
2592         int max_errors = 0;
2593         struct btrfs_multi_bio *multi = NULL;
2594
2595         if (multi_ret && !(rw & (1 << BIO_RW)))
2596                 stripes_allocated = 1;
2597 again:
2598         if (multi_ret) {
2599                 multi = kzalloc(btrfs_multi_bio_size(stripes_allocated),
2600                                 GFP_NOFS);
2601                 if (!multi)
2602                         return -ENOMEM;
2603
2604                 atomic_set(&multi->error, 0);
2605         }
2606
2607         spin_lock(&em_tree->lock);
2608         em = lookup_extent_mapping(em_tree, logical, *length);
2609         spin_unlock(&em_tree->lock);
2610
2611         if (!em && unplug_page)
2612                 return 0;
2613
2614         if (!em) {
2615                 printk(KERN_CRIT "unable to find logical %llu len %llu\n",
2616                        (unsigned long long)logical,
2617                        (unsigned long long)*length);
2618                 BUG();
2619         }
2620
2621         BUG_ON(em->start > logical || em->start + em->len < logical);
2622         map = (struct map_lookup *)em->bdev;
2623         offset = logical - em->start;
2624
2625         if (mirror_num > map->num_stripes)
2626                 mirror_num = 0;
2627
2628         /* if our multi bio struct is too small, back off and try again */
2629         if (rw & (1 << BIO_RW)) {
2630                 if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
2631                                  BTRFS_BLOCK_GROUP_DUP)) {
2632                         stripes_required = map->num_stripes;
2633                         max_errors = 1;
2634                 } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
2635                         stripes_required = map->sub_stripes;
2636                         max_errors = 1;
2637                 }
2638         }
2639         if (multi_ret && (rw & (1 << BIO_RW)) &&
2640             stripes_allocated < stripes_required) {
2641                 stripes_allocated = map->num_stripes;
2642                 free_extent_map(em);
2643                 kfree(multi);
2644                 goto again;
2645         }
2646         stripe_nr = offset;
2647         /*
2648          * stripe_nr counts the total number of stripes we have to stride
2649          * to get to this block
2650          */
2651         do_div(stripe_nr, map->stripe_len);
2652
2653         stripe_offset = stripe_nr * map->stripe_len;
2654         BUG_ON(offset < stripe_offset);
2655
2656         /* stripe_offset is the offset of this block in its stripe*/
2657         stripe_offset = offset - stripe_offset;
2658
2659         if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
2660                          BTRFS_BLOCK_GROUP_RAID10 |
2661                          BTRFS_BLOCK_GROUP_DUP)) {
2662                 /* we limit the length of each bio to what fits in a stripe */
2663                 *length = min_t(u64, em->len - offset,
2664                               map->stripe_len - stripe_offset);
2665         } else {
2666                 *length = em->len - offset;
2667         }
2668
2669         if (!multi_ret && !unplug_page)
2670                 goto out;
2671
2672         num_stripes = 1;
2673         stripe_index = 0;
2674         if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
2675                 if (unplug_page || (rw & (1 << BIO_RW)))
2676                         num_stripes = map->num_stripes;
2677                 else if (mirror_num)
2678                         stripe_index = mirror_num - 1;
2679                 else {
2680                         stripe_index = find_live_mirror(map, 0,
2681                                             map->num_stripes,
2682                                             current->pid % map->num_stripes);
2683                 }
2684
2685         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
2686                 if (rw & (1 << BIO_RW))
2687                         num_stripes = map->num_stripes;
2688                 else if (mirror_num)
2689                         stripe_index = mirror_num - 1;
2690
2691         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
2692                 int factor = map->num_stripes / map->sub_stripes;
2693
2694                 stripe_index = do_div(stripe_nr, factor);
2695                 stripe_index *= map->sub_stripes;
2696
2697                 if (unplug_page || (rw & (1 << BIO_RW)))
2698                         num_stripes = map->sub_stripes;
2699                 else if (mirror_num)
2700                         stripe_index += mirror_num - 1;
2701                 else {
2702                         stripe_index = find_live_mirror(map, stripe_index,
2703                                               map->sub_stripes, stripe_index +
2704                                               current->pid % map->sub_stripes);
2705                 }
2706         } else {
2707                 /*
2708                  * after this do_div call, stripe_nr is the number of stripes
2709                  * on this device we have to walk to find the data, and
2710                  * stripe_index is the number of our device in the stripe array
2711                  */
2712                 stripe_index = do_div(stripe_nr, map->num_stripes);
2713         }
2714         BUG_ON(stripe_index >= map->num_stripes);
2715
2716         for (i = 0; i < num_stripes; i++) {
2717                 if (unplug_page) {
2718                         struct btrfs_device *device;
2719                         struct backing_dev_info *bdi;
2720
2721                         device = map->stripes[stripe_index].dev;
2722                         if (device->bdev) {
2723                                 bdi = blk_get_backing_dev_info(device->bdev);
2724                                 if (bdi->unplug_io_fn)
2725                                         bdi->unplug_io_fn(bdi, unplug_page);
2726                         }
2727                 } else {
2728                         multi->stripes[i].physical =
2729                                 map->stripes[stripe_index].physical +
2730                                 stripe_offset + stripe_nr * map->stripe_len;
2731                         multi->stripes[i].dev = map->stripes[stripe_index].dev;
2732                 }
2733                 stripe_index++;
2734         }
2735         if (multi_ret) {
2736                 *multi_ret = multi;
2737                 multi->num_stripes = num_stripes;
2738                 multi->max_errors = max_errors;
2739         }
2740 out:
2741         free_extent_map(em);
2742         return 0;
2743 }
2744
2745 int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
2746                       u64 logical, u64 *length,
2747                       struct btrfs_multi_bio **multi_ret, int mirror_num)
2748 {
2749         return __btrfs_map_block(map_tree, rw, logical, length, multi_ret,
2750                                  mirror_num, NULL);
2751 }
2752
2753 int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
2754                      u64 chunk_start, u64 physical, u64 devid,
2755                      u64 **logical, int *naddrs, int *stripe_len)
2756 {
2757         struct extent_map_tree *em_tree = &map_tree->map_tree;
2758         struct extent_map *em;
2759         struct map_lookup *map;
2760         u64 *buf;
2761         u64 bytenr;
2762         u64 length;
2763         u64 stripe_nr;
2764         int i, j, nr = 0;
2765
2766         spin_lock(&em_tree->lock);
2767         em = lookup_extent_mapping(em_tree, chunk_start, 1);
2768         spin_unlock(&em_tree->lock);
2769
2770         BUG_ON(!em || em->start != chunk_start);
2771         map = (struct map_lookup *)em->bdev;
2772
2773         length = em->len;
2774         if (map->type & BTRFS_BLOCK_GROUP_RAID10)
2775                 do_div(length, map->num_stripes / map->sub_stripes);
2776         else if (map->type & BTRFS_BLOCK_GROUP_RAID0)
2777                 do_div(length, map->num_stripes);
2778
2779         buf = kzalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);
2780         BUG_ON(!buf);
2781
2782         for (i = 0; i < map->num_stripes; i++) {
2783                 if (devid && map->stripes[i].dev->devid != devid)
2784                         continue;
2785                 if (map->stripes[i].physical > physical ||
2786                     map->stripes[i].physical + length <= physical)
2787                         continue;
2788
2789                 stripe_nr = physical - map->stripes[i].physical;
2790                 do_div(stripe_nr, map->stripe_len);
2791
2792                 if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
2793                         stripe_nr = stripe_nr * map->num_stripes + i;
2794                         do_div(stripe_nr, map->sub_stripes);
2795                 } else if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
2796                         stripe_nr = stripe_nr * map->num_stripes + i;
2797                 }
2798                 bytenr = chunk_start + stripe_nr * map->stripe_len;
2799                 WARN_ON(nr >= map->num_stripes);
2800                 for (j = 0; j < nr; j++) {
2801                         if (buf[j] == bytenr)
2802                                 break;
2803                 }
2804                 if (j == nr) {
2805                         WARN_ON(nr >= map->num_stripes);
2806                         buf[nr++] = bytenr;
2807                 }
2808         }
2809
2810         *logical = buf;
2811         *naddrs = nr;
2812         *stripe_len = map->stripe_len;
2813
2814         free_extent_map(em);
2815         return 0;
2816 }
2817
2818 int btrfs_unplug_page(struct btrfs_mapping_tree *map_tree,
2819                       u64 logical, struct page *page)
2820 {
2821         u64 length = PAGE_CACHE_SIZE;
2822         return __btrfs_map_block(map_tree, READ, logical, &length,
2823                                  NULL, 0, page);
2824 }
2825
2826 static void end_bio_multi_stripe(struct bio *bio, int err)
2827 {
2828         struct btrfs_multi_bio *multi = bio->bi_private;
2829         int is_orig_bio = 0;
2830
2831         if (err)
2832                 atomic_inc(&multi->error);
2833
2834         if (bio == multi->orig_bio)
2835                 is_orig_bio = 1;
2836
2837         if (atomic_dec_and_test(&multi->stripes_pending)) {
2838                 if (!is_orig_bio) {
2839                         bio_put(bio);
2840                         bio = multi->orig_bio;
2841                 }
2842                 bio->bi_private = multi->private;
2843                 bio->bi_end_io = multi->end_io;
2844                 /* only send an error to the higher layers if it is
2845                  * beyond the tolerance of the multi-bio
2846                  */
2847                 if (atomic_read(&multi->error) > multi->max_errors) {
2848                         err = -EIO;
2849                 } else if (err) {
2850                         /*
2851                          * this bio is actually up to date, we didn't
2852                          * go over the max number of errors
2853                          */
2854                         set_bit(BIO_UPTODATE, &bio->bi_flags);
2855                         err = 0;
2856                 }
2857                 kfree(multi);
2858
2859                 bio_endio(bio, err);
2860         } else if (!is_orig_bio) {
2861                 bio_put(bio);
2862         }
2863 }
2864
2865 struct async_sched {
2866         struct bio *bio;
2867         int rw;
2868         struct btrfs_fs_info *info;
2869         struct btrfs_work work;
2870 };
2871
2872 /*
2873  * see run_scheduled_bios for a description of why bios are collected for
2874  * async submit.
2875  *
2876  * This will add one bio to the pending list for a device and make sure
2877  * the work struct is scheduled.
2878  */
2879 static noinline int schedule_bio(struct btrfs_root *root,
2880                                  struct btrfs_device *device,
2881                                  int rw, struct bio *bio)
2882 {
2883         int should_queue = 1;
2884         struct btrfs_pending_bios *pending_bios;
2885
2886         /* don't bother with additional async steps for reads, right now */
2887         if (!(rw & (1 << BIO_RW))) {
2888                 bio_get(bio);
2889                 submit_bio(rw, bio);
2890                 bio_put(bio);
2891                 return 0;
2892         }
2893
2894         /*
2895          * nr_async_bios allows us to reliably return congestion to the
2896          * higher layers.  Otherwise, the async bio makes it appear we have
2897          * made progress against dirty pages when we've really just put it
2898          * on a queue for later
2899          */
2900         atomic_inc(&root->fs_info->nr_async_bios);
2901         WARN_ON(bio->bi_next);
2902         bio->bi_next = NULL;
2903         bio->bi_rw |= rw;
2904
2905         spin_lock(&device->io_lock);
2906         if (bio_sync(bio))
2907                 pending_bios = &device->pending_sync_bios;
2908         else
2909                 pending_bios = &device->pending_bios;
2910
2911         if (pending_bios->tail)
2912                 pending_bios->tail->bi_next = bio;
2913
2914         pending_bios->tail = bio;
2915         if (!pending_bios->head)
2916                 pending_bios->head = bio;
2917         if (device->running_pending)
2918                 should_queue = 0;
2919
2920         spin_unlock(&device->io_lock);
2921
2922         if (should_queue)
2923                 btrfs_queue_worker(&root->fs_info->submit_workers,
2924                                    &device->work);
2925         return 0;
2926 }
2927
2928 int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
2929                   int mirror_num, int async_submit)
2930 {
2931         struct btrfs_mapping_tree *map_tree;
2932         struct btrfs_device *dev;
2933         struct bio *first_bio = bio;
2934         u64 logical = (u64)bio->bi_sector << 9;
2935         u64 length = 0;
2936         u64 map_length;
2937         struct btrfs_multi_bio *multi = NULL;
2938         int ret;
2939         int dev_nr = 0;
2940         int total_devs = 1;
2941
2942         length = bio->bi_size;
2943         map_tree = &root->fs_info->mapping_tree;
2944         map_length = length;
2945
2946         ret = btrfs_map_block(map_tree, rw, logical, &map_length, &multi,
2947                               mirror_num);
2948         BUG_ON(ret);
2949
2950         total_devs = multi->num_stripes;
2951         if (map_length < length) {
2952                 printk(KERN_CRIT "mapping failed logical %llu bio len %llu "
2953                        "len %llu\n", (unsigned long long)logical,
2954                        (unsigned long long)length,
2955                        (unsigned long long)map_length);
2956                 BUG();
2957         }
2958         multi->end_io = first_bio->bi_end_io;
2959         multi->private = first_bio->bi_private;
2960         multi->orig_bio = first_bio;
2961         atomic_set(&multi->stripes_pending, multi->num_stripes);
2962
2963         while (dev_nr < total_devs) {
2964                 if (total_devs > 1) {
2965                         if (dev_nr < total_devs - 1) {
2966                                 bio = bio_clone(first_bio, GFP_NOFS);
2967                                 BUG_ON(!bio);
2968                         } else {
2969                                 bio = first_bio;
2970                         }
2971                         bio->bi_private = multi;
2972                         bio->bi_end_io = end_bio_multi_stripe;
2973                 }
2974                 bio->bi_sector = multi->stripes[dev_nr].physical >> 9;
2975                 dev = multi->stripes[dev_nr].dev;
2976                 BUG_ON(rw == WRITE && !dev->writeable);
2977                 if (dev && dev->bdev) {
2978                         bio->bi_bdev = dev->bdev;
2979                         if (async_submit)
2980                                 schedule_bio(root, dev, rw, bio);
2981                         else
2982                                 submit_bio(rw, bio);
2983                 } else {
2984                         bio->bi_bdev = root->fs_info->fs_devices->latest_bdev;
2985                         bio->bi_sector = logical >> 9;
2986                         bio_endio(bio, -EIO);
2987                 }
2988                 dev_nr++;
2989         }
2990         if (total_devs == 1)
2991                 kfree(multi);
2992         return 0;
2993 }
2994
2995 struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid,
2996                                        u8 *uuid, u8 *fsid)
2997 {
2998         struct btrfs_device *device;
2999         struct btrfs_fs_devices *cur_devices;
3000
3001         cur_devices = root->fs_info->fs_devices;
3002         while (cur_devices) {
3003                 if (!fsid ||
3004                     !memcmp(cur_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
3005                         device = __find_device(&cur_devices->devices,
3006                                                devid, uuid);
3007                         if (device)
3008                                 return device;
3009                 }
3010                 cur_devices = cur_devices->seed;
3011         }
3012         return NULL;
3013 }
3014
3015 static struct btrfs_device *add_missing_dev(struct btrfs_root *root,
3016                                             u64 devid, u8 *dev_uuid)
3017 {
3018         struct btrfs_device *device;
3019         struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
3020
3021         device = kzalloc(sizeof(*device), GFP_NOFS);
3022         if (!device)
3023                 return NULL;
3024         list_add(&device->dev_list,
3025                  &fs_devices->devices);
3026         device->barriers = 1;
3027         device->dev_root = root->fs_info->dev_root;
3028         device->devid = devid;
3029         device->work.func = pending_bios_fn;
3030         device->fs_devices = fs_devices;
3031         fs_devices->num_devices++;
3032         spin_lock_init(&device->io_lock);
3033         INIT_LIST_HEAD(&device->dev_alloc_list);
3034         memcpy(device->uuid, dev_uuid, BTRFS_UUID_SIZE);
3035         return device;
3036 }
3037
3038 static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
3039                           struct extent_buffer *leaf,
3040                           struct btrfs_chunk *chunk)
3041 {
3042         struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
3043         struct map_lookup *map;
3044         struct extent_map *em;
3045         u64 logical;
3046         u64 length;
3047         u64 devid;
3048         u8 uuid[BTRFS_UUID_SIZE];
3049         int num_stripes;
3050         int ret;
3051         int i;
3052
3053         logical = key->offset;
3054         length = btrfs_chunk_length(leaf, chunk);
3055
3056         spin_lock(&map_tree->map_tree.lock);
3057         em = lookup_extent_mapping(&map_tree->map_tree, logical, 1);
3058         spin_unlock(&map_tree->map_tree.lock);
3059
3060         /* already mapped? */
3061         if (em && em->start <= logical && em->start + em->len > logical) {
3062                 free_extent_map(em);
3063                 return 0;
3064         } else if (em) {
3065                 free_extent_map(em);
3066         }
3067
3068         em = alloc_extent_map(GFP_NOFS);
3069         if (!em)
3070                 return -ENOMEM;
3071         num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
3072         map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
3073         if (!map) {
3074                 free_extent_map(em);
3075                 return -ENOMEM;
3076         }
3077
3078         em->bdev = (struct block_device *)map;
3079         em->start = logical;
3080         em->len = length;
3081         em->block_start = 0;
3082         em->block_len = em->len;
3083
3084         map->num_stripes = num_stripes;
3085         map->io_width = btrfs_chunk_io_width(leaf, chunk);
3086         map->io_align = btrfs_chunk_io_align(leaf, chunk);
3087         map->sector_size = btrfs_chunk_sector_size(leaf, chunk);
3088         map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
3089         map->type = btrfs_chunk_type(leaf, chunk);
3090         map->sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);
3091         for (i = 0; i < num_stripes; i++) {
3092                 map->stripes[i].physical =
3093                         btrfs_stripe_offset_nr(leaf, chunk, i);
3094                 devid = btrfs_stripe_devid_nr(leaf, chunk, i);
3095                 read_extent_buffer(leaf, uuid, (unsigned long)
3096                                    btrfs_stripe_dev_uuid_nr(chunk, i),
3097                                    BTRFS_UUID_SIZE);
3098                 map->stripes[i].dev = btrfs_find_device(root, devid, uuid,
3099                                                         NULL);
3100                 if (!map->stripes[i].dev && !btrfs_test_opt(root, DEGRADED)) {
3101                         kfree(map);
3102                         free_extent_map(em);
3103                         return -EIO;
3104                 }
3105                 if (!map->stripes[i].dev) {
3106                         map->stripes[i].dev =
3107                                 add_missing_dev(root, devid, uuid);
3108                         if (!map->stripes[i].dev) {
3109                                 kfree(map);
3110                                 free_extent_map(em);
3111                                 return -EIO;
3112                         }
3113                 }
3114                 map->stripes[i].dev->in_fs_metadata = 1;
3115         }
3116
3117         spin_lock(&map_tree->map_tree.lock);
3118         ret = add_extent_mapping(&map_tree->map_tree, em);
3119         spin_unlock(&map_tree->map_tree.lock);
3120         BUG_ON(ret);
3121         free_extent_map(em);
3122
3123         return 0;
3124 }
3125
3126 static int fill_device_from_item(struct extent_buffer *leaf,
3127                                  struct btrfs_dev_item *dev_item,
3128                                  struct btrfs_device *device)
3129 {
3130         unsigned long ptr;
3131
3132         device->devid = btrfs_device_id(leaf, dev_item);
3133         device->disk_total_bytes = btrfs_device_total_bytes(leaf, dev_item);
3134         device->total_bytes = device->disk_total_bytes;
3135         device->bytes_used = btrfs_device_bytes_used(leaf, dev_item);
3136         device->type = btrfs_device_type(leaf, dev_item);
3137         device->io_align = btrfs_device_io_align(leaf, dev_item);
3138         device->io_width = btrfs_device_io_width(leaf, dev_item);
3139         device->sector_size = btrfs_device_sector_size(leaf, dev_item);
3140
3141         ptr = (unsigned long)btrfs_device_uuid(dev_item);
3142         read_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
3143
3144         return 0;
3145 }
3146
3147 static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
3148 {
3149         struct btrfs_fs_devices *fs_devices;
3150         int ret;
3151
3152         mutex_lock(&uuid_mutex);
3153
3154         fs_devices = root->fs_info->fs_devices->seed;
3155         while (fs_devices) {
3156                 if (!memcmp(fs_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
3157                         ret = 0;
3158                         goto out;
3159                 }
3160                 fs_devices = fs_devices->seed;
3161         }
3162
3163         fs_devices = find_fsid(fsid);
3164         if (!fs_devices) {
3165                 ret = -ENOENT;
3166                 goto out;
3167         }
3168
3169         fs_devices = clone_fs_devices(fs_devices);
3170         if (IS_ERR(fs_devices)) {
3171                 ret = PTR_ERR(fs_devices);
3172                 goto out;
3173         }
3174
3175         ret = __btrfs_open_devices(fs_devices, FMODE_READ,
3176                                    root->fs_info->bdev_holder);
3177         if (ret)
3178                 goto out;
3179
3180         if (!fs_devices->seeding) {
3181                 __btrfs_close_devices(fs_devices);
3182                 free_fs_devices(fs_devices);
3183                 ret = -EINVAL;
3184                 goto out;
3185         }
3186
3187         fs_devices->seed = root->fs_info->fs_devices->seed;
3188         root->fs_info->fs_devices->seed = fs_devices;
3189 out:
3190         mutex_unlock(&uuid_mutex);
3191         return ret;
3192 }
3193
3194 static int read_one_dev(struct btrfs_root *root,
3195                         struct extent_buffer *leaf,
3196                         struct btrfs_dev_item *dev_item)
3197 {
3198         struct btrfs_device *device;
3199         u64 devid;
3200         int ret;
3201         u8 fs_uuid[BTRFS_UUID_SIZE];
3202         u8 dev_uuid[BTRFS_UUID_SIZE];
3203
3204         devid = btrfs_device_id(leaf, dev_item);
3205         read_extent_buffer(leaf, dev_uuid,
3206                            (unsigned long)btrfs_device_uuid(dev_item),
3207                            BTRFS_UUID_SIZE);
3208         read_extent_buffer(leaf, fs_uuid,
3209                            (unsigned long)btrfs_device_fsid(dev_item),
3210                            BTRFS_UUID_SIZE);
3211
3212         if (memcmp(fs_uuid, root->fs_info->fsid, BTRFS_UUID_SIZE)) {
3213                 ret = open_seed_devices(root, fs_uuid);
3214                 if (ret && !btrfs_test_opt(root, DEGRADED))
3215                         return ret;
3216         }
3217
3218         device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
3219         if (!device || !device->bdev) {
3220                 if (!btrfs_test_opt(root, DEGRADED))
3221                         return -EIO;
3222
3223                 if (!device) {
3224                         printk(KERN_WARNING "warning devid %llu missing\n",
3225                                (unsigned long long)devid);
3226                         device = add_missing_dev(root, devid, dev_uuid);
3227                         if (!device)
3228                                 return -ENOMEM;
3229                 }
3230         }
3231
3232         if (device->fs_devices != root->fs_info->fs_devices) {
3233                 BUG_ON(device->writeable);
3234                 if (device->generation !=
3235                     btrfs_device_generation(leaf, dev_item))
3236                         return -EINVAL;
3237         }
3238
3239         fill_device_from_item(leaf, dev_item, device);
3240         device->dev_root = root->fs_info->dev_root;
3241         device->in_fs_metadata = 1;
3242         if (device->writeable)
3243                 device->fs_devices->total_rw_bytes += device->total_bytes;
3244         ret = 0;
3245         return ret;
3246 }
3247
3248 int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf)
3249 {
3250         struct btrfs_dev_item *dev_item;
3251
3252         dev_item = (struct btrfs_dev_item *)offsetof(struct btrfs_super_block,
3253                                                      dev_item);
3254         return read_one_dev(root, buf, dev_item);
3255 }
3256
3257 int btrfs_read_sys_array(struct btrfs_root *root)
3258 {
3259         struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
3260         struct extent_buffer *sb;
3261         struct btrfs_disk_key *disk_key;
3262         struct btrfs_chunk *chunk;
3263         u8 *ptr;
3264         unsigned long sb_ptr;
3265         int ret = 0;
3266         u32 num_stripes;
3267         u32 array_size;
3268         u32 len = 0;
3269         u32 cur;
3270         struct btrfs_key key;
3271
3272         sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
3273                                           BTRFS_SUPER_INFO_SIZE);
3274         if (!sb)
3275                 return -ENOMEM;
3276         btrfs_set_buffer_uptodate(sb);
3277         btrfs_set_buffer_lockdep_class(sb, 0);
3278
3279         write_extent_buffer(sb, super_copy, 0, BTRFS_SUPER_INFO_SIZE);
3280         array_size = btrfs_super_sys_array_size(super_copy);
3281
3282         ptr = super_copy->sys_chunk_array;
3283         sb_ptr = offsetof(struct btrfs_super_block, sys_chunk_array);
3284         cur = 0;
3285
3286         while (cur < array_size) {
3287                 disk_key = (struct btrfs_disk_key *)ptr;
3288                 btrfs_disk_key_to_cpu(&key, disk_key);
3289
3290                 len = sizeof(*disk_key); ptr += len;
3291                 sb_ptr += len;
3292                 cur += len;
3293
3294                 if (key.type == BTRFS_CHUNK_ITEM_KEY) {
3295                         chunk = (struct btrfs_chunk *)sb_ptr;
3296                         ret = read_one_chunk(root, &key, sb, chunk);
3297                         if (ret)
3298                                 break;
3299                         num_stripes = btrfs_chunk_num_stripes(sb, chunk);
3300                         len = btrfs_chunk_item_size(num_stripes);
3301                 } else {
3302                         ret = -EIO;
3303                         break;
3304                 }
3305                 ptr += len;
3306                 sb_ptr += len;
3307                 cur += len;
3308         }
3309         free_extent_buffer(sb);
3310         return ret;
3311 }
3312
3313 int btrfs_read_chunk_tree(struct btrfs_root *root)
3314 {
3315         struct btrfs_path *path;
3316         struct extent_buffer *leaf;
3317         struct btrfs_key key;
3318         struct btrfs_key found_key;
3319         int ret;
3320         int slot;
3321
3322         root = root->fs_info->chunk_root;
3323
3324         path = btrfs_alloc_path();
3325         if (!path)
3326                 return -ENOMEM;
3327
3328         /* first we search for all of the device items, and then we
3329          * read in all of the chunk items.  This way we can create chunk
3330          * mappings that reference all of the devices that are afound
3331          */
3332         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
3333         key.offset = 0;
3334         key.type = 0;
3335 again:
3336         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3337         while (1) {
3338                 leaf = path->nodes[0];
3339                 slot = path->slots[0];
3340                 if (slot >= btrfs_header_nritems(leaf)) {
3341                         ret = btrfs_next_leaf(root, path);
3342                         if (ret == 0)
3343                                 continue;
3344                         if (ret < 0)
3345                                 goto error;
3346                         break;
3347                 }
3348                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
3349                 if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
3350                         if (found_key.objectid != BTRFS_DEV_ITEMS_OBJECTID)
3351                                 break;
3352                         if (found_key.type == BTRFS_DEV_ITEM_KEY) {
3353                                 struct btrfs_dev_item *dev_item;
3354                                 dev_item = btrfs_item_ptr(leaf, slot,
3355                                                   struct btrfs_dev_item);
3356                                 ret = read_one_dev(root, leaf, dev_item);
3357                                 if (ret)
3358                                         goto error;
3359                         }
3360                 } else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
3361                         struct btrfs_chunk *chunk;
3362                         chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
3363                         ret = read_one_chunk(root, &found_key, leaf, chunk);
3364                         if (ret)
3365                                 goto error;
3366                 }
3367                 path->slots[0]++;
3368         }
3369         if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
3370                 key.objectid = 0;
3371                 btrfs_release_path(root, path);
3372                 goto again;
3373         }
3374         ret = 0;
3375 error:
3376         btrfs_free_path(path);
3377         return ret;
3378 }