2 * Copyright (C) 2007 Oracle. All rights reserved.
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.
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.
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.
18 #define _XOPEN_SOURCE 600
22 #include <sys/types.h>
24 #include <uuid/uuid.h>
29 #include "transaction.h"
30 #include "print-tree.h"
34 struct btrfs_device *dev;
39 struct cache_extent ce;
46 struct stripe stripes[];
49 #define map_lookup_size(n) (sizeof(struct map_lookup) + \
50 (sizeof(struct stripe) * (n)))
52 static LIST_HEAD(fs_uuids);
54 static struct btrfs_device *__find_device(struct list_head *head, u64 devid)
56 struct btrfs_device *dev;
57 struct list_head *cur;
59 list_for_each(cur, head) {
60 dev = list_entry(cur, struct btrfs_device, dev_list);
61 if (dev->devid == devid)
67 static struct btrfs_fs_devices *find_fsid(u8 *fsid)
69 struct list_head *cur;
70 struct btrfs_fs_devices *fs_devices;
72 list_for_each(cur, &fs_uuids) {
73 fs_devices = list_entry(cur, struct btrfs_fs_devices, list);
74 if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
80 static int device_list_add(const char *path,
81 struct btrfs_super_block *disk_super,
82 u64 devid, struct btrfs_fs_devices **fs_devices_ret)
84 struct btrfs_device *device;
85 struct btrfs_fs_devices *fs_devices;
86 u64 found_transid = btrfs_super_generation(disk_super);
88 fs_devices = find_fsid(disk_super->fsid);
90 fs_devices = kmalloc(sizeof(*fs_devices), GFP_NOFS);
93 INIT_LIST_HEAD(&fs_devices->devices);
94 list_add(&fs_devices->list, &fs_uuids);
95 memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
96 fs_devices->latest_devid = devid;
97 fs_devices->latest_trans = found_transid;
98 fs_devices->lowest_devid = (u64)-1;
101 device = __find_device(&fs_devices->devices, devid);
104 device = kzalloc(sizeof(*device), GFP_NOFS);
106 /* we can safely leave the fs_devices entry around */
109 device->devid = devid;
110 device->name = kstrdup(path, GFP_NOFS);
115 list_add(&device->dev_list, &fs_devices->devices);
118 if (found_transid > fs_devices->latest_trans) {
119 fs_devices->latest_devid = devid;
120 fs_devices->latest_trans = found_transid;
122 if (fs_devices->lowest_devid > devid) {
123 fs_devices->lowest_devid = devid;
124 printk("lowest devid now %llu\n", (unsigned long long)devid);
126 *fs_devices_ret = fs_devices;
130 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
132 struct list_head *head = &fs_devices->devices;
133 struct list_head *cur;
134 struct btrfs_device *device;
136 list_for_each(cur, head) {
137 device = list_entry(cur, struct btrfs_device, dev_list);
143 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags)
146 struct list_head *head = &fs_devices->devices;
147 struct list_head *cur;
148 struct btrfs_device *device;
151 list_for_each(cur, head) {
152 device = list_entry(cur, struct btrfs_device, dev_list);
153 fd = open(device->name, flags);
154 printk("opening %s devid %llu fd %d\n", device->name,
155 (unsigned long long)device->devid, fd);
160 if (device->devid == fs_devices->latest_devid)
161 fs_devices->latest_bdev = fd;
162 if (device->devid == fs_devices->lowest_devid)
163 fs_devices->lowest_bdev = fd;
168 btrfs_close_devices(fs_devices);
172 int btrfs_scan_one_device(int fd, const char *path,
173 struct btrfs_fs_devices **fs_devices_ret,
174 u64 *total_devs, u64 super_offset)
176 struct btrfs_super_block *disk_super;
186 ret = pread(fd, buf, 4096, super_offset);
191 disk_super = (struct btrfs_super_block *)buf;
192 if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
193 sizeof(disk_super->magic))) {
197 devid = le64_to_cpu(disk_super->dev_item.devid);
198 *total_devs = btrfs_super_num_devices(disk_super);
199 printk("found device %llu on %s\n", (unsigned long long)devid, path);
200 ret = device_list_add(path, disk_super, devid, fs_devices_ret);
209 * this uses a pretty simple search, the expectation is that it is
210 * called very infrequently and that a given device has a small number
213 static int find_free_dev_extent(struct btrfs_trans_handle *trans,
214 struct btrfs_device *device,
215 struct btrfs_path *path,
216 u64 num_bytes, u64 *start)
218 struct btrfs_key key;
219 struct btrfs_root *root = device->dev_root;
220 struct btrfs_dev_extent *dev_extent = NULL;
223 u64 search_start = 0;
224 u64 search_end = device->total_bytes;
228 struct extent_buffer *l;
233 /* FIXME use last free of some kind */
235 key.objectid = device->devid;
236 key.offset = search_start;
237 key.type = BTRFS_DEV_EXTENT_KEY;
238 ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
241 ret = btrfs_previous_item(root, path, 0, key.type);
245 btrfs_item_key_to_cpu(l, &key, path->slots[0]);
248 slot = path->slots[0];
249 if (slot >= btrfs_header_nritems(l)) {
250 ret = btrfs_next_leaf(root, path);
257 if (search_start >= search_end) {
261 *start = search_start;
265 *start = last_byte > search_start ?
266 last_byte : search_start;
267 if (search_end <= *start) {
273 btrfs_item_key_to_cpu(l, &key, slot);
275 if (key.objectid < device->devid)
278 if (key.objectid > device->devid)
281 if (key.offset >= search_start && key.offset > last_byte &&
283 if (last_byte < search_start)
284 last_byte = search_start;
285 hole_size = key.offset - last_byte;
286 if (key.offset > last_byte &&
287 hole_size >= num_bytes) {
292 if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY) {
297 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
298 last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent);
304 /* we have to make sure we didn't find an extent that has already
305 * been allocated by the map tree or the original allocation
307 btrfs_release_path(root, path);
308 BUG_ON(*start < search_start);
310 if (*start + num_bytes > search_end) {
314 /* check for pending inserts here */
318 btrfs_release_path(root, path);
322 int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
323 struct btrfs_device *device,
324 u64 owner, u64 num_bytes, u64 *start)
327 struct btrfs_path *path;
328 struct btrfs_root *root = device->dev_root;
329 struct btrfs_dev_extent *extent;
330 struct extent_buffer *leaf;
331 struct btrfs_key key;
333 path = btrfs_alloc_path();
337 ret = find_free_dev_extent(trans, device, path, num_bytes, start);
342 key.objectid = device->devid;
344 key.type = BTRFS_DEV_EXTENT_KEY;
345 ret = btrfs_insert_empty_item(trans, root, path, &key,
349 leaf = path->nodes[0];
350 extent = btrfs_item_ptr(leaf, path->slots[0],
351 struct btrfs_dev_extent);
352 btrfs_set_dev_extent_owner(leaf, extent, owner);
353 btrfs_set_dev_extent_length(leaf, extent, num_bytes);
354 btrfs_mark_buffer_dirty(leaf);
356 btrfs_free_path(path);
360 static int find_next_chunk(struct btrfs_root *root, u64 *objectid)
362 struct btrfs_path *path;
364 struct btrfs_key key;
365 struct btrfs_key found_key;
367 path = btrfs_alloc_path();
370 key.objectid = (u64)-1;
371 key.offset = (u64)-1;
372 key.type = BTRFS_CHUNK_ITEM_KEY;
374 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
380 ret = btrfs_previous_item(root, path, 0, BTRFS_CHUNK_ITEM_KEY);
384 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
386 *objectid = found_key.objectid + found_key.offset;
390 btrfs_free_path(path);
394 static int find_next_devid(struct btrfs_root *root, struct btrfs_path *path,
398 struct btrfs_key key;
399 struct btrfs_key found_key;
401 key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
402 key.type = BTRFS_DEV_ITEM_KEY;
403 key.offset = (u64)-1;
405 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
411 ret = btrfs_previous_item(root, path, BTRFS_DEV_ITEMS_OBJECTID,
416 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
418 *objectid = found_key.offset + 1;
422 btrfs_release_path(root, path);
427 * the device information is stored in the chunk root
428 * the btrfs_device struct should be fully filled in
430 int btrfs_add_device(struct btrfs_trans_handle *trans,
431 struct btrfs_root *root,
432 struct btrfs_device *device)
435 struct btrfs_path *path;
436 struct btrfs_dev_item *dev_item;
437 struct extent_buffer *leaf;
438 struct btrfs_key key;
442 root = root->fs_info->chunk_root;
444 path = btrfs_alloc_path();
448 ret = find_next_devid(root, path, &free_devid);
452 key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
453 key.type = BTRFS_DEV_ITEM_KEY;
454 key.offset = free_devid;
456 ret = btrfs_insert_empty_item(trans, root, path, &key,
461 leaf = path->nodes[0];
462 dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
464 device->devid = free_devid;
465 btrfs_set_device_id(leaf, dev_item, device->devid);
466 btrfs_set_device_type(leaf, dev_item, device->type);
467 btrfs_set_device_io_align(leaf, dev_item, device->io_align);
468 btrfs_set_device_io_width(leaf, dev_item, device->io_width);
469 btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
470 btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
471 btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
473 ptr = (unsigned long)btrfs_device_uuid(dev_item);
474 write_extent_buffer(leaf, device->uuid, ptr, BTRFS_DEV_UUID_SIZE);
475 btrfs_mark_buffer_dirty(leaf);
479 btrfs_free_path(path);
483 int btrfs_update_device(struct btrfs_trans_handle *trans,
484 struct btrfs_device *device)
487 struct btrfs_path *path;
488 struct btrfs_root *root;
489 struct btrfs_dev_item *dev_item;
490 struct extent_buffer *leaf;
491 struct btrfs_key key;
493 root = device->dev_root->fs_info->chunk_root;
495 path = btrfs_alloc_path();
499 key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
500 key.type = BTRFS_DEV_ITEM_KEY;
501 key.offset = device->devid;
503 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
512 leaf = path->nodes[0];
513 dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
515 btrfs_set_device_id(leaf, dev_item, device->devid);
516 btrfs_set_device_type(leaf, dev_item, device->type);
517 btrfs_set_device_io_align(leaf, dev_item, device->io_align);
518 btrfs_set_device_io_width(leaf, dev_item, device->io_width);
519 btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
520 btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
521 btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
522 btrfs_mark_buffer_dirty(leaf);
525 btrfs_free_path(path);
529 int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
530 struct btrfs_root *root,
531 struct btrfs_key *key,
532 struct btrfs_chunk *chunk, int item_size)
534 struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
535 struct btrfs_disk_key disk_key;
539 array_size = btrfs_super_sys_array_size(super_copy);
540 if (array_size + item_size > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE)
543 ptr = super_copy->sys_chunk_array + array_size;
544 btrfs_cpu_key_to_disk(&disk_key, key);
545 memcpy(ptr, &disk_key, sizeof(disk_key));
546 ptr += sizeof(disk_key);
547 memcpy(ptr, chunk, item_size);
548 item_size += sizeof(disk_key);
549 btrfs_set_super_sys_array_size(super_copy, array_size + item_size);
553 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
554 struct btrfs_root *extent_root, u64 *start,
555 u64 *num_bytes, u64 type)
558 struct btrfs_fs_info *info = extent_root->fs_info;
559 struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
560 struct btrfs_stripe *stripes;
561 struct btrfs_device *device = NULL;
562 struct btrfs_chunk *chunk;
563 struct list_head private_devs;
564 struct list_head *dev_list = &extent_root->fs_info->fs_devices->devices;
565 struct list_head *cur;
566 struct map_lookup *map;
568 u64 calc_size = 8 * 1024 * 1024;
575 int stripe_len = 64 * 1024;
576 struct btrfs_key key;
578 if (list_empty(dev_list))
581 if (type & BTRFS_BLOCK_GROUP_RAID0)
582 num_stripes = btrfs_super_num_devices(&info->super_copy);
583 if (type & BTRFS_BLOCK_GROUP_DATA)
584 stripe_len = 64 * 1024;
585 if (type & (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_SYSTEM))
586 stripe_len = 32 * 1024;
588 INIT_LIST_HEAD(&private_devs);
589 cur = dev_list->next;
591 /* build a private list of devices we will allocate from */
592 while(index < num_stripes) {
593 device = list_entry(cur, struct btrfs_device, dev_list);
594 avail = device->total_bytes - device->bytes_used;
596 if (avail > max_avail)
598 if (avail >= calc_size) {
599 list_move_tail(&device->dev_list, &private_devs);
605 if (index < num_stripes) {
606 list_splice(&private_devs, dev_list);
607 if (!looped && max_avail > 0) {
609 calc_size = max_avail;
615 ret = find_next_chunk(chunk_root, &key.objectid);
619 chunk = kmalloc(btrfs_chunk_item_size(num_stripes), GFP_NOFS);
623 map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
629 stripes = &chunk->stripe;
631 *num_bytes = calc_size * num_stripes;
633 while(index < num_stripes) {
634 BUG_ON(list_empty(&private_devs));
635 cur = private_devs.next;
636 device = list_entry(cur, struct btrfs_device, dev_list);
637 list_move_tail(&device->dev_list, dev_list);
639 ret = btrfs_alloc_dev_extent(trans, device,
641 calc_size, &dev_offset);
643 printk("alloc chunk size %llu from dev %llu\n",
644 (unsigned long long)calc_size,
645 (unsigned long long)device->devid);
646 device->bytes_used += calc_size;
647 ret = btrfs_update_device(trans, device);
650 map->stripes[index].dev = device;
651 map->stripes[index].physical = dev_offset;
652 btrfs_set_stack_stripe_devid(stripes + index, device->devid);
653 btrfs_set_stack_stripe_offset(stripes + index, dev_offset);
654 physical = dev_offset;
657 BUG_ON(!list_empty(&private_devs));
659 /* key.objectid was set above */
660 key.offset = *num_bytes;
661 key.type = BTRFS_CHUNK_ITEM_KEY;
662 btrfs_set_stack_chunk_owner(chunk, extent_root->root_key.objectid);
663 btrfs_set_stack_chunk_stripe_len(chunk, stripe_len);
664 btrfs_set_stack_chunk_type(chunk, type);
665 btrfs_set_stack_chunk_num_stripes(chunk, num_stripes);
666 btrfs_set_stack_chunk_io_align(chunk, stripe_len);
667 btrfs_set_stack_chunk_io_width(chunk, stripe_len);
668 btrfs_set_stack_chunk_sector_size(chunk, extent_root->sectorsize);
669 map->sector_size = extent_root->sectorsize;
670 map->stripe_len = stripe_len;
671 map->io_align = stripe_len;
672 map->io_width = stripe_len;
674 map->num_stripes = num_stripes;
676 ret = btrfs_insert_item(trans, chunk_root, &key, chunk,
677 btrfs_chunk_item_size(num_stripes));
679 *start = key.objectid;
681 map->ce.start = key.objectid;
682 map->ce.size = key.offset;
684 ret = insert_existing_cache_extent(
685 &extent_root->fs_info->mapping_tree.cache_tree,
693 void btrfs_mapping_init(struct btrfs_mapping_tree *tree)
695 cache_tree_init(&tree->cache_tree);
698 int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
699 u64 logical, u64 *phys, u64 *length,
700 struct btrfs_device **dev)
702 struct cache_extent *ce;
703 struct map_lookup *map;
709 ce = find_first_cache_extent(&map_tree->cache_tree, logical);
711 BUG_ON(ce->start > logical || ce->start + ce->size < logical);
712 map = container_of(ce, struct map_lookup, ce);
713 offset = logical - ce->start;
717 * stripe_nr counts the total number of stripes we have to stride
718 * to get to this block
720 stripe_nr = stripe_nr / map->stripe_len;
722 stripe_offset = stripe_nr * map->stripe_len;
723 BUG_ON(offset < stripe_offset);
725 /* stripe_offset is the offset of this block in its stripe*/
726 stripe_offset = offset - stripe_offset;
729 * after this do_div call, stripe_nr is the number of stripes
730 * on this device we have to walk to find the data, and
731 * stripe_index is the number of our device in the stripe array
733 stripe_index = stripe_nr % map->num_stripes;
734 stripe_nr = stripe_nr / map->num_stripes;
736 BUG_ON(stripe_index >= map->num_stripes);
738 *phys = map->stripes[stripe_index].physical + stripe_offset +
739 stripe_nr * map->stripe_len;
741 if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
742 /* we limit the length of each bio to what fits in a stripe */
743 *length = min_t(u64, ce->size - offset,
744 map->stripe_len - stripe_offset);
746 *length = ce->size - offset;
748 *dev = map->stripes[stripe_index].dev;
752 struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid)
754 struct list_head *head = &root->fs_info->fs_devices->devices;
756 return __find_device(head, devid);
759 static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
760 struct extent_buffer *leaf,
761 struct btrfs_chunk *chunk)
763 struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
764 struct map_lookup *map;
765 struct cache_extent *ce;
773 logical = key->objectid;
774 length = key->offset;
775 ce = find_first_cache_extent(&map_tree->cache_tree, logical);
777 /* already mapped? */
778 if (ce && ce->start <= logical && ce->start + ce->size > logical) {
782 num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
783 map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
787 map->ce.start = logical;
788 map->ce.size = length;
790 map->num_stripes = num_stripes;
791 map->io_width = btrfs_chunk_io_width(leaf, chunk);
792 map->io_align = btrfs_chunk_io_align(leaf, chunk);
793 map->sector_size = btrfs_chunk_sector_size(leaf, chunk);
794 map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
795 map->type = btrfs_chunk_type(leaf, chunk);
796 for (i = 0; i < num_stripes; i++) {
797 map->stripes[i].physical =
798 btrfs_stripe_offset_nr(leaf, chunk, i);
799 devid = btrfs_stripe_devid_nr(leaf, chunk, i);
800 map->stripes[i].dev = btrfs_find_device(root, devid);
801 if (!map->stripes[i].dev) {
807 ret = insert_existing_cache_extent(&map_tree->cache_tree, &map->ce);
813 static int fill_device_from_item(struct extent_buffer *leaf,
814 struct btrfs_dev_item *dev_item,
815 struct btrfs_device *device)
819 device->devid = btrfs_device_id(leaf, dev_item);
820 device->total_bytes = btrfs_device_total_bytes(leaf, dev_item);
821 device->bytes_used = btrfs_device_bytes_used(leaf, dev_item);
822 device->type = btrfs_device_type(leaf, dev_item);
823 device->io_align = btrfs_device_io_align(leaf, dev_item);
824 device->io_width = btrfs_device_io_width(leaf, dev_item);
825 device->sector_size = btrfs_device_sector_size(leaf, dev_item);
827 ptr = (unsigned long)btrfs_device_uuid(dev_item);
828 read_extent_buffer(leaf, device->uuid, ptr, BTRFS_DEV_UUID_SIZE);
833 static int read_one_dev(struct btrfs_root *root,
834 struct extent_buffer *leaf,
835 struct btrfs_dev_item *dev_item)
837 struct btrfs_device *device;
841 devid = btrfs_device_id(leaf, dev_item);
842 device = btrfs_find_device(root, devid);
844 printk("warning devid %llu not found already\n",
845 (unsigned long long)devid);
846 device = kmalloc(sizeof(*device), GFP_NOFS);
849 list_add(&device->dev_list,
850 &root->fs_info->fs_devices->devices);
853 fill_device_from_item(leaf, dev_item, device);
854 device->dev_root = root->fs_info->dev_root;
858 int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf)
860 struct btrfs_dev_item *dev_item;
862 dev_item = (struct btrfs_dev_item *)offsetof(struct btrfs_super_block,
864 return read_one_dev(root, buf, dev_item);
867 int btrfs_read_sys_array(struct btrfs_root *root)
869 struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
870 struct extent_buffer *sb = root->fs_info->sb_buffer;
871 struct btrfs_disk_key *disk_key;
872 struct btrfs_chunk *chunk;
873 struct btrfs_key key;
878 unsigned long sb_ptr;
882 array_size = btrfs_super_sys_array_size(super_copy);
885 * we do this loop twice, once for the device items and
886 * once for all of the chunks. This way there are device
887 * structs filled in for every chunk
889 ptr = super_copy->sys_chunk_array;
890 sb_ptr = offsetof(struct btrfs_super_block, sys_chunk_array);
893 while (cur < array_size) {
894 disk_key = (struct btrfs_disk_key *)ptr;
895 btrfs_disk_key_to_cpu(&key, disk_key);
897 len = sizeof(*disk_key);
902 if (key.type == BTRFS_CHUNK_ITEM_KEY) {
903 chunk = (struct btrfs_chunk *)sb_ptr;
904 ret = read_one_chunk(root, &key, sb, chunk);
906 num_stripes = btrfs_chunk_num_stripes(sb, chunk);
907 len = btrfs_chunk_item_size(num_stripes);
918 int btrfs_read_chunk_tree(struct btrfs_root *root)
920 struct btrfs_path *path;
921 struct extent_buffer *leaf;
922 struct btrfs_key key;
923 struct btrfs_key found_key;
927 root = root->fs_info->chunk_root;
929 path = btrfs_alloc_path();
933 /* first we search for all of the device items, and then we
934 * read in all of the chunk items. This way we can create chunk
935 * mappings that reference all of the devices that are afound
937 key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
941 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
943 leaf = path->nodes[0];
944 slot = path->slots[0];
945 if (slot >= btrfs_header_nritems(leaf)) {
946 ret = btrfs_next_leaf(root, path);
953 btrfs_item_key_to_cpu(leaf, &found_key, slot);
954 if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
955 if (found_key.objectid != BTRFS_DEV_ITEMS_OBJECTID)
957 if (found_key.type == BTRFS_DEV_ITEM_KEY) {
958 struct btrfs_dev_item *dev_item;
959 dev_item = btrfs_item_ptr(leaf, slot,
960 struct btrfs_dev_item);
961 ret = read_one_dev(root, leaf, dev_item);
964 } else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
965 struct btrfs_chunk *chunk;
966 chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
967 ret = read_one_chunk(root, &found_key, leaf, chunk);
971 if (key.objectid == BTRFS_DEV_ITEMS_OBJECTID) {
973 btrfs_release_path(root, path);
977 btrfs_free_path(path);