1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * BTRFS filesystem implementation for U-Boot
4 *
5 * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
6 */
7
8 #include "btrfs.h"
9
read_root_item(struct btrfs_path * p,struct btrfs_root_item * item)10 static void read_root_item(struct btrfs_path *p, struct btrfs_root_item *item)
11 {
12 u32 len;
13 int reset = 0;
14
15 len = btrfs_path_item_size(p);
16 memcpy(item, btrfs_path_item_ptr(p, struct btrfs_root_item), len);
17 btrfs_root_item_to_cpu(item);
18
19 if (len < sizeof(*item))
20 reset = 1;
21 if (!reset && item->generation != item->generation_v2) {
22 if (item->generation_v2 != 0)
23 printf("%s: generation != generation_v2 in root item",
24 __func__);
25 reset = 1;
26 }
27 if (reset) {
28 memset(&item->generation_v2, 0,
29 sizeof(*item) - offsetof(struct btrfs_root_item,
30 generation_v2));
31 }
32 }
33
btrfs_find_root(u64 objectid,struct btrfs_root * root,struct btrfs_root_item * root_item)34 int btrfs_find_root(u64 objectid, struct btrfs_root *root,
35 struct btrfs_root_item *root_item)
36 {
37 struct btrfs_path path;
38 struct btrfs_root_item my_root_item;
39
40 if (!btrfs_search_tree_key_type(&btrfs_info.tree_root, objectid,
41 BTRFS_ROOT_ITEM_KEY, &path))
42 return -1;
43
44 if (!root_item)
45 root_item = &my_root_item;
46 read_root_item(&path, root_item);
47
48 if (root) {
49 root->objectid = objectid;
50 root->bytenr = root_item->bytenr;
51 root->root_dirid = root_item->root_dirid;
52 }
53
54 btrfs_free_path(&path);
55 return 0;
56 }
57
btrfs_lookup_root_ref(u64 subvolid,struct btrfs_root_ref * refp,char * name)58 u64 btrfs_lookup_root_ref(u64 subvolid, struct btrfs_root_ref *refp, char *name)
59 {
60 struct btrfs_path path;
61 struct btrfs_key *key;
62 struct btrfs_root_ref *ref;
63 u64 res = -1ULL;
64
65 key = btrfs_search_tree_key_type(&btrfs_info.tree_root, subvolid,
66 BTRFS_ROOT_BACKREF_KEY, &path);
67
68 if (!key)
69 return -1ULL;
70
71 ref = btrfs_path_item_ptr(&path, struct btrfs_root_ref);
72 btrfs_root_ref_to_cpu(ref);
73
74 if (refp)
75 *refp = *ref;
76
77 if (name) {
78 if (ref->name_len > BTRFS_VOL_NAME_MAX) {
79 printf("%s: volume name too long: %u\n", __func__,
80 ref->name_len);
81 goto out;
82 }
83
84 memcpy(name, ref + 1, ref->name_len);
85 }
86
87 res = key->offset;
88 out:
89 btrfs_free_path(&path);
90 return res;
91 }
92
93