fs/btrfs/root.c

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