subvolume.c
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/*
* BTRFS filesystem implementation for U-Boot
*
* 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include "btrfs.h"
#include <malloc.h>
static int get_subvol_name(u64 subvolid, char *name, int max_len)
{
struct btrfs_root_ref rref;
struct btrfs_inode_ref iref;
struct btrfs_root root;
u64 dir;
char tmp[max(BTRFS_VOL_NAME_MAX, BTRFS_NAME_MAX)];
char *ptr;
ptr = name + max_len - 1;
*ptr = '\0';
while (subvolid != BTRFS_FS_TREE_OBJECTID) {
subvolid = btrfs_lookup_root_ref(subvolid, &rref, tmp);
if (subvolid == -1ULL)
return -1;
ptr -= rref.name_len + 1;
if (ptr < name)
goto too_long;
memcpy(ptr + 1, tmp, rref.name_len);
*ptr = '/';
if (btrfs_find_root(subvolid, &root, NULL))
return -1;
dir = rref.dirid;
while (dir != BTRFS_FIRST_FREE_OBJECTID) {
dir = btrfs_lookup_inode_ref(&root, dir, &iref, tmp);
if (dir == -1ULL)
return -1;
ptr -= iref.name_len + 1;
if (ptr < name)
goto too_long;
memcpy(ptr + 1, tmp, iref.name_len);
*ptr = '/';
}
}
if (ptr == name + max_len - 1) {
name[0] = '/';
name[1] = '\0';
} else {
memmove(name, ptr, name + max_len - ptr);
}
return 0;
too_long:
printf("%s: subvolume name too long\n", __func__);
return -1;
}
u64 btrfs_get_default_subvol_objectid(void)
{
struct btrfs_dir_item item;
if (btrfs_lookup_dir_item(&btrfs_info.tree_root,
btrfs_info.sb.root_dir_objectid, "default", 7,
&item))
return BTRFS_FS_TREE_OBJECTID;
return item.location.objectid;
}
static void list_subvols(u64 tree, char *nameptr, int max_name_len, int level)
{
struct btrfs_key key, *found_key;
struct btrfs_path path;
struct btrfs_root_ref *ref;
int res;
key.objectid = tree;
key.type = BTRFS_ROOT_REF_KEY;
key.offset = 0;
if (btrfs_search_tree(&btrfs_info.tree_root, &key, &path))
return;
do {
found_key = btrfs_path_leaf_key(&path);
if (btrfs_comp_keys_type(&key, found_key))
break;
ref = btrfs_path_item_ptr(&path, struct btrfs_root_ref);
btrfs_root_ref_to_cpu(ref);
printf("ID %llu parent %llu name ", found_key->offset, tree);
if (nameptr && !get_subvol_name(found_key->offset, nameptr,
max_name_len))
printf("%s\n", nameptr);
else
printf("%.*s\n", (int) ref->name_len,
(const char *) (ref + 1));
if (level > 0)
list_subvols(found_key->offset, nameptr, max_name_len,
level - 1);
else
printf("%s: Too much recursion, maybe skipping some "
"subvolumes\n", __func__);
} while (!(res = btrfs_next_slot(&path)));
btrfs_free_path(&path);
}
void btrfs_list_subvols(void)
{
char *nameptr = malloc(4096);
list_subvols(BTRFS_FS_TREE_OBJECTID, nameptr, nameptr ? 4096 : 0, 40);
if (nameptr)
free(nameptr);
}