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Btrfs-progs: bring 'subvol get-default' back in 

Commit bab2c565 accidentally broke 'subvol get-default' command by
removing almost all of the underlying code.  Bring it back with some
fixes and improvements.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
master
Ilya Dryomov 2012-03-12 19:17:39 +02:00
parent 55bf019ff4
commit a0bdde58f8
2 changed files with 82 additions and 1 deletions
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81
btrfs-list.c
View File

@ -552,6 +552,60 @@ build:
return full;
}
static int get_default_subvolid(int fd, u64 *default_id)
{
struct btrfs_ioctl_search_args args;
struct btrfs_ioctl_search_key *sk = &args.key;
struct btrfs_ioctl_search_header *sh;
u64 found = 0;
int ret;
memset(&args, 0, sizeof(args));
/*
* search for a dir item with a name 'default' in the tree of
* tree roots, it should point us to a default root
*/
sk->tree_id = 1;
/* don't worry about ancient format and request only one item */
sk->nr_items = 1;
sk->max_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
sk->min_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
sk->max_type = BTRFS_DIR_ITEM_KEY;
sk->min_type = BTRFS_DIR_ITEM_KEY;
sk->max_offset = (u64)-1;
sk->max_transid = (u64)-1;
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
if (ret < 0)
return ret;
/* the ioctl returns the number of items it found in nr_items */
if (sk->nr_items == 0)
goto out;
sh = (struct btrfs_ioctl_search_header *)args.buf;
if (sh->type == BTRFS_DIR_ITEM_KEY) {
struct btrfs_dir_item *di;
int name_len;
char *name;
di = (struct btrfs_dir_item *)(sh + 1);
name_len = btrfs_stack_dir_name_len(di);
name = (char *)(di + 1);
if (!strncmp("default", name, name_len))
found = btrfs_disk_key_objectid(&di->location);
}
out:
*default_id = found;
return 0;
}
static int __list_subvol_search(int fd, struct root_lookup *root_lookup)
{
int ret;
@ -663,12 +717,32 @@ static int __list_subvol_fill_paths(int fd, struct root_lookup *root_lookup)
return 0;
}
int list_subvols(int fd, int print_parent)
int list_subvols(int fd, int print_parent, int get_default)
{
struct root_lookup root_lookup;
struct rb_node *n;
u64 default_id;
int ret;
if (get_default) {
ret = get_default_subvolid(fd, &default_id);
if (ret) {
fprintf(stderr, "ERROR: can't perform the search - %s\n",
strerror(errno));
return ret;
}
if (default_id == 0) {
fprintf(stderr, "ERROR: 'default' dir item not found\n");
return ret;
}
/* no need to resolve roots if FS_TREE is default */
if (default_id == BTRFS_FS_TREE_OBJECTID) {
printf("ID 5 (FS_TREE)\n");
return ret;
}
}
ret = __list_subvol_search(fd, &root_lookup);
if (ret) {
fprintf(stderr, "ERROR: can't perform the search - %s\n",
@ -696,6 +770,11 @@ int list_subvols(int fd, int print_parent)
char *path;
entry = rb_entry(n, struct root_info, rb_node);
if (get_default && entry->root_id != default_id) {
n = rb_prev(n);
continue;
}
resolve_root(&root_lookup, entry, &parent_id, &level, &path);
if (print_parent) {
printf("ID %llu parent %llu top level %llu path %s\n",

2
ctree.h
View File

@ -1416,6 +1416,8 @@ BTRFS_SETGET_FUNCS(dir_type, struct btrfs_dir_item, type, 8);
BTRFS_SETGET_FUNCS(dir_name_len, struct btrfs_dir_item, name_len, 16);
BTRFS_SETGET_FUNCS(dir_transid, struct btrfs_dir_item, transid, 64);
BTRFS_SETGET_STACK_FUNCS(stack_dir_name_len, struct btrfs_dir_item, name_len, 16);
static inline void btrfs_dir_item_key(struct extent_buffer *eb,
struct btrfs_dir_item *item,
struct btrfs_disk_key *key)