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btrfs-list.c
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btrfs-list.c
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/*
* Copyright (C) 2010 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#define _GNU_SOURCE
#ifndef __CHECKER__
#include <sys/ioctl.h>
#include <sys/mount.h>
#include "ioctl.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <libgen.h>
#include "ctree.h"
#include "transaction.h"
#include "utils.h"
#include <uuid/uuid.h>
#include "btrfs-list.h"
#define BTRFS_LIST_NFILTERS_INCREASE (2 * BTRFS_LIST_FILTER_MAX)
#define BTRFS_LIST_NCOMPS_INCREASE (2 * BTRFS_LIST_COMP_MAX)
/* we store all the roots we find in an rbtree so that we can
* search for them later.
*/
struct root_lookup {
struct rb_root root;
};
/*
* one of these for each root we find.
*/
struct root_info {
struct rb_node rb_node;
struct rb_node sort_node;
/* this root's id */
u64 root_id;
/* equal the offset of the root's key */
u64 root_offset;
/* flags of the root */
u64 flags;
/* the id of the root that references this one */
u64 ref_tree;
/* the dir id we're in from ref_tree */
u64 dir_id;
u64 top_id;
/* generation when the root is created or last updated */
u64 gen;
/* creation generation of this root in sec*/
u64 ogen;
/* creation time of this root in sec*/
time_t otime;
u8 uuid[BTRFS_UUID_SIZE];
/* path from the subvol we live in to this root, including the
* root's name. This is null until we do the extra lookup ioctl.
*/
char *path;
/* the name of this root in the directory it lives in */
char *name;
char *full_path;
};
struct {
char *name;
char *column_name;
int need_print;
} btrfs_list_columns[] = {
{
.name = "ID",
.column_name = "ID",
.need_print = 1,
},
{
.name = "gen",
.column_name = "Gen",
.need_print = 1,
},
{
.name = "cgen",
.column_name = "CGen",
.need_print = 0,
},
{
.name = "parent",
.column_name = "Parent",
.need_print = 0,
},
{
.name = "top level",
.column_name = "Top Level",
.need_print = 1,
},
{
.name = "otime",
.column_name = "OTime",
.need_print = 0,
},
{
.name = "uuid",
.column_name = "UUID",
.need_print = 0,
},
{
.name = "path",
.column_name = "Path",
.need_print = 1,
},
{
.name = NULL,
.column_name = NULL,
.need_print = 0,
},
};
static btrfs_list_filter_func all_filter_funcs[];
static btrfs_list_comp_func all_comp_funcs[];
void btrfs_list_setup_print_column(enum btrfs_list_column_enum column)
{
int i;
BUG_ON(column < 0 || column > BTRFS_LIST_ALL);
if (column < BTRFS_LIST_ALL) {
btrfs_list_columns[column].need_print = 1;
return;
}
for (i = 0; i < BTRFS_LIST_ALL; i++)
btrfs_list_columns[i].need_print = 1;
}
static void root_lookup_init(struct root_lookup *tree)
{
tree->root.rb_node = NULL;
}
static int comp_entry_with_rootid(struct root_info *entry1,
struct root_info *entry2,
int is_descending)
{
int ret;
if (entry1->root_id > entry2->root_id)
ret = 1;
else if (entry1->root_id < entry2->root_id)
ret = -1;
else
ret = 0;
return is_descending ? -ret : ret;
}
static int comp_entry_with_gen(struct root_info *entry1,
struct root_info *entry2,
int is_descending)
{
int ret;
if (entry1->gen > entry2->gen)
ret = 1;
else if (entry1->gen < entry2->gen)
ret = -1;
else
ret = 0;
return is_descending ? -ret : ret;
}
static int comp_entry_with_ogen(struct root_info *entry1,
struct root_info *entry2,
int is_descending)
{
int ret;
if (entry1->ogen > entry2->ogen)
ret = 1;
else if (entry1->ogen < entry2->ogen)
ret = -1;
else
ret = 0;
return is_descending ? -ret : ret;
}
static int comp_entry_with_path(struct root_info *entry1,
struct root_info *entry2,
int is_descending)
{
int ret;
if (strcmp(entry1->full_path, entry2->full_path) > 0)
ret = 1;
else if (strcmp(entry1->full_path, entry2->full_path) < 0)
ret = -1;
else
ret = 0;
return is_descending ? -ret : ret;
}
static btrfs_list_comp_func all_comp_funcs[] = {
[BTRFS_LIST_COMP_ROOTID] = comp_entry_with_rootid,
[BTRFS_LIST_COMP_OGEN] = comp_entry_with_ogen,
[BTRFS_LIST_COMP_GEN] = comp_entry_with_gen,
[BTRFS_LIST_COMP_PATH] = comp_entry_with_path,
};
static char *all_sort_items[] = {
[BTRFS_LIST_COMP_ROOTID] = "rootid",
[BTRFS_LIST_COMP_OGEN] = "ogen",
[BTRFS_LIST_COMP_GEN] = "gen",
[BTRFS_LIST_COMP_PATH] = "path",
[BTRFS_LIST_COMP_MAX] = NULL,
};
static int btrfs_list_get_sort_item(char *sort_name)
{
int i;
for (i = 0; i < BTRFS_LIST_COMP_MAX; i++) {
if (strcmp(sort_name, all_sort_items[i]) == 0)
return i;
}
return -1;
}
struct btrfs_list_comparer_set *btrfs_list_alloc_comparer_set(void)
{
struct btrfs_list_comparer_set *set;
int size;
size = sizeof(struct btrfs_list_comparer_set) +
BTRFS_LIST_NCOMPS_INCREASE * sizeof(struct btrfs_list_comparer);
set = malloc(size);
if (!set) {
fprintf(stderr, "memory allocation failed\n");
exit(1);
}
memset(set, 0, size);
set->total = BTRFS_LIST_NCOMPS_INCREASE;
return set;
}
void btrfs_list_free_comparer_set(struct btrfs_list_comparer_set *comp_set)
{
free(comp_set);
}
int btrfs_list_setup_comparer(struct btrfs_list_comparer_set **comp_set,
enum btrfs_list_comp_enum comparer,
int is_descending)
{
struct btrfs_list_comparer_set *set = *comp_set;
int size;
BUG_ON(!set);
BUG_ON(comparer >= BTRFS_LIST_COMP_MAX);
BUG_ON(set->ncomps > set->total);
if (set->ncomps == set->total) {
size = set->total + BTRFS_LIST_NCOMPS_INCREASE;
size = sizeof(*set) + size * sizeof(struct btrfs_list_comparer);
set = realloc(set, size);
if (!set) {
fprintf(stderr, "memory allocation failed\n");
exit(1);
}
memset(&set->comps[set->total], 0,
BTRFS_LIST_NCOMPS_INCREASE *
sizeof(struct btrfs_list_comparer));
set->total += BTRFS_LIST_NCOMPS_INCREASE;
*comp_set = set;
}
BUG_ON(set->comps[set->ncomps].comp_func);
set->comps[set->ncomps].comp_func = all_comp_funcs[comparer];
set->comps[set->ncomps].is_descending = is_descending;
set->ncomps++;
return 0;
}
static int sort_comp(struct root_info *entry1, struct root_info *entry2,
struct btrfs_list_comparer_set *set)
{
int rootid_compared = 0;
int i, ret = 0;
if (!set || !set->ncomps)
goto comp_rootid;
for (i = 0; i < set->ncomps; i++) {
if (!set->comps[i].comp_func)
break;
ret = set->comps[i].comp_func(entry1, entry2,
set->comps[i].is_descending);
if (ret)
return ret;
if (set->comps[i].comp_func == comp_entry_with_rootid)
rootid_compared = 1;
}
if (!rootid_compared) {
comp_rootid:
ret = comp_entry_with_rootid(entry1, entry2, 0);
}
return ret;
}
static int sort_tree_insert(struct root_lookup *sort_tree,
struct root_info *ins,
struct btrfs_list_comparer_set *comp_set)
{
struct rb_node **p = &sort_tree->root.rb_node;
struct rb_node *parent = NULL;
struct root_info *curr;
int ret;
while (*p) {
parent = *p;
curr = rb_entry(parent, struct root_info, sort_node);
ret = sort_comp(ins, curr, comp_set);
if (ret < 0)
p = &(*p)->rb_left;
else if (ret > 0)
p = &(*p)->rb_right;
else
return -EEXIST;
}
rb_link_node(&ins->sort_node, parent, p);
rb_insert_color(&ins->sort_node, &sort_tree->root);
return 0;
}
/*
* insert a new root into the tree. returns the existing root entry
* if one is already there. Both root_id and ref_tree are used
* as the key
*/
static int root_tree_insert(struct root_lookup *root_tree,
struct root_info *ins)
{
struct rb_node **p = &root_tree->root.rb_node;
struct rb_node * parent = NULL;
struct root_info *curr;
int ret;
while(*p) {
parent = *p;
curr = rb_entry(parent, struct root_info, rb_node);
ret = comp_entry_with_rootid(ins, curr, 0);
if (ret < 0)
p = &(*p)->rb_left;
else if (ret > 0)
p = &(*p)->rb_right;
else
return -EEXIST;
}
rb_link_node(&ins->rb_node, parent, p);
rb_insert_color(&ins->rb_node, &root_tree->root);
return 0;
}
/*
* find a given root id in the tree. We return the smallest one,
* rb_next can be used to move forward looking for more if required
*/
static struct root_info *root_tree_search(struct root_lookup *root_tree,
u64 root_id)
{
struct rb_node *n = root_tree->root.rb_node;
struct root_info *entry;
struct root_info tmp;
int ret;
tmp.root_id = root_id;
while(n) {
entry = rb_entry(n, struct root_info, rb_node);
ret = comp_entry_with_rootid(&tmp, entry, 0);
if (ret < 0)
n = n->rb_left;
else if (ret > 0)
n = n->rb_right;
else
return entry;
}
return NULL;
}
static int update_root(struct root_lookup *root_lookup,
u64 root_id, u64 ref_tree, u64 root_offset, u64 flags,
u64 dir_id, char *name, int name_len, u64 ogen, u64 gen,
time_t ot, void *uuid)
{
struct root_info *ri;
ri = root_tree_search(root_lookup, root_id);
if (!ri || ri->root_id != root_id)
return -ENOENT;
if (name && name_len > 0) {
if (ri->name)
free(ri->name);
ri->name = malloc(name_len + 1);
if (!ri->name) {
fprintf(stderr, "memory allocation failed\n");
exit(1);
}
strncpy(ri->name, name, name_len);
ri->name[name_len] = 0;
}
if (ref_tree)
ri->ref_tree = ref_tree;
if (root_offset)
ri->root_offset = root_offset;
if (flags)
ri->flags = flags;
if (dir_id)
ri->dir_id = dir_id;
if (gen)
ri->gen = gen;
if (ogen)
ri->ogen = ogen;
if (!ri->ogen && root_offset)
ri->ogen = root_offset;
if (ot)
ri->otime = ot;
if (uuid)
memcpy(&ri->uuid, uuid, BTRFS_UUID_SIZE);
return 0;
}
/*
* add_root - update the existed root, or allocate a new root and insert it
* into the lookup tree.
* root_id: object id of the root
* ref_tree: object id of the referring root.
* root_offset: offset value of the root'key
* dir_id: inode id of the directory in ref_tree where this root can be found.
* name: the name of root_id in that directory
* name_len: the length of name
* ogen: the original generation of the root
* gen: the current generation of the root
* ot: the original time(create time) of the root
* uuid: uuid of the root
*/
static int add_root(struct root_lookup *root_lookup,
u64 root_id, u64 ref_tree, u64 root_offset, u64 flags,
u64 dir_id, char *name, int name_len, u64 ogen, u64 gen,
time_t ot, void *uuid)
{
struct root_info *ri;
int ret;
ret = update_root(root_lookup, root_id, ref_tree, root_offset, flags,
dir_id, name, name_len, ogen, gen, ot, uuid);
if (!ret)
return 0;
ri = malloc(sizeof(*ri));
if (!ri) {
printf("memory allocation failed\n");
exit(1);
}
memset(ri, 0, sizeof(*ri));
ri->root_id = root_id;
if (name && name_len > 0) {
ri->name = malloc(name_len + 1);
if (!ri->name) {
fprintf(stderr, "memory allocation failed\n");
exit(1);
}
strncpy(ri->name, name, name_len);
ri->name[name_len] = 0;
}
if (ref_tree)
ri->ref_tree = ref_tree;
if (dir_id)
ri->dir_id = dir_id;
if (root_offset)
ri->root_offset = root_offset;
if (flags)
ri->flags = flags;
if (gen)
ri->gen = gen;
if (ogen)
ri->ogen = ogen;
if (!ri->ogen && root_offset)
ri->ogen = root_offset;
if (ot)
ri->otime = ot;
if (uuid)
memcpy(&ri->uuid, uuid, BTRFS_UUID_SIZE);
ret = root_tree_insert(root_lookup, ri);
if (ret) {
printf("failed to insert tree %llu\n", (unsigned long long)root_id);
exit(1);
}
return 0;
}
void __free_root_info(struct root_info *ri)
{
if (ri->name)
free(ri->name);
if (ri->path)
free(ri->path);
if (ri->full_path)
free(ri->full_path);
free(ri);
}
void __free_all_subvolumn(struct root_lookup *root_tree)
{
struct root_info *entry;
struct rb_node *n;
n = rb_first(&root_tree->root);
while (n) {
entry = rb_entry(n, struct root_info, rb_node);
rb_erase(n, &root_tree->root);
__free_root_info(entry);
n = rb_first(&root_tree->root);
}
}
/*
* for a given root_info, search through the root_lookup tree to construct
* the full path name to it.
*
* This can't be called until all the root_info->path fields are filled
* in by lookup_ino_path
*/
static int resolve_root(struct root_lookup *rl, struct root_info *ri,
u64 top_id)
{
char *full_path = NULL;
int len = 0;
struct root_info *found;
/*
* we go backwards from the root_info object and add pathnames
* from parent directories as we go.
*/
found = ri;
while (1) {
char *tmp;
u64 next;
int add_len = strlen(found->path);
/* room for / and for null */
tmp = malloc(add_len + 2 + len);
if (!tmp) {
perror("malloc failed");
exit(1);
}
if (full_path) {
memcpy(tmp + add_len + 1, full_path, len);
tmp[add_len] = '/';
memcpy(tmp, found->path, add_len);
tmp [add_len + len + 1] = '\0';
free(full_path);
full_path = tmp;
len += add_len + 1;
} else {
full_path = strdup(found->path);
len = add_len;
}
next = found->ref_tree;
if (next == top_id) {
ri->top_id = top_id;
break;
}
if (next == BTRFS_FS_TREE_OBJECTID) {
char p[] = "<FS_TREE>";
add_len = strlen(p);
len = strlen(full_path);
tmp = malloc(len + add_len + 2);
memcpy(tmp + add_len + 1, full_path, len);
tmp[add_len] = '/';
memcpy(tmp, p, add_len);
free(full_path);
full_path = tmp;
ri->top_id = next;
break;
}
/*
* if the ref_tree wasn't in our tree of roots, we're
* at the top
*/
found = root_tree_search(rl, next);
if (!found) {
ri->top_id = next;
break;
}
}
ri->full_path = full_path;
return 0;
}
/*
* for a single root_info, ask the kernel to give us a path name
* inside it's ref_root for the dir_id where it lives.
*
* This fills in root_info->path with the path to the directory and and
* appends this root's name.
*/
static int lookup_ino_path(int fd, struct root_info *ri)
{
struct btrfs_ioctl_ino_lookup_args args;
int ret, e;
if (ri->path)
return 0;
memset(&args, 0, sizeof(args));
args.treeid = ri->ref_tree;
args.objectid = ri->dir_id;
ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
e = errno;
if (ret) {
fprintf(stderr, "ERROR: Failed to lookup path for root %llu - %s\n",
(unsigned long long)ri->ref_tree,
strerror(e));
return ret;
}
if (args.name[0]) {
/*
* we're in a subdirectory of ref_tree, the kernel ioctl
* puts a / in there for us
*/
ri->path = malloc(strlen(ri->name) + strlen(args.name) + 1);
if (!ri->path) {
perror("malloc failed");
exit(1);
}
strcpy(ri->path, args.name);
strcat(ri->path, ri->name);
} else {
/* we're at the root of ref_tree */
ri->path = strdup(ri->name);
if (!ri->path) {
perror("strdup failed");
exit(1);
}
}
return 0;
}
/* finding the generation for a given path is a two step process.
* First we use the inode loookup routine to find out the root id
*
* Then we use the tree search ioctl to scan all the root items for a
* given root id and spit out the latest generation we can find
*/
static u64 find_root_gen(int fd)
{
struct btrfs_ioctl_ino_lookup_args ino_args;
int ret;
struct btrfs_ioctl_search_args args;
struct btrfs_ioctl_search_key *sk = &args.key;
struct btrfs_ioctl_search_header sh;
unsigned long off = 0;
u64 max_found = 0;
int i;
int e;
memset(&ino_args, 0, sizeof(ino_args));
ino_args.objectid = BTRFS_FIRST_FREE_OBJECTID;
/* this ioctl fills in ino_args->treeid */
ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_args);
e = errno;
if (ret) {
fprintf(stderr, "ERROR: Failed to lookup path for dirid %llu - %s\n",
(unsigned long long)BTRFS_FIRST_FREE_OBJECTID,
strerror(e));
return 0;
}
memset(&args, 0, sizeof(args));
sk->tree_id = 1;
/*
* there may be more than one ROOT_ITEM key if there are
* snapshots pending deletion, we have to loop through
* them.
*/
sk->min_objectid = ino_args.treeid;
sk->max_objectid = ino_args.treeid;
sk->max_type = BTRFS_ROOT_ITEM_KEY;
sk->min_type = BTRFS_ROOT_ITEM_KEY;
sk->max_offset = (u64)-1;
sk->max_transid = (u64)-1;
sk->nr_items = 4096;
while (1) {
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
e = errno;
if (ret < 0) {
fprintf(stderr, "ERROR: can't perform the search - %s\n",
strerror(e));
return 0;
}
/* the ioctl returns the number of item it found in nr_items */
if (sk->nr_items == 0)
break;
off = 0;
for (i = 0; i < sk->nr_items; i++) {
struct btrfs_root_item *item;
memcpy(&sh, args.buf + off, sizeof(sh));
off += sizeof(sh);
item = (struct btrfs_root_item *)(args.buf + off);
off += sh.len;
sk->min_objectid = sh.objectid;
sk->min_type = sh.type;
sk->min_offset = sh.offset;
if (sh.objectid > ino_args.treeid)
break;
if (sh.objectid == ino_args.treeid &&
sh.type == BTRFS_ROOT_ITEM_KEY) {
max_found = max(max_found,
btrfs_root_generation(item));
}
}
if (sk->min_offset < (u64)-1)
sk->min_offset++;
else
break;
if (sk->min_type != BTRFS_ROOT_ITEM_KEY)
break;
if (sk->min_objectid != BTRFS_ROOT_ITEM_KEY)
break;
}
return max_found;
}
/* pass in a directory id and this will return
* the full path of the parent directory inside its
* subvolume root.
*
* It may return NULL if it is in the root, or an ERR_PTR if things
* go badly.
*/
static char *__ino_resolve(int fd, u64 dirid)
{
struct btrfs_ioctl_ino_lookup_args args;
int ret;
char *full;
int e;
memset(&args, 0, sizeof(args));
args.objectid = dirid;
ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
e = errno;
if (ret) {
fprintf(stderr, "ERROR: Failed to lookup path for dirid %llu - %s\n",
(unsigned long long)dirid, strerror(e) );
return ERR_PTR(ret);
}
if (args.name[0]) {
/*
* we're in a subdirectory of ref_tree, the kernel ioctl
* puts a / in there for us
*/
full = strdup(args.name);
if (!full) {
perror("malloc failed");
return ERR_PTR(-ENOMEM);
}
} else {
/* we're at the root of ref_tree */
full = NULL;
}
return full;
}
/*
* simple string builder, returning a new string with both
* dirid and name
*/
char *build_name(char *dirid, char *name)
{
char *full;
if (!dirid)
return strdup(name);
full = malloc(strlen(dirid) + strlen(name) + 1);
if (!full)
return NULL;
strcpy(full, dirid);
strcat(full, name);
return full;
}
/*
* given an inode number, this returns the full path name inside the subvolume
* to that file/directory. cache_dirid and cache_name are used to
* cache the results so we can avoid tree searches if a later call goes
* to the same directory or file name
*/
static char *ino_resolve(int fd, u64 ino, u64 *cache_dirid, char **cache_name)
{
u64 dirid;
char *dirname;
char *name;
char *full;
int ret;
struct btrfs_ioctl_search_args args;
struct btrfs_ioctl_search_key *sk = &args.key;
struct btrfs_ioctl_search_header *sh;
unsigned long off = 0;
int namelen;
int e;
memset(&args, 0, sizeof(args));
sk->tree_id = 0;
/*
* step one, we search for the inode back ref. We just use the first
* one
*/
sk->min_objectid = ino;
sk->max_objectid = ino;
sk->max_type = BTRFS_INODE_REF_KEY;
sk->max_offset = (u64)-1;
sk->min_type = BTRFS_INODE_REF_KEY;
sk->max_transid = (u64)-1;
sk->nr_items = 1;
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
e = errno;
if (ret < 0) {
fprintf(stderr, "ERROR: can't perform the search - %s\n",
strerror(e));
return NULL;
}
/* the ioctl returns the number of item it found in nr_items */
if (sk->nr_items == 0)
return NULL;
off = 0;
sh = (struct btrfs_ioctl_search_header *)(args.buf + off);
if (sh->type == BTRFS_INODE_REF_KEY) {
struct btrfs_inode_ref *ref;
dirid = sh->offset;
ref = (struct btrfs_inode_ref *)(sh + 1);
namelen = btrfs_stack_inode_ref_name_len(ref);
name = (char *)(ref + 1);
name = strndup(name, namelen);
/* use our cached value */
if (dirid == *cache_dirid && *cache_name) {
dirname = *cache_name;
goto build;
}
} else {
return NULL;
}
/*
* the inode backref gives us the file name and the parent directory id.
* From here we use __ino_resolve to get the path to the parent
*/
dirname = __ino_resolve(fd, dirid);
build:
full = build_name(dirname, name);
if (*cache_name && dirname != *cache_name)
free(*cache_name);
*cache_name = dirname;
*cache_dirid = dirid;
free(name);
return full;
}
int btrfs_list_get_default_subvolume(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);
}