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btrfs-progs/libbtrfs/send-utils.c

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/*
* Copyright (C) 2012 Alexander Block. 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.
*/
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <uuid/uuid.h>
#include <limits.h>
#include <errno.h>
#include "kernel-shared/ctree.h"
#include "common/send-utils.h"
#include "common/messages.h"
#include "common/utils.h"
#include "ioctl.h"
#include "btrfs-list.h"
static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
u64 subvol_id);
static int btrfs_get_root_id_by_sub_path(int mnt_fd, const char *sub_path,
u64 *root_id)
{
int ret;
int subvol_fd;
subvol_fd = openat(mnt_fd, sub_path, O_RDONLY);
if (subvol_fd < 0) {
ret = -errno;
fprintf(stderr, "ERROR: open %s failed: %m\n", sub_path);
return ret;
}
ret = lookup_path_rootid(subvol_fd, root_id);
if (ret) {
errno = -ret;
error("cannot resolve rootid for path: %m");
}
close(subvol_fd);
return ret;
}
static int btrfs_read_root_item_raw(int mnt_fd, u64 root_id, size_t buf_len,
u32 *read_len, void *buf)
{
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 found = 0;
int i;
*read_len = 0;
memset(&args, 0, sizeof(args));
sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
/*
* there may be more than one ROOT_ITEM key if there are
* snapshots pending deletion, we have to loop through
* them.
*/
sk->min_objectid = root_id;
sk->max_objectid = root_id;
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(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
if (ret < 0) {
fprintf(stderr,
"ERROR: can't perform the search - %m\n");
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;
sh = (struct btrfs_ioctl_search_header *)(args.buf +
off);
off += sizeof(*sh);
item = (struct btrfs_root_item *)(args.buf + off);
off += btrfs_search_header_len(sh);
sk->min_objectid = btrfs_search_header_objectid(sh);
sk->min_type = btrfs_search_header_type(sh);
sk->min_offset = btrfs_search_header_offset(sh);
if (btrfs_search_header_objectid(sh) > root_id)
break;
if (btrfs_search_header_objectid(sh) == root_id &&
btrfs_search_header_type(sh) == BTRFS_ROOT_ITEM_KEY) {
if (btrfs_search_header_len(sh) > buf_len) {
/* btrfs-progs is too old for kernel */
fprintf(stderr,
"ERROR: buf for read_root_item_raw() is too small, get newer btrfs tools!\n");
return -EOVERFLOW;
}
memcpy(buf, item, btrfs_search_header_len(sh));
*read_len = btrfs_search_header_len(sh);
found = 1;
}
}
if (sk->min_offset < (u64)-1)
sk->min_offset++;
else
break;
if (sk->min_type != BTRFS_ROOT_ITEM_KEY ||
sk->min_objectid != root_id)
break;
}
return found ? 0 : -ENOENT;
}
/*
* Read a root item from the tree. In case we detect a root item smaller then
* sizeof(root_item), we know it's an old version of the root structure and
* initialize all new fields to zero. The same happens if we detect mismatching
* generation numbers as then we know the root was once mounted with an older
* kernel that was not aware of the root item structure change.
*/
static int btrfs_read_root_item(int mnt_fd, u64 root_id,
struct btrfs_root_item *item)
{
int ret;
u32 read_len;
ret = btrfs_read_root_item_raw(mnt_fd, root_id, sizeof(*item),
&read_len, item);
if (ret)
return ret;
if (read_len < sizeof(*item) ||
btrfs_root_generation(item) != btrfs_root_generation_v2(item)) {
/*
* Workaround for gcc9 that warns that memset over
* generation_v2 overflows, which is what we want but would
* be otherwise a bug
*
* The below is &item->generation_v2
*/
char *start = (char *)item + offsetof(struct btrfs_root_item,
generation_v2);
memset(start, 0,
sizeof(*item) - offsetof(struct btrfs_root_item,
generation_v2));
}
return 0;
}
#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
static struct rb_node *tree_insert(struct rb_root *root,
struct subvol_info *si,
enum subvol_search_type type)
{
struct rb_node **p = &root->rb_node;
struct rb_node *parent = NULL;
struct subvol_info *entry;
__s64 comp;
while (*p) {
parent = *p;
if (type == subvol_search_by_received_uuid) {
entry = rb_entry(parent, struct subvol_info,
rb_received_node);
comp = memcmp(entry->received_uuid, si->received_uuid,
BTRFS_UUID_SIZE);
if (!comp) {
if (entry->stransid < si->stransid)
comp = -1;
else if (entry->stransid > si->stransid)
comp = 1;
else
comp = 0;
}
} else if (type == subvol_search_by_uuid) {
entry = rb_entry(parent, struct subvol_info,
rb_local_node);
comp = memcmp(entry->uuid, si->uuid, BTRFS_UUID_SIZE);
} else if (type == subvol_search_by_root_id) {
entry = rb_entry(parent, struct subvol_info,
rb_root_id_node);
comp = entry->root_id - si->root_id;
} else if (type == subvol_search_by_path) {
entry = rb_entry(parent, struct subvol_info,
rb_path_node);
comp = strcmp(entry->path, si->path);
} else {
BUG();
}
if (comp < 0)
p = &(*p)->rb_left;
else if (comp > 0)
p = &(*p)->rb_right;
else
return parent;
}
if (type == subvol_search_by_received_uuid) {
rb_link_node(&si->rb_received_node, parent, p);
rb_insert_color(&si->rb_received_node, root);
} else if (type == subvol_search_by_uuid) {
rb_link_node(&si->rb_local_node, parent, p);
rb_insert_color(&si->rb_local_node, root);
} else if (type == subvol_search_by_root_id) {
rb_link_node(&si->rb_root_id_node, parent, p);
rb_insert_color(&si->rb_root_id_node, root);
} else if (type == subvol_search_by_path) {
rb_link_node(&si->rb_path_node, parent, p);
rb_insert_color(&si->rb_path_node, root);
}
return NULL;
}
#endif
int btrfs_subvolid_resolve(int fd, char *path, size_t path_len, u64 subvol_id)
{
if (path_len < 1)
return -EOVERFLOW;
path[0] = '\0';
path_len--;
path[path_len] = '\0';
return btrfs_subvolid_resolve_sub(fd, path, &path_len, subvol_id);
}
static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
u64 subvol_id)
{
int ret;
struct btrfs_ioctl_search_args search_arg;
struct btrfs_ioctl_ino_lookup_args ino_lookup_arg;
struct btrfs_ioctl_search_header *search_header;
struct btrfs_root_ref *backref_item;
if (subvol_id == BTRFS_FS_TREE_OBJECTID) {
if (*path_len < 1)
return -EOVERFLOW;
*path = '\0';
(*path_len)--;
return 0;
}
memset(&search_arg, 0, sizeof(search_arg));
search_arg.key.tree_id = BTRFS_ROOT_TREE_OBJECTID;
search_arg.key.min_objectid = subvol_id;
search_arg.key.max_objectid = subvol_id;
search_arg.key.min_type = BTRFS_ROOT_BACKREF_KEY;
search_arg.key.max_type = BTRFS_ROOT_BACKREF_KEY;
search_arg.key.max_offset = (u64)-1;
search_arg.key.max_transid = (u64)-1;
search_arg.key.nr_items = 1;
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_arg);
if (ret < 0) {
fprintf(stderr,
"ioctl(BTRFS_IOC_TREE_SEARCH, subvol_id %llu) ret=%d, error: %m\n",
(unsigned long long)subvol_id, ret);
return ret;
}
if (search_arg.key.nr_items < 1) {
fprintf(stderr,
"failed to lookup subvol_id %llu!\n",
(unsigned long long)subvol_id);
return -ENOENT;
}
search_header = (struct btrfs_ioctl_search_header *)search_arg.buf;
backref_item = (struct btrfs_root_ref *)(search_header + 1);
if (btrfs_search_header_offset(search_header)
!= BTRFS_FS_TREE_OBJECTID) {
int sub_ret;
sub_ret = btrfs_subvolid_resolve_sub(fd, path, path_len,
btrfs_search_header_offset(search_header));
if (sub_ret)
return sub_ret;
if (*path_len < 1)
return -EOVERFLOW;
strcat(path, "/");
(*path_len)--;
}
if (btrfs_stack_root_ref_dirid(backref_item) !=
BTRFS_FIRST_FREE_OBJECTID) {
int len;
memset(&ino_lookup_arg, 0, sizeof(ino_lookup_arg));
ino_lookup_arg.treeid =
btrfs_search_header_offset(search_header);
ino_lookup_arg.objectid =
btrfs_stack_root_ref_dirid(backref_item);
ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_lookup_arg);
if (ret < 0) {
fprintf(stderr,
"ioctl(BTRFS_IOC_INO_LOOKUP) ret=%d, error: %m\n",
ret);
return ret;
}
len = strlen(ino_lookup_arg.name);
if (*path_len < len)
return -EOVERFLOW;
strcat(path, ino_lookup_arg.name);
(*path_len) -= len;
}
if (*path_len < btrfs_stack_root_ref_name_len(backref_item))
return -EOVERFLOW;
strncat(path, (char *)(backref_item + 1),
btrfs_stack_root_ref_name_len(backref_item));
(*path_len) -= btrfs_stack_root_ref_name_len(backref_item);
return 0;
}
#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
static int count_bytes(void *buf, int len, char b)
{
int cnt = 0;
int i;
for (i = 0; i < len; i++) {
if (((char *)buf)[i] == b)
cnt++;
}
return cnt;
}
void subvol_uuid_search_add(struct subvol_uuid_search *s,
struct subvol_info *si)
{
int cnt;
tree_insert(&s->root_id_subvols, si, subvol_search_by_root_id);
tree_insert(&s->path_subvols, si, subvol_search_by_path);
cnt = count_bytes(si->uuid, BTRFS_UUID_SIZE, 0);
if (cnt != BTRFS_UUID_SIZE)
tree_insert(&s->local_subvols, si, subvol_search_by_uuid);
cnt = count_bytes(si->received_uuid, BTRFS_UUID_SIZE, 0);
if (cnt != BTRFS_UUID_SIZE)
tree_insert(&s->received_subvols, si,
subvol_search_by_received_uuid);
}
static struct subvol_info *tree_search(struct rb_root *root,
u64 root_id, const u8 *uuid,
u64 stransid, const char *path,
enum subvol_search_type type)
{
struct rb_node *n = root->rb_node;
struct subvol_info *entry;
__s64 comp;
while (n) {
if (type == subvol_search_by_received_uuid) {
entry = rb_entry(n, struct subvol_info,
rb_received_node);
comp = memcmp(entry->received_uuid, uuid,
BTRFS_UUID_SIZE);
if (!comp) {
if (entry->stransid < stransid)
comp = -1;
else if (entry->stransid > stransid)
comp = 1;
else
comp = 0;
}
} else if (type == subvol_search_by_uuid) {
entry = rb_entry(n, struct subvol_info, rb_local_node);
comp = memcmp(entry->uuid, uuid, BTRFS_UUID_SIZE);
} else if (type == subvol_search_by_root_id) {
entry = rb_entry(n, struct subvol_info,
rb_root_id_node);
comp = entry->root_id - root_id;
} else if (type == subvol_search_by_path) {
entry = rb_entry(n, struct subvol_info, rb_path_node);
comp = strcmp(entry->path, path);
} else {
BUG();
}
if (comp < 0)
n = n->rb_left;
else if (comp > 0)
n = n->rb_right;
else
return entry;
}
return NULL;
}
/*
* this function will be only called if kernel doesn't support uuid tree.
*/
static struct subvol_info *subvol_uuid_search_old(struct subvol_uuid_search *s,
u64 root_id, const u8 *uuid, u64 transid,
const char *path,
enum subvol_search_type type)
{
struct rb_root *root;
if (type == subvol_search_by_received_uuid)
root = &s->received_subvols;
else if (type == subvol_search_by_uuid)
root = &s->local_subvols;
else if (type == subvol_search_by_root_id)
root = &s->root_id_subvols;
else if (type == subvol_search_by_path)
root = &s->path_subvols;
else
return NULL;
return tree_search(root, root_id, uuid, transid, path, type);
}
#else
void subvol_uuid_search_add(struct subvol_uuid_search *s,
struct subvol_info *si)
{
if (si) {
free(si->path);
free(si);
}
}
#endif
struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
u64 root_id, const u8 *uuid, u64 transid,
const char *path,
enum subvol_search_type type)
{
struct subvol_info *si;
si = subvol_uuid_search2(s, root_id, uuid, transid, path, type);
if (IS_ERR(si))
return NULL;
return si;
}
struct subvol_info *subvol_uuid_search2(struct subvol_uuid_search *s,
u64 root_id, const u8 *uuid, u64 transid,
const char *path,
enum subvol_search_type type)
{
int ret = 0;
struct btrfs_root_item root_item;
struct subvol_info *info = NULL;
#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
if (!s->uuid_tree_existed)
return subvol_uuid_search_old(s, root_id, uuid, transid,
path, type);
#endif
switch (type) {
case subvol_search_by_received_uuid:
ret = btrfs_lookup_uuid_received_subvol_item(s->mnt_fd, uuid,
&root_id);
break;
case subvol_search_by_uuid:
ret = btrfs_lookup_uuid_subvol_item(s->mnt_fd, uuid, &root_id);
break;
case subvol_search_by_root_id:
break;
case subvol_search_by_path:
ret = btrfs_get_root_id_by_sub_path(s->mnt_fd, path, &root_id);
break;
default:
ret = -EINVAL;
break;
}
if (ret)
goto out;
ret = btrfs_read_root_item(s->mnt_fd, root_id, &root_item);
if (ret)
goto out;
info = calloc(1, sizeof(*info));
if (!info) {
ret = -ENOMEM;
goto out;
}
info->root_id = root_id;
memcpy(info->uuid, root_item.uuid, BTRFS_UUID_SIZE);
memcpy(info->received_uuid, root_item.received_uuid, BTRFS_UUID_SIZE);
memcpy(info->parent_uuid, root_item.parent_uuid, BTRFS_UUID_SIZE);
info->ctransid = btrfs_root_ctransid(&root_item);
info->otransid = btrfs_root_otransid(&root_item);
info->stransid = btrfs_root_stransid(&root_item);
info->rtransid = btrfs_root_rtransid(&root_item);
if (type == subvol_search_by_path) {
info->path = strdup(path);
if (!info->path) {
ret = -ENOMEM;
goto out;
}
} else {
info->path = malloc(PATH_MAX);
if (!info->path) {
ret = -ENOMEM;
goto out;
}
ret = btrfs_subvolid_resolve(s->mnt_fd, info->path,
PATH_MAX, root_id);
}
out:
if (ret) {
if (info) {
free(info->path);
free(info);
}
return ERR_PTR(ret);
}
return info;
}
#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
static int is_uuid_tree_supported(int fd)
{
int ret;
struct btrfs_ioctl_search_args args;
struct btrfs_ioctl_search_key *sk = &args.key;
memset(&args, 0, sizeof(args));
sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
sk->min_objectid = BTRFS_UUID_TREE_OBJECTID;
sk->max_objectid = BTRFS_UUID_TREE_OBJECTID;
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 = 1;
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
if (ret < 0)
return ret;
/* the ioctl returns the number of item it found in nr_items */
if (sk->nr_items == 0)
return 0;
return 1;
}
/*
* this function is mainly used to read all root items
* it will be only used when we use older kernel which uuid
* tree is not supported yet
*/
int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
{
int ret;
struct btrfs_ioctl_search_args args;
struct btrfs_ioctl_search_key *sk = &args.key;
struct btrfs_ioctl_search_header *sh;
struct btrfs_root_item *root_item_ptr;
struct btrfs_root_item root_item = {};
struct subvol_info *si = NULL;
int root_item_valid = 0;
unsigned long off = 0;
int i;
char *path;
s->mnt_fd = mnt_fd;
s->root_id_subvols = RB_ROOT;
s->local_subvols = RB_ROOT;
s->received_subvols = RB_ROOT;
s->path_subvols = RB_ROOT;
ret = is_uuid_tree_supported(mnt_fd);
if (ret < 0) {
fprintf(stderr,
"ERROR: check if we support uuid tree fails - %m\n");
return ret;
} else if (ret) {
/* uuid tree is supported */
s->uuid_tree_existed = 1;
return 0;
}
memset(&args, 0, sizeof(args));
sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
sk->max_objectid = (u64)-1;
sk->max_offset = (u64)-1;
sk->max_transid = (u64)-1;
sk->min_type = BTRFS_ROOT_ITEM_KEY;
sk->max_type = BTRFS_ROOT_BACKREF_KEY;
sk->nr_items = 4096;
while (1) {
ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
if (ret < 0) {
fprintf(stderr, "ERROR: can't perform the search - %m\n");
return ret;
}
if (sk->nr_items == 0)
break;
off = 0;
for (i = 0; i < sk->nr_items; i++) {
sh = (struct btrfs_ioctl_search_header *)(args.buf +
off);
off += sizeof(*sh);
if ((btrfs_search_header_objectid(sh) != 5 &&
btrfs_search_header_objectid(sh)
< BTRFS_FIRST_FREE_OBJECTID) ||
btrfs_search_header_objectid(sh)
> BTRFS_LAST_FREE_OBJECTID) {
goto skip;
}
if (btrfs_search_header_type(sh)
== BTRFS_ROOT_ITEM_KEY) {
/* older kernels don't have uuids+times */
if (btrfs_search_header_len(sh)
< sizeof(root_item)) {
root_item_valid = 0;
goto skip;
}
root_item_ptr = (struct btrfs_root_item *)
(args.buf + off);
memcpy(&root_item, root_item_ptr,
sizeof(root_item));
root_item_valid = 1;
} else if (btrfs_search_header_type(sh)
== BTRFS_ROOT_BACKREF_KEY ||
root_item_valid) {
if (!root_item_valid)
goto skip;
path = btrfs_list_path_for_root(mnt_fd,
btrfs_search_header_objectid(sh));
if (!path)
path = strdup("");
if (IS_ERR(path)) {
ret = PTR_ERR(path);
fprintf(stderr, "ERROR: unable to "
"resolve path "
"for root %llu\n",
btrfs_search_header_objectid(sh));
goto out;
}
si = calloc(1, sizeof(*si));
si->root_id = btrfs_search_header_objectid(sh);
memcpy(si->uuid, root_item.uuid,
BTRFS_UUID_SIZE);
memcpy(si->parent_uuid, root_item.parent_uuid,
BTRFS_UUID_SIZE);
memcpy(si->received_uuid,
root_item.received_uuid,
BTRFS_UUID_SIZE);
si->ctransid = btrfs_root_ctransid(&root_item);
si->otransid = btrfs_root_otransid(&root_item);
si->stransid = btrfs_root_stransid(&root_item);
si->rtransid = btrfs_root_rtransid(&root_item);
si->path = path;
subvol_uuid_search_add(s, si);
root_item_valid = 0;
} else {
goto skip;
}
skip:
off += btrfs_search_header_len(sh);
/*
* record the mins in sk so we can make sure the
* next search doesn't repeat this root
*/
sk->min_objectid = btrfs_search_header_objectid(sh);
sk->min_offset = btrfs_search_header_offset(sh);
sk->min_type = btrfs_search_header_type(sh);
}
sk->nr_items = 4096;
if (sk->min_offset < (u64)-1)
sk->min_offset++;
else if (sk->min_objectid < (u64)-1) {
sk->min_objectid++;
sk->min_offset = 0;
sk->min_type = 0;
} else
break;
}
out:
return ret;
}
void subvol_uuid_search_finit(struct subvol_uuid_search *s)
{
struct rb_root *root = &s->root_id_subvols;
struct rb_node *node;
if (!s->uuid_tree_existed)
return;
while ((node = rb_first(root))) {
struct subvol_info *entry =
rb_entry(node, struct subvol_info, rb_root_id_node);
free(entry->path);
rb_erase(node, root);
free(entry);
}
s->root_id_subvols = RB_ROOT;
s->local_subvols = RB_ROOT;
s->received_subvols = RB_ROOT;
s->path_subvols = RB_ROOT;
}
#else
int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
{
s->mnt_fd = mnt_fd;
return 0;
}
void subvol_uuid_search_finit(struct subvol_uuid_search *s)
{
}
#endif
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