btrfs-util.c revision f2cbe59e113f08549949a76ac5b9b3972df4cc30
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2014 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdlib.h>
#include <sys/vfs.h>
#include <sys/stat.h>
#ifdef HAVE_LINUX_BTRFS_H
#include <linux/btrfs.h>
#endif
#include "missing.h"
#include "util.h"
#include "path-util.h"
#include "macro.h"
#include "strv.h"
#include "copy.h"
#include "btrfs-util.h"
static int validate_subvolume_name(const char *name) {
if (!filename_is_valid(name))
return -EINVAL;
if (strlen(name) > BTRFS_SUBVOL_NAME_MAX)
return -E2BIG;
return 0;
}
static int open_parent(const char *path, int flags) {
_cleanup_free_ char *parent = NULL;
int r, fd;
assert(path);
r = path_get_parent(path, &parent);
if (r < 0)
return r;
fd = open(parent, flags);
if (fd < 0)
return -errno;
return fd;
}
static int extract_subvolume_name(const char *path, const char **subvolume) {
const char *fn;
int r;
assert(path);
assert(subvolume);
fn = basename(path);
r = validate_subvolume_name(fn);
if (r < 0)
return r;
*subvolume = fn;
return 0;
}
int btrfs_is_snapshot(int fd) {
struct stat st;
struct statfs sfs;
if (fstatfs(fd, &sfs) < 0)
return -errno;
if (!F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
return 0;
if (fstat(fd, &st) < 0)
return -errno;
/* On btrfs subvolumes always have the inode 256 */
return S_ISDIR(st.st_mode) && st.st_ino == 256;
}
int btrfs_subvol_snapshot(const char *old_path, const char *new_path, bool read_only, bool fallback_copy) {
struct btrfs_ioctl_vol_args_v2 args = {
.flags = read_only ? BTRFS_SUBVOL_RDONLY : 0,
};
_cleanup_close_ int old_fd = -1, new_fd = -1;
const char *subvolume;
int r;
assert(old_path);
old_fd = open(old_path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (old_fd < 0)
return -errno;
r = btrfs_is_snapshot(old_fd);
if (r < 0)
return r;
if (r == 0) {
if (fallback_copy) {
r = btrfs_subvol_make(new_path);
if (r < 0)
return r;
r = copy_directory_fd(old_fd, new_path, true);
if (r < 0) {
btrfs_subvol_remove(new_path);
return r;
}
if (read_only) {
r = btrfs_subvol_read_only(new_path, true);
if (r < 0) {
btrfs_subvol_remove(new_path);
return r;
}
}
return 0;
}
return -EISDIR;
}
r = extract_subvolume_name(new_path, &subvolume);
if (r < 0)
return r;
new_fd = open_parent(new_path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (new_fd < 0)
return new_fd;
strncpy(args.name, subvolume, sizeof(args.name)-1);
args.fd = old_fd;
if (ioctl(new_fd, BTRFS_IOC_SNAP_CREATE_V2, &args) < 0)
return -errno;
return 0;
}
int btrfs_subvol_make(const char *path) {
struct btrfs_ioctl_vol_args args = {};
_cleanup_close_ int fd = -1;
const char *subvolume;
int r;
assert(path);
r = extract_subvolume_name(path, &subvolume);
if (r < 0)
return r;
fd = open_parent(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0)
return fd;
strncpy(args.name, subvolume, sizeof(args.name)-1);
if (ioctl(fd, BTRFS_IOC_SUBVOL_CREATE, &args) < 0)
return -errno;
return 0;
}
int btrfs_subvol_remove(const char *path) {
struct btrfs_ioctl_vol_args args = {};
_cleanup_close_ int fd = -1;
const char *subvolume;
int r;
assert(path);
r = extract_subvolume_name(path, &subvolume);
if (r < 0)
return r;
fd = open_parent(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0)
return fd;
strncpy(args.name, subvolume, sizeof(args.name)-1);
if (ioctl(fd, BTRFS_IOC_SNAP_DESTROY, &args) < 0)
return -errno;
return 0;
}
int btrfs_subvol_read_only(const char *path, bool b) {
_cleanup_close_ int fd = -1;
uint64_t flags, nflags;
fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return -errno;
if (ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags) < 0)
return -errno;
if (b)
nflags = flags | BTRFS_SUBVOL_RDONLY;
else
nflags = flags & ~BTRFS_SUBVOL_RDONLY;
if (flags == nflags)
return 0;
if (ioctl(fd, BTRFS_IOC_SUBVOL_SETFLAGS, &nflags) < 0)
return -errno;
return 0;
}
int btrfs_reflink(int infd, int outfd) {
int r;
assert(infd >= 0);
assert(outfd >= 0);
r = ioctl(outfd, BTRFS_IOC_CLONE, infd);
if (r < 0)
return -errno;
return 0;
}
int btrfs_get_block_device(const char *path, dev_t *dev) {
struct btrfs_ioctl_fs_info_args fsi = {};
_cleanup_close_ int fd = -1;
uint64_t id;
assert(path);
assert(dev);
fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0)
return -errno;
if (ioctl(fd, BTRFS_IOC_FS_INFO, &fsi) < 0)
return -errno;
/* We won't do this for btrfs RAID */
if (fsi.num_devices != 1)
return 0;
for (id = 1; id <= fsi.max_id; id++) {
struct btrfs_ioctl_dev_info_args di = {
.devid = id,
};
struct stat st;
if (ioctl(fd, BTRFS_IOC_DEV_INFO, &di) < 0) {
if (errno == ENODEV)
continue;
return -errno;
}
if (stat((char*) di.path, &st) < 0)
return -errno;
if (!S_ISBLK(st.st_mode))
return -ENODEV;
if (major(st.st_rdev) == 0)
return -ENODEV;
*dev = st.st_rdev;
return 1;
}
return -ENODEV;
}