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-rw-r--r--src/shared/btrfs-util.c294
1 files changed, 294 insertions, 0 deletions
diff --git a/src/shared/btrfs-util.c b/src/shared/btrfs-util.c
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+++ b/src/shared/btrfs-util.c
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+/*-*- 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_tree_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;
+}
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