btrfs-util.c revision 21222ea5cdec65fa30a75bd5a78475459075b946
/*-*- 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 "copy.h"
#include "selinux-util.h"
#include "smack-util.h"
#include "fileio.h"
#include "btrfs-ctree.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_filesystem(int fd) {
struct statfs sfs;
assert(fd >= 0);
if (fstatfs(fd, &sfs) < 0)
return -errno;
return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC);
}
int btrfs_is_subvol(int fd) {
struct stat st;
assert(fd >= 0);
/* On btrfs subvolumes always have the inode 256 */
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode) || st.st_ino != 256)
return 0;
return btrfs_is_filesystem(fd);
}
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_make_label(const char *path) {
int r;
assert(path);
r = mac_selinux_create_file_prepare(path, S_IFDIR);
if (r < 0)
return r;
r = btrfs_subvol_make(path);
mac_selinux_create_file_clear();
if (r < 0)
return r;
return mac_smack_fix(path, false, false);
}
int btrfs_subvol_set_read_only_fd(int fd, bool b) {
uint64_t flags, nflags;
struct stat st;
assert(fd >= 0);
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode) || st.st_ino != 256)
return -EINVAL;
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_subvol_set_read_only(const char *path, bool b) {
_cleanup_close_ int fd = -1;
fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0)
return -errno;
return btrfs_subvol_set_read_only_fd(fd, b);
}
int btrfs_subvol_get_read_only_fd(int fd) {
uint64_t flags;
if (ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags) < 0)
return -errno;
return !!(flags & BTRFS_SUBVOL_RDONLY);
}
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_clone_range(int infd, uint64_t in_offset, int outfd, uint64_t out_offset, uint64_t sz) {
struct btrfs_ioctl_clone_range_args args = {
.src_fd = infd,
.src_offset = in_offset,
.src_length = sz,
.dest_offset = out_offset,
};
int r;
assert(infd >= 0);
assert(outfd >= 0);
assert(sz > 0);
r = ioctl(outfd, BTRFS_IOC_CLONE_RANGE, &args);
if (r < 0)
return -errno;
return 0;
}
int btrfs_get_block_device_fd(int fd, dev_t *dev) {
struct btrfs_ioctl_fs_info_args fsi = {};
uint64_t id;
assert(fd >= 0);
assert(dev);
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;
}
int btrfs_get_block_device(const char *path, dev_t *dev) {
_cleanup_close_ int fd = -1;
assert(path);
assert(dev);
fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return -errno;
return btrfs_get_block_device_fd(fd, dev);
}
int btrfs_subvol_get_id_fd(int fd, uint64_t *ret) {
struct btrfs_ioctl_ino_lookup_args args = {
.objectid = BTRFS_FIRST_FREE_OBJECTID
};
assert(fd >= 0);
assert(ret);
if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args) < 0)
return -errno;
*ret = args.treeid;
return 0;
}
static bool btrfs_ioctl_search_args_inc(struct btrfs_ioctl_search_args *args) {
assert(args);
/* the objectid, type, offset together make up the btrfs key,
* which is considered a single 136byte integer when
* comparing. This call increases the counter by one, dealing
* with the overflow between the overflows */
if (args->key.min_offset < (uint64_t) -1) {
args->key.min_offset++;
return true;
}
if (args->key.min_type < (uint8_t) -1) {
args->key.min_type++;
args->key.min_offset = 0;
return true;
}
if (args->key.min_objectid < (uint64_t) -1) {
args->key.min_objectid++;
args->key.min_offset = 0;
args->key.min_type = 0;
return true;
}
return 0;
}
static void btrfs_ioctl_search_args_set(struct btrfs_ioctl_search_args *args, const struct btrfs_ioctl_search_header *h) {
assert(args);
assert(h);
args->key.min_objectid = h->objectid;
args->key.min_type = h->type;
args->key.min_offset = h->offset;
}
static int btrfs_ioctl_search_args_compare(const struct btrfs_ioctl_search_args *args) {
assert(args);
/* Compare min and max */
if (args->key.min_objectid < args->key.max_objectid)
return -1;
if (args->key.min_objectid > args->key.max_objectid)
return 1;
if (args->key.min_type < args->key.max_type)
return -1;
if (args->key.min_type > args->key.max_type)
return 1;
if (args->key.min_offset < args->key.max_offset)
return -1;
if (args->key.min_offset > args->key.max_offset)
return 1;
return 0;
}
#define FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) \
for ((i) = 0, \
(sh) = (const struct btrfs_ioctl_search_header*) (args).buf; \
(i) < (args).key.nr_items; \
(i)++, \
(sh) = (const struct btrfs_ioctl_search_header*) ((uint8_t*) (sh) + sizeof(struct btrfs_ioctl_search_header) + (sh)->len))
#define BTRFS_IOCTL_SEARCH_HEADER_BODY(sh) \
((void*) ((uint8_t*) sh + sizeof(struct btrfs_ioctl_search_header)))
int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *ret) {
struct btrfs_ioctl_search_args args = {
/* Tree of tree roots */
.key.tree_id = BTRFS_ROOT_TREE_OBJECTID,
/* Look precisely for the subvolume items */
.key.min_type = BTRFS_ROOT_ITEM_KEY,
.key.max_type = BTRFS_ROOT_ITEM_KEY,
.key.min_offset = 0,
.key.max_offset = (uint64_t) -1,
/* No restrictions on the other components */
.key.min_transid = 0,
.key.max_transid = (uint64_t) -1,
};
uint64_t subvol_id;
bool found = false;
int r;
assert(fd >= 0);
assert(ret);
r = btrfs_subvol_get_id_fd(fd, &subvol_id);
if (r < 0)
return r;
args.key.min_objectid = args.key.max_objectid = subvol_id;
while (btrfs_ioctl_search_args_compare(&args) <= 0) {
const struct btrfs_ioctl_search_header *sh;
unsigned i;
args.key.nr_items = 256;
if (ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args) < 0)
return -errno;
if (args.key.nr_items <= 0)
break;
FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) {
const struct btrfs_root_item *ri;
/* Make sure we start the next search at least from this entry */
btrfs_ioctl_search_args_set(&args, sh);
if (sh->objectid != subvol_id)
continue;
if (sh->type != BTRFS_ROOT_ITEM_KEY)
continue;
/* Older versions of the struct lacked the otime setting */
if (sh->len < offsetof(struct btrfs_root_item, otime) + sizeof(struct btrfs_timespec))
continue;
ri = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
ret->otime = (usec_t) le64toh(ri->otime.sec) * USEC_PER_SEC +
(usec_t) le32toh(ri->otime.nsec) / NSEC_PER_USEC;
ret->subvol_id = subvol_id;
ret->read_only = !!(le64toh(ri->flags) & BTRFS_ROOT_SUBVOL_RDONLY);
assert_cc(sizeof(ri->uuid) == sizeof(ret->uuid));
memcpy(&ret->uuid, ri->uuid, sizeof(ret->uuid));
memcpy(&ret->parent_uuid, ri->parent_uuid, sizeof(ret->parent_uuid));
found = true;
goto finish;
}
/* Increase search key by one, to read the next item, if we can. */
if (!btrfs_ioctl_search_args_inc(&args))
break;
}
finish:
if (!found)
return -ENODATA;
return 0;
}
int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *ret) {
struct btrfs_ioctl_search_args args = {
/* Tree of quota items */
.key.tree_id = BTRFS_QUOTA_TREE_OBJECTID,
/* The object ID is always 0 */
.key.min_objectid = 0,
.key.max_objectid = 0,
/* Look precisely for the quota items */
.key.min_type = BTRFS_QGROUP_STATUS_KEY,
.key.max_type = BTRFS_QGROUP_LIMIT_KEY,
/* No restrictions on the other components */
.key.min_transid = 0,
.key.max_transid = (uint64_t) -1,
};
uint64_t subvol_id;
bool found_info = false, found_limit = false;
int r;
assert(fd >= 0);
assert(ret);
r = btrfs_subvol_get_id_fd(fd, &subvol_id);
if (r < 0)
return r;
args.key.min_offset = args.key.max_offset = subvol_id;
while (btrfs_ioctl_search_args_compare(&args) <= 0) {
const struct btrfs_ioctl_search_header *sh;
unsigned i;
args.key.nr_items = 256;
if (ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args) < 0)
return -errno;
if (args.key.nr_items <= 0)
break;
FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) {
/* Make sure we start the next search at least from this entry */
btrfs_ioctl_search_args_set(&args, sh);
if (sh->objectid != 0)
continue;
if (sh->offset != subvol_id)
continue;
if (sh->type == BTRFS_QGROUP_INFO_KEY) {
const struct btrfs_qgroup_info_item *qii = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
ret->referenced = le64toh(qii->rfer);
ret->exclusive = le64toh(qii->excl);
found_info = true;
} else if (sh->type == BTRFS_QGROUP_LIMIT_KEY) {
const struct btrfs_qgroup_limit_item *qli = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
ret->referenced_max = le64toh(qli->max_rfer);
ret->exclusive_max = le64toh(qli->max_excl);
if (ret->referenced_max == 0)
ret->referenced_max = (uint64_t) -1;
if (ret->exclusive_max == 0)
ret->exclusive_max = (uint64_t) -1;
found_limit = true;
}
if (found_info && found_limit)
goto finish;
}
/* Increase search key by one, to read the next item, if we can. */
if (!btrfs_ioctl_search_args_inc(&args))
break;
}
finish:
if (!found_limit && !found_info)
return -ENODATA;
if (!found_info) {
ret->referenced = (uint64_t) -1;
ret->exclusive = (uint64_t) -1;
}
if (!found_limit) {
ret->referenced_max = (uint64_t) -1;
ret->exclusive_max = (uint64_t) -1;
}
return 0;
}
int btrfs_defrag_fd(int fd) {
assert(fd >= 0);
if (ioctl(fd, BTRFS_IOC_DEFRAG, NULL) < 0)
return -errno;
return 0;
}
int btrfs_defrag(const char *p) {
_cleanup_close_ int fd = -1;
fd = open(p, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd < 0)
return -errno;
return btrfs_defrag_fd(fd);
}
int btrfs_quota_enable_fd(int fd, bool b) {
struct btrfs_ioctl_quota_ctl_args args = {
.cmd = b ? BTRFS_QUOTA_CTL_ENABLE : BTRFS_QUOTA_CTL_DISABLE,
};
assert(fd >= 0);
if (ioctl(fd, BTRFS_IOC_QUOTA_CTL, &args) < 0)
return -errno;
return 0;
}
int btrfs_quota_enable(const char *path, bool b) {
_cleanup_close_ int fd = -1;
fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd < 0)
return -errno;
return btrfs_quota_enable_fd(fd, b);
}
int btrfs_quota_limit_fd(int fd, uint64_t referenced_max) {
struct btrfs_ioctl_qgroup_limit_args args = {
.lim.max_rfer =
referenced_max == (uint64_t) -1 ? 0 :
referenced_max == 0 ? 1 : referenced_max,
.lim.flags = BTRFS_QGROUP_LIMIT_MAX_RFER,
};
assert(fd >= 0);
if (ioctl(fd, BTRFS_IOC_QGROUP_LIMIT, &args) < 0)
return -errno;
return 0;
}
int btrfs_quota_limit(const char *path, uint64_t referenced_max) {
_cleanup_close_ int fd = -1;
fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd < 0)
return -errno;
return btrfs_quota_limit_fd(fd, referenced_max);
}
int btrfs_resize_loopback_fd(int fd, uint64_t new_size, bool grow_only) {
struct btrfs_ioctl_vol_args args = {};
_cleanup_free_ char *p = NULL, *loop = NULL, *backing = NULL;
_cleanup_close_ int loop_fd = -1, backing_fd = -1;
struct stat st;
dev_t dev = 0;
int r;
/* btrfs cannot handle file systems < 16M, hence use this as minimum */
if (new_size < 16*1024*1024)
new_size = 16*1024*1024;
r = btrfs_get_block_device_fd(fd, &dev);
if (r < 0)
return r;
if (r == 0)
return -ENODEV;
if (asprintf(&p, "/sys/dev/block/%u:%u/loop/backing_file", major(dev), minor(dev)) < 0)
return -ENOMEM;
r = read_one_line_file(p, &backing);
if (r == -ENOENT)
return -ENODEV;
if (r < 0)
return r;
if (isempty(backing) || !path_is_absolute(backing))
return -ENODEV;
backing_fd = open(backing, O_RDWR|O_CLOEXEC|O_NOCTTY);
if (backing_fd < 0)
return -errno;
if (fstat(backing_fd, &st) < 0)
return -errno;
if (!S_ISREG(st.st_mode))
return -ENODEV;
if (new_size == (uint64_t) st.st_size)
return 0;
if (grow_only && new_size < (uint64_t) st.st_size)
return -EINVAL;
if (asprintf(&loop, "/dev/block/%u:%u", major(dev), minor(dev)) < 0)
return -ENOMEM;
loop_fd = open(loop, O_RDWR|O_CLOEXEC|O_NOCTTY);
if (loop_fd < 0)
return -errno;
if (snprintf(args.name, sizeof(args.name), "%" PRIu64, new_size) >= (int) sizeof(args.name))
return -EINVAL;
if (new_size < (uint64_t) st.st_size) {
/* Decrease size: first decrease btrfs size, then shorten loopback */
if (ioctl(fd, BTRFS_IOC_RESIZE, &args) < 0)
return -errno;
}
if (ftruncate(backing_fd, new_size) < 0)
return -errno;
if (ioctl(loop_fd, LOOP_SET_CAPACITY, 0) < 0)
return -errno;
if (new_size > (uint64_t) st.st_size) {
/* Increase size: first enlarge loopback, then increase btrfs size */
if (ioctl(fd, BTRFS_IOC_RESIZE, &args) < 0)
return -errno;
}
/* Make sure the free disk space is correctly updated for both file systems */
(void) fsync(fd);
(void) fsync(backing_fd);
return 1;
}
int btrfs_resize_loopback(const char *p, uint64_t new_size, bool grow_only) {
_cleanup_close_ int fd = -1;
fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return -errno;
return btrfs_resize_loopback_fd(fd, new_size, grow_only);
}
static int subvol_remove_children(int fd, const char *subvolume, uint64_t subvol_id, bool recursive) {
struct btrfs_ioctl_search_args args = {
.key.tree_id = BTRFS_ROOT_TREE_OBJECTID,
.key.min_objectid = BTRFS_FIRST_FREE_OBJECTID,
.key.max_objectid = BTRFS_LAST_FREE_OBJECTID,
.key.min_type = BTRFS_ROOT_BACKREF_KEY,
.key.max_type = BTRFS_ROOT_BACKREF_KEY,
.key.min_transid = 0,
.key.max_transid = (uint64_t) -1,
};
struct btrfs_ioctl_vol_args vol_args = {};
_cleanup_close_ int subvol_fd = -1;
int r;
assert(fd >= 0);
assert(subvolume);
/* First, try to remove the subvolume. If it happens to be
* already empty, this will just work. */
strncpy(vol_args.name, subvolume, sizeof(vol_args.name)-1);
if (ioctl(fd, BTRFS_IOC_SNAP_DESTROY, &vol_args) >= 0)
return 0;
if (!recursive || errno != ENOTEMPTY)
return -errno;
/* OK, the subvolume is not empty, let's look for child
* subvolumes, and remove them, first */
subvol_fd = openat(fd, subvolume, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (subvol_fd < 0)
return -errno;
if (subvol_id == 0) {
r = btrfs_subvol_get_id_fd(subvol_fd, &subvol_id);
if (r < 0)
return r;
}
args.key.min_offset = args.key.max_offset = subvol_id;
while (btrfs_ioctl_search_args_compare(&args) <= 0) {
const struct btrfs_ioctl_search_header *sh;
unsigned i;
args.key.nr_items = 256;
if (ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args) < 0)
return -errno;
if (args.key.nr_items <= 0)
break;
FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) {
_cleanup_free_ char *p = NULL;
const struct btrfs_root_ref *ref;
struct btrfs_ioctl_ino_lookup_args ino_args;
btrfs_ioctl_search_args_set(&args, sh);
if (sh->type != BTRFS_ROOT_BACKREF_KEY)
continue;
if (sh->offset != subvol_id)
continue;
ref = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
p = strndup((char*) ref + sizeof(struct btrfs_root_ref), le64toh(ref->name_len));
if (!p)
return -ENOMEM;
zero(ino_args);
ino_args.treeid = subvol_id;
ino_args.objectid = htole64(ref->dirid);
if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0)
return -errno;
if (isempty(ino_args.name))
/* Subvolume is in the top-level
* directory of the subvolume. */
r = subvol_remove_children(subvol_fd, p, sh->objectid, recursive);
else {
_cleanup_close_ int child_fd = -1;
/* Subvolume is somewhere further down,
* hence we need to open the
* containing directory first */
child_fd = openat(subvol_fd, ino_args.name, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (child_fd < 0)
return -errno;
r = subvol_remove_children(child_fd, p, sh->objectid, recursive);
}
if (r < 0)
return r;
}
/* Increase search key by one, to read the next item, if we can. */
if (!btrfs_ioctl_search_args_inc(&args))
break;
}
/* OK, the child subvolumes should all be gone now, let's try
* again to remove the subvolume */
if (ioctl(fd, BTRFS_IOC_SNAP_DESTROY, &vol_args) < 0)
return -errno;
return 0;
}
int btrfs_subvol_remove(const char *path, bool recursive) {
_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;
return subvol_remove_children(fd, subvolume, 0, recursive);
}
int btrfs_subvol_remove_fd(int fd, const char *subvolume, bool recursive) {
return subvol_remove_children(fd, subvolume, 0, recursive);
}
static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolume, uint64_t subvol_id, BtrfsSnapshotFlags flags) {
struct btrfs_ioctl_search_args args = {
.key.tree_id = BTRFS_ROOT_TREE_OBJECTID,
.key.min_objectid = BTRFS_FIRST_FREE_OBJECTID,
.key.max_objectid = BTRFS_LAST_FREE_OBJECTID,
.key.min_type = BTRFS_ROOT_BACKREF_KEY,
.key.max_type = BTRFS_ROOT_BACKREF_KEY,
.key.min_transid = 0,
.key.max_transid = (uint64_t) -1,
};
struct btrfs_ioctl_vol_args_v2 vol_args = {
.flags = flags & BTRFS_SNAPSHOT_READ_ONLY ? BTRFS_SUBVOL_RDONLY : 0,
.fd = old_fd,
};
int r;
assert(old_fd >= 0);
assert(new_fd >= 0);
assert(subvolume);
strncpy(vol_args.name, subvolume, sizeof(vol_args.name)-1);
vol_args.fd = old_fd;
if (ioctl(new_fd, BTRFS_IOC_SNAP_CREATE_V2, &vol_args) < 0)
return -errno;
if (!(flags & BTRFS_SNAPSHOT_RECURSIVE))
return 0;
if (subvol_id == 0) {
r = btrfs_subvol_get_id_fd(old_fd, &subvol_id);
if (r < 0)
return r;
}
args.key.min_offset = args.key.max_offset = subvol_id;
while (btrfs_ioctl_search_args_compare(&args) <= 0) {
const struct btrfs_ioctl_search_header *sh;
unsigned i;
args.key.nr_items = 256;
if (ioctl(old_fd, BTRFS_IOC_TREE_SEARCH, &args) < 0)
return -errno;
if (args.key.nr_items <= 0)
break;
FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) {
_cleanup_free_ char *p = NULL, *c = NULL, *np = NULL;
struct btrfs_ioctl_ino_lookup_args ino_args;
const struct btrfs_root_ref *ref;
_cleanup_close_ int old_child_fd = -1, new_child_fd = -1;
btrfs_ioctl_search_args_set(&args, sh);
if (sh->type != BTRFS_ROOT_BACKREF_KEY)
continue;
if (sh->offset != subvol_id)
continue;
ref = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
p = strndup((char*) ref + sizeof(struct btrfs_root_ref), le64toh(ref->name_len));
if (!p)
return -ENOMEM;
zero(ino_args);
ino_args.treeid = subvol_id;
ino_args.objectid = htole64(ref->dirid);
if (ioctl(old_fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0)
return -errno;
/* The kernel returns an empty name if the
* subvolume is in the top-level directory,
* and otherwise appends a slash, so that we
* can just concatenate easily here, without
* adding a slash. */
c = strappend(ino_args.name, p);
if (!c)
return -ENOMEM;
old_child_fd = openat(old_fd, c, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (old_child_fd < 0)
return -errno;
np = strjoin(subvolume, "/", ino_args.name, NULL);
if (!np)
return -ENOMEM;
new_child_fd = openat(new_fd, np, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (new_child_fd < 0)
return -errno;
/* When btrfs clones the subvolumes, child
* subvolumes appear as directories. Remove
* them, so that we can create a new snapshot
* in their place */
if (unlinkat(new_child_fd, p, AT_REMOVEDIR) < 0)
return -errno;
r = subvol_snapshot_children(old_child_fd, new_child_fd, p, sh->objectid, flags & ~BTRFS_SNAPSHOT_FALLBACK_COPY);
if (r < 0)
return r;
}
/* Increase search key by one, to read the next item, if we can. */
if (!btrfs_ioctl_search_args_inc(&args))
break;
}
return 0;
}
int btrfs_subvol_snapshot_fd(int old_fd, const char *new_path, BtrfsSnapshotFlags flags) {
_cleanup_close_ int new_fd = -1;
const char *subvolume;
int r;
assert(old_fd >= 0);
assert(new_path);
r = btrfs_is_subvol(old_fd);
if (r < 0)
return r;
if (r == 0) {
if (!(flags & BTRFS_SNAPSHOT_FALLBACK_COPY))
return -EISDIR;
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, false);
return r;
}
if (flags & BTRFS_SNAPSHOT_READ_ONLY) {
r = btrfs_subvol_set_read_only(new_path, true);
if (r < 0) {
btrfs_subvol_remove(new_path, false);
return r;
}
}
return 0;
}
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;
return subvol_snapshot_children(old_fd, new_fd, subvolume, 0, flags);
}
int btrfs_subvol_snapshot(const char *old_path, const char *new_path, BtrfsSnapshotFlags flags) {
_cleanup_close_ int old_fd = -1;
assert(old_path);
assert(new_path);
old_fd = open(old_path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (old_fd < 0)
return -errno;
return btrfs_subvol_snapshot_fd(old_fd, new_path, flags);
}