e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include <stdlib.h>

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include <sys/vfs.h>

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include <sys/stat.h>

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#ifdef HAVE_LINUX_BTRFS_H

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include <linux/btrfs.h>

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#endif

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include "missing.h"

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include "util.h"

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include "path-util.h"

cc3773810855956bad92337cee8fa193584ab62eLennart Poettering#include "macro.h"

cc3773810855956bad92337cee8fa193584ab62eLennart Poettering#include "copy.h"

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include "selinux-util.h"

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include "smack-util.h"

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering#include "fileio.h"

65b5116220a8ebf8a260716152409aa05377aaccLennart Poettering#include "btrfs-ctree.h"

65b5116220a8ebf8a260716152409aa05377aaccLennart Poettering#include "btrfs-util.h"

e9d21f240704f87c6bb5f7fca1c5e6d0f31c84cdLennart Poettering

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;

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;

return !!(flags & BTRFS_SUBVOL_RDONLY);

}

int btrfs_reflink(int infd, int outfd) {

struct stat st;

int r;

assert(infd >= 0);

assert(outfd >= 0);

/* Make sure we invoke the ioctl on a regular file, so that no

if (fstat(outfd, &st) < 0)

return -errno;

if (!S_ISREG(st.st_mode))

return -EINVAL;

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,

};

struct stat st;

int r;

assert(infd >= 0);

assert(outfd >= 0);

assert(sz > 0);

if (fstat(outfd, &st) < 0)

return -errno;

if (!S_ISREG(st.st_mode))

return -EINVAL;

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;

int r;

assert(fd >= 0);

assert(dev);

r = btrfs_is_filesystem(fd);

if (r < 0)

return r;

if (!r)

return -ENOTTY;

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

};

int r;

assert(fd >= 0);

assert(ret);

r = btrfs_is_filesystem(fd);

if (r < 0)

return r;

if (!r)

return -ENOTTY;

if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args) < 0)

return -errno;

*ret = args.treeid;

return 0;

}

int btrfs_subvol_get_id(int fd, const char *subvol, uint64_t *ret) {

_cleanup_close_ int subvol_fd = -1;

assert(fd >= 0);

assert(ret);

subvol_fd = openat(fd, subvol, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);

if (subvol_fd < 0)

return -errno;

return btrfs_subvol_get_id_fd(subvol_fd, ret);

}

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,

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) {

struct stat st;

assert(fd >= 0);

if (fstat(fd, &st) < 0)

return -errno;

if (!S_ISREG(st.st_mode))

return -EINVAL;

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,

};

int r;

assert(fd >= 0);

r = btrfs_is_filesystem(fd);

if (r < 0)

return r;

if (!r)

return -ENOTTY;

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,

};

int r;

assert(fd >= 0);

r = btrfs_is_filesystem(fd);

if (r < 0)

return r;

if (!r)

return -ENOTTY;

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;

struct stat st;

bool made_writable = false;

int r;

assert(fd >= 0);

assert(subvolume);

if (fstat(fd, &st) < 0)

return -errno;

if (!S_ISDIR(st.st_mode))

return -EINVAL;

/* First, try to remove the subvolume. If it happens to be

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

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 (!made_writable) {

r = btrfs_subvol_set_read_only_fd(subvol_fd, false);

if (r < 0)

return r;

made_writable = true;

}

if (isempty(ino_args.name))

/* Subvolume is in the top-level

r = subvol_remove_children(subvol_fd, p, sh->objectid, recursive);

else {

_cleanup_close_ int child_fd = -1;

/* Subvolume is somewhere further down,

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

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 old_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,

};

_cleanup_close_ int subvolume_fd = -1;

uint64_t new_subvol_id;

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 (old_subvol_id == 0) {

r = btrfs_subvol_get_id_fd(old_fd, &old_subvol_id);

if (r < 0)

return r;

}

r = btrfs_subvol_get_id(new_fd, vol_args.name, &new_subvol_id);

if (r < 0)

return r;

args.key.min_offset = args.key.max_offset = old_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;

/* Avoid finding the source subvolume a second

if (sh->offset != old_subvol_id)

continue;

/* Avoid running into loops if the new

if (sh->objectid == new_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 = old_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

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;

if (flags & BTRFS_SNAPSHOT_READ_ONLY) {

/* If the snapshot is read-only we

if (subvolume_fd < 0) {

subvolume_fd = openat(new_fd, subvolume, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);

if (subvolume_fd < 0)

return -errno;

}

r = btrfs_subvol_set_read_only_fd(subvolume_fd, false);

if (r < 0)

return r;

}

/* When btrfs clones the subvolumes, child

if (unlinkat(new_child_fd, p, AT_REMOVEDIR) < 0) {

int k = -errno;

if (flags & BTRFS_SNAPSHOT_READ_ONLY)

(void) btrfs_subvol_set_read_only_fd(subvolume_fd, true);

return k;

}

r = subvol_snapshot_children(old_child_fd, new_child_fd, p, sh->objectid, flags & ~BTRFS_SNAPSHOT_FALLBACK_COPY);

/* Restore the readonly flag */

if (flags & BTRFS_SNAPSHOT_READ_ONLY) {

int k;

k = btrfs_subvol_set_read_only_fd(subvolume_fd, true);

if (r >= 0 && k < 0)

return k;

}

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);

}