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Systemd/src/basic/btrfs-util.c
Lennart Poettering 17cbb288fa nspawn: add fallback top normal copy/reflink when we cannot btrfs snapshot 
Given that other file systems (notably: xfs) support reflinks these days, let's
extend the file system snapshotting logic to fall back to plan copies or
reflinks when full btrfs subvolume snapshots are not available.

This essentially makes "systemd-nspawn --ephemeral" and "systemd-nspawn
--template=" available on non-btrfs subvolumes. Of course, both operations will
still be slower on non-btrfs than on btrfs (simply because reflinking each file
individually in a directory tree is still slower than doing this in one step
for a whole subvolume), but it's probably good enough for many cases, and we
should provide the users with the tools, they have to figure out what's good
for them.

Note that "machinectl clone" already had a fallback like this in place, this
patch generalizes this, and adds similar support to our other cases.
2016-11-22 13:35:09 +01:00

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/***
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 <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <linux/fs.h>
#include <linux/loop.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/sysmacros.h>
#include <unistd.h>
#ifdef HAVE_LINUX_BTRFS_H
#include <linux/btrfs.h>
#endif
#include "alloc-util.h"
#include "btrfs-ctree.h"
#include "btrfs-util.h"
#include "chattr-util.h"
#include "copy.h"
#include "fd-util.h"
#include "fileio.h"
#include "io-util.h"
#include "macro.h"
#include "missing.h"
#include "path-util.h"
#include "rm-rf.h"
#include "selinux-util.h"
#include "smack-util.h"
#include "sparse-endian.h"
#include "stat-util.h"
#include "string-util.h"
#include "time-util.h"
#include "util.h"
/* WARNING: Be careful with file system ioctls! When we get an fd, we
* need to make sure it either refers to only a regular file or
* directory, or that it is located on btrfs, before invoking any
* btrfs ioctls. The ioctl numbers are reused by some device drivers
* (such as DRM), and hence might have bad effects when invoked on
* device nodes (that reference drivers) rather than fds to normal
* files or directories. */
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 fd;
assert(path);
parent = dirname_malloc(path);
if (!parent)
return -ENOMEM;
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_fd(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_is_subvol(const char *path) {
_cleanup_close_ int fd = -1;
assert(path);
fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0)
return -errno;
return btrfs_is_subvol_fd(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
* device driver accidentally gets it. */
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,
* 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, uint64_t subvol_id, 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,
};
bool found = false;
int r;
assert(fd >= 0);
assert(ret);
if (subvol_id == 0) {
r = btrfs_subvol_get_id_fd(fd, &subvol_id);
if (r < 0)
return r;
} else {
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (!r)
return -ENOTTY;
}
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_qgroup_get_quota_fd(int fd, uint64_t qgroupid, 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,
};
bool found_info = false, found_limit = false;
int r;
assert(fd >= 0);
assert(ret);
if (qgroupid == 0) {
r = btrfs_subvol_get_id_fd(fd, &qgroupid);
if (r < 0)
return r;
} else {
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (!r)
return -ENOTTY;
}
args.key.min_offset = args.key.max_offset = qgroupid;
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) {
if (errno == ENOENT) /* quota tree is missing: quota disabled */
break;
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 != qgroupid)
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);
if (le64toh(qli->flags) & BTRFS_QGROUP_LIMIT_MAX_RFER)
ret->referenced_max = le64toh(qli->max_rfer);
else
ret->referenced_max = (uint64_t) -1;
if (le64toh(qli->flags) & BTRFS_QGROUP_LIMIT_MAX_EXCL)
ret->exclusive_max = le64toh(qli->max_excl);
else
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_qgroup_get_quota(const char *path, uint64_t qgroupid, BtrfsQuotaInfo *ret) {
_cleanup_close_ int fd = -1;
fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd < 0)
return -errno;
return btrfs_qgroup_get_quota_fd(fd, qgroupid, ret);
}
int btrfs_subvol_find_subtree_qgroup(int fd, uint64_t subvol_id, uint64_t *ret) {
uint64_t level, lowest = (uint64_t) -1, lowest_qgroupid = 0;
_cleanup_free_ uint64_t *qgroups = NULL;
int r, n, i;
assert(fd >= 0);
assert(ret);
/* This finds the "subtree" qgroup for a specific
* subvolume. This only works for subvolumes that have been
* prepared with btrfs_subvol_auto_qgroup_fd() with
* insert_intermediary_qgroup=true (or equivalent). For others
* it will return the leaf qgroup instead. The two cases may
* be distuingished via the return value, which is 1 in case
* an appropriate "subtree" qgroup was found, and 0
* otherwise. */
if (subvol_id == 0) {
r = btrfs_subvol_get_id_fd(fd, &subvol_id);
if (r < 0)
return r;
}
r = btrfs_qgroupid_split(subvol_id, &level, NULL);
if (r < 0)
return r;
if (level != 0) /* Input must be a leaf qgroup */
return -EINVAL;
n = btrfs_qgroup_find_parents(fd, subvol_id, &qgroups);
if (n < 0)
return n;
for (i = 0; i < n; i++) {
uint64_t id;
r = btrfs_qgroupid_split(qgroups[i], &level, &id);
if (r < 0)
return r;
if (id != subvol_id)
continue;
if (lowest == (uint64_t) -1 || level < lowest) {
lowest_qgroupid = qgroups[i];
lowest = level;
}
}
if (lowest == (uint64_t) -1) {
/* No suitable higher-level qgroup found, let's return
* the leaf qgroup instead, and indicate that with the
* return value. */
*ret = subvol_id;
return 0;
}
*ret = lowest_qgroupid;
return 1;
}
int btrfs_subvol_get_subtree_quota_fd(int fd, uint64_t subvol_id, BtrfsQuotaInfo *ret) {
uint64_t qgroupid;
int r;
assert(fd >= 0);
assert(ret);
/* This determines the quota data of the qgroup with the
* lowest level, that shares the id part with the specified
* subvolume. This is useful for determining the quota data
* for entire subvolume subtrees, as long as the subtrees have
* been set up with btrfs_qgroup_subvol_auto_fd() or in a
* compatible way */
r = btrfs_subvol_find_subtree_qgroup(fd, subvol_id, &qgroupid);
if (r < 0)
return r;
return btrfs_qgroup_get_quota_fd(fd, qgroupid, ret);
}
int btrfs_subvol_get_subtree_quota(const char *path, uint64_t subvol_id, BtrfsQuotaInfo *ret) {
_cleanup_close_ int fd = -1;
fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd < 0)
return -errno;
return btrfs_subvol_get_subtree_quota_fd(fd, subvol_id, ret);
}
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_qgroup_set_limit_fd(int fd, uint64_t qgroupid, uint64_t referenced_max) {
struct btrfs_ioctl_qgroup_limit_args args = {
.lim.max_rfer = referenced_max,
.lim.flags = BTRFS_QGROUP_LIMIT_MAX_RFER,
};
unsigned c;
int r;
assert(fd >= 0);
if (qgroupid == 0) {
r = btrfs_subvol_get_id_fd(fd, &qgroupid);
if (r < 0)
return r;
} else {
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (!r)
return -ENOTTY;
}
args.qgroupid = qgroupid;
for (c = 0;; c++) {
if (ioctl(fd, BTRFS_IOC_QGROUP_LIMIT, &args) < 0) {
if (errno == EBUSY && c < 10) {
(void) btrfs_quota_scan_wait(fd);
continue;
}
return -errno;
}
break;
}
return 0;
}
int btrfs_qgroup_set_limit(const char *path, uint64_t qgroupid, 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_qgroup_set_limit_fd(fd, qgroupid, referenced_max);
}
int btrfs_subvol_set_subtree_quota_limit_fd(int fd, uint64_t subvol_id, uint64_t referenced_max) {
uint64_t qgroupid;
int r;
assert(fd >= 0);
r = btrfs_subvol_find_subtree_qgroup(fd, subvol_id, &qgroupid);
if (r < 0)
return r;
return btrfs_qgroup_set_limit_fd(fd, qgroupid, referenced_max);
}
int btrfs_subvol_set_subtree_quota_limit(const char *path, uint64_t subvol_id, 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_subvol_set_subtree_quota_limit_fd(fd, subvol_id, 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;
/* In contrast to btrfs quota ioctls ftruncate() cannot make sense of "infinity" or file sizes > 2^31 */
if (!FILE_SIZE_VALID(new_size))
return -EINVAL;
/* 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);
}
int btrfs_qgroupid_make(uint64_t level, uint64_t id, uint64_t *ret) {
assert(ret);
if (level >= (UINT64_C(1) << (64 - BTRFS_QGROUP_LEVEL_SHIFT)))
return -EINVAL;
if (id >= (UINT64_C(1) << BTRFS_QGROUP_LEVEL_SHIFT))
return -EINVAL;
*ret = (level << BTRFS_QGROUP_LEVEL_SHIFT) | id;
return 0;
}
int btrfs_qgroupid_split(uint64_t qgroupid, uint64_t *level, uint64_t *id) {
assert(level || id);
if (level)
*level = qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT;
if (id)
*id = qgroupid & ((UINT64_C(1) << BTRFS_QGROUP_LEVEL_SHIFT) - 1);
return 0;
}
static int qgroup_create_or_destroy(int fd, bool b, uint64_t qgroupid) {
struct btrfs_ioctl_qgroup_create_args args = {
.create = b,
.qgroupid = qgroupid,
};
unsigned c;
int r;
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (r == 0)
return -ENOTTY;
for (c = 0;; c++) {
if (ioctl(fd, BTRFS_IOC_QGROUP_CREATE, &args) < 0) {
/* If quota is not enabled, we get EINVAL. Turn this into a recognizable error */
if (errno == EINVAL)
return -ENOPROTOOPT;
if (errno == EBUSY && c < 10) {
(void) btrfs_quota_scan_wait(fd);
continue;
}
return -errno;
}
break;
}
return 0;
}
int btrfs_qgroup_create(int fd, uint64_t qgroupid) {
return qgroup_create_or_destroy(fd, true, qgroupid);
}
int btrfs_qgroup_destroy(int fd, uint64_t qgroupid) {
return qgroup_create_or_destroy(fd, false, qgroupid);
}
int btrfs_qgroup_destroy_recursive(int fd, uint64_t qgroupid) {
_cleanup_free_ uint64_t *qgroups = NULL;
uint64_t subvol_id;
int i, n, r;
/* Destroys the specified qgroup, but unassigns it from all
* its parents first. Also, it recursively destroys all
* qgroups it is assgined to that have the same id part of the
* qgroupid as the specified group. */
r = btrfs_qgroupid_split(qgroupid, NULL, &subvol_id);
if (r < 0)
return r;
n = btrfs_qgroup_find_parents(fd, qgroupid, &qgroups);
if (n < 0)
return n;
for (i = 0; i < n; i++) {
uint64_t id;
r = btrfs_qgroupid_split(qgroups[i], NULL, &id);
if (r < 0)
return r;
r = btrfs_qgroup_unassign(fd, qgroupid, qgroups[i]);
if (r < 0)
return r;
if (id != subvol_id)
continue;
/* The parent qgroupid shares the same id part with
* us? If so, destroy it too. */
(void) btrfs_qgroup_destroy_recursive(fd, qgroups[i]);
}
return btrfs_qgroup_destroy(fd, qgroupid);
}
int btrfs_quota_scan_start(int fd) {
struct btrfs_ioctl_quota_rescan_args args = {};
assert(fd >= 0);
if (ioctl(fd, BTRFS_IOC_QUOTA_RESCAN, &args) < 0)
return -errno;
return 0;
}
int btrfs_quota_scan_wait(int fd) {
assert(fd >= 0);
if (ioctl(fd, BTRFS_IOC_QUOTA_RESCAN_WAIT) < 0)
return -errno;
return 0;
}
int btrfs_quota_scan_ongoing(int fd) {
struct btrfs_ioctl_quota_rescan_args args = {};
assert(fd >= 0);
if (ioctl(fd, BTRFS_IOC_QUOTA_RESCAN_STATUS, &args) < 0)
return -errno;
return !!args.flags;
}
static int qgroup_assign_or_unassign(int fd, bool b, uint64_t child, uint64_t parent) {
struct btrfs_ioctl_qgroup_assign_args args = {
.assign = b,
.src = child,
.dst = parent,
};
unsigned c;
int r;
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (r == 0)
return -ENOTTY;
for (c = 0;; c++) {
r = ioctl(fd, BTRFS_IOC_QGROUP_ASSIGN, &args);
if (r < 0) {
if (errno == EBUSY && c < 10) {
(void) btrfs_quota_scan_wait(fd);
continue;
}
return -errno;
}
if (r == 0)
return 0;
/* If the return value is > 0, we need to request a rescan */
(void) btrfs_quota_scan_start(fd);
return 1;
}
}
int btrfs_qgroup_assign(int fd, uint64_t child, uint64_t parent) {
return qgroup_assign_or_unassign(fd, true, child, parent);
}
int btrfs_qgroup_unassign(int fd, uint64_t child, uint64_t parent) {
return qgroup_assign_or_unassign(fd, false, child, parent);
}
static int subvol_remove_children(int fd, const char *subvolume, uint64_t subvol_id, BtrfsRemoveFlags 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 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;
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;
}
/* 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) {
(void) btrfs_qgroup_destroy_recursive(fd, subvol_id); /* for the leaf subvolumes, the qgroup id is identical to the subvol id */
return 0;
}
if (!(flags & BTRFS_REMOVE_RECURSIVE) || errno != ENOTEMPTY)
return -errno;
/* OK, the subvolume is not empty, let's look for child
* subvolumes, and remove them, first */
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
* directory of the subvolume. */
r = subvol_remove_children(subvol_fd, p, sh->objectid, flags);
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, flags);
}
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;
(void) btrfs_qgroup_destroy_recursive(fd, subvol_id);
return 0;
}
int btrfs_subvol_remove(const char *path, BtrfsRemoveFlags flags) {
_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, flags);
}
int btrfs_subvol_remove_fd(int fd, const char *subvolume, BtrfsRemoveFlags flags) {
return subvol_remove_children(fd, subvolume, 0, flags);
}
int btrfs_qgroup_copy_limits(int fd, uint64_t old_qgroupid, uint64_t new_qgroupid) {
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_LIMIT_KEY,
.key.max_type = BTRFS_QGROUP_LIMIT_KEY,
/* For our qgroup */
.key.min_offset = old_qgroupid,
.key.max_offset = old_qgroupid,
/* No restrictions on the other components */
.key.min_transid = 0,
.key.max_transid = (uint64_t) -1,
};
int r;
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (!r)
return -ENOTTY;
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) {
if (errno == ENOENT) /* quota tree missing: quota is not enabled, hence nothing to copy */
break;
return -errno;
}
if (args.key.nr_items <= 0)
break;
FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) {
const struct btrfs_qgroup_limit_item *qli = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh);
struct btrfs_ioctl_qgroup_limit_args qargs;
unsigned c;
/* 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->type != BTRFS_QGROUP_LIMIT_KEY)
continue;
if (sh->offset != old_qgroupid)
continue;
/* We found the entry, now copy things over. */
qargs = (struct btrfs_ioctl_qgroup_limit_args) {
.qgroupid = new_qgroupid,
.lim.max_rfer = le64toh(qli->max_rfer),
.lim.max_excl = le64toh(qli->max_excl),
.lim.rsv_rfer = le64toh(qli->rsv_rfer),
.lim.rsv_excl = le64toh(qli->rsv_excl),
.lim.flags = le64toh(qli->flags) & (BTRFS_QGROUP_LIMIT_MAX_RFER|
BTRFS_QGROUP_LIMIT_MAX_EXCL|
BTRFS_QGROUP_LIMIT_RSV_RFER|
BTRFS_QGROUP_LIMIT_RSV_EXCL),
};
for (c = 0;; c++) {
if (ioctl(fd, BTRFS_IOC_QGROUP_LIMIT, &qargs) < 0) {
if (errno == EBUSY && c < 10) {
(void) btrfs_quota_scan_wait(fd);
continue;
}
return -errno;
}
break;
}
return 1;
}
/* Increase search key by one, to read the next item, if we can. */
if (!btrfs_ioctl_search_args_inc(&args))
break;
}
return 0;
}
static int copy_quota_hierarchy(int fd, uint64_t old_subvol_id, uint64_t new_subvol_id) {
_cleanup_free_ uint64_t *old_qgroups = NULL, *old_parent_qgroups = NULL;
bool copy_from_parent = false, insert_intermediary_qgroup = false;
int n_old_qgroups, n_old_parent_qgroups, r, i;
uint64_t old_parent_id;
assert(fd >= 0);
/* Copies a reduced form of quota information from the old to
* the new subvolume. */
n_old_qgroups = btrfs_qgroup_find_parents(fd, old_subvol_id, &old_qgroups);
if (n_old_qgroups <= 0) /* Nothing to copy */
return n_old_qgroups;
r = btrfs_subvol_get_parent(fd, old_subvol_id, &old_parent_id);
if (r == -ENXIO)
/* We have no parent, hence nothing to copy. */
n_old_parent_qgroups = 0;
else if (r < 0)
return r;
else {
n_old_parent_qgroups = btrfs_qgroup_find_parents(fd, old_parent_id, &old_parent_qgroups);
if (n_old_parent_qgroups < 0)
return n_old_parent_qgroups;
}
for (i = 0; i < n_old_qgroups; i++) {
uint64_t id;
int j;
r = btrfs_qgroupid_split(old_qgroups[i], NULL, &id);
if (r < 0)
return r;
if (id == old_subvol_id) {
/* The old subvolume was member of a qgroup
* that had the same id, but a different level
* as it self. Let's set up something similar
* in the destination. */
insert_intermediary_qgroup = true;
break;
}
for (j = 0; j < n_old_parent_qgroups; j++)
if (old_parent_qgroups[j] == old_qgroups[i]) {
/* The old subvolume shared a common
* parent qgroup with its parent
* subvolume. Let's set up something
* similar in the destination. */
copy_from_parent = true;
}
}
if (!insert_intermediary_qgroup && !copy_from_parent)
return 0;
return btrfs_subvol_auto_qgroup_fd(fd, new_subvol_id, insert_intermediary_qgroup);
}
static int copy_subtree_quota_limits(int fd, uint64_t old_subvol, uint64_t new_subvol) {
uint64_t old_subtree_qgroup, new_subtree_qgroup;
bool changed;
int r;
/* First copy the leaf limits */
r = btrfs_qgroup_copy_limits(fd, old_subvol, new_subvol);
if (r < 0)
return r;
changed = r > 0;
/* Then, try to copy the subtree limits, if there are any. */
r = btrfs_subvol_find_subtree_qgroup(fd, old_subvol, &old_subtree_qgroup);
if (r < 0)
return r;
if (r == 0)
return changed;
r = btrfs_subvol_find_subtree_qgroup(fd, new_subvol, &new_subtree_qgroup);
if (r < 0)
return r;
if (r == 0)
return changed;
r = btrfs_qgroup_copy_limits(fd, old_subtree_qgroup, new_subtree_qgroup);
if (r != 0)
return r;
return changed;
}
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);
if (ioctl(new_fd, BTRFS_IOC_SNAP_CREATE_V2, &vol_args) < 0)
return -errno;
if (!(flags & BTRFS_SNAPSHOT_RECURSIVE) &&
!(flags & BTRFS_SNAPSHOT_QUOTA))
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;
if (flags & BTRFS_SNAPSHOT_QUOTA)
(void) copy_quota_hierarchy(new_fd, old_subvol_id, new_subvol_id);
if (!(flags & BTRFS_SNAPSHOT_RECURSIVE)) {
if (flags & BTRFS_SNAPSHOT_QUOTA)
(void) copy_subtree_quota_limits(new_fd, old_subvol_id, new_subvol_id);
return 0;
}
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
* time */
if (sh->offset != old_subvol_id)
continue;
/* Avoid running into loops if the new
* subvolume is below the old one. */
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
* 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);
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
* need to mark it writable
* temporarily, to put the subsnapshot
* into place. */
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
* subvolumes appear as empty directories. Remove
* them, so that we can create a new snapshot
* in their place */
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;
}
if (flags & BTRFS_SNAPSHOT_QUOTA)
(void) copy_subtree_quota_limits(new_fd, old_subvol_id, new_subvol_id);
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_fd(old_fd);
if (r < 0)
return r;
if (r == 0) {
bool plain_directory = false;
/* If the source isn't a proper subvolume, fail unless fallback is requested */
if (!(flags & BTRFS_SNAPSHOT_FALLBACK_COPY))
return -EISDIR;
r = btrfs_subvol_make(new_path);
if (r == -ENOTTY && (flags & BTRFS_SNAPSHOT_FALLBACK_DIRECTORY)) {
/* If the destination doesn't support subvolumes, then use a plain directory, if that's requested. */
if (mkdir(new_path, 0755) < 0)
return r;
plain_directory = true;
} else if (r < 0)
return r;
r = copy_directory_fd(old_fd, new_path, true);
if (r < 0)
goto fallback_fail;
if (flags & BTRFS_SNAPSHOT_READ_ONLY) {
if (plain_directory) {
/* Plain directories have no recursive read-only flag, but something pretty close to
* it: the IMMUTABLE bit. Let's use this here, if this is requested. */
if (flags & BTRFS_SNAPSHOT_FALLBACK_IMMUTABLE)
(void) chattr_path(new_path, FS_IMMUTABLE_FL, FS_IMMUTABLE_FL);
} else {
r = btrfs_subvol_set_read_only(new_path, true);
if (r < 0)
goto fallback_fail;
}
}
return 0;
fallback_fail:
(void) rm_rf(new_path, REMOVE_ROOT|REMOVE_PHYSICAL|REMOVE_SUBVOLUME);
return r;
}
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);
}
int btrfs_qgroup_find_parents(int fd, uint64_t qgroupid, uint64_t **ret) {
struct btrfs_ioctl_search_args args = {
/* Tree of quota items */
.key.tree_id = BTRFS_QUOTA_TREE_OBJECTID,
/* Look precisely for the quota relation items */
.key.min_type = BTRFS_QGROUP_RELATION_KEY,
.key.max_type = BTRFS_QGROUP_RELATION_KEY,
/* No restrictions on the other components */
.key.min_offset = 0,
.key.max_offset = (uint64_t) -1,
.key.min_transid = 0,
.key.max_transid = (uint64_t) -1,
};
_cleanup_free_ uint64_t *items = NULL;
size_t n_items = 0, n_allocated = 0;
int r;
assert(fd >= 0);
assert(ret);
if (qgroupid == 0) {
r = btrfs_subvol_get_id_fd(fd, &qgroupid);
if (r < 0)
return r;
} else {
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (!r)
return -ENOTTY;
}
args.key.min_objectid = args.key.max_objectid = qgroupid;
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) {
if (errno == ENOENT) /* quota tree missing: quota is disabled */
break;
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->type != BTRFS_QGROUP_RELATION_KEY)
continue;
if (sh->offset < sh->objectid)
continue;
if (sh->objectid != qgroupid)
continue;
if (!GREEDY_REALLOC(items, n_allocated, n_items+1))
return -ENOMEM;
items[n_items++] = sh->offset;
}
/* Increase search key by one, to read the next item, if we can. */
if (!btrfs_ioctl_search_args_inc(&args))
break;
}
if (n_items <= 0) {
*ret = NULL;
return 0;
}
*ret = items;
items = NULL;
return (int) n_items;
}
int btrfs_subvol_auto_qgroup_fd(int fd, uint64_t subvol_id, bool insert_intermediary_qgroup) {
_cleanup_free_ uint64_t *qgroups = NULL;
uint64_t parent_subvol;
bool changed = false;
int n = 0, r;
assert(fd >= 0);
/*
* Sets up the specified subvolume's qgroup automatically in
* one of two ways:
*
* If insert_intermediary_qgroup is false, the subvolume's
* leaf qgroup will be assigned to the same parent qgroups as
* the subvolume's parent subvolume.
*
* If insert_intermediary_qgroup is true a new intermediary
* higher-level qgroup is created, with a higher level number,
* but reusing the id of the subvolume. The level number is
* picked as one smaller than the lowest level qgroup the
* parent subvolume is a member of. If the parent subvolume's
* leaf qgroup is assigned to no higher-level qgroup a new
* qgroup of level 255 is created instead. Either way, the new
* qgroup is then assigned to the parent's higher-level
* qgroup, and the subvolume itself is assigned to it.
*
* If the subvolume is already assigned to a higher level
* qgroup, no operation is executed.
*
* Effectively this means: regardless if
* insert_intermediary_qgroup is true or not, after this
* function is invoked the subvolume will be accounted within
* the same qgroups as the parent. However, if it is true, it
* will also get its own higher-level qgroup, which may in
* turn be used by subvolumes created beneath this subvolume
* later on.
*
* This hence defines a simple default qgroup setup for
* subvolumes, as long as this function is invoked on each
* created subvolume: each subvolume is always accounting
* together with its immediate parents. Optionally, if
* insert_intermediary_qgroup is true, it will also get a
* qgroup that then includes all its own child subvolumes.
*/
if (subvol_id == 0) {
r = btrfs_is_subvol_fd(fd);
if (r < 0)
return r;
if (!r)
return -ENOTTY;
r = btrfs_subvol_get_id_fd(fd, &subvol_id);
if (r < 0)
return r;
}
n = btrfs_qgroup_find_parents(fd, subvol_id, &qgroups);
if (n < 0)
return n;
if (n > 0) /* already parent qgroups set up, let's bail */
return 0;
qgroups = mfree(qgroups);
r = btrfs_subvol_get_parent(fd, subvol_id, &parent_subvol);
if (r == -ENXIO)
/* No parent, hence no qgroup memberships */
n = 0;
else if (r < 0)
return r;
else {
n = btrfs_qgroup_find_parents(fd, parent_subvol, &qgroups);
if (n < 0)
return n;
}
if (insert_intermediary_qgroup) {
uint64_t lowest = 256, new_qgroupid;
bool created = false;
int i;
/* Determine the lowest qgroup that the parent
* subvolume is assigned to. */
for (i = 0; i < n; i++) {
uint64_t level;
r = btrfs_qgroupid_split(qgroups[i], &level, NULL);
if (r < 0)
return r;
if (level < lowest)
lowest = level;
}
if (lowest <= 1) /* There are no levels left we could use insert an intermediary qgroup at */
return -EBUSY;
r = btrfs_qgroupid_make(lowest - 1, subvol_id, &new_qgroupid);
if (r < 0)
return r;
/* Create the new intermediary group, unless it already exists */
r = btrfs_qgroup_create(fd, new_qgroupid);
if (r < 0 && r != -EEXIST)
return r;
if (r >= 0)
changed = created = true;
for (i = 0; i < n; i++) {
r = btrfs_qgroup_assign(fd, new_qgroupid, qgroups[i]);
if (r < 0 && r != -EEXIST) {
if (created)
(void) btrfs_qgroup_destroy_recursive(fd, new_qgroupid);
return r;
}
if (r >= 0)
changed = true;
}
r = btrfs_qgroup_assign(fd, subvol_id, new_qgroupid);
if (r < 0 && r != -EEXIST) {
if (created)
(void) btrfs_qgroup_destroy_recursive(fd, new_qgroupid);
return r;
}
if (r >= 0)
changed = true;
} else {
int i;
/* Assign our subvolume to all the same qgroups as the parent */
for (i = 0; i < n; i++) {
r = btrfs_qgroup_assign(fd, subvol_id, qgroups[i]);
if (r < 0 && r != -EEXIST)
return r;
if (r >= 0)
changed = true;
}
}
return changed;
}
int btrfs_subvol_auto_qgroup(const char *path, uint64_t subvol_id, bool create_intermediary_qgroup) {
_cleanup_close_ int fd = -1;
fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0)
return -errno;
return btrfs_subvol_auto_qgroup_fd(fd, subvol_id, create_intermediary_qgroup);
}
int btrfs_subvol_get_parent(int fd, uint64_t subvol_id, uint64_t *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_BACKREF_KEY,
.key.max_type = BTRFS_ROOT_BACKREF_KEY,
/* No restrictions on the other components */
.key.min_offset = 0,
.key.max_offset = (uint64_t) -1,
.key.min_transid = 0,
.key.max_transid = (uint64_t) -1,
};
int r;
assert(fd >= 0);
assert(ret);
if (subvol_id == 0) {
r = btrfs_subvol_get_id_fd(fd, &subvol_id);
if (r < 0)
return r;
} else {
r = btrfs_is_filesystem(fd);
if (r < 0)
return r;
if (!r)
return -ENOTTY;
}
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 negative_errno();
if (args.key.nr_items <= 0)
break;
FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) {
if (sh->type != BTRFS_ROOT_BACKREF_KEY)
continue;
if (sh->objectid != subvol_id)
continue;
*ret = sh->offset;
return 0;
}
}
return -ENXIO;
}
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