+
+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;
+ 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);
+}