}
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_MAX,
- };
-
struct btrfs_ioctl_vol_args vol_args = {};
_cleanup_close_ int subvol_fd = -EBADF;
bool made_writable = false;
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;
+ /* OK, the subvolume is not empty, let's look for child subvolumes, and remove them, first.
+ * BTRFS_IOC_GET_SUBVOL_ROOTREF and BTRFS_IOC_INO_LOOKUP_USER (kernel 4.18+) enumerate child
+ * subvolumes without requiring CAP_SYS_ADMIN in the initial user namespace, unlike the older
+ * BTRFS_IOC_TREE_SEARCH ioctl. */
- while (btrfs_ioctl_search_args_compare(&args) <= 0) {
- struct btrfs_ioctl_search_header sh;
- const void *body;
+ struct btrfs_ioctl_get_subvol_rootref_args rootref_args = {};
- args.key.nr_items = 256;
- if (ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args) < 0)
+ for (;;) {
+ /* BTRFS_IOC_GET_SUBVOL_ROOTREF returns up to BTRFS_MAX_ROOTREF_BUFFER_NUM entries per
+ * call. If more are available, it returns -EOVERFLOW with num_items filled in and
+ * min_treeid advanced so we can resume on the next iteration. */
+ int ioctl_ret = ioctl(subvol_fd, BTRFS_IOC_GET_SUBVOL_ROOTREF, &rootref_args);
+ if (ioctl_ret < 0 && errno != EOVERFLOW)
return -errno;
- if (args.key.nr_items <= 0)
- break;
-
- FOREACH_BTRFS_IOCTL_SEARCH_HEADER(sh, body, args) {
- _cleanup_free_ char *p = NULL;
-
- btrfs_ioctl_search_args_set(&args, &sh);
-
- if (sh.type != BTRFS_ROOT_BACKREF_KEY)
- continue;
- if (sh.offset != subvol_id)
- continue;
-
- const struct btrfs_root_ref *ref = body;
- p = memdup_suffix0((char*) ref + sizeof(struct btrfs_root_ref), le64toh(ref->name_len));
- if (!p)
- return -ENOMEM;
+ for (uint8_t i = 0; i < rootref_args.num_items; i++) {
+ uint64_t child_subvol_id = rootref_args.rootref[i].treeid;
- struct btrfs_ioctl_ino_lookup_args ino_args = {
- .treeid = subvol_id,
- .objectid = htole64(ref->dirid),
+ struct btrfs_ioctl_ino_lookup_user_args lookup_args = {
+ .dirid = rootref_args.rootref[i].dirid,
+ .treeid = child_subvol_id,
};
-
- if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0)
+ if (ioctl(subvol_fd, BTRFS_IOC_INO_LOOKUP_USER, &lookup_args) < 0)
return -errno;
if (!made_writable) {
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);
+ if (isempty(lookup_args.path))
+ /* Subvolume is in the top-level directory of the subvolume. */
+ r = subvol_remove_children(subvol_fd, lookup_args.name, child_subvol_id, flags);
else {
_cleanup_close_ int child_fd = -EBADF;
- /* Subvolume is somewhere further down,
- * hence we need to open the
+ /* 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|O_NOFOLLOW);
+ child_fd = openat(subvol_fd, lookup_args.path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW);
if (child_fd < 0)
return -errno;
- r = subvol_remove_children(child_fd, p, sh.objectid, flags);
+ r = subvol_remove_children(child_fd, lookup_args.name, child_subvol_id, 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))
+ if (ioctl_ret >= 0)
break;
}
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_MAX,
- };
-
struct btrfs_ioctl_vol_args_v2 vol_args = {
.flags = flags & BTRFS_SNAPSHOT_READ_ONLY ? BTRFS_SUBVOL_RDONLY : 0,
.fd = old_fd,
return flags & BTRFS_SNAPSHOT_LOCK_BSD ? TAKE_FD(subvolume_fd) : 0;
}
- args.key.min_offset = args.key.max_offset = old_subvol_id;
+ /* Enumerate child subvolumes via BTRFS_IOC_GET_SUBVOL_ROOTREF + BTRFS_IOC_INO_LOOKUP_USER
+ * (kernel 4.18+), neither of which requires CAP_SYS_ADMIN, unlike BTRFS_IOC_TREE_SEARCH. */
- while (btrfs_ioctl_search_args_compare(&args) <= 0) {
- struct btrfs_ioctl_search_header sh;
- const void *body;
+ struct btrfs_ioctl_get_subvol_rootref_args rootref_args = {};
- args.key.nr_items = 256;
- if (ioctl(old_fd, BTRFS_IOC_TREE_SEARCH, &args) < 0)
+ for (;;) {
+ /* BTRFS_IOC_GET_SUBVOL_ROOTREF returns up to BTRFS_MAX_ROOTREF_BUFFER_NUM entries per
+ * call. If more are available, it returns -EOVERFLOW with num_items filled in and
+ * min_treeid advanced so we can resume on the next iteration. */
+ int ioctl_ret = ioctl(old_fd, BTRFS_IOC_GET_SUBVOL_ROOTREF, &rootref_args);
+ if (ioctl_ret < 0 && errno != EOVERFLOW)
return -errno;
- if (args.key.nr_items <= 0)
- break;
-
- FOREACH_BTRFS_IOCTL_SEARCH_HEADER(sh, body, args) {
- _cleanup_free_ char *p = NULL, *c = NULL, *np = NULL;
+ for (uint8_t i = 0; i < rootref_args.num_items; i++) {
+ _cleanup_free_ char *c = NULL, *np = NULL;
_cleanup_close_ int old_child_fd = -EBADF, new_child_fd = -EBADF;
-
- 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;
+ uint64_t child_subvol_id = rootref_args.rootref[i].treeid;
/* Avoid running into loops if the new subvolume is below the old one. */
- if (sh.objectid == new_subvol_id)
+ if (child_subvol_id == new_subvol_id)
continue;
- const struct btrfs_root_ref *ref = body;
- p = memdup_suffix0((char*) ref + sizeof(struct btrfs_root_ref), le64toh(ref->name_len));
- if (!p)
- return -ENOMEM;
-
- struct btrfs_ioctl_ino_lookup_args ino_args = {
- .treeid = old_subvol_id,
- .objectid = htole64(ref->dirid),
+ struct btrfs_ioctl_ino_lookup_user_args lookup_args = {
+ .dirid = rootref_args.rootref[i].dirid,
+ .treeid = child_subvol_id,
};
-
- if (ioctl(old_fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0)
+ if (ioctl(old_fd, BTRFS_IOC_INO_LOOKUP_USER, &lookup_args) < 0)
return -errno;
- c = path_join(ino_args.name, p);
+ c = path_join(lookup_args.path, lookup_args.name);
if (!c)
return -ENOMEM;
if (old_child_fd < 0)
return -errno;
- np = path_join(subvolume, ino_args.name);
+ np = path_join(subvolume, lookup_args.path);
if (!np)
return -ENOMEM;
/* 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) {
+ if (unlinkat(new_child_fd, lookup_args.name, AT_REMOVEDIR) < 0) {
int k = -errno;
if (flags & BTRFS_SNAPSHOT_READ_ONLY)
return k;
}
- r = subvol_snapshot_children(old_child_fd, new_child_fd, p, sh.objectid,
+ r = subvol_snapshot_children(old_child_fd, new_child_fd, lookup_args.name, child_subvol_id,
flags & ~(BTRFS_SNAPSHOT_FALLBACK_COPY|BTRFS_SNAPSHOT_LOCK_BSD));
/* Restore the readonly flag */
return r;
}
- /* Increase search key by one, to read the next item, if we can. */
- if (!btrfs_ioctl_search_args_inc(&args))
+ if (ioctl_ret >= 0)
break;
}
projects / thirdparty / systemd.git / commitdiff
