/*-*- 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" /* 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 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 * 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, 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 * 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 (!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, 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 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 * 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, 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 * 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; } 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); }