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-rw-r--r--src/basic/btrfs-util.c1152
1 files changed, 1152 insertions, 0 deletions
diff --git a/src/basic/btrfs-util.c b/src/basic/btrfs-util.c
new file mode 100644
index 0000000000..49528dbf01
--- /dev/null
+++ b/src/basic/btrfs-util.c
@@ -0,0 +1,1152 @@
+/*-*- 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;
+}
+
+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 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,
+ };
+ int r;
+ _cleanup_close_ int subvolume_fd = -1;
+
+ 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 (subvol_id == 0) {
+ r = btrfs_subvol_get_id_fd(old_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(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;
+ 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(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 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);
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-18 07:17:22 +0000