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add systemd-clone tool
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‎meson.build‎

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@@ -291,6 +291,7 @@ conf.set_quoted('SYSTEMD_USERWORK_PATH', libexecdir / 'syst
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conf.set_quoted('SYSTEMD_MOUNTWORK_PATH', libexecdir / 'systemd-mountwork')
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conf.set_quoted('SYSTEMD_NSRESOURCEWORK_PATH', libexecdir / 'systemd-nsresourcework')
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conf.set_quoted('SYSTEMD_VERITYSETUP_PATH', libexecdir / 'systemd-veritysetup')
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conf.set_quoted('SYSTEMD_CLONE_PATH', bindir / 'systemd-clone')
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conf.set_quoted('SYSTEM_CONFIG_UNIT_DIR', pkgsysconfdir / 'system')
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conf.set_quoted('SYSTEM_DATA_UNIT_DIR', systemunitdir)
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conf.set_quoted('SYSTEM_ENV_GENERATOR_DIR', systemenvgeneratordir)
@@ -2351,6 +2352,7 @@ subdir('src/debug-generator')
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subdir('src/delta')
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subdir('src/detect-virt')
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subdir('src/dissect')
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subdir('src/clone')
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subdir('src/environment-d-generator')
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subdir('src/escape')
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subdir('src/factory-reset')

‎src/clone/clone-ioctl.c‎

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <fcntl.h>
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#include <linux/dm-ioctl.h>
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#include <sys/ioctl.h>
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#include <sys/stat.h>
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#include "clone-ioctl.h"
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#include "device-private.h"
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#include "fd-util.h"
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#include "log.h"
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#include "memory-util.h" /* memzero() */
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#include "sd-device.h"
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#include "stdio-util.h" /* xsprintf() */
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#include "string-util.h"
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static int get_size(const char *dev_path, uint64_t *ret_size) {
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_cleanup_(sd_device_unrefp) sd_device *dev = NULL;
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uint64_t size;
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int r;
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assert(dev_path);
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assert(ret_size);
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r = sd_device_new_from_devname(&dev, dev_path);
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if (r < 0)
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return log_error_errno(r, "Failed to create device from '%s': %m", dev_path);
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r = device_get_sysattr_u64(dev, "size", &size);
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if (r < 0)
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return log_error_errno(r, "Failed to get device size for '%s': %m", dev_path);
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/* sysfs 'size' is in 512-byte sectors */
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*ret_size = size * 512;
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return 0;
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}
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static int dm_ioctl_run(const char *name, uint32_t cmd, struct dm_ioctl *data, size_t data_size) {
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_cleanup_close_ int fd = -EBADF;
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struct dm_ioctl *dm = data;
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assert(name);
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assert(data);
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assert(data_size >= sizeof(struct dm_ioctl));
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dm->version[0] = DM_VERSION_MAJOR;
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dm->version[1] = DM_VERSION_MINOR;
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dm->version[2] = DM_VERSION_PATCHLEVEL;
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dm->data_size = data_size;
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assert(strlen(name) < sizeof_field(struct dm_ioctl, name));
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strncpy_exact(dm->name, name, sizeof(dm->name));
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fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC);
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if (fd < 0)
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return log_error_errno(errno, "Failed to open /dev/mapper/control: %m");
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if (ioctl(fd, cmd, dm) < 0)
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return log_error_errno(errno, "DM ioctl failed: %m");
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return 0;
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}
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static int dm_clone_create(const char *name) {
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assert(name);
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struct dm_ioctl dm = {};
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return dm_ioctl_run(name, DM_DEV_CREATE, &dm, sizeof(struct dm_ioctl));
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}
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static int dm_clone_load_table(const char *name, uint64_t size_sectors, const char *target_params) {
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char *params_buf;
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size_t params_len, dm_size;
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struct dm_ioctl *dm;
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struct dm_target_spec *tgt;
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assert(name);
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assert(target_params);
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params_len = strlen(target_params) + 1;
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dm_size = sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec) + params_len;
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dm = alloca0(dm_size);
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dm->data_start = sizeof(struct dm_ioctl);
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dm->target_count = 1;
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tgt = (struct dm_target_spec *) ((uint8_t *) dm + dm->data_start);
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tgt->sector_start = 0;
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tgt->length = size_sectors;
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strncpy(tgt->target_type, "clone", sizeof(tgt->target_type));
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tgt->next = 0;
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params_buf = (char *) tgt + sizeof(struct dm_target_spec);
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strcpy(params_buf, target_params);
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tgt->status = 0;
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return dm_ioctl_run(name, DM_TABLE_LOAD, dm, dm_size);
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}
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static int dm_clone_activate(const char *name) {
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assert(name);
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struct dm_ioctl dm = {};
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return dm_ioctl_run(name, DM_DEV_SUSPEND, &dm, sizeof(struct dm_ioctl));
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}
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int dm_clone_create_device(
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const char *name,
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const char *source_dev,
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const char *dest_dev,
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const char *metadata_dev) {
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uint64_t src_dev_size_sectors, src_dev_size;
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char target_params[256];
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int r;
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assert(name);
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assert(source_dev);
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assert(dest_dev);
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assert(metadata_dev);
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r = get_size(source_dev, &src_dev_size);
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if (r < 0)
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return r;
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src_dev_size_sectors = src_dev_size / 512;
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/* dm-clone target params: <metadata_dev> <dest_dev> <source_dev> <region_size> <hydration_threshold> [options]
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* 8 = region size in sectors (4KB regions with 512-byte sectors)
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* 1 = hydration threshold (regions to hydrate per batch)
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* no_hydration = don't start automatic background hydration */
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xsprintf(target_params, "%s %s %s 8 1 no_hydration", metadata_dev, dest_dev, source_dev);
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r = dm_clone_create(name);
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if (r < 0)
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return r;
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r = dm_clone_load_table(name, src_dev_size_sectors, target_params);
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if (r < 0)
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return r;
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r = dm_clone_activate(name);
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if (r < 0)
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return r;
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return 0;
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}
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int dm_clone_send_message(const char *name, const char *message) {
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struct dm_ioctl *dm;
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struct dm_target_msg *msg;
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size_t dm_size, msg_len;
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assert(name);
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assert(message);
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msg_len = strlen(message) + 1;
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dm_size = sizeof(struct dm_ioctl) + sizeof(struct dm_target_msg) + msg_len;
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dm = alloca0(dm_size);
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dm->data_start = sizeof(struct dm_ioctl);
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msg = (struct dm_target_msg *) ((char *) dm + dm->data_start);
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strcpy(msg->message, message);
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return dm_ioctl_run(name, DM_TARGET_MSG, dm, dm_size);
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}

‎src/clone/clone-ioctl.h‎

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include <inttypes.h>
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int dm_clone_create_device(
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const char *name,
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const char *source_dev,
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const char *dest_dev,
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const char *metadata_dev);
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int dm_clone_send_message(const char *name, const char *message);
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‎src/clone/clone.c‎

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <getopt.h>
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#include <stdio.h>
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#include <sys/stat.h>
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#include <unistd.h> /* access */
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#include "alloc-util.h"
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#include "argv-util.h"
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#include "build.h"
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#include "clone-ioctl.h"
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#include "log.h"
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#include "main-func.h"
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#include "pretty-print.h"
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#include "verbs.h"
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#include "path-util.h" /* path_join */
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#include "time-util.h" /* USEC_PER_SEC */
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#include "udev-util.h" /* device_wait_for_devlink */
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/* dm-clone device creation workflow:
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* 1. Create the dm-clone device
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* 2. Enable background hydration
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* 3. (Optional) Replace with linear mapping to finalize */
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static int clone_device(const char *clone_name, const char *source_dev, const char *dest_dev,
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const char *metadata_dev) {
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_cleanup_free_ char *clone_dev_path = NULL;
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int r;
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assert(clone_name);
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assert(source_dev);
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assert(dest_dev);
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assert(metadata_dev);
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/* create clone device path to check if clone device already exists */
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clone_dev_path = path_join("/dev/mapper", clone_name);
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if (!clone_dev_path)
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return log_oom();
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if (access(clone_dev_path, F_OK) >= 0)
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return log_error_errno(SYNTHETIC_ERRNO(EEXIST), "Device '%s' already exists.", clone_dev_path);
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r = dm_clone_create_device(clone_name, source_dev, dest_dev, metadata_dev);
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if (r < 0)
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return log_error_errno(r, "Failed to create dm-clone device: %m");
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/* Wait for udev to create /dev/mapper/<name> */
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r = device_wait_for_devlink(clone_dev_path, "block", 10 * USEC_PER_SEC, NULL);
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if (r < 0)
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return log_error_errno(r, "Failed to wait for device %s: %m", clone_dev_path);
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r = dm_clone_send_message(clone_name, "enable_hydration");
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if (r < 0)
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return log_error_errno(r, "Failed to send dm message: %m");
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return 0;
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}
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/* Arguments: systemd-clone add NAME SOURCE-DEVICE DST_DEVICE META-DEVICE [OPTIONS] */
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static int verb_add(int argc, char *argv[], void *userdata) {
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int r;
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assert(argc >= 5 && argc <= 6);
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const char *name = ASSERT_PTR(argv[1]),
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*src_dev = ASSERT_PTR(argv[2]),
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*dst_dev = ASSERT_PTR(argv[3]),
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*meta_dev = ASSERT_PTR(argv[4]);
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log_debug("%s %s %s %s %s opts=%s ", __func__,
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name, src_dev, dst_dev, meta_dev, "");
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r = clone_device(name, src_dev, dst_dev, meta_dev);
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if (r < 0)
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return r;
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return 0;
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}
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static int verb_remove(int argc, char *argv[], void *userdata) {
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return 0;
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}
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static int help(void) {
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_cleanup_free_ char *link = NULL;
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int r;
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r = terminal_urlify_man("systemd-clone", "8", &link);
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if (r < 0)
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return log_oom();
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printf("%1$s add NAME SOURCE-DEVICE DST-DEVICE META-DEVICE [OPTIONS] \n"
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"%1$s remove VOLUME\n\n"
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"%2$sAdd or remove a dm clone device.%3$s\n\n"
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" -h --help Show this help\n"
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" --version Show package version\n"
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"\nSee the %4$s for details.\n",
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program_invocation_short_name,
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ansi_highlight(),
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ansi_normal(),
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link);
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return 0;
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}
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static int parse_argv(int argc, char *argv[]) {
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enum {
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ARG_VERSION = 0x100,
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};
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static const struct option options[] = {
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{ "help", no_argument, NULL, 'h' },
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{ "version", no_argument, NULL, ARG_VERSION },
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{}
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};
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int c;
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assert(argc >= 0);
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assert(argv);
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if (argv_looks_like_help(argc, argv))
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return help();
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while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
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switch (c) {
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case 'h':
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return help();
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case ARG_VERSION:
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return version();
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case '?':
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return -EINVAL;
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default:
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assert_not_reached();
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}
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return 1;
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}
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static int run(int argc, char *argv[]) {
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int r;
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log_setup();
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umask(0022);
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r = parse_argv(argc, argv);
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if (r <= 0)
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return r;
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static const Verb verbs[] = {
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{ "add", 5, 6, 0, verb_add },
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{ "remove", 1, 1, 0, verb_remove },
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{}
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};
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return dispatch_verb(argc, argv, verbs, NULL);
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}
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DEFINE_MAIN_FUNCTION(run);

‎src/clone/meson.build‎

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# SPDX-License-Identifier: LGPL-2.1-or-later
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systemd_clone_sources = files(
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'clone-ioctl.c',
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'clone.c',
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)
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executables += [
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executable_template + {
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'name' : 'systemd-clone',
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'public' : true,
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'sources' : systemd_clone_sources,
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},
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]

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