Adding upstream version 252.22.upstream/252.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 1695 insertions, 0 deletions

diff --git a/src/shutdown/meson.build b/src/shutdown/meson.build
new file mode 100644
index 0000000..0bd09fd
--- /dev/null
+++ b/src/shutdown/meson.build
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+systemd_shutdown_sources = files(
+        'shutdown.c',
+        'umount.c',
+        'umount.h',
+)
+
+tests += [
+        [files('test-umount.c',
+               'umount.c',
+               'umount.h'),
+         [],
+         [libmount]],
+]
diff --git a/src/shutdown/shutdown.c b/src/shutdown/shutdown.c
new file mode 100644
index 0000000..f9c798a
--- /dev/null
+++ b/src/shutdown/shutdown.c
@@ -0,0 +1,645 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2010 ProFUSION embedded systems
+***/
+
+#include <errno.h>
+#include <getopt.h>
+#include <linux/reboot.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <sys/reboot.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "async.h"
+#include "binfmt-util.h"
+#include "cgroup-setup.h"
+#include "cgroup-util.h"
+#include "def.h"
+#include "errno-util.h"
+#include "exec-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "killall.h"
+#include "log.h"
+#include "parse-util.h"
+#include "process-util.h"
+#include "reboot-util.h"
+#include "rlimit-util.h"
+#include "signal-util.h"
+#include "string-util.h"
+#include "switch-root.h"
+#include "sysctl-util.h"
+#include "terminal-util.h"
+#include "umount.h"
+#include "util.h"
+#include "virt.h"
+#include "watchdog.h"
+
+#define SYNC_PROGRESS_ATTEMPTS 3
+#define SYNC_TIMEOUT_USEC (10*USEC_PER_SEC)
+
+static char* arg_verb;
+static uint8_t arg_exit_code;
+static usec_t arg_timeout = DEFAULT_TIMEOUT_USEC;
+
+static int parse_argv(int argc, char *argv[]) {
+        enum {
+                ARG_LOG_LEVEL = 0x100,
+                ARG_LOG_TARGET,
+                ARG_LOG_COLOR,
+                ARG_LOG_LOCATION,
+                ARG_LOG_TIME,
+                ARG_EXIT_CODE,
+                ARG_TIMEOUT,
+        };
+
+        static const struct option options[] = {
+                { "log-level",     required_argument, NULL, ARG_LOG_LEVEL    },
+                { "log-target",    required_argument, NULL, ARG_LOG_TARGET   },
+                { "log-color",     optional_argument, NULL, ARG_LOG_COLOR    },
+                { "log-location",  optional_argument, NULL, ARG_LOG_LOCATION },
+                { "log-time",      optional_argument, NULL, ARG_LOG_TIME     },
+                { "exit-code",     required_argument, NULL, ARG_EXIT_CODE    },
+                { "timeout",       required_argument, NULL, ARG_TIMEOUT      },
+                {}
+        };
+
+        int c, r;
+
+        assert(argc >= 1);
+        assert(argv);
+
+        /* Resetting to 0 forces the invocation of an internal initialization routine of getopt_long()
+         * that checks for GNU extensions in optstring ('-' or '+' at the beginning). */
+        optind = 0;
+
+        /* "-" prevents getopt from permuting argv[] and moving the verb away
+         * from argv[1]. Our interface to initrd promises it'll be there. */
+        while ((c = getopt_long(argc, argv, "-", options, NULL)) >= 0)
+                switch (c) {
+
+                case ARG_LOG_LEVEL:
+                        r = log_set_max_level_from_string(optarg);
+                        if (r < 0)
+                                log_error_errno(r, "Failed to parse log level %s, ignoring: %m", optarg);
+
+                        break;
+
+                case ARG_LOG_TARGET:
+                        r = log_set_target_from_string(optarg);
+                        if (r < 0)
+                                log_error_errno(r, "Failed to parse log target %s, ignoring: %m", optarg);
+
+                        break;
+
+                case ARG_LOG_COLOR:
+
+                        if (optarg) {
+                                r = log_show_color_from_string(optarg);
+                                if (r < 0)
+                                        log_error_errno(r, "Failed to parse log color setting %s, ignoring: %m", optarg);
+                        } else
+                                log_show_color(true);
+
+                        break;
+
+                case ARG_LOG_LOCATION:
+                        if (optarg) {
+                                r = log_show_location_from_string(optarg);
+                                if (r < 0)
+                                        log_error_errno(r, "Failed to parse log location setting %s, ignoring: %m", optarg);
+                        } else
+                                log_show_location(true);
+
+                        break;
+
+                case ARG_LOG_TIME:
+
+                        if (optarg) {
+                                r = log_show_time_from_string(optarg);
+                                if (r < 0)
+                                        log_error_errno(r, "Failed to parse log time setting %s, ignoring: %m", optarg);
+                        } else
+                                log_show_time(true);
+
+                        break;
+
+                case ARG_EXIT_CODE:
+                        r = safe_atou8(optarg, &arg_exit_code);
+                        if (r < 0)
+                                log_error_errno(r, "Failed to parse exit code %s, ignoring: %m", optarg);
+
+                        break;
+
+                case ARG_TIMEOUT:
+                        r = parse_sec(optarg, &arg_timeout);
+                        if (r < 0)
+                                log_error_errno(r, "Failed to parse shutdown timeout %s, ignoring: %m", optarg);
+
+                        break;
+
+                case '\001':
+                        if (!arg_verb)
+                                arg_verb = optarg;
+                        else
+                                log_error("Excess arguments, ignoring");
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached();
+                }
+
+        if (!arg_verb)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "Verb argument missing.");
+
+        return 0;
+}
+
+static int switch_root_initramfs(void) {
+        if (mount("/run/initramfs", "/run/initramfs", NULL, MS_BIND, NULL) < 0)
+                return log_error_errno(errno, "Failed to mount bind /run/initramfs on /run/initramfs: %m");
+
+        if (mount(NULL, "/run/initramfs", NULL, MS_PRIVATE, NULL) < 0)
+                return log_error_errno(errno, "Failed to make /run/initramfs private mount: %m");
+
+        /* switch_root with MS_BIND, because there might still be processes lurking around, which have open file descriptors.
+         * /run/initramfs/shutdown will take care of these.
+         * Also do not detach the old root, because /run/initramfs/shutdown needs to access it.
+         */
+        return switch_root("/run/initramfs", "/oldroot", false, MS_BIND);
+}
+
+/* Read the following fields from /proc/meminfo:
+ *
+ *  NFS_Unstable
+ *  Writeback
+ *  Dirty
+ *
+ * Return true if the sum of these fields is greater than the previous
+ * value input. For all other issues, report the failure and indicate that
+ * the sync is not making progress.
+ */
+static int sync_making_progress(unsigned long long *prev_dirty) {
+        _cleanup_fclose_ FILE *f = NULL;
+        unsigned long long val = 0;
+        int ret;
+
+        f = fopen("/proc/meminfo", "re");
+        if (!f)
+                return log_warning_errno(errno, "Failed to open /proc/meminfo: %m");
+
+        for (;;) {
+                _cleanup_free_ char *line = NULL;
+                unsigned long long ull = 0;
+                int q;
+
+                q = read_line(f, LONG_LINE_MAX, &line);
+                if (q < 0)
+                        return log_warning_errno(q, "Failed to parse /proc/meminfo: %m");
+                if (q == 0)
+                        break;
+
+                if (!first_word(line, "NFS_Unstable:") && !first_word(line, "Writeback:") && !first_word(line, "Dirty:"))
+                        continue;
+
+                errno = 0;
+                if (sscanf(line, "%*s %llu %*s", &ull) != 1) {
+                        if (errno != 0)
+                                log_warning_errno(errno, "Failed to parse /proc/meminfo: %m");
+                        else
+                                log_warning("Failed to parse /proc/meminfo");
+
+                        return false;
+                }
+
+                val += ull;
+        }
+
+        ret = *prev_dirty > val;
+        *prev_dirty = val;
+        return ret;
+}
+
+static void sync_with_progress(void) {
+        unsigned long long dirty = ULLONG_MAX;
+        unsigned checks;
+        pid_t pid;
+        int r;
+
+        BLOCK_SIGNALS(SIGCHLD);
+
+        /* Due to the possibility of the sync operation hanging, we fork a child process and monitor
+         * the progress. If the timeout lapses, the assumption is that the particular sync stalled. */
+
+        r = asynchronous_sync(&pid);
+        if (r < 0) {
+                log_error_errno(r, "Failed to fork sync(): %m");
+                return;
+        }
+
+        log_info("Syncing filesystems and block devices.");
+
+        /* Start monitoring the sync operation. If more than
+         * SYNC_PROGRESS_ATTEMPTS lapse without progress being made,
+         * we assume that the sync is stalled */
+        for (checks = 0; checks < SYNC_PROGRESS_ATTEMPTS; checks++) {
+                r = wait_for_terminate_with_timeout(pid, SYNC_TIMEOUT_USEC);
+                if (r == 0)
+                        /* Sync finished without error.
+                         * (The sync itself does not return an error code) */
+                        return;
+                else if (r == -ETIMEDOUT) {
+                        /* Reset the check counter if the "Dirty" value is
+                         * decreasing */
+                        if (sync_making_progress(&dirty) > 0)
+                                checks = 0;
+                } else {
+                        log_error_errno(r, "Failed to sync filesystems and block devices: %m");
+                        return;
+                }
+        }
+
+        /* Only reached in the event of a timeout. We should issue a kill
+         * to the stray process. */
+        log_error("Syncing filesystems and block devices - timed out, issuing SIGKILL to PID "PID_FMT".", pid);
+        (void) kill(pid, SIGKILL);
+}
+
+static int read_current_sysctl_printk_log_level(void) {
+        _cleanup_free_ char *sysctl_printk_vals = NULL, *sysctl_printk_curr = NULL;
+        int current_lvl;
+        const char *p;
+        int r;
+
+        r = sysctl_read("kernel/printk", &sysctl_printk_vals);
+        if (r < 0)
+                return log_debug_errno(r, "Cannot read sysctl kernel.printk: %m");
+
+        p = sysctl_printk_vals;
+        r = extract_first_word(&p, &sysctl_printk_curr, NULL, 0);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to split out kernel printk priority: %m");
+        if (r == 0)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Short read while reading kernel.printk sysctl");
+
+        r = safe_atoi(sysctl_printk_curr, &current_lvl);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to parse kernel.printk sysctl: %s", sysctl_printk_vals);
+
+        return current_lvl;
+}
+
+static void bump_sysctl_printk_log_level(int min_level) {
+        int current_lvl, r;
+
+        /* Set the logging level to be able to see messages with log level smaller or equal to min_level */
+
+        current_lvl = read_current_sysctl_printk_log_level();
+        if (current_lvl < 0 || current_lvl >= min_level + 1)
+                return;
+
+        r = sysctl_writef("kernel/printk", "%i", min_level + 1);
+        if (r < 0)
+                log_debug_errno(r, "Failed to bump kernel.printk to %i: %m", min_level + 1);
+}
+
+static void init_watchdog(void) {
+        const char *s;
+        int r;
+
+        s = getenv("WATCHDOG_DEVICE");
+        if (s) {
+                r = watchdog_set_device(s);
+                if (r < 0)
+                        log_warning_errno(r, "Failed to set watchdog device to %s, ignoring: %m", s);
+        }
+
+        s = getenv("WATCHDOG_USEC");
+        if (s) {
+                usec_t usec;
+
+                r = safe_atou64(s, &usec);
+                if (r < 0)
+                        log_warning_errno(r, "Failed to parse watchdog timeout '%s', ignoring: %m", s);
+                else
+                        (void) watchdog_setup(usec);
+        }
+}
+
+int main(int argc, char *argv[]) {
+        static const char* const dirs[] = {
+                SYSTEM_SHUTDOWN_PATH,
+                NULL
+        };
+        _cleanup_free_ char *cgroup = NULL;
+        char *arguments[3];
+        int cmd, r;
+
+        /* The log target defaults to console, but the original systemd process will pass its log target in through a
+         * command line argument, which will override this default. Also, ensure we'll never log to the journal or
+         * syslog, as these logging daemons are either already dead or will die very soon. */
+
+        log_set_target(LOG_TARGET_CONSOLE);
+        log_set_prohibit_ipc(true);
+        log_parse_environment();
+
+        if (getpid_cached() == 1)
+                log_set_always_reopen_console(true);
+
+        r = parse_argv(argc, argv);
+        if (r < 0)
+                goto error;
+
+        log_open();
+
+        umask(0022);
+
+        if (getpid_cached() != 1) {
+                r = log_error_errno(SYNTHETIC_ERRNO(EPERM), "Not executed by init (PID 1).");
+                goto error;
+        }
+
+        if (streq(arg_verb, "reboot"))
+                cmd = RB_AUTOBOOT;
+        else if (streq(arg_verb, "poweroff"))
+                cmd = RB_POWER_OFF;
+        else if (streq(arg_verb, "halt"))
+                cmd = RB_HALT_SYSTEM;
+        else if (streq(arg_verb, "kexec"))
+                cmd = LINUX_REBOOT_CMD_KEXEC;
+        else if (streq(arg_verb, "exit"))
+                cmd = 0; /* ignored, just checking that arg_verb is valid */
+        else {
+                r = log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Unknown action '%s'.", arg_verb);
+                goto error;
+        }
+
+        (void) cg_get_root_path(&cgroup);
+        bool in_container = detect_container() > 0;
+
+        /* If the logging messages are going to KMSG, and if we are not running from a container, then try to
+         * update the sysctl kernel.printk current value in order to see "info" messages; This current log
+         * level is not updated if already big enough.
+         */
+        if (!in_container &&
+            IN_SET(log_get_target(),
+                   LOG_TARGET_AUTO,
+                   LOG_TARGET_JOURNAL_OR_KMSG,
+                   LOG_TARGET_SYSLOG_OR_KMSG,
+                   LOG_TARGET_KMSG))
+                bump_sysctl_printk_log_level(LOG_WARNING);
+
+        init_watchdog();
+
+        /* Lock us into memory */
+        (void) mlockall(MCL_CURRENT|MCL_FUTURE);
+
+        /* Synchronize everything that is not written to disk yet at this point already. This is a good idea so that
+         * slow IO is processed here already and the final process killing spree is not impacted by processes
+         * desperately trying to sync IO to disk within their timeout. Do not remove this sync, data corruption will
+         * result. */
+        if (!in_container)
+                sync_with_progress();
+
+        disable_coredumps();
+        disable_binfmt();
+
+        log_info("Sending SIGTERM to remaining processes...");
+        broadcast_signal(SIGTERM, true, true, arg_timeout);
+
+        log_info("Sending SIGKILL to remaining processes...");
+        broadcast_signal(SIGKILL, true, false, arg_timeout);
+
+        bool need_umount = !in_container, need_swapoff = !in_container, need_loop_detach = !in_container,
+             need_dm_detach = !in_container, need_md_detach = !in_container, can_initrd, last_try = false;
+        can_initrd = !in_container && !in_initrd() && access("/run/initramfs/shutdown", X_OK) == 0;
+
+        /* Unmount all mountpoints, swaps, and loopback devices */
+        for (;;) {
+                bool changed = false;
+
+                (void) watchdog_ping();
+
+                /* Let's trim the cgroup tree on each iteration so that we leave an empty cgroup tree around,
+                 * so that container managers get a nice notify event when we are down */
+                if (cgroup)
+                        (void) cg_trim(SYSTEMD_CGROUP_CONTROLLER, cgroup, false);
+
+                if (need_umount) {
+                        log_info("Unmounting file systems.");
+                        r = umount_all(&changed, last_try);
+                        if (r == 0) {
+                                need_umount = false;
+                                log_info("All filesystems unmounted.");
+                        } else if (r > 0)
+                                log_info("Not all file systems unmounted, %d left.", r);
+                        else
+                                log_error_errno(r, "Failed to unmount file systems: %m");
+                }
+
+                if (need_swapoff) {
+                        log_info("Deactivating swaps.");
+                        r = swapoff_all(&changed);
+                        if (r == 0) {
+                                need_swapoff = false;
+                                log_info("All swaps deactivated.");
+                        } else if (r > 0)
+                                log_info("Not all swaps deactivated, %d left.", r);
+                        else
+                                log_error_errno(r, "Failed to deactivate swaps: %m");
+                }
+
+                if (need_loop_detach) {
+                        log_info("Detaching loop devices.");
+                        r = loopback_detach_all(&changed, last_try);
+                        if (r == 0) {
+                                need_loop_detach = false;
+                                log_info("All loop devices detached.");
+                        } else if (r > 0)
+                                log_info("Not all loop devices detached, %d left.", r);
+                        else
+                                log_error_errno(r, "Failed to detach loop devices: %m");
+                }
+
+                if (need_md_detach) {
+                        log_info("Stopping MD devices.");
+                        r = md_detach_all(&changed, last_try);
+                        if (r == 0) {
+                                need_md_detach = false;
+                                log_info("All MD devices stopped.");
+                        } else if (r > 0)
+                                log_info("Not all MD devices stopped, %d left.", r);
+                        else
+                                log_error_errno(r, "Failed to stop MD devices: %m");
+                }
+
+                if (need_dm_detach) {
+                        log_info("Detaching DM devices.");
+                        r = dm_detach_all(&changed, last_try);
+                        if (r == 0) {
+                                need_dm_detach = false;
+                                log_info("All DM devices detached.");
+                        } else if (r > 0)
+                                log_info("Not all DM devices detached, %d left.", r);
+                        else
+                                log_error_errno(r, "Failed to detach DM devices: %m");
+                }
+
+                if (!need_umount && !need_swapoff && !need_loop_detach && !need_dm_detach
+                            && !need_md_detach) {
+                        log_info("All filesystems, swaps, loop devices, MD devices and DM devices detached.");
+                        /* Yay, done */
+                        break;
+                }
+
+                if (!changed && !last_try && !can_initrd) {
+                        /* There are things we cannot get rid of. Loop one more time in which we will log
+                         * with higher priority to inform the user. Note that we don't need to do this if
+                         * there is an initrd to switch to, because that one is likely to get rid of the
+                         * remaining mounts. If not, it will log about them. */
+                        last_try = true;
+                        continue;
+                }
+
+                /* If in this iteration we didn't manage to unmount/deactivate anything, we simply give up */
+                if (!changed) {
+                        log_info("Cannot finalize remaining%s%s%s%s%s continuing.",
+                                 need_umount ? " file systems," : "",
+                                 need_swapoff ? " swap devices," : "",
+                                 need_loop_detach ? " loop devices," : "",
+                                 need_dm_detach ? " DM devices," : "",
+                                 need_md_detach ? " MD devices," : "");
+                        break;
+                }
+
+                log_debug("Couldn't finalize remaining %s%s%s%s%s trying again.",
+                          need_umount ? " file systems," : "",
+                          need_swapoff ? " swap devices," : "",
+                          need_loop_detach ? " loop devices," : "",
+                          need_dm_detach ? " DM devices," : "",
+                          need_md_detach ? " MD devices," : "");
+        }
+
+        /* We're done with the watchdog. Note that the watchdog is explicitly not stopped here. It remains
+         * active to guard against any issues during the rest of the shutdown sequence. */
+        watchdog_free_device();
+
+        arguments[0] = NULL; /* Filled in by execute_directories(), when needed */
+        arguments[1] = arg_verb;
+        arguments[2] = NULL;
+        (void) execute_directories(dirs, DEFAULT_TIMEOUT_USEC, NULL, NULL, arguments, NULL, EXEC_DIR_PARALLEL | EXEC_DIR_IGNORE_ERRORS);
+
+        (void) rlimit_nofile_safe();
+
+        if (can_initrd) {
+                r = switch_root_initramfs();
+                if (r >= 0) {
+                        argv[0] = (char*) "/shutdown";
+
+                        (void) setsid();
+                        (void) make_console_stdio();
+
+                        log_info("Successfully changed into root pivot.\n"
+                                 "Returning to initrd...");
+
+                        execv("/shutdown", argv);
+                        log_error_errno(errno, "Failed to execute shutdown binary: %m");
+                } else
+                        log_error_errno(r, "Failed to switch root to \"/run/initramfs\": %m");
+        }
+
+        if (need_umount || need_swapoff || need_loop_detach || need_dm_detach || need_md_detach)
+                log_error("Failed to finalize%s%s%s%s%s ignoring.",
+                          need_umount ? " file systems," : "",
+                          need_swapoff ? " swap devices," : "",
+                          need_loop_detach ? " loop devices," : "",
+                          need_dm_detach ? " DM devices," : "",
+                          need_md_detach ? " MD devices," : "");
+
+        /* The kernel will automatically flush ATA disks and suchlike on reboot(), but the file systems need
+         * to be sync'ed explicitly in advance. So let's do this here, but not needlessly slow down
+         * containers. Note that we sync'ed things already once above, but we did some more work since then
+         * which might have caused IO, hence let's do it once more. Do not remove this sync, data corruption
+         * will result. */
+        if (!in_container)
+                sync_with_progress();
+
+        if (streq(arg_verb, "exit")) {
+                if (in_container) {
+                        log_info("Exiting container.");
+                        return arg_exit_code;
+                }
+
+                cmd = RB_POWER_OFF; /* We cannot exit() on the host, fallback on another method. */
+        }
+
+        switch (cmd) {
+
+        case LINUX_REBOOT_CMD_KEXEC:
+
+                if (!in_container) {
+                        /* We cheat and exec kexec to avoid doing all its work */
+                        log_info("Rebooting with kexec.");
+
+                        r = safe_fork("(sd-kexec)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_WAIT, NULL);
+                        if (r == 0) {
+                                const char * const args[] = {
+                                        KEXEC, "-e", NULL
+                                };
+
+                                /* Child */
+
+                                execv(args[0], (char * const *) args);
+                                log_debug_errno(errno, "Failed to execute '" KEXEC "' binary, proceeding with reboot(RB_KEXEC): %m");
+
+                                /* execv failed (kexec binary missing?), so try simply reboot(RB_KEXEC) */
+                                (void) reboot(cmd);
+                                _exit(EXIT_FAILURE);
+                        }
+
+                        /* If we are still running, then the kexec can't have worked, let's fall through */
+                }
+
+                cmd = RB_AUTOBOOT;
+                _fallthrough_;
+
+        case RB_AUTOBOOT:
+                (void) reboot_with_parameter(REBOOT_LOG);
+                log_info("Rebooting.");
+                break;
+
+        case RB_POWER_OFF:
+                log_info("Powering off.");
+                break;
+
+        case RB_HALT_SYSTEM:
+                log_info("Halting system.");
+                break;
+
+        default:
+                assert_not_reached();
+        }
+
+        (void) reboot(cmd);
+        if (ERRNO_IS_PRIVILEGE(errno) && in_container) {
+                /* If we are in a container, and we lacked CAP_SYS_BOOT just exit, this will kill our
+                 * container for good. */
+                log_info("Exiting container.");
+                return EXIT_SUCCESS;
+        }
+
+        r = log_error_errno(errno, "Failed to invoke reboot(): %m");
+
+  error:
+        log_emergency_errno(r, "Critical error while doing system shutdown: %m");
+        freeze();
+}
diff --git a/src/shutdown/test-umount.c b/src/shutdown/test-umount.c
new file mode 100644
index 0000000..c92105b
--- /dev/null
+++ b/src/shutdown/test-umount.c
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "errno-util.h"
+#include "log.h"
+#include "path-util.h"
+#include "string-util.h"
+#include "tests.h"
+#include "umount.h"
+#include "util.h"
+
+static void test_mount_points_list_one(const char *fname) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, mp_list_head);
+        _cleanup_free_ char *testdata_fname = NULL;
+
+        log_info("/* %s(\"%s\") */", __func__, fname ?: "/proc/self/mountinfo");
+
+        if (fname) {
+                assert_se(get_testdata_dir(fname, &testdata_fname) >= 0);
+                fname = testdata_fname;
+        }
+
+        LIST_HEAD_INIT(mp_list_head);
+        assert_se(mount_points_list_get(fname, &mp_list_head) >= 0);
+
+        LIST_FOREACH(mount_point, m, mp_list_head)
+                log_debug("path=%s o=%s f=0x%lx try-ro=%s dev=%u:%u",
+                          m->path,
+                          strempty(m->remount_options),
+                          m->remount_flags,
+                          yes_no(m->try_remount_ro),
+                          major(m->devnum), minor(m->devnum));
+}
+
+TEST(mount_points_list) {
+        test_mount_points_list_one(NULL);
+        test_mount_points_list_one("/test-umount/empty.mountinfo");
+        test_mount_points_list_one("/test-umount/garbled.mountinfo");
+        test_mount_points_list_one("/test-umount/rhbug-1554943.mountinfo");
+}
+
+static void test_swap_list_one(const char *fname) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, mp_list_head);
+        _cleanup_free_ char *testdata_fname = NULL;
+        int r;
+
+        log_info("/* %s(\"%s\") */", __func__, fname ?: "/proc/swaps");
+
+        if (fname) {
+                assert_se(get_testdata_dir(fname, &testdata_fname) >= 0);
+                fname = testdata_fname;
+        }
+
+        LIST_HEAD_INIT(mp_list_head);
+        r = swap_list_get(fname, &mp_list_head);
+        if (ERRNO_IS_PRIVILEGE(r))
+                return;
+        assert_se(r >= 0);
+
+        LIST_FOREACH(mount_point, m, mp_list_head)
+                log_debug("path=%s o=%s f=0x%lx try-ro=%s dev=%u:%u",
+                          m->path,
+                          strempty(m->remount_options),
+                          m->remount_flags,
+                          yes_no(m->try_remount_ro),
+                          major(m->devnum), minor(m->devnum));
+}
+
+TEST(swap_list) {
+        test_swap_list_one(NULL);
+        test_swap_list_one("/test-umount/example.swaps");
+}
+
+DEFINE_TEST_MAIN(LOG_DEBUG);
diff --git a/src/shutdown/umount.c b/src/shutdown/umount.c
new file mode 100644
index 0000000..e650b82
--- /dev/null
+++ b/src/shutdown/umount.c
@@ -0,0 +1,932 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2010 ProFUSION embedded systems
+***/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/dm-ioctl.h>
+#include <linux/major.h>
+#include <linux/raid/md_u.h>
+#include <linux/loop.h>
+#include <sys/mount.h>
+#include <sys/swap.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if HAVE_VALGRIND_MEMCHECK_H
+#include <valgrind/memcheck.h>
+#endif
+
+#include "sd-device.h"
+
+#include "alloc-util.h"
+#include "blockdev-util.h"
+#include "def.h"
+#include "device-util.h"
+#include "dirent-util.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "fstab-util.h"
+#include "libmount-util.h"
+#include "mount-setup.h"
+#include "mount-util.h"
+#include "mountpoint-util.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "signal-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "sync-util.h"
+#include "umount.h"
+#include "util.h"
+#include "virt.h"
+
+static void mount_point_free(MountPoint **head, MountPoint *m) {
+        assert(head);
+        assert(m);
+
+        LIST_REMOVE(mount_point, *head, m);
+
+        free(m->path);
+        free(m->remount_options);
+        free(m);
+}
+
+void mount_points_list_free(MountPoint **head) {
+        assert(head);
+
+        while (*head)
+                mount_point_free(head, *head);
+}
+
+int mount_points_list_get(const char *mountinfo, MountPoint **head) {
+        _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL;
+        _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL;
+        int r;
+
+        assert(head);
+
+        r = libmount_parse(mountinfo, NULL, &table, &iter);
+        if (r < 0)
+                return log_error_errno(r, "Failed to parse %s: %m", mountinfo ?: "/proc/self/mountinfo");
+
+        for (;;) {
+                _cleanup_free_ char *options = NULL, *remount_options = NULL;
+                struct libmnt_fs *fs;
+                const char *path, *fstype;
+                unsigned long remount_flags = 0u;
+                bool try_remount_ro, is_api_vfs;
+                _cleanup_free_ MountPoint *m = NULL;
+
+                r = mnt_table_next_fs(table, iter, &fs);
+                if (r == 1) /* EOF */
+                        break;
+                if (r < 0)
+                        return log_error_errno(r, "Failed to get next entry from %s: %m", mountinfo ?: "/proc/self/mountinfo");
+
+                path = mnt_fs_get_target(fs);
+                if (!path)
+                        continue;
+
+                fstype = mnt_fs_get_fstype(fs);
+
+                /* Combine the generic VFS options with the FS-specific options. Duplicates are not a problem
+                 * here, because the only options that should come up twice are typically ro/rw, which are
+                 * turned into MS_RDONLY or the inversion of it.
+                 *
+                 * Even if there are duplicates later in mount_option_mangle() they shouldn't hurt anyways as
+                 * they override each other. */
+                if (!strextend_with_separator(&options, ",", mnt_fs_get_vfs_options(fs)))
+                        return log_oom();
+                if (!strextend_with_separator(&options, ",", mnt_fs_get_fs_options(fs)))
+                        return log_oom();
+
+                /* Ignore mount points we can't unmount because they are API or because we are keeping them
+                 * open (like /dev/console). Also, ignore all mounts below API file systems, since they are
+                 * likely virtual too, and hence not worth spending time on. Also, in unprivileged containers
+                 * we might lack the rights to unmount these things, hence don't bother. */
+                if (mount_point_is_api(path) ||
+                    mount_point_ignore(path) ||
+                    PATH_STARTSWITH_SET(path, "/dev", "/sys", "/proc"))
+                        continue;
+
+                is_api_vfs = fstype_is_api_vfs(fstype);
+
+                /* If we are in a container, don't attempt to read-only mount anything as that brings no real
+                 * benefits, but might confuse the host, as we remount the superblock here, not the bind
+                 * mount.
+                 *
+                 * If the filesystem is a network fs, also skip the remount. It brings no value (we cannot
+                 * leave a "dirty fs") and could hang if the network is down.  Note that umount2() is more
+                 * careful and will not hang because of the network being down. */
+                try_remount_ro = detect_container() <= 0 &&
+                                 !fstype_is_network(fstype) &&
+                                 !is_api_vfs &&
+                                 !fstype_is_ro(fstype) &&
+                                 !fstab_test_yes_no_option(options, "ro\0rw\0");
+
+                if (try_remount_ro) {
+                        /* mount(2) states that mount flags and options need to be exactly the same as they
+                         * were when the filesystem was mounted, except for the desired changes. So we
+                         * reconstruct both here and adjust them for the later remount call too. */
+
+                        r = mnt_fs_get_propagation(fs, &remount_flags);
+                        if (r < 0) {
+                                log_warning_errno(r, "mnt_fs_get_propagation() failed for %s, ignoring: %m", path);
+                                continue;
+                        }
+
+                        r = mount_option_mangle(options, remount_flags, &remount_flags, &remount_options);
+                        if (r < 0) {
+                                log_warning_errno(r, "mount_option_mangle failed for %s, ignoring: %m", path);
+                                continue;
+                        }
+
+                        /* MS_BIND is special. If it is provided it will only make the mount-point
+                         * read-only. If left out, the super block itself is remounted, which we want. */
+                        remount_flags = (remount_flags|MS_REMOUNT|MS_RDONLY) & ~MS_BIND;
+                }
+
+                m = new(MountPoint, 1);
+                if (!m)
+                        return log_oom();
+
+                *m = (MountPoint) {
+                        .remount_options = remount_options,
+                        .remount_flags = remount_flags,
+                        .try_remount_ro = try_remount_ro,
+
+                        /* Unmount sysfs/procfs/… lazily, since syncing doesn't matter there, and it's OK if
+                         * something keeps an fd open to it. */
+                        .umount_lazily = is_api_vfs,
+                };
+
+                m->path = strdup(path);
+                if (!m->path)
+                        return log_oom();
+
+                TAKE_PTR(remount_options);
+
+                LIST_PREPEND(mount_point, *head, TAKE_PTR(m));
+        }
+
+        return 0;
+}
+
+int swap_list_get(const char *swaps, MountPoint **head) {
+        _cleanup_(mnt_free_tablep) struct libmnt_table *t = NULL;
+        _cleanup_(mnt_free_iterp) struct libmnt_iter *i = NULL;
+        int r;
+
+        assert(head);
+
+        t = mnt_new_table();
+        i = mnt_new_iter(MNT_ITER_FORWARD);
+        if (!t || !i)
+                return log_oom();
+
+        r = mnt_table_parse_swaps(t, swaps);
+        if (r == -ENOENT) /* no /proc/swaps is fine */
+                return 0;
+        if (r < 0)
+                return log_error_errno(r, "Failed to parse %s: %m", swaps ?: "/proc/swaps");
+
+        for (;;) {
+                struct libmnt_fs *fs;
+                _cleanup_free_ MountPoint *swap = NULL;
+                const char *source;
+
+                r = mnt_table_next_fs(t, i, &fs);
+                if (r == 1) /* EOF */
+                        break;
+                if (r < 0)
+                        return log_error_errno(r, "Failed to get next entry from %s: %m", swaps ?: "/proc/swaps");
+
+                source = mnt_fs_get_source(fs);
+                if (!source)
+                        continue;
+
+                swap = new0(MountPoint, 1);
+                if (!swap)
+                        return log_oom();
+
+                swap->path = strdup(source);
+                if (!swap->path)
+                        return log_oom();
+
+                LIST_PREPEND(mount_point, *head, TAKE_PTR(swap));
+        }
+
+        return 0;
+}
+
+static int loopback_list_get(MountPoint **head) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        sd_device *d;
+        int r;
+
+        assert(head);
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_subsystem(e, "block", true);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysname(e, "loop*");
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysattr(e, "loop/backing_file", NULL, true);
+        if (r < 0)
+                return r;
+
+        FOREACH_DEVICE(e, d) {
+                _cleanup_free_ char *p = NULL;
+                const char *dn;
+                MountPoint *lb;
+                dev_t devnum;
+
+                if (sd_device_get_devnum(d, &devnum) < 0 ||
+                    sd_device_get_devname(d, &dn) < 0)
+                        continue;
+
+                p = strdup(dn);
+                if (!p)
+                        return -ENOMEM;
+
+                lb = new(MountPoint, 1);
+                if (!lb)
+                        return -ENOMEM;
+
+                *lb = (MountPoint) {
+                        .path = TAKE_PTR(p),
+                        .devnum = devnum,
+                };
+
+                LIST_PREPEND(mount_point, *head, lb);
+        }
+
+        return 0;
+}
+
+static int dm_list_get(MountPoint **head) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        sd_device *d;
+        int r;
+
+        assert(head);
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_subsystem(e, "block", true);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysname(e, "dm-*");
+        if (r < 0)
+                return r;
+
+        FOREACH_DEVICE(e, d) {
+                _cleanup_free_ char *p = NULL;
+                const char *dn;
+                MountPoint *m;
+                dev_t devnum;
+
+                if (sd_device_get_devnum(d, &devnum) < 0 ||
+                    sd_device_get_devname(d, &dn) < 0)
+                        continue;
+
+                p = strdup(dn);
+                if (!p)
+                        return -ENOMEM;
+
+                m = new(MountPoint, 1);
+                if (!m)
+                        return -ENOMEM;
+
+                *m = (MountPoint) {
+                        .path = TAKE_PTR(p),
+                        .devnum = devnum,
+                };
+
+                LIST_PREPEND(mount_point, *head, m);
+        }
+
+        return 0;
+}
+
+static int md_list_get(MountPoint **head) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        sd_device *d;
+        int r;
+
+        assert(head);
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_subsystem(e, "block", true);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysname(e, "md*");
+        if (r < 0)
+                return r;
+
+        /* Filter out partitions. */
+        r = sd_device_enumerator_add_match_property(e, "DEVTYPE", "disk");
+        if (r < 0)
+                return r;
+
+        FOREACH_DEVICE(e, d) {
+                _cleanup_free_ char *p = NULL;
+                const char *dn, *md_level;
+                MountPoint *m;
+                dev_t devnum;
+
+                if (sd_device_get_devnum(d, &devnum) < 0 ||
+                    sd_device_get_devname(d, &dn) < 0)
+                        continue;
+
+                r = sd_device_get_property_value(d, "MD_LEVEL", &md_level);
+                if (r < 0) {
+                        log_warning_errno(r, "Failed to get MD_LEVEL property for %s, ignoring: %m", dn);
+                        continue;
+                }
+
+                /* MD "containers" are a special type of MD devices, used for external metadata.  Since it
+                 * doesn't provide RAID functionality in itself we don't need to stop it. */
+                if (streq(md_level, "container"))
+                        continue;
+
+                p = strdup(dn);
+                if (!p)
+                        return -ENOMEM;
+
+                m = new(MountPoint, 1);
+                if (!m)
+                        return -ENOMEM;
+
+                *m = (MountPoint) {
+                        .path = TAKE_PTR(p),
+                        .devnum = devnum,
+                };
+
+                LIST_PREPEND(mount_point, *head, m);
+        }
+
+        return 0;
+}
+
+static int delete_loopback(const char *device) {
+        _cleanup_close_ int fd = -1;
+        struct loop_info64 info;
+
+        assert(device);
+
+        fd = open(device, O_RDONLY|O_CLOEXEC);
+        if (fd < 0) {
+                log_debug_errno(errno, "Failed to open loopback device %s: %m", device);
+                return errno == ENOENT ? 0 : -errno;
+        }
+
+        /* Loopback block devices don't sync in-flight blocks when we clear the fd, hence sync explicitly
+         * first */
+        if (fsync(fd) < 0)
+                log_debug_errno(errno, "Failed to sync loop block device %s, ignoring: %m", device);
+
+        if (ioctl(fd, LOOP_CLR_FD, 0) < 0) {
+                if (errno == ENXIO) /* Nothing bound, didn't do anything */
+                        return 0;
+
+                if (errno != EBUSY)
+                        return log_debug_errno(errno, "Failed to clear loopback device %s: %m", device);
+
+                if (ioctl(fd, LOOP_GET_STATUS64, &info) < 0) {
+                        if (errno == ENXIO) /* What? Suddenly detached after all? That's fine by us then. */
+                                return 1;
+
+                        log_debug_errno(errno, "Failed to invoke LOOP_GET_STATUS64 on loopback device %s, ignoring: %m", device);
+                        return -EBUSY; /* propagate original error */
+                }
+
+#if HAVE_VALGRIND_MEMCHECK_H
+                VALGRIND_MAKE_MEM_DEFINED(&info, sizeof(info));
+#endif
+
+                if (FLAGS_SET(info.lo_flags, LO_FLAGS_AUTOCLEAR)) /* someone else already set LO_FLAGS_AUTOCLEAR for us? fine by us */
+                        return -EBUSY; /* propagate original error */
+
+                info.lo_flags |= LO_FLAGS_AUTOCLEAR;
+                if (ioctl(fd, LOOP_SET_STATUS64, &info) < 0) {
+                        if (errno == ENXIO) /* Suddenly detached after all? Fine by us */
+                                return 1;
+
+                        log_debug_errno(errno, "Failed to set LO_FLAGS_AUTOCLEAR flag for loop device %s, ignoring: %m", device);
+                } else
+                        log_debug("Successfully set LO_FLAGS_AUTOCLEAR flag for loop device %s.", device);
+
+                return -EBUSY;
+        }
+
+        if (ioctl(fd, LOOP_GET_STATUS64, &info) < 0) {
+                /* If the LOOP_CLR_FD above succeeded we'll see ENXIO here. */
+                if (errno == ENXIO)
+                        log_debug("Successfully detached loopback device %s.", device);
+                else
+                        log_debug_errno(errno, "Failed to invoke LOOP_GET_STATUS64 on loopback device %s, ignoring: %m", device); /* the LOOP_CLR_FD at least worked, let's hope for the best */
+
+                return 1;
+        }
+
+#if HAVE_VALGRIND_MEMCHECK_H
+        VALGRIND_MAKE_MEM_DEFINED(&info, sizeof(info));
+#endif
+
+        /* Linux makes LOOP_CLR_FD succeed whenever LO_FLAGS_AUTOCLEAR is set without actually doing
+         * anything. Very confusing. Let's hence not claim we did anything in this case. */
+        if (FLAGS_SET(info.lo_flags, LO_FLAGS_AUTOCLEAR))
+                log_debug("Successfully called LOOP_CLR_FD on a loopback device %s with autoclear set, which is a NOP.", device);
+        else
+                log_debug("Weird, LOOP_CLR_FD succeeded but the device is still attached on %s.", device);
+
+        return -EBUSY; /* Nothing changed, the device is still attached, hence it apparently is still busy */
+}
+
+static int delete_dm(MountPoint *m) {
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        assert(m);
+        assert(major(m->devnum) != 0);
+        assert(m->path);
+
+        fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        r = fsync_path_at(AT_FDCWD, m->path);
+        if (r < 0)
+                log_debug_errno(r, "Failed to sync DM block device %s, ignoring: %m", m->path);
+
+        return RET_NERRNO(ioctl(fd, DM_DEV_REMOVE, &(struct dm_ioctl) {
+                .version = {
+                        DM_VERSION_MAJOR,
+                        DM_VERSION_MINOR,
+                        DM_VERSION_PATCHLEVEL
+                },
+                .data_size = sizeof(struct dm_ioctl),
+                .dev = m->devnum,
+        }));
+}
+
+static int delete_md(MountPoint *m) {
+        _cleanup_close_ int fd = -1;
+
+        assert(m);
+        assert(major(m->devnum) != 0);
+        assert(m->path);
+
+        fd = open(m->path, O_RDONLY|O_CLOEXEC|O_EXCL);
+        if (fd < 0)
+                return -errno;
+
+        if (fsync(fd) < 0)
+                log_debug_errno(errno, "Failed to sync MD block device %s, ignoring: %m", m->path);
+
+        return RET_NERRNO(ioctl(fd, STOP_ARRAY, NULL));
+}
+
+static bool nonunmountable_path(const char *path) {
+        return path_equal(path, "/")
+#if ! HAVE_SPLIT_USR
+                || path_equal(path, "/usr")
+#endif
+                || path_startswith(path, "/run/initramfs");
+}
+
+static void log_umount_blockers(const char *mnt) {
+        _cleanup_free_ char *blockers = NULL;
+        int r;
+
+        _cleanup_closedir_ DIR *dir = opendir("/proc");
+        if (!dir)
+                return (void) log_warning_errno(errno, "Failed to open /proc/: %m");
+
+        FOREACH_DIRENT_ALL(de, dir, break) {
+                if (!IN_SET(de->d_type, DT_DIR, DT_UNKNOWN))
+                        continue;
+
+                pid_t pid;
+                if (parse_pid(de->d_name, &pid) < 0)
+                        continue;
+
+                _cleanup_free_ char *fdp = path_join(de->d_name, "fd");
+                if (!fdp)
+                        return (void) log_oom();
+
+                _cleanup_closedir_ DIR *fd_dir = xopendirat(dirfd(dir), fdp, 0);
+                if (!fd_dir) {
+                        if (errno != ENOENT) /* process gone by now? */
+                                log_debug_errno(errno, "Failed to open /proc/%s/, ignoring: %m",fdp);
+                        continue;
+                }
+
+                bool culprit = false;
+                FOREACH_DIRENT(fd_de, fd_dir, break) {
+                        _cleanup_free_ char *open_file = NULL;
+
+                        r = readlinkat_malloc(dirfd(fd_dir), fd_de->d_name, &open_file);
+                        if (r < 0) {
+                                if (r != -ENOENT) /* fd closed by now */
+                                        log_debug_errno(r, "Failed to read link /proc/%s/%s, ignoring: %m", fdp, fd_de->d_name);
+                                continue;
+                        }
+
+                        if (path_startswith(open_file, mnt)) {
+                                culprit = true;
+                                break;
+                        }
+                }
+
+                if (!culprit)
+                        continue;
+
+                _cleanup_free_ char *comm = NULL;
+                r = get_process_comm(pid, &comm);
+                if (r < 0) {
+                        if (r != -ESRCH) /* process gone by now */
+                                log_debug_errno(r, "Failed to read process name of PID " PID_FMT ": %m", pid);
+                        continue;
+                }
+
+                if (!strextend_with_separator(&blockers, ", ", comm))
+                        return (void) log_oom();
+
+                if (!strextend(&blockers, "(", de->d_name, ")"))
+                        return (void) log_oom();
+        }
+
+        if (blockers)
+                log_warning("Unmounting '%s' blocked by: %s", mnt, blockers);
+}
+
+static int remount_with_timeout(MountPoint *m, bool last_try) {
+        pid_t pid;
+        int r;
+
+        BLOCK_SIGNALS(SIGCHLD);
+
+        assert(m);
+
+        /* Due to the possibility of a remount operation hanging, we fork a child process and set a
+         * timeout. If the timeout lapses, the assumption is that the particular remount failed. */
+        r = safe_fork("(sd-remount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                log_info("Remounting '%s' read-only with options '%s'.", m->path, strempty(m->remount_options));
+
+                /* Start the mount operation here in the child */
+                r = mount(NULL, m->path, NULL, m->remount_flags, m->remount_options);
+                if (r < 0)
+                        log_full_errno(last_try ? LOG_ERR : LOG_INFO,
+                                       errno,
+                                       "Failed to remount '%s' read-only: %m",
+                                       m->path);
+
+                _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
+        }
+
+        r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC);
+        if (r == -ETIMEDOUT) {
+                log_error_errno(r, "Remounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid);
+                (void) kill(pid, SIGKILL);
+        } else if (r == -EPROTO)
+                log_debug_errno(r, "Remounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid);
+        else if (r < 0)
+                log_error_errno(r, "Remounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid);
+
+        return r;
+}
+
+static int umount_with_timeout(MountPoint *m, bool last_try) {
+        pid_t pid;
+        int r;
+
+        BLOCK_SIGNALS(SIGCHLD);
+
+        assert(m);
+
+        /* Due to the possibility of a umount operation hanging, we fork a child process and set a
+         * timeout. If the timeout lapses, the assumption is that the particular umount failed. */
+        r = safe_fork("(sd-umount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                log_info("Unmounting '%s'.", m->path);
+
+                /* Start the mount operation here in the child Using MNT_FORCE causes some filesystems
+                 * (e.g. FUSE and NFS and other network filesystems) to abort any pending requests and return
+                 * -EIO rather than blocking indefinitely. If the filesysten is "busy", this may allow
+                 * processes to die, thus making the filesystem less busy so the unmount might succeed
+                 * (rather than return EBUSY). */
+                r = RET_NERRNO(umount2(m->path,
+                                       UMOUNT_NOFOLLOW | /* Don't follow symlinks: this should never happen unless our mount list was wrong */
+                                       (m->umount_lazily ? MNT_DETACH : MNT_FORCE)));
+                if (r < 0) {
+                        log_full_errno(last_try ? LOG_ERR : LOG_INFO, r, "Failed to unmount %s: %m", m->path);
+
+                        if (r == -EBUSY && last_try)
+                                log_umount_blockers(m->path);
+                }
+
+                _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
+        }
+
+        r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC);
+        if (r == -ETIMEDOUT) {
+                log_error_errno(r, "Unmounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid);
+                (void) kill(pid, SIGKILL);
+        } else if (r == -EPROTO)
+                log_debug_errno(r, "Unmounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid);
+        else if (r < 0)
+                log_error_errno(r, "Unmounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid);
+
+        return r;
+}
+
+/* This includes remounting readonly, which changes the kernel mount options.  Therefore the list passed to
+ * this function is invalidated, and should not be reused. */
+static int mount_points_list_umount(MountPoint **head, bool *changed, bool last_try) {
+        int n_failed = 0;
+
+        assert(head);
+        assert(changed);
+
+        LIST_FOREACH(mount_point, m, *head) {
+                if (m->try_remount_ro) {
+                        /* We always try to remount directories read-only first, before we go on and umount
+                         * them.
+                         *
+                         * Mount points can be stacked. If a mount point is stacked below / or /usr, we
+                         * cannot umount or remount it directly, since there is no way to refer to the
+                         * underlying mount. There's nothing we can do about it for the general case, but we
+                         * can do something about it if it is aliased somewhere else via a bind mount. If we
+                         * explicitly remount the super block of that alias read-only we hence should be
+                         * relatively safe regarding keeping a dirty fs we cannot otherwise see.
+                         *
+                         * Since the remount can hang in the instance of remote filesystems, we remount
+                         * asynchronously and skip the subsequent umount if it fails. */
+                        if (remount_with_timeout(m, last_try) < 0) {
+                                /* Remount failed, but try unmounting anyway,
+                                 * unless this is a mount point we want to skip. */
+                                if (nonunmountable_path(m->path)) {
+                                        n_failed++;
+                                        continue;
+                                }
+                        }
+                }
+
+                /* Skip / and /usr since we cannot unmount that anyway, since we are running from it. They
+                 * have already been remounted ro. */
+                if (nonunmountable_path(m->path))
+                        continue;
+
+                /* Trying to umount */
+                if (umount_with_timeout(m, last_try) < 0)
+                        n_failed++;
+                else
+                        *changed = true;
+        }
+
+        return n_failed;
+}
+
+static int swap_points_list_off(MountPoint **head, bool *changed) {
+        int n_failed = 0;
+
+        assert(head);
+        assert(changed);
+
+        LIST_FOREACH(mount_point, m, *head) {
+                log_info("Deactivating swap %s.", m->path);
+                if (swapoff(m->path) < 0) {
+                        log_warning_errno(errno, "Could not deactivate swap %s: %m", m->path);
+                        n_failed++;
+                        continue;
+                }
+
+                *changed = true;
+                mount_point_free(head, m);
+        }
+
+        return n_failed;
+}
+
+static int loopback_points_list_detach(MountPoint **head, bool *changed, bool last_try) {
+        int n_failed = 0, r;
+        dev_t rootdev = 0;
+
+        assert(head);
+        assert(changed);
+
+        (void) get_block_device("/", &rootdev);
+
+        LIST_FOREACH(mount_point, m, *head) {
+                if (major(rootdev) != 0 && rootdev == m->devnum) {
+                        n_failed++;
+                        continue;
+                }
+
+                log_info("Detaching loopback %s.", m->path);
+                r = delete_loopback(m->path);
+                if (r < 0) {
+                        log_full_errno(last_try ? LOG_ERR : LOG_INFO, r, "Could not detach loopback %s: %m", m->path);
+                        n_failed++;
+                        continue;
+                }
+                if (r > 0)
+                        *changed = true;
+
+                mount_point_free(head, m);
+        }
+
+        return n_failed;
+}
+
+static int dm_points_list_detach(MountPoint **head, bool *changed, bool last_try) {
+        int n_failed = 0, r;
+        dev_t rootdev = 0;
+
+        assert(head);
+        assert(changed);
+
+        (void) get_block_device("/", &rootdev);
+
+        LIST_FOREACH(mount_point, m, *head) {
+                if (major(rootdev) != 0 && rootdev == m->devnum) {
+                        n_failed ++;
+                        continue;
+                }
+
+                log_info("Detaching DM %s (%u:%u).", m->path, major(m->devnum), minor(m->devnum));
+                r = delete_dm(m);
+                if (r < 0) {
+                        log_full_errno(last_try ? LOG_ERR : LOG_INFO, r, "Could not detach DM %s: %m", m->path);
+                        n_failed++;
+                        continue;
+                }
+
+                *changed = true;
+                mount_point_free(head, m);
+        }
+
+        return n_failed;
+}
+
+static int md_points_list_detach(MountPoint **head, bool *changed, bool last_try) {
+        int n_failed = 0, r;
+        dev_t rootdev = 0;
+
+        assert(head);
+        assert(changed);
+
+        (void) get_block_device("/", &rootdev);
+
+        LIST_FOREACH(mount_point, m, *head) {
+                if (major(rootdev) != 0 && rootdev == m->devnum) {
+                        n_failed ++;
+                        continue;
+                }
+
+                log_info("Stopping MD %s (%u:%u).", m->path, major(m->devnum), minor(m->devnum));
+                r = delete_md(m);
+                if (r < 0) {
+                        log_full_errno(last_try ? LOG_ERR : LOG_INFO, r, "Could not stop MD %s: %m", m->path);
+                        n_failed++;
+                        continue;
+                }
+
+                *changed = true;
+                mount_point_free(head, m);
+        }
+
+        return n_failed;
+}
+
+static int umount_all_once(bool *changed, bool last_try) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, mp_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(mp_list_head);
+        r = mount_points_list_get(NULL, &mp_list_head);
+        if (r < 0)
+                return r;
+
+        return mount_points_list_umount(&mp_list_head, changed, last_try);
+}
+
+int umount_all(bool *changed, bool last_try) {
+        bool umount_changed;
+        int r;
+
+        assert(changed);
+
+        /* Retry umount, until nothing can be umounted anymore. Mounts are processed in order, newest
+         * first. The retries are needed when an old mount has been moved, to a path inside a newer mount. */
+        do {
+                umount_changed = false;
+
+                r = umount_all_once(&umount_changed, last_try);
+                if (umount_changed)
+                        *changed = true;
+        } while (umount_changed);
+
+        return r;
+}
+
+int swapoff_all(bool *changed) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, swap_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(swap_list_head);
+
+        r = swap_list_get(NULL, &swap_list_head);
+        if (r < 0)
+                return r;
+
+        return swap_points_list_off(&swap_list_head, changed);
+}
+
+int loopback_detach_all(bool *changed, bool last_try) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, loopback_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(loopback_list_head);
+
+        r = loopback_list_get(&loopback_list_head);
+        if (r < 0)
+                return r;
+
+        return loopback_points_list_detach(&loopback_list_head, changed, last_try);
+}
+
+int dm_detach_all(bool *changed, bool last_try) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, dm_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(dm_list_head);
+
+        r = dm_list_get(&dm_list_head);
+        if (r < 0)
+                return r;
+
+        return dm_points_list_detach(&dm_list_head, changed, last_try);
+}
+
+int md_detach_all(bool *changed, bool last_try) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, md_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(md_list_head);
+
+        r = md_list_get(&md_list_head);
+        if (r < 0)
+                return r;
+
+        return md_points_list_detach(&md_list_head, changed, last_try);
+}
diff --git a/src/shutdown/umount.h b/src/shutdown/umount.h
new file mode 100644
index 0000000..a4154c9
--- /dev/null
+++ b/src/shutdown/umount.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+/***
+  Copyright © 2010 ProFUSION embedded systems
+***/
+
+#include "list.h"
+
+int umount_all(bool *changed, bool last_try);
+int swapoff_all(bool *changed);
+int loopback_detach_all(bool *changed, bool last_try);
+int dm_detach_all(bool *changed, bool last_try);
+int md_detach_all(bool *changed, bool last_try);
+
+/* This is exported just for testing */
+typedef struct MountPoint {
+        char *path;
+        char *remount_options;
+        unsigned long remount_flags;
+        bool try_remount_ro:1;
+        bool umount_lazily:1;
+        dev_t devnum;
+        LIST_FIELDS(struct MountPoint, mount_point);
+} MountPoint;
+
+int mount_points_list_get(const char *mountinfo, MountPoint **head);
+void mount_points_list_free(MountPoint **head);
+int swap_list_get(const char *swaps, MountPoint **head);