Remove snapshot unit type

Snapshots were never useful or used for anything. Many systemd
developers that I spoke to at systemd.conf2015, didn't even know they
existed, so it is fairly safe to assume that this type can be deleted
without harm.

The fundamental problem with snapshots is that the state of the system
is dynamic, devices come and go, users log in and out, timers fire...
and restoring all units to some state from the past would "undo"
those changes, which isn't really possible.

Tested by creating a snapshot, running the new binary, and checking
that the transition did not cause errors, and the snapshot is gone,
and snapshots cannot be created anymore.

New systemctl says:
Unknown operation snapshot.
Old systemctl says:
Failed to create snapshot: Support for snapshots has been removed.

IgnoreOnSnaphost settings are warned about and ignored:
Support for option IgnoreOnSnapshot= has been removed and it is ignored

http://lists.freedesktop.org/archives/systemd-devel/2015-November/034872.html

17 files changed, 7 insertions, 644 deletions

diff --git a/src/basic/unit-name.c b/src/basic/unit-name.c
index 710421508c..5007ecf1a4 100644
--- a/src/basic/unit-name.c
+++ b/src/basic/unit-name.c
@@ -597,7 +597,6 @@ const char* unit_dbus_interface_from_type(UnitType t) {
                 [UNIT_SOCKET] = "org.freedesktop.systemd1.Socket",
                 [UNIT_BUSNAME] = "org.freedesktop.systemd1.BusName",
                 [UNIT_TARGET] = "org.freedesktop.systemd1.Target",
-                [UNIT_SNAPSHOT] = "org.freedesktop.systemd1.Snapshot",
                 [UNIT_DEVICE] = "org.freedesktop.systemd1.Device",
                 [UNIT_MOUNT] = "org.freedesktop.systemd1.Mount",
                 [UNIT_AUTOMOUNT] = "org.freedesktop.systemd1.Automount",
@@ -819,7 +818,6 @@ static const char* const unit_type_table[_UNIT_TYPE_MAX] = {
         [UNIT_SOCKET] = "socket",
         [UNIT_BUSNAME] = "busname",
         [UNIT_TARGET] = "target",
-        [UNIT_SNAPSHOT] = "snapshot",
         [UNIT_DEVICE] = "device",
         [UNIT_MOUNT] = "mount",
         [UNIT_AUTOMOUNT] = "automount",
@@ -950,13 +948,6 @@ static const char* const slice_state_table[_SLICE_STATE_MAX] = {
 
 DEFINE_STRING_TABLE_LOOKUP(slice_state, SliceState);
 
-static const char* const snapshot_state_table[_SNAPSHOT_STATE_MAX] = {
-        [SNAPSHOT_DEAD] = "dead",
-        [SNAPSHOT_ACTIVE] = "active"
-};
-
-DEFINE_STRING_TABLE_LOOKUP(snapshot_state, SnapshotState);
-
 static const char* const socket_state_table[_SOCKET_STATE_MAX] = {
         [SOCKET_DEAD] = "dead",
         [SOCKET_START_PRE] = "start-pre",
diff --git a/src/basic/unit-name.h b/src/basic/unit-name.h
index 65b55d9554..5f6d8299c5 100644
--- a/src/basic/unit-name.h
+++ b/src/basic/unit-name.h
@@ -32,7 +32,6 @@ typedef enum UnitType {
         UNIT_SOCKET,
         UNIT_BUSNAME,
         UNIT_TARGET,
-        UNIT_SNAPSHOT,
         UNIT_DEVICE,
         UNIT_MOUNT,
         UNIT_AUTOMOUNT,
@@ -165,13 +164,6 @@ typedef enum SliceState {
         _SLICE_STATE_INVALID = -1
 } SliceState;
 
-typedef enum SnapshotState {
-        SNAPSHOT_DEAD,
-        SNAPSHOT_ACTIVE,
-        _SNAPSHOT_STATE_MAX,
-        _SNAPSHOT_STATE_INVALID = -1
-} SnapshotState;
-
 typedef enum SocketState {
         SOCKET_DEAD,
         SOCKET_START_PRE,
@@ -366,9 +358,6 @@ ServiceState service_state_from_string(const char *s) _pure_;
 const char* slice_state_to_string(SliceState i) _const_;
 SliceState slice_state_from_string(const char *s) _pure_;
 
-const char* snapshot_state_to_string(SnapshotState i) _const_;
-SnapshotState snapshot_state_from_string(const char *s) _pure_;
-
 const char* socket_state_to_string(SocketState i) _const_;
 SocketState socket_state_from_string(const char *s) _pure_;
 
diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index 1f9f25093d..eaa0fb2b37 100644
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -31,7 +31,6 @@
 #include "dbus-execute.h"
 #include "dbus-job.h"
 #include "dbus-manager.h"
-#include "dbus-snapshot.h"
 #include "dbus-unit.h"
 #include "dbus.h"
 #include "env-util.h"
@@ -1101,66 +1100,8 @@ static int method_dump(sd_bus_message *message, void *userdata, sd_bus_error *er
         return sd_bus_reply_method_return(message, "s", dump);
 }
 
-static int method_create_snapshot(sd_bus_message *message, void *userdata, sd_bus_error *error) {
-        _cleanup_free_ char *path = NULL;
-        Manager *m = userdata;
-        const char *name;
-        int cleanup;
-        Snapshot *s = NULL;
-        int r;
-
-        assert(message);
-        assert(m);
-
-        r = mac_selinux_access_check(message, "start", error);
-        if (r < 0)
-                return r;
-
-        r = sd_bus_message_read(message, "sb", &name, &cleanup);
-        if (r < 0)
-                return r;
-
-        if (isempty(name))
-                name = NULL;
-
-        r = bus_verify_manage_units_async(m, message, error);
-        if (r < 0)
-                return r;
-        if (r == 0)
-                return 1; /* No authorization for now, but the async polkit stuff will call us again when it has it */
-
-        r = snapshot_create(m, name, cleanup, error, &s);
-        if (r < 0)
-                return r;
-
-        path = unit_dbus_path(UNIT(s));
-        if (!path)
-                return -ENOMEM;
-
-        return sd_bus_reply_method_return(message, "o", path);
-}
-
-static int method_remove_snapshot(sd_bus_message *message, void *userdata, sd_bus_error *error) {
-        Manager *m = userdata;
-        const char *name;
-        Unit *u;
-        int r;
-
-        assert(message);
-        assert(m);
-
-        r = sd_bus_message_read(message, "s", &name);
-        if (r < 0)
-                return r;
-
-        u = manager_get_unit(m, name);
-        if (!u)
-                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_UNIT, "Unit %s does not exist.", name);
-
-        if (u->type != UNIT_SNAPSHOT)
-                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_UNIT, "Unit %s is not a snapshot", name);
-
-        return bus_snapshot_method_remove(message, u, error);
+static int method_refuse_snapshot(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Support for snapshots has been removed.");
 }
 
 static int method_reload(sd_bus_message *message, void *userdata, sd_bus_error *error) {
@@ -2042,8 +1983,8 @@ const sd_bus_vtable bus_manager_vtable[] = {
         SD_BUS_METHOD("Subscribe", NULL, NULL, method_subscribe, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Unsubscribe", NULL, NULL, method_unsubscribe, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Dump", NULL, "s", method_dump, SD_BUS_VTABLE_UNPRIVILEGED),
-        SD_BUS_METHOD("CreateSnapshot", "sb", "o", method_create_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
-        SD_BUS_METHOD("RemoveSnapshot", "s", NULL, method_remove_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("CreateSnapshot", "sb", "o", method_refuse_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("RemoveSnapshot", "s", NULL, method_refuse_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Reload", NULL, NULL, method_reload, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Reexecute", NULL, NULL, method_reexecute, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Exit", NULL, NULL, method_exit, 0),
diff --git a/src/core/dbus-snapshot.c b/src/core/dbus-snapshot.c
deleted file mode 100644
index cfe44c9c15..0000000000
--- a/src/core/dbus-snapshot.c
+++ /dev/null
@@ -1,55 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-/***
-  This file is part of systemd.
-
-  Copyright 2010 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 "selinux-access.h"
-#include "unit.h"
-#include "dbus.h"
-#include "snapshot.h"
-#include "dbus-snapshot.h"
-
-int bus_snapshot_method_remove(sd_bus_message *message, void *userdata, sd_bus_error *error) {
-        Snapshot *s = userdata;
-        int r;
-
-        assert(message);
-        assert(s);
-
-        r = mac_selinux_unit_access_check(UNIT(s), message, "stop", error);
-        if (r < 0)
-                return r;
-
-        r = bus_verify_manage_units_async(UNIT(s)->manager, message, error);
-        if (r < 0)
-                return r;
-        if (r == 0)
-                return 1; /* No authorization for now, but the async polkit stuff will call us again when it has it */
-
-        snapshot_remove(s);
-
-        return sd_bus_reply_method_return(message, NULL);
-}
-
-const sd_bus_vtable bus_snapshot_vtable[] = {
-        SD_BUS_VTABLE_START(0),
-        SD_BUS_PROPERTY("Cleanup", "b", bus_property_get_bool, offsetof(Snapshot, cleanup), SD_BUS_VTABLE_PROPERTY_CONST),
-        SD_BUS_METHOD("Remove", NULL, NULL, bus_snapshot_method_remove, SD_BUS_VTABLE_UNPRIVILEGED),
-        SD_BUS_VTABLE_END
-};
diff --git a/src/core/dbus-snapshot.h b/src/core/dbus-snapshot.h
deleted file mode 100644
index 9288f44e15..0000000000
--- a/src/core/dbus-snapshot.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-#pragma once
-
-/***
-  This file is part of systemd.
-
-  Copyright 2010 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 "sd-bus.h"
-
-extern const sd_bus_vtable bus_snapshot_vtable[];
-
-int bus_snapshot_method_remove(sd_bus_message *message, void *userdata, sd_bus_error *error);
diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c
index 6320cd1aa9..827e13497a 100644
--- a/src/core/dbus-unit.c
+++ b/src/core/dbus-unit.c
@@ -671,7 +671,6 @@ const sd_bus_vtable bus_unit_vtable[] = {
         SD_BUS_PROPERTY("DefaultDependencies", "b", bus_property_get_bool, offsetof(Unit, default_dependencies), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("OnFailureJobMode", "s", property_get_job_mode, offsetof(Unit, on_failure_job_mode), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("IgnoreOnIsolate", "b", bus_property_get_bool, offsetof(Unit, ignore_on_isolate), SD_BUS_VTABLE_PROPERTY_CONST),
-        SD_BUS_PROPERTY("IgnoreOnSnapshot", "b", bus_property_get_bool, offsetof(Unit, ignore_on_snapshot), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("NeedDaemonReload", "b", property_get_need_daemon_reload, 0, SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("JobTimeoutUSec", "t", bus_property_get_usec, offsetof(Unit, job_timeout), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("JobTimeoutAction", "s", property_get_failure_action, offsetof(Unit, job_timeout_action), SD_BUS_VTABLE_PROPERTY_CONST),
diff --git a/src/core/device.c b/src/core/device.c
index 23ee7aee7e..6b16521305 100644
--- a/src/core/device.c
+++ b/src/core/device.c
@@ -117,7 +117,6 @@ static void device_init(Unit *u) {
         u->job_timeout = u->manager->default_timeout_start_usec;
 
         u->ignore_on_isolate = true;
-        u->ignore_on_snapshot = true;
 }
 
 static void device_done(Unit *u) {
diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index 75388659e3..75b11ee4f2 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -158,7 +158,7 @@ Unit.DefaultDependencies,        config_parse_bool,                  0,
 Unit.OnFailureJobMode,           config_parse_job_mode,              0,                             offsetof(Unit, on_failure_job_mode)
 Unit.OnFailureIsolate,           config_parse_job_mode_isolate,      0,                             offsetof(Unit, on_failure_job_mode)
 Unit.IgnoreOnIsolate,            config_parse_bool,                  0,                             offsetof(Unit, ignore_on_isolate)
-Unit.IgnoreOnSnapshot,           config_parse_bool,                  0,                             offsetof(Unit, ignore_on_snapshot)
+Unit.IgnoreOnSnapshot,           config_parse_warn_compat,           DISABLED_LEGACY,               0
 Unit.JobTimeoutSec,              config_parse_sec,                   0,                             offsetof(Unit, job_timeout)
 Unit.JobTimeoutAction,           config_parse_failure_action,        0,                             offsetof(Unit, job_timeout_action)
 Unit.JobTimeoutRebootArgument,   config_parse_string,                0,                             offsetof(Unit, job_timeout_reboot_arg)
diff --git a/src/core/manager.h b/src/core/manager.h
index 38d2770e97..21307bb517 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -141,8 +141,6 @@ struct Manager {
 
         sd_event_source *jobs_in_progress_event_source;
 
-        unsigned n_snapshots;
-
         LookupPaths lookup_paths;
         Set *unit_path_cache;
 
diff --git a/src/core/scope.c b/src/core/scope.c
index 6bacb226e8..c83530a1b0 100644
--- a/src/core/scope.c
+++ b/src/core/scope.c
@@ -54,7 +54,6 @@ static void scope_init(Unit *u) {
         s->timeout_stop_usec = u->manager->default_timeout_stop_usec;
 
         UNIT(s)->ignore_on_isolate = true;
-        UNIT(s)->ignore_on_snapshot = true;
 }
 
 static void scope_done(Unit *u) {
diff --git a/src/core/service.c b/src/core/service.c
index 586eddd99a..74bbadd3ff 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -2365,14 +2365,6 @@ static bool service_check_gc(Unit *u) {
         return false;
 }
 
-_pure_ static bool service_check_snapshot(Unit *u) {
-        Service *s = SERVICE(u);
-
-        assert(s);
-
-        return s->socket_fd < 0;
-}
-
 static int service_retry_pid_file(Service *s) {
         int r;
 
@@ -3294,7 +3286,6 @@ const UnitVTable service_vtable = {
         .sub_state_to_string = service_sub_state_to_string,
 
         .check_gc = service_check_gc,
-        .check_snapshot = service_check_snapshot,
 
         .sigchld_event = service_sigchld_event,
 
diff --git a/src/core/snapshot.c b/src/core/snapshot.c
deleted file mode 100644
index ba3135f401..0000000000
--- a/src/core/snapshot.c
+++ /dev/null
@@ -1,303 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-/***
-  This file is part of systemd.
-
-  Copyright 2010 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 <errno.h>
-
-#include "alloc-util.h"
-#include "bus-common-errors.h"
-#include "dbus-snapshot.h"
-#include "parse-util.h"
-#include "parse-util.h"
-#include "snapshot.h"
-#include "string-util.h"
-#include "unit-name.h"
-#include "unit.h"
-
-static const UnitActiveState state_translation_table[_SNAPSHOT_STATE_MAX] = {
-        [SNAPSHOT_DEAD] = UNIT_INACTIVE,
-        [SNAPSHOT_ACTIVE] = UNIT_ACTIVE
-};
-
-static void snapshot_init(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(UNIT(s)->load_state == UNIT_STUB);
-
-        UNIT(s)->ignore_on_isolate = true;
-        UNIT(s)->ignore_on_snapshot = true;
-        UNIT(s)->allow_isolate = true;
-}
-
-static void snapshot_set_state(Snapshot *s, SnapshotState state) {
-        SnapshotState old_state;
-        assert(s);
-
-        old_state = s->state;
-        s->state = state;
-
-        if (state != old_state)
-                log_unit_debug(UNIT(s), "Changed %s -> %s", snapshot_state_to_string(old_state), snapshot_state_to_string(state));
-
-        unit_notify(UNIT(s), state_translation_table[old_state], state_translation_table[state], true);
-}
-
-static int snapshot_load(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(u);
-        assert(u->load_state == UNIT_STUB);
-
-        /* Make sure that only snapshots created via snapshot_create()
-         * can be loaded */
-        if (!u->transient && UNIT(s)->manager->n_reloading <= 0)
-                return -ENOENT;
-
-        u->load_state = UNIT_LOADED;
-        return 0;
-}
-
-static int snapshot_coldplug(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(s->state == SNAPSHOT_DEAD);
-
-        if (s->deserialized_state != s->state)
-                snapshot_set_state(s, s->deserialized_state);
-
-        return 0;
-}
-
-static void snapshot_dump(Unit *u, FILE *f, const char *prefix) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(f);
-
-        fprintf(f,
-                "%sSnapshot State: %s\n"
-                "%sClean Up: %s\n",
-                prefix, snapshot_state_to_string(s->state),
-                prefix, yes_no(s->cleanup));
-}
-
-static int snapshot_start(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(s->state == SNAPSHOT_DEAD);
-
-        snapshot_set_state(s, SNAPSHOT_ACTIVE);
-
-        if (s->cleanup)
-                unit_add_to_cleanup_queue(u);
-
-        return 1;
-}
-
-static int snapshot_stop(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(s->state == SNAPSHOT_ACTIVE);
-
-        snapshot_set_state(s, SNAPSHOT_DEAD);
-        return 1;
-}
-
-static int snapshot_serialize(Unit *u, FILE *f, FDSet *fds) {
-        Snapshot *s = SNAPSHOT(u);
-        Unit *other;
-        Iterator i;
-
-        assert(s);
-        assert(f);
-        assert(fds);
-
-        unit_serialize_item(u, f, "state", snapshot_state_to_string(s->state));
-        unit_serialize_item(u, f, "cleanup", yes_no(s->cleanup));
-        SET_FOREACH(other, u->dependencies[UNIT_WANTS], i)
-                unit_serialize_item(u, f, "wants", other->id);
-
-        return 0;
-}
-
-static int snapshot_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
-        Snapshot *s = SNAPSHOT(u);
-        int r;
-
-        assert(u);
-        assert(key);
-        assert(value);
-        assert(fds);
-
-        if (streq(key, "state")) {
-                SnapshotState state;
-
-                state = snapshot_state_from_string(value);
-                if (state < 0)
-                        log_unit_debug(u, "Failed to parse state value: %s", value);
-                else
-                        s->deserialized_state = state;
-
-        } else if (streq(key, "cleanup")) {
-
-                r = parse_boolean(value);
-                if (r < 0)
-                        log_unit_debug(u, "Failed to parse cleanup value: %s", value);
-                else
-                        s->cleanup = r;
-
-        } else if (streq(key, "wants")) {
-
-                r = unit_add_two_dependencies_by_name(u, UNIT_AFTER, UNIT_WANTS, value, NULL, true);
-                if (r < 0)
-                        return r;
-        } else
-                log_unit_debug(u, "Unknown serialization key: %s", key);
-
-        return 0;
-}
-
-_pure_ static UnitActiveState snapshot_active_state(Unit *u) {
-        assert(u);
-
-        return state_translation_table[SNAPSHOT(u)->state];
-}
-
-_pure_ static const char *snapshot_sub_state_to_string(Unit *u) {
-        assert(u);
-
-        return snapshot_state_to_string(SNAPSHOT(u)->state);
-}
-
-int snapshot_create(Manager *m, const char *name, bool cleanup, sd_bus_error *e, Snapshot **_s) {
-        _cleanup_free_ char *n = NULL;
-        Unit *other, *u = NULL;
-        Iterator i;
-        int r;
-        const char *k;
-
-        assert(m);
-        assert(_s);
-
-        if (name) {
-                if (!unit_name_is_valid(name, UNIT_NAME_PLAIN))
-                        return sd_bus_error_setf(e, SD_BUS_ERROR_INVALID_ARGS, "Unit name %s is not valid.", name);
-
-                if (!endswith(name, ".snapshot"))
-                        return sd_bus_error_setf(e, SD_BUS_ERROR_INVALID_ARGS, "Unit name %s lacks snapshot suffix.", name);
-
-                if (manager_get_unit(m, name))
-                        return sd_bus_error_setf(e, BUS_ERROR_UNIT_EXISTS, "Snapshot %s exists already.", name);
-
-        } else {
-
-                for (;;) {
-                        if (asprintf(&n, "snapshot-%u.snapshot", ++ m->n_snapshots) < 0)
-                                return -ENOMEM;
-
-                        if (!manager_get_unit(m, n)) {
-                                name = n;
-                                break;
-                        }
-
-                        n = mfree(n);
-                }
-        }
-
-        r = manager_load_unit_prepare(m, name, NULL, e, &u);
-        if (r < 0)
-                goto fail;
-
-        u->transient = true;
-        manager_dispatch_load_queue(m);
-        assert(u->load_state == UNIT_LOADED);
-
-        HASHMAP_FOREACH_KEY(other, k, m->units, i) {
-
-                if (other->ignore_on_snapshot ||
-                    other->transient)
-                        continue;
-
-                if (k != other->id)
-                        continue;
-
-                if (UNIT_VTABLE(other)->check_snapshot)
-                        if (!UNIT_VTABLE(other)->check_snapshot(other))
-                            continue;
-
-                if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
-                        continue;
-
-                r = unit_add_two_dependencies(u, UNIT_AFTER, UNIT_WANTS, other, true);
-                if (r < 0)
-                        goto fail;
-        }
-
-        SNAPSHOT(u)->cleanup = cleanup;
-        *_s = SNAPSHOT(u);
-
-        log_unit_info(u, "Created snapshot.");
-
-        return 0;
-
-fail:
-        if (u)
-                unit_add_to_cleanup_queue(u);
-
-        return r;
-}
-
-void snapshot_remove(Snapshot *s) {
-        assert(s);
-
-        log_unit_info(UNIT(s), "Removing snapshot.");
-
-        unit_add_to_cleanup_queue(UNIT(s));
-}
-
-const UnitVTable snapshot_vtable = {
-        .object_size = sizeof(Snapshot),
-
-        .no_alias = true,
-        .no_instances = true,
-        .no_gc = true,
-
-        .init = snapshot_init,
-        .load = snapshot_load,
-
-        .coldplug = snapshot_coldplug,
-
-        .dump = snapshot_dump,
-
-        .start = snapshot_start,
-        .stop = snapshot_stop,
-
-        .serialize = snapshot_serialize,
-        .deserialize_item = snapshot_deserialize_item,
-
-        .active_state = snapshot_active_state,
-        .sub_state_to_string = snapshot_sub_state_to_string,
-
-        .bus_vtable = bus_snapshot_vtable
-};
diff --git a/src/core/snapshot.h b/src/core/snapshot.h
deleted file mode 100644
index bd52dea408..0000000000
--- a/src/core/snapshot.h
+++ /dev/null
@@ -1,39 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-#pragma once
-
-/***
-  This file is part of systemd.
-
-  Copyright 2010 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/>.
-***/
-
-typedef struct Snapshot Snapshot;
-
-#include "unit.h"
-
-struct Snapshot {
-        Unit meta;
-
-        SnapshotState state, deserialized_state;
-
-        bool cleanup;
-};
-
-extern const UnitVTable snapshot_vtable;
-
-int snapshot_create(Manager *m, const char *name, bool cleanup, sd_bus_error *e, Snapshot **s);
-void snapshot_remove(Snapshot *s);
diff --git a/src/core/unit.c b/src/core/unit.c
index 6c130d4cd1..4def96b0c1 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -63,7 +63,6 @@ const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX] = {
         [UNIT_SOCKET] = &socket_vtable,
         [UNIT_BUSNAME] = &busname_vtable,
         [UNIT_TARGET] = &target_vtable,
-        [UNIT_SNAPSHOT] = &snapshot_vtable,
         [UNIT_DEVICE] = &device_vtable,
         [UNIT_MOUNT] = &mount_vtable,
         [UNIT_AUTOMOUNT] = &automount_vtable,
@@ -998,15 +997,13 @@ void unit_dump(Unit *u, FILE *f, const char *prefix) {
                         "%s\tRefuseManualStop: %s\n"
                         "%s\tDefaultDependencies: %s\n"
                         "%s\tOnFailureJobMode: %s\n"
-                        "%s\tIgnoreOnIsolate: %s\n"
-                        "%s\tIgnoreOnSnapshot: %s\n",
+                        "%s\tIgnoreOnIsolate: %s\n",
                         prefix, yes_no(u->stop_when_unneeded),
                         prefix, yes_no(u->refuse_manual_start),
                         prefix, yes_no(u->refuse_manual_stop),
                         prefix, yes_no(u->default_dependencies),
                         prefix, job_mode_to_string(u->on_failure_job_mode),
-                        prefix, yes_no(u->ignore_on_isolate),
-                        prefix, yes_no(u->ignore_on_snapshot));
+                        prefix, yes_no(u->ignore_on_isolate));
 
                 if (UNIT_VTABLE(u)->dump)
                         UNIT_VTABLE(u)->dump(u, f, prefix2);
diff --git a/src/core/unit.h b/src/core/unit.h
index 6f775c5ce1..6455f201b4 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -203,9 +203,6 @@ struct Unit {
         /* Ignore this unit when isolating */
         bool ignore_on_isolate;
 
-        /* Ignore this unit when snapshotting */
-        bool ignore_on_snapshot;
-
         /* Did the last condition check succeed? */
         bool condition_result;
         bool assert_result;
@@ -248,7 +245,6 @@ typedef enum UnitSetPropertiesMode {
 #include "socket.h"
 #include "busname.h"
 #include "target.h"
-#include "snapshot.h"
 #include "device.h"
 #include "automount.h"
 #include "swap.h"
@@ -343,9 +339,6 @@ struct UnitVTable {
          * shall release its runtime resources */
         void (*release_resources)(Unit *u);
 
-        /* Return true when this unit is suitable for snapshotting */
-        bool (*check_snapshot)(Unit *u);
-
         /* Invoked on every child that died */
         void (*sigchld_event)(Unit *u, pid_t pid, int code, int status);
 
@@ -443,7 +436,6 @@ DEFINE_CAST(SERVICE, Service);
 DEFINE_CAST(SOCKET, Socket);
 DEFINE_CAST(BUSNAME, BusName);
 DEFINE_CAST(TARGET, Target);
-DEFINE_CAST(SNAPSHOT, Snapshot);
 DEFINE_CAST(DEVICE, Device);
 DEFINE_CAST(MOUNT, Mount);
 DEFINE_CAST(AUTOMOUNT, Automount);
diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 70871cf3e6..3918d7e79b 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -4905,102 +4905,6 @@ static int set_property(int argc, char *argv[], void *userdata) {
         return 0;
 }
 
-static int snapshot(int argc, char *argv[], void *userdata) {
-        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
-        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-        _cleanup_free_ char *n = NULL, *id = NULL;
-        const char *path;
-        sd_bus *bus;
-        int r;
-
-        polkit_agent_open_if_enabled();
-
-        if (argc > 1) {
-                r = unit_name_mangle_with_suffix(argv[1], UNIT_NAME_NOGLOB, ".snapshot", &n);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to generate unit name: %m");
-        } else {
-                n = strdup("");
-                if (!n)
-                        return log_oom();
-        }
-
-        r = acquire_bus(BUS_MANAGER, &bus);
-        if (r < 0)
-                return r;
-
-        r = sd_bus_call_method(
-                        bus,
-                        "org.freedesktop.systemd1",
-                        "/org/freedesktop/systemd1",
-                        "org.freedesktop.systemd1.Manager",
-                        "CreateSnapshot",
-                        &error,
-                        &reply,
-                        "sb", n, false);
-        if (r < 0)
-                return log_error_errno(r, "Failed to create snapshot: %s", bus_error_message(&error, r));
-
-        r = sd_bus_message_read(reply, "o", &path);
-        if (r < 0)
-                return bus_log_parse_error(r);
-
-        r = sd_bus_get_property_string(
-                        bus,
-                        "org.freedesktop.systemd1",
-                        path,
-                        "org.freedesktop.systemd1.Unit",
-                        "Id",
-                        &error,
-                        &id);
-        if (r < 0)
-                return log_error_errno(r, "Failed to get ID of snapshot: %s", bus_error_message(&error, r));
-
-        if (!arg_quiet)
-                puts(id);
-
-        return 0;
-}
-
-static int delete_snapshot(int argc, char *argv[], void *userdata) {
-        _cleanup_strv_free_ char **names = NULL;
-        sd_bus *bus;
-        char **name;
-        int r;
-
-        polkit_agent_open_if_enabled();
-
-        r = acquire_bus(BUS_MANAGER, &bus);
-        if (r < 0)
-                return r;
-
-        r = expand_names(bus, strv_skip(argv, 1), ".snapshot", &names);
-        if (r < 0)
-                return log_error_errno(r, "Failed to expand names: %m");
-
-        STRV_FOREACH(name, names) {
-                _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
-                int q;
-
-                q = sd_bus_call_method(
-                                bus,
-                                "org.freedesktop.systemd1",
-                                "/org/freedesktop/systemd1",
-                                "org.freedesktop.systemd1.Manager",
-                                "RemoveSnapshot",
-                                &error,
-                                NULL,
-                                "s", *name);
-                if (q < 0) {
-                        log_error_errno(q, "Failed to remove snapshot %s: %s", *name, bus_error_message(&error, q));
-                        if (r == 0)
-                                r = q;
-                }
-        }
-
-        return r;
-}
-
 static int daemon_reload(int argc, char *argv[], void *userdata) {
         _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
         const char *method;
@@ -6381,9 +6285,6 @@ static void systemctl_help(void) {
                "Job Commands:\n"
                "  list-jobs [PATTERN...]          List jobs\n"
                "  cancel [JOB...]                 Cancel all, one, or more jobs\n\n"
-               "Snapshot Commands:\n"
-               "  snapshot [NAME]                 Create a snapshot\n"
-               "  delete NAME...                  Remove one or more snapshots\n\n"
                "Environment Commands:\n"
                "  show-environment                Dump environment\n"
                "  set-environment NAME=VALUE...   Set one or more environment variables\n"
@@ -6526,11 +6427,6 @@ static void help_states(void) {
                 puts(slice_state_to_string(i));
 
         if (!arg_no_legend)
-                puts("\nAvailable snapshot unit substates:");
-        for (i = 0; i < _SNAPSHOT_STATE_MAX; i++)
-                puts(snapshot_state_to_string(i));
-
-        if (!arg_no_legend)
                 puts("\nAvailable socket unit substates:");
         for (i = 0; i < _SOCKET_STATE_MAX; i++)
                 puts(socket_state_to_string(i));
@@ -7460,8 +7356,6 @@ static int systemctl_main(int argc, char *argv[]) {
                 { "cat",                   2,        VERB_ANY, 0,            cat               },
                 { "status",                VERB_ANY, VERB_ANY, 0,            show              },
                 { "help",                  VERB_ANY, VERB_ANY, 0,            show              },
-                { "snapshot",              VERB_ANY, 2,        0,            snapshot          },
-                { "delete",                2,        VERB_ANY, 0,            delete_snapshot   },
                 { "daemon-reload",         VERB_ANY, 1,        0,            daemon_reload     },
                 { "daemon-reexec",         VERB_ANY, 1,        0,            daemon_reload     },
                 { "show-environment",      VERB_ANY, 1,        0,            show_environment  },
diff --git a/src/test/test-tables.c b/src/test/test-tables.c
index ed4abdbf12..da27cde3da 100644
--- a/src/test/test-tables.c
+++ b/src/test/test-tables.c
@@ -39,7 +39,6 @@
 #include "scope.h"
 #include "service.h"
 #include "slice.h"
-#include "snapshot.h"
 #include "socket-util.h"
 #include "socket.h"
 #include "swap.h"
@@ -98,7 +97,6 @@ int main(int argc, char **argv) {
         test_table(service_state, SERVICE_STATE);
         test_table(service_type, SERVICE_TYPE);
         test_table(slice_state, SLICE_STATE);
-        test_table(snapshot_state, SNAPSHOT_STATE);
         test_table(socket_address_bind_ipv6_only, SOCKET_ADDRESS_BIND_IPV6_ONLY);
         test_table(socket_exec_command, SOCKET_EXEC_COMMAND);
         test_table(socket_result, SOCKET_RESULT);