swap: major rework, use /sbin/swapon for setting up swaps, fix merging of aliased swap disks

TODO

@@ -30,8 +30,6 @@
 
 * set_put(), hashmap_put() return values check. i.e. == 0 doesn't free()!
 
-* fix merging in .swap units
-
 * chkconfig/systemd-install glue
 
 * io priority during initialization
@@ -80,8 +78,6 @@
 
 * beefed up tmpwatch that reads tmpfiles.d
 
-* use /sbin/swapon
-
 * enable syslog.socket by default, activating our kmsg bridge
 
 * when processes remain in a service even though the start command failed enter active

src/device.c

@@ -188,10 +188,6 @@ static int device_update_unit(Manager *m, struct udev_device *dev, const char *p
         if ((r = device_find_escape_name(m, path, &u)) < 0)
                 return r;
 
-        /* If a different unit already claimed this name then let's do
-         * nothing. This can happen for example when two disks with
-         * the same label are plugged in, and which hence try to get
-         * conflicting symlinks in /dev/disk/by-label/xxxx */
         if (u && DEVICE(u)->sysfs && !path_equal(DEVICE(u)->sysfs, sysfs))
                 return -EEXIST;
 

src/list.h

@@ -116,4 +116,10 @@
 #define LIST_FOREACH_SAFE(name,i,n,head)                                \
         for ((i) = (head); (i) && (((n) = (i)->name##_next), 1); (i) = (n))
 
+#define LIST_FOREACH_BEFORE(name,i,p)                                   \
+        for ((i) = (p)->name##_prev; (i); (i) = (i)->name##_prev)
+
+#define LIST_FOREACH_AFTER(name,i,p)                                    \
+        for ((i) = (p)->name##_next; (i); (i) = (i)->name##_next)
+
 #endif

src/manager.c

@@ -2217,6 +2217,9 @@ int manager_loop(Manager *m) {
                 if (manager_dispatch_dbus_queue(m) > 0)
                         continue;
 
+                if (swap_dispatch_reload(m) > 0)
+                        continue;
+
                 if ((n = epoll_wait(m->epoll_fd, &event, 1, -1)) < 0) {
 
                         if (errno == EINTR)

src/manager.h

@@ -155,6 +155,8 @@ struct Manager {
 
         /* Data specific to the swap filesystem */
         FILE *proc_swaps;
+        Hashmap *swaps_by_proc_swaps;
+        bool request_reload;
 
         /* Data specific to the D-Bus subsystem */
         DBusConnection *api_bus, *system_bus;

src/swap.h

@@ -29,12 +29,25 @@ typedef struct Swap Swap;
 
 typedef enum SwapState {
         SWAP_DEAD,
+        SWAP_ACTIVATING,
         SWAP_ACTIVE,
+        SWAP_DEACTIVATING,
+        SWAP_ACTIVATING_SIGTERM,
+        SWAP_ACTIVATING_SIGKILL,
+        SWAP_DEACTIVATING_SIGTERM,
+        SWAP_DEACTIVATING_SIGKILL,
         SWAP_FAILED,
         _SWAP_STATE_MAX,
         _SWAP_STATE_INVALID = -1
 } SwapState;
 
+typedef enum SwapExecCommand {
+        SWAP_EXEC_ACTIVATE,
+        SWAP_EXEC_DEACTIVATE,
+        _SWAP_EXEC_COMMAND_MAX,
+        _SWAP_EXEC_COMMAND_INVALID = -1
+} SwapExecCommand;
+
 typedef struct SwapParameters {
         char *what;
         int priority;
@@ -46,27 +59,55 @@ typedef struct SwapParameters {
 struct Swap {
         Meta meta;
 
+        char *what;
+
         SwapParameters parameters_etc_fstab;
         SwapParameters parameters_proc_swaps;
         SwapParameters parameters_fragment;
 
-        char *what;
-
-        SwapState state, deserialized_state;
-
         bool from_etc_fstab:1;
         bool from_proc_swaps:1;
         bool from_fragment:1;
+
+        bool failure:1;
+
+        /* Used while looking for swaps that vanished or got added
+         * from/to /proc/swaps */
+        bool is_active:1;
+        bool just_activated:1;
+
+        usec_t timeout_usec;
+
+        ExecCommand exec_command[_SWAP_EXEC_COMMAND_MAX];
+        ExecContext exec_context;
+
+        SwapState state, deserialized_state;
+
+        ExecCommand* control_command;
+        SwapExecCommand control_command_id;
+        pid_t control_pid;
+
+        Watch timer_watch;
+
+        /* In order to be able to distuingish dependencies on
+        different device nodes we might end up creating multiple
+        devices for the same swap. We chain them up here. */
+
+        LIST_FIELDS(struct Swap, same_proc_swaps);
 };
 
 extern const UnitVTable swap_vtable;
 
-int swap_add_one(Manager *m, const char *what, int prio, bool no_auto, bool no_fail, bool handle, bool from_proc_swap);
+int swap_add_one(Manager *m, const char *what, const char *what_proc_swaps, int prio, bool no_auto, bool no_fail, bool handle, bool set_flags);
 
 int swap_add_one_mount_link(Swap *s, Mount *m);
 
+int swap_dispatch_reload(Manager *m);
+
 const char* swap_state_to_string(SwapState i);
 SwapState swap_state_from_string(const char *s);
 
+const char* swap_exec_command_to_string(SwapExecCommand i);
+SwapExecCommand swap_exec_command_from_string(const char *s);
 
 #endif

src/unit.c

@@ -376,7 +376,6 @@ void unit_free(Unit *u) {
         set_free_free(u->meta.names);
 
         free(u->meta.instance);
-
         free(u);
 }