homed: add automatic grow/shrink ("rebalancing")

1 files changed, 65 insertions, 2 deletions

diff --git a/src/home/homed-home.c b/src/home/homed-home.c
index 2cc1f8b384..470c7f07f6 100644
--- a/src/home/homed-home.c
+++ b/src/home/homed-home.c
@@ -161,6 +161,7 @@ int home_new(Manager *m, UserRecord *hr, const char *sysfs, Home **ret) {
 
         (void) bus_manager_emit_auto_login_changed(m);
         (void) bus_home_emit_change(home);
+        (void) manager_schedule_rebalance(m, /* immediately= */ false);
 
         if (ret)
                 *ret = TAKE_PTR(home);
@@ -193,6 +194,8 @@ Home *home_free(Home *h) {
 
                 if (h->manager->gc_focus == h)
                         h->manager->gc_focus = NULL;
+
+                (void) manager_schedule_rebalance(h->manager, /* immediately= */ false);
         }
 
         user_record_unref(h->record);
@@ -489,6 +492,7 @@ static void home_set_state(Home *h, HomeState state) {
                  * enqueue it for GC too. */
 
                 home_schedule_operation(h, NULL, NULL);
+                manager_reschedule_rebalance(h->manager);
                 manager_enqueue_gc(h->manager, h);
         }
 }
@@ -727,6 +731,7 @@ static void home_fixate_finish(Home *h, int ret, UserRecord *hr) {
         /* Reset the state to "invalid", which makes home_get_state() test if the image exists and returns
          * HOME_ABSENT vs. HOME_INACTIVE as necessary. */
         home_set_state(h, _HOME_STATE_INVALID);
+        (void) manager_schedule_rebalance(h->manager, /* immediately= */ false);
         return;
 
 fail:
@@ -781,6 +786,9 @@ static void home_activate_finish(Home *h, int ret, UserRecord *hr) {
 finish:
         h->current_operation = operation_result_unref(h->current_operation, r, &error);
         home_set_state(h, _HOME_STATE_INVALID);
+
+        if (r >= 0)
+                (void) manager_schedule_rebalance(h->manager, /* immediately= */ true);
 }
 
 static void home_deactivate_finish(Home *h, int ret, UserRecord *hr) {
@@ -803,6 +811,9 @@ static void home_deactivate_finish(Home *h, int ret, UserRecord *hr) {
 finish:
         h->current_operation = operation_result_unref(h->current_operation, r, &error);
         home_set_state(h, _HOME_STATE_INVALID);
+
+        if (r >= 0)
+                (void) manager_schedule_rebalance(h->manager, /* immediately= */ true);
 }
 
 static void home_remove_finish(Home *h, int ret, UserRecord *hr) {
@@ -841,6 +852,8 @@ static void home_remove_finish(Home *h, int ret, UserRecord *hr) {
 
         /* Unload this record from memory too now. */
         h = home_free(h);
+
+        (void) manager_schedule_rebalance(m, /* immediately= */ true);
         return;
 
 fail:
@@ -885,6 +898,8 @@ static void home_create_finish(Home *h, int ret, UserRecord *hr) {
 
         h->current_operation = operation_result_unref(h->current_operation, 0, NULL);
         home_set_state(h, _HOME_STATE_INVALID);
+
+        (void) manager_schedule_rebalance(h->manager, /* immediately= */ true);
 }
 
 static void home_change_finish(Home *h, int ret, UserRecord *hr) {
@@ -918,6 +933,7 @@ static void home_change_finish(Home *h, int ret, UserRecord *hr) {
         }
 
         log_debug("Change operation of %s completed.", h->user_name);
+        (void) manager_schedule_rebalance(h->manager, /* immediately= */ false);
         r = 0;
 
 finish:
@@ -1683,7 +1699,12 @@ int home_update(Home *h, UserRecord *hr, sd_bus_error *error) {
         return 0;
 }
 
-int home_resize(Home *h, uint64_t disk_size, UserRecord *secret, sd_bus_error *error) {
+int home_resize(Home *h,
+                uint64_t disk_size,
+                UserRecord *secret,
+                bool automatic,
+                sd_bus_error *error) {
+
         _cleanup_(user_record_unrefp) UserRecord *c = NULL;
         HomeState state;
         int r;
@@ -1711,6 +1732,12 @@ int home_resize(Home *h, uint64_t disk_size, UserRecord *secret, sd_bus_error *e
         if (r < 0)
                 return r;
 
+        /* If the user didn't specify any size explicitly and rebalancing is on, then the disk size is
+         * determined by automatic rebalancing and hence not user configured but determined by us and thus
+         * applied anyway. */
+        if (disk_size == UINT64_MAX && h->record->rebalance_weight != REBALANCE_WEIGHT_OFF)
+                return sd_bus_error_set(error, SD_BUS_ERROR_INVALID_ARGS, "Disk size is being determined by automatic disk space rebalancing.");
+
         if (disk_size == UINT64_MAX || disk_size == h->record->disk_size) {
                 if (h->record->disk_size == UINT64_MAX)
                         return sd_bus_error_set(error, SD_BUS_ERROR_INVALID_ARGS, "No disk size to resize to specified.");
@@ -1732,6 +1759,11 @@ int home_resize(Home *h, uint64_t disk_size, UserRecord *secret, sd_bus_error *e
                 if (r < 0)
                         return r;
 
+                /* If user picked an explicit size, then turn off rebalancing, so that we don't undo what user chose */
+                r = user_record_set_rebalance_weight(c, REBALANCE_WEIGHT_OFF);
+                if (r < 0)
+                        return r;
+
                 r = user_record_update_last_changed(c, false);
                 if (r == -ECHRNG)
                         return sd_bus_error_setf(error, BUS_ERROR_HOME_RECORD_MISMATCH, "Record last change time of %s is newer than current time, cannot update.", h->user_name);
@@ -1746,7 +1778,7 @@ int home_resize(Home *h, uint64_t disk_size, UserRecord *secret, sd_bus_error *e
                 c = TAKE_PTR(signed_c);
         }
 
-        r = home_update_internal(h, "resize", c, secret, error);
+        r = home_update_internal(h, automatic ? "resize-auto" : "resize", c, secret, error);
         if (r < 0)
                 return r;
 
@@ -2965,6 +2997,8 @@ static int on_pending(sd_event_source *s, void *userdata) {
         if (r < 0)
                 return log_error_errno(r, "Failed to disable event source: %m");
 
+        /* No operations pending anymore, maybe this is a good time to trigger a rebalancing */
+        manager_reschedule_rebalance(h->manager);
         return 0;
 }
 
@@ -3121,6 +3155,35 @@ int home_wait_for_worker(Home *h) {
         return 1;
 }
 
+bool home_shall_rebalance(Home *h) {
+        HomeState state;
+
+        assert(h);
+
+        /* Determines if the home directory is a candidate for rebalancing */
+
+        if (!user_record_shall_rebalance(h->record))
+                return false;
+
+        state = home_get_state(h);
+        if (!HOME_STATE_SHALL_REBALANCE(state))
+                return false;
+
+        return true;
+}
+
+bool home_is_busy(Home *h) {
+        assert(h);
+
+        if (h->current_operation)
+                return true;
+
+        if (!ordered_set_isempty(h->pending_operations))
+                return true;
+
+        return HOME_STATE_IS_EXECUTING_OPERATION(home_get_state(h));
+}
+
 static const char* const home_state_table[_HOME_STATE_MAX] = {
         [HOME_UNFIXATED]                   = "unfixated",
         [HOME_ABSENT]                      = "absent",