PM: sleep: Call pm_sleep_fs_sync() instead of ksys_sync_helper()

Replace the direct calls to ksys_sync_helper() with the new
pm_sleep_fs_sync() in suspend and hibernation code paths.

This enables the new mechanism allowing the filesystem sync phase
to be interrupted.

Suggested-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Samuel Wu <wusamuel@google.com>
Co-developed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[ rjw: Subject and changelog edits, tags adjustment ]
Link: https://patch.msgid.link/20251119171426.4086783-3-wusamuel@google.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: wusamuel6

kernel/power/hibernate.c

@@ -820,7 +820,10 @@ int hibernate(void)
 	if (error)
 		goto Restore;
 
-	ksys_sync_helper();
+	error = pm_sleep_fs_sync();
+	if (error)
+		goto Notify;
+
 	if (filesystem_freeze_enabled)
 		filesystems_freeze();
 
@@ -892,6 +895,7 @@ int hibernate(void)
 	freezer_test_done = false;
  Exit:
 	filesystems_thaw();
+ Notify:
 	pm_notifier_call_chain(PM_POST_HIBERNATION);
  Restore:
 	pm_restore_console();

kernel/power/suspend.c

@@ -594,7 +594,11 @@ static int enter_state(suspend_state_t state)
 
 	if (sync_on_suspend_enabled) {
 		trace_suspend_resume(TPS("sync_filesystems"), 0, true);
-		ksys_sync_helper();
+
+		error = pm_sleep_fs_sync();
+		if (error)
+			goto Unlock;
+
 		trace_suspend_resume(TPS("sync_filesystems"), 0, false);
 	}
 

kernel/power/user.c

@@ -278,7 +278,9 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		if (data->frozen)
 			break;
 
-		ksys_sync_helper();
+		error = pm_sleep_fs_sync();
+		if (error)
+			break;
 
 		error = freeze_processes();
 		if (error)