liveupdate: propagate file deserialization failures

luo_session_deserialize() ignored the return value from
luo_file_deserialize().  As a result, a session could be left partially
restored even though the /dev/liveupdate open path treats deserialization
failures as fatal.

Propagate the error so a failed file deserialization aborts session
deserialization instead of silently continuing.

Link: https://lkml.kernel.org/r/20260325044608.8407-1-leotimmins1974@gmail.com
Link: https://lkml.kernel.org/r/20260325044608.8407-2-leotimmins1974@gmail.com
Fixes: 16cec0d ("liveupdate: luo_session: add ioctls for file preservation")
Signed-off-by: Leo Timmins <leotimmins1974@gmail.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: leotimmins1974

kernel/liveupdate/luo_session.c

@@ -558,8 +558,13 @@ int luo_session_deserialize(void)
 		}
 
 		scoped_guard(mutex, &session->mutex) {
-			luo_file_deserialize(&session->file_set,
-					     &sh->ser[i].file_set_ser);
+			err = luo_file_deserialize(&session->file_set,
+						   &sh->ser[i].file_set_ser);
+		}
+		if (err) {
+			pr_warn("Failed to deserialize files for session [%s] %pe\n",
+				session->name, ERR_PTR(err));
+			return err;
 		}
 	}