MDEV-30657 InnoDB: Not applying UNDO_APPEND due to corruption

This almost completely reverts
commit acd23da and
retains a safe optimization:

recv_sys_t::parse(): Remove any old redo log records for the
truncated tablespace, to free up memory earlier.
If recovery consists of multiple batches, then recv_sys_t::apply()
will must invoke recv_sys_t::trim() again to avoid wrongly
applying old log records to an already truncated undo tablespace.

storage/innobase/include/log0recv.h

@@ -266,9 +266,15 @@ struct recv_sys_t
   @param lsn     log sequence number of the shrink operation */
   inline void trim(const page_id_t page_id, lsn_t lsn);
 
-  /** Truncated undo tablespace size for which truncate has been logged
-  (indexed by page_id_t::space() - srv_undo_space_id_start), or 0 */
-  unsigned truncated_undo_spaces[127];
+  /** Undo tablespaces for which truncate has been logged
+  (indexed by page_id_t::space() - srv_undo_space_id_start) */
+  struct trunc
+  {
+    /** log sequence number of FILE_CREATE, or 0 if none */
+    lsn_t lsn;
+    /** truncated size of the tablespace, or 0 if not truncated */
+    unsigned pages;
+  } truncated_undo_spaces[127];
 
 public:
   /** The contents of the doublewrite buffer */

storage/innobase/log/log0recv.cc

@@ -1952,7 +1952,8 @@ bool recv_sys_t::parse(lsn_t checkpoint_lsn, store_t *store, bool apply)
           /* The entire undo tablespace will be reinitialized by
           innodb_undo_log_truncate=ON. Discard old log for all pages. */
           trim({space_id, 0}, recovered_lsn);
-          truncated_undo_spaces[space_id - srv_undo_space_id_start]= page_no;
+          truncated_undo_spaces[space_id - srv_undo_space_id_start]=
+            { recovered_lsn, page_no };
           if (undo_space_trunc)
             undo_space_trunc(space_id);
 #endif
@@ -2677,15 +2678,22 @@ void recv_sys_t::apply(bool last_batch)
 
     for (auto id= srv_undo_tablespaces_open; id--;)
     {
-      if (unsigned pages= truncated_undo_spaces[id])
+      const trunc& t= truncated_undo_spaces[id];
+      if (t.lsn)
       {
-        if (fil_space_t *space= fil_space_get(id + srv_undo_space_id_start))
+        /* The entire undo tablespace will be reinitialized by
+        innodb_undo_log_truncate=ON. Discard old log for all pages.
+        Even though we recv_sys_t::parse() already invoked trim(),
+        this will be needed in case recovery consists of multiple batches
+        (there was an invocation with !last_batch). */
+        trim({id + srv_undo_space_id_start, 0}, t.lsn);
+        if (fil_space_t *space = fil_space_get(id + srv_undo_space_id_start))
         {
           ut_ad(UT_LIST_GET_LEN(space->chain) == 1);
           fil_node_t *file= UT_LIST_GET_FIRST(space->chain);
           ut_ad(file->is_open());
           os_file_truncate(file->name, file->handle,
-                           os_offset_t{pages} << srv_page_size_shift, true);
+                           os_offset_t{t.pages} << srv_page_size_shift, true);
         }
       }
     }