From b4efd8b0d6408a7434ce4da591c5035fa6aea02b Mon Sep 17 00:00:00 2001
From: Thirunarayanan Balathandayuthapani <thiru@mariadb.com>
Date: Wed, 17 May 2023 17:07:24 +0530
Subject: - Removed extent descriptor page from FSP_FREE_FRAG list and reduced
 the FREE_FRAG_N_USED. - Removed the truncated pages from flush list

---
 storage/innobase/fsp/fsp0fsp.cc | 83 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 75 insertions(+), 8 deletions(-)

diff --git a/storage/innobase/fsp/fsp0fsp.cc b/storage/innobase/fsp/fsp0fsp.cc
index e92efac49b7..7fa21716465 100644
--- a/storage/innobase/fsp/fsp0fsp.cc
+++ b/storage/innobase/fsp/fsp0fsp.cc
@@ -3078,18 +3078,19 @@ std::ostream &fseg_header::to_stream(std::ostream &out) const
 @return DB_SUCCESS on success or error code */
 static
 void
-fsp_truncate_free_list(fil_space_t *space, buf_block_t *header,
-                       uint32_t threshold, mtr_t *mtr)
+fsp_truncate_list(fil_space_t *space, buf_block_t *header,
+		  uint16_t hdr_offset, uint32_t threshold,
+		  mtr_t *mtr)
 {
   const uint32_t len= flst_get_len(
-    FSP_HEADER_OFFSET + FSP_FREE + header->page.frame);
+    FSP_HEADER_OFFSET + hdr_offset + header->page.frame);
   if (len == 0)
     return;
 
   buf_block_t *descr_block= nullptr;
   dberr_t err= DB_SUCCESS;
   fil_addr_t addr= flst_get_first(
-    header->page.frame + FSP_HEADER_OFFSET + FSP_FREE);
+    header->page.frame + FSP_HEADER_OFFSET + hdr_offset);
 
   for (uint32_t i= len; i > 0; i--)
   {
@@ -3106,16 +3107,26 @@ fsp_truncate_free_list(fil_space_t *space, buf_block_t *header,
     {
       /* Remove the truncated free list extents */
       err= flst_remove(
-             header, FSP_HEADER_OFFSET + FSP_FREE, descr_block,
+             header, FSP_HEADER_OFFSET + hdr_offset, descr_block,
              static_cast<uint16_t>(descr - descr_block->page.frame
                                    + XDES_FLST_NODE), mtr);
-      space->free_len--;
+      if (hdr_offset == FSP_FREE)
+        space->free_len--;
+      else
+      {
+        uint32_t frag_n_used= mach_read_from_4(
+          FSP_HEADER_OFFSET + FSP_FRAG_N_USED + header->page.frame);
+	frag_n_used-= 2;
+	mtr->write<4>(*header, FSP_HEADER_OFFSET + FSP_FRAG_N_USED
+                      + header->page.frame, frag_n_used);
+      }
     }
 
     addr= flst_get_next_addr(b->page.frame + addr.boffset);
     if (addr.page == FIL_NULL)
-      return;
+      break;
   }
+
   return;
 }
 
@@ -3252,8 +3263,64 @@ dberr_t fsp_tablespace_truncate(fil_space_t *space)
     return err;
   }
 
+  mysql_mutex_lock(&buf_pool.flush_list_mutex);
+  for (buf_page_t *bpage= UT_LIST_GET_LAST(buf_pool.flush_list); bpage; )
+  {
+    ut_ad(bpage->oldest_modification());
+    ut_ad(bpage->in_file());
+
+    buf_page_t *prev= UT_LIST_GET_PREV(list, bpage);
+
+    if (bpage->id().space() == space->id &&
+        bpage->id().page_no() >= last_used_extent &&
+        bpage->oldest_modification() != 1)
+    {
+      ut_ad(bpage->frame);
+      auto block= reinterpret_cast<buf_block_t*>(bpage);
+      if (!bpage->lock.x_lock_try())
+      {
+    rescan:
+        /* Let buf_pool_t::release_freed_page() proceed. */
+        mysql_mutex_unlock(&buf_pool.flush_list_mutex);
+        mysql_mutex_lock(&buf_pool.mutex);
+        mysql_mutex_lock(&buf_pool.flush_list_mutex);
+        mysql_mutex_unlock(&buf_pool.mutex);
+        bpage= UT_LIST_GET_LAST(buf_pool.flush_list);
+        continue;
+      }
+      buf_pool.flush_hp.set(prev);
+      mysql_mutex_unlock(&buf_pool.flush_list_mutex);
+
+#ifdef BTR_CUR_HASH_ADAPT
+      ut_ad(!block->index); /* There is no AHI on undo tablespaces. */
+#endif
+      bpage->fix();
+      ut_ad(!bpage->is_io_fixed());
+      mysql_mutex_lock(&buf_pool.flush_list_mutex);
+
+      if (bpage->oldest_modification() > 1)
+      {
+        bpage->reset_oldest_modification();
+        mtr.memo_push(block, MTR_MEMO_PAGE_X_FIX);
+      }
+      else
+      {
+        bpage->unfix();
+        bpage->lock.x_unlock();
+      }
+
+      if (prev != buf_pool.flush_hp.get())
+        /* Rescan, because we may have lost the position. */
+        goto rescan;
+    }
+
+    bpage= prev;
+  }
+
+  mysql_mutex_unlock(&buf_pool.flush_list_mutex);
   mtr.trim_pages(page_id_t(space->id, last_used_extent));
-  fsp_truncate_free_list(space, header, last_used_extent, &mtr);
+  fsp_truncate_list(space, header, FSP_FREE, last_used_extent, &mtr);
+  fsp_truncate_list(space, header, FSP_FREE_FRAG, last_used_extent, &mtr);
   fsp_xdes_reset(space, last_used_extent, &mtr);
 
   ib::info() <<"Truncating system tablespaces from " << space->size
-- 
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