Fix wal tag safety issues, and add debug assertion that we are reading the proper frames

core/storage/pager.rs

@@ -287,6 +287,7 @@ impl Page {
         self.get().wal_tag.store(TAG_UNSET, Ordering::Release)
     }
 
+    #[inline]
     pub fn is_valid_for_checkpoint(&self, target_frame: u64, seq: u32) -> bool {
         let (f, s) = self.wal_tag_pair();
         f == target_frame && s == seq && !self.is_dirty()

core/storage/sqlite3_ondisk.rs

@@ -912,6 +912,9 @@ pub fn finish_read_page(page_idx: usize, buffer_ref: Arc<Buffer>, page: PageRef)
         page.get().contents.replace(inner);
         page.clear_locked();
         page.set_loaded();
+        // we set the wal tag only when reading page from log, or in allocate_page,
+        // we clear it here for safety in case page is being re-loaded.
+        page.clear_wal_tag();
     }
 }
 

core/storage/wal.rs

@@ -1375,12 +1375,6 @@ impl WalFile {
         shared: Arc<UnsafeCell<WalFileShared>>,
         buffer_pool: Arc<BufferPool>,
     ) -> Self {
-        let checkpoint_page = Arc::new(Page::new(0));
-        let buffer = buffer_pool.get_page();
-        {
-            checkpoint_page.get().contents = Some(PageContent::new(0, Arc::new(buffer)));
-        }
-
         let header = unsafe { shared.get().as_mut().unwrap().wal_header.lock() };
         let last_checksum = unsafe { (*shared.get()).last_checksum };
         let disable_checkpoint_cache =
@@ -1813,7 +1807,7 @@ impl WalFile {
     /// Must be invoked while writer and checkpoint locks are still held.
     fn restart_log(&mut self, mode: CheckpointMode) -> Result<()> {
         turso_assert!(
-            matches!(mode, CheckpointMode::Restart | CheckpointMode::Truncate),
+            mode.should_restart_log(),
             "CheckpointMode must be Restart or Truncate"
         );
         turso_assert!(