Ticket #8889: 0001-Handle-discarded-blocks-in-unflushed-transaction.patch

src/system/kernel/cache/block_cache.cpp

@@ -1840 +1840 @@
         // The block is currently busy_reading - wait and try again later
         wait_for_busy_reading_block(cache, block);
         goto retry;
+    } else if (block->discard) {
+        // The block has been discarded, but the transaction is not yet
+        // flushed. We remove the block from the transaction and discard
+        // it ourselves.
+
+        ASSERT(block->transaction != NULL);
+
+        // Search through the singly linked transaction list, and remove the
+        // block once we find it
+        // TODO: This is slow, but it should be an uncommon operation anyways
+        cached_block** previousLink = &block->transaction->first_block;
+        cached_block* current = block->transaction->first_block;
+
+        while (true) {
+            if (current == block) {
+                // remove the block from its transaction
+                *previousLink = block->transaction_next;
+                block->transaction->num_blocks--;
+                break;
+            }
+
+            previousLink = &current->transaction_next;
+            current = current->transaction_next;
+
+            if (current == NULL) {
+                panic("Discarded block was not in its transaction!");
+                return NULL;
+            }
+        }
+        
+        cache->DiscardBlock(block);
+        goto retry;
     }
 
     if (block->unused) {