Ticket #8889: 0001-Code-to-reproduce-block-cache-problem-with-discarded.patch

src/add-ons/kernel/file_systems/bfs/kernel_interface.cpp

@@ -623 +623 @@
     Volume* volume = (Volume*)_volume->private_volume;
 
     switch (cmd) {
+        case 56743:
+        {
+            const char string1[] = "wrote in transaction";
+            const char string2[] = "wrote with write_pos";
+
+            // pick a block, any block (preferrably one you're not too fond of)
+            off_t block = 6000;
+
+            // write something to it
+            Transaction transaction(volume, 0);
+
+            CachedBlock cached(volume);
+            uint8* cachedData = cached.SetToWritable(transaction, block);
+            memcpy(cachedData, string1, sizeof(string1));
+            cached.Unset();
+
+            transaction.Done();
+
+            // if this is uncommented, string2 is read
+            //volume->GetJournal(0)->FlushLogAndBlocks();
+
+            // this is supposed to be equivalent to freeing the block and
+            // allocating it again
+            block_cache_discard(volume->BlockCache(), block, 1);
+
+            // write something else to the block
+            write_pos(volume->Device(), block << volume->BlockShift(),
+                string2, sizeof(string2));
+
+            // read the block (prints "wrote in transaction")
+            cached.SetTo(block);
+            INFORM(("string read from block: \"%s\"\n", cached.Block()));
+
+            return B_OK;
+        }
         case BFS_IOCTL_VERSION:
         {
             uint32 version = 0x10000;