CHROMIUM: verity: add BUG in check_block for consistency with verify_path

drivers/md/dm-bht.c

  /*
  * Copyright (C) 2010 The Chromium OS Authors <chromium-os-dev@chromium.org>
  *
  * Device-Mapper block hash tree interface.
  * See Documentation/device-mapper/dm-bht.txt for details.
  *
  * This file is released under the GPL.
  */
 
 #include <asm/atomic.h>
@@ skipping 597 matching lines @@
         /* The leaves contain the block hashes */
         depth = bht->depth - 1;
 
         /* Index into the bottom level.  Each entry in this level contains
          * nodes whose hashes are the direct hashes of one block of data on
          * disk.
          */
         index = block_index >> bht->node_count_shift;
         entry = &bht->levels[depth].entries[index];
 
-        *entry_state = atomic_read(&entry->state);
-        if (*entry_state <= DM_BHT_ENTRY_ERROR) {
-                DMCRIT("leaf entry for block %u is invalid",
-                       block_index);
-                return *entry_state;
-        }
-        if (*entry_state <= DM_BHT_ENTRY_PENDING) {
-                DMERR("leaf data not yet loaded for block %u",
-                      block_index);
-                return 1;
-        }
+        /* This call is only safe if all nodes along the path
+         * are already populated (i.e. READY) via dm_bht_populate.
+         */
+        BUG_ON(atomic_read(&entry->state) < DM_BHT_ENTRY_READY);
 
         /* Index into the entry data */
         index = (block_index % bht->node_count) * bht->digest_size;
         if (memcmp(&entry->nodes[index], digest, bht->digest_size)) {
                 DMCRIT("digest mismatch for block %u", block_index);
                 dm_bht_log_mismatch(bht, &entry->nodes[index], digest);
                 return DM_BHT_ENTRY_ERROR_MISMATCH;
         }
         /* TODO(wad) update bht->block_bitmap here or in the caller */
         return 0;
@@ skipping 655 matching lines @@
                 DMERR("no root digest exists to export");
                 if (available > 0)
                         *hexdigest = 0;
                 return -1;
         }
         dm_bht_bin_to_hex(bht->root_digest, hexdigest, bht->digest_size);
         return 0;
 }
 EXPORT_SYMBOL(dm_bht_root_hexdigest);