verity: remove checks for error states

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 664 matching lines @@
         return 0;
 }
 
 /* dm_bht_verify_path
  * Verifies the path from block_index to depth=0. Returns 0 on ok.
  */
 static int dm_bht_verify_path(struct dm_bht *bht, unsigned int block_index)
 {
         unsigned int depth = bht->depth - 1;
         struct dm_bht_entry *entry = dm_bht_get_entry(bht, depth, block_index);
+        int state = atomic_read(&entry->state);
 
-        while (depth > 0) {
+        while (depth > 0 && state != DM_BHT_ENTRY_VERIFIED) {
                 u8 digest[DM_BHT_MAX_DIGEST_SIZE];
                 struct dm_bht_entry *parent;
                 struct page *page;
                 u8 *node;
-                int state;
-
-                DMDEBUG("verify_path for b=%u on d=%d", block_index, depth);
-                /* TODO(msb,wad): would be nice to avoid two atomic reads */
-                state = atomic_read(&entry->state);
-                if (state == DM_BHT_ENTRY_VERIFIED) {
-                        DMDEBUG("verify_path node %u is verified to root",
-                                block_index);
-                        depth++; /* avoid an extra cmpxchg */
-                        break;
-                } else if (state <= DM_BHT_ENTRY_ERROR) {
-                        DMCRIT("entry(d=%u,b=%u) is in an error state: %d",
-                               depth, block_index, state);
-                        DMCRIT("verification is not possible");
-                        goto mismatch;
-                } else if (state <= DM_BHT_ENTRY_PENDING) {
-                        DMERR("entry not ready for verify: d=%u,b=%u",
-                              depth, block_index);
-                        goto mismatch;
-                }
 
                 /* We need to check that this entry matches the expected
                  * hash in the parent->nodes.
                  */
                 parent = dm_bht_get_entry(bht, depth - 1, block_index);
+                state = atomic_read(&parent->state);
                 /* 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(&parent->state) < DM_BHT_ENTRY_READY);
+                BUG_ON(state < DM_BHT_ENTRY_READY);
                 node = dm_bht_get_node(bht, parent, depth, block_index);
                 page = virt_to_page(entry->nodes);
 
                 if (dm_bht_compute_hash(bht, page, digest) ||
-                    dm_bht_compare_hash(bht, digest, node)) {
-                        DMERR("failed to verify entry's hash against parent "
-                              "(d=%u,bi=%u)", depth, block_index);
+                    dm_bht_compare_hash(bht, digest, node))
                         goto mismatch;
-                }
 
                 entry = parent;
                 depth--;
         }
+
         /* Mark path to leaf as verified. */
-        for (; depth < bht->depth; depth++) {
+        for (depth++; depth < bht->depth; depth++) {
                 entry = dm_bht_get_entry(bht, depth, block_index);
                 atomic_cmpxchg(&entry->state,
                                DM_BHT_ENTRY_READY,
                                DM_BHT_ENTRY_VERIFIED);
         }
 
+        DMDEBUG("verify_path: node %u is verified to root", block_index);
         return 0;
 
 mismatch:
+        DMERR("verify_path: failed to verify hash against parent (d=%u,bi=%u)",
+              depth, block_index);
         return DM_BHT_ENTRY_ERROR_MISMATCH;
 }
 
 /**
  * dm_bht_store_block - sets a given block's hash in the tree
  * @bht:        pointer to a dm_bht_create()d bht
  * @block_index:numeric index of the block in the tree
  * @digest:     array of u8s containing the digest of length @bht->digest_size
  *
  * Returns 0 on success, >0 when data is pending, and <0 when a IO or other
@@ skipping 476 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);