verity: only requeue if necessary

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 902 matching lines @@
                         }
                         sector += to_sector(PAGE_SIZE);
                 }
         }
 
         return 0;
 }
 EXPORT_SYMBOL(dm_bht_sync);
 
 /**
+ * dm_bht_is_populated - check that entries from disk needed to verify a given
+ *                       block are all ready
+ * @bht:        pointer to a dm_bht_create()d bht
+ * @block_index:specific block data is expected from
+ *
+ * Callers may wish to call dm_bht_is_populated() when checking an io
+ * for which entries were already pending.
+ */
+bool dm_bht_is_populated(struct dm_bht *bht, unsigned int block_index)
+{
+        unsigned int depth;
+
+        if (atomic_read(&bht->root_state) < DM_BHT_ENTRY_READY)
+                return false;
+
+        for (depth = bht->depth - 1; depth > 0; depth--) {
+                struct dm_bht_entry *entry = dm_bht_get_entry(bht, depth,
+                                                              block_index);
+                if (atomic_read(&entry->state) < DM_BHT_ENTRY_READY)
+                        return false;
+        }
+
+        return true;
+}
+EXPORT_SYMBOL(dm_bht_is_populated);
+
+/**
  * dm_bht_populate - reads entries from disk needed to verify a given block
  * @bht:        pointer to a dm_bht_create()d bht
  * @read_cb_ctx:context used for all read_cb calls on this request
  * @block_index:specific block data is expected from
  *
  * Callers may wish to call dm_bht_populate(0) immediately after initialization
  * to start loading in all the level[0] entries.
  */
 int dm_bht_populate(struct dm_bht *bht, void *read_cb_ctx,
                     unsigned int block_index)
@@ skipping 259 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);