Btrfs: verify csums on read

[deliverable/linux.git] / fs / btrfs / file-item.c

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 5230a44cb19b9eed44ec5e9a82d248454c9e1630..2d2c23ca7cbfd30a872c09de172c3de23fd82db8 100644 (file)
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -57,3 +57,63 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
        ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
        return ret;
 }
+
+int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *root,
+                         u64 objectid, u64 offset,
+                         char *data, size_t len)
+{
+       int ret;
+       struct btrfs_key file_key;
+       struct btrfs_path path;
+       struct btrfs_csum_item *item;
+
+       btrfs_init_path(&path);
+       file_key.objectid = objectid;
+       file_key.offset = offset;
+       file_key.flags = 0;
+       btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+       ret = btrfs_insert_empty_item(trans, root, &path, &file_key,
+                                     BTRFS_CSUM_SIZE);
+       if (ret != 0 && ret != -EEXIST)
+               goto fail;
+       item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
+                             struct btrfs_csum_item);
+       ret = 0;
+       ret = btrfs_csum_data(root, data, len, item->csum);
+       mark_buffer_dirty(path.nodes[0]);
+fail:
+       btrfs_release_path(root, &path);
+       return ret;
+}
+
+int btrfs_csum_verify_file_block(struct btrfs_root *root,
+                                u64 objectid, u64 offset,
+                                char *data, size_t len)
+{
+       int ret;
+       struct btrfs_key file_key;
+       struct btrfs_path path;
+       struct btrfs_csum_item *item;
+       char result[BTRFS_CSUM_SIZE];
+
+       btrfs_init_path(&path);
+       file_key.objectid = objectid;
+       file_key.offset = offset;
+       file_key.flags = 0;
+       btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+       ret = btrfs_search_slot(NULL, root, &file_key, &path, 0, 0);
+       if (ret)
+               goto fail;
+       item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
+                             struct btrfs_csum_item);
+       ret = 0;
+       ret = btrfs_csum_data(root, data, len, result);
+       WARN_ON(ret);
+       if (memcmp(result, item->csum, BTRFS_CSUM_SIZE))
+               ret = 1;
+fail:
+       btrfs_release_path(root, &path);
+       return ret;
+}
+