btree_readahead_hook 3397 fs/btrfs/ctree.h int btree_readahead_hook(struct extent_buffer *eb, int err);
btree_readahead_hook  688 fs/btrfs/disk-io.c 		btree_readahead_hook(eb, ret);
btree_readahead_hook 2803 fs/btrfs/extent_io.c 				btree_readahead_hook(eb, -EIO);