CheckBlocks
status_t status = CheckBlocks(fVolume->ToBlock(run), run.Length(),
if (allocator->CheckBlocks(0, reservedBlocks) != B_OK) {
status_t CheckBlocks(off_t start, off_t length,
status = allocator.CheckBlocks(block, end - block, true, &firstMissing);
status = allocator.CheckBlocks(firstMissing, end - firstMissing, false,