Block drivers often attempt to retry requests that fail the first time. This behavior can
lead to a more reliable system and help to avoid data loss. The kernel, however,
sometimes marks requests as not being retryable. Such requests should simply fail as
quickly as possible if they cannot be executed on the first try.
If your driver is considering retrying a failed request, it should first make a call to:
int blk_noretry_request(struct request *req);
If this macro returns a nonzero value, your driver should simply abort the request
with an error code instead of retrying it
