centos man page for blk_rq_check_limits

BLK_RQ_CHECK_LIMITS(9)						   Block Devices					    BLK_RQ_CHECK_LIMITS(9)

NAME
       blk_rq_check_limits - Helper function to check a request for the queue limit

SYNOPSIS
       int blk_rq_check_limits(struct request_queue * q, struct request * rq);

ARGUMENTS
       q
	   the queue

       rq
	   the request being checked

DESCRIPTION
       rq may have been made based on weaker limitations of upper-level queues in request stacking drivers, and it may violate the limitation of
       q. Since the block layer and the underlying device driver trust rq after it is inserted to q, it should be checked against q before the
       insertion using this generic function.

       This function should also be useful for request stacking drivers in some cases below, so export this function. Request stacking drivers
       like request-based dm may change the queue limits while requests are in the queue (e.g. dm's table swapping). Such request stacking drivers
       should check those requests agaist the new queue limits again when they dispatch those requests, although such checkings are also done
       against the old queue limits when submitting requests.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						    BLK_RQ_CHECK_LIMITS(9)