centos man page for blk_queue_merge_bvec

BLK_QUEUE_MERGE_BVEC(9) 					   Block Devices					   BLK_QUEUE_MERGE_BVEC(9)

NAME
       blk_queue_merge_bvec - set a merge_bvec function for queue

SYNOPSIS
       void blk_queue_merge_bvec(struct request_queue * q, merge_bvec_fn * mbfn);

ARGUMENTS
       q
	   queue

       mbfn
	   merge_bvec_fn

DESCRIPTION
       Usually queues have static limitations on the max sectors or segments that we can put in a request. Stacking drivers may have some settings
       that are dynamic, and thus we have to query the queue whether it is ok to add a new bio_vec to a bio at a given offset or not. If the block
       device has such limitations, it needs to register a merge_bvec_fn to control the size of bio's sent to it. Note that a block device *must*
       allow a single page to be added to an empty bio. The block device driver may want to use the bio_split function to deal with these bio's.
       By default no merge_bvec_fn is defined for a queue, and only the fixed limits are honored.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						   BLK_QUEUE_MERGE_BVEC(9)