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)
