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.