attempt_plug_merge —
try to merge with current's plugged list
bool fsfuncattempt_plug_merge ( | struct request_queue * q, |
| struct bio * bio, | |
unsigned int * request_count); |
qrequest_queue new bio is being queued at
bionew bio being queued
request_countout parameter for number of traversed plugged requests
Determine whether bio being queued on q can be merged with a request
on current's plugged list. Returns true if merge was successful,
otherwise false.
This function is called without q->queue_lock; however, elevator is
accessed iff there already are requests on the plugged list which in
turn guarantees validity of the elevator.
Note that, on successful merge, elevator operation
elevator_bio_merged_fn will be called without queue lock. Elevator
must be ready for this.