blk_queue_headactive(9)
NAME
blk_queue_headactive - indicate whether head of request
queue may be active
SYNOPSIS
void blk_queue_headactive (request_queue_t *q, int active);
ARGUMENTS
q The queue which this applies to.
- active A flag indication where the head of the
- queue is active.
DESCRIPTION
The driver for a block device may choose to leave the cur
rently active request on the request queue, removing it
only when it has completed. The queue handling routines
assume this by default for safety reasons and will not
involve the head of the request queue in any merging or
reordering of requests when the queue is unplugged (and
thus may be working on this particular request).
If a driver removes requests from the queue before pro
cessing them, then it may indicate that it does so, there
by allowing the head of the queue to be involved in merg
ing and reordering. This is done be calling
blk_queue_headactive with an active flag of 0.
If a driver processes several requests at once, it must
remove them (or at least all but one of them) from the
request queue.
- When a queue is plugged the head will be assumed to be
inactive.