BLK_QUEUE_START_TAG(9) Block Devices BLK_QUEUE_START_TAG(9)
NAME blk_queue_start_tag - find a free tag and assign it
SYNOPSIS int blk_queue_start_tag(struct request_queue * q, struct request * rq);
ARGUMENTS q the request queue for the device
rq the block request that needs tagging
DESCRIPTION This can either be used as a stand-alone helper, or possibly be assigned as the queue prep_rq_fn (in which case struct request automagically gets a tag assigned). Note that this function assumes that any type of request can be queued! if this is not true for your device, you must check the request type before calling this function. The request will also be removed from the request queue, so it´s the drivers responsibility to readd it if it should need to be restarted for some reason.
NOTES queue lock must be held.
COPYRIGHT Kernel Hackers Manual 2.6. November 2013 BLK_QUEUE_START_TAG(9)