geom/sched/subr_disk.c

36  * current head position (bioq->last_offset) in the scan direction, i.e.
47  *   bioq_first()	return the head of the queue, without removing;
49  *   bioq_takefirst()	return and remove the head of the queue,
50  *		updating the 'current head position' as
53  * When updating the 'current head position', we assume that the result of
55  * represents the head position once the request is complete.
63  *	update, but its use tracks the head position in a better way.
64  *	Historical behaviour was also to update the head position when
67  *	has no method to update the head position; secondly, once
69  *	the actual head position, so the final one is our best guess.
81  * bioq_insert_head()	insert an entry at the head, update
87  *		bioq_takefirst() if invoked on the head of the queue.
97  * at the head of the queue even after subsequent bioq_disksort().
106 gs_bioq_init(struct bio_queue_head *head)
109 	TAILQ_INIT(&head->queue);
110 	head->last_offset = 0;
111 	head->insert_point = NULL;
115 gs_bioq_remove(struct bio_queue_head *head, struct bio *bp)
118 	if (head->insert_point == NULL) {
119 		if (bp == TAILQ_FIRST(&head->queue))
120 			head->last_offset = bp->bio_offset + bp->bio_length;
121 	} else if (bp == head->insert_point)
122 		head->insert_point = NULL;
124 	TAILQ_REMOVE(&head->queue, bp, bio_queue);
128 gs_bioq_flush(struct bio_queue_head *head, struct devstat *stp, int error)
132 	while ((bp = gs_bioq_takefirst(head)) != NULL)
137 gs_bioq_insert_head(struct bio_queue_head *head, struct bio *bp)
140 	if (head->insert_point == NULL)
141 		head->last_offset = bp->bio_offset;
142 	TAILQ_INSERT_HEAD(&head->queue, bp, bio_queue);
146 gs_bioq_insert_tail(struct bio_queue_head *head, struct bio *bp)
149 	TAILQ_INSERT_TAIL(&head->queue, bp, bio_queue);
150 	head->insert_point = bp;
151 	head->last_offset = bp->bio_offset;
155 gs_bioq_first(struct bio_queue_head *head)
158 	return (TAILQ_FIRST(&head->queue));
162 gs_bioq_takefirst(struct bio_queue_head *head)
166 	bp = TAILQ_FIRST(&head->queue);
168 		gs_bioq_remove(head, bp);
178 gs_bioq_bio_key(struct bio_queue_head *head, struct bio *bp)
181 	return ((uoff_t)(bp->bio_offset - head->last_offset));
192 gs_bioq_disksort(struct bio_queue_head *head, struct bio *bp)
204 		gs_bioq_insert_tail(head, bp);
209 	key = gs_bioq_bio_key(head, bp);
210 	cur = TAILQ_FIRST(&head->queue);
212 	if (head->insert_point) {
213 		prev = head->insert_point;
214 		cur = TAILQ_NEXT(head->insert_point, bio_queue);
217 	while (cur != NULL && key >= gs_bioq_bio_key(head, cur)) {
223 		TAILQ_INSERT_HEAD(&head->queue, bp, bio_queue);
225 		TAILQ_INSERT_AFTER(&head->queue, prev, bp, bio_queue);