sys/kern/subr_disk.c

84  * current head position (bioq->last_offset) in the scan direction, i.e.
95  *   bioq_first()	return the head of the queue, without removing;
97  *   bioq_takefirst()	return and remove the head of the queue,
98  *		updating the 'current head position' as
101  * When updating the 'current head position', we assume that the result of
103  * represents the head position once the request is complete.
111  *	update, but its use tracks the head position in a better way.
112  *	Historical behaviour was also to update the head position when
115  *	has no method to update the head position; secondly, once
117  *	the actual head position, so the final one is our best guess.
129  * bioq_insert_head()	insert an entry at the head, update
135  *		bioq_takefirst() if invoked on the head of the queue.
145  * at the head of the queue even after subsequent bioq_disksort().
154 bioq_init(struct bio_queue_head *head)
157 	TAILQ_INIT(&head->queue);
158 	head->last_offset = 0;
159 	head->insert_point = NULL;
160 	head->total = 0;
161 	head->batched = 0;
165 bioq_remove(struct bio_queue_head *head, struct bio *bp)
168 	if (head->insert_point == NULL) {
169 		if (bp == TAILQ_FIRST(&head->queue))
170 			head->last_offset = bp->bio_offset + bp->bio_length;
171 	} else if (bp == head->insert_point)
172 		head->insert_point = NULL;
174 	TAILQ_REMOVE(&head->queue, bp, bio_queue);
175 	if (TAILQ_EMPTY(&head->queue))
176 		head->batched = 0;
177 	head->total--;
181 bioq_flush(struct bio_queue_head *head, struct devstat *stp, int error)
185 	while ((bp = bioq_takefirst(head)) != NULL)
190 bioq_insert_head(struct bio_queue_head *head, struct bio *bp)
193 	if (head->insert_point == NULL)
194 		head->last_offset = bp->bio_offset;
195 	TAILQ_INSERT_HEAD(&head->queue, bp, bio_queue);
196 	head->total++;
197 	head->batched = 0;
201 bioq_insert_tail(struct bio_queue_head *head, struct bio *bp)
204 	TAILQ_INSERT_TAIL(&head->queue, bp, bio_queue);
205 	head->total++;
206 	head->batched = 0;
207 	head->insert_point = bp;
208 	head->last_offset = bp->bio_offset;
212 bioq_first(struct bio_queue_head *head)
215 	return (TAILQ_FIRST(&head->queue));
219 bioq_takefirst(struct bio_queue_head *head)
223 	bp = TAILQ_FIRST(&head->queue);
225 		bioq_remove(head, bp);
235 bioq_bio_key(struct bio_queue_head *head, struct bio *bp)
238 	return ((uoff_t)(bp->bio_offset - head->last_offset));
249 bioq_disksort(struct bio_queue_head *head, struct bio *bp)
261 		bioq_insert_tail(head, bp);
272 		bioq_insert_tail(head, bp);
276 	if (bioq_batchsize > 0 && head->batched > bioq_batchsize) {
277 		bioq_insert_tail(head, bp);
282 	key = bioq_bio_key(head, bp);
283 	cur = TAILQ_FIRST(&head->queue);
285 	if (head->insert_point) {
286 		prev = head->insert_point;
287 		cur = TAILQ_NEXT(head->insert_point, bio_queue);
290 	while (cur != NULL && key >= bioq_bio_key(head, cur)) {
296 		TAILQ_INSERT_HEAD(&head->queue, bp, bio_queue);
298 		TAILQ_INSERT_AFTER(&head->queue, prev, bp, bio_queue);
299 	head->total++;
300 	head->batched++;