* For an empty barrier, there's no actual BAR request, which
* in turn makes POSTFLUSH unnecessary. Mask them off.
*/
- if (!rq->hard_nr_sectors)
+ if (!rq->hard_nr_sectors) {
q->ordered &= ~(QUEUE_ORDERED_DO_BAR |
QUEUE_ORDERED_DO_POSTFLUSH);
+ /*
+ * Empty barrier on a write-through device w/ ordered
+ * tag has no command to issue and without any command
+ * to issue, ordering by tag can't be used. Drain
+ * instead.
+ */
+ if ((q->ordered & QUEUE_ORDERED_BY_TAG) &&
+ !(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) {
+ q->ordered &= ~QUEUE_ORDERED_BY_TAG;
+ q->ordered |= QUEUE_ORDERED_BY_DRAIN;
+ }
+ }
/* stash away the original request */
elv_dequeue_request(q, rq);
* Description:
* Issue a flush for the block device in question. Caller can supply
* room for storing the error offset in case of a flush error, if they
- * wish to. Caller must run wait_for_completion() on its own.
+ * wish to.
*/
int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
{