block: make queue flags non-atomic
We can save some atomic ops in the IO path, if we clearly define
the rules of how to modify the queue flags.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 51be533..73326e7 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -873,10 +873,13 @@
q->max_hw_sectors = t->limits.max_hw_sectors;
q->seg_boundary_mask = t->limits.seg_boundary_mask;
q->bounce_pfn = t->limits.bounce_pfn;
+ /* XXX: the below will probably go bug. must ensure there can be no
+ * concurrency on queue_flags, and use the unlocked versions...
+ */
if (t->limits.no_cluster)
- q->queue_flags &= ~(1 << QUEUE_FLAG_CLUSTER);
+ queue_flag_clear(QUEUE_FLAG_CLUSTER, q);
else
- q->queue_flags |= (1 << QUEUE_FLAG_CLUSTER);
+ queue_flag_set(QUEUE_FLAG_CLUSTER, q);
}
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 87620b7..acd716b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -282,7 +282,8 @@
kfree(new);
return NULL;
}
- set_bit(QUEUE_FLAG_CLUSTER, &new->queue->queue_flags);
+ /* Can be unlocked because the queue is new: no concurrency */
+ queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, new->queue);
blk_queue_make_request(new->queue, md_fail_request);