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/block/blk-merge.c b/block/blk-merge.c
index b5c5c4a..73b2356 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -55,7 +55,7 @@
if (!rq->bio)
return;
- cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
+ cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
hw_seg_size = seg_size = 0;
phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
rq_for_each_segment(bv, rq, iter) {
@@ -128,7 +128,7 @@
static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
struct bio *nxt)
{
- if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
+ if (!test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags))
return 0;
if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
@@ -175,7 +175,7 @@
int nsegs, cluster;
nsegs = 0;
- cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
+ cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
/*
* for each bio in rq