[PATCH] Only the first two bits in bio->bi_rw and rq->flags match
Not three, as assumed. This causes the barrier bit to be needlessly set
for some IO.
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index ab17c72..61d6b3c 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3491,8 +3491,8 @@
void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
{
- /* first three bits are identical in rq->flags and bio->bi_rw */
- rq->flags |= (bio->bi_rw & 7);
+ /* first two bits are identical in rq->flags and bio->bi_rw */
+ rq->flags |= (bio->bi_rw & 3);
rq->nr_phys_segments = bio_phys_segments(q, bio);
rq->nr_hw_segments = bio_hw_segments(q, bio);
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index 2346a1d..7520cc1 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -148,7 +148,7 @@
u32 what)
{
struct blk_trace *bt = q->blk_trace;
- int rw = rq->flags & 0x07;
+ int rw = rq->flags & 0x03;
if (likely(!bt))
return;