From 849a370016a5489c49253338507ee6cc4a08df4b Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 16 Nov 2018 08:37:34 -0700 Subject: block: avoid ordered task state change for polled IO For the core poll helper, the task state setting don't need to imply any atomics, as it's the current task itself that is being modified and we're not going to sleep. For IRQ driven, the wakeup path have the necessary barriers to not need us using the heavy handed version of the task state setting. Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- fs/block_dev.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index 4d79bc80fb41..64ba27b8b754 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -237,9 +237,11 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, qc = submit_bio(&bio); for (;;) { - set_current_state(TASK_UNINTERRUPTIBLE); + __set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(bio.bi_private)) break; + if (!(iocb->ki_flags & IOCB_HIPRI) || !blk_poll(bdev_get_queue(bdev), qc)) io_schedule(); @@ -415,7 +417,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) return -EIOCBQUEUED; for (;;) { - set_current_state(TASK_UNINTERRUPTIBLE); + __set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(dio->waiter)) break; -- cgit v1.2.3-55-g7522