[PATCH 2/8] block: wire up block device ->iopoll()

[Jens Axboe <axboe@xxxxxxxxx>]

Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
 fs/block_dev.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index d233a59ea364..711cd5a3469e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -273,6 +273,7 @@ struct blkdev_dio {
 	};
 	size_t			size;
 	atomic_t		ref;
+	blk_qc_t		qc;
 	bool			multi_bio : 1;
 	bool			should_dirty : 1;
 	bool			is_sync : 1;
@@ -281,6 +282,21 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct blkdev_dio *dio = READ_ONCE(kiocb->private);
+
+	/* dio can be NULL here, if the IO hasn't been submitted yet */
+	if (dio) {
+		struct block_device *bdev;
+
+		bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+		return blk_poll(bdev_get_queue(bdev), READ_ONCE(dio->qc), wait);
+	}
+
+	return 0;
+}
+
 static void blkdev_bio_end_io(struct bio *bio)
 {
 	struct blkdev_dio *dio = bio->bi_private;
@@ -335,7 +351,6 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 	bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
 	bool is_read = (iov_iter_rw(iter) == READ), is_sync;
 	loff_t pos = iocb->ki_pos;
-	blk_qc_t qc = BLK_QC_T_NONE;
 	int ret = 0;
 
 	if ((pos | iov_iter_alignment(iter)) &
@@ -355,6 +370,9 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 	dio->size = 0;
 	dio->multi_bio = false;
 	dio->should_dirty = is_read && iter_is_iovec(iter);
+	dio->qc = BLK_QC_T_NONE;
+
+	WRITE_ONCE(iocb->private, dio);
 
 	/*
 	 * Don't plug for HIPRI/polled IO, as those should go straight
@@ -395,7 +413,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 			if (iocb->ki_flags & IOCB_HIPRI)
 				bio->bi_opf |= REQ_HIPRI;
 
-			qc = submit_bio(bio);
+			dio->qc = submit_bio(bio);
 			break;
 		}
 
@@ -423,7 +441,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 			break;
 
 		if (!(iocb->ki_flags & IOCB_HIPRI) ||
-		    !blk_poll(bdev_get_queue(bdev), qc, true))
+		    !blk_poll(bdev_get_queue(bdev), dio->qc, true))
 			io_schedule();
 	}
 	__set_current_state(TASK_RUNNING);
@@ -2061,6 +2079,7 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read_iter	= blkdev_read_iter,
 	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
 	.mmap		= generic_file_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
-- 
2.17.1