diff mbox series

[07/27] iomap: ensure that async polled IO is marked REQ_NOWAIT

Message ID 20181130165646.27341-8-axboe@kernel.dk (mailing list archive)
State New, archived
Headers show
Series [01/27] aio: fix failure to put the file pointer | expand

Commit Message

Jens Axboe Nov. 30, 2018, 4:56 p.m. UTC 
We can't wait for polled events to complete, as they may require active
polling from whoever submitted it. If that is the same task that is
submitting new IO, we could deadlock waiting for IO to complete that
this task is supposed to be completing itself.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/iomap.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/iomap.c b/fs/iomap.c
index 16787b3b09fd..96d60b9b2bea 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1451,8 +1451,16 @@  static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
 {
 	atomic_inc(&dio->ref);
 
-	if (dio->iocb->ki_flags & IOCB_HIPRI)
+	if (dio->iocb->ki_flags & IOCB_HIPRI) {
 		bio->bi_opf |= REQ_HIPRI;
+		/*
+		 * For async polled IO, we can't wait for requests to
+		 * complete, as they may also be polled and require active
+		 * reaping.
+		 */
+		if (!dio->wait_for_completion)
+			bio->bi_opf |= REQ_NOWAIT;
+	}
 
 	dio->submit.last_queue = bdev_get_queue(iomap->bdev);
 	dio->submit.cookie = submit_bio(bio);