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@xxxxxxxxx>
---
fs/iomap.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
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);
--
2.17.1
