[PATCH AUTOSEL 5.10 22/22] block: don't ignore REQ_NOWAIT for direct IO

Sasha Levin
2021-04-05T16:06:24Z

From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit f8b78caf21d5bc3fcfc40c18898f9d52ed1451a5 ]

If IOCB_NOWAIT is set on submission, then that needs to get propagated to
REQ_NOWAIT on the block side. Otherwise we completely lose this
information, and any issuer of IOCB_NOWAIT IO will potentially end up
blocking on eg request allocation on the storage side.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/block_dev.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index fe201b757baa..1b6a34fd1fef 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -280,6 +280,8 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
bio.bi_opf = dio_bio_write_op(iocb);
task_io_account_write(ret);
}
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ bio.bi_opf |= REQ_NOWAIT;
if (iocb->ki_flags & IOCB_HIPRI)
bio_set_polled(&bio, iocb);

@@ -433,6 +435,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
bio->bi_opf = dio_bio_write_op(iocb);
task_io_account_write(bio->bi_iter.bi_size);
}
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ bio->bi_opf |= REQ_NOWAIT;

dio->size += bio->bi_iter.bi_size;
pos += bio->bi_iter.bi_size;
--
2.30.2