This is a note to let you know that I've just added the patch titled block: don't ignore REQ_NOWAIT for direct IO to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: block-don-t-ignore-req_nowait-for-direct-io.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit b96156bc7d5bddd7831bc3ce763df20abc3070b3 Author: Pavel Begunkov <asml.silence@xxxxxxxxx> Date: Fri Nov 20 17:10:28 2020 +0000 block: don't ignore REQ_NOWAIT for direct IO [ 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@xxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/block_dev.c b/fs/block_dev.c index 79272cdbe827..bd93563477a4 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -246,6 +246,8 @@ __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); @@ -399,6 +401,8 @@ __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;