linux-kernel - [PATCH] block: don't ignore REQ

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Date:   Fri, 20 Nov 2020 17:10:28 +0000
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] block: don't ignore REQ_NOWAIT for direct IO

io_uring's direct nowait requests end up waiting on io_schedule() in
sbitmap, that's seems to be so because blkdev_direct_IO() fails to
propagate IOCB_NOWAIT to a bio and hence to blk-mq.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 fs/block_dev.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9e84b1928b94..e7e860c78d93 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -263,6 +263,8 @@ __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);
 
@@ -416,6 +418,8 @@ __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;
-- 
2.24.0