[PATCH] io_uring: don't set REQ_F_NOWAIT for regular files opend O_NONBLOCK

[Jiufei Xue <jiufei.xue@linux.alibaba.com>]

When read from a regular file that was opened O_NONBLOCK, it will
return EAGAIN if the page is not cached, which is not expected and
fails the application.

Applications written before expect that the open flag O_NONBLOCK has
no effect on a regular file.

Fix this by not setting REQ_F_NOWAIT for regular files.

Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
---
 fs/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 95df63b..69db8bb 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2107,7 +2107,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
 	/* don't allow async punt if RWF_NOWAIT was requested */
 	if ((kiocb->ki_flags & IOCB_NOWAIT) ||
-	    (req->file->f_flags & O_NONBLOCK))
+	    (!(req->flags & REQ_F_ISREG) && (req->file->f_flags & O_NONBLOCK)))
 		req->flags |= REQ_F_NOWAIT;
 
 	if (force_nonblock)
-- 
1.8.3.1