[PATCH 2/4] io_uring: fix rw req completion

[Pavel Begunkov <asml.silence@gmail.com>]

WARNING: at fs/io_uring.c:8578 io_ring_exit_work.cold+0x0/0x18

As reissuing is now passed back by REQ_F_REISSUE, kiocb_done() may just
set the flag and do nothing leaving dangling requests. The handling is a
bit fragile, e.g. can't just complete them because the case of reading
beyond file boundary needs blocking context to return 0, otherwise it
may be -EAGAIN.

Go the easy way for now, just emulate how it was by io_rw_reissue() in
kiocb_done()

Fixes: 230d50d448ac ("io_uring: move reissue into regular IO path")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f1881ac0744b..de5822350345 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2762,6 +2762,7 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
 {
 	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
 	struct io_async_rw *io = req->async_data;
+	bool check_reissue = (kiocb->ki_complete == io_complete_rw);
 
 	/* add previously done IO, if any */
 	if (io && io->bytes_done > 0) {
@@ -2777,6 +2778,11 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
 		__io_complete_rw(req, ret, 0, issue_flags);
 	else
 		io_rw_done(kiocb, ret);
+
+	if (check_reissue && req->flags & REQ_F_REISSUE) {
+		req->flags &= ~REQ_F_REISSUE;
+		io_rw_reissue(req);
+	}
 }
 
 static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter)
-- 
2.24.0