req->error only used for iopoll

mainline inclusion
from mainline-5.2-rc1
commit 5dcf877f
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27
CVE: NA
---------------------------

No need to set it in io_poll_add; io_poll_complete doesn't use it to set
the result in the CQE.
Signed-off-by: NStefan Bühler <source@stbuehler.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NZhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Nyangerkun <yangerkun@huawei.com>
Reviewed-by: Nzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>

fs/io_uring.c

@@ -333,7 +333,7 @@ struct io_kiocb {
 #define REQ_F_IO_DRAIN		32	/* drain existing IO first */
 #define REQ_F_IO_DRAINED	64	/* drain done */
 	u64			user_data;
-	u32			error;
+	u32			error;	/* iopoll result from callback */
 	u32			sequence;
 
 	struct work_struct	work;
@@ -1517,7 +1517,6 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		spin_unlock(&poll->head->lock);
 	}
 	if (mask) { /* no async, we'd stolen it */
-		req->error = mangle_poll(mask);
 		ipt.error = 0;
 		io_poll_complete(ctx, req, mask);
 	}