linux-kernel - [PATCH 5.19 133/158] io_uring: fix issue with io_write() not always undoing sb_start

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Date:   Mon, 29 Aug 2022 12:59:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.19 133/158] io_uring: fix issue with io_write() not always undoing sb_start_write()

From: Jens Axboe <axboe@...nel.dk>

commit e053aaf4da56cbf0afb33a0fda4a62188e2c0637 upstream.

This is actually an older issue, but we never used to hit the -EAGAIN
path before having done sb_start_write(). Make sure that we always call
kiocb_end_write() if we need to retry the write, so that we keep the
calls to sb_start_write() etc balanced.

Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 io_uring/io_uring.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -4331,7 +4331,12 @@ done:
 copy_iov:
 		iov_iter_restore(&s->iter, &s->iter_state);
 		ret = io_setup_async_rw(req, iovec, s, false);
-		return ret ?: -EAGAIN;
+		if (!ret) {
+			if (kiocb->ki_flags & IOCB_WRITE)
+				kiocb_end_write(req);
+			return -EAGAIN;
+		}
+		return ret;
 	}
 out_free:
 	/* it's reportedly faster than delegating the null check to kfree() */