[PATCH 5.19 133/158] io_uring: fix issue with io_write() not always undoing sb_start_write()

Greg Kroah-Hartman
2022-08-29T11:32:53Z

From: Jens Axboe <axboe@kernel.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@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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() */