[PATCH 5.15 118/136] io_uring: fix issue with io_write() not always undoing sb_start_write()

Greg Kroah-Hartman
2022-08-29T11:20:53Z

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>
---
fs/io_uring.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3720,7 +3720,12 @@ done:
copy_iov:
iov_iter_restore(iter, state);
ret = io_setup_async_rw(req, iovec, inline_vecs, iter, 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() */