UPSTREAM: io_uring: fix issue with io_write() not always undoing sb_start_write()

commit e053aaf4 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.

Change-Id: Iea0d91e5b87a5b7db0dee2841563dd03255ce406
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 295219ab)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>