From: Pavel Begunkov asml.silence@gmail.com
We can't re-import or modify iterators from iocb callbacks, it's not safe as it might be reverted and/or reexpanded while unwinding stack. It's also not safe to resubmit as io-wq thread will race with stack undwinding for the iterator and other data.
Disallow resubmission from callbacks, it can fail some cases that were handled before, but the possibility of such a failure was a part of the API from the beginning and so it should be fine.
Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/io_uring.c | 39 --------------------------------------- 1 file changed, 39 deletions(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2579,45 +2579,6 @@ static void io_complete_rw_common(struct #ifdef CONFIG_BLOCK static bool io_resubmit_prep(struct io_kiocb *req, int error) { - struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; - ssize_t ret = -ECANCELED; - struct iov_iter iter; - int rw; - - if (error) { - ret = error; - goto end_req; - } - - switch (req->opcode) { - case IORING_OP_READV: - case IORING_OP_READ_FIXED: - case IORING_OP_READ: - rw = READ; - break; - case IORING_OP_WRITEV: - case IORING_OP_WRITE_FIXED: - case IORING_OP_WRITE: - rw = WRITE; - break; - default: - printk_once(KERN_WARNING "io_uring: bad opcode in resubmit %d\n", - req->opcode); - goto end_req; - } - - if (!req->async_data) { - ret = io_import_iovec(rw, req, &iovec, &iter, false); - if (ret < 0) - goto end_req; - ret = io_setup_async_rw(req, iovec, inline_vecs, &iter, false); - if (!ret) - return true; - kfree(iovec); - } else { - return true; - } -end_req: req_set_fail_links(req); return false; }