From: Pavel Begunkov <asml.silence@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
