Commit 7335e3bf authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: don't forget to adjust io_size 



We have invariant in io_read() of how much we're trying to read spilled
into an iter and io_size variable. The last one controls decision making
about whether to do read-retries. However, io_size is modified only
after the first read attempt, so if we happen to go for a third retry in
a single call to io_read(), we will get io_size greater than in the
iterator, so may lead to various side effects up to live-locking.

Modify io_size each time.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 6bf985dc

fs/io_uring.c

+5 −9
Original line number Diff line number Diff line
@@ -3548,16 +3548,11 @@ static int io_read(struct io_kiocb *req, bool force_nonblock, 
		/* some cases will consume bytes even on error returns */

		iov_iter_revert(iter, io_size - iov_iter_count(iter));

		ret = 0;

	} else if (ret <= 0 || ret == io_size) {

		/* make sure -ERESTARTSYS -> -EINTR is done */

	} else if (ret <= 0 || ret == io_size || !force_nonblock ||

		   (req->file->f_flags & O_NONBLOCK) ||

		   !(req->flags & REQ_F_ISREG)) {

		/* read all, failed, already did sync or don't want to retry */

		goto done;

	} else {

		/* we did blocking attempt. no retry. */

		if (!force_nonblock || (req->file->f_flags & O_NONBLOCK) ||

		    !(req->flags & REQ_F_ISREG))

			goto done;



		io_size -= ret;

	}



	ret2 = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
@@ -3570,6 +3565,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock, 
	/* now use our persistent iterator, if we aren't already */

	iter = &rw->iter;

retry:

	io_size -= ret;

	rw->bytes_done += ret;

	/* if we can retry, do so with the callbacks armed */

	if (!io_rw_should_retry(req)) {