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Commit 32960613 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: correctly handle non ->{read,write}_iter() file_operations 



Currently we just -EINVAL a read or write to an fd that isn't backed
by ->read_iter() or ->write_iter(). But we can handle them just fine,
as long as we punt fo async context first.

Implement a simple loop function for doing ->read() or ->write()
instead, and ensure we call it appropriately.

Reported-by: default avatar李通洲 <carter.li@eoitek.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5262f567

fs/io_uring.c

+54 −6
Original line number Diff line number Diff line
@@ -1298,6 +1298,51 @@ static void io_async_list_note(int rw, struct io_kiocb *req, size_t len) 
	}

}



/*

 * For files that don't have ->read_iter() and ->write_iter(), handle them

 * by looping over ->read() or ->write() manually.

 */

static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,

			   struct iov_iter *iter)

{

	ssize_t ret = 0;



	/*

	 * Don't support polled IO through this interface, and we can't

	 * support non-blocking either. For the latter, this just causes

	 * the kiocb to be handled from an async context.

	 */

	if (kiocb->ki_flags & IOCB_HIPRI)

		return -EOPNOTSUPP;

	if (kiocb->ki_flags & IOCB_NOWAIT)

		return -EAGAIN;



	while (iov_iter_count(iter)) {

		struct iovec iovec = iov_iter_iovec(iter);

		ssize_t nr;



		if (rw == READ) {

			nr = file->f_op->read(file, iovec.iov_base,

					      iovec.iov_len, &kiocb->ki_pos);

		} else {

			nr = file->f_op->write(file, iovec.iov_base,

					       iovec.iov_len, &kiocb->ki_pos);

		}



		if (nr < 0) {

			if (!ret)

				ret = nr;

			break;

		}

		ret += nr;

		if (nr != iovec.iov_len)

			break;

		iov_iter_advance(iter, nr);

	}



	return ret;

}



static int io_read(struct io_kiocb *req, const struct sqe_submit *s,

		   bool force_nonblock)

{
@@ -1315,8 +1360,6 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s, 


	if (unlikely(!(file->f_mode & FMODE_READ)))

		return -EBADF;

	if (unlikely(!file->f_op->read_iter))

		return -EINVAL;



	ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);

	if (ret < 0)
@@ -1331,7 +1374,11 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s, 
	if (!ret) {

		ssize_t ret2;



		if (file->f_op->read_iter)

			ret2 = call_read_iter(file, kiocb, &iter);

		else

			ret2 = loop_rw_iter(READ, file, kiocb, &iter);



		/*

		 * In case of a short read, punt to async. This can happen

		 * if we have data partially cached. Alternatively we can
@@ -1376,8 +1423,6 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s, 
	file = kiocb->ki_filp;

	if (unlikely(!(file->f_mode & FMODE_WRITE)))

		return -EBADF;

	if (unlikely(!file->f_op->write_iter))

		return -EINVAL;



	ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);

	if (ret < 0)
@@ -1415,7 +1460,10 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s, 
		}

		kiocb->ki_flags |= IOCB_WRITE;



		if (file->f_op->write_iter)

			ret2 = call_write_iter(file, kiocb, &iter);

		else

			ret2 = loop_rw_iter(WRITE, file, kiocb, &iter);

		if (!force_nonblock || ret2 != -EAGAIN) {

			io_rw_done(kiocb, ret2);

		} else {