Commit 5e929367 authored Mar 18, 2022 by Jens Axboe

io_uring: terminate manual loop iterator loop correctly for non-vecs



The fix for not advancing the iterator if we're using fixed buffers is
broken in that it can hit a condition where we don't terminate the loop.
This results in io-wq looping forever, asking to read (or write) 0 bytes
for every subsequent loop.

Reported-by: Joel Jaeschke <joel.jaeschke@gmail.com>
Link: https://github.com/axboe/liburing/issues/549


Fixes: 16c8d2df ("io_uring: ensure symmetry in handling iter types in loop_rw_iter()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent adf3a9e9

fs/io_uring.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -3612,13 +3612,15 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb req, struct iov_iter iter)
		ret = nr;
		break;
		}
		ret += nr;
		if (!iov_iter_is_bvec(iter)) {
		iov_iter_advance(iter, nr);
		} else {
		req->rw.len -= nr;
		req->rw.addr += nr;
		req->rw.len -= nr;
		if (!req->rw.len)
		break;
		}
		ret += nr;
		if (nr != iovec.iov_len)
		break;
		}