io_uring: fix short read retries for non-reg files

Sockets and other non-regular files may actually expect short reads to
happen, don't retry reads for them. Because non-reg files don't set
FMODE_BUF_RASYNC and so it won't do second/retry do_read, we can filter
out those cases after first do_read() attempt with ret>0.

Cc: stable@vger.kernel.org # 5.9+
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e4c1cdf0325d531c92bc95cf61ab1e73163ad796..862113a9364f8b8f93966ffedc3c8ec227d1a693 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3552,7 +3552,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
 
        /* read it all, or we did blocking attempt. no retry. */
        if (!iov_iter_count(iter) || !force_nonblock ||
-           (req->file->f_flags & O_NONBLOCK))
+           (req->file->f_flags & O_NONBLOCK) || !(req->flags & REQ_F_ISREG))
                goto done;
 
        io_size -= ret;