io_uring: fix truncated async read/readv and write/writev retry

Ensure we keep the truncated value, if we did truncate it. If not, we
might read/write more than the registered buffer size.

Also for retry, ensure that we return the truncated mapped value for
the vectorized versions of the read/write commands.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9f1a462..55afae6 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2360,6 +2360,7 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
                                *iovec = NULL;
                                return PTR_ERR(buf);
                        }
+                       req->rw.len = sqe_len;
                }
 
                ret = import_single_range(rw, buf, sqe_len, *iovec, iter);
@@ -2379,8 +2380,10 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
 
        if (req->flags & REQ_F_BUFFER_SELECT) {
                ret = io_iov_buffer_select(req, *iovec, needs_lock);
-               if (!ret)
-                       iov_iter_init(iter, rw, *iovec, 1, (*iovec)->iov_len);
+               if (!ret) {
+                       ret = (*iovec)->iov_len;
+                       iov_iter_init(iter, rw, *iovec, 1, ret);
+               }
                *iovec = NULL;
                return ret;
        }