fuse: check size of FUSE_NOTIFY_INVAL_ENTRY message

FUSE_NOTIFY_INVAL_ENTRY didn't check the length of the write so the
message processing could overrun and result in a "kernel BUG at
fs/fuse/dev.c:629!"

Reported-by: Han-Wen Nienhuys <hanwenn@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
static void fuse_request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
{
	spin_lock(&fc->lock);
	if (fc->connected) {
		fuse_request_send_nowait_locked(fc, req);
		spin_unlock(&fc->lock);
	} else {
		req->out.h.error = -ENOTCONN;
		request_end(fc, req);
	}
}

static void fuse_request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
{
	spin_lock(&fc->lock);
	if (fc->connected) {
		fuse_request_send_nowait_locked(fc, req);
		spin_unlock(&fc->lock);
	} else {
		req->out.h.error = -ENOTCONN;
		request_end(fc, req);
	}
}
