Changing one column with specific rule in R

This is my df:

df_1 <- structure(list(col1 = c(0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 3, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 
0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0)), class = c("tbl_df", "tbl", 
"data.frame"), row.names = c(NA, -45L))

I want to create another column where values follow this order:

above row with value 2 will have value 1. Rows between 2 and 3 will have value 2, Rows between 3 and 4 will have value 3, Rows between 4 and 5 will have value 4, Rows between 5 and 6 will have value 5, Rows bellow 6 will have value 6.

In the end my col1 wil be:

col1 = c(1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 
3, 3, 3, 3, 3,3, 3, 3, 3, 4, 4,4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 
5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6)

How can I do this? Is it possible do it with tidyverse packages?

df_1 %>%
  mutate(col1 = cummax(replace(col1, col1 == 0, 1)))

  col1
1     1
2     1
3     1
4     1
5     2
6     2
7     2
8     2
9     2
10    2
11    2
12    3
13    3
14    3
15    3
16    3
17    3
18    3
19    3
20    3
21    3
22    3
23    4
24    4
25    4
26    4
27    4
28    4
29    4
30    4
31    4
32    4
33    5
34    5
35    5
36    5
37    5
38    5
39    5
40    5
41    5
42    6
43    6
44    6
45    6