whiteout test

gistfile1.txt

root@host:~/ovl# ls
root@host:~/ovl# mkdir layerA layerB layerC work mnt
root@host:~/ovl# touch layerA/a layerB/b layerC/c
root@host:~/ovl# mount ovl -t overlay -o lowerdir=layerA,upperdir=layerB,workdir=work mnt
root@host:~/ovl# ls -la mnt
total 8
drwxr-xr-x 1 root root 4096 Jun 16 17:32 .
drwxr-xr-x 7 root root 4096 Jun 16 17:32 ..
-rw-r--r-- 1 root root    0 Jun 16 17:32 a
-rw-r--r-- 1 root root    0 Jun 16 17:32 b
root@host:~/ovl# rm mnt/a
root@host:~/ovl# umount mnt
root@host:~/ovl# ls -la layerB/
total 8
drwxr-xr-x 2 root root 4096 Jun 16 17:32 .
drwxr-xr-x 7 root root 4096 Jun 16 17:32 ..
c--------- 2 root root 0, 0 Jun 16 17:32 a
-rw-r--r-- 1 root root    0 Jun 16 17:32 b
root@host:~/ovl# mount ovl -t overlay -o lowerdir=layerB:layerC mnt
root@host:~/ovl# ls -la mnt
total 8
drwxr-xr-x 1 root root 4096 Jun 16 17:32 .
drwxr-xr-x 7 root root 4096 Jun 16 17:32 ..
-rw-r--r-- 1 root root    0 Jun 16 17:32 b
-rw-r--r-- 1 root root    0 Jun 16 17:32 c
root@host:~/ovl# umount mnt
root@host:~/ovl# mount ovl -t overlay -o lowerdir=layerC:layerB mnt
root@host:~/ovl# ls -la mnt
total 8
drwxr-xr-x 1 root root 4096 Jun 16 17:32 .
drwxr-xr-x 7 root root 4096 Jun 16 17:32 ..
-rw-r--r-- 1 root root    0 Jun 16 17:32 b
-rw-r--r-- 1 root root    0 Jun 16 17:32 c