my_chattr: test file systems mounted on loopback fail with "chattr: Operation not supported while reading flags"

[dfhawthorne]

make run_test_chattr
sudo ./setup_test_chattr.sh 
[sudo] password for douglas: 
sudo ./run_test_chattr.sh
+a
./my_chattr +a ./test_chattr/bfs_mine/target
./my_chattr +a ./test_chattr/msdos_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/msdos_base/target
./my_chattr +a ./test_chattr/ext2_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/minix_base/target
./my_chattr +a ./test_chattr/ext3_mine/target
./my_chattr +a ./test_chattr/ext4_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/bfs_base/target
./my_chattr +a ./test_chattr/minix_mine/target
-a
./my_chattr -a ./test_chattr/bfs_mine/target
./my_chattr -a ./test_chattr/msdos_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/msdos_base/target
./my_chattr -a ./test_chattr/ext2_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/minix_base/target
./my_chattr -a ./test_chattr/ext3_mine/target
./my_chattr -a ./test_chattr/ext4_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/bfs_base/target
./my_chattr -a ./test_chattr/minix_mine/target
=a
./my_chattr =a ./test_chattr/bfs_mine/target
./my_chattr =a ./test_chattr/msdos_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/msdos_base/target
./my_chattr =a ./test_chattr/ext2_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/minix_base/target
./my_chattr =a ./test_chattr/ext3_mine/target
./my_chattr =a ./test_chattr/ext4_mine/target
chattr: Operation not supported while reading flags on ./test_chattr/bfs_base/target
./my_chattr =a ./test_chattr/minix_mine/target

[dfhawthorne]

Commit 172a4fc resolved this issue:

[root@ol8-chattr ~]# df -T /mount/test_fs/ext4_base/target
Filesystem     Type 1K-blocks  Used Available Use% Mounted on
/dev/sdc2      ext4     14679   267     13277   2% /mount/test_fs/ext4_base
[root@ol8-chattr ~]# lsattr /mount/test_fs/ext4_base/target
--------------e---- /mount/test_fs/ext4_base/target
[root@ol8-chattr ~]# chattr +a /mount/test_fs/ext4_base/target
[root@ol8-chattr ~]# lsattr /mount/test_fs/ext4_base/target
-----a--------e---- /mount/test_fs/ext4_base/target

Cannot use loopback filesystems for lsattr and chattr.