Re: [PATCH] ext4: enable acls and user_xattr by default

[Ted Ts'o <tytso@mit.edu>]

On Thu, Feb 24, 2011 at 02:57:40PM +0100, Jan Kara wrote:
>   I've actually tried that before posting my email and it's not like that.
> I did:
> jack@quack:~/source> echo 'aaa' >/tmp/f
> jack@quack:~/source> chmod 600 /tmp/f
> jack@quack:~/source> setfacl -m u:nobody:rw /tmp/f
> jack@quack:~/source> sudo su nobody -c "cat /tmp/f"
> aaa
> jack@quack:~/source> sudo su news -c "cat /tmp/f"
> cat: /tmp/f: Permission denied

Hmm... yes, but it's a bit more complicated.  Look at this, and note
how remounting the file system without acl's gave the group "users" rw
access to the file /mnt/f.

						- Ted

<tytso.root@tytso-glaptop> {/}  
2100# mount -o acl /dev/funarg/test /mnt
<tytso.root@tytso-glaptop> {/}  
2101# echo aaa > /mnt/f
<tytso.root@tytso-glaptop> {/}  
2102# chown root:users /mnt/f
<tytso.root@tytso-glaptop> {/}  
2103# chmod 400 /mnt/f
<tytso.root@tytso-glaptop> {/}  
2104# ls -l /mnt/f
4 -r-------- 1 root users 4 Feb 24 11:46 /mnt/f
<tytso.root@tytso-glaptop> {/}  
2105# setfacl -m u:tytso:rw /mnt/f
<tytso.root@tytso-glaptop> {/}  
2106# getfacl /mnt/f
getfacl: Removing leading '/' from absolute path names
# file: mnt/f
# owner: root
# group: users
user::r--
user:tytso:rw-
group::---
mask::rw-
other::---

<tytso.root@tytso-glaptop> {/}  
2107# ls -l /mnt/f
8 -r--rw----+ 1 root users 4 Feb 24 11:46 /mnt/f
<tytso.root@tytso-glaptop> {/}  
2108# umount /mnt
<tytso.root@tytso-glaptop> {/}  
2109# mount -o noacl /dev/funarg/test /mnt
<tytso.root@tytso-glaptop> {/}  
2110# ls -l /mnt/f
8 -r--rw---- 1 root users 4 Feb 24 11:46 /mnt/f