[PATCH] afs: Fix afs_listxattr() to not list afs ACL special xattrs

[Gaja Sophie Peters]

Am 09.03.21 um 22:42 schrieb David Howells:
> Gaja Sophie Peters <gaja.peters at math.uni-hamburg.de> wrote:
> 
>>> Fix afs_listxattr() so that it doesn't list any of the AFS ACL xattrs.  It
>>> does mean, however, that getfattr won't list them, though they can still be
>>> accessed with getxattr() and setxattr().
>> This seems by far the cleanest and most simple solution. I tested it now
>> and it works for me in all four (six) cases correctly with getxattr and
>> listxattr.
> 
> Can I put that down as a Tested-by?

Yes, I guess so - it wasn't a particularly formal or scripted test, but
everything worked now that wasn't working for me before, and I couldn't
think of anything to not make it work.

The "test-environment" was Kernel 5.11.3 (from kernel.org) with patches
from both
http://lists.infradead.org/pipermail/linux-afs/2021-March/003501.html
http://lists.infradead.org/pipermail/linux-afs/2021-March/003524.html

(no other patches)


[Offtopic]

>> P.S. I found possibly also why adding the line "afs.*  skip" to the file
>> "/etc/xattr.conf" didn't change anything a few days ago: when looking
>> with strace at the above cp command, it looks for "/usr/etc/xattr.conf",
>> but that file doesn't exist of course. Once I copy /etc/xattr.conf to
>> /usr/etc/xattr.conf, cp --preseve=xattr doesn't give any error-messages
>> any more. Bug in cp? or in some library? anyways, it's not kafs.
> 
> You're using Ubuntu, right?  It may put the file in a different place.  Fedora
> has:
> 
> 	[root at andromeda ~]# rpm -ql libattr
> 	/etc/xattr.conf
> 	...

Same in Ubuntu (20.04).

$ dpkg -L libattr1
/etc/xattr.conf
...

It's not the xattr.conf that's in the wrong place, it was cp *looking*
for it in the wrong place. (which isn't a bug in cp/coreutils, but in
libattr, or the way Ubuntu makes the packages from it)
Some random "greps" in the Ubuntu-source-code for "attr":

	debian/rules:	  --prefix=/usr \
	debian/libattr1.install:usr/etc/xattr.conf etc
	configure:ac_default_prefix=/usr
	sysconfdir='${prefix}/etc'
	-DSYSCONFDIR=\"$(sysconfdir)\"
	#define ATTR_CONF SYSCONFDIR "/xattr.conf"

All that combined means the file is placed in /etc/xattr.conf, but the
rest of the source-code expects it in /usr/etc/xattr.conf


> Also what version of libattr do you have installed?  I have 2.4.48.
	2.4.48-5

> That said, the change that you can see here:
> 
> 	https://git.savannah.nongnu.org/cgit/attr.git/log/
> 
> with subject "xattr.conf: Indicate afs metadata xattrs should be skipped when
> copying" hasn't been released yet.  I'll ask Andreas about that.

I know, I added the line manually.

Greetings,
Gaja

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