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Re: Tutorial to ACLs and XFS handling

To: Florian.Lindner@xxxxxx
Subject: Re: Tutorial to ACLs and XFS handling
From: Tim Shimmin <tes@xxxxxxx>
Date: Fri, 7 Jun 2002 15:10:49 +1000
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <1023380095.5878.23.camel@xxxxxxxxxxxxxxxxxxxxxx>; from sandeen@xxxxxxx on Thu, Jun 06, 2002 at 11:14:55AM -0500
References: <000d01c20d57$6f7b1b90$0200a8c0@florian> <1023380095.5878.23.camel@xxxxxxxxxxxxxxxxxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
Hi Florian,

As Eric mentioned, the acl.bestbits.at site is the one to go to.
The userland tools and libraries mentioned on this site are 
compatible with the xfs kernel (and stored in our tree).
Andreas Gruenbacher is the maintainer of these and questions
about them should be sent to his mailing list.

Some XFS specific things which come to mind:
  - xfs stores ACLs in XFS extended attributes
  - xfsdump and xfsrestore dumps and restores
    extended attributes, thus it dumps and restores ACLs
  - XFS ACLs are limited to 25 ACL entries (ACEs)
    - which leaves 25-4=21 ACEs for user and group ACEs
    - the guys at Snapserver (jtrostel et al) have
      some patches for extended permissions and larger
      ace count (though nathans@xxxxxxx had suggestions
      for a nicer implementation I believe)
  - if ACLs are small enough (<=20 ACEs (20*12+4=244<256))
    and the inode is large enough (mkfs.xfs -i size=), 
    then the ACLs may be stored in the inode which can speed up access
  

--Tim

On Thu, Jun 06, 2002 at 11:14:55AM -0500, Eric Sandeen wrote:
> Florian - 
> 
> Have you looked at http://acl.bestbits.at/?  Not xfs-specific, but:
> 
> What are extended attributes?
> What are access control lists?
> Using extended attributes and access control lists
> Frequently asked questions 
> 
> etc.
> 
> -Eric
> 
> On Thu, 2002-06-06 at 07:41, Florian Lindner wrote:
> > Hello,
> > I'm looking for tutorial for ACLs generell und especially how XFS handles
> > them. I'm not interessted in how the implementiation is done, but I want to
> > know from a users point of view. (tool for managing ACLs, ....).
> > Language English or German.
> > Thx,
> > Florian
> 
> 


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