Re: NFSv4 ACLs (was: ...ACL's and reiser...)

From: Xuan Baldauf (xuan--reiserfs@baldauf.org)
Date: Thu Jul 27 2000 - 13:43:39 EST


It sounds sophisticated, but you know what is happening if you want to change
access of some crowded directory (like "/usr", or "/home" on some systems)?
Every ACL of every file within this directory gets updated...

Does nobody consider dynamic inheritance? Because when accessing a file, as
access of every path component needs to be checked anyway, dynamic inheritance
should not pose significant overhead, but is a LOT faster for updating, and
probably smarter regarding disk space. The default ACL for a file would be
"inherit all rights from parent", and for files with link count = 1, this ACL
metadata can be left out entirely (because it's the suggested default.)
(Leaving out the ACL metadata, may result in omitting checking for access,
probably making dynamic inheritance faster than static inheritance.)

What do you think?

Xuân. :o)

"Albert D. Cahalan" wrote:

> Michael Gerdts writes:
>
> > When implementing ACL's please read over section 5.9 of the NFSv4 draft.
> > http://www.ietf.org/internet-drafts/draft-ietf-nfsv4-07.txt
> >
> > By designing ACL's (and other things) to work well with NFSv4 from the
> > start, reiserfs will likely have a leg up on the competition inside and
> > outside of the Linux arena for being able to support NFSv4.
>
> Wow, that is almost pure NT 4.0, with 4 of 7 authors being from Sun!
> The only difference is that the 17 access mask bits are all specific;
> there is no concept of mapping generic bits to object-specific bits.
> The inheritance, types, and scanning algorithm are all from NT.
>
> This is a good system; it can handle Coda and Netware fairly well.
>
> Well, there you go. Windows NT features are required for UNIX now.
> Fortunately it isn't too late for Reiserfs and ext2. JFS seems to
> have a few interesting bits already, due to the OS/2 port. XFS will
> need to be dragged out of the dark ages of withdrawn POSIX drafts.
> UFS has several incompatible ACL flavors already, from Sun, Digital...
>
> Windows 2000 added some extra stuff BTW, which is not in NFSv4.

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