[Linux-cluster] GFS breaking POSIX exhibited by Samba?

[Lon Hohberger]

On Thu, 2005-09-22 at 10:32 +0200, Axel Thimm wrote:
> Hi,
> 
> I've been stuggling with a strange bug in Samba which required me to
> have some of the tdb files with permissions 0666 to allow Samba to
> work.
> 
> The Samba metadata (locking and connection tables etc) are placed on
> GFS to allow for easier relocation of the Samba services ("poor man's
> clustered samba").
> 
> The problem is that Samba opens some files as root, then drops
> priviledges and finally accesses these files assuming that the root
> access rights are still in order. This does not work under GFS, but
> under any other local fs.
> 
> The Samba developers claim that this is POSIX compliant and that GFS
> is not following POSIX in this matter.
> 
> Is this true? Does POSIX require the fds to not change access
> priviledges even when setuiding to another user?
> 
> If so, why doesn't GFS respect this? A bug or a feature? If the former
> I'll go and bugzilla it. If the latter, can there be a fix for the
> RHEL4 branch?

Definitely file a bugzilla.

It's something that we definitely need to look into.  Off the top of my
head, it sounds like GFS is, indeed, not respecting access rights (and
therefore, POSIX) -- but oddly enough, it may be intentional.  Cluster
semantics don't always line up with POSIX semantics.



-- Lon