Re: xattr namespace question

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

On Wed, 2006-03-22 at 10:58 +1100, Nathan Scott wrote:
> On Tue, Mar 21, 2006 at 05:21:19AM -0700, Andreas Dilger wrote:
> > On Mar 21, 2006  12:06 +0000, Steven Whitehouse wrote:
> > > In order to remove the final ioctl() call in the GFS2 filesystem its
> > > been suggested that we use xattrs as a replacement interface. Mostly
> > > this is self-explanatory however there is one question that I've not
> > > been able to resolve 100% satisfactorily, which is what the namespace
> > > should look like.
> > > 
> > > We have a bunch of boolean flags, so (using the example of the journaled
> > > data flag) should our xattrs be called something along the lines of
> 
> "boolean flags" sounds alot more like the lsattr/chattr inode flags
> as Andreas points out.  There is already a data journalling (j) flag
> there too.
> 
Yes, and for flags which are supported by ext2/3 this seems a sensible
route to take and I've already made a start to supporting that ioctl().
However there are still some other flags which don't fit in with the
existing ext2 flags, so for those we'll have to look for a different
method for those.

> > > system.gfs2.jdata (this seems to be most popular suggestion amoung those
> > > I've asked privately), or perhaps system.fs.gfs2.jdata or indeed is the
> > > system namespace reserved for something special so that we should use a
> > > special gfs2 namespace instead?
> 
> The choice typically depends on what the permissions model for
> access to the attribute needs to be.  See attr(5).
> 
Well from that it would appear that system is the right namespace to
choose. So the current plan is to make all the flags available via
xattrs and those compatible with ext2, via the ext2 compatible ioctl()
interface as well.

Thanks for the pointing me in the right direction,

Steve.