patch draft for extended attributes on linux

[jw schultz]

On Wed, Jun 25, 2003 at 10:34:38AM +1000, Martin Pool wrote:
> This draft patch adds support for transferring extended attributes
> with a new --xattr option.  It ought to work on Linux with XFS or
> ext2/ext3 filesystems with the SGI/bestbits attribute system.
> 
> It is partially working, but there seems to be some kind of hang bug
> while transferring the file list.  I suspect it might be provoking a
> problem in io.c.
> 
> You need to rerun autoconf, autoheader and configure after applying
> it.
> 
> There is no mtime for xattrs, so they are transferred every time as
> part of the file list.  This means that they will be updated correctly
> if you change attributes but do not change the file.

That lack of an mtime for xattr could well cause
difficulties for backup systems as well.  Perhaps a note to
the filesystems people is in order.  The problem is that you
can't use mtime for these.  It really needs its own
timestamp, perhaps as a mandatory system attribute.

I don't much care for
sending the xattrs as part of the file list.  Even the 4KB
ext[23] _currently_ limit it to is huge.

> I wrote this because it was required by a colleague.  I have mixed
> feelings about whether this ought to be merged, even once it's working
> correctly.  rsync hardly needs more options or protocol
> variations. :-( (Amusingly enough I once said "-xattr" instead of
> "--xattr" and it silently did something else.)

I don't have a problem with the idea of adding such an
option and protocol variant to rsync.  Doing it this way i
do have more than mixed feelings about merger.  My feelings
on this are already well articulated in the archives.
Nevertheless i do think it worth having something in
patches.  I have a vague recollection of an earlier patch
that did an lsattr and synced that before applying it,
perhaps something in that vein might be more apropos.