Re: [PATCH] COW and checksumming ioctls

["Joshua J. Berry" <des@condordes.net>]

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On Sunday 22 June 2008 07:10:06 Chris Mason wrote:
> On Sat, 2008-06-21 at 03:27 -0400, Christoph Hellwig wrote:
> > Synthetic xattrs are a really utterly horrible interface.  Xattrs on
> > disk are nice and simple, but the Linux invention of making some up
> > on the fly, starting with the Posix ACL interface makes the
> > implementation not just utterly complicated but also confuses backup
> > programs.
>
> The idea is that backup programs already know how to do xattrs and can
> easily be changed to preserve them.  Every ioctl interface we
> create/make up has to be handed coded into the backup program.
>
> I know xattrs are ugly, but we need to weigh the cost of the perfect
> interface with the availability of a common one.  Dave Chinner had
> talked about using xattrs to control file behavior in XFS as well, not
> sure if that ever happened.

+1 for xattrs.  From a user perspective, they're simpler than futzing around 
with special btrfs programs to set/unset attributes, and as Chris points out, 
having backup programs pick them up is a good thing.

If virtual xattrs are so complicated/messy to implement, perhaps they should 
be made simpler.  I honestly can't think of a better interface for something 
like this.

-- Josh


-- 
Joshua J. Berry

"I haven't lost my mind -- it's backed up on tape somewhere."
    -- /usr/games/fortune


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