Fwd: Btrfs compression

[Matt McCutchen]

On Sat, 2010-05-01 at 05:32 +0200, Kevin Kofler wrote:
> Adam Jackson wrote:
> > find / -xdev -type f | while read i; do
> >     cp $i /tmp/tmp
> >     rm $i
> >     mv /tmp/tmp $i
> > done
> 
> I presume that cp should be cp -p?

"cp --preserve=all" is needed to preserve SELinux context and extended
attributes.

> And I guess it would be better to do a mv 
> -f rather than rm + mv, otherwise you're going to have trouble when you hit 
> /bin/mv. :-) And of course this needs to run as root.
> 
> > Obviously, don't actually run that.
> 
> Well, are there any other caveats than the ones I listed above?

- Filenames with newlines will get mangled.

- Hard links will be broken.

- If a file is changed while the script is working on it, it may be
clobbered with the old contents.  Similarly, if it is moved, it may
reappear in the old location.

The process should really be run using boot media, not on a live root
filesystem.  This avoids the issue of manipulating the /bin/mv being
used.

Here's the approach I would use, starting in the filesystem root:

mkdir TEMP
(GLOBIGNORE=TEMP; mv * TEMP)
rsync -aAXH --remove-source-files TEMP/ .
rm -rf TEMP

-- 
Matt