On Mon, Sep 17, 2012 at 03:58:56AM -0600, Liu Bo wrote:

This comes from one of btrfs's project ideas,
As we defragment files, we break any sharing from other snapshots.
The balancing code will preserve the sharing, and defrag needs to grow this
as well.

Now we're able to fill the blank with this patch, in which we make full use of
backref walking stuff.

Here is the basic idea,
o  set the writeback ranges started by defragment with flag EXTENT_DEFRAG
o  at endio, after we finish updating fs tree, we use backref walking to find
   all parents of the ranges and re-link them with the new COWed file layout by
   adding corresponding backrefs.

Originally patch by Li Zefan [off-list ref]
Signed-off-by: Liu Bo <redacted>

I was trying to fixup the rejects on this patch when I noticed there were no
tabs, only spaces.  Thats not going to work and now I have to go back and make
sure none of your other patches did this.  Thanks,

Josef