[lug] du vs df

[Zan Lynx]

On 03/11/2013 04:46 PM, Michael J. Hammel wrote:
> And then, when the file went away, that
> space cleared out, in increments, very fast (but not immediately, as you
> might suspect with clearing an inode).
That is the background deletion happening, as I mentioned that EXT4 
does. I guess EXT3 does it too.

There is a lot of work to be done in various places to update the 
tracking information. I think EXT2/3/4 uses block maps, indirect block 
maps, double indirect block maps and possibly triple indirect block 
maps. Each of these need to be marked clear all the way down the 
structure during a delete.