free block bitmap

Alfred Perlstein bright at
Mon Sep 8 16:27:09 PDT 2003

* Eno Thereska <eno at> [030908 15:45] wrote:
> Hi,
> I am using FreeBSD4.4 with FFS as the underlying file system.
> I need to examine which blocks in the file system
> are currently in use. These blocks can be metadata or data blocks.
> I have looked at the FFS code and it seems the only way to get
> the list of free blocks (or busy blocks) is by querying
> each cylinder group's (cg) bitmap of free blocks.
> Is there a global bitmap that keeps track of busy/free blocks
> over the entire file system or is the only option
> the cg-by-cg lookup?

afaik, cg by cg is how you'll have to do it.

- Alfred Perlstein
- Research Engineering Development Inc.
- email: bright at cell: 408-480-4684

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