What does df command use to get "Used" column?

[Bruce Cran]

On Thu, 12 Mar 2009 15:59:54 -0700 (PDT)
Peter Steele <psteele at maxiscale.com> wrote:

> A typical df command looks like this: 
> 
> # df -h 
> Filesystem Size Used Avail Capacity Mounted on 
> /dev/mirror/gm0a 4.8G 2.0G 2.4G 46% / 
> devfs 1.0K 1.0K 0B 100% /dev 
> linprocfs 4.0K 4.0K 0B 100% /proc 
> /dev/mirror/gm0d 3.9G 88K 3.6G 0% /tmp 
> /dev/mirror/gm0e 15G 79M 13G 1% /var 
> /dev/ad4s3e 116G 2.3M 107G 0% /v0 
> /dev/ad6s3e 116G 2.2M 107G 0% /v1 
> /dev/ad8s3e 116G 2.1M 107G 0% /v2 
> /dev/ad10s3e 116G 2.1M 107G 0% /v3 
> 
> I know what calls to make to get the "Size" and "Avail" columns. I'm
> not sure what df does to get the value for the "Used" column. Anyone
> know how df gets this value? 

Line 417 of /usr/src/bin/df/df.c:

used = sfsp->f_blocks - sfsp->f_bfree;

-- 
Bruce