[RFC] mount can figure out fstype automatically

[Craig Rodrigues]

On Sat, Jul 08, 2006 at 09:05:51AM -0700, Sam Leffler wrote:
> Linux has -t auto; haven't looked at how it works.

I didn't want to implement -t auto, in
case that would confuse things in case someone gets around
to implementing autofs for FreeBSD, so I just used -t "".

> It appears you just try a series of fs types; can't you read the device
> to infer the filesystem?

I was thinking of doing something like that.  You can basically
get the same info by doing something like:

file - < /dev/ad0s1e
/dev/stdin: Unix Fast File system (little-endian)

file - < /dev/ad0s4
/dev/stdin: SGI XFS filesystem


I leaned away from this approach in mount(8) because:
- I didn't want to tie mount(8) to file(1)
- I didn't want to build up a table of known superblocks
  inside mount(8) because every time a new filesystem is
  added to FreeBSD, mount(8) would need to be updated

If there was a way, maybe at the GEOM or filesystem level to
"taste" what type of filesystem existed on a device, and/or
have a filesystem advertise what type of superblock it has,
then that would be a nice way to do it, but I couldn't figure
out a way to easily do it.


-- 
Craig Rodrigues        
rodrigc at crodrigues.org