DragonFlyBSD

Doing this is easy enough, and we only support three FS as root anyways (?)
(hammer, ffs/ufs, cd9660). I'd suggest adding a method to vfsops called vfs_probe
that will probe a given device name just to see if the filesystem on it matches
the vfs.

We already have vfsconf_each() which could then be used in sys/kern/vfs_conf.c to
iterate through all available filesystems and call their respective vfs_probe()
method until one of them returns no error.

To minimize the impact this might have on the boot time this should only be done
if no fs is specified in the vfs.root.mountfrom.

Any thoughts?

Cheers,
Alex Hornung

:We already have vfsconf_each() which could then be used in sys/kern/vfs_conf.c to
:iterate through all available filesystems and call their respective vfs_probe()
:method until one of them returns no error.
:
:To minimize the impact this might have on the boot time this should only be done
:if no fs is specified in the vfs.root.mountfrom.
:
:Any thoughts?
:
:Cheers,
:Alex Hornung

The disklabel also has the filesystem type stored in it for each
    partition.  The mount command can just probe that.  We can add an
    ioctl if necessary.

I would rather NOT try to auto-probe filesystems since different
    filesystems put their volume header in different places.  For example,
    it is possible for both the UFS and HAMMER volume headers to be present
    (I've done it), though of course only one of the two will actually be
    the correct filesystem.

-Matt

Not all partitions have a disklabel, so it would be somewhat limited.

I think a solution to this would be the hammer newfs and UFS newfs
overwriting enough of the first few blocks to avoid this from occurring...

Cheers,
Alex