Why updatedb doesn't traverse my external HD?

[Marko Vojinovic]

On Saturday 24 December 2011 12:44:58 G.Wolfe Woodbury wrote:
> looking at the output of the mount command on F16, it lists tmpfs on
> /media. This is different from F14 and Gentoo, where /media is a regular
> directory.

Thanks for pointing this out! :-) Indeed, /media is explicitly mounted, rather 
than being an ordinary directory under /:

[root at Yoda ~]# mount | grep media
tmpfs on /media type tmpfs 
(rw,nosuid,nodev,noexec,relatime,rootcontext=system_u:object_r:mnt_t:s0,seclabel,mode=755)
/dev/sdb1 on /media/teraipo type ext4 
(rw,nosuid,nodev,relatime,seclabel,user_xattr,acl,barrier=1,data=ordered,uhelper=udisks)

the external HD is mounted as ext4 on in /media/teraipo, but /media itself is 
mounted(???) as tmpfs, and consequently updatedb doesn't traverse it.

> Look for the start up stuff that makes the mount and disable it, then
> /media will just be a directory.  However, the USB subsystem may not
> properly work.

Ok, after a small search I found that systemd mounts the /media directory 
explicitly. The relevant script is:

[root at Yoda ~]# cat /lib/systemd/system/media.mount
[Unit]
Description=Media Directory
Before=local-fs.target

[Mount]
What=tmpfs
Where=/media
Type=tmpfs
Options=mode=755,nosuid,nodev,noexec

It seems that this was done by design, specifically for this directory. Ok, 
next two questions:

(1) What is the proper place to customize this configuration? I want /media to 
be ext4, so that it doesn't get excluded by updatedb. I know I could 
reconfigure the /lib/systemd/system/media.mount, but that would probably be 
overwritten on update or something. How are these things meant to be 
customized?

(2) Why is /media being mounted like this? If I reconfigure it back to ext4, is 
anything else going to break?

I think we need an expert on systemd here... ;-) Would it be a good idea to 
start another thread for this?

Best, :-)
Marko