#46 Editing mount point options in Gnome disk utility renders system unbootable
Opened a year ago by neowave. Modified a year ago

Hello. I'm new to Fedora (and Linux in general,) and I've been playing around with Silverblue recently. I wanted the secondary drive in my system to mount automatically at startup because I noticed it wasn't. I used the Gnome disk utility, ungreyed the options and checked the box to automatically mount at startup. I also changed "identify as" to a label I set for the drive rather than the random string of characters it used to be. To test it out, I rebooted system and was met with the "F" logo slowly filling up, but never quite making it. This usually works fine in the non-Silverblue Fedora workstations, but it seems bugged here.

snapshot: https://postimg.cc/ykQqtDb5


Hmm. I'm guessing this has something to do with symlinks; see https://github.com/systemd/systemd/pull/6293

The systemd journal should have more useful error messages here, journalctl |grep fstab perhaps.

I poked around with this problem in a VM, using the steps described by @neowave. I was able to reproduce the problem as described.

I used rd.break enforcing=0 as kernel args after rebooting, so I could edit /etc/fstab and alter some of the options for the secondary disk. After booting into the initramfs (due to the use of rd.break):

# mount -o remount,rw /sysroot/
# chroot /sysroot/ostree/boot.0/fedora-workstation/ac11951e4d0add8abf633d461de9739b56d63355462c88f2ce2a31fd7955a165/0/
# vi /etc/fstab

The default line in /etc/fstab for the secondary disk looked like this:

LABEL=extra_disk /mnt/extra_disk auto nosuid,nodev,nofail,x-gvfs-show 0 0

I tried changing a number of the options, but nothing seemed to make any difference until I changed the mount point to /var/mnt/extra_disk

This allowed me to successfully mount the second disk during boot.

Do we have to further alter the fstab-generator to understand the use of /var/mnt on ostree systems?

The problem is SELinux policy:

Oct 08 14:31:05 localhost.localdomain audit[1]: AVC avc:  denied  { getattr } for  pid=1 comm="systemd" path="/mnt" dev="dm-0" ino=33554545 scontext=system_u:system_r:init_t:s0 tcontext=system_u:object_r:mnt_t:s
0 tclass=lnk_file permissive=0
Oct 08 14:30:51 localhost.localdomain audit[3176]: AVC avc:  denied  { getattr } for  pid=3176 comm="systemd-fstab-g" path="/mnt" dev="dm-0" ino=33554545 scontext=system_u:system_r:init_t:s0 tcontext=system_u:ob
ject_r:mnt_t:s0 tclass=lnk_file permissive=0

This is easier to debug if you avoid rebooting, just add the mount to /etc/fstab then systemctl daemon-reload. You'll see the new generated mount unit in /run/systemd/generator, like mnt-foo.mount for /mnt/foo.

Trying to systemctl start mnt-foo.mount crashes systemd here as it's not expecting denials.

Sorry for the delay. I can confirm that @miabbott's suggestion to set mount point to /var/mnt/another_disk works. the system boots just fine and mounts the 2nd disk automatically. Thanks for the help!

It also seems that @walters has found the root issue and filed a bug report on Red Hat's Bugzilla. Is it safe to close this now?

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