By checking the mount status, we avoid remounting things if we don't
need to. And printing a single line per mount helps debugging when
things go wrong.
Closes: #859
Approved by: jlebon
I really have no idea what I was thinking with that list of mount points. It
seems arbitrary. Sadly `git log` doesn't help, and there's no comments.
Basically, the only mounts we should care about are those that libostree
creates. Which are just `/sysroot` and `/var`. Systemd will handle the other
things like `/tmp`, it's not our job, and we shouldn't touch them.
Closes: #859
Approved by: jlebon
In current systemd, there is:
[systemd-volatile-root](https://www.freedesktop.org/software/systemd/man/systemd-volatile-root.service.html)
which was introduced by [this commit](91214a37ef).
I'd like to make further changes to how we handle `/var`, and I don't
want to reason about the interaction of our "tmpfs var" with too many
other things.
The comment about having "all /var handling in one place" was always inaccurate
given that we rely on systemd for mounting. And in general, I don't want to
duplicate too many things systemd does - it does them well, documents them, etc.
As far as I know, it was basically just Owen who was using this for the GNOME
hardware testing effort, and I'm sure he could easily switch over to
`systemd.volatile=state`.
Closes: #856
Approved by: owtaylor
As $DEITY intended.
I was reading the `prepare-root.c` code and the indentation damage was
distracting. Squash tabs that have leaked into various places in the code. I
didn't yet touch the `src/libostree` bits as that has higher potential for
conflict.
Closes: #852
Approved by: jlebon
The `warn()` libc extension has exactly the same behaviour as our own
`perrorv` function, but is available in (at least) glibc and musl. As an
added bonus the similar function `err()` which will exit with an error
code afterwards.
This implementation is tidier and allows us to get rid of our own
`perrorv`. It paves the way to removing `ostree-mount-util.c` to simplify
the build scripts.
Original idea by @cgwalters in #477.
Closes: #478
Approved by: cgwalters
I'm trying to improve the developer experience on OSTree-managed
systems, and I had an epiphany the other day - there's no reason we
have to be absolutely against mutating the current rootfs live. The
key should be making it easy to rollback/reset to a known good state.
I see this command as useful for two related but distinct workflows:
- `ostree admin unlock` will assume you're doing "development". The
semantics hare are that we mount an overlayfs on `/usr`, but the
overlay data is in `/var/tmp`, and is thus discarded on reboot.
- `ostree admin unlock --hotfix` first clones your current deployment,
then creates an overlayfs over `/usr` persistent
to this deployment. Persistent in that now the initramfs switchroot
tool knows how to mount it as well. In this model, if you want
to discard the hotfix, at the moment you roll back/reboot into
the clone.
Note originally, I tried using `rofiles-fuse` over `/usr` for this,
but then everything immediately explodes because the default (at least
CentOS 7) SELinux policy denies tons of things (including `sshd_t`
access to `fusefs_t`). Sigh.
So the switch to `overlayfs` came after experimentation. It still
seems to have some issues...specifically `unix_chkpwd` is broken,
possibly because it's setuid? Basically I can't ssh in anymore.
But I *can* `rpm -Uvh strace.rpm` which is handy.
NOTE: I haven't tested the hotfix path fully yet, specifically
the initramfs bits.
/var needs to be read-write for a functioning system. Various
systemd services will fail to start if /var is read-only. After we
remount /var (or if we skip remounting /var because / is read-only),
if /var is still readonly, mount a tmpfs file system on /var.
While this isn't strictly part of ostree, keeping it here makes sense
because it keeps twiddling around with the /var mount in one place
for easier coordination and maintenance. This will likely need updating
if systemd gains better support for a readonly root filesystem.
https://bugzilla.gnome.org/show_bug.cgi?id=732979
The previous S_IMMUTABLE commit broke ostree-remount; / is now not
actually writable. All we really wanted to know though was whether it
was *mounted* writable, so check that via statvfs() which is cleaner
anyways (i.e. not via access() which kernel people hate).
https://bugzilla.gnome.org/show_bug.cgi?id=728006
Linux creates a copy of the soure mount flags when creating a bind
mount; if the source is read-only, then the bind mount is.
The problem is that systemd will remount the rootfs read/write, but
each mount (/home, /var etc.) will still be read-only. We need to
remount every bind mount except for /usr to read-write too.
This only "worked" with the old ostree-switch-root because it
effectively force mounted the rootfs read-write always, ignoring the
"ro" flag.
Colin Walters
William Manley
Giuseppe Scrivano
Owen W. Taylor