"install devtools" in F22 live boot, device-mapper implosion

[Chris Murphy]

User over on users@ list reports booting Fedora 22 Workstation (live
media), and doing:

# dnf install "Developer Tools"

Implodes.

I've reproduced the problem, and the gist is that there's a dm
snapshot that's too small for this task, it gets full quickly, the
file system face plants, and the kernel oopses. No recovery is
possible. Long version [1].

Question 1: Should this work better and be a supported use case?

Question 2: If so how to fix it? Change the configuration for a bigger
snapshot? Or use thin provisioning snapshot? Or overlayfs?

I haven't tested livecd-iso-to-disk --overlay-size-mb option, but I
give it better than even odds that for the baremetal case it will work
and might be a suitable work around. Thoughts?



[1]

If a bug should be filed, let me know what to file it against. I have
no idea what's responsible for the configuration of the install
media's live environment itself.

# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot 230544/1048576 912

# dnf group install "Development Tools"

## I allow metadata to download. Total metadata downloaded 41MB
(stable branch) and 13MB (updates branch).

# dmsetup status
[root at localhost ~]# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot 484016/1048576 1896

So the snapshot is filling up. Continue with download and install of
packages, while continue to check dmsetup status and eventually I get
to this:

[root at localhost ~]# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot 691048/1048576 2704
[root at localhost ~]# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot 703536/1048576 2752
[root at localhost ~]# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot 716320/1048576 2800
[root at localhost ~]# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot 716400/1048576 2800
[root at localhost ~]# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot 716464/1048576 2800
[root at localhost ~]# dmsetup status
live-base: 0 12582912 linear
live-osimg-min: 0 12582912 snapshot 3664/3664 24
live-rw: 0 12582912 snapshot Invalid
[root at localhost ~]# dmesg
-bash: /usr/bin/dmesg: Input/output error

Separately I had a journalctl -f running and it captures

[  928.709182] localhost kernel: device-mapper: snapshots:
Invalidating snapshot: Unable to allocate exception.

And then a long pile of ext4 errors.



-- 
Chris Murphy