Bug 88645

Summary:	MSG: nspawn: improve error text if --template= is used with non-btrfs file system
Product:	systemd	Reporter:	Elias Probst <mail>
Component:	general	Assignee:	systemd-bugs
Status:	RESOLVED FIXED	QA Contact:	systemd-bugs
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Elias Probst 2015-01-21 00:10:08 UTC

Kernel: 3.18.2 with btrfs builtin
systemd git 72521ab

rootfs of "host": ext4

Running
systemd-nspawn -b -D /media/test-intra --template=/media/centos7-base

fails with:
Couldn't create snapshot /media/test-intra from /media/centos7-base: Inappropriate ioctl for device

This looks to me like systemd-nspawn doesn't verify whether the FS providing -D is btrfs or not and just blindly tries to create a btrfs snapshot on top of it.


IMHO this needs at least to be handled a bit more graceful - letting the user know what's the problem.

Besides that, if there's no sane way to create a btrfs snapshot (e.g. using an image file) on top of another filesystem, this should be made clear in the systemd-nspawn manpage.

Comment 1 Lennart Poettering 2015-02-04 13:54:45 UTC

I am pretty sure we should issue the ioctl always, regardless what the backing fs is. Maybe one day the ioctls for snapshotting become generically used...

We can certainly improve the log message though, and tell the use that he needs btrfs as source if we encounter ENOTTY here...

Comment 2 Lennart Poettering 2016-11-24 01:06:32 UTC

nspawn in current git now supports --template= on non-btrfs file systems, hence this bug is probably obsolete. Closing.

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