Arch Linux

Description:

With nbd@nbd0.service enabled and an nbd0 mount configured in nbdtab, the nbd@nbd0 enters a reboot loop:

Nov 21 11:06:16 localhost nbd-client[351]: Connected /dev/nbd0
...
Nov 21 11:28:21 localhost systemd[1]: Starting NBD client connection for nbd0...
Nov 21 11:28:21 localhost nbd-client[341]: Negotiation: ..size = 32768MB
Nov 21 11:28:21 localhost systemd[1]: nbd@nbd0.service: Control process exited, code=exited status=1
Nov 21 11:28:21 localhost nbd-client[341]: Error: Failed to setup device, check dmesg
Nov 21 11:28:21 localhost nbd-client[341]: Exiting.
Nov 21 11:28:21 localhost nbd_client[341]: Failed to setup device, check dmesg
Nov 21 11:28:21 localhost systemd[1]: nbd@nbd0.service: Failed with result 'exit-code'.
Nov 21 11:28:21 localhost nbd_client[341]: Exiting.
Nov 21 11:28:21 localhost systemd[1]: Failed to start NBD client connection for nbd0.

Following the advice and checking dmesg shows that /dev/nbd0 was already mounted:

[ 348.619470] nbd: nbd0 already in use

/dev/nbd0 is properly loaded, partitions and everything, so nbd@.service is failed on
a successful mount.

I suspect this is due to `Type=forking` and nbd not presenting a PIDFile to track the process,
but I'm not sure.

A quick and dirty workaround is to set ExecStart=/usr/bin/sh -c 'nbd-client -c %i || nbd-client %i',
which isn't perfect, but does converge.


Additional info:
* nbd 3.18-1


Steps to reproduce:

0. configure an nbd server instance exposing MOUNT
1. on client machine, add MOUNT to /etc/nbdtab, binding to nbd0
2. enable nbd@nbd0
3. reboot