installed system boots with root=/dev/bcache0 rather than root=UUID when root is bcache

Bug #1680591 reported by Scott Moser
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
curtin
Fix Released
Medium
Unassigned
curtin (Ubuntu)
Fix Released
Medium
Unassigned

Bug Description

In some debugging of another issue, we realized that installs with root on bcache such as in tests/vmtests/test_bcache_basic.py end up booting with root=/dev/bcache0 (or bcache*) rather than UUID=.

This is not good as bcache names are not guaranteed in any order.

The reason this was failing was that when we create a filesystem on /dev/bcache0 no symlinks would be updated in /dev/disk/by-uuid/. The lack of a by-uuid entry causes /etc/grub.d/10_linux to take the 'GRUB_DEVICE' path in

| if [ "x${GRUB_DEVICE_UUID}" = "x" ] || [ "x${GRUB_DISABLE_LINUX_UUID}" = "xtrue" ] \
| || ! test -e "/dev/disk/by-uuid/${GRUB_DEVICE_UUID}" \
| || ( test -e "${GRUB_DEVICE}" && uses_abstraction "${GRUB_DEVICE}" lvm ); then
| LINUX_ROOT_DEVICE=${GRUB_DEVICE}
| else
| LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
| fi

For other devices the /dev/disk/by-uuid entries were (we believe) being created by the the udev watches in /lib/udev/rules.d/60-block.rules. However, the watch there does not cover bcache devices.

## /lib/udev/rules.d/60-block.rules
| # watch metadata changes, caused by tools closing the device node which was opened for writing
| ACTION!="remove", SUBSYSTEM=="block", KERNEL=="loop*|nvme*|sd*|vd*|xvd*|pmem*", OPTIONS+="watch"

Related bugs:
 * bug 1680597: udev 60-block.rules does not watch bcache
 * bug 1676991: bcache mounts inconsistent after node reboots

Related branches

Scott Moser (smoser)
Changed in curtin:
status: New → Confirmed
importance: Undecided → Medium
Revision history for this message
Ryan Harper (raharper) wrote :

Can we link the kernel or grub issue as well? It'd be nice to make this not just a curtin install issue.

Scott Moser (smoser)
description: updated
description: updated
Changed in curtin (Ubuntu):
status: New → Confirmed
importance: Undecided → Medium
Scott Moser (smoser)
Changed in curtin:
status: Confirmed → Fix Committed
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package curtin - 0.1.0~bzr500-0ubuntu1

---------------
curtin (0.1.0~bzr500-0ubuntu1) artful; urgency=medium

  * New upstream snapshot.
    - Allow re-use of vmtest output
    - Fix stacked storage configurations with iSCSI (LP: #1683910)
    - vmtests: enable tests to apply storage config to validate clear_holders path
    - mdadm_stop: Add retry and additional steps to halt a resync
    - vmtests: Add Artful release and update classes
    - clear-holders: mdadm use /proc/mdstat to wait for array to stop (LP: #1682584)
    - uc16 curthooks: add 'network' key to config file (LP: #1685000)
    - Doc and makefile updates for build and test on new systems.
    - clear-holders: make bcache handler wait for device shutdown (LP: #1680409)
    - vmtest: Use utf-8 and fix pseudo test collect_output
    - vmtest: fix path to install log, and utilize the globally copied paths.
    - Copy curtin install log into target. (LP: #1684128)
    - vmtest: add in post-test log post-processing
    - vmtest: update source.list test
    - add recursive flag to do_umount, add --umount to block-meta
    - load_command_environment: fix strict flag, and unit tests.
    - block_meta: Attempt to mount by UUID= if possible (LP: #1676991)
    - Make systems with root on bcache use root=UUID=. (LP: #1680591)

 -- Scott Moser <email address hidden> Fri, 19 May 2017 16:57:07 -0400

Changed in curtin (Ubuntu):
status: Confirmed → Fix Released
Revision history for this message
Scott Moser (smoser) wrote : Fixed in Curtin 17.1

This bug is believed to be fixed in curtin in 17.1. If this is still a problem for you, please make a comment and set the state back to New

Thank you.

Changed in curtin:
status: Fix Committed → Fix Released
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