Bug 1521163

Summary:	[RFE] blkid can identify magic number and UUID of VDO volume
Product:	Red Hat Enterprise Linux 7	Reporter:	Dennis Keefe <dkeefe>
Component:	util-linux	Assignee:	Karel Zak <kzak>
Status:	CLOSED ERRATA	QA Contact:	Radka Brychtova <rskvaril>
Severity:	low	Docs Contact:
Priority:	low
Version:	7.6	CC:	kzak, ovasik, rskvaril, sweettea
Target Milestone:	rc	Keywords:	FutureFeature
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	util-linux-2.23.2-49.el7	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-04-10 17:27:15 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Dennis Keefe 2017-12-05 22:02:02 UTC

Description of problem:
VDO is a device mapper target with deduplication and compression features.
Until recently VDO did not have a magic number or UUID.  blkid support for VDO
is needed, so utilities using blkid can be informed that the a given storage device is being used by VDO.


Version-Release number of selected component (if applicable):


How reproducible:
100% can't identify VDO volumes
Create a VDO volume


Steps to Reproduce:
1. vdo create --name=vdo1 --device=/dev/sdb --vdoLogicalSize=10T
2. # blkid /dev/sdb


Actual results:
# blkid /dev/sdb
# <nothing>

Expected results:
# blkid /dev/sdb
# /dev/sdb: UUID="<string>" TYPE="VDO"

Additional info:

Comment 3 Sweet Tea Dorminy 2017-12-05 22:04:27 UTC

The magic number is the first 8 bytes, with value 'dmvdo001' of the volume; the UUID is the 16 bytes starting 40 bytes into the volume. I could probably draw up quickly a superblocks/vdo.c if desired.

Comment 4 Karel Zak 2017-12-06 09:53:42 UTC

(In reply to Sweet Tea Dorminy from comment #3)
> I could probably draw up quickly a superblocks/vdo.c if desired.

Thanks! It would be nice. The ideal solution is to prepare a patch for upstream tree:

   https://github.com/karelzak/util-linux

I'll backport it to RHEL7. See also libblkid/src/superblocks/lvm.c where are another DM targets, maybe we can add DM_VDO there.

It would be also nice to have a test image with the superblock (just dd(1) first sectors from the device).

Comment 5 Sweet Tea Dorminy 2017-12-07 01:29:23 UTC

https://github.com/karelzak/util-linux/pull/547

Comment 14 errata-xmlrpc 2018-04-10 17:27:15 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:0936