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Bug 1600058

Summary: VDO can go read-only, lose sparsely-written data when parts are discarded. [rhel-7.5.z]
Product: Red Hat Enterprise Linux 7 Reporter: Jaroslav Reznik <jreznik>
Component: kmod-kvdoAssignee: vdo-internal <vdo-internal>
Status: CLOSED ERRATA QA Contact: Jakub Krysl <jkrysl>
Severity: unspecified Docs Contact: Marek Suchánek <msuchane>
Priority: high    
Version: 7.6CC: awalsh, jkrysl, knappch, limershe, rhandlin, ryan.p.norwood, sweettea
Target Milestone: rcKeywords: ZStream
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: 6.1.0.179 Doc Type: If docs needed, set a value
Doc Text:
Previously, VDO did not correctly reinitialize certain structures when a discard spanned logical addresses on two different block map trees. As a consequence, a discard operation sometimes switched the affected VDO volume to read-only mode or corrupted data on it in rare cases. With this update, VDO now reinitializes the structures correctly, and the described problem no longer occurs.
Story Points: ---
Clone Of: 1589249 Environment:
Last Closed: 2018-08-16 14:19:04 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1589249    
Bug Blocks:    

Description Jaroslav Reznik 2018-07-11 10:31:05 UTC
This bug has been copied from bug #1589249 and has been proposed to be backported to 7.5 z-stream (EUS).

Comment 3 Jakub Krysl 2018-07-24 13:53:36 UTC
tested with kvdo 6.1.0.181, could not hit the issue after 50 iterations. Original reproducer was able to hit it after 8.

Comment 5 Jakub Krysl 2018-08-09 14:29:15 UTC
Hi Marek,

Yes, it is correct.
Is seems a bit more serious than it really is, but I have no idea how to incorporate all the needed information and keep it short at the same time.
VDO max_discard_size is really small so a discard spanning 2 trees (one of which is not fully allocated) has really small chance of happening on default VDO device. Though it is possible to increase the max_discard_size, just afaik not documented anywhere, so not widely used. And even than it is not easy to reproduce...
I would leave it as it is for the sake of simplicity. :)

Thanks,
Jakub

Comment 6 Marek Suchánek 2018-08-09 14:31:54 UTC
OK, I'm adding "in rare cases" :-)

Comment 8 errata-xmlrpc 2018-08-16 14:19:04 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-2018:2450