Bug 1267671 - New snapshot Overflow status causes binary incompatibility
Summary: New snapshot Overflow status causes binary incompatibility
Keywords:
Status: CLOSED RAWHIDE
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: rawhide
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: ---
Assignee: Mike Snitzer
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2015-09-30 15:44 UTC by Zdenek Kabelac
Modified: 2016-05-26 19:21 UTC (History)
16 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2016-05-26 19:21:13 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)

Description Zdenek Kabelac 2015-09-30 15:44:12 UTC
Description of problem:

4.3 kernel introduce new state for overfilled snapshot.

pre 4.3 always reported 'Invalid' keyword.
4.3 can report 'Overflow' in certain cases.

Multiple ideas how to solve it:

1.) Kernel might detect 'API' version of user-space - and return flag according to this version -> lots of work in kernel.

2.) User-space might try to use new 'type'  (e.g. 'O') for snapshot which might be handled for overflow - means  new user space code understands this flag and can use it - this will however have miner problem with old binary running at the same time - but this case hardly ever happens - if new tool activated new snapshot - it's valid estimation this new tool will also handle it for monitoring and extending.

Version-Release number of selected component (if applicable):
4.3-rc2

How reproducible:


Steps to Reproduce:
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Actual results:


Expected results:


Additional info:

Comment 1 Mike Snitzer 2015-10-24 00:13:03 UTC
This has been fixed with these upstream commits:
b0d3cc011e5 ("dm snapshot: add new persistent store option to support overflow")
a2a678ed4d0 ("dm snapshot persistent: fix missing cleanup in persistent_ctr error path")

Comment 2 Josh Boyer 2015-10-26 14:15:15 UTC
The first is in 4.3-rc5, the second is in 4.3-rc5.  Rawhide should already contain these commits as of last week.

To be sure, 4.3-rc7 will likely be built today.  You could verify with that kernel tomorrow.


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