Red Hat Bugzilla – Bug 1267671
New snapshot Overflow status causes binary incompatibility
Last modified: 2016-05-26 15:21:13 EDT
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):
Steps to Reproduce:
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")
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.