Bug #53885
closed
diff-iterate in fast-diff mode reports extents out of order for fancy striped images
Added by Ilya Dryomov over 2 years ago.
Updated almost 2 years ago.
Description
$ rbd create --size 20M --stripe-unit 1M --stripe-count 3 --thick-provision foo
Thick provisioning: 100% complete...done.
With fast-diff adjacent extents are reported out of order (and also aren't merged):
$ rbd diff foo
Offset Length Type
0 12582912 data
12582912 8388608 data
$ rbd diff --whole-object foo
Offset Length Type
0 1048576 data
3145728 1048576 data
6291456 1048576 data
9437184 1048576 data
1048576 1048576 data
4194304 1048576 data
7340032 1048576 data
10485760 1048576 data
2097152 1048576 data
5242880 1048576 data
8388608 1048576 data
11534336 1048576 data
12582912 1048576 data
15728640 1048576 data
18874368 1048576 data
13631488 1048576 data
16777216 1048576 data
19922944 1048576 data
14680064 1048576 data
17825792 1048576 data
This bug goes back to the introduction of fast-diff mode in 2015.
- Description updated (diff)
- Description updated (diff)
- Related to Bug #53784: diff-iterate reports incorrect offsets in fast-diff mode added
- Backport set to octopus,pacific
- Related to Bug #55025: [test] improve fancy striping coverage added
- Status changed from In Progress to Fix Under Review
- Pull request ID set to 45601
- Status changed from Fix Under Review to Pending Backport
- Copied to Backport #55057: octopus: diff-iterate in fast-diff mode reports extents out of order for fancy striped images added
- Copied to Backport #55058: pacific: diff-iterate in fast-diff mode reports extents out of order for fancy striped images added
This bug goes back to the introduction of fast-diff mode in 2015.
It turns out that this statement is too strong. While technically true, non fast-diff modes (default and later --whole-object) behaved more or less the same through octopus. In particular, in octopus, "rbd diff foo" and "rbd diff --whole-object foo" outputs are consistent -- adjacent extents are reported out of order and aren't merged across the board there.
Based on this, I'm rejecting octopus backport as fixing non fast-diff modes in addition to fast-diff mode would be quite involved and out of scope of this issue.
- Description updated (diff)
- Status changed from Pending Backport to Resolved
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