| Summary: | [Regression] Prompt error of trigger blkdebug: BLKDBG_CLUSTER_FREE event is not the same as expected | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Qunfang Zhang <qzhang> |
| Component: | qemu-kvm | Assignee: | Hanna Czenczek <hreitz> |
| Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> |
| Severity: | medium | Docs Contact: | |
| Priority: | high | ||
| Version: | 6.5 | CC: | areis, bsarathy, chayang, hhuang, hreitz, juzhang, kwolf, mazhang, michen, mkenneth, rbalakri, sluo, virt-maint |
| Target Milestone: | rc | Keywords: | Regression |
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | qemu-kvm-0.12.1.2-2.425.el6 | Doc Type: | Bug Fix |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2014-10-14 06:53:50 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: | |
| Bug Depends On: | |||
| Bug Blocks: | 1056252 | ||
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Description
Qunfang Zhang
2013-10-28 07:55:52 UTC
I bisected this to downstream commit f0d6b82f ('block: Produce zeros when
protocols reading beyond end of file'). As it's not completely obvious,
understanding how this change broke the error message would require some more
investigation.
In any case, this is about internal snapshots, which we consider unsupported,
and a rather minor impact (reporting "Operation not supported" instead of the real
error). While this is a regression technically, I don't think there's a reason
to treat this as a blocker as long as no customer complains.
I recommend moving this bug to 6.6.
(Also CCing Max who did some upstream fixes related to the patch in question)
I personally find it much more interesting that I'm not able to use blkdebug on top of qcow2 at all – qemu-io always returns EIO for me and the BDS chain does not seem to involve qcow2 at all (which explains the ENOTSUP for deleting the snapshot). I tracked the problem to bdrv_check_byte_request() which checks the request against the length of the block device. bdrv_getlength() always returns 0 for the blkdebug, which is not suprising considering blkdebug does not implement that function downstream. Backporting e1302255 fixes this and therefore qemu-io can finally successfully read from a qcow2 image with blkdebug. This fixes the problem described in this bugzilla as well – I guess format detection simply did not work with blkdebug always reporting an empty image file and subsequently snapshot operations could not be executed. Fix included in qemu-kvm-0.12.1.2-2.425.el6 Verified pass on qemu-kvm-0.12.1.2-2.428.el6.x86_64 with the same steps in comment 0. Result: After step 5: [root@localhost qzhang]# qemu-img snapshot -d disk_snap blkdebug:blkdebug.cfg:disk.qcow2 qcow2_free_clusters failed: No space left on device Could not delete snapshot 'disk_snap': -28 (No space left on device) So, this bug is fixed. 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. http://rhn.redhat.com/errata/RHBA-2014-1490.html |