Bug 1366446
| Summary: | vol-resize with --shrink and --allocate behaves strangely | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 7 | Reporter: | Lili Zhu <lizhu> |
| Component: | libvirt | Assignee: | Ján Tomko <jtomko> |
| Status: | CLOSED ERRATA | QA Contact: | yisun |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 7.3 | CC: | dyuan, rbalakri, xuzhang, yisun, zpeng |
| Target Milestone: | rc | ||
| Target Release: | 7.3 | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | libvirt-3.8.0-1.el7 | Doc Type: | If docs needed, set a value |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2018-04-10 10:36:45 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: | |
| Embargoed: | |||
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Description
Lili Zhu
2016-08-12 02:09:49 UTC
For the additional info part: If I want to allocate the capacity, there is no necessity to using the shrink flag # virsh vol-resize /var/lib/libvirt/images/volds 4G --allocate Size of volume 'volds' successfully changed to 4G # qemu-img info /var/lib/libvirt/images/volds image: /var/lib/libvirt/images/volds file format: raw virtual size: 5.0G (5368709120 bytes) disk size: 4.0G What I mean actually is When I execute the above step 5 “successfully“, then I continue to execute the following command. there is no necessity to using the shrink flag at this time, and it will give the the following results # virsh vol-resize /var/lib/libvirt/images/volds 4G --allocate Size of volume 'volds' successfully changed to 4G # qemu-img info /var/lib/libvirt/images/volds image: /var/lib/libvirt/images/volds file format: raw virtual size: 5.0G (5368709120 bytes) disk size: 4.0G If we treat the RESIZE_ALLOCATE flag as "Make sure that the added difference" is allocated, then mixing it with RESIZE_SHRINK does not make sense. However we try to treat RESIZE_ALLOCATE as "make sure that the whole new size is allocated" and in that case shrinking should work too. Upstream series to fix the allocation behavior: https://www.redhat.com/archives/libvir-list/2017-September/msg00875.html Pushed upstream as:
commit 959fe7de1f0f6fadb86e853edead6d32c3cb3559
Author: Ján Tomko <jtomko>
CommitDate: 2017-09-27 14:40:44 +0200
Shrink volume even with ALLOCATE flag
Calling fallocate on the new (smaller) capacity ensures
that the whole file is allocated, but it does not reduce
the file size.
Also call ftruncate after fallocate.
https://bugzilla.redhat.com/show_bug.cgi?id=1366446
git describe: v3.7.0-183-g959fe7de1
test with libvirt-3.8.0-1.virtcov.el7.x86_64 According to comment 3, now the behaviour should be like: when do --allocate and --shrink together, file will be allocated (by fallocate) and shrunk (by ftruncate). And the test result satisfies the expectation: 1. prepare a 5G sparse file ## qemu-img create -f raw /var/lib/libvirt/images/5G.raw 5g Formatting '/var/lib/libvirt/images/5G.raw', fmt=raw size=5368709120 ## virsh pool-refresh default Pool default refreshed ## qemu-img info /var/lib/libvirt/images/5G.raw image: /var/lib/libvirt/images/5G.raw file format: raw virtual size: 5.0G (5368709120 bytes) disk size: 0 2. resize the image to 3.0 with --allocate (without --shrink) ## virsh vol-resize /var/lib/libvirt/images/5G.raw 3G --allocate error: Failed to change size of volume '5G.raw' to 3G error: invalid argument: Can't shrink capacity below current capacity unless shrink flag explicitly specified <== failed as expected ## qemu-img info /var/lib/libvirt/images/5G.raw image: /var/lib/libvirt/images/5G.raw file format: raw virtual size: 5.0G (5368709120 bytes) disk size: 0 <== not changed 2. resize the image to 3.0 with --allocate and --shrink ## virsh vol-resize /var/lib/libvirt/images/5G.raw 3G --allocate --shrink Size of volume '5G.raw' successfully changed to 3G ## qemu-img info /var/lib/libvirt/images/5G.raw image: /var/lib/libvirt/images/5G.raw file format: raw virtual size: 3.0G (3221225472 bytes) disk size: 3.0G <== both 'virtual size' and 'disk size' change to 3G as expected 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/RHEA-2018:0704 |