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Bug 2013916

Summary: virt-sparsify fails with the error: Backing file specified without backing format
Product: Red Hat Enterprise Linux 8 Reporter: YongkuiGuo <yoguo>
Component: libguestfsAssignee: Virtualization Maintenance <virt-maint>
Status: CLOSED ERRATA QA Contact: YongkuiGuo <yoguo>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 8.6CC: rjones, virt-maint
Target Milestone: rcKeywords: Triaged
Target Release: ---Flags: pm-rhel: mirror+
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: libguestfs-1.44.0-4.el8 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2022-05-10 13:21:40 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:
Bug Depends On: 1998820    
Bug Blocks:    

Description YongkuiGuo 2021-10-14 06:15:07 UTC 
Description of problem:
virt-sparsify doesn't work on RHEL-8.6 with the following error:
...
qemu-img: /tmp/sparsify187700.qcow2: Backing file specified without backing format
Detected format of qcow2.libguestfs: trace: disk_create = -1 (error)
virt-sparsify: error: libguestfs error: qemu-img:
/tmp/sparsify187700.qcow2: qemu-img exited with error status 1, see debug
messages above


Version-Release number of selected component (if applicable):
libguestfs-1.44.0-3.module+el8.6.0+12648+6ede71a5.x86_64
qemu-kvm-6.1.0-1.module+el8.6.0+12648+6ede71a5.x86_64


How reproducible:
100%


Steps:

1. On rhel8.6 host with RHEL-8.6.0-20211008.1 compose
# wget http://download.eng.pek2.redhat.com/rhel-8/composes/RHEL-8/RHEL-8.6.0-20211008.1/compose/BaseOS/x86_64/images/rhel-guest-image-8.6-493.x86_64.qcow2

2.
# virt-sparsify -v -x rhel-guest-image-8.6-493.x86_64.qcow2 outdisk 
libguestfs: trace: set_verbose true
libguestfs: trace: set_verbose = 0
libguestfs: trace: disk_format "/home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2"
libguestfs: command: run: qemu-img --help | grep -sqE -- '\binfo\b.*-U\b'
libguestfs: command: run: qemu-img
libguestfs: command: run: \ info
libguestfs: command: run: \ -U
libguestfs: command: run: \ --output json
libguestfs: command: run: \ /home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2
libguestfs: parse_json: qemu-img info JSON output:\n{\n    "virtual-size": 10737418240,\n    "filename": "/home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2",\n    "cluster-size": 65536,\n    "format": "qcow2",\n    "actual-size": 779419648,\n    "format-specific": {\n        "type": "qcow2",\n        "data": {\n            "compat": "0.10",\n            "compression-type": "zlib",\n            "refcount-bits": 16\n        }\n    },\n    "dirty-flag": false\n}\n\n
libguestfs: trace: disk_format = "qcow2"
libguestfs: trace: set_verbose true
libguestfs: trace: set_verbose = 0
libguestfs: trace: disk_virtual_size "/home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2"
libguestfs: command: run: qemu-img --help | grep -sqE -- '\binfo\b.*-U\b'
libguestfs: command: run: qemu-img
libguestfs: command: run: \ info
libguestfs: command: run: \ -U
libguestfs: command: run: \ --output json
libguestfs: command: run: \ /home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2
libguestfs: parse_json: qemu-img info JSON output:\n{\n    "virtual-size": 10737418240,\n    "filename": "/home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2",\n    "cluster-size": 65536,\n    "format": "qcow2",\n    "actual-size": 779419648,\n    "format-specific": {\n        "type": "qcow2",\n        "data": {\n            "compat": "0.10",\n            "compression-type": "zlib",\n            "refcount-bits": 16\n        }\n    },\n    "dirty-flag": false\n}\n\n
libguestfs: trace: disk_virtual_size = 10737418240
input disk virtual size is 10737418240 bytes (10.0G)
[   0.0] Create overlay file in /tmp to protect source disk
libguestfs: trace: set_verbose true
libguestfs: trace: set_verbose = 0
libguestfs: trace: disk_create "/tmp/sparsify187700.qcow2" "qcow2" -1 "backingfile:/home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2" "compat:1.1"
libguestfs: command: run: qemu-img
libguestfs: command: run: \ create
libguestfs: command: run: \ -f qcow2
libguestfs: command: run: \ -o backing_file=/home/git/libguestfs-ci/client/tests/libguestfs/rhel-guest-image-8.6-493.x86_64.qcow2,compat=1.1
libguestfs: command: run: \ /tmp/sparsify187700.qcow2
qemu-img: /tmp/sparsify187700.qcow2: Backing file specified without backing format
Detected format of qcow2.libguestfs: trace: disk_create = -1 (error)
virt-sparsify: error: libguestfs error: qemu-img:
/tmp/sparsify187700.qcow2: qemu-img exited with error status 1, see debug
messages above
libguestfs: trace: close
libguestfs: closing guestfs handle 0x557cde3691a0 (state 0)
libguestfs: trace: close
libguestfs: closing guestfs handle 0x557cde367970 (state 0)
libguestfs: trace: close
libguestfs: closing guestfs handle 0x557cde366300 (state 0)

Actual results:
As above

Expected results:
virt-sparsify works on RHEL-8.6 as usual.

Additional info:
No this issue on RHEL-8.5 and RHEL-9.0
Comment 1 Richard W.M. Jones 2021-10-14 07:30:49 UTC 
We'll need the same fix as:
https://bugzilla.redhat.com/show_bug.cgi?id=1999419 (RHEL 9)
https://bugzilla.redhat.com/show_bug.cgi?id=1998820 (upstream)

Upstream fix is:
https://github.com/libguestfs/libguestfs/commit/45de287447bb18d59749fbfc1ec5072413090109
Comment 5 YongkuiGuo 2021-10-15 10:30:08 UTC 
Verified with package:
libguestfs-1.44.0-4.module+el8.6.0+12969+f61072d9.x86_64

Steps:

1. On rhel8.6 host
# wget http://download.eng.pek2.redhat.com/rhel-8/composes/RHEL-8/RHEL-8.6.0-20211008.1/compose/BaseOS/x86_64/images/rhel-guest-image-8.6-493.x86_64.qcow2

2.
# virt-sparsify rhel-guest-image-8.6-493.x86_64.qcow2 outdisk
[   7.0] Fill free space in /dev/sda2 with zero
[   8.3] Fill free space in /dev/sda3 with zero
[  88.0] Copy to destination and make sparse
[ 148.4] Sparsify operation completed with no errors.
virt-sparsify: Before deleting the old disk, carefully check that the 
target disk boots and works correctly.


virt-sparsify can be run successfully.
Comment 7 errata-xmlrpc 2022-05-10 13:21:40 UTC 
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 (Moderate: virt:rhel and virt-devel:rhel security, bug fix, and enhancement update), 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/RHSA-2022:1759