Bug 1718727 - Committing changes to the backing file over NBD fails with reopening files not supported
Summary: Committing changes to the backing file over NBD fails with reopening files no...
Keywords:
Status: NEW
Alias: None
Product: Red Hat Enterprise Linux Advanced Virtualization
Classification: Red Hat
Component: qemu-kvm
Version: 8.0
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Maxim Levitsky
QA Contact: Tingting Mao
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2019-06-10 06:01 UTC by Tingting Mao
Modified: 2019-11-05 09:04 UTC (History)
8 users (show)

Fixed In Version:
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Type: Bug
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Description Tingting Mao 2019-06-10 06:01:31 UTC
Description of problem:
Committing changes to the backing file over NBD fails with reopening files not supported.


Version-Release number of selected component (if applicable):
qemu-kvm-4.0.0-3.module+el8.1.0+3265+26c4ed71
kernel-4.18.0-95.el8


How reproducible:
100%


Steps to Reproduce:
1. Create base image and export it by NBD
# qemu-img create -f raw test.img 2G
# qemu-nbd -f raw -p 9000 -t test.img --shared=2

2. Create snapshot file based on it
# qemu-img create -f qcow2 -b nbd:localhost:9000 sn.qcow2
# qemu-img info sn.qcow2 
image: sn.qcow2
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 196K
cluster_size: 65536
backing file: nbd:localhost:9000
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16
    corrupt: false

3. Write new data to the snapshot file
# qemu-io -c 'write -P 1 0 1G' sn.qcow2 
wrote 1073741824/1073741824 bytes at offset 0
1 GiB, 1 ops; 0:00:06.33 (161.573 MiB/sec and 0.1578 ops/sec)

4. Commit the changes
# qemu-img commit -f qcow2 sn.qcow2 -p
    (0.00/100%)
qemu-img: Block format 'nbd' used by node '#block238' does not support reopening files


Actual results:
Commit failed with above error.


Expected results:
Commit successfully.


Additional info:

Comment 1 Maxim Levitsky 2019-10-01 08:28:49 UTC
Patch posted upstream
https://lists.gnu.org/archive/html/qemu-block/2019-09/msg01448.html

Also note that bugs 1465320 and 1713647, and maybe more are duplicate of this.


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