Bug 701911

Summary:	file is changed after convert/rebase/commit operation
Product:	Red Hat Enterprise Linux 5	Reporter:	Suqin Huang <shuang>
Component:	kvm	Assignee:	Kevin Wolf <kwolf>
Status:	CLOSED WONTFIX	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	5.7	CC:	gcosta, juzhang, mkenneth, rhod, tburke, virt-maint
Target Milestone:	rc	Keywords:	Rebase, Reopened
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Rebase: Bug Fixes and Enhancements
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-10-31 10:18:19 UTC	Type:	---
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:
Bug Blocks:	580946

Description Suqin Huang 2011-05-04 09:20:24 UTC

Description of problem:


Version-Release number of selected component (if applicable):

kvm-83-232.el5

How reproducible:
sometime

Steps to Reproduce:
1. boot guest and create big file in guest
cmd:

qemu-kvm -drive file='/usr/images/RHEL-Server-6.1-64-virtio.qcow2',index=0,if=virtio,media=disk,cache=none,boot=on,format=qcow2 -net nic,vlan=0,model=virtio,macaddr='9a:96:a2:e2:19:33' -net tap,vlan=0,script='/usr/scripts/qemu-ifup-switch',downscript='no' -m 8192 -smp 4,cores=1,threads=1,sockets=4 -cpu qemu64,+sse2 -soundhw ac97 -spice port=8000,disable-ticketing -qxl 1 -rtc-td-hack -M rhel5.6.0 -boot c  -usbdevice tablet -no-kvm-pit-reinjection

2. dd if=/dev/zero of=/tmp/file_base bs=100M count=10

3. get file md5sum value and shutdown guest
   # md5sum /tmp/file_base

4. create snapshot
qemu-img create -b RHEL-Server-6.1-64-virtio.qcow2 -F qcow2 -f qcow2 sn1.qcow2

5. boot snapshot and create big file
# dd if=/dev/zero of=/tmp/sn1 bs=100M count=10
# md5sum /tmp/sn1

6. shutdown snapshot and sn1 
qemu-img convert -f qcow2 -O qcow2 /usr/sn1.qcow2 /usr/sn1.qcow2_to_qcow2.qcow2

7. check file after convert
# md5sum /tmp/sn1
# md5sum /tmp/file_base


Actual results:

md5sum value is changed after image converted, rebase/commit may also cause image changed

Expected results:


Additional info:

1. host
2.6.18-259.el5

processor	: 7
vendor_id	: AuthenticAMD
cpu family	: 16
model		: 4
model name	: Quad-Core AMD Opteron(tm) Processor 2376
stepping	: 2
cpu MHz		: 800.000
cache size	: 512 KB
physical id	: 1
siblings	: 4
core id		: 3
cpu cores	: 4
apicid		: 7
initial apicid	: 7
fpu		: yes
fpu_exception	: yes
cpuid level	: 5
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nonstop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt npt lbrv svm_lock nrip_save
bogomips	: 4588.58
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

Comment 3 Glauber Costa 2011-05-25 16:54:03 UTC

Until more information can be provided, this looks like just a wrong setup.

Comment 4 Suqin Huang 2011-06-20 02:28:37 UTC

Hi Glauber,
I don't compare file_base with sn1, I compare file_base_before_rebase with file_base_after_rebase, sn1 with sn1 (before and after), so, it should be a bug, can I re-open this bug

Comment 5 Kevin Wolf 2011-06-22 08:30:58 UTC

Have you tried if it happens on RHEL 6, too?

Comment 6 Kevin Wolf 2011-06-22 09:34:41 UTC

And can you verify that the md5sum is still the same when you restart the original VM?

Comment 7 Suqin Huang 2011-06-22 09:39:05 UTC

(In reply to comment #5)
> Have you tried if it happens on RHEL 6, too?

there is a bug for rhel6 bug 696557

Comment 9 Kevin Wolf 2011-08-01 16:28:41 UTC

(In reply to comment #6)
> And can you verify that the md5sum is still the same when you restart the
> original VM?

Did you check this?

Comment 10 Suqin Huang 2011-08-04 11:39:43 UTC

Test commit scenario, md5sum is still changed when boot base image

Comment 11 Kevin Wolf 2011-08-04 12:07:35 UTC

So is the md5sum of the original VM the same as on the copy after qemu-img convert? If so, this is not a bug in qemu-img, but the data has never been written correctly to the image file.

How do you shut the guest down after dd? Is it a clean shutdown or is qemu killed?

Comment 12 Suqin Huang 2011-08-05 01:43:39 UTC

(In reply to comment #11)
> So is the md5sum of the original VM the same as on the copy after qemu-img
> convert? If so, this is not a bug in qemu-img, but the data has never been
> written correctly to the image file.
> 

1. if don't do commit, then reboot base image, the md5sum is always the same
2. if commit, then reboot base image, the file md5sum is changed sometime.

> How do you shut the guest down after dd? Is it a clean shutdown or is qemu
> killed?

clean shutdown

Comment 13 Ronen Hod 2011-10-31 10:18:19 UTC

Since we didn't find the capacity to fix it for 5.8, it doesn't make sense to
continue dragging it to the next version. Closing.