Bug 1009993

Summary:	RHEL7 guests do not issue fdatasyncs on virtio-blk
Product:	Red Hat Enterprise Linux 7	Reporter:	Paolo Bonzini <pbonzini>
Component:	qemu-kvm	Assignee:	Paolo Bonzini <pbonzini>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	urgent	Docs Contact:
Priority:	high
Version:	7.0	CC:	acathrow, hhuang, juzhang, pbonzini, sluo, virt-maint, xfu
Target Milestone:	rc	Keywords:	Regression
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	-kvm-1.5.3-14.el7	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2014-06-13 12:37:38 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:

Description Paolo Bonzini 2013-09-19 16:21:37 UTC

Description of problem:
A RHEL7 guest is not issuing cache flush commands to a virtio-blk disk.

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


How reproducible:


Steps to Reproduce:
1. run QEMU with virtio disk and RHEL7, preceding the commandline with "strace -e fdatasync ff"

Actual results:
fdatasync syscalls issued only when QEMU exits

Expected results:
fdatasync syscalls issued during guest execution

Additional info:
The following sequence happens:
- the SeaBIOS virtio-blk driver does not support the WCE feature, which causes QEMU to disable writeback caching
- the Linux virtio-blk driver resets the device, finds WCE is available but writeback caching is disabled; tells block layer to not send cache flush commands
- the Linux virtio-blk driver sets the DRIVER_OK bit, which causes writeback caching to be re-enabled, but the Linux virtio-blk driver does not know of this side effect and cache flushes remain disabled

The fix is to re-enable writeback (according to the original value set in the "-drive" option) when the Linux virtio-blk driver resets the device.

Comment 2 juzhang 2013-09-26 03:16:28 UTC

Reproduced with qemu-kvm-rhev-1.5.3-6 with virtio-blk interface according to comment0

Comment 3 Miroslav Rezanina 2013-11-06 11:26:09 UTC

Fix included in -kvm-1.5.3-14.el7

Comment 5 FuXiangChun 2013-11-08 03:10:18 UTC

Verify this bug with qemu-kvm-1.5.3-14.el7.x86_64

steps:
1.Boot guest with cache=none
strace -e fdatasync -ff -o strace-output-file-none /usr/libexec/qemu-kvm...
 -drive file=xxxx,cache=none,werror=stop,rerror=stop,aio=threads -device virtio-blk-pci

2. search "fdatasync syscall issued" from strace-output-file-none* files

result:
# grep async strace-output-file-none*
strace-output-file-none.15171:fdatasync(9)                            = 0
strace-output-file-none.15171:fdatasync(9)                            = 0
strace-output-file-none.15178:fdatasync(9)                            = 0
strace-output-file-none.15179:fdatasync(9)                            = 0
strace-output-file-none.15179:fdatasync(9)                            = 0
strace-output-file-none.15179:fdatasync(9)                            = 0
strace-output-file-none.15180:fdatasync(9)                            = 0
strace-output-file-none.15180:fdatasync(9)                            = 0
strace-output-file-none.15180:fdatasync(9)                            = 0
strace-output-file-none.15180:fdatasync(9)                            = 0
strace-output-file-none.15181:fdatasync(9)                            = 0
strace-output-file-none.15181:fdatasync(9)                            = 0
strace-output-file-none.15182:fdatasync(9)                            = 0
strace-output-file-none.15182:fdatasync(9)                            = 0
strace-output-file-none.15182:fdatasync(9)                            = 0
strace-output-file-none.15182:fdatasync(9)                            = 0
strace-output-file-none.15182:fdatasync(9)                            = 0
strace-output-file-none.15183:fdatasync(9)                            = 0
strace-output-file-none.15183:fdatasync(9)                            = 0
strace-output-file-none.15184:fdatasync(9)                            = 0
strace-output-file-none.15185:fdatasync(9)                            = 0
strace-output-file-none.15186:fdatasync(9)                            = 0
strace-output-file-none.15187:fdatasync(9)                            = 0
strace-output-file-none.15187:fdatasync(9)                            = 0
strace-output-file-none.15187:fdatasync(9)                            = 0
strace-output-file-none.15189:fdatasync(9)                            = 0
strace-output-file-none.15189:fdatasync(9)                            = 0
strace-output-file-none.15190:fdatasync(9)                            = 0
strace-output-file-none.15190:fdatasync(9)                            = 0
strace-output-file-none.15190:fdatasync(9)                            = 0
strace-output-file-none.15190:fdatasync(9)                            = 0
strace-output-file-none.15190:fdatasync(9)                            = 0
strace-output-file-none.15191:fdatasync(9)                            = 0
strace-output-file-none.15191:fdatasync(9)                            = 0
strace-output-file-none.15192:fdatasync(9)                            = 0
strace-output-file-none.15192:fdatasync(9)                            = 0
strace-output-file-none.15193:fdatasync(9)                            = 0
strace-output-file-none.15193:fdatasync(9)                            = 0
strace-output-file-none.15194:fdatasync(9)                            = 0
strace-output-file-none.15194:fdatasync(9)                            = 0
strace-output-file-none.15195:fdatasync(9)                            = 0
strace-output-file-none.15195:fdatasync(9)                            = 0
strace-output-file-none.15196:fdatasync(9)                            = 0
strace-output-file-none.15196:fdatasync(9)                            = 0
strace-output-file-none.15223:fdatasync(9)                            = 0
strace-output-file-none.15224:fdatasync(9)                            = 0
strace-output-file-none.15224:fdatasync(9)                            = 0
strace-output-file-none.15225:fdatasync(9)                            = 0
strace-output-file-none.15226:fdatasync(9)                            = 0
strace-output-file-none.15226:fdatasync(9)                            = 0
strace-output-file-none.15227:fdatasync(9)                            = 0
strace-output-file-none.15228:fdatasync(9)                            = 0
strace-output-file-none.15228:fdatasync(9)                            = 0
strace-output-file-none.15229:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15230:fdatasync(9)                            = 0
strace-output-file-none.15231:fdatasync(9)                            = 0
strace-output-file-none.15231:fdatasync(9)                            = 0
strace-output-file-none.15231:fdatasync(9)                            = 0
strace-output-file-none.15232:fdatasync(9)                            = 0
strace-output-file-none.15232:fdatasync(9)                            = 0
strace-output-file-none.15232:fdatasync(9)                            = 0
strace-output-file-none.15232:fdatasync(9)                            = 0
strace-output-file-none.15232:fdatasync(9)                            = 0
strace-output-file-none.15235:fdatasync(9)                            = 0
strace-output-file-none.15235:fdatasync(9)                            = 0
strace-output-file-none.15236:fdatasync(9)                            = 0
strace-output-file-none.15237:fdatasync(9)                            = 0
strace-output-file-none.15237:fdatasync(9)                            = 0
strace-output-file-none.15237:fdatasync(9)                            = 0
strace-output-file-none.15242:fdatasync(9)                            = 0
strace-output-file-none.15242:fdatasync(9)                            = 0
strace-output-file-none.15242:fdatasync(9)                            = 0
strace-output-file-none.15242:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15243:fdatasync(9)                            = 0
strace-output-file-none.15257:fdatasync(9)                            = 0
strace-output-file-none.15257:fdatasync(9)                            = 0
strace-output-file-none.15258:fdatasync(9)                            = 0
strace-output-file-none.15258:fdatasync(9)                            = 0
strace-output-file-none.15264:fdatasync(9)                            = 0
strace-output-file-none.15264:fdatasync(9)                            = 0
strace-output-file-none.15304:fdatasync(9)                            = 0
strace-output-file-none.15304:fdatasync(9)                            = 0
strace-output-file-none.15305:fdatasync(9)                            = 0
strace-output-file-none.15305:fdatasync(9)                            = 0
strace-output-file-none.15305:fdatasync(9)                            = 0
strace-output-file-none.15305:fdatasync(9)                            = 0
strace-output-file-none.15306:fdatasync(9)                            = 0
strace-output-file-none.15306:fdatasync(9)                            = 0
strace-output-file-none.15306:fdatasync(9)                            = 0
strace-output-file-none.15306:fdatasync(9)                            = 0
strace-output-file-none.15306:fdatasync(9)                            = 0
strace-output-file-none.15306:fdatasync(9)                            = 0
strace-output-file-none.15307:fdatasync(9)                            = 0
strace-output-file-none.15307:fdatasync(9)                            = 0
strace-output-file-none.15307:fdatasync(9)                            = 0
strace-output-file-none.15307:fdatasync(9)                            = 0
strace-output-file-none.15308:fdatasync(9)                            = 0
strace-output-file-none.15308:fdatasync(9)                            = 0
strace-output-file-none.15308:fdatasync(9)                            = 0
strace-output-file-none.15308:fdatasync(9)                            = 0
strace-output-file-none.15308:fdatasync(9)                            = 0
strace-output-file-none.15308:fdatasync(9)                            = 0
strace-output-file-none.15309:fdatasync(9)                            = 0
strace-output-file-none.15309:fdatasync(9)                            = 0
strace-output-file-none.15309:fdatasync(9)                            = 0
strace-output-file-none.15310:fdatasync(9)                            = 0
strace-output-file-none.15310:fdatasync(9)                            = 0
strace-output-file-none.15310:fdatasync(9)                            = 0
strace-output-file-none.15310:fdatasync(9)                            = 0
strace-output-file-none.15311:fdatasync(9)                            = 0
strace-output-file-none.15311:fdatasync(9)                            = 0
strace-output-file-none.15311:fdatasync(9)                            = 0
strace-output-file-none.15311:fdatasync(9)                            = 0
strace-output-file-none.15312:fdatasync(9)                            = 0
strace-output-file-none.15312:fdatasync(9)                            = 0
strace-output-file-none.15312:fdatasync(9)                            = 0
strace-output-file-none.15313:fdatasync(9)                            = 0
strace-output-file-none.15313:fdatasync(9)                            = 0
strace-output-file-none.15313:fdatasync(9)                            = 0
strace-output-file-none.15313:fdatasync(9)                            = 0
strace-output-file-none.15316:fdatasync(9)                            = 0
strace-output-file-none.15316:fdatasync(9)                            = 0

3. Boot guest with cache=wirteback
strace -e fdatasync -ff -o strace-output-file /usr/libexec/qemu-kvm...
 -drive file=xxxx,cache=writeback,werror=stop,rerror=stop,aio=threads -device virtio-blk-pci

4. search "fdatasync syscall issued" from strace-output-file* files

result:
# grep async strace-output-file*
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15065:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15073:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15074:fdatasync(9)                            = 0
strace-output-file.15098:fdatasync(9)                            = 0
strace-output-file.15098:fdatasync(9)                            = 0
strace-output-file.15098:fdatasync(9)                            = 0
strace-output-file.15098:fdatasync(9)                            = 0
strace-output-file.15099:fdatasync(9)                            = 0
strace-output-file.15099:fdatasync(9)                            = 0
strace-output-file.15106:fdatasync(9)                            = 0
strace-output-file.15106:fdatasync(9)                            = 0
strace-output-file.15106:fdatasync(9)                            = 0
strace-output-file.15106:fdatasync(9)                            = 0
strace-output-file.15106:fdatasync(9)                            = 0
strace-output-file.15106:fdatasync(9)                            = 0
strace-output-file.15108:fdatasync(9)                            = 0
strace-output-file.15108:fdatasync(9)                            = 0
strace-output-file.15108:fdatasync(9)                            = 0
strace-output-file.15108:fdatasync(9)                            = 0
strace-output-file.15108:fdatasync(9)                            = 0
strace-output-file.15108:fdatasync(9)                            = 0
strace-output-file.15110:fdatasync(9)                            = 0
strace-output-file.15110:fdatasync(9)                            = 0
strace-output-file.15110:fdatasync(9)                            = 0
strace-output-file.15110:fdatasync(9)                            = 0
strace-output-file.15111:fdatasync(9)                            = 0
strace-output-file.15111:fdatasync(9)                            = 0
strace-output-file.15111:fdatasync(9)                            = 0
strace-output-file.15111:fdatasync(9)                            = 0
strace-output-file.15112:fdatasync(9)                            = 0
strace-output-file.15112:fdatasync(9)                            = 0
strace-output-file.15112:fdatasync(9)                            = 0
strace-output-file.15112:fdatasync(9)                            = 0
strace-output-file.15122:fdatasync(9)                            = 0
strace-output-file.15122:fdatasync(9)                            = 0
strace-output-file.15122:fdatasync(9)                            = 0
strace-output-file.15122:fdatasync(9)                            = 0
strace-output-file.15122:fdatasync(9)                            = 0
strace-output-file.15122:fdatasync(9)                            = 0
strace-output-file.15123:fdatasync(9)                            = 0
strace-output-file.15123:fdatasync(9)                            = 0
strace-output-file.15123:fdatasync(9)                            = 0
strace-output-file.15123:fdatasync(9)                            = 0
strace-output-file.15124:fdatasync(9)                            = 0
strace-output-file.15124:fdatasync(9)                            = 0
strace-output-file.15124:fdatasync(9)                            = 0
strace-output-file.15124:fdatasync(9)                            = 0
strace-output-file.15125:fdatasync(9)                            = 0
strace-output-file.15125:fdatasync(9)                            = 0
strace-output-file.15125:fdatasync(9)                            = 0
strace-output-file.15125:fdatasync(9)                            = 0
strace-output-file.15126:fdatasync(9)                            = 0
strace-output-file.15126:fdatasync(9)                            = 0
strace-output-file.15126:fdatasync(9)                            = 0
strace-output-file.15126:fdatasync(9)                            = 0
strace-output-file.15126:fdatasync(9)                            = 0
strace-output-file.15126:fdatasync(9)                            = 0
strace-output-file.15128:fdatasync(9)                            = 0
strace-output-file.15128:fdatasync(9)                            = 0
strace-output-file.15128:fdatasync(9)                            = 0
strace-output-file.15128:fdatasync(9)                            = 0
strace-output-file.15128:fdatasync(9)                            = 0
strace-output-file.15128:fdatasync(9)                            = 0
strace-output-file.15130:fdatasync(9)                            = 0
strace-output-file.15130:fdatasync(9)                            = 0
strace-output-file.15130:fdatasync(9)                            = 0
strace-output-file.15130:fdatasync(9)                            = 0
strace-output-file.15130:fdatasync(9)                            = 0
strace-output-file.15130:fdatasync(9)                            = 0
strace-output-file.15134:fdatasync(9)                            = 0
strace-output-file.15134:fdatasync(9)                            = 0
strace-output-file.15135:fdatasync(9)                            = 0
strace-output-file.15135:fdatasync(9)                            = 0
strace-output-file.15136:fdatasync(9)                            = 0
strace-output-file.15136:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15137:fdatasync(9)                            = 0
strace-output-file.15147:fdatasync(9)                            = 0
strace-output-file.15147:fdatasync(9)                            = 0
strace-output-file.15147:fdatasync(9)                            = 0
strace-output-file.15147:fdatasync(9)                            = 0
strace-output-file.15147:fdatasync(9)                            = 0
strace-output-file.15147:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15149:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15150:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15151:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0
strace-output-file.15152:fdatasync(9)                            = 0

Additional: search fdatasync syscalls issued during guest execution(not shutdown)

base on this test result above. this bug is fixed.

Comment 7 Ludek Smid 2014-06-13 12:37:38 UTC

This request was resolved in Red Hat Enterprise Linux 7.0.

Contact your manager or support representative in case you have further questions about the request.