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Bug 894253 - Missing error message in bdrv_commit to read-only backing file
Summary: Missing error message in bdrv_commit to read-only backing file
Keywords:
Status: CLOSED UPSTREAM
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm
Version: 7.0
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Jeff Cody
QA Contact: Virtualization Bugs
URL:
Whiteboard:
: 894250 894251 (view as bug list)
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-01-11 08:19 UTC by Sibiao Luo
Modified: 2013-08-27 21:41 UTC (History)
13 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of: 856505
Environment:
Last Closed: 2013-08-27 21:41:06 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Comment 1 Sibiao Luo 2013-01-11 08:25:07 UTC 
host info:
# uname -r && rpm -q qemu-kvm
3.6.0-0.29.el7.x86_64
qemu-kvm-1.3.0-3.el7.x86_64
guest info
# uname -r
3.6.0-0.29.el7.x86_64

Steps:
1. boot up guest with a readonly=on data image with snapshot=on.
e.g:...-drive file=/home/my-data-disk.qcow2,if=none,format=qcow2,id=drive-virtio0-0-0,media=disk,cache=none,readonly=on,snapshot=on -device virtio-blk-pci,bus=pci.0,addr=0x8,drive=drive-virtio0-0-0,id=virtio0-0-0
2. dd a file in the guest to the data disk.
3. do commit in monitor.
(qemu) info block
drive-system-disk: removable=0 io-status=ok file=/home/RHEL-7-Server-x86_64.qcow2 ro=0 drv=qcow2 encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0
drive-virtio0-0-0: removable=0 io-status=ok file=/tmp/vl.jpdcow backing_file=/home/my-data-disk.qcow2 backing_file_depth=1 ro=0 drv=qcow2 encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0
ide1-cd0: removable=1 locked=0 tray-open=0 io-status=ok [not inserted]
floppy0: removable=1 locked=0 tray-open=0 [not inserted]
sd0: removable=1 locked=0 tray-open=0 [not inserted]
(qemu) ? commit 
commit device|all -- commit changes to the disk images (if -snapshot is used) or backing files
(qemu) commit drive-virtio0-0-0

Expected result:
should fail to commit to a read-only disk with an error message prompts mentioned that backing image is read-only.
Comment 2 Sibiao Luo 2013-01-11 08:32:52 UTC 
(In reply to comment #1)
> 
> Expected result:
> should fail to commit to a read-only disk with an error message prompts
> mentioned that backing image is read-only.

check the data disk size and modify time in host, but there is no any changes before and after commit.
- before step 1:
# ls -l /home/my-data-disk.qcow2
-rw-r--r--. 1 root root 8725790720 Jan 10 11:09 /home/my-data-disk.qcow2
- after step 3:
# ls -l /home/my-data-disk.qcow2
-rw-r--r--. 1 root root 8725790720 Jan 10 11:09 /home/my-data-disk.qcow2
Comment 3 Sibiao Luo 2013-01-11 09:51:00 UTC 
*** Bug 894251 has been marked as a duplicate of this bug. ***
Comment 4 Sibiao Luo 2013-01-11 09:51:20 UTC 
*** Bug 894250 has been marked as a duplicate of this bug. ***
Comment 5 Jeff Cody 2013-01-15 22:32:31 UTC 
For completeness, from BZ #856505:

In bdrv_commit(), we are (appropriately) refusing to write to the backing file (in this case, the top-level snapshot, as the active layer is a temp image).  The function bdrv_reopen() returns an error, and bdrv_commit() returns -EACCES.

However, do_commit(), which is the message handler that calls bdrv_commit(), only checks for -EBUSY when it comes to returning an error message.
Comment 6 Jeff Cody 2013-01-18 19:40:03 UTC 
Patch submitted upstream:
https://lists.gnu.org/archive/html/qemu-devel/2013-01/msg03456.html
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