This bug was fixed in the package qemu-kvm - 1.2.0+noroms- 0ubuntu2.12.10.1
--------------- qemu-kvm (1.2.0+noroms-0ubuntu2.12.10.1) quantal-proposed; urgency=low [ Serge Hallyn ] * debian/qemu-kvm.postinst: use udevadm trigger to change /dev/kvm perms as recommended by Steve Langasek (LP: #1057024) * apply debian/patches/nbd-fixes-to-read-only-handling.patch from upstream to make read-write mount after read-only mount work. (LP: #1077838) * make qemu-kvm depend on udev (LP: #1080912) [ Robert Collins ] * Fix upstart job to succeed if ksm settings can't be altered in the same way other settings are handled. (LP: #1078530) -- Serge Hallyn <serge.hal...@ubuntu.com> Mon, 19 Nov 2012 09:15:42 -0600 ** Changed in: qemu-kvm (Ubuntu Quantal) Status: Fix Committed => Fix Released ** Changed in: qemu-kvm (Ubuntu Precise) Status: Fix Committed => Fix Released -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1077838 Title: qemu-nbd -r -c taints device for subsequent usage, even after -d Status in QEMU: In Progress Status in “qemu-kvm” package in Ubuntu: Fix Released Status in “qemu-kvm” source package in Precise: Fix Released Status in “qemu-kvm” source package in Quantal: Fix Released Bug description: Something about qemu-nbd -r -c /dev/nbd0 someimg leaves cruft behind - subsequent connections get marked readonly. This is on quantal, haven't checked precise or raring. To demonstrate: # use one image qemu-img create -f qcow2 /tmp/1.qcow2 100M sudo qemu-nbd -c /dev/nbd2 /tmp/1.qcow2 sudo mkfs -t ext4 /dev/nbd2 sudo qemu-nbd -d /dev/nbd2 # use a second one on the same nbd device, shows that reuse works: qemu-img create -f qcow2 /tmp/2.qcow2 100M sudo qemu-nbd -c /dev/nbd2 /tmp/2.qcow2 sudo mkfs -t ext4 /dev/nbd2 sudo qemu-nbd -d /dev/nbd2 # connect an image in read only mode sudo qemu-nbd -r -c /dev/nbd2 /tmp/2.qcow2 sudo dumpe2fs /dev/nbd2 | head -n 3 sudo qemu-nbd -d /dev/nbd2 # now try to reuse in read-write mode again: qemu-img create -f qcow2 /tmp/3.qcow2 100M sudo qemu-nbd -c /dev/nbd2 /tmp/3.qcow2 sudo mkfs -t ext4 /dev/nbd2 # here it goes boom: mke2fs 1.42.5 (29-Jul-2012) /dev/nbd2: Operation not permitted while setting up superblock # still need to cleanup sudo qemu-nbd -d /dev/nbd2 =============================== SRU Justification: 1. Impact: mounting an nbd device as read-write after doing so read-only will cause the mount to erroneously (and quietly) be read-only. 2. Development fix: have qemu-nbd set the device to read-write when asked, rather than only setting read-only. 3. Stable fix: same as development fix 4. Test case: See above 5. Regression potential: The patch is localized to the handling of read-only flag in qemu-nbd, so any regression should not affect anything else. =============================== To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1077838/+subscriptions