qcow2: Preventing invalid write on metadata (overlaps with refcount block); image marked as corrupt.

[Seth Arnold]

One of my VMs remounted its filesystem read-only; I discovered this in the host's /var/log/libvirt/qemu/sec-trusty-amd64.log file:

2014-05-06 19:02:39.735+0000: shutting down
2014-05-07 18:44:45.578+0000: starting up
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin QEMU_AUDIO_DRV=none /usr/bin/kvm-spice -name sec-trusty-amd64 -S -machine pc-i440fx-trusty,accel=kvm,usb=off -m 1024 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 43a47011-0b19-6704-6a50-b41c33a3b7a4 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/sec-trusty-amd64.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/home/sarnold/Canonical/vms/sec-trusty-amd64.qcow2,if=none,id=drive-virtio-disk0,format=qcow2 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive if=none,id=drive-ide0-1-0,readonly=on,format=raw -device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -netdev tap,fd=24,id=hostnet0,vhost=on,vhostfd=26 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:89:e2:84,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -vnc 127.0.0.1:1 -device vmware-svga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
char device redirected to /dev/pts/37 (label charserial0)
qemu: terminating on signal 15 from pid 1589
2014-05-09 22:44:26.667+0000: shutting down
2014-05-09 22:44:34.245+0000: starting up
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin QEMU_AUDIO_DRV=none /usr/bin/kvm-spice -name sec-trusty-amd64 -S -machine pc-i440fx-trusty,accel=kvm,usb=off -m 1024 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 43a47011-0b19-6704-6a50-b41c33a3b7a4 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/sec-trusty-amd64.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/home/sarnold/Canonical/vms/sec-trusty-amd64.qcow2,if=none,id=drive-virtio-disk0,format=qcow2 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive if=none,id=drive-ide0-1-0,readonly=on,format=raw -device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -netdev tap,fd=24,id=hostnet0,vhost=on,vhostfd=26 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:89:e2:84,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -vnc 127.0.0.1:1 -device vmware-svga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
char device redirected to /dev/pts/37 (label charserial0)
qcow2: Preventing invalid write on metadata (overlaps with refcount block); image marked as corrupt.

Inside the guest, the tail end of dmesg output looks like:

[ 2.596345] systemd-udevd[320]: Failed to apply ACL on /dev/dri/card0: No such file or directory
[ 3.080653] init: failsafe main process (493) killed by TERM signal
[ 3.961601] init: udev-fallback-graphics main process (707) terminated with status 1
[ 5.522041] init: plymouth-upstart-bridge main process ended, respawning
[ 5.539357] init: plymouth-splash main process (982) terminated with status 1
[ 7.294746] init: plymouth-stop pre-start process (1194) terminated with status 1
[ 32.208552] random: nonblocking pool is initialized
[ 601.726533] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 45906 (offset 0 size 32768 starting block 54448)
[ 601.726546] Buffer I/O error on device vda1, logical block 54192
[ 601.726550] Buffer I/O error on device vda1, logical block 54193
[ 601.726555] Buffer I/O error on device vda1, logical block 54194
[ 601.726558] Buffer I/O error on device vda1, logical block 54195
[ 601.726560] Buffer I/O error on device vda1, logical block 54196
[ 601.726562] Buffer I/O error on device vda1, logical block 54197
[ 601.726564] Buffer I/O error on device vda1, logical block 54198
[ 601.726566] Buffer I/O error on device vda1, logical block 54199
[ 601.726611] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1011968)
[ 601.726613] Buffer I/O error on device vda1, logical block 1011712
[ 601.726616] Buffer I/O error on device vda1, logical block 1011713
[ 601.726713] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012094)
[ 601.726824] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012220)
[ 601.726896] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012346)
[ 601.726964] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012472)
[ 601.727032] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012598)
[ 601.727099] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012724)
[ 601.727172] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012850)
[ 601.727302] EXT4-fs warning (device vda1): ext4_end_bio:317: I/O error writing to inode 136339 (offset 0 size 8388608 starting block 1012976)
[ 601.729983] quiet_error: 153 callbacks suppressed
[ 601.729996] Buffer I/O error on device vda1, logical block 18108
[ 601.729999] lost page write due to I/O error on vda1
[ 601.730002] Buffer I/O error on device vda1, logical block 18109
[ 601.730004] lost page write due to I/O error on vda1
[ 601.730006] Buffer I/O error on device vda1, logical block 18110
[ 601.730008] lost page write due to I/O error on vda1
[ 601.730010] Buffer I/O error on device vda1, logical block 18111
[ 601.730012] lost page write due to I/O error on vda1
[ 601.730014] Buffer I/O error on device vda1, logical block 18112
[ 601.730015] lost page write due to I/O error on vda1
[ 601.730018] Buffer I/O error on device vda1, logical block 18113
[ 601.730019] lost page write due to I/O error on vda1
[ 601.730022] Buffer I/O error on device vda1, logical block 18114
[ 601.730023] lost page write due to I/O error on vda1
[ 601.730026] Buffer I/O error on device vda1, logical block 18115
[ 601.730027] lost page write due to I/O error on vda1
[ 601.730029] Buffer I/O error on device vda1, logical block 18116
[ 601.730031] lost page write due to I/O error on vda1
[ 601.730033] Buffer I/O error on device vda1, logical block 18117
[ 601.730035] lost page write due to I/O error on vda1
[ 601.766362] EXT4-fs error (device vda1): ext4_read_inode_bitmap:174: comm apt-get: Cannot read inode bitmap - block_group = 32, inode_bitmap = 1048592
[ 601.766507] Aborting journal on device vda1-8.
[ 601.766670] JBD2: Error -5 detected when updating journal superblock for vda1-8.
[ 601.766673] EXT4-fs (vda1): Remounting filesystem read-only
[ 601.766676] EXT4-fs error (device vda1) in ext4_evict_inode:310: IO failure
[ 601.766682] EXT4-fs (vda1): previous I/O error to superblock detected
[ 601.766781] JBD2: Detected IO errors while flushing file data on vda1-8
[ 601.767009] JBD2: Error -5 detected when updating journal superblock for vda1-8.
sarnold@sec-trusty-amd64:/tmp/qrt-test-django$

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: qemu 2.0.0+dfsg-2ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-24.47-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CurrentDesktop: Unity
Date: Wed May 14 14:30:59 2014
InstallationDate: Installed on 2012-10-18 (573 days ago)
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
SourcePackage: qemu
UpgradeStatus: Upgraded to trusty on 2014-04-12 (32 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.