Re: [Qemu-devel] [Bug 1254940] [NEW] qemu-KVM guest OS occurs many ext3-fs errors after multiple forced shutdown

[Stefan Hajnoczi]

On Tue, Nov 26, 2013 at 01:59:41AM -0000, benjamin_zb wrote:
> I met some filesysterm errors in a sles guest on KVM. My system environment 
> is:
> HOST:
>    suse 10, the kernel version is 2.6.32.43
>    Qemu-KVM 1.2
>    Libvirt 1.0
> guest OS:
>    suse 10, the kernel version is 2.6.32.43
> VMs use a qcow2 disk.
> 
> Description of problem:
> I have 20+ VMs with qcow2 disk, these VMs have been forced to shut down by
> "virsh destroy" many times during and after VM installation.
> When these vm reboot,dmesg show a ext3-fs mount error occurred on /usr/local
> partion /dev/vda3:
>     EXT3-fs warning: mounting fs with errors, running e2fsck is recommendedand
> when I wrote into partion /dev/vda3,some errors occurred in dmesg:
> 1.error (device vda3): ext3_free_blocks: Freeing blocks not in datazone - 
> block
> = 1869619311, count = 1error (device vda3): ext3_free_blocks_sb: bit already
> cleared for block 2178152error (device vda3): ext3_readdir: bad entry in
> directory #1083501:
> 2.[347470.661893] attempt to access beyond end of device[347470.661896] vda3:
> rw=0, want=6870892952, limit=41945715[347470.661897] EXT3-fs error (device
> vda3): ext3_free_branches: Read failure, inode=1083508, block=858861618
> 3.EXT3-fs error (device vda3): ext3_new_block: block(4295028581) >= blocks
> count(-1) - block_group = 1, es == ffff88021b6c7400
> 
> I suspect this fs-error is caused by multiple forced shutdown, but I can't
> reproduce this bug now.
> 
> Could anyone has an idea or suggestion to help me?

What are the mount options for this ext3 file system?

In particular, make sure the barrier=1 option is set.

>From linux/Documentation/filesystems/ext3.txt:

  Write barriers enforce proper on-disk ordering of journal commits,
  making volatile disk write caches safe to use, at some performance
  penalty.

Stefan