On Thu, Dec 09, 2021 at 05:54:15PM +0800, Liang Cong wrote:
Dear developers：
I found one issue during regular test and I could not confirm whether it is a libvirt|qemu issue or it is a nfs client issue or it is not an issue, so could you help to check it? Below is the issue reproduce steps:
1.there is a nfs server with exports file like: /nfs *(async,rw,no_root_squash) 2. host machine soft mount nfs: mount nfs_server_ip:/nfs /var/lib/libvirt/images/nfs -o v4,soft 3. start a guest vm with disk tag xml like below: <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/var/lib/libvirt/images/nfs/RHEL-8.6.0-20211102.1-x86_64.qcow2' index='1'/> <backingStore/> <target dev='vda' bus='virtio'/> <alias name='virtio-disk0'/> </disk> 4.Start the vm and during the guest vm boot, apply the iptables rule to drop the nfs connection to nfs server iptables -A OUTPUT -d nfs_server_ip -p tcp --dport 2049 -j DROP 5. Wait until the error log appear in /var/log/message kernel: nfs: server nfs_server_ip not responding, timed out 6. delete the iptables rule to retain the connection to nfs server iptables -D OUTPUT -d nfs_server_ip -p tcp --dport 2049 -j DROP 7. check the guest vm, found the boot process with error and can not recover. rror: ../../grub-core/disk/i386/pc/biosdisk.c:546:failure reading sector
0x7ab8 from `hd0'.
error: ../../grub-core/disk/i386/pc/biosdisk.c:546:failure reading sector
0x9190 from `hd0'.
error: ../../grub-core/disk/i386/pc/biosdisk.c:546:failure reading sector
So this shows that I/O errors have been sent from the host to the guest. This means two things: - The host has reported I/O errors to QEMU - QEMU is confjigured to reporte I/O errors to the guest (rerror/werror attributes for disk config) I expect the first point there is a result of you using 'soft' for the NFS mount - try it again with 'hard'. The alternative for 'rerror/werror' is to pause the guest, allowing the host problem to be solved whereupon you unpause the guest. Overall this behaviour just looks like a result of your config choices. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|