Dne 4.2.2014 09:55, Christian Hesse napsal(a):
Christian Hesse <list@eworm.de> on Thu, 2014/01/23 14:27:
Hello everybody,
looks like lvm2 2.02.105 breaks snapshots. This is my block device tree:
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 477G 0 disk
|-sda1 8:1 0 767M 0 part
| `-vg0-boot 254:0 0 64M 0 lvm /boot
|-sda2 8:2 0 444,2G 0 part
| `-cvg 254:3 0 444,2G 0 crypt
| |-cvg-root 254:4 0 40G 0 lvm /
| |-cvg-swap 254:5 0 4G 0 lvm [SWAP]
| |-cvg-log 254:6 0 1G 0 lvm /var/log
| `-cvg-home 254:8 0 320G 0 lvm /home
|-sda3 8:3 0 32G 0 part
`-sda128 259:0 0 1M 0 part
Creating a snapshot succeeds, but it is broken and can not be mounted:
# lvcreate -s -pr -l50%free -n snap-home cvg/home
Logical volume "snap-home" created
# mount /dev/cvg/snap-home /mnt/tmp
mount: /dev/mapper/cvg-snap--home is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on
/dev/mapper/cvg-snap--home, missing codepage or helper program, or other
error
Syslog has a lot of these messages:
[ 4823.002220] EXT4-fs (dm-7): ext4_check_descriptors: Checksum for group
256 failed (43470!=57954)
Downgrading to lvm2 2.02.104 fixes the problem:
# lvcreate -s -pr -l50%free -n snap-home
cvg/home Logical volume "snap-home" created
# mount /dev/cvg/snap-home /mnt/tmp
mount: /dev/mapper/cvg-snap--home is write-protected, mounting read-only
This is an Arch Linux system with Linux 3.12.8.
Hello everybody,
did anybody notice my mail? This is a real regression for me and I would like
to get this sorted. I will help with whatever is needed to find the problem.
Ok - could you test this:
Create an lv - ('lvcreate -Lsmallsize vg'
mount this lv somewhere
modify this filesystem (via dd)
'fsfreeze --freeze mountpoint'
now - copy whole frozen device somewhere (via dd)
'fsfreeze --unfreeze mountpoint'
umount mountpoint
losetup -r /dev/loop_free_number frozen_copy_of_device
and now - try to mount your read-only loop device copy.
Does it work for you ?
I've been testing this - and it seem fsfreeze API in kernel is not working
properly and you need to reply journal.
Then try to repeat the same with 3.10 kernel and 3.4 kernel.
So far I'm not convinced lvm2 version has anything to do with this problem
For 3.10 ext4 seems to work, but xfs is broken.
Regards
Zdenek
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