[linux-lvm] mounting ext3 snapshot occasionaly fails

[linux-lvm] mounting ext3 snapshot occasionaly fails

[Tomaz Beltram]

Hi,

I have similar problems as described in this mailing list some months ago, 
regarding mounting snapshots of journaled file systems.

Mounting the snapshot fails and dmesg shows:
EXT3-fs: INFO: recovery required on readonly filesystem.
EXT3-fs: write access unavailable, cannot proceed.

I have observed that the failure is more frequent with longer delays between 
snapshot creation and mount time.

The problem was solved with the VFS-lock patch for 2.4.18 kernel. But I am 
using LVM 1.0.5 and 2.4.19-SuSE kernel (64GB-SMP). As I understand, it 
should already have the VFS-lock patch applied. If not, where can I find 
one?

Thanks in advance for your help.
Tomaz

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Re: [linux-lvm] mounting ext3 snapshot occasionaly fails

[Patrick Caulfield]

On Tue, Dec 03, 2002 at 12:35:09PM +0000, Tomaz Beltram wrote:
> Hi,
> 
> I have similar problems as described in this mailing list some months ago, 
> regarding mounting snapshots of journaled file systems.
> 
> Mounting the snapshot fails and dmesg shows:
> EXT3-fs: INFO: recovery required on readonly filesystem.
> EXT3-fs: write access unavailable, cannot proceed.
> 
> I have observed that the failure is more frequent with longer delays 
> between snapshot creation and mount time.
> 
> The problem was solved with the VFS-lock patch for 2.4.18 kernel. But I am 
> using LVM 1.0.5 and 2.4.19-SuSE kernel (64GB-SMP). As I understand, it 
> should already have the VFS-lock patch applied. If not, where can I find 
> one?

I don't know whether the SuSE kernel has the VFS lock patch applied or not - if
not then one for 2.4.19 is available in the LVM 1.0.6 source package.

The patch is agains the Linus kernel so whether it will apply to the SuSE
kernel is something you'll have to find out for yourself I'm afraid !

patrick

Re: [linux-lvm] mounting ext3 snapshot occasionaly fails

[Chris Mason]

On Tue, 2002-12-03 at 07:44, Patrick Caulfield wrote:
> On Tue, Dec 03, 2002 at 12:35:09PM +0000, Tomaz Beltram wrote:
> > Hi,
> > 
> > I have similar problems as described in this mailing list some months ago, 
> > regarding mounting snapshots of journaled file systems.
> > 
> > Mounting the snapshot fails and dmesg shows:
> > EXT3-fs: INFO: recovery required on readonly filesystem.
> > EXT3-fs: write access unavailable, cannot proceed.
> > 
> > I have observed that the failure is more frequent with longer delays 
> > between snapshot creation and mount time.
> > 
> > The problem was solved with the VFS-lock patch for 2.4.18 kernel. But I am 
> > using LVM 1.0.5 and 2.4.19-SuSE kernel (64GB-SMP). As I understand, it 
> > should already have the VFS-lock patch applied. If not, where can I find 
> > one?
> 
> I don't know whether the SuSE kernel has the VFS lock patch applied or not - if
> not then one for 2.4.19 is available in the LVM 1.0.6 source package.
> 
> The patch is agains the Linus kernel so whether it will apply to the SuSE
> kernel is something you'll have to find out for yourself I'm afraid !

The suse kernel already has the patch, so there might be a timing
problem in the ext3 support.

-chris

[linux-lvm] mounting ext3 snapshot occasionaly fails

[Tomaz Beltram]

>I don't know whether the SuSE kernel has the VFS lock patch applied or >not 
>- if
>not then one for 2.4.19 is available in the LVM 1.0.6 source package.

I found the linux-2.4.19-VFS-lock.patch in the LVM 1.0.5 src package. 
However, it results to me that it is already included. Patch says:
Reversed (or previously applied) patch detected!

Beside that, I can see the new symbols that come with the patch in my 
running kernel:
# cat /proc/ksyms | grep lockfs
c014cf90 fsync_dev_lockfs
c0151680 unlockfs

I was able to reproduce this with following steps:
VG=vg1
lvcreate -L 100M -n lv1 $VG
mke2fs -j /dev/$VG/lv1
mkdir /mnt/fs1
mount -t ext3 /dev/$VG/lv1 /mnt/fs1
lvcreate -L 10M -n lv1_snap -s /dev/$VG/lv1
mkdir /mnt/fs1_snap
mkdir /mnt/fs1/dir
sleep 60
mount -t ext3 -r /dev/$VG/lv1_snap /mnt/fs1_snap

Please note that the change to the original file system is made *after* the 
snapshot is created, so this could be different problem.

thanks again
Tomaz

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