[linux-lvm] mounting reiserfs snapshot fails

[linux-lvm] mounting reiserfs snapshot fails

[Ed Tomlinson]

Hi,

Using debian sid, 2.4.3-ac5, lvm 0.91 beta7, with the vfs locking
patch applied I get:

oscar# mount /dev/lv/snap /snap -t reiserfs -oro
mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
       or too many mounted file systems

When trying to mount the snap shot.  It was created with: 
lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
without problems

Ideas?
Ed Tomlinson

Re: [linux-lvm] mounting reiserfs snapshot fails

[Chris Mason]

On Friday, April 13, 2001 01:29:58 PM -0400 Ed Tomlinson <tomlins@cam.org>
wrote:

> Hi,
> 
> Using debian sid, 2.4.3-ac5, lvm 0.91 beta7, with the vfs locking
> patch applied I get:
> 
> oscar# mount /dev/lv/snap /snap -t reiserfs -oro
> mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
>        or too many mounted file systems

BTW, you can drop the -o ro, LVM sets the snapshot device readonly, so VFS
forces a readonly mount for you.

> 
> When trying to mount the snap shot.  It was created with: 
> lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
> without problems

I doubt it, but was /dev/lv/root a freshly created reiserfs disk?

What does dumpreiserfs tell you about /dev/lv/snap and /dev/lv/root tell
you?

-chris

Re: [linux-lvm] mounting reiserfs snapshot fails

[Ed Tomlinson]

On Friday 13 April 2001 16:36, Chris Mason wrote:
> On Friday, April 13, 2001 01:29:58 PM -0400 Ed Tomlinson <tomlins@cam.org>
>
> wrote:
> > Hi,
> >
> > Using debian sid, 2.4.3-ac5, lvm 0.91 beta7, with the vfs locking
> > patch applied I get:
> >
> > oscar# mount /dev/lv/snap /snap -t reiserfs -oro
> > mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
> >        or too many mounted file systems
>
> BTW, you can drop the -o ro, LVM sets the snapshot device readonly, so VFS
> forces a readonly mount for you.
>
> > When trying to mount the snap shot.  It was created with:
> > lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
> > without problems
>
> I doubt it, but was /dev/lv/root a freshly created reiserfs disk?
>
> What does dumpreiserfs tell you about /dev/lv/snap and /dev/lv/root tell
> you?

oscar# lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
lvcreate -- WARNING: the snapshot will be automatically disabled once it gets full
lvcreate -- INFO: using default snapshot chunk size of 64 KB for "/dev/lv/snap"
lvcreate -- doing automatic backup of "lv"
lvcreate -- logical volume "/dev/lv/snap" successfully created
 
oscar# mount -t reiserfs /dev/lv/snap /snap
mount: block device /dev/lv/snap is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
       or too many mounted file systems

oscar# dumpreiserfs /dev/lv/snap
dumpe2fs 1.19, 13-Jul-2000 for EXT2 FS 0.5b, 95/08/09
dumpreiserfs: Bad magic number in super-block while trying to open /dev/lv/snap
Couldn't find valid filesystem superblock.

oscar# dumpreiserfs /dev/lv/root
dumpe2fs 1.19, 13-Jul-2000 for EXT2 FS 0.5b, 95/08/09
dumpreiserfs: Bad magic number in super-block while trying to open /dev/lv/root
Couldn't find valid filesystem superblock.oscar# debugreiserfs /dev/lv/snap
 
<-------------debugreiserfs, 2001------------->
reiserfsprogs 3.x.0j
reiserfs_open: neither new nor old reiserfs format found on /dev/lv/snap
print_block: buffer is NULL
oscar# debugreiserfs /dev/lv/root
 
<-------------debugreiserfs, 2001------------->
reiserfsprogs 3.x.0j
Super block of format 3.6 found on the 0x3 in block 16
Block count 3670016
Blocksize 4096
Free blocks 1241068
Busy blocks (skipped 16, bitmaps - 112, journal blocks - 8193
1 super blocks, 2420626 data blocks
Root block 40201
Journal block (first) 18
Journal dev 0
Journal orig size 8192
Filesystem state ERROR
Tree height 5
Hash function used to sort names: "r5"
Objectid map size 304, max 972
Version 2
oscar#                               = ?

Ed

Re: [linux-lvm] mounting reiserfs snapshot fails

[Andreas Dilger]

Ed Tomlinson writes:
> Using debian sid, 2.4.3-ac5, lvm 0.91 beta7, with the vfs locking
> patch applied I get:
> 
> oscar# mount /dev/lv/snap /snap -t reiserfs -oro
> mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
>        or too many mounted file systems
> 
> When trying to mount the snap shot.  It was created with: 
> lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
> without problems

Are you sure that the VFS patch is applied, and that the LVM and
reiserfs code was compiled with "enable VFS patch" (whatever it is
called) enabled?  That has been a source of problems in the past.
The patch was applied, but you also need to enable it for both the
reiserfs and LVM code.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert

Re: [reiserfs-list] Re: [linux-lvm] mounting reiserfs snapshot fails

[Chris Mason]

On Friday, April 13, 2001 06:23:28 PM -0600 Andreas Dilger
<adilger@turbolinux.com> wrote:

> Ed Tomlinson writes:
>> Using debian sid, 2.4.3-ac5, lvm 0.91 beta7, with the vfs locking
>> patch applied I get:
>> 
>> oscar# mount /dev/lv/snap /snap -t reiserfs -oro
>> mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
>>        or too many mounted file systems
>> 
>> When trying to mount the snap shot.  It was created with: 
>> lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
>> without problems
> 
> Are you sure that the VFS patch is applied, and that the LVM and
> reiserfs code was compiled with "enable VFS patch" (whatever it is
> called) enabled?  That has been a source of problems in the past.
> The patch was applied, but you also need to enable it for both the
> reiserfs and LVM code.

That would be a different error, reiserfs would complain that it found a
filesystem, but was unable to mount it because it needed replay and the
device was readonly.  In this case, the snapshot is not a valid FS at all,
even though the source looks fine.

I'll upgrade to the latest LVM and try to reproduce...

-chris

Re: [reiserfs-list] Re: [linux-lvm] mounting reiserfs snapshot fails

[Ed Tomlinson]

On Friday 13 April 2001 20:53, Chris Mason wrote:

> I'll upgrade to the latest LVM and try to reproduce...

This is still happening with ac7, which has the 2.4.4-pre3 fixes merged.

Ed

[linux-lvm] Re: [reiserfs-list] mounting reiserfs snapshot fails

[Chris Mason]

On Friday, April 13, 2001 01:29:58 PM -0400 Ed Tomlinson <tomlins@cam.org>
wrote:

> Hi,
> 
> Using debian sid, 2.4.3-ac5, lvm 0.91 beta7, with the vfs locking
> patch applied I get:
> 
> oscar# mount /dev/lv/snap /snap -t reiserfs -oro
> mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
>        or too many mounted file systems
> 
> When trying to mount the snap shot.  It was created with: 
> lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
> without problems

I'm not sure what you're doing that I wasn't, but I've tried a bunch of
times to reproduce this over the last few weeks.  Tonight I finally did ;-)

The bug is that reiserfs needs to try harder to wait for the current
transaction to end.  A slight change in the semantics there didn't get
carried into the reiserfs write_super_lockfs call (reiserfs_block_writes
used to be enough on its own).  

But, it only hits when LVM can create the snapshot faster than the next
reiserfs writer can commit the transaction, which doesn't happen often for
me.

Anyway, here's a patch (VFS locking patch for 2.4.4 will follow in a sec).

-chris

diff -Nru a/fs/reiserfs/super.c b/fs/reiserfs/super.c
--- a/fs/reiserfs/super.c	Sun Apr 29 20:44:38 2001
+++ b/fs/reiserfs/super.c	Sun Apr 29 20:44:38 2001
@@ -80,7 +80,7 @@
     reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
     journal_mark_dirty(&th, s, SB_BUFFER_WITH_SB (s));
     reiserfs_block_writes(&th) ;
-    journal_end(&th, s, 1) ;
+    journal_end_sync(&th, s, 1) ;
   }
   s->s_dirt = dirty;
   unlock_kernel() ;

[linux-lvm] Re: [reiserfs-list] mounting reiserfs snapshot fails

[Ed Tomlinson]

On Sunday 29 April 2001 21:48, Chris Mason wrote:
> On Friday, April 13, 2001 01:29:58 PM -0400 Ed Tomlinson <tomlins@cam.org>
>
> wrote:
> > Hi,
> >
> > Using debian sid, 2.4.3-ac5, lvm 0.91 beta7, with the vfs locking
> > patch applied I get:
> >
> > oscar# mount /dev/lv/snap /snap -t reiserfs -oro
> > mount: wrong fs type, bad option, bad superblock on /dev/lv/snap,
> >        or too many mounted file systems
> >
> > When trying to mount the snap shot.  It was created with:
> > lvcreate -L 1G -s -n snap /dev/lv/root /dev/hdg1
> > without problems
>
> I'm not sure what you're doing that I wasn't, but I've tried a bunch of
> times to reproduce this over the last few weeks.  Tonight I finally did ;-)
>
> The bug is that reiserfs needs to try harder to wait for the current
> transaction to end.  A slight change in the semantics there didn't get
> carried into the reiserfs write_super_lockfs call (reiserfs_block_writes
> used to be enough on its own).
>
> But, it only hits when LVM can create the snapshot faster than the next
> reiserfs writer can commit the transaction, which doesn't happen often for
> me.
>
> Anyway, here's a patch (VFS locking patch for 2.4.4 will follow in a sec).

Chris,

This is not fixing the problem here.  What else do you need to figure this
one out?  I did verify that I built from souce with both the fix VFS locking
the the reiserfs fix applied.  Symptoms remain the same, debugreiserfs is 
still finding a null block where it expects the sb.

Ed

[linux-lvm] Re: [reiserfs-list] mounting reiserfs snapshot fails

[Ed Tomlinson]

On Monday 30 April 2001 00:23, Ed Tomlinson wrote:

> > The bug is that reiserfs needs to try harder to wait for the current
> > transaction to end.  A slight change in the semantics there didn't get
> > carried into the reiserfs write_super_lockfs call (reiserfs_block_writes
> > used to be enough on its own).
> >
> > But, it only hits when LVM can create the snapshot faster than the next
> > reiserfs writer can commit the transaction, which doesn't happen often
> > for me.
>
> This is not fixing the problem here.  What else do you need to figure this
> one out?  I did verify that I built from souce with both the fix VFS
> locking the the reiserfs fix applied.  Symptoms remain the same,
> debugreiserfs is still finding a null block where it expects the sb.

Some more info.  

If I use: lvcreate -L1G -s -n snap /dev/lv/root /dev/hdg1
the snapshoot is corrupt

if I use: lvcreate -L1G -s -n snap /dev/lv/root /dev/hde1
the snapshoot works

The difference being that /dev/lv/root is on /dev/hde1.  hdg1 is basicly
empty right now.  Suspect there is still race in this process.

Ed

Re: [linux-lvm] Re: [reiserfs-list] mounting reiserfs snapshot fails

[Chris Mason]

On Monday, April 30, 2001 12:23:14 AM -0400 Ed Tomlinson <tomlins@cam.org>
wrote:

> 
> Chris,
> 
> This is not fixing the problem here.  What else do you need to figure this
> one out?  I did verify that I built from souce with both the fix VFS
> locking the the reiserfs fix applied.  Symptoms remain the same,
> debugreiserfs is  still finding a null block where it expects the sb.
> 

Sigh.  Could you please try 2.4.4aa2 + the two patches I sent?  If that
doesn't do it, I'll send along some debugging patches.

-chris