BTRFS cache problem

BTRFS cache problem

[Swâmi Petaramesh]

Hi,

My BTRFS is mounted with space_cache,inode_cache , and I now get at boot
time the following message :

“btrfs: free space inode generation (0) did not match free space cache
generation (189086)”

Starting once with "clear_cache" doesn't seem to be able to fix the
issue... Any clue ?

TIA.

-- 
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.

Re: BTRFS cache problem

[Bart Noordervliet]

Hi Swami,

which kernel version are you running?

Regards,

Bart

On Sat, Nov 10, 2012 at 11:14 PM, Swâmi Petaramesh <swami@petaramesh.org> wrote:
> Hi,
>
> My BTRFS is mounted with space_cache,inode_cache , and I now get at boot
> time the following message :
>
> “btrfs: free space inode generation (0) did not match free space cache
> generation (189086)”
>
> Starting once with "clear_cache" doesn't seem to be able to fix the
> issue... Any clue ?
>
> TIA.
>
> --
> Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
> Ne cherchez pas : Je ne suis pas sur Facebook.
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: BTRFS cache problem

[Swâmi Petaramesh]

Le 11/11/2012 15:05, Bart Noordervliet a écrit :
> which kernel version are you running?

Hi Bart,

# uname -srv
Linux 3.5.0-18-generic #29-Ubuntu SMP Fri Oct 19 10:26:51 UTC 2012

-- 
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.

Re: BTRFS cache problem

[Swâmi Petaramesh]

Le 11/11/2012 15:21, Bart Noordervliet a écrit :
>> # uname -srv Linux 3.5.0-18-generic #29-Ubuntu SMP Fri Oct 19
>> 10:26:51 UTC 2012 
> Could you first try with either 3.6 or a recent 3.7-rc build please?
> You can easily add them to Ubuntu by using their kernel ppa:
> http://kernel.ubuntu.com/~kernel-ppa/mainline/

I previously had bad times running "future" mainline kernels when
returning to previous "usual" kernels, as BTRFS didn't seem to like this
back-and-forth kernel play...

I'm not going to take risks with this machine, which is my main laptop
which I badly need to be in working order tomorrow morning (and #me
having slept at night... ;-)

-- 
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.

Re: BTRFS cache problem

[Bart Noordervliet]

On Sun, Nov 11, 2012 at 3:26 PM, Swâmi Petaramesh <swami@petaramesh.org> wrote:
> I'm not going to take risks with this machine, which is my main laptop
> which I badly need to be in working order tomorrow morning (and #me
> having slept at night... ;-)

Without running different kernels, I don't think we can work with you
to figure out the cause of the problem, unless this is a known problem
(it isn't to me). You didn't mention whether the filesystem actually
mounts properly or not, but if it does then I don't think you'll have
problems other than perhaps diminished performance.

May I also suggest that you maybe shouldn't be running an experimental
filesystem on a laptop that you can't go without?

Re: BTRFS cache problem

[Hugo Mills]

[-- Attachment #1: Type: text/plain, Size: 1350 bytes --]

On Sat, Nov 10, 2012 at 11:14:46PM +0100, Swâmi Petaramesh wrote:
> Hi,
> 
> My BTRFS is mounted with space_cache,inode_cache , and I now get at boot
> time the following message :
> 
> “btrfs: free space inode generation (0) did not match free space cache
> generation (189086)”
> 
> Starting once with "clear_cache" doesn't seem to be able to fix the
> issue... Any clue ?

   You only need to mount with space_cache once, and after that it's
"sticky". What's probably happening is that you're mounting with
space_cache, which rebuilds the cache. Then, if you reboot before it's
finished rebuilding the cache, the cache isn't complete, and (I think)
it causes the above message -- which is harmless. The same applies to
the inode cache options.

   Try mounting with clear_cache *once*, then remounting with
space_cache,inode_cache *once*, and waiting for it to finish
rebuilding the cache. Finally, remove all mention of the caches from
your fstab and kernel command line before you next mount the FS.

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
  PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
         --- Great oxymorons of the world, no. 8: The Latest ---         
                          In Proven Technology                           

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 828 bytes --]

Re: BTRFS cache problem

[Swâmi Petaramesh]

Le 11/11/2012 16:20, Hugo Mills a écrit :
> You only need to mount with space_cache once, and after that it's
> "sticky". What's probably happening is that you're mounting with
> space_cache, which rebuilds the cache. Then, if you reboot before it's
> finished rebuilding the cache, the cache isn't complete, and (I think)
> it causes the above message -- which is harmless. The same applies to
> the inode cache options. Try mounting with clear_cache *once*, then
> remounting with space_cache,inode_cache *once*, and waiting for it to
> finish rebuilding the cache. Finally, remove all mention of the caches
> from your fstab and kernel command line before you next mount the FS.
> Hugo. 

Thanks very much Hugo, I'll give this a try. Should I assume that the
cache clearing / building is complete as soon as the disk is idle ?

-- 
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.

Re: BTRFS cache problem

[Hugo Mills]

[-- Attachment #1: Type: text/plain, Size: 1378 bytes --]

On Sun, Nov 11, 2012 at 04:28:54PM +0100, Swâmi Petaramesh wrote:
> Le 11/11/2012 16:20, Hugo Mills a écrit :
> > You only need to mount with space_cache once, and after that it's
> > "sticky". What's probably happening is that you're mounting with
> > space_cache, which rebuilds the cache. Then, if you reboot before it's
> > finished rebuilding the cache, the cache isn't complete, and (I think)
> > it causes the above message -- which is harmless. The same applies to
> > the inode cache options. Try mounting with clear_cache *once*, then
> > remounting with space_cache,inode_cache *once*, and waiting for it to
> > finish rebuilding the cache. Finally, remove all mention of the caches
> > from your fstab and kernel command line before you next mount the FS.
> > Hugo. 
> 
> Thanks very much Hugo, I'll give this a try. Should I assume that the
> cache clearing / building is complete as soon as the disk is idle ?

   I'm not sure. Probably. There is probably (I haven't checked
recently) a kernel process which does the rebuilding.

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
  PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
         --- Great oxymorons of the world, no. 8: The Latest ---         
                          In Proven Technology                           

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 828 bytes --]

Re: BTRFS cache problem

[Swâmi Petaramesh]

Le 11/11/2012 16:13, Bart Noordervliet a écrit :
> May I also suggest that you maybe shouldn't be running an experimental
> filesystem on a laptop that you can't go without?

I might well be retired before BTRFS is no more "experimental", but I
need its features now...

Otherwise I could go with “ZFS on Linux” that has proven fairly
excellent and much faster and more stable than BTRFS on the machine on
which I've been using it for ~2 years...

I chosed to go for BTRFS on this machine because it's officially part of
the Linux kernel and I would expect it to improve (quickly) over time...

But for now I have to admit that I regret my choice performance wise
(which is terrible...) and stability wise (Already 2 reinstalls with
complete format, if there's a next one, the next one will be ZFS...)

Kind regards.

-- 
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.

Re: BTRFS cache problem

[Swâmi Petaramesh]

Le 11/11/2012 16:20, Hugo Mills a écrit :
> Try mounting with clear_cache *once*, then remounting with
> space_cache,inode_cache *once*, and waiting for it to finish
> rebuilding the cache. Finally, remove all mention of the caches from
> your fstab and kernel command line before you next mount the FS.
Unfortunately, same issue after applying your suggestions...

[  752.943532] btrfs: free space inode generation (0) did not match free
space cache generation (203710)


-- 
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.