Re: NilFS cleanerd bugreport

[Ryusuke Konishi <ryusuke-sG5X7nlA6pw@public.gmane.org>]

Hi Reinoud,
On Wed, 28 Jan 2009 21:52:23 +0100, Reinoud Zandijk wrote:
> Dear folks, dear Ryusuke,
> 
> I've found a bug in the cleanerd/nilfs interaction that might give rise to the
> various problems we've seen recently with the cleanerd. It comes down to the
> wrong counting of the number of dirty segments and the wrong counting of the
> number of checkpoints.
> 
> I created this disc using the NiLFS version 2.05 with 2.06 userland (AFAIK)
> with mkfs.nilfs and created a sparse file on it with my sparse file generator
> I created for UDF testing. It dismounted fine giving a nilfs_dump
> `vnd0e-dump-3'. When i remounted it again, the cleanerd started after a while
> and after unmounting it gives `vnd03-dump-3-cleanerd'. A diff shows:
<snip>
> And the su and cp files give:
> 
> @@ -30743,34 +31480,34 @@
>  Reading file `SU.out` for 1 blocks (4 Kb)
>  
>  	SU file dump
> -		nclean       491
> -		ndirty       8
> +		nclean       496
> +		ndirty       21474836483
>  		last alloced 7
>  
>  		Segment 0
> -		Last modified Sun Jan 25 17:05:28 2009
> -		Containing nblks 2047
> -		Flags            0x2<DIRTY>
> +		Last modified Thu Jan  1 01:00:00 1970
> +		Containing nblks 0
> +		Flags            0x0
> 
> ......
> 
> @@ -30789,136 +31526,72 @@
>  
>  Reading file `CP.out` for 1 blocks (4 Kb)
>  	CP file dump
> -		Number of checkpoints 8
> +		Number of checkpoints 8589934596
>  		Number of snapshots   0
>  
>  		Checkpoint number    1
> -		Flags                0x0
> +		Flags                0x2<INVALID>
>  		Checkpoints in block 0
>  		Created at Sun Jan 25 17:05:10 2009
>  		Blocks incremented   11
>  		Inodes count         3
>  		Blocks count (red.)  9
> 
> ny idea as to if and why this can happen?

looks underflow or collision of updates.

> Has it been fixed in the meantime?

Not yet, I think.

> or could this be a clue as to the wierd behaviour seen by others including the
> corruption?

I don't know.  As I remember, the cleanerd does not depend on these
values, but it may be indirectly-induced.

Anyway, thanks for reporting this issue.
I'll review the cpfile and sufile again.

Regards,
Ryusuke Konishi