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-   -   dm-thin: commit metadata bug (http://www.linux-archive.org/device-mapper-development/560861-dm-thin-commit-metadata-bug.html)

Mikulas Patocka 08-05-2011 12:59 PM

dm-thin: commit metadata bug
 
There is a bug in committing metadata --- you can't commit metadata if
there is any copying or zeroing in flight. The problem is that in this
case, the block you are copying to is already allocated, but it is not
linked anywhere in the metadata. So it creates lost blocks in case of
crash.

Mikulas

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Joe Thornber 08-05-2011 01:13 PM

dm-thin: commit metadata bug
 
On Fri, Aug 05, 2011 at 08:59:09AM -0400, Mikulas Patocka wrote:
> There is a bug in committing metadata --- you can't commit metadata if
> there is any copying or zeroing in flight. The problem is that in this
> case, the block you are copying to is already allocated, but it is not
> linked anywhere in the metadata. So it creates lost blocks in case of
> crash.

Yes, well known and documented. We take this hit, fsck will repair.

- Joe

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