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[xfs-masters] Re: potential xfs_repair bug

To: Junfeng Yang <yjf@xxxxxxxxxxxx>, xfs-masters@xxxxxxxxxxx
Subject: [xfs-masters] Re: potential xfs_repair bug
From: Eric Sandeen <sandeen@xxxxxxx>
Date: Wed, 01 Sep 2004 23:26:19 -0500
In-reply-to: <Pine.GSO.4.44.0409011533110.24769-100000@elaine24.Stanford.EDU>
References: <Pine.GSO.4.44.0409011533110.24769-100000@elaine24.Stanford.EDU>
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How was the filesystem damaged before running xfs_repair the first time?

I'm not sure how much effort was put into protecting xfs_repair from 
crashes... I can believe that a poorly-timed crash could cause problems.

-Eric

Junfeng Yang wrote:

> Hi Eric,
> 
> do you guys intend to make xfs_repair crash-safe?
> 
> out tool flagged a warning for xfs_repair, where a prefectly correct file
> system can be messed up by xfs_repair if crash happens during xfs_repair.
> the warning can be triggered this way:
> 
> 1. run xfs_repair on a xfs image containg 1 file.  crash it right before
> the last sector is written to disk.  (in our case it is the write to
> sector 103.)
> 
> 2. run xfs_repair again on the same image.  it reports that root dir
> content is corrupted so it cleans up root dir and moves the file to
> lost+found
> 
> it appears to me that a crash during xfs_repair may wipe off all the
> entries under '/'.  does xfs_repair try to rebuild the root dir?  I'm not
> sure if this should be considered as a bug or not.  any
> conformation/clarafication is appreciated.
> 
> the fs image before step 1 can be obtainted at
> http://keeda.stanford.edu/~junfeng/orig.img.bz2
> 
> image after step 1 is at
> http://keeda.stanford.edu/~junfeng/half.img.bz2
> 
> Thanks,
> -Junfeng


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