Smashing EXT3 for fun and profit (or: how to loose all your data)

Joseph D. Wagner theman at
Fri May 13 19:55:55 UTC 2005

> I guess these 2 facts need fixing:
> 1) loopback devices should not pass errors over
> to their underlying filesystems.

I have a test partition setup for these circumstances.  I'll try to reproduce the read-write/read-only error spreading to an underlying file system when the loopback file system has the error.  However, I will have to double check with the file system designers.  There may be a good reason it behaves this way.

> 2) ext3 suicidally allows remounting read-write
> when parts of its data are invalid.

When you are logged in as root, it will let you whatever suicidal -- or imho stupid -- things you tell it to do.  That is not going to change.

It actually takes something serious to bring down a file system mid-stride, not just an atime update.  In other words, by the time Linux is remounting your file system as read-only, something is already fubar.  The remount as read-only is really only a stop-gap measure to prevent further damage while you save your work -- on other partitions -- and reboot.

If all you have is one honkin' / (root) partition, you may just want to change that behavior to panic.  After all, if you only have 1 partition, there's no where else to save your work.

So long as you're redoing your partitions, be sure to separate out /tmp, /var, and just to be safe /home too, so next time all you lose is the one bad partition.

Joseph D. Wagner

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