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SubjectRe: Confirmation; Severe ext2fs Corruption in 2.1.98
On Fri, 29 May 1998, Chris Wedgwood wrote:

#> In short; this is a kernel bug. It is NOT pretty. I don't know WHAT causes
#> it. I can't even reproduce it. Which makes fixing it a LOT harder.
#Every two weeks or so there is a posting about ext2fs corruption.

Heh.

#Most of them turn out to be hardware related or maybe the buffer-cache or
#some kernel memory gets trashed by buggy driver or something....

After some careful thought, I believe I've got a theory as to the bug.

It's somewhere in the buffer handling.

[root@eiterra /quake]# free
total used free shared buffers cached
Mem: 62704 60676 2028 20828 4488 24696
-/+ buffers/cache: 31492 31212
Swap: 34236 1056 33180

Now, think about this. Here's the file...

-rw-r--r-- 1 root root 3968254 May 6 23:31
Robert_Pohl-Master_Of_Evil.mp3

It was being moved from /home/irc (hdb2) to /mp3/dance (sda1). As you can
see, this file would most likely be buffered in it's entirety. Now
/home/irc is totally destroyed. Only the directories themselves remain
undamaged. Every file in every subdirectory is trashed. Yet sda1 has
absolutely NO damage. I pored over every subdirectory on the drive in
search of a damaged file or directory. NOTHING. So it's happening
somewhere along the line where the file is removed from hdb2. The reboot
happens, presumably due to something inside the file, and *WHAM*. The
original remains, and all files and subdirectories of the directory that
the file was in are destroyed. Leaving the buffer handling as the primary
suspect. If anybody can reproduce this, I'd love to know about it, because
I tried three times today, with no success.

-Phil R. Jaenke (kernel@nls.net / prj@nls.net)
TheGuyInCharge(tm), Ketyra Designs - We get paid to break stuff :)
Linux pkrea.ketyra.INT 2.0.33 #15 Sat Apr 18 00:40:21 EDT 1998 i586
Linux eiterra.nls.net 2.1.98 #15 Fri May 1 18:21:00 EDT 1998 i586
- Linus says for 'brave people only.' I say 'keep a backup.' - :)
! I reserve the right to bill spammers for my time and disk space !


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