[9fans] more fossil woes

[andrey mirtchovski <mirtchov@cpsc.ucalgary.ca>]

I never thought I'd get to that point, but here it is:

	Fossil is unable to initialize a partition with flfmt.

Here's the whole story:


This morning after succesfully checking my email from home I arrived at
school just to find that fossil has died with the familiar:

	 assert failed: b->nlock == 1
	fossil 44: suicide: sys: trap: fault read addr=0x0 pc=0x0002b6b7

It was the first crash in a long time, but unfortunately I had no way of
finding out who/what had caused it, because Plan 9 does not allow me to
examine process' activity based on utilization of a particular resource.
(Interestingly enough, when I suggested such "features" are added to the
system there was an outrage, especially from people who never use Plan 9,
telling me I'm just polluting the beautiful system :)...

I didn't give much thought to the problem and ran fossil/flchk, which
surprisingly discovered much more errors than I had thought I had. Here's
how many blocks it couldn't access anymore (I run a 3-day wide epoch
window) and had suggested that I bfree:

	mirtchov@fbsd$ cat flchk | sed '/^[^b]/d' | wc -l
	 365357
	mirtchov@fbsd$


that's 3 gigs of broken data... For comparison my entire venti archive
weights in at 1.3GB.

I examined the blocks for any obvious errors and cat them to the fossil
console, which immediately came back with the somewhat new:

	cacheLocalData: addr=7840 type got 16 exp 8: tag got 0 exp 65afd613
	fossil 94: suicide: sys: trap: fault read addr=0x0 pc=0x0002b6b7

A reboot or two later, and I had a running system that was good for checking
email. Only much later, when I needed to do some real work with Plan 9 did I
find out that /acme/bin/* was corrupted! It was showing binaries as
existing, but no file operations could be done on them. At this point I
decided that it's best to reinit fossil with the latest venti score and just
forget about it, but fossil thought differently:

	plan9# fossil/flfmt -v ff96c3967c7815e15a8a4c09196221b01a8bba3d /dev/sdD0/fossil
	cacheLocalData: addr=7841 type got 16 exp 0: tag got 0 exp 6669fe74
	fossil 90: suicide: sys: trap: fault read addr=0x0 pc=0x0002b6b7

exactly the same happens if I try to format the drive:

	plan9# fossil/flfmt /dev/sdD0/fossil
	cacheLocalData: addr=7841 type got 16 exp 0: tag got 0 exp 6669fe74
	fossil 89: suicide: sys: trap: fault read addr=0x0 pc=0x0002b807

for all it's worth, reading and writing from sdD0 work fine...

Anyway, I have another fossil disk that I can boot and with venti's help
will reinitialize the system. Others may not be that lucky :)

andrey