I just noticed that in some cases the shutdown sequence that came with
Debian 1.3 is not completely optimal, as it can cause filesystems not to
be properly finalized or leave NFS mounts hanging (e.g. kills pppd
before umounting the NFS mounts).
Although the scripting is not really a kernel issue, the kernel could
help here by maintaining a list of resources that are dependant on each
other. For example, imagine the following constellation: A computer
using NFSroot, having a ppp link open, an NFS mount over this link and a
program using data on the second mount. The resources would depend on
each other in the following way:
nfsroot
pppd
nfs mount
program
When the system shuts down, first of all, the programs get killed (pppd
hangs up, program exits [race condition, usually pppd wins :-( ]), then
the system tries to remove the nfs mount (Network is unreachable), then
shuts down nfsroot and halts. IMHO the condition that two resources are
dependant upon each other should be recognized properly, and the
resources should be freed in the right order.
This would require tracking nfs, network interfaces (could the kernel
possibly control a PPP link without pppd running?), swap files, and some
other things that may be important but I can't think of after working
eight hours. :-)
CU
Simon
PS: Please CC me, I'm not on the list.
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