Possible problem with WAPBL on FFSV1

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

	Hello.  Recently I saw a panic on two different 9.2_stable machines involving the
filesystem.  The two machines in question are virtual machines, running under Xen, but I don't
think that's relevant here.  While I'm not sure what the initial panic message was, since they
were rebooted by an external monitoring script, the result was that they would continually
panic when a specific directory was accessed.

Setup:
Both machines are running a single FFSV1 root filesystem and one directory has over 32,000
files in it.  This directory is continually appended and, once a day, files are purged from
it.  When the panic occurs, the systems reboot, run their WAPBL logs, don't check the
filesystem and, once they access the very large directory, panic again.

Once I brought up the VM's single user and ran fsck against the root filesystem, fsck
complained that the very large directory contained empty blocks.  I told it to clean the
filesystem and it advised me to run fsck against the same filesystem when I was done with the
current run of fsck.  I did, it checked out okay, and things seem to be running again without a
problem.

	My concern here is that the filesystem can get into a state where WAPBL's journal cannot
correct the filesystem. Since I'm pretty sure there was no memory corruption or disk corruption,
especially not on two different VM's, I'm wondering if anyone else has seen a problem with
WAPBL on FFSV1 with large  directories?

-thanks
-Brian