Hiroshi.  ReleaseRelationBuffers now removes rel's buffers from pool,
instead of merely marking them nondirty.  The old code would leave valid
buffers for a deleted relation, which didn't cause any known problems
but can't possibly be a good idea.  There were several places which called
ReleaseRelationBuffers *and* FlushRelationBuffers, which is now
unnecessary; but there were others that did not.  FlushRelationBuffers
no longer emits a warning notice if it finds dirty buffers to flush,
because with the current bufmgr behavior that's not an unexpected
condition.  Also, FlushRelationBuffers will flush out all dirty buffers
for the relation regardless of block number.  This ensures that
pg_upgrade's expectations are met about tuple on-row status bits being
up-to-date on disk.  Lastly, tweak BufTableDelete() to clear the
buffer's tag so that no one can mistake it for being a still-valid
buffer for the page it once held.  Formerly, the buffer would not be
found by buffer hashtable searches after BufTableDelete(), but it would
still be thought to belong to its old relation by the routines that
sequentially scan the shared-buffer array.  Again I know of no bugs
caused by that, but it still can't be a good idea.

whether to do fsync or not, and if so (which should be seldom) just
do the fsync immediately.  This way we need not build data structures
in md.c/fd.c for blind writes.

as a shared dirtybit for each shared buffer.  The shared dirtybit still
controls writing the buffer, but the local bit controls whether we need
to fsync the buffer's file.  This arrangement fixes a bug that allowed
some required fsyncs to be missed, and should improve performance as well.
For more info see my post of same date on pghackers.

In the event of an elog() while the mode was set to immediate write,
there was no way for it to be set back to the normal delayed write.
The mechanism was a waste of space and cycles anyway, since the only user
was varsup.c, which could perfectly well call FlushBuffer directly.
Now it does just that, and the notion of a write mode is gone.

running gcc and HP's cc with warnings cranked way up.  Signed vs unsigned
comparisons, routines declared static and then defined not-static,
that kind of thing.  Tedious, but perhaps useful...

  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc

to all files copyright Regents of Berkeley.  Man, that's a lot of files.

and elog(ERROR) inside bufmgr.