Re: Increase of buffers usage count by bgwriter

I wrote:
> ITAGAKI Takahiro <itagaki.takahiro@lab.ntt.co.jp> writes:
>> I found that bgwriter increments usage count of buffers when it writes
>> the buffers. I feel this behavior is strange, because the behavior of
>> bgwriter will affect buffer management strategy.

> I think it might be sufficient to not increment usage_count when
> UnpinBuffer's "trashOK" parameter is false --- that's what
> SyncOneBuffer passes, so it'd fix the issue for bgwriter activity,
> and arguably all the other call sites that pass false also don't
> want the count to increment.

I've committed a change along this line.  Thanks for the suggestion!
        regards, tom lane