Re: FSM doesn't recover after zeroing damaged page.

Hi!

On Fri, 7 Feb 2025 at 05:15, Anton A. Melnikov
<a(dot)melnikov(at)postgrespro(dot)ru> wrote:
>
> Hi!

> I noticed that the updated page is not written to disk because the
> buffer where it is located is not marked dirty. Moreover MarkBufferDirtyHint(),
> which is called for modified FSM pages, seems is not suitable here,
> since as i suppose the corrupted page must be rewritten certainly, not for hint.

Could you please elaborate? FSM changes are never wal-logged, so it is
possible to read torn pages from a disk (their checksum will mismatch
with the header), so
MarkBufferDirtyHint seems to be completely fine here. I don't think
MarkBufferDirty provides something different from MarkBufferDirtyHint
in the FSM case (because FSM changed are not persistent). At the end
of the day, you just should write a page on a disk sooner or later,
and that's it.

--
Best regards,
Kirill Reshke