Re: hio.c does visibilitymap_pin()/IO while holding buffer lock

Hi,

On 2023-03-28 19:17:21 -0700, Andres Freund wrote:
> On 2023-03-28 18:21:02 -0700, Andres Freund wrote:
> > Here's a draft patch.
>
> Attached is v2, with a stupid bug fixed and a bit of comment / pgindent
> polish.

I'd welcome some review (Tomas?), but otherwise I'm planning to push ahead
with this.

I'm still debating with myself whether this commit (or a prerequisite commit)
should move logic dealing with the buffer ordering into
GetVisibilityMapPins(), so we don't need two blocks like this:

if (otherBuffer == InvalidBuffer || targetBlock <= otherBlock)
GetVisibilityMapPins(relation, buffer, otherBuffer,
targetBlock, otherBlock, vmbuffer,
vmbuffer_other);
else
GetVisibilityMapPins(relation, otherBuffer, buffer,
otherBlock, targetBlock, vmbuffer_other,
vmbuffer);
...

if (otherBuffer != InvalidBuffer)
{
if (GetVisibilityMapPins(relation, otherBuffer, buffer,
otherBlock, targetBlock, vmbuffer_other,
vmbuffer))
unlockedTargetBuffer = true;
}
else
{
if (GetVisibilityMapPins(relation, buffer, InvalidBuffer,
targetBlock, InvalidBlockNumber,
vmbuffer, InvalidBuffer))
unlockedTargetBuffer = true;
}
}

Greetings,

Andres Freund