kern/openzfs: Apply the essential part of FreeBSD-EN-23:18.openzfs. (stable/13)

[seigo.tanimura_gmail.com]

Summary

Avoid piling up the ARC pruning tasks when it is running.

The fix for FreeBSD-EN-23:18.openzfs is for OpenZFS 2.2, so it cannot be
applied directly to stable/13.

PR: 275594
Reported By: Thomas Mueller <[e-mail]>
Security: FreeBSD-EN-23:18.openzfs
Signed-off-by: Seigo Tanimura <[e-mail]>

[seigo.tanimura_gmail.com]

Target branches: stable/13, releng/13.3, releng/13.2

[olce]

I agree with this simple, stopgap measure. It is indeed what FreeBSD-EN-23:18.openzfs achieves, in a much simpler way.

Just to be sure, I'm currently trying to reproduce some of the PR 275594's problems without and with this patch.

Then, going to liaise with upstream to see if they plan to MFC FreeBSD-EN-23:18.openzfs. If they don't, I'll push that patch upstream as well.

[seigo.tanimura_gmail.com]

Hello @olce,

Are you going to apply this change to stable/13 only, or "backport" it to main first?

I have to ask that because main and stable/14 already have the equivalent fix.

[olce]

Hi Seigo,

In D44170#1018956, @seigo.tanimura_gmail.com wrote:

Hello @olce,

Are you going to apply this change to stable/13 only, or "backport" it to main first?

I have to ask that because main and stable/14 already have the equivalent fix.

This change is to be applied to stable/13 only (obviously). So maybe I'm not understanding your question?

Sorry for the slow progress, I've been ill for a few days (hopefully coming to an end today/tomorrow) so could not work more than a few hours.

To clarify the next steps for this precise change:

• Commit it to stable/13.
• Ensure that either this fix or the full change in FreeBSD-EN-23:18.openzfs is committed to OpenZFS 2.1.x (so that, at the next import in stable/13, we don't lose the fix).
• Possibly issue an EN for releng/13.3 (but for this we may wait a bit to see which other fixes should be included to solve/mitigate the reported problems).

[seigo.tanimura_gmail.com]

Hello @olce,

This change is to be applied to stable/13 only (obviously). So maybe I'm not understanding your question?

That has clarified my question, thanks!

The upcoming steps looks good on my side as well.

[olce]

Going to be superseded by a backport of FreeBSD-EN-23:18.openzfs to OpenZFS 2.1.x and FreeBSD's stable/13.

Please see the recent report in the bug (PR 275594).

Thanks.

[olce]

Closing, since superseded by an upstream fix.