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Set spa_final_txg in spa_unload() #17395

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Merged
merged 1 commit into from
May 30, 2025
Merged

Set spa_final_txg in spa_unload() #17395

merged 1 commit into from
May 30, 2025

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amotin
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@amotin amotin commented May 29, 2025 •
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I've noticed that after some dedup tests system reboot ends up in assertion about ms_defer tree not empty. It seems to be caused by DDT flushing still freeing some blocks while ZFS trying to reach a final steady state due to spa_final_txg, while being set by spa_export_common() on pool export, is not set when spa_unload() is called by spa_evict_all() on system reboot/shutdown. Setting spa_final_txg in spa_unload() fixes this issue.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Performance enhancement (non-breaking change which improves efficiency)
  • Code cleanup (non-breaking change which makes code smaller or more readable)
  • Quality assurance (non-breaking change which makes the code more robust against bugs)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
  • Documentation (a change to man pages or other documentation)

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@amotin
Set spa_final_txg in spa_unload()
31b8962 
I've noticed that after some dedup tests system reboot ends up in
assertion about ms_defer tree not free.  It seems to be caused by
DDT flushing still freeing some blocks while ZFS trying to reach
a final steady state due to spa_final_txg, while being set by
spa_export_common() on pool export, is not set when spa_unload()
is called by spa_evict_all() on system reboot/shutdown.  Setting
spa_final_txg in spa_unload() fixes this issue.

Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
robn
robn approved these changes May 29, 2025
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Yeah, nice. Our chat history suggests we've looked sideways at this a couple of times in the last couple of years, but apparently it was never quite the thing, so we didn't stop. I'm glad I recognised it at least :)

@amotin amotin added the Status: Code Review Needed Ready for review and testing label May 29, 2025
behlendorf
behlendorf approved these changes May 29, 2025
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Good find.

@amotin amotin added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels May 30, 2025
pcd1193182
pcd1193182 approved these changes May 30, 2025
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Just the one question. It's certainly not a big deal, though, I would be happy with the PR in its current state.

@amotin amotin merged commit 008c966 into openzfs:master May 30, 2025
47 of 55 checks passed
@amotin amotin deleted the final_txg branch May 30, 2025 18:44
behlendorf pushed a commit to behlendorf/zfs that referenced this pull request Jun 13, 2025
@amotin @behlendorf
Set spa_final_txg in spa_unload()
59a46cc 
I've noticed that after some dedup tests system reboot ends up in
assertion about ms_defer tree not free.  It seems to be caused by
DDT flushing still freeing some blocks while ZFS trying to reach
a final steady state due to spa_final_txg, while being set by
spa_export_common() on pool export, is not set when spa_unload()
is called by spa_evict_all() on system reboot/shutdown.  Setting
spa_final_txg in spa_unload() fixes this issue.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Rob Norris <rob.norris@klarasystems.com>
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes openzfs#17395
behlendorf pushed a commit that referenced this pull request Jun 17, 2025
@amotin @behlendorf
Set spa_final_txg in spa_unload()
b716112 
I've noticed that after some dedup tests system reboot ends up in
assertion about ms_defer tree not free.  It seems to be caused by
DDT flushing still freeing some blocks while ZFS trying to reach
a final steady state due to spa_final_txg, while being set by
spa_export_common() on pool export, is not set when spa_unload()
is called by spa_evict_all() on system reboot/shutdown.  Setting
spa_final_txg in spa_unload() fixes this issue.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Rob Norris <rob.norris@klarasystems.com>
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #17395
behlendorf pushed a commit to behlendorf/zfs that referenced this pull request Jun 17, 2025
@amotin @behlendorf
Set spa_final_txg in spa_unload()
bf4baee 
I've noticed that after some dedup tests system reboot ends up in
assertion about ms_defer tree not free.  It seems to be caused by
DDT flushing still freeing some blocks while ZFS trying to reach
a final steady state due to spa_final_txg, while being set by
spa_export_common() on pool export, is not set when spa_unload()
is called by spa_evict_all() on system reboot/shutdown.  Setting
spa_final_txg in spa_unload() fixes this issue.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Rob Norris <rob.norris@klarasystems.com>
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes openzfs#17395
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@robn robn robn approved these changes

@pcd1193182 pcd1193182 pcd1193182 approved these changes

@behlendorf behlendorf behlendorf approved these changes

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@amotin @robn @pcd1193182 @behlendorf