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Fix infinite scan on a pool with only special allocations. #10106

Merged
merged 1 commit into from
Mar 12, 2020
Merged

Fix infinite scan on a pool with only special allocations. #10106

merged 1 commit into from
Mar 12, 2020

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amotin
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@amotin amotin commented Mar 6, 2020 •
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Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

How Has This Been Tested?

It was tested on FreeBSD head by running:

# mdconfig -a -t swap -s 1g
md0
# mdconfig -a -t swap -s 1g
md1
# zpool create qqq md0 special md1
# zpool scrub qqq
# zpool status qqq
# zpool destroy qqq

Without the patch the scrub eats a lot of CPU and never completes.

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)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Documentation (a change to man pages or other documentation)

Checklist:

  • My code follows the ZFS on Linux code style requirements.
  • I have updated the documentation accordingly.
  • I have read the contributing document.
  • I have added tests to cover my changes.
  • I have run the ZFS Test Suite with this change applied.
  • All commit messages are properly formatted and contain Signed-off-by.

@amotin
Fix infinite scan on a pool with only special allocations.
fe0af5f 
Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
@amotin
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amotin commented Mar 6, 2020

I am not sure why is this limit is needed at all, but, assuming there was some reason, I just fixed it.

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amotin commented Mar 6, 2020

@tcaputi @don-brady ^^^

@behlendorf behlendorf added the Status: Code Review Needed Ready for review and testing label Mar 7, 2020
behlendorf
behlendorf approved these changes Mar 9, 2020
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Nice find. I agree, we need to be including these other classes in this calculation.

@amotin amotin mentioned this pull request Mar 9, 2020
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amotin commented Mar 9, 2020

This PR fixes issue #8694

@amotin amotin linked an issue Mar 10, 2020 that may be closed by this pull request
scrub never completes on empty pool with special vdev #8694
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@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Mar 11, 2020
@behlendorf behlendorf merged commit fa130e0 into openzfs:master Mar 12, 2020
tonyhutter pushed a commit to tonyhutter/zfs that referenced this pull request Apr 15, 2020
@amotin @tonyhutter
Fix infinite scan on a pool with only special allocations
ee54c0d 
Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
Closes openzfs#10106 
Closes openzfs#8694
tonyhutter pushed a commit to tonyhutter/zfs that referenced this pull request Apr 22, 2020
@amotin @tonyhutter
Fix infinite scan on a pool with only special allocations
1228c55 
Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
Closes openzfs#10106 
Closes openzfs#8694
tonyhutter pushed a commit to tonyhutter/zfs that referenced this pull request Apr 22, 2020
@amotin @tonyhutter
Fix infinite scan on a pool with only special allocations
7a11fe6 
Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
Closes openzfs#10106 
Closes openzfs#8694
tonyhutter pushed a commit to tonyhutter/zfs that referenced this pull request Apr 28, 2020
@amotin @tonyhutter
Fix infinite scan on a pool with only special allocations
ced8dec 
Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
Closes openzfs#10106 
Closes openzfs#8694
tonyhutter pushed a commit that referenced this pull request May 12, 2020
@amotin @tonyhutter
Fix infinite scan on a pool with only special allocations
4e55349 
Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
Closes #10106 
Closes #8694
jsai20 pushed a commit to jsai20/zfs that referenced this pull request Mar 30, 2021
@amotin @jsai20
Fix infinite scan on a pool with only special allocations
0cfe592 
Attempt to run scrub or resilver on a new pool containing only special
allocations (special vdev added on creation) caused infinite loop
because of dsl_scan_should_clear() limiting memory usage to 5% of pool
size, which it calculated accounting only normal allocation class.

Addition of special and just in case dedup classes fixes the issue.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
Closes openzfs#10106 
Closes openzfs#8694
@amotin amotin deleted the special_scrub branch August 24, 2021 20:17
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scrub never completes on empty pool with special vdev
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