Incorrect maximum DVA value in DDE_GET_NDVAS()

[dweeezil]

The conditional was reversed which caused garbage values to be used when
calculating dds_ref_dsize.

Description

Fixed the conditional.

Motivation and Context

Discovered while porting the vdev evacuation code. This problem caused bogus values to be stored both in-core and on-disk for dds_ref_dsize which should show up in, for example, zpool status -D <pool> as wild values for DSIZE. It has the effect of, among other things, causing dsl_pool_adjustedsize() to return bogus values.

How Has This Been Tested?

I used the following reproducer script and observed the value of DSIZE:

#!/bin/sh

truncate -s 1g tank.img
zpool create tank $(pwd)/tank.img
[ -f tank.key ] || dd if=/dev/urandom of=tank.key bs=32 count=1 > /dev/null 2>&1
zfs create -o dedup=on -o encryption=on -o keyformat=raw -o keylocation=file://`pwd`/tank.key tank/fs
yes | dd bs=1M count=100 iflag=fullblock of=/tank/fs/yes
zpool status -D tank

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.
• All new and existing tests passed.
• All commit messages are properly formatted and contain Signed-off-by.
• Change has been approved by a ZFS on Linux member.

[codecov]

Codecov Report

Merging #7234 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7234      +/-   ##
==========================================
- Coverage   76.52%   76.51%   -0.02%     
==========================================
  Files         327      327              
  Lines      103864   103864              
==========================================
- Hits        79487    79473      -14     
- Misses      24377    24391      +14

Flag	Coverage Δ
#kernel	76.38% <ø> (+0.09%)	⬆️
#user	65.96% <ø> (-0.03%)	⬇️

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[tcaputi]

whoops. Sorry about that. Thanks for fixing this.

[behlendorf]

Nice work! LGTM.