Revert "Fix issues with truncated files in raw sends"

[behlendorf]

Motivation and Context

Resolve #8540 and #8565 which affect a more common use
case for send/recv.

Description

This partially reverts commit 5dbf8b4. This change resolved
the issues observed with truncated files in raw sends, #7378.
However, the required changes to dnode_allocate() appear
to have introduced a regression for non-raw streams which
needs to be understood, #8540 and #8565.

How Has This Been Tested?

Locally built, pending full CI results. Restores code to previous state.

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.

[tcaputi]

This is a revert, so it looks fine. Some of this will definitely still be necessary in the updated fix

[codecov]

Codecov Report

Merging #8584 into master will increase coverage by 0.09%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #8584      +/-   ##
==========================================
+ Coverage    78.6%   78.69%   +0.09%     
==========================================
  Files         381      381              
  Lines      117526   117525       -1     
==========================================
+ Hits        92384    92490     +106     
+ Misses      25142    25035     -107

Flag	Coverage Δ
#kernel	79.25% <100%> (-0.01%)	⬇️
#user	67.23% <0%> (+0.03%)	⬆️

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[behlendorf]

This was done to ensure continued correct behavior of one of the most heavily used long standing features. Raw send/recv is a great upcoming feature, but it has not yet been released. And won't be until this issue is resolved.

[beren12]

I think your bot had the best responses to this kpande…

"ZFS native encryption is currently broken and not recommended for use due to issue #6845"
and
"ZFS native encryption is currently in TESTING, and not for PRODUCTION use unless you UNDERSTAND THE RISKS. See #6845."

I mean the new bugs have been found but the answer is the same.
At least this isn't all of encryption, just raw sends for it.