Backport HDFS-16509 to branch branch-3.2

[cndaimin]

Fix cherry-pick conflicts.
Tested by TestDecommission#testDecommissionWithUnknownBlock and mvn clean install -DskipTests

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	8m 20s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 1 new or modified test files.
			_ branch-3.2 Compile Tests _
+1 💚	mvninstall	30m 3s		branch-3.2 passed
+1 💚	compile	1m 2s		branch-3.2 passed
+1 💚	checkstyle	0m 52s		branch-3.2 passed
+1 💚	mvnsite	1m 11s		branch-3.2 passed
+1 💚	javadoc	1m 5s		branch-3.2 passed
+1 💚	spotbugs	3m 8s		branch-3.2 passed
+1 💚	shadedclient	15m 58s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 5s		the patch passed
+1 💚	compile	0m 56s		the patch passed
+1 💚	javac	0m 56s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 37s		the patch passed
+1 💚	mvnsite	1m 2s		the patch passed
+1 💚	javadoc	0m 49s		the patch passed
+1 💚	spotbugs	2m 47s		the patch passed
+1 💚	shadedclient	16m 40s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
-1 ❌	unit	190m 10s	/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt	hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 43s		The patch does not generate ASF License warnings.
		274m 15s

Reason	Tests
Failed junit tests	hadoop.hdfs.tools.offlineImageViewer.TestOfflineImageViewer
	hadoop.hdfs.TestReconstructStripedFileWithValidator
	hadoop.hdfs.server.namenode.TestFsck
	hadoop.hdfs.server.blockmanagement.TestBlockManager

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4172/1/artifact/out/Dockerfile
GITHUB PR	#4172
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux ef95e6fb8f5a 4.15.0-112-generic #113-Ubuntu SMP Thu Jul 9 23:41:39 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	branch-3.2 / d36fd04
Default Java	Private Build-1.8.0_312-8u312-b07-0ubuntu1~18.04-b07
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4172/1/testReport/
Max. process+thread count	2810 (vs. ulimit of 5500)
modules	C: hadoop-hdfs-project/hadoop-hdfs U: hadoop-hdfs-project/hadoop-hdfs
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4172/1/console
versions	git=2.17.1 maven=3.6.0 spotbugs=4.2.2
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[cndaimin]

The failed tests looks not related. I will start a new PR to fix the failed tests first.