HDFS-17812. Reset curEntry when BlockIteratorImpl checks a new subdir

[kokonguyen191]

Description of PR

1. BlockIteratorImpl#getSubdirEntries sorts by strings, meaning subdir29 comes before subdir4, which can result in a bigger block id being listed before a smaller block id
2. If block cleanup happens before state.curEntry is reset to null, stale data can carry over into the next loop
3. Search for a bigger ID than the range in nextSorted(entries, state.curEntry) -> null -> subdir is skipped.

Usually happens during DiskBalancer operations.

How was this patch tested?

UT

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	8m 26s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets 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.
			_ trunk Compile Tests _
+1 💚	mvninstall	27m 12s		trunk passed
+1 💚	compile	0m 45s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	compile	0m 41s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	checkstyle	0m 39s		trunk passed
+1 💚	mvnsite	0m 47s		trunk passed
+1 💚	javadoc	0m 41s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	1m 3s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	1m 40s		trunk passed
+1 💚	shadedclient	21m 53s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 37s		the patch passed
+1 💚	compile	0m 38s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javac	0m 38s		the patch passed
+1 💚	compile	0m 33s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	javac	0m 33s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 30s		the patch passed
+1 💚	mvnsite	0m 38s		the patch passed
+1 💚	javadoc	0m 34s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	1m 3s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	1m 37s		the patch passed
+1 💚	shadedclient	21m 36s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	96m 58s		hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 30s		The patch does not generate ASF License warnings.
		188m 53s

Subsystem	Report/Notes
Docker	ClientAPI=1.51 ServerAPI=1.51 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7826/1/artifact/out/Dockerfile
GITHUB PR	#7826
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 90a95af80fa7 5.15.0-142-generic #152-Ubuntu SMP Mon May 19 10:54:31 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 7c432ab
Default Java	Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7826/1/testReport/
Max. process+thread count	3597 (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-7826/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
Powered by	Apache Yetus 0.14.0 https://yetus.apache.org

This message was automatically generated.

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 20s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets 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.
			_ trunk Compile Tests _
+1 💚	mvninstall	26m 11s		trunk passed
+1 💚	compile	0m 46s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	compile	0m 42s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	checkstyle	0m 38s		trunk passed
+1 💚	mvnsite	0m 45s		trunk passed
+1 💚	javadoc	0m 43s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	1m 4s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	1m 41s		trunk passed
+1 💚	shadedclient	21m 49s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 33s		the patch passed
+1 💚	compile	0m 38s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javac	0m 38s		the patch passed
+1 💚	compile	0m 38s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	javac	0m 38s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 28s		the patch passed
+1 💚	mvnsite	0m 38s		the patch passed
+1 💚	javadoc	0m 33s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	1m 2s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	1m 43s		the patch passed
+1 💚	shadedclient	21m 35s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	110m 38s		hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 25s		The patch does not generate ASF License warnings.
		193m 16s

Subsystem	Report/Notes
Docker	ClientAPI=1.51 ServerAPI=1.51 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7826/3/artifact/out/Dockerfile
GITHUB PR	#7826
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 86062c8ad401 5.15.0-142-generic #152-Ubuntu SMP Mon May 19 10:54:31 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 39607c4
Default Java	Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7826/3/testReport/
Max. process+thread count	3459 (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-7826/3/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
Powered by	Apache Yetus 0.14.0 https://yetus.apache.org

This message was automatically generated.

[kokonguyen191]

Hi @ZanderXu, can you take a look when you're free? Thanks!

[github-actions]

We're closing this stale PR because it has been open for 100 days with no activity. This isn't a judgement on the merit of the PR in any way. It's just a way of keeping the PR queue manageable.
If you feel like this was a mistake, or you would like to continue working on it, please feel free to re-open it and ask for a committer to remove the stale tag and review again.
Thanks all for your contribution.