HDFS-13538. HDFS DiskChecker should handle disk full situation

[aswinmprabhu]

Description of PR

DiskChecker was enhanced to do checking with some i/o in HADOOP-13738. But this was rolled back partially because of fsync issue seen in HADOOP-15450 and the problem of disk full being flagged as a check failure (HDFS-13538).

This PR tries to address HDFS-13538 and enable i/o based disk checking ONLY for HDFS with a flag that can be turned on in dfs configs.

How was this patch tested?

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running org.apache.hadoop.util.TestDiskCheckerWithDiskIo
[INFO] Tests run: 6, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.129 s -- in org.apache.hadoop.util.TestDiskCheckerWithDiskIo
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 6, Failures: 0, Errors: 0, Skipped: 0


[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  35:00 min
[INFO] Finished at: 2025-08-29T01:17:06+05:30
[INFO] ------------------------------------------------------------------------

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')?
• Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation?
• If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• If applicable, have you updated the LICENSE, LICENSE-binary, NOTICE-binary files?

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	9m 5s		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 _
+0 🆗	mvndep	10m 31s		Maven dependency ordering for branch
+1 💚	mvninstall	20m 53s		trunk passed
+1 💚	compile	8m 28s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	compile	7m 19s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	checkstyle	2m 3s		trunk passed
+1 💚	mvnsite	1m 56s		trunk passed
+1 💚	javadoc	1m 38s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	1m 53s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	3m 24s		trunk passed
+1 💚	shadedclient	22m 23s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+0 🆗	mvndep	0m 21s		Maven dependency ordering for patch
+1 💚	mvninstall	1m 10s		the patch passed
+1 💚	compile	8m 8s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javac	8m 8s		the patch passed
+1 💚	compile	7m 29s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	javac	7m 29s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	2m 2s		the patch passed
+1 💚	mvnsite	1m 53s		the patch passed
+1 💚	javadoc	1m 32s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	1m 49s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	3m 27s		the patch passed
+1 💚	shadedclient	22m 13s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	18m 42s		hadoop-common in the patch passed.
-1 ❌	unit	143m 38s	/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt	hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 47s		The patch does not generate ASF License warnings.
		304m 0s

Reason	Tests
Failed junit tests	hadoop.hdfs.tools.TestDFSAdmin
	hadoop.tools.TestHdfsConfigFields

Subsystem	Report/Notes
Docker	ClientAPI=1.51 ServerAPI=1.51 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7915/1/artifact/out/Dockerfile
GITHUB PR	#7915
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 2e0741537d45 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 / d66bf7a
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-7915/1/testReport/
Max. process+thread count	3390 (vs. ulimit of 5500)
modules	C: hadoop-common-project/hadoop-common hadoop-hdfs-project/hadoop-hdfs U: .
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7915/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[violetnspct]

@aswinmprabhu

Suggested Unit Test Scenarios

File: hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/DiskChecker.java

Method: doDiskIo
Recommended Test Scenarios:

1. Test handling of actual disk failure error message - should be classified as disk failure
2. Test handling of mixed error case where disk is both full and has other issues
3. Test with null/empty error message - should handle gracefully
4. Test with different variations of 'No space left' error messages (case sensitivity, different formats)

File: hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java

Method: checkDirs
Recommended Test Scenarios:

1. Test that when checkDirWithDiskIo flag is disabled, the method calls checkDir()
2. Test that the checkDirWithDiskIo configuration flag properly reads from the configuration settings
3. Test that the method handles null configuration gracefully
4. Test that changing the configuration flag value at runtime properly switches the checking method

Edge Cases to Cover:

1. Configuration flag is false and performs regular checks without disk I/O
2. Same directory path checked with both methods produces consistent results