[HDFS-15563] Incorrect getTrashRoot return value when a non-snapshottable dir prefix matches the path of a snapshottable dir

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.0
• Fix Version/s: 3.4.0
• Component/s: snapshots
• Labels: pull-request-available
• Assignee: Siyao Meng
• Reporter: Nilotpal Nandi
• Created: 09/Sep/20 10:56
• Updated: 10/Sep/20 11:08
• Resolved: 10/Sep/20 10:25

Description

Note: Only impacts a user if dfs.namenode.snapshot.trashroot.enabled is enabled.

Root cause analysis:

SnapshottableDirectoryStatus paths retrived inside DFSClient#getSnapshotRoot aren't appended with '/', causing some directories with the same path prefix to be mistakenly classified as snapshottable directory.

Thanks shashikant for the test case addition.

—

Repro:

1. snapshottable directory present in the cluster
hdfs lsSnapshottableDir
drwx-x-x 0 hrt_2 hrt_2 0 2020-09-08 07:42 0 65536 /user/hrt_2
drwxr-xr-x 0 hrt_4 hrt_4 0 2020-09-08 13:16 0 65536 /user/hrt_4/newdir/subdir2. Created a new directory outside snapshottable directory
hdfs dfs -mkdir /user/hrt_4/newdir/subdir23. Tried to delete subdir2 , it failed
hdfs dfs -rm -r /user/hrt_4/newdir/subdir2
rm: Failed to move to trash: hdfs://ns1/user/hrt_4/newdir/subdir2: Source /user/hrt_4/newdir/subdir2 and dest /user/hrt_4/newdir/subdir/.Trash/hdfs/Current/user/hrt_4/newdir/subdir2 are not under the same snapshot root.

"/user/hrt_4/newdir/subdir2" , the trash root location is coming to be "/user/hrt_4/newdir/subdir/.Trash"

as clear from the msg here:

rm: Failed to move to trash: hdfs://ns1/user/hrt_4/newdir/subdir2: Source /user/hrt_4/newdir/subdir2 and dest /user/hrt_4/newdir/subdir/.Trash/hdfs/Current/user/hrt_4/newdir/subdir2 are not under the same snapshot root.

Issue Links

• links to: GitHub Pull Request #2295