[HDFS-15614] Initialize snapshot trash root during NameNode startup if enabled

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.0
• Fix Version/s: 3.4.0
• Component/s: namenode, snapshots
• Labels: pull-request-available
• Target Version/s: 3.4.0
• Hadoop Flags: Reviewed
• Assignee: Siyao Meng
• Reporter: Siyao Meng
• Created: 05/Oct/20 12:47
• Updated: 16/Oct/24 18:29
• Resolved: 13/Oct/20 18:10

Description

This is a follow-up to HDFS-15607.

Goal:

Initialize (create) snapshot trash root for all existing snapshottable directories if dfs.namenode.snapshot.trashroot.enabled is set to true. So admins won't have to run dfsadmin -provisionTrash manually on all those existing snapshottable directories.

The change is expected to land in FSNamesystem.

Discussion:
1. Currently in HDFS-15607, the snapshot trash root creation logic is on the client side. But in order for NN to create it at startup, the logic must (also) be implemented on the server side as well. – which is also a requirement by WebHDFS (HDFS-15612).
2. Alternatively, we can provide an extra parameter to the -provisionTrash command like: dfsadmin -provisionTrash -all to initialize/provision trash root on all existing snapshottable dirs.

Issue Links

• causes: HDFS-15820 Ensure snapshot root trash provisioning happens only post safe mode exit
• links to: GitHub Pull Request #2370