[HDFS-5933] Optimize the FSImage layout for ACLs

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: HDFS ACLs (HDFS-4685)
• Fix Version/s: HDFS ACLs (HDFS-4685)
• Component/s: hdfs-client, namenode, security
• Target Version/s: HDFS ACLs (HDFS-4685)
• Hadoop Flags: Reviewed
• Assignee: Haohui Mai
• Reporter: Haohui Mai
• Created: 11/Feb/14 22:25
• Updated: 12/Feb/14 22:58
• Resolved: 12/Feb/14 22:58

Description

The current serialization of the ACLs is suboptimal. ACL entries should be serialized using the same scheme that the PB-based FSImage serializes permissions.

An ACL entry is represented by a 32-bit integer in Big Endian format. The bits can be divided in four segments:
[0:2) || [2:26) || [26:27) || [27:29) || [29:32)

[0:2) – reserved for futute uses.
[2:26) – the name of the entry, which is an ID that points to a string in the StringTableSection.
[26:27) – the scope of the entry (AclEntryScopeProto)
[27:29) – the type of the entry (AclEntryTypeProto)
[29:32) – the permission of the entry (FsActionProto)

Issue Links

• depends upon: HDFS-5923 Do not persist the ACL bit in the FsPermission
• is required by: HDFS-5937 Fix TestOfflineEditsViewer on HDFS-4685 branch.
• relates to: HDFS-4685 Implementation of ACLs in HDFS