[HDFS-10825] Snapshot read can reveal future bytes if snapshotted while writing

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.7.2
• Fix Version/s: 2.9.0, 3.0.0-beta1
• Component/s: hdfs

Environment

HDFS-2.7.2, see attached unittest file.

• Assignee: Manoj Govindassamy
• Reporter: Abhishek Rai
• Created: 01/Sep/16 04:12
• Updated: 25/Aug/17 21:44
• Resolved: 25/Aug/17 21:44

Description

The following sequence of steps will produce extra bytes, that should not be visible, because they are not in the snapshot.

• Create a new file for writing.
• Write "hello world"
• Invoke hsync() on the file handle.
• Create a snapshot, keep the file open.
• Append another "hello world" string to the same file handle.
• Close the file.
• Read file in the snapshot (not the current file).
• Output is "hello worldhello world" instead of the expected snapshot contents of "hello world".

Issue Links

• duplicates: HDFS-11402 HDFS Snapshots should capture point-in-time copies of OPEN files
• relates to: HDFS-7263 Snapshot read can reveal future bytes for appended files.