[HDFS-4140] fuse-dfs handles open(O_TRUNC) poorly

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.2-alpha
• Fix Version/s: 2.0.3-alpha
• Component/s: fuse-dfs
• Hadoop Flags: Reviewed
• Assignee: Colin McCabe
• Reporter: Andy Isaacson
• Created: 01/Nov/12 22:23
• Updated: 15/Feb/13 13:12
• Resolved: 18/Dec/12 02:45

Description

fuse-dfs handles open(O_TRUNC) poorly.

It is converted to multiple fuse operations. Those multiple fuse operations often fail (for example, calling fuse_truncate_impl() while a file is also open for write results in a "multiple writers!" exception.)

One easy way to see the problem is to run the following sequence of shell commands:

ubuntu@ubu-cdh-0:~$ echo foo > /export/hdfs/tmp/a/t1.txt
ubuntu@ubu-cdh-0:~$ ls -l /export/hdfs/tmp/a
total 0
-rw-r--r-- 1 ubuntu hadoop 4 Nov  1 15:21 t1.txt
ubuntu@ubu-cdh-0:~$ hdfs dfs -ls /tmp/a
Found 1 items
-rw-r--r--   3 ubuntu hadoop          4 2012-11-01 15:21 /tmp/a/t1.txt
ubuntu@ubu-cdh-0:~$ echo bar > /export/hdfs/tmp/a/t1.txt
ubuntu@ubu-cdh-0:~$ ls -l /export/hdfs/tmp/a
total 0
-rw-r--r-- 1 ubuntu hadoop 0 Nov  1 15:22 t1.txt
ubuntu@ubu-cdh-0:~$ hdfs dfs -ls /tmp/a
Found 1 items
-rw-r--r--   3 ubuntu hadoop          0 2012-11-01 15:22 /tmp/a/t1.txt