Created attachment 1161615 [details]
Output of lsof -p <pid> on all ioprocess processes

Description of problem:

The first time IOProcess.truncate() or IOProcess.touch() is called, ioprocess
keep the file open and will never close it.

Typically when using with vdsm, ioprocess will keep the __DIRECT_IO_TEST__ 
file open on shared storage, since the first thing vdsm does is touching
this file.

This is an example output from lsof:

$ lsof -p 23805
COMMAND     PID USER   FD   TYPE DEVICE SIZE/OFF     NODE NAME
...
ioprocess 23805 vdsm    0w   REG   0,39        0 13369358 /rhev/data-center/mnt/10.35.0.179:_home_storage__domains_domain2/__DIRECT_IO_TEST__ (10.35.0.179:/home/storage_domains/domain2)
...

When putting host to maintenance, ioprocess still keeps same file open:

COMMAND     PID USER   FD   TYPE DEVICE SIZE/OFF     NODE NAME
...
ioprocess 23805 vdsm    0w   REG   0,39        0 13369358 /__DIRECT_IO_TEST__
...

Keeping open files on shared storage in maintenance mode may cause trouble
on some shared file systems.

Version-Release number of selected component (if applicable):
0.5.0

The defect was introduce in this commit:

commit 7dec019602137186908fdad624e1cc7d1faf4001
Author:     Yeela Kaplan <ykaplan>
AuthorDate: Sun May 18 17:28:51 2014 +0300
Commit:     Yeela Kaplan <ykaplan>
CommitDate: Sun May 25 19:21:40 2014 +0300

    Add missing functionality to exported functions
    
    touch
    truncatefile

How reproducible:
Always

Steps to Reproduce:
1. Invoke truncate or touch
2. Check open files using lsof -p <ioprocess pid>

Actual results:
File remain open forever.

Expected results:
Truncated or touched file close after the operation.

Workaround:

If the host is in maintenance mode, killing ioprocess will safely close the 
open file.