Description of problem:
-----------------------
Write-behind has got the option, write-behind-window-size which, as per command link help, should allow values within range [524288 - 1073741824]
But in this case, it takes values greater than MAX value - 1073741824

Version-Release number of selected component (if applicable):
-------------------------------------------------------------
RHS2.1 - glusterfs-3.4.0.15rhs-1


How reproducible:
-----------------
Always

Steps to Reproduce:
-------------------

1. Set 'write-behind-window-size' to negative value
(i.e) gluster volume set <vol-name> performance.write-behind-window-size -1

This would show-up an error, with valid value range, which is [524288 - 1073741824]

2. After getting the max value from step 1, try to set 'write-behind-window-size' greater than that value 
(i.e) gluster volume set <vol-name> performance.write-behind-window-size 1073741825


Actual results:
The value greater than MAX value is allowed to be set

Expected results:
Any value greater than MAX value should be failed to set

Additional info:
1. Volume Information
----------------------
Its a distributed volume with 2 bricks

[Tue Aug  6 06:54:44 UTC 2013 root.37.205:~ ] # gluster volume info distvol
 
Volume Name: distvol
Type: Distribute
Volume ID: 562ebca3-a048-4c1d-87d4-d6ad36547092
Status: Started
Number of Bricks: 2
Transport-type: tcp
Bricks:
Brick1: 10.70.37.205:/rhs/brick4/distbrick1
Brick2: 10.70.37.52:/rhs/brick4/distbrick1
Options Reconfigured:
performance.write-behind-window-size: 107374182400
performance.read-ahead-page-count: 1
performance.cache-size: 4MB
server.allow-insecure: on
nfs.rpc-auth-allow: on
performance.md-cache-timeout: 60

[Tue Aug  6 06:56:04 UTC 2013 root.37.205:~ ] # gluster volume status distvol
Status of volume: distvol
Gluster process                                         Port    Online  Pid
------------------------------------------------------------------------------
Brick 10.70.37.205:/rhs/brick4/distbrick1               49155   Y       2854
Brick 10.70.37.52:/rhs/brick4/distbrick1                49155   Y       2841
NFS Server on localhost                                 2049    Y       15889
NFS Server on 10.70.37.52                               2049    Y       15396
NFS Server on 10.70.37.202                              2049    Y       15411
NFS Server on 10.70.37.154                              2049    Y       15417
 
There are no active volume tasks

2. Console logs
----------------
[Tue Aug  6 06:41:13 UTC 2013 root.37.205:~ ] # gluster volume set distvol performance.write-behind-window-size 0
volume set: failed: '0' in 'option cache-size 0' is out of range [524288 - 1073741824]                                                                                                                         
[Tue Aug  6 06:41:38 UTC 2013 root.37.205:~ ] # gluster volume set distvol performance.write-behind-window-size 524287
volume set: failed: '524287' in 'option cache-size 524287' is out of range [524288 - 1073741824]                                                                                                               
[Tue Aug  6 06:41:48 UTC 2013 root.37.205:~ ] # gluster volume set distvol performance.write-behind-window-size 524288
volume set: success                                                                                                                                                                                            
[Tue Aug  6 06:41:55 UTC 2013 root.37.205:~ ] # gluster volume set distvol performance.write-behind-window-size 1073741824
volume set: success                                                                                                                                                                                            
[Tue Aug  6 06:42:11 UTC 2013 root.37.205:~ ] # gluster volume set distvol performance.write-behind-window-size 1073741825
volume set: success                                                                                                                                                                                            
[Tue Aug  6 06:42:17 UTC 2013 root.37.205:~ ] # gluster volume set distvol performance.write-behind-window-size 107374182400                                                                             
volume set: success                                                                                                                                                                                            
[Tue Aug  6 06:42:32 UTC 2013 root.37.205:~ ] # glusterfs -V                                                                                                                                             
glusterfs 3.4.0.15rhs built on Aug  4 2013 22:34:15                                                                                                                                                            
Repository revision: git://git.gluster.com/glusterfs.git                                                                                                                                                       
Copyright (c) 2006-2013 Red Hat, Inc. <http://www.redhat.com/>
GlusterFS comes with ABSOLUTELY NO WARRANTY.
It is licensed to you under your choice of the GNU Lesser
General Public License, version 3 or any later version (LGPLv3
or later), or the GNU General Public License, version 2 (GPLv2),
in all cases as published by the Free Software Foundation.

[Tue Aug  6 06:54:44 UTC 2013 root.37.205:~ ] # gluster volume info distvol
 
Volume Name: distvol
Type: Distribute
Volume ID: 562ebca3-a048-4c1d-87d4-d6ad36547092
Status: Started
Number of Bricks: 2
Transport-type: tcp
Bricks:
Brick1: 10.70.37.205:/rhs/brick4/distbrick1
Brick2: 10.70.37.52:/rhs/brick4/distbrick1
Options Reconfigured:
performance.write-behind-window-size: 107374182400
performance.read-ahead-page-count: 1
performance.cache-size: 4MB
server.allow-insecure: on
nfs.rpc-auth-allow: on
performance.md-cache-timeout: 60