Description of problem:
High CPU usage for glusterfsd process when thin LV is 100% full. This can lead to crash and should be handled.


Version-Release number of selected component (if applicable):
RHGS-3.1
glusterfs-server-3.7.9-12.el7rhgs.x86_64

Reproducible:

Not very easy to reproduce as we need 100% LV full with FS space available.
Theoretically we should be able to reproduce this issue. As LV in question here is thin LV, on deleting(running rm) a file, filesystem usage will be reclaimed but LV usage won't decrease. Thus we can end up in a situation where LV is full but FS still has ample to space.

Steps to Reproduce:
1. Create a volume
2. Fill it with data such that brick LV is 100% full but FS still has space left 


Actual results:
Brick process CPU consumption goes high when LV reaches 100% full.

Expected results:
100% LV usage should be intercepted for XFS and ultimately by gluster and appropriate action should be performed.

Additional info:

I am not sure if this is a expected behavior or this is a bug. But it is worth looking into issue once