Bug 1309186

Description of problem:
========================
When a volume is mounted on NFS and , I started to perform IOs using dd command in loop and found that if i restarted NFS process during the IOs, I get the following error for a file which is being created/written at that point of time


>>dd: failed to open ‘smf.17’: Too many levels of symbolic links


Following is the dmesg log of the client:
===================================
 [2405704.573740] SELinux: initialized (dev 0:42, type nfs), uses genfs_contexts
<nag> [2480898.670390] VFS: Lookup of 'smf.107' in nfs 0:42 would have caused loop
<nag> [2481059.716509] VFS: Lookup of 'smf.227' in nfs 0:42 would have caused loop
<nag> [2481537.243509] VFS: Lookup of 'smf.17' in nfs 0:42 would have caused loop





Version-Release number of selected component (if applicable):
=================
3.7.5-19


How reproducible:
===================
reporduced it twice on two different clients

Steps to Reproduce:
1. create a volume and start it
2.mount it on nfs client
3. start IOs using dd command in loop to create files as below:
for i in {1..100000};do dd if=/dev/urandom of=smf.$i bs=1024 count=10000;done 
4. Now force start the volume(to cause a restart of nfs process) while the IOs are happening. We can see the following error for the file which is being created at that point of time.


>>dd: failed to open ‘smf.17’: Too many levels of symbolic links


Also the file create fails 
Following is the dmesg log of the client:
===================================
 [2405704.573740] SELinux: initialized (dev 0:42, type nfs), uses genfs_contexts
<nag> [2480898.670390] VFS: Lookup of 'smf.107' in nfs 0:42 would have caused loop
<nag> [2481059.716509] VFS: Lookup of 'smf.227' in nfs 0:42 would have caused loop
<nag> [2481537.243509] VFS: Lookup of 'smf.17' in nfs 0:42 would have caused loop