Description of problem:
While executing the fs-sanity test suite, the tiering volume throws a segfault

Version-Release number of selected component (if applicable):
glusterfs-3.7.5-1.el7.x86_64
nfs-ganesha-2.3-0.rc6.el7.centos.x86_64

How reproducible:
happen to be first time

Steps to Reproduce:
1. create volume of dist-rep type with tiering enabled.
2. export the volume for nfs-ganesha and mount it with vers=4
3. start executing the fs-sanity test suite

Actual results:
[2015-10-19 16:14:14.701640] E [MSGID: 109037] [tier.c:951:tier_start] 0-vol2-tier-dht: Demotion failed!
[2015-10-19 16:16:00.720267] I [MSGID: 109038] [tier.c:586:tier_build_migration_qfile] 0-vol2-tier-dht: Failed to remove /var/run/gluster/vol2-tier-dht/demotequeryfile-vol2-tier-dht
pending frames:
frame : type(0) op(0)
frame : type(0) op(0)
frame : type(0) op(0)
patchset: git://git.gluster.com/glusterfs.git
signal received: 11
time of crash: 
2015-10-19 16:16:00
configuration details:
argp 1
backtrace 1
dlfcn 1
libpthread 1
llistxattr 1
setfsid 1
spinlock 1
epoll.h 1
xattr.h 1
st_atim.tv_nsec 1
package-string: glusterfs 3.7.5
/lib64/libglusterfs.so.0(_gf_msg_backtrace_nomem+0xb2)[0x7fc0dab7c002]
/lib64/libglusterfs.so.0(gf_print_trace+0x31d)[0x7fc0dab9848d]
/lib64/libc.so.6(+0x35650)[0x7fc0d926a650]
/lib64/libc.so.6(+0x86811)[0x7fc0d92bb811]
/usr/lib64/libgfdb.so.0(gf_sql_query_function+0x101)[0x7fc0cc3e4001]
/usr/lib64/libgfdb.so.0(gf_sqlite3_find_unchanged_for_time+0xd0)[0x7fc0cc3e55d0]
/usr/lib64/libgfdb.so.0(find_unchanged_for_time+0x41)[0x7fc0cc3dfbd1]
/usr/lib64/glusterfs/3.7.5/xlator/cluster/tier.so(+0x57947)[0x7fc0cca0f947]
/lib64/libpthread.so.0(+0x7df5)[0x7fc0d99e4df5]
/lib64/libc.so.6(clone+0x6d)[0x7fc0d932b1ad]
---------
(END)



(gdb) bt
#0  __strlen_sse2 () at ../sysdeps/x86_64/strlen.S:31
#1  0x00007fc0cc3e4001 in gf_sql_query_function (prep_stmt=0x7fc0a042b288, query_callback=query_callback@entry=0x7fc0cca0d640 <tier_gf_query_callback>, _query_cbk_args=_query_cbk_args@entry=0x7fc0b17f9e70)
    at gfdb_sqlite3_helper.c:1157
#2  0x00007fc0cc3e55d0 in gf_sqlite3_find_unchanged_for_time (db_conn=0x7fc0a0445440, query_callback=0x7fc0cca0d640 <tier_gf_query_callback>, query_cbk_args=0x7fc0b17f9e70, for_time=0x7fc0b17f9e60)
    at gfdb_sqlite3.c:809
#3  0x00007fc0cc3dfbd1 in find_unchanged_for_time (_conn_node=<optimized out>, query_callback=0x7fc0cca0d640 <tier_gf_query_callback>, _query_cbk_args=0x7fc0b17f9e70, for_time=0x7fc0b17f9e60)
    at gfdb_data_store.c:506
#4  0x00007fc0cca0f947 in tier_process_brick_cbk (args=<synthetic pointer>, local_brick=0x7fc0b8003680) at tier.c:501
#5  tier_build_migration_qfile (is_promotion=_gf_false, query_cbk_args=0x7fc0b17f9e70, args=0x7fc0c501ecc0) at tier.c:606
#6  tier_demote (args=0x7fc0c501ecc0) at tier.c:666
#7  0x00007fc0d99e4df5 in start_thread (arg=0x7fc0b17fa700) at pthread_create.c:308
#8  0x00007fc0d932b1ad in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113


# gluster volume status vol2
Status of volume: vol2
Gluster process                             TCP Port  RDMA Port  Online  Pid
------------------------------------------------------------------------------
Hot Bricks:
Brick 10.70.46.60:/rhs/brick2/cold-d2r21    49158     0          Y       16128
Brick 10.70.46.63:/rhs/brick2/cold-d2r11    49159     0          Y       30149
Brick 10.70.46.64:/rhs/brick2/cold-d1r21    49159     0          Y       23716
Brick 10.70.46.59:/rhs/brick2/cold-d1r11    49159     0          Y       19532
Cold Bricks:
Brick 10.70.46.59:/rhs/brick1/d1r11         49158     0          Y       19412
Brick 10.70.46.64:/rhs/brick1/d1r21         49158     0          Y       23610
Brick 10.70.46.63:/rhs/brick1/d2r11         49158     0          Y       30053
Brick 10.70.46.60:/rhs/brick1/d2r21         49157     0          Y       16026
 
Task Status of Volume vol2
------------------------------------------------------------------------------
Task                 : Tier migration      
ID                   : 1dd3374a-f0d5-4aa0-8a79-c1a2776ed72e
Status               : in progress         



Expected results:
no coredump expected

Additional info:
Not very which test in the test-suite caused the issue