Created attachment 893229 [details]
gdb backtrace

Description of problem:
--------------------------

glusterfsd processes of a distributed-replicate volume crashed after quota was enabled on a volume on which it had been enabled and disabled previously.

The following was seen when the core was examined with gdb -
-------------------------------------------------------------------------------

(gdb) p *rpc->conn.rpc_clnt
$4 = {lock = {__data = {__lock = 0, __count = 0, __owner = 0, __nusers = 0, __kind = 0, __spins = 0, __list = {__prev = 0x0, __next = 0x0}}, 
    __size = '\000' <repeats 39 times>, __align = 0}, notifyfn = 0x7f34b77c2690 <quota_enforcer_notify>, conn = {lock = {__data = {__lock = 0, __count = 0, 
        __owner = 0, __nusers = 0, __kind = 0, __spins = 0, __list = {__prev = 0x0, __next = 0x0}}, __size = '\000' <repeats 39 times>, __align = 0}, trans = 0x0, 
    config = {rpc_timeout = 0, remote_port = 0, remote_host = 0x0}, reconnect = 0x0, timer = 0x0, ping_timer = 0x0, rpc_clnt = 0x2344ef0, connected = 0 '\000', 
    saved_frames = 0x233ecc0, frame_timeout = 1800, last_sent = {tv_sec = 1399457050, tv_usec = 294940}, last_received = {tv_sec = 1399456455, tv_usec = 40203}, 
    ping_started = 0, name = 0x233c240 "dis_rep_vol-quota"}, mydata = 0x22ebd60, xid = 160030, programs = {next = 0x2344fd8, prev = 0x2344fd8}, reqpool = 0x233c1c0, 
  saved_frames_pool = 0x2347520, ctx = 0x22ab010, refcount = 1, auth_null = 0, disabled = 1 '\001'}

Note that 'trans' is seen as null above.

Find attached the gdb backtrace.

Version-Release number of selected component (if applicable):
glusterfs-3.5qa2-0.369.git500a656.el6rhs.x86_64

How reproducible:
Saw it once in my setup.

Steps to Reproduce:
1. Enable quota on a distributed-replicate volume and set the limit. The volume is mounted on a client and data written to cross the soft limit set on a particular directory.
2. Quota is disabled after a while.
3. Enabled quota again after a while.

Actual results:
Brick processes crashed.

Expected results:
Brick processes should not crash.

Additional info: