[#LU-6705] MDT hung at umount under DNE mode

Just discussed with Fan Yong, it seems umount thread is blocked because it can not stop the recovery update thread. And the recovery update thread is trying to retrieve the update records from the remote MDT. and that MDT has been shutdown.

[<ffffffffa0526c18>] ? ptlrpc_set_wait+0x188/0x900 [ptlrpc]
 [<ffffffffa051c5b0>] ? ptlrpc_interrupted_set+0x0/0x110 [ptlrpc]
 [<ffffffffa051da74>] ? ptlrpc_request_pack+0x24/0x70 [ptlrpc]
 [<ffffffffa0527411>] ? ptlrpc_queue_wait+0x81/0x220 [ptlrpc]
 [<ffffffffa073655b>] ? fld_client_rpc+0x15b/0x510 [fld]
 [<ffffffffa073c42e>] ? fld_server_lookup+0x14e/0x330 [fld]
 [<ffffffffa0c804ff>] ? lod_fld_lookup+0x34f/0x520 [lod]
 [<ffffffff8116fef2>] ? kmem_cache_alloc+0x182/0x190
 [<ffffffffa0c958e3>] ? lod_object_init+0x103/0x3c0 [lod]
 [<ffffffffa1294298>] ? lu_object_alloc+0xd8/0x320 [obdclass]
 [<ffffffffa12957a1>] ? lu_object_find_try+0x151/0x260 [obdclass]
 [<ffffffffa1295961>] ? lu_object_find_at+0xb1/0xe0 [obdclass]
 [<ffffffffa0d06fc2>] ? dt_update_request_destroy+0x1c2/0x270 [osp]
 [<ffffffffa1296ebc>] ? dt_locate_at+0x1c/0xa0 [obdclass]
 [<ffffffffa125346f>] ? llog_osd_open+0xdf/0xde0 [obdclass]
 [<ffffffffa124a375>] ? llog_open+0x145/0x470 [obdclass]
 [<ffffffffa0caa82e>] ? lod_sub_prep_llog+0x19e/0x7a0 [lod]
 [<ffffffffa0c8088e>] ? lod_sub_recovery_thread+0x1be/0x980 [lod]
 [<ffffffff81061c62>] ? default_wake_function+0x12/0x20
 [<ffffffffa0c806d0>] ? lod_sub_recovery_thread+0x0/0x980 [lod]
 [<ffffffff8109ab46>] ? kthread+0x96/0xa0
 [<ffffffff8100c20a>] ? child_rip+0xa/0x20
 [<ffffffff8109aab0>] ? kthread+0x0/0xa0
 [<ffffffff8100c200>] ? child_rip+0x0/0x20

static void mdt_fini()
{
.....
       target_recovery_fini(obd);
        ping_evictor_stop();
        mdt_stack_pre_fini(env, m, md2lu_dev(m->mdt_child));
......

Simply, if we move mdt_stack_pre_fini before target_recovery_fini, the problem should go away, but that will cause other problem.

[LU-6705] MDT hung at umount under DNE mode Created: 10/Jun/15 Updated: 14/Jul/15 Resolved: 14/Jul/15
Status:	Resolved
Project:	Lustre
Component/s:	None
Affects Version/s:	Lustre 2.8.0
Fix Version/s:	Lustre 2.8.0

[LU-6705] MDT hung at umount under DNE mode Created: 10/Jun/15 Updated: 14/Jul/15 Resolved: 14/Jul/15