[dm-devel] Unable to deactivate lv, pehaps due to semaphore problem...

[Gianluca Cecchi]

Hello,
I'm unable to deactivate an lvm.

My system is RHEL 6.5 with lvm2-2.02.100-8.el6.x86_64 and kernel
2.6.32-431.29.2.el6.x86_64

I get error code 5 with message
  Logical volume VG_AAA_TEMP/LV_AAA_TEMP in use.

You can find output of
lvchange -d -d -d -d -d -d -an VG_AAA_TEMP/LV_AAA_TEMP
here:
https://drive.google.com/file/d/0BwoPbcrMv8mvTjlBMkRUbG9nczA/view?usp=sharing

Recreating sources from the related src.rpm the problem (as stated anyway
in error message too) is in code

activate/activate.c:711   Logical volume in use

that is
        while (open_count_check_retries--) {
                if (info->open_count > 0) {
                        if (open_count_check_retries) {
                                usleep(OPEN_COUNT_CHECK_USLEEP_DELAY);
                                log_debug_activation("Retrying open_count
check for %s/%s.",
                                                     lv->vg->name,
lv->name);
                                if (!lv_info(cmd, lv, 0, info, 1, 0))
                                        return -1;
                                continue;
                        }
                        log_error("Logical volume %s/%s in use.",
                                  lv->vg->name, lv->name);
                        return 0;
                } else
                        break;
        }

In fact I get this information querying device:

[root at orapr2 activate]# dmsetup info --checks
360a9800037543544465d424130533177
Name:              360a9800037543544465d424130533177
State:             ACTIVE
Read Ahead:        256
Tables present:    LIVE
Open count:        1
Event number:      23
Major, minor:      253, 4
Number of targets: 1
UUID: mpath-360a9800037543544465d424130533177

[root at orapr2 activate]# dmsetup table 360a9800037543544465d424130533177
0 2097152 multipath 4 queue_if_no_path pg_init_retries 50
retain_attached_hw_handler 1 alua 2 1 round-robin 0 4 1 66:160 1 69:192 1
133:224 1 8:288 1 round-robin 0 4 1 8:96 1 68:48 1 129:32 1 130:128 1

I got in past days a problem related to sempahores
(maximum number of semaphore sets has been exceeded)
and I suspect that some resource could have been incorrectly locked.

The device is sort of
  [root at orapr2 ~]# multipath -l  360a9800037543544465d424130533177
360a9800037543544465d424130533177 dm-4 NETAPP,LUN
size=1.0G features='4 queue_if_no_path pg_init_retries 50
retain_attached_hw_handle' hwhandler='1 alua' wp=rw
|-+- policy='round-robin 0' prio=0 status=active
| |- 1:0:1:7  sdaq 66:160  active undef  running
| |- 1:0:2:7  sdco 69:192  active undef  running
| |- 2:0:2:7  sdho 133:224 active undef  running
| `- 2:0:3:7  sdiy 8:288   active undef  running
`-+- policy='round-robin 0' prio=0 status=enabled
  |- 1:0:0:7  sdg  8:96    active undef  running
  |- 2:0:0:7  sdbp 68:48   active undef  running
  |- 1:0:3:7  sdeq 129:32  active undef  running
  `- 2:0:1:7  sdfm 130:128 active undef  running

and the filesystem on it has been successfully umounted, but

[root at orapr2 ~]# lvs VG_AAA_TEMP/LV_AAA_TEMP
  LV          VG          Attr       LSize    Pool Origin Data%  Move Log
Cpy%Sync Convert
  LV_AAA_TEMP VG_AAA_TEMP -wi-ao---- 1020.00m

How can I see the responsible for the reference that apparently keeps it
open?

Open count:        1
so I can check and eventually fix??

Thanks in advance.

Gianluca
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