memlock_inc increased device open count problem

[niko <tongfw@gmail.com>]

Hi,everyone

I'm using mpatocka's patches for shared snapshot on RHEL6.

Problem occurred when creating shared cow storage volume.

the same problem occurred when creating snapshot

I got error message:

 

  Unable to deactivate open vgtest-orig--shared (253:2)
  Aborting. Couldn't deactivate snapshot COW area. Manual intervention required.

Then,I did some digging, in lv_deactivate

 

@@ -1117,6 +1121,9 @@
                stack;

        memlock_inc(cmd);
+       if (!lv_info(cmd, lv, 0, &info, 1, 0))
+               goto_out;
+       log_verbose("lv_deactivate: open_count %d", info.open_count);
        r = _lv_deactivate(lv);
        memlock_dec(cmd);
        fs_unlock();

it turns out :

 

 lv_deactivate: open_count 1

before memlock_inc, open_count is 0

 

I wonder how it changes to 1 ?

--
niko

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