scub neither running nor canceling nor can be restarted.

[Vikram Goyal <vikram@smcindiaonline.com>]

Hello,

I am having a problem where a stuck scrub on root FS cannot be
cancelled or restsrted.

Please See:
[root@mail2 ~]# btrfs filesystem show
Label: fedora_mail2  uuid: d2b3420c-99c1-44cc-a922-ac266072c7fb
Total devices 2 FS bytes used 58.88GiB
devid    2 size 73.51GiB used 31.03GiB path /dev/sdb6
devid    3 size 73.30GiB used 32.03GiB path /dev/sda2

Label: Vikram  uuid: 0809b072-35f3-4866-92b8-af4772b23ed6
Total devices 2 FS bytes used 98.05GiB
devid    1 size 158.03GiB used 99.04GiB path /dev/mapper/sda3
devid    2 size 157.00GiB used 99.03GiB path /dev/dm-1

Btrfs v3.12
[root@mail2 ~]# btrfs scrub status -d /
scrub status for d2b3420c-99c1-44cc-a922-ac266072c7fb
scrub device /dev/sdb6 (id 2) status
scrub started at Thu Apr 18 13:51:13 2013, running for 105 seconds
total bytes scrubbed: 3.81GiB with 0 errors
scrub device /dev/sda2 (id 3) status
scrub started at Thu Apr 18 13:51:13 2013, running for 105 seconds
total bytes scrubbed: 4.34GiB with 0 errors

[root@mail2 ~]# btrfs scrub cancel /
ERROR: scrub cancel failed on /: not running

[root@mail2 ~]# btrfs scrub start -Bd /
ERROR: scrub is already running.
To cancel use 'btrfs scrub cancel /'.
To see the status use 'btrfs scrub status [-d] /'.

Thanks!
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