Re: [PATCH] common/rc: Use -v option with findmnt

[Goldwyn Rodrigues <rgoldwyn@suse.de>]

On 03/14/2017 12:07 AM, Eryu Guan wrote:
> On Mon, Mar 13, 2017 at 01:07:26PM -0500, Goldwyn Rodrigues wrote:
>> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
>>
>> Since btrfs puts in the subvol name in the device, we should
>> use -v option to not print the bind mounts or btrfs volumes.
>>
>> Fixes: 5e6892d ("common/rc: use findmnt to check mounted device")
>> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Hmm, I mounted a btrfs snapshot of TEST_DEV to another dir and ran
> check, check reported:
> 
> TEST_DEV=/dev/sdc1 is mounted but not on TEST_DIR=/mnt - aborting
> Already mounted result:
> /dev/sdc1[/snap] /mnt/scratch
> 
> which seems fine and clear to me. Did you hit any particular failures
> without this fix?


The problem is you hit this error even if /dev/sdc1 is mounted on
TEST_DIR=/mnt because of the subvolume name appended to the device name.

IOW, the test fails when it should not have. Here is an output of
executing btrfs/021:

    --- tests/btrfs/021.out	2017-01-26 02:23:04.444778259 -0600
    +++ /fiona/xfstests/results//btrfs/021.out.bad	2017-03-14
04:25:38.807212599 -0500
    @@ -1,2 +1,4 @@
     QA output created by 021
    -Silence is golden
    +SCRATCH_DEV=/dev/vdc is mounted but not on SCRATCH_MNT=/scratch -
aborting
    +Already mounted result:
    +/dev/vdc[/newvol] /scratch

However, this fix is incorrect.

I found that this was because of reminiscences of btrfs/009
Adding _scratch_umount to the end of btrfs/009 solves the issue, since
the filesystem is created fresh in the next test.

The filesystem was not created fresh in the next test because findmnt
would fail in _require_scratch.

I will shortly post a new patch which would fix this.



-- 
Goldwyn