[PATCH v3] Btrfs: add regression test for running snapshot and send concurrently

[Wang Shilong]

Hi Dave,

> On Fri, Feb 07, 2014 at 12:10:08AM +0800, Wang Shilong wrote:
>> +$BTRFS_UTIL_PROG subvolume snapshot -r $SCRATCH_MNT \
>> +	$SCRATCH_MNT/snap_1 >> $seqres.full 2>&1
>> +
>> +do_snapshots &
>> +snapshots_pid=$!
>> +
>> +$BTRFS_UTIL_PROG send $SCRATCH_MNT/snap_1 > /dev/null 2>&1 || echo "btrfs send failed"
> 
> Let's stop this anti-pattern before it takes hold.
> 
> If there's output from the send command it should be
> filtered and captured in the golden image. Hence any deviation
> caused by errors is automatically flagged as an error.
> 
> That's the whole point of using golden images for capturing errors -
> you don't need to capture return values from binaries and it
> guarantees that users are informed about failures through error
> messages. IOWs:
> 
> $BTRFS_UTIL_PROG send $SCRATCH_MNT/snap_1 | _btrfs_send_filter
> 
> is what you should be doing here.

I knew what you mean here, in fact, i did this on purpose.
for this test failure, btrfs-prog did not output failure information from the beginning.
So to make older progs can also detect the test failure, i dropped into this way.

Anyway, if you don't like this and think  old btrfs-progs needn't consider this,  i will update
the patch.^_^

Thanks,
Wang

> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david at fromorbit.com