Re: 3.13.5 kernel hangs some processes with btrfs

[Wang Shilong <wangsl.fnst@cn.fujitsu.com>]

On 02/24/2014 02:58 PM, Marc MERLIN wrote:
> On Mon, Feb 24, 2014 at 06:42:30AM +0000, Duncan wrote:
>> I believe there's a fix coming (a cancel that blows away the tracking
>> file if it finds it and no actual running scrub is the most obvious fix),
>> but meanwhile, see the /var/lib/btrfs/scrub.status.* files.  That's where
>> scrub state is stored, and manually blowing away the appropriate file
>> should clear btrfs' memory of the aborted scrub, so you can scrub start
>> properly.
> Ah, silly me, I thought this was all in the kernel and not in userspace.
>
> Yep, I cleared the stats, and that part is back to ok, thanks.
>
> I'm not getting btrfs hang on /mnt/btrfs_pool2 after reboot, so that's good.
>
> But I'm still seeing these, albeit less often.
> Any idea what they could be linked to?
> (I have a btrs send/receive going right now, it could hanging /mnt/btrfs_pool1

I noticed  scrub for /mnt/btrfs_pool1 is running more than 10000s....

Not sure if it is related to send/receive, but if you are still runing 
send/receive,
just terminate it and let's see if things will become better.

Also Josef gave a patch that can speed up send/receive a lot which has been
pused into btrfs-next, you can try it.

Thanks,
Wang
> in a way that affects smbd, but the array feels ok otherwise, weird...)
>