Re: (un)mounting takes a long time

[Josef Bacik <jbacik@fusionio.com>]

On Sun, Aug 11, 2013 at 03:44:10PM +0200, Florian Lindner wrote:
> Hello!
> 
> I'm using ArchLinux with kernel Linux horus 3.10.5-1-ARCH #1 SMP PREEMPT. 
> Mounting and unmounting takes a long time:
> 
> # time mount -v /mnt/Archiv         
> mount: /dev/sde1 mounted on /mnt/Archiv.
> mount -v /mnt/Archiv  0,00s user 0,16s system 1% cpu 9,493 total
> 
> # sync && time umount -v /mnt/Archiv
> umount: /mnt/Archiv (/dev/sdd1) unmounted
> umount -v /mnt/Archiv  0,00s user 0,33s system 1% cpu 23,247 total
> 
> fstab:
> 
> LABEL=Archiv    /mnt/Archiv             btrfs           defaults,compress=zlib 
> 0 0
> 
> Archiv is a RAID 0 comprised of two discs:
> 
> Label: 'Archiv'  uuid: b2504193-efeb-4ef3-8797-a8d73536a416
>         Total devices 2 FS bytes used 1.99TB
>         devid    2 size 2.73TB used 1023.01GB path /dev/sde1
>         devid    1 size 2.73TB used 1023.03GB path /dev/sdd1
> 
> Are un(mounting) times like these normal?

Are you using -o space_cache?  If not can you add that and mount/umount a couple
of times to get the cache built up and see if that helps.  If you are using
space cache then sysrq+w while its taking forever to unmount and create a
bugzilla at bugzilla.kernel.org (make sure the component is set to btrfs) so I
can take a look at it.  Thanks,

Josef