Re: [RFC][PATCH] btrfs: add ioctl to monitor subvolume dropping

[Mark Fasheh <mfasheh@suse.de>]

On Tue, Oct 06, 2015 at 10:09:26AM -0700, Mark Fasheh wrote:
> On Tue, Oct 06, 2015 at 10:25:52AM +0200, David Sterba wrote:
> > On Thu, Oct 01, 2015 at 02:30:47PM -0700, Mark Fasheh wrote:
> > > At the moment, userspace has no way of knowing when a snapshot is finally
> > > removed. This has become a problem when writing tests for btrfs,
> > > 
> > > http://article.gmane.org/gmane.comp.file-systems.fstests/1239/
> > 
> > In the meantime the command 'btrfs subvolume sync /path id' has been
> > implemented which does what you need, without the new ioctl.
> 
> Ahh ok I didn't see that I'll take a look, thanks.

Hmm this isn't working for me, am I doing anything wrong? 

mkfs.btrfs -f  /dev/vdb1 
mount -t btrfs /dev/vdb1 /btrfs/
cd /btrfs/
btrfs quota enable /btrfs
btrfs su create sub1
cp -a /boot/* sub1/
btrfs su create sub2
cp -a /boot/* sub2
btrfs su de sub1 -c
btrfs su sy /btrfs/
cd /
umount /btrfs 
btrfsck --qgroup-report /dev/vdb1

The output of btrfsck (and btrfs-debug-tree) will show the subvolume still
existing on disk. I tried '-c' and '-C' with the 'btrfs su de' command and
neither made a difference.

This is on btrfs-progs v4.2.2+20151005.

Thanks,
	--Mark

--
Mark Fasheh