Re: [PATCH] btrfs-progs: add options to sync filesystem after subvol delete

[David Sterba <dsterba@suse.cz>]

On Tue, Dec 10, 2013 at 01:24:13PM -0500, Chris Mason wrote:
> > It is there, 'btrfs subvol list -d /path', but I'd rather not let
> > everybody parse output the output for a simple check.
> 
> Aha ;) Yeah, that's what I was thinking.  It's possible to find but hard
> enough that nobody would be happy using it.

Sorry I dont' udnerstand, you mean that the -d option is hard to find?

> > Yeah it's natural and I guess it'll be the most frequent type of use.
> > I've tried to think of the possible uses so we don't miss anything
> > during design phase.
> > 
> > Knowing the ID is necessary, the subvolume path is lost at deletion
> > time, but let's say that the ID is available somehow, eg from
> > application logs.
> > 
> > I have a prototype for that, there's a separate subcommand to do just
> > the waiting for a given subvolume list id to be cleaned up (but could
> > be merged to fi sync if desired). It's built around the SEARCH ioctl and
> > does not need kernel support.
> 
> So the part where I think we agree is I don't think the kernel subvol
> deletion ioctl should do the waiting.

Yes, I've abandoned the kernel approach, for several reasons.

> Exactly how the progs wait is a different question.

BTRFS_IOC_START_SYNC + BTRFS_IOC_WAIT_SYNC

I'll send out v2.