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

[Chris Mason <clm@fb.com>]

Quoting David Sterba (2013-12-09 18:32:45)
> On Mon, Dec 02, 2013 at 05:02:49PM +0800, Wang Shilong wrote:
> > >So an enahced interface could look like this:
> > >
> > >subvol delete:
> > >--commit-each - run the ioc sync/wait ioctl after each delete ioctl
> > >--commit-after - dtto but sync/wait after all are deleted
> > >--wait-for-cleanup - wait until all given subvols are cleaned
> > >
> > >'filesystem sync' exteded to wait for subvol cleanup has following
> > >cases:
> > >- wait for a specific subvolume to be cleaned

It may be hard to wait for a specific subvolume from btrfs fi sync.
You'd have to know the id, or have an interface that shows a list of ids
currently under deletion (not a bad idea ;)

> > >- wait for all currently deleted, do not care if more subvols are
> > >   deleted in the meantime
> > >- wait until there are no subvolumes left to clean
> > I think it is unnecessary to add such options for 'filesystem sync'.
> > we may wait a long time until all subvolume deletion are finished as
> > async subvolume deletion is implemented in cleaner thread.:-)
> 
> I mean that 'filesystem sync' will stay as it is now, but will be
> enhanced with a few options to further specify what else should be
> synced.

It's more natural to have the waiting in the subvol delete command, but
I'm not against adding a few ways to wait in btrfs fi sync too, as long
as they share the same core implementation.

-chris