Re: [LSF/MM ATTEND] Attendance request

[Liu Bo <bo.li.liu@oracle.com>]

On Fri, Mar 04, 2016 at 06:25:14PM +0100, David Sterba wrote:
> On Fri, Mar 04, 2016 at 08:59:06AM -0800, Liu Bo wrote:
> > On Fri, Mar 04, 2016 at 08:53:15AM -0800, Liu Bo wrote:
> > > On Fri, Mar 04, 2016 at 03:30:58PM +0100, David Sterba wrote:
> > > > On Sun, Feb 28, 2016 at 03:16:15PM -0800, Liu Bo wrote:
> > > > > Hi,
> > > > > 
> > > > > I'd like to attend the LSF/MM conference this year.
> > > > > 
> > > > > I think I can contribute to a few areas that are being discussed this year:
> > > > >   - how to provide better information for the filesystem to optimize allocation.
> > > > >   - power/failure tests
> > > > >   - performance aspects, etc.
> > > > > 
> > > > > Besides that, I'd like to talk about the following,
> > > > >   - combining overlayfs with btrfs to properly fix overlayfs copy-up slowness.
> > > > >   - fragmentation control in Copy-On-Write filesystems. (setting a reasonable
> > > > >     large allocation unit and performing RMW, etc?)
> > > > >     Since xfs is also going to have reflink, so xfs is also regarded as COW
> > > > >     FS, having some generic ideas for this topic would help a lot.
> > > > >   - mount individual subvolumes (in btrfs) with different selinux label, this
> > > > >     will be useful in container senarios when btrfs being their storage driver.
> > > > > 
> > > > > (I've finished the patch for the above selinux label support, but it can ends up
> > > > > with inode leak if it's not used in the container way, which is assuming the
> > > > > top subvolume is always being the last one to unmout.)
> > > > 
> > > > Do you have the patchset so I can have a look? I've claimed the
> > > > per-subvolume mount properties in the past and have it almost working.
> > > > Supporting selinux labels seems to have some overlap, so I'm curious how
> > > > much code conflicts are there.
> > > 
> > > There might be some conflicts since I'm using pseudo superblock for each
> > > subvolume in that case in order to support selinux label.
> > 
> > I also changed docker's btrfs graphdriver code to mount a
> > subvolume/snapshot like what devicemapper does so that it can have
> > different selinux label for each container.
> > 
> > To test it, we have to use "mount -osubvolid=AAA,nosharecache=AAA /disk /mnt"
> 
> Thanks. Code-wise there are no conflicts but my implementation does not
> expect existence of the extra superblocks so it would not work together.

Hmm..I made it only affecting inode, but as we already use different inode
namespace for each subvolume and in fact we're using pseudo superblock
in order to manage multiple disk, I think it'd be fine to use any
per-subvolume properties.

Thanks,

-liubo