[Btrfs-devel] Next things to work on

[Toei Rei]

On Wednesday 15 August 2007 03:22:51 Josef Bacik wrote:
> On Tue, Aug 14, 2007 at 08:23:29PM -0400, Chris Mason wrote:
> > On Tue, 14 Aug 2007 11:44:37 -0400
> >
> > Josef Bacik <jbacik at redhat.com> wrote:
> > > Hello,
> > >
> > > I assume the block stuff I sent is OK so I'm going to start working
> > > on xattrs, unless there are any objections?  Want to make sure since
> > > I have a tendancy to step on your toes Chris :).
> >
> > Hi, sorry for the delay.  The top of my list right now is real tree
> > locking, so xattrs won't cause too many problems.  Your accounting
> > stuff looks pretty good to me, but we need some btrfsctl command or
> > sysfs code (sysfs would be better) to spit out information about
> > usage/quotas.
> >
> > Xattrs are a fairly good sized chunk of work, as long as you don't mind
> > having to go through a few iterations I'd be thrilled to see someone do
> > it.
> >
> > Basically I would start with small xattrs that fit inside a tree
> > block.  The idea is to put these small xattrs inside directory
> > items (similar to how we pack file bodies inside extents).  But, you'll
> > need a new key type because directories already have directory items.
> > In ctree.h you'll find:
> >
> > #define BTRFS_INODE_ITEM_KEY            1
> >
> > /* reserve 2-15 close to the inode for later flexibility */
> >
> > We want the xattrs right after the inode on disk, so use key type 2.
> >
> > You'll have to refactor the directory code a little so you can reuse it
> > to store the xattrs.  directory items have a flags field and a type
> > field.  The type field stores things used by readdir, but the flags
> > field is currently unused.
> >
> > For large xattrs the dir items would point to a key, which is just a
> > regularly allocated inode.  But you can get there later.
>
> Well that is a nice helping of work.  I'll go ahead and add the sysfs code
> for the block accounting stuff so you don't have a half-assed solution, and
> provided you don't have anything else more pressing you'd like me to work
> on I'll move on to xattrs.  I don't mind  having to go through a few
> interations, it took me 5 just for the fsync stuff :).  Thanks much,
>
> Josef
>
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Sounds quite nice - but would it be possible to spill out a message as the 
module is loaded stating the version of the module  you're loading as it 
makes it easier for me testing...

-- 
mfg

Toei Rei
STARGAZER systems

http://www.stargazer.at
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