[Btrfs-devel] Anyone working on xattr support?

[Chris Mason]

On Tue, 31 Jul 2007 15:29:01 -0700
Zach Brown <zab at zabbo.net> wrote:

> > For the large xattr case, it would actually point to an inode that
> > would work just like a normal file.
> 
> This makes me nervous, maybe we should talk about this point in more
> detail.  I don't like the idea of bringing all the per-file posix api
> nonsense in the inode (i_uid, i_mode, etc) just so that xattrs can
> store data.

Well, its a trade off between ~100 bytes of inode for a large xattr,
along with (hopefully) lots of code reuse vs something more specialized.

> 
> I guess I'm hoping for structures with a finer granularity than that.
> 
> I care because of the unfun time I had with fsck.ocfs2.  It has to
> jump through hoops to figure out when certain fields in an inode
> could be ignored or not based on what that internal
> "inode" (sometimes only a few fields!) was really being used for.

The directory item will be able to store almost a full block worth
(minus 200 bytes or so of header, the other goo and the xattr name).
So, the large ones are a corner case that will be rarely used.  I'd
like them to be as simple as possible.  Every xattr inode would have a
flag set that says I'm an xattr inode!, and it shouldn't be all that
hard on fsck.

-chris