Re: [RFC][PATCH] Generic fallback for security xattrs

[Jeff Mahoney <jeffm@suse.de>]

Christoph Hellwig wrote:
> Very nice, and gets rid of lots of crap.  Now that we started parsing
> the attribute name in generic code we should deprecate the old
> ->{get,set,list,remove}xattr inode operations and make the helpers
> James added a while ago mandatory for the future.

I'd be fine with making the generic xattr routines the default with a
few exceptions:

1) Pass the entire name of the xattr (including prefix) to the
underlying filesystem. ReiserFS needs the entire name, including the
prefix, to look up an xattr. Reconstructing the name again, when it was
available in the caller, is wasteful. Once the determination of the
prefix is made, the filesystem code can just skip the prefix length
anyway if it doesn't need it.

2) Keep i_op->listxattr. For xattrs like system.posix_acl_access, sure,
it makes sense. But when selinux or user xattrs are introduced, the name
and number of such xattrs will be unknown to a generic routine.

I have a series of patches for reiserfs xattrs that I'm still working
the kinks out of, mainly performance-wise. With the patch set applied,
reiserfs_{set,get,remove}xattr look identical to the generic versions,
except that find_xattr_handler_prefix doesn't modify the name.

-Jeff

-- 
Jeff Mahoney
SuSE Labs