LU-1812 osd-ldiskfs: oti_obj_dentry needs d_sb set

LU-1812 osd-ldiskfs: oti_obj_dentry needs d_sb set

Commit 431547b3 (v2.6.33) changed the generic xattr handlers to
use dentry->d_sb rather than dentry->d_inode->i_sb.

This patch ensures it's set before calling the xattr ops, which filter
through the generic xattr handlers.

Really, since any call into the kernel using a dentry can deref d_sb,
it should be set so we'll set it for fsync as well.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: I0ce38970cd839a220f852f96632b473011adbdc6
Reviewed-on: http://review.whamcloud.com/5120
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>