clean up the attr interface

Christoph Hellwig
2019-12-12T10:54:37Z

Hi all,

while looking over the parent pointer series from Allison I found
various issues with our attr interfaces. Initially I was just
concerned about the XFS internal interface, but it turns out we
have some nasty blunders in the ioctl interface as well. This
series thus turned out a bit bigger than I hoped. The first few
patches are actual bug fixes that are 5.5 and -stable candidates.