xfs: replay unlocked parent pointer updates that accrue during xattr repair

xfs: replay unlocked parent pointer updates that accrue during xattr repair

There are a few places where the extended attribute repair code drops
the ILOCK to apply stashed xattrs to the temporary file.  Although
setxattr and removexattr are still locked out because we retain our hold
on the IOLOCK, this doesn't prevent renames from updating parent
pointers, because the VFS doesn't take i_rwsem on children that are
being moved.

Therefore, set up a dirent hook to capture parent pointer updates for
this file, and replay(?) the updates.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>