0d0d1107 asserts that "d_splice_alias()
can't return error unless it was given an IS_ERR(inode)".

That was true of the implementation of d_splice_alias, but this is
really a problem with d_splice_alias: at a minimum it should be able to
return -ELOOP in the case where inserting the given dentry would cause a
directory loop.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>