If a directory entry refers to an inode which doesn't actually exist,
we weren't marking it obsolete, so it was still visible in the file
system, and would give EIO if you ever tried to stat it. Once upon
a time, perl -e 'unlink' and rm -f would manage to unlink such things
but nowadays they both try to stat it first and stupidly refuse to 
even attempt the unlink if the stat fails, and this is more of a 
problem. So we throw it away ourselves. 
Signed-off-by: Artem Bityuckiy <dedekind@infradead.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>