[PATCH] inotify/idr leak fix

Fix a bug which was reported and diagnosed by
Stefan Jones <stefan.jones@churchillrandoms.co.uk>

IDR trees include a cache of idr_layer objects.  There's no way to destroy
this cache, so when we discard an overall idr tree we end up leaking some
memory.

Add and use idr_destroy() for this.  v9fs and infiniband also need to use
idr_destroy() to avoid leaks.

Or, we make the cache global, like radix_tree_preload().  Which is probably
better.  Later.

Cc: Eric Van Hensbergen <ericvh@ericvh.myip.org>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/inotify.c

@@ -176,6 +176,7 @@ static inline void put_inotify_dev(struct inotify_device *dev)
 	if (atomic_dec_and_test(&dev->count)) {
 		atomic_dec(&dev->user->inotify_devs);
 		free_uid(dev->user);
+		idr_destroy(&dev->idr);
 		kfree(dev);
 	}
 }