rsc_lookup is a bit complicated: it either takes responsibility for the memory
pointed to by handle.data and sets handle.data to NULL, or it leaves
handle.data unchanged, in which case the caller is responsible for freeing
handle.data.  I forgot that the possibility of inserting a negative cache
entry into the cache meant that this could happen even when rsc_lookup is
called with set == 0.

Note that the ip_map code has the same bug, not that it seems to matter much,
since the memory in question in that case is always just a statically
allocated string.

From: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>