There are a couple of places where JBD has to check to see whether an unneeded
memory allocation was performed. Usually it _was_ needed, so we end up
calling kfree(NULL). We can micro-optimise that by checking the pointer
before calling kfree().
Thanks to Steven Rostedt <rostedt@goodmis.org> for identifying this.
Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>