qibfs: fix dentry leak

In the Linux kernel, the following vulnerability has been resolved: qibfs: fix dentry leak simple_recursive_removal() drops the pinning references to all positives in subtree. For the cases when its argument has been kept alive by the pinning alone that's exactly the right thing to do, but here the argument comes from dcache lookup, that needs to be balanced by explicit dput(). Fucked-up-by: Al Viro <viro@zeniv.linux.org.uk>