Note that the race also exists between 2 nfs client, one of them doing the rm.
In ufs_ihashget(), vget() can return a vnode that has been vclean'ed because
vget() can sleep. After vget returns, check that vp is still connected with
ip, and that ip still points to the inode we want. This fix the NULL
pointer dereference in ufs_fhtovp() I've been seeing on a NFS server.
XXX I have no idea why using vput() instead of
vlockmgr(vp->v_vnlock, LK_RELEASE); vrele(vp); does not work.
7de71fb523