nfsd4: fix lockowner matching

Lockowners are looked up by file as well as by owner, but we were
forgetting to do a comparison on the file.  This could cause an
incorrect result from lockt.

(Note looking up the inode from the lockowner is pretty awkward here.
The data structures need fixing.)

Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -3809,16 +3809,29 @@ nevermind:
 		deny->ld_type = NFS4_WRITE_LT;
 }
 
+static bool same_lockowner_ino(struct nfs4_lockowner *lo, struct inode *inode, clientid_t *clid, struct xdr_netobj *owner)
+{
+	struct nfs4_ol_stateid *lst;
+
+	if (!same_owner_str(&lo->lo_owner, owner, clid))
+		return false;
+	lst = list_first_entry(&lo->lo_owner.so_stateids,
+			       struct nfs4_ol_stateid, st_perstateowner);
+	return lst->st_file->fi_inode == inode;
+}
+
 static struct nfs4_lockowner *
 find_lockowner_str(struct inode *inode, clientid_t *clid,
 		struct xdr_netobj *owner)
 {
 	unsigned int hashval = lock_ownerstr_hashval(inode, clid->cl_id, owner);
+	struct nfs4_lockowner *lo;
 	struct nfs4_stateowner *op;
 
 	list_for_each_entry(op, &lock_ownerstr_hashtbl[hashval], so_strhash) {
-		if (same_owner_str(op, owner, clid))
-			return lockowner(op);
+		lo = lockowner(op);
+		if (same_lockowner_ino(lo, inode, clid, owner))
+			return lo;
 	}
 	return NULL;
 }