+static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
+ struct dentry *dentry, struct svc_export *exp)
+{
+ if (!(exp->ex_flags & NFSEXP_V4ROOT))
+ return nfs_ok;
+ /*
+ * v2/v3 clients have no need for the V4ROOT export--they use
+ * the mount protocl instead; also, further V4ROOT checks may be
+ * in v4-specific code, in which case v2/v3 clients could bypass
+ * them.
+ */
+ if (!nfsd_v4client(rqstp))
+ return nfserr_stale;
+ /*
+ * We're exposing only the directories and symlinks that have to be
+ * traversed on the way to real exports:
+ */
+ if (unlikely(!S_ISDIR(dentry->d_inode->i_mode) &&
+ !S_ISLNK(dentry->d_inode->i_mode)))
+ return nfserr_stale;
+ /*
+ * A pseudoroot export gives permission to access only one
+ * single directory; the kernel has to make another upcall
+ * before granting access to anything else under it:
+ */
+ if (unlikely(dentry != exp->ex_path.dentry))
+ return nfserr_stale;
+ return nfs_ok;
+}
+