NFS: Fix nfs_reval_fsid()

We don't need to revalidate the fsid on the root directory. It suffices to
revalidate it on the current directory.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/dir.c

@@ -897,14 +897,13 @@ int nfs_is_exclusive_create(struct inode *dir, struct nameidata *nd)
 	return (nd->intent.open.flags & O_EXCL) != 0;
 }
 
-static inline int nfs_reval_fsid(struct vfsmount *mnt, struct inode *dir,
-				 struct nfs_fh *fh, struct nfs_fattr *fattr)
+static inline int nfs_reval_fsid(struct inode *dir, const struct nfs_fattr *fattr)
 {
 	struct nfs_server *server = NFS_SERVER(dir);
 
 	if (!nfs_fsid_equal(&server->fsid, &fattr->fsid))
-		/* Revalidate fsid on root dir */
-		return __nfs_revalidate_inode(server, mnt->mnt_root->d_inode);
+		/* Revalidate fsid using the parent directory */
+		return __nfs_revalidate_inode(server, dir);
 	return 0;
 }
 
@@ -946,7 +945,7 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, stru
 		res = ERR_PTR(error);
 		goto out_unlock;
 	}
-	error = nfs_reval_fsid(nd->mnt, dir, &fhandle, &fattr);
+	error = nfs_reval_fsid(dir, &fattr);
 	if (error < 0) {
 		res = ERR_PTR(error);
 		goto out_unlock;

fs/nfs/inode.c

@@ -961,8 +961,8 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 		goto out_changed;
 
 	server = NFS_SERVER(inode);
-	/* Update the fsid if and only if this is the root directory */
-	if (inode == inode->i_sb->s_root->d_inode
+	/* Update the fsid? */
+	if (S_ISDIR(inode->i_mode)
 			&& !nfs_fsid_equal(&server->fsid, &fattr->fsid))
 		server->fsid = fattr->fsid;