NFS: Don't gratuitously clear the inode cache when lookup failed

The fact that the lookup revalidation failed, does not mean that the
inode contents have changed.

Fixes: 5ceb9d7 ("NFS: Refactor nfs_lookup_revalidate()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Author: Trond Myklebust

fs/nfs/dir.c

@@ -1444,18 +1444,14 @@ nfs_lookup_revalidate_done(struct inode *dir, struct dentry *dentry,
 			__func__, dentry);
 		return 1;
 	case 0:
-		if (inode && S_ISDIR(inode->i_mode)) {
-			/* Purge readdir caches. */
-			nfs_zap_caches(inode);
-			/*
-			 * We can't d_drop the root of a disconnected tree:
-			 * its d_hash is on the s_anon list and d_drop() would hide
-			 * it from shrink_dcache_for_unmount(), leading to busy
-			 * inodes on unmount and further oopses.
-			 */
-			if (IS_ROOT(dentry))
-				return 1;
-		}
+		/*
+		 * We can't d_drop the root of a disconnected tree:
+		 * its d_hash is on the s_anon list and d_drop() would hide
+		 * it from shrink_dcache_for_unmount(), leading to busy
+		 * inodes on unmount and further oopses.
+		 */
+		if (inode && IS_ROOT(dentry))
+			return 1;
 		dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is invalid\n",
 				__func__, dentry);
 		return 0;