[PATCH] Reduce number of LOOKUP calls in nfs_lookup_revalidate()

fs/nfs/inode.c:
  - Ensure that we initialize NFS_MTIME_UPDATE(inode).

  - If a directory's mtime changed due to some action on our part
    (file creation/deletion/...) don't force a dcache revalidation by
    changing NFS_MTIME_UPDATE(inode).

fs/nfs/inode.c

@@ -693,6 +693,7 @@ __nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
 		inode->i_atime = new_atime;
 		NFS_CACHE_MTIME(inode) = new_mtime;
 		inode->i_mtime = nfs_time_to_secs(new_mtime);
+		NFS_MTIME_UPDATE(inode) = jiffies;
 		NFS_CACHE_ISIZE(inode) = new_size;
 		inode->i_size = new_isize;
 		inode->i_mode = fattr->mode;
@@ -1058,7 +1059,8 @@ __nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
 	inode->i_atime = new_atime;
 
 	if (NFS_CACHE_MTIME(inode) != new_mtime) {
-		NFS_MTIME_UPDATE(inode) = jiffies;
+		if (invalid)
+			NFS_MTIME_UPDATE(inode) = jiffies;
 		NFS_CACHE_MTIME(inode) = new_mtime;
 		inode->i_mtime = nfs_time_to_secs(new_mtime);
 	}