[NFS][PATCH] Making sure negative lookup entries don't exist

[Steve Dickson <SteveD@redhat.com>]

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Here is a 2.4.28 patch that ensures negative cached dirents
do not exist by always doing an otw getattr to the server.
This does cause a small increase in getattrs (~3% from what
I saw in my testing) but it seems to me the price is worth it to
ensure the client does not lie about the existence of a file.

comments?

steved.

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--- linux-2.4.28/fs/nfs/dir.c.orig	2004-08-07 19:26:06.000000000 -0400
+++ linux-2.4.28/fs/nfs/dir.c	2005-01-28 13:00:59.402239000 -0500
@@ -455,7 +455,11 @@ int nfs_lookup_verify_inode(struct inode
  */
 static inline int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry)
 {
-	if (!nfs_check_verifier(dir, dentry))
+	if (IS_ROOT(dentry))
+		return 1;
+	if (__nfs_revalidate_inode(NFS_SERVER(dir), dir))
+		return 1;
+	if (time_after(NFS_MTIME_UPDATE(dir), dentry->d_time))
 		return 1;
 	return time_after(jiffies, dentry->d_time + NFS_ATTRTIMEO(dir));
 }