[PATCH] Makes nfs mount warning less frequent and more valuable

[David Greaves <david@dgreaves.com>]

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Neil,

This is in response to an ongoing quest to shut the kernel up when it 
whines:
   kernel: nfs warning: mount version older than kernel
incessantly and uselessly, I spoke to the am-utils people and eventually 
got some help tracking it down.

Googling around the error reveals many, many confused souls and no 
obvious reason for the message.

Ion Badulescu wrote:

> David,
>
> The basic answer is: don't worry about it, it's not harmful in any way.
>
> Until amd supports NFSv4, it will continue to cause the kernel to 
> print out this message. I've always questioned the usefulness of this 
> message, given that v2 and v3 clients (and mount programs) are fully 
> supported and will continue to be for the foreseeable future, but it 
> never bothered me enough to do something about it.

So is this the logic to produce a potentially useful warning?
patch is against 2.6.11

(This code is only executed at mount time so I assume the minor 
additional logic for a mere warning is acceptable)

It certainly makes life quieter with heavily automounted systems.


Signed-off-by: David Greaves <david@dgreaves.com>


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--- fs/nfs/inode.c.orig	2005-03-15 16:12:07.000000000 +0000
+++ fs/nfs/inode.c	2005-03-16 13:42:13.000000000 +0000
@@ -1385,9 +1385,19 @@ static struct super_block *nfs_get_sb(st
 	/* Zero out the NFS state stuff */
 	init_nfsv4_state(server);
 
+	/* NFS v2 and v3 are interoperable and will continue to be so..
+	 * This should be reviewed when NFS_MOUNT_VERSION increments */
+	if ((data->version <2 ||
+	     data->version >6 ||
+	     NFS_MOUNT_VERSION < 2 ||
+	     NFS_MOUNT_VERSION > 6)
+	    && data->version != NFS_MOUNT_VERSION) {
+		printk("nfs warning: possibly dangerous mount version incompatibility: mount(v%d) %s than kernel(v%d)\n",
+		       data->version, data->version < NFS_MOUNT_VERSION ? "older" : "newer", NFS_MOUNT_VERSION);
+	}
+	
+	/* All <> values of NFS_MOUNT_VERSION 2..6 are handled */
 	if (data->version != NFS_MOUNT_VERSION) {
-		printk("nfs warning: mount version %s than kernel\n",
-			data->version < NFS_MOUNT_VERSION ? "older" : "newer");
 		if (data->version < 2)
 			data->namlen = 0;
 		if (data->version < 3)