[PATCH] NFS: Fix cache consistency races

If the data cache has been marked as potentially invalid by nfs_refresh_inode,
we should invalidate it rather than assume that changes are due to our own
activity.

Also ensure that we always start with a valid cache before declaring it
to be protected by a delegation.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index d7f7eb6..4a36839 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -85,6 +85,10 @@
 	struct nfs_delegation *delegation;
 	int status = 0;
 
+	/* Ensure we first revalidate the attributes and page cache! */
+	if ((nfsi->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_ATTR)))
+		__nfs_revalidate_inode(NFS_SERVER(inode), inode);
+
 	delegation = nfs_alloc_delegation();
 	if (delegation == NULL)
 		return -ENOMEM;