[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: NTrond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

fs/nfs/delegation.c

@@ -85,6 +85,10 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
 	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;

fs/nfs/file.c

@@ -137,7 +137,8 @@ static int nfs_revalidate_file(struct inode *inode, struct file *filp)
 	struct nfs_inode *nfsi = NFS_I(inode);
 	int retval = 0;
 
-	if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE) || nfs_attribute_timeout(inode))
+	if ((nfsi->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_ATTR))
+			|| nfs_attribute_timeout(inode))
 		retval = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
 	nfs_revalidate_mapping(inode, filp->f_mapping);
 	return 0;

fs/nfs/inode.c

@@ -1226,10 +1226,6 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
 	loff_t cur_size, new_isize;
 	int data_unstable;
 
-	/* Do we hold a delegation? */
-	if (nfs_have_delegation(inode, FMODE_READ))
-		return 0;
-
 	spin_lock(&inode->i_lock);
 
 	/* Are we in the process of updating data on the server? */
@@ -1350,7 +1346,8 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
 	nfsi->read_cache_jiffies = fattr->timestamp;
 
 	/* Are we racing with known updates of the metadata on the server? */
-	data_unstable = ! nfs_verify_change_attribute(inode, verifier);
+	data_unstable = ! (nfs_verify_change_attribute(inode, verifier) ||
+		(nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE));
 
 	/* Check if our cached file size is stale */
  	new_isize = nfs_size_to_loff_t(fattr->size);