NFSv4: Some NFSv4 servers have broken behaviour for the change attribute

The Linux NFSv4 server violates RFC3530 in that the change attribute is not
guaranteed to be updated for every change to the inode. Our optimisation
for checking whether or not the inode metadata has changed or not is broken
too. Grr....
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/inode.c

@@ -1414,9 +1414,8 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat
 	/* Do atomic weak cache consistency updates */
 	nfs_wcc_update_inode(inode, fattr);
 
-	if ((fattr->valid & NFS_ATTR_FATTR_V4) != 0) {
-		if (nfsi->change_attr == fattr->change_attr)
-			goto out;
+	if ((fattr->valid & NFS_ATTR_FATTR_V4) != 0 &&
+			nfsi->change_attr != fattr->change_attr) {
 		nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
 		if (!data_unstable)
 			nfsi->cache_validity |= NFS_INO_REVAL_PAGECACHE;
@@ -1444,7 +1443,6 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat
 	if (inode->i_nlink != fattr->nlink)
 		nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
 
-out:
 	if (!timespec_equal(&inode->i_atime, &fattr->atime))
 		nfsi->cache_validity |= NFS_INO_INVALID_ATIME;
 
@@ -1612,15 +1610,13 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
  		inode->i_blksize = fattr->du.nfs2.blocksize;
  	}
 
-	if ((fattr->valid & NFS_ATTR_FATTR_V4)) {
-		if (nfsi->change_attr != fattr->change_attr) {
+	if ((fattr->valid & NFS_ATTR_FATTR_V4) != 0 &&
+			nfsi->change_attr != fattr->change_attr) {
 		dprintk("NFS: change_attr change on server for file %s/%ld\n",
 				inode->i_sb->s_id, inode->i_ino);
 		nfsi->change_attr = fattr->change_attr;
 		invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
 		nfsi->cache_change_attribute = jiffies;
-		} else
-			invalid &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA);
 	}
 
 	/* Update attrtimeo value if we're out of the unstable period */