NFS: Separate metadata and page cache revalidation mechanisms

Separate out the function of revalidating the inode metadata, and
revalidating the mapping. The former may be called by lookup(),
and only really needs to check that permissions, ctime, etc haven't changed
whereas the latter needs only done when we want to read data from the page
cache, and may need to sync and then invalidate the mapping.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index eddd0e9..69036ef 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1220,7 +1220,7 @@
 		status = -ESTALE;
 		/* Do we trust the cached ESTALE? */
 		if (NFS_ATTRTIMEO(inode) != 0) {
-			if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ATIME)) {
+			if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME)) {
 				/* no */
 			} else
 				goto out;
@@ -1251,8 +1251,6 @@
 	}
 	spin_unlock(&inode->i_lock);
 
-	nfs_revalidate_mapping(inode, inode->i_mapping);
-
 	if (nfsi->cache_validity & NFS_INO_INVALID_ACL)
 		nfs_zap_acl_cache(inode);
 
@@ -1287,7 +1285,7 @@
 int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
 {
 	nfs_inc_stats(inode, NFSIOS_INODEREVALIDATE);
-	if (!(NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
+	if (!(NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATTR)
 			&& !nfs_attribute_timeout(inode))
 		return NFS_STALE(inode) ? -ESTALE : 0;
 	return __nfs_revalidate_inode(server, inode);
@@ -1298,9 +1296,16 @@
  * @inode - pointer to host inode
  * @mapping - pointer to mapping
  */
-void nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
+int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
+	int ret = 0;
+
+	if (NFS_STALE(inode))
+		ret = -ESTALE;
+	if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
+			|| nfs_attribute_timeout(inode))
+		ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
 
 	if (nfsi->cache_validity & NFS_INO_INVALID_DATA) {
 		nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);
@@ -1321,6 +1326,7 @@
 				inode->i_sb->s_id,
 				(long long)NFS_FILEID(inode));
 	}
+	return ret;
 }
 
 /**