NFS: fix nfs_verify_change_attribute

We always want to check that the verifier and directory
cache_change_attribute match. This also allows us to remove the 'wraparound
hack' for the cache_change_attribute. If we're only checking for equality,
then we don't care about wraparound issues.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/inode.c

@@ -972,10 +972,6 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 	nfsi->read_cache_jiffies = fattr->time_start;
 	nfsi->last_updated = now;
 
-	/* Fix a wraparound issue with nfsi->cache_change_attribute */
-	if (time_before(now, nfsi->cache_change_attribute))
-		nfsi->cache_change_attribute = now - 600*HZ;
-
 	/* Are we racing with known updates of the metadata on the server? */
 	data_stable = nfs_verify_change_attribute(inode, fattr->time_start);
 	nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ATIME

include/linux/nfs_fs.h

@@ -277,7 +277,7 @@ static inline long nfs_save_change_attribute(struct inode *inode)
 static inline int nfs_verify_change_attribute(struct inode *inode, unsigned long chattr)
 {
 	return !nfs_caches_unstable(inode)
-		&& time_after_eq(chattr, NFS_I(inode)->cache_change_attribute);
+		&& chattr == NFS_I(inode)->cache_change_attribute;
 }
 
 /*