NFS: Correct timing for assigning access cache timestamp

When the user's login time is newer than the cache's timestamp,
the original entry in the RB-tree will be replaced by a new entry.
Currently, the timestamp is only set if the entry is not found in
the RB-tree, which can cause the timestamp to be undefined when
the entry exists. This may result in a significant increase in
ACCESS operations if the timestamp is set to zero.

Signed-off-by: Chengen Du <chengen.du@canonical.com>
Fixes: 0eb43812c027 ("NFS: Clear the file access cache upon login”)
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index a41c3ee..6fbcbb8 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -3089,7 +3089,6 @@ static void nfs_access_add_rbtree(struct inode *inode,
                else
                        goto found;
        }
-       set->timestamp = ktime_get_ns();
        rb_link_node(&set->rb_node, parent, p);
        rb_insert_color(&set->rb_node, root_node);
        list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
@@ -3114,6 +3113,7 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set,
        cache->fsgid = cred->fsgid;
        cache->group_info = get_group_info(cred->group_info);
        cache->mask = set->mask;
+       cache->timestamp = ktime_get_ns();
 
        /* The above field assignments must be visible
         * before this item appears on the lru.  We cannot easily