NFS: Make nfs_readdir revalidate less often

Make nfs_readdir revalidate only when we're at the beginning of the directory or
if the cached attributes have expired.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index bd7e1cc53b90..e474ca2b2bfe 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -818,7 +818,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
         nfs_readdir_descriptor_t my_desc,
                         *desc = &my_desc;
         struct nfs_open_dir_context *dir_ctx = file->private_data;
-        int res;
+        int res = 0;
 
         dfprintk(FILE, "NFS: readdir(%s/%s) starting at cookie %llu\n",
                         dentry->d_parent->d_name.name, dentry->d_name.name,
@@ -840,7 +840,8 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
         desc->plus = nfs_use_readdirplus(inode, ctx) ? 1 : 0;
 
         nfs_block_sillyrename(dentry);
-        res = nfs_revalidate_mapping(inode, file->f_mapping);
+        if (ctx->pos == 0 || nfs_attribute_cache_expired(inode))
+                res = nfs_revalidate_mapping(inode, file->f_mapping);
         if (res < 0)
                 goto out;