NFS: Define and create server-level objects

Define and create server-level cache index objects (as managed by nfs_client
structs).

Each server object is created in the NFS top-level index object and is itself
an index into which superblock-level objects are inserted.

Ideally there would be one superblock-level object per server, and the former
would be folded into the latter; however, since the "nosharecache" option
exists this isn't possible.

The server object key is a sequence consisting of:

 (1) NFS version

 (2) Server address family (eg: AF_INET or AF_INET6)

 (3) Server port.

 (4) Server IP address.

The key blob is of variable length, depending on the length of (4).

The server object is given no coherency data to carry in the auxiliary data
permitted by the cache.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
new file mode 100644
index 000000000000..c3f056f89477
--- /dev/null
+++ b/fs/nfs/fscache.c
@@ -0,0 +1,52 @@
+/* NFS filesystem cache interface
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_fs_sb.h>
+#include <linux/in6.h>
+#include <linux/seq_file.h>
+
+#include "internal.h"
+#include "fscache.h"
+
+#define NFSDBG_FACILITY         NFSDBG_FSCACHE
+
+/*
+ * Get the per-client index cookie for an NFS client if the appropriate mount
+ * flag was set
+ * - We always try and get an index cookie for the client, but get filehandle
+ *   cookies on a per-superblock basis, depending on the mount flags
+ */
+void nfs_fscache_get_client_cookie(struct nfs_client *clp)
+{
+        /* create a cache index for looking up filehandles */
+        clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
+                                              &nfs_fscache_server_index_def,
+                                              clp);
+        dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
+                 clp, clp->fscache);
+}
+
+/*
+ * Dispose of a per-client cookie
+ */
+void nfs_fscache_release_client_cookie(struct nfs_client *clp)
+{
+        dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
+                 clp, clp->fscache);
+
+        fscache_relinquish_cookie(clp->fscache, 0);
+        clp->fscache = NULL;
+}