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>

fs/nfs/Makefile

@@ -15,4 +15,4 @@ nfs-$(CONFIG_NFS_V4)	+= nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o \
 			   callback.o callback_xdr.o callback_proc.o \
 			   nfs4namespace.o
 nfs-$(CONFIG_SYSCTL) += sysctl.o
-nfs-$(CONFIG_NFS_FSCACHE) += fscache-index.o
+nfs-$(CONFIG_NFS_FSCACHE) += fscache.o fscache-index.o

fs/nfs/client.c

@@ -45,6 +45,7 @@
 #include "delegation.h"
 #include "iostat.h"
 #include "internal.h"
+#include "fscache.h"
 
 #define NFSDBG_FACILITY		NFSDBG_CLIENT
 
@@ -154,6 +155,8 @@ static struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_
 	if (!IS_ERR(cred))
 		clp->cl_machine_cred = cred;
 
+	nfs_fscache_get_client_cookie(clp);
+
 	return clp;
 
 error_3:
@@ -187,6 +190,8 @@ static void nfs_free_client(struct nfs_client *clp)
 
 	nfs4_shutdown_client(clp);
 
+	nfs_fscache_release_client_cookie(clp);
+
 	/* -EIO all pending I/O */
 	if (!IS_ERR(clp->cl_rpcclient))
 		rpc_shutdown_client(clp->cl_rpcclient);

fs/nfs/fscache-index.c

@@ -47,3 +47,68 @@ void nfs_fscache_unregister(void)
 {
 	fscache_unregister_netfs(&nfs_fscache_netfs);
 }
+
+/*
+ * Layout of the key for an NFS server cache object.
+ */
+struct nfs_server_key {
+	uint16_t	nfsversion;		/* NFS protocol version */
+	uint16_t	family;			/* address family */
+	uint16_t	port;			/* IP port */
+	union {
+		struct in_addr	ipv4_addr;	/* IPv4 address */
+		struct in6_addr ipv6_addr;	/* IPv6 address */
+	} addr[0];
+};
+
+/*
+ * Generate a key to describe a server in the main NFS index
+ * - We return the length of the key, or 0 if we can't generate one
+ */
+static uint16_t nfs_server_get_key(const void *cookie_netfs_data,
+				   void *buffer, uint16_t bufmax)
+{
+	const struct nfs_client *clp = cookie_netfs_data;
+	const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
+	const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
+	struct nfs_server_key *key = buffer;
+	uint16_t len = sizeof(struct nfs_server_key);
+
+	key->nfsversion = clp->rpc_ops->version;
+	key->family = clp->cl_addr.ss_family;
+
+	memset(key, 0, len);
+
+	switch (clp->cl_addr.ss_family) {
+	case AF_INET:
+		key->port = sin->sin_port;
+		key->addr[0].ipv4_addr = sin->sin_addr;
+		len += sizeof(key->addr[0].ipv4_addr);
+		break;
+
+	case AF_INET6:
+		key->port = sin6->sin6_port;
+		key->addr[0].ipv6_addr = sin6->sin6_addr;
+		len += sizeof(key->addr[0].ipv6_addr);
+		break;
+
+	default:
+		printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
+		       clp->cl_addr.ss_family);
+		len = 0;
+		break;
+	}
+
+	return len;
+}
+
+/*
+ * Define the server object for FS-Cache.  This is used to describe a server
+ * object to fscache_acquire_cookie().  It is keyed by the NFS protocol and
+ * server address parameters.
+ */
+const struct fscache_cookie_def nfs_fscache_server_index_def = {
+	.name		= "NFS.server",
+	.type 		= FSCACHE_COOKIE_TYPE_INDEX,
+	.get_key	= nfs_server_get_key,
+};

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;
+}

fs/nfs/fscache.h

@@ -23,13 +23,23 @@
  * fscache-index.c
  */
 extern struct fscache_netfs nfs_fscache_netfs;
+extern const struct fscache_cookie_def nfs_fscache_server_index_def;
 
 extern int nfs_fscache_register(void);
 extern void nfs_fscache_unregister(void);
 
+/*
+ * fscache.c
+ */
+extern void nfs_fscache_get_client_cookie(struct nfs_client *);
+extern void nfs_fscache_release_client_cookie(struct nfs_client *);
+
 #else /* CONFIG_NFS_FSCACHE */
 static inline int nfs_fscache_register(void) { return 0; }
 static inline void nfs_fscache_unregister(void) {}
 
+static inline void nfs_fscache_get_client_cookie(struct nfs_client *clp) {}
+static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
+
 #endif /* CONFIG_NFS_FSCACHE */
 #endif /* _NFS_FSCACHE_H */

include/linux/nfs_fs_sb.h

@@ -64,6 +64,10 @@ struct nfs_client {
 	char			cl_ipaddr[48];
 	unsigned char		cl_id_uniquifier;
 #endif
+
+#ifdef CONFIG_NFS_FSCACHE
+	struct fscache_cookie	*fscache;	/* client index cache cookie */
+#endif
 };
 
 /*