FS-Cache: Add netfs registration
Add functions to register and unregister a network filesystem or other client
of the FS-Cache service. This allocates and releases the cookie representing
the top-level index for a netfs, and makes it available to the netfs.
If the FS-Cache facility is disabled, then the calls are optimised away at
compile time.
Note that whilst this patch may appear to work with FS-Cache enabled and a
netfs attempting to use it, it will leak the cookie it allocates for the netfs
as fscache_relinquish_cookie() is implemented in a later patch. This will
cause the slab code to emit a warning when the module is removed.
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>
diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
new file mode 100644
index 0000000..e028b8e
--- /dev/null
+++ b/fs/fscache/netfs.c
@@ -0,0 +1,103 @@
+/* FS-Cache netfs (client) registration
+ *
+ * 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.
+ */
+
+#define FSCACHE_DEBUG_LEVEL COOKIE
+#include <linux/module.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+static LIST_HEAD(fscache_netfs_list);
+
+/*
+ * register a network filesystem for caching
+ */
+int __fscache_register_netfs(struct fscache_netfs *netfs)
+{
+ struct fscache_netfs *ptr;
+ int ret;
+
+ _enter("{%s}", netfs->name);
+
+ INIT_LIST_HEAD(&netfs->link);
+
+ /* allocate a cookie for the primary index */
+ netfs->primary_index =
+ kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
+
+ if (!netfs->primary_index) {
+ _leave(" = -ENOMEM");
+ return -ENOMEM;
+ }
+
+ /* initialise the primary index cookie */
+ atomic_set(&netfs->primary_index->usage, 1);
+ atomic_set(&netfs->primary_index->n_children, 0);
+
+ netfs->primary_index->def = &fscache_fsdef_netfs_def;
+ netfs->primary_index->parent = &fscache_fsdef_index;
+ netfs->primary_index->netfs_data = netfs;
+
+ atomic_inc(&netfs->primary_index->parent->usage);
+ atomic_inc(&netfs->primary_index->parent->n_children);
+
+ spin_lock_init(&netfs->primary_index->lock);
+ INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
+
+ /* check the netfs type is not already present */
+ down_write(&fscache_addremove_sem);
+
+ ret = -EEXIST;
+ list_for_each_entry(ptr, &fscache_netfs_list, link) {
+ if (strcmp(ptr->name, netfs->name) == 0)
+ goto already_registered;
+ }
+
+ list_add(&netfs->link, &fscache_netfs_list);
+ ret = 0;
+
+ printk(KERN_NOTICE "FS-Cache: Netfs '%s' registered for caching\n",
+ netfs->name);
+
+already_registered:
+ up_write(&fscache_addremove_sem);
+
+ if (ret < 0) {
+ netfs->primary_index->parent = NULL;
+ __fscache_cookie_put(netfs->primary_index);
+ netfs->primary_index = NULL;
+ }
+
+ _leave(" = %d", ret);
+ return ret;
+}
+EXPORT_SYMBOL(__fscache_register_netfs);
+
+/*
+ * unregister a network filesystem from the cache
+ * - all cookies must have been released first
+ */
+void __fscache_unregister_netfs(struct fscache_netfs *netfs)
+{
+ _enter("{%s.%u}", netfs->name, netfs->version);
+
+ down_write(&fscache_addremove_sem);
+
+ list_del(&netfs->link);
+ fscache_relinquish_cookie(netfs->primary_index, 0);
+
+ up_write(&fscache_addremove_sem);
+
+ printk(KERN_NOTICE "FS-Cache: Netfs '%s' unregistered from caching\n",
+ netfs->name);
+
+ _leave("");
+}
+EXPORT_SYMBOL(__fscache_unregister_netfs);