LXR linux/fs/fscache/netfs.c

   1/* FS-Cache netfs (client) registration
   2 *
   3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11
  12#define FSCACHE_DEBUG_LEVEL COOKIE
  13#include <linux/module.h>
  14#include <linux/slab.h>
  15#include "internal.h"
  16
  17/*
  18 * register a network filesystem for caching
  19 */
  20int __fscache_register_netfs(struct fscache_netfs *netfs)
  21{
  22        struct fscache_cookie *candidate, *cookie;
  23
  24        _enter("{%s}", netfs->name);
  25
  26        /* allocate a cookie for the primary index */
  27        candidate = fscache_alloc_cookie(&fscache_fsdef_index,
  28                                         &fscache_fsdef_netfs_def,
  29                                         netfs->name, strlen(netfs->name),
  30                                         &netfs->version, sizeof(netfs->version),
  31                                         netfs, 0);
  32        if (!candidate) {
  33                _leave(" = -ENOMEM");
  34                return -ENOMEM;
  35        }
  36
  37        candidate->flags = 1 << FSCACHE_COOKIE_ENABLED;
  38
  39        /* check the netfs type is not already present */
  40        cookie = fscache_hash_cookie(candidate);
  41        if (!cookie)
  42                goto already_registered;
  43        if (cookie != candidate) {
  44                trace_fscache_cookie(candidate, fscache_cookie_discard, 1);
  45                fscache_free_cookie(candidate);
  46        }
  47
  48        fscache_cookie_get(cookie->parent, fscache_cookie_get_register_netfs);
  49        atomic_inc(&cookie->parent->n_children);
  50
  51        netfs->primary_index = cookie;
  52
  53        pr_notice("Netfs '%s' registered for caching\n", netfs->name);
  54        trace_fscache_netfs(netfs);
  55        _leave(" = 0");
  56        return 0;
  57
  58already_registered:
  59        fscache_cookie_put(candidate, fscache_cookie_put_dup_netfs);
  60        _leave(" = -EEXIST");
  61        return -EEXIST;
  62}
  63EXPORT_SYMBOL(__fscache_register_netfs);
  64
  65/*
  66 * unregister a network filesystem from the cache
  67 * - all cookies must have been released first
  68 */
  69void __fscache_unregister_netfs(struct fscache_netfs *netfs)
  70{
  71        _enter("{%s.%u}", netfs->name, netfs->version);
  72
  73        fscache_relinquish_cookie(netfs->primary_index, NULL, false);
  74        pr_notice("Netfs '%s' unregistered from caching\n", netfs->name);
  75
  76        _leave("");
  77}
  78EXPORT_SYMBOL(__fscache_unregister_netfs);
  79