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  */
  20 int __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
  58 already_registered:
  59         fscache_cookie_put(candidate, fscache_cookie_put_dup_netfs);
  60         _leave(" = -EEXIST");
  61         return -EEXIST;
  62 }
  63 EXPORT_SYMBOL(__fscache_register_netfs);
  64
  65 /*
  66  * unregister a network filesystem from the cache
  67  * - all cookies must have been released first
  68  */
  69 void __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 }
  78 EXPORT_SYMBOL(__fscache_unregister_netfs);