fs/fscache/netfs.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* FS-Cache netfs (client) registration
   3  *
   4  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define FSCACHE_DEBUG_LEVEL COOKIE
   9 #include <linux/module.h>
  10 #include <linux/slab.h>
  11 #include "internal.h"
  12
  13 /*
  14  * register a network filesystem for caching
  15  */
  16 int __fscache_register_netfs(struct fscache_netfs *netfs)
  17 {
  18         struct fscache_cookie *candidate, *cookie;
  19
  20         _enter("{%s}", netfs->name);
  21
  22         /* allocate a cookie for the primary index */
  23         candidate = fscache_alloc_cookie(&fscache_fsdef_index,
  24                                          &fscache_fsdef_netfs_def,
  25                                          netfs->name, strlen(netfs->name),
  26                                          &netfs->version, sizeof(netfs->version),
  27                                          netfs, 0);
  28         if (!candidate) {
  29                 _leave(" = -ENOMEM");
  30                 return -ENOMEM;
  31         }
  32
  33         candidate->flags = 1 << FSCACHE_COOKIE_ENABLED;
  34
  35         /* check the netfs type is not already present */
  36         cookie = fscache_hash_cookie(candidate);
  37         if (!cookie)
  38                 goto already_registered;
  39         if (cookie != candidate) {
  40                 trace_fscache_cookie(candidate, fscache_cookie_discard, 1);
  41                 fscache_free_cookie(candidate);
  42         }
  43
  44         fscache_cookie_get(cookie->parent, fscache_cookie_get_register_netfs);
  45         atomic_inc(&cookie->parent->n_children);
  46
  47         netfs->primary_index = cookie;
  48
  49         pr_notice("Netfs '%s' registered for caching\n", netfs->name);
  50         trace_fscache_netfs(netfs);
  51         _leave(" = 0");
  52         return 0;
  53
  54 already_registered:
  55         fscache_cookie_put(candidate, fscache_cookie_put_dup_netfs);
  56         _leave(" = -EEXIST");
  57         return -EEXIST;
  58 }
  59 EXPORT_SYMBOL(__fscache_register_netfs);
  60
  61 /*
  62  * unregister a network filesystem from the cache
  63  * - all cookies must have been released first
  64  */
  65 void __fscache_unregister_netfs(struct fscache_netfs *netfs)
  66 {
  67         _enter("{%s.%u}", netfs->name, netfs->version);
  68
  69         fscache_relinquish_cookie(netfs->primary_index, NULL, false);
  70         pr_notice("Netfs '%s' unregistered from caching\n", netfs->name);
  71
  72         _leave("");
  73 }
  74 EXPORT_SYMBOL(__fscache_unregister_netfs);