fs/afs/cache.c

   1 /* AFS caching stuff
   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 License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/sched.h>
  13 #include "internal.h"
  14
  15 static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
  16                                                        const void *buffer,
  17                                                        uint16_t buflen,
  18                                                        loff_t object_size);
  19
  20 struct fscache_netfs afs_cache_netfs = {
  21         .name                   = "afs",
  22         .version                = 2,
  23 };
  24
  25 struct fscache_cookie_def afs_cell_cache_index_def = {
  26         .name           = "AFS.cell",
  27         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  28 };
  29
  30 struct fscache_cookie_def afs_volume_cache_index_def = {
  31         .name           = "AFS.volume",
  32         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  33 };
  34
  35 struct fscache_cookie_def afs_vnode_cache_index_def = {
  36         .name           = "AFS.vnode",
  37         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
  38         .check_aux      = afs_vnode_cache_check_aux,
  39 };
  40
  41 /*
  42  * check that the auxiliary data indicates that the entry is still valid
  43  */
  44 static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
  45                                                        const void *buffer,
  46                                                        uint16_t buflen,
  47                                                        loff_t object_size)
  48 {
  49         struct afs_vnode *vnode = cookie_netfs_data;
  50         struct afs_vnode_cache_aux aux;
  51
  52         _enter("{%x,%x,%llx},%p,%u",
  53                vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
  54                buffer, buflen);
  55
  56         memcpy(&aux, buffer, sizeof(aux));
  57
  58         /* check the size of the data is what we're expecting */
  59         if (buflen != sizeof(aux)) {
  60                 _leave(" = OBSOLETE [len %hx != %zx]", buflen, sizeof(aux));
  61                 return FSCACHE_CHECKAUX_OBSOLETE;
  62         }
  63
  64         if (vnode->status.data_version != aux.data_version) {
  65                 _leave(" = OBSOLETE [vers %llx != %llx]",
  66                        aux.data_version, vnode->status.data_version);
  67                 return FSCACHE_CHECKAUX_OBSOLETE;
  68         }
  69
  70         _leave(" = SUCCESS");
  71         return FSCACHE_CHECKAUX_OKAY;
  72 }