fs/fscache/fsdef.c

   1 /* fsdef.c: filesystem index definition
   2  *
   3  * Copyright (C) 2004 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/module.h>
  13 #include "fscache-int.h"
  14
  15 static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
  16                                             void *buffer, uint16_t bufmax);
  17
  18 static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
  19                                             void *buffer, uint16_t bufmax);
  20
  21 static fscache_checkaux_t fscache_fsdef_netfs_check_aux(void *cookie_netfs_data,
  22                                                         const void *data,
  23                                                         uint16_t datalen);
  24
  25 struct fscache_cookie_def fscache_fsdef_netfs_def = {
  26         .name           = "FSDEF.netfs",
  27         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  28         .get_key        = fscache_fsdef_netfs_get_key,
  29         .get_aux        = fscache_fsdef_netfs_get_aux,
  30         .check_aux      = fscache_fsdef_netfs_check_aux,
  31 };
  32
  33 struct fscache_cookie fscache_fsdef_index = {
  34         .usage          = ATOMIC_INIT(1),
  35         .def            = NULL,
  36         .sem            = __RWSEM_INITIALIZER(fscache_fsdef_index.sem),
  37         .backing_objects = HLIST_HEAD_INIT,
  38 };
  39
  40 EXPORT_SYMBOL(fscache_fsdef_index);
  41
  42 /*****************************************************************************/
  43 /*
  44  * get the key data for an FSDEF index record
  45  */
  46 static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
  47                                             void *buffer, uint16_t bufmax)
  48 {
  49         const struct fscache_netfs *netfs = cookie_netfs_data;
  50         unsigned klen;
  51
  52         _enter("{%s.%u},", netfs->name, netfs->version);
  53
  54         klen = strlen(netfs->name);
  55         if (klen > bufmax)
  56                 return 0;
  57
  58         memcpy(buffer, netfs->name, klen);
  59         return klen;
  60 }
  61
  62 /*****************************************************************************/
  63 /*
  64  * get the auxilliary data for an FSDEF index record
  65  */
  66 static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
  67                                             void *buffer, uint16_t bufmax)
  68 {
  69         const struct fscache_netfs *netfs = cookie_netfs_data;
  70         unsigned dlen;
  71
  72         _enter("{%s.%u},", netfs->name, netfs->version);
  73
  74         dlen = sizeof(uint32_t);
  75         if (dlen > bufmax)
  76                 return 0;
  77
  78         memcpy(buffer, &netfs->version, dlen);
  79         return dlen;
  80 }
  81
  82 /*****************************************************************************/
  83 /*
  84  * check that the version stored in the auxilliary data is correct
  85  */
  86 static fscache_checkaux_t fscache_fsdef_netfs_check_aux(void *cookie_netfs_data,
  87                                                         const void *data,
  88                                                         uint16_t datalen)
  89 {
  90         struct fscache_netfs *netfs = cookie_netfs_data;
  91         uint32_t version;
  92
  93         _enter("{%s},,%hu", netfs->name, datalen);
  94
  95         if (datalen != sizeof(version)) {
  96                 _leave(" = OBSOLETE [dl=%d v=%d]",
  97                        datalen, sizeof(version));
  98                 return FSCACHE_CHECKAUX_OBSOLETE;
  99         }
 100
 101         memcpy(&version, data, sizeof(version));
 102         if (version != netfs->version) {
 103                 _leave(" = OBSOLETE [ver=%x net=%x]",
 104                        version, netfs->version);
 105                 return FSCACHE_CHECKAUX_OBSOLETE;
 106         }
 107
 108         _leave(" = OKAY");
 109         return FSCACHE_CHECKAUX_OKAY;
 110 }