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 uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,
  16                                        void *buffer, uint16_t buflen);
  17 static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,
  18                                          void *buffer, uint16_t buflen);
  19
  20 static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,
  21                                         void *buffer, uint16_t buflen);
  22 static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,
  23                                      uint64_t *size);
  24 static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,
  25                                         void *buffer, uint16_t buflen);
  26 static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
  27                                                        const void *buffer,
  28                                                        uint16_t buflen);
  29
  30 struct fscache_netfs afs_cache_netfs = {
  31         .name                   = "afs",
  32         .version                = 1,
  33 };
  34
  35 struct fscache_cookie_def afs_cell_cache_index_def = {
  36         .name           = "AFS.cell",
  37         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  38         .get_key        = afs_cell_cache_get_key,
  39 };
  40
  41 struct fscache_cookie_def afs_volume_cache_index_def = {
  42         .name           = "AFS.volume",
  43         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  44         .get_key        = afs_volume_cache_get_key,
  45 };
  46
  47 struct fscache_cookie_def afs_vnode_cache_index_def = {
  48         .name                   = "AFS.vnode",
  49         .type                   = FSCACHE_COOKIE_TYPE_DATAFILE,
  50         .get_key                = afs_vnode_cache_get_key,
  51         .get_attr               = afs_vnode_cache_get_attr,
  52         .get_aux                = afs_vnode_cache_get_aux,
  53         .check_aux              = afs_vnode_cache_check_aux,
  54 };
  55
  56 /*
  57  * set the key for the index entry
  58  */
  59 static uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,
  60                                        void *buffer, uint16_t bufmax)
  61 {
  62         const struct afs_cell *cell = cookie_netfs_data;
  63         uint16_t klen;
  64
  65         _enter("%p,%p,%u", cell, buffer, bufmax);
  66
  67         klen = strlen(cell->name);
  68         if (klen > bufmax)
  69                 return 0;
  70
  71         memcpy(buffer, cell->name, klen);
  72         return klen;
  73 }
  74
  75 /*****************************************************************************/
  76 /*
  77  * set the key for the volume index entry
  78  */
  79 static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,
  80                                          void *buffer, uint16_t bufmax)
  81 {
  82         const struct afs_volume *volume = cookie_netfs_data;
  83         struct {
  84                 u64 volid;
  85         } __packed key;
  86
  87         _enter("{%u},%p,%u", volume->type, buffer, bufmax);
  88
  89         if (bufmax < sizeof(key))
  90                 return 0;
  91
  92         key.volid = volume->vid;
  93         memcpy(buffer, &key, sizeof(key));
  94         return sizeof(key);
  95 }
  96
  97 /*****************************************************************************/
  98 /*
  99  * set the key for the index entry
 100  */
 101 static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,
 102                                         void *buffer, uint16_t bufmax)
 103 {
 104         const struct afs_vnode *vnode = cookie_netfs_data;
 105         struct {
 106                 u32 vnode_id[3];
 107         } __packed key;
 108
 109         _enter("{%x,%x,%llx},%p,%u",
 110                vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
 111                buffer, bufmax);
 112
 113         /* Allow for a 96-bit key */
 114         memset(&key, 0, sizeof(key));
 115         key.vnode_id[0] = vnode->fid.vnode;
 116         key.vnode_id[1] = 0;
 117         key.vnode_id[2] = 0;
 118
 119         if (sizeof(key) > bufmax)
 120                 return 0;
 121
 122         memcpy(buffer, &key, sizeof(key));
 123         return sizeof(key);
 124 }
 125
 126 /*
 127  * provide updated file attributes
 128  */
 129 static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,
 130                                      uint64_t *size)
 131 {
 132         const struct afs_vnode *vnode = cookie_netfs_data;
 133
 134         _enter("{%x,%x,%llx},",
 135                vnode->fid.vnode, vnode->fid.unique,
 136                vnode->status.data_version);
 137
 138         *size = vnode->status.size;
 139 }
 140
 141 struct afs_vnode_cache_aux {
 142         u64 data_version;
 143         u32 fid_unique;
 144 } __packed;
 145
 146 /*
 147  * provide new auxiliary cache data
 148  */
 149 static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,
 150                                         void *buffer, uint16_t bufmax)
 151 {
 152         const struct afs_vnode *vnode = cookie_netfs_data;
 153         struct afs_vnode_cache_aux aux;
 154
 155         _enter("{%x,%x,%Lx},%p,%u",
 156                vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
 157                buffer, bufmax);
 158
 159         memset(&aux, 0, sizeof(aux));
 160         aux.data_version = vnode->status.data_version;
 161         aux.fid_unique = vnode->fid.unique;
 162
 163         if (bufmax < sizeof(aux))
 164                 return 0;
 165
 166         memcpy(buffer, &aux, sizeof(aux));
 167         return sizeof(aux);
 168 }
 169
 170 /*
 171  * check that the auxiliary data indicates that the entry is still valid
 172  */
 173 static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
 174                                                        const void *buffer,
 175                                                        uint16_t buflen)
 176 {
 177         struct afs_vnode *vnode = cookie_netfs_data;
 178         struct afs_vnode_cache_aux aux;
 179
 180         _enter("{%x,%x,%llx},%p,%u",
 181                vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
 182                buffer, buflen);
 183
 184         memcpy(&aux, buffer, sizeof(aux));
 185
 186         /* check the size of the data is what we're expecting */
 187         if (buflen != sizeof(aux)) {
 188                 _leave(" = OBSOLETE [len %hx != %zx]", buflen, sizeof(aux));
 189                 return FSCACHE_CHECKAUX_OBSOLETE;
 190         }
 191
 192         if (vnode->fid.unique != aux.fid_unique) {
 193                 _leave(" = OBSOLETE [uniq %x != %x]",
 194                        aux.fid_unique, vnode->fid.unique);
 195                 return FSCACHE_CHECKAUX_OBSOLETE;
 196         }
 197
 198         if (vnode->status.data_version != aux.data_version) {
 199                 _leave(" = OBSOLETE [vers %llx != %llx]",
 200                        aux.data_version, vnode->status.data_version);
 201                 return FSCACHE_CHECKAUX_OBSOLETE;
 202         }
 203
 204         _leave(" = SUCCESS");
 205         return FSCACHE_CHECKAUX_OKAY;
 206 }