fs/nfs/fscache-index.c

   1 /* NFS FS-Cache index structure definition
   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 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/nfs_fs.h>
  17 #include <linux/nfs_fs_sb.h>
  18 #include <linux/in6.h>
  19
  20 #include "internal.h"
  21 #include "fscache.h"
  22
  23 #define NFSDBG_FACILITY         NFSDBG_FSCACHE
  24
  25 /*
  26  * Define the NFS filesystem for FS-Cache.  Upon registration FS-Cache sticks
  27  * the cookie for the top-level index object for NFS into here.  The top-level
  28  * index can than have other cache objects inserted into it.
  29  */
  30 struct fscache_netfs nfs_fscache_netfs = {
  31         .name           = "nfs",
  32         .version        = 0,
  33 };
  34
  35 /*
  36  * Register NFS for caching
  37  */
  38 int nfs_fscache_register(void)
  39 {
  40         return fscache_register_netfs(&nfs_fscache_netfs);
  41 }
  42
  43 /*
  44  * Unregister NFS for caching
  45  */
  46 void nfs_fscache_unregister(void)
  47 {
  48         fscache_unregister_netfs(&nfs_fscache_netfs);
  49 }
  50
  51 /*
  52  * Layout of the key for an NFS server cache object.
  53  */
  54 struct nfs_server_key {
  55         uint16_t        nfsversion;             /* NFS protocol version */
  56         uint16_t        family;                 /* address family */
  57         uint16_t        port;                   /* IP port */
  58         union {
  59                 struct in_addr  ipv4_addr;      /* IPv4 address */
  60                 struct in6_addr ipv6_addr;      /* IPv6 address */
  61         } addr[0];
  62 };
  63
  64 /*
  65  * Generate a key to describe a server in the main NFS index
  66  * - We return the length of the key, or 0 if we can't generate one
  67  */
  68 static uint16_t nfs_server_get_key(const void *cookie_netfs_data,
  69                                    void *buffer, uint16_t bufmax)
  70 {
  71         const struct nfs_client *clp = cookie_netfs_data;
  72         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
  73         const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
  74         struct nfs_server_key *key = buffer;
  75         uint16_t len = sizeof(struct nfs_server_key);
  76
  77         memset(key, 0, len);
  78         key->nfsversion = clp->rpc_ops->version;
  79         key->family = clp->cl_addr.ss_family;
  80
  81         switch (clp->cl_addr.ss_family) {
  82         case AF_INET:
  83                 key->port = sin->sin_port;
  84                 key->addr[0].ipv4_addr = sin->sin_addr;
  85                 len += sizeof(key->addr[0].ipv4_addr);
  86                 break;
  87
  88         case AF_INET6:
  89                 key->port = sin6->sin6_port;
  90                 key->addr[0].ipv6_addr = sin6->sin6_addr;
  91                 len += sizeof(key->addr[0].ipv6_addr);
  92                 break;
  93
  94         default:
  95                 printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
  96                        clp->cl_addr.ss_family);
  97                 len = 0;
  98                 break;
  99         }
 100
 101         return len;
 102 }
 103
 104 /*
 105  * Define the server object for FS-Cache.  This is used to describe a server
 106  * object to fscache_acquire_cookie().  It is keyed by the NFS protocol and
 107  * server address parameters.
 108  */
 109 const struct fscache_cookie_def nfs_fscache_server_index_def = {
 110         .name           = "NFS.server",
 111         .type           = FSCACHE_COOKIE_TYPE_INDEX,
 112         .get_key        = nfs_server_get_key,
 113 };
 114
 115 /*
 116  * Generate a key to describe a superblock key in the main NFS index
 117  */
 118 static uint16_t nfs_super_get_key(const void *cookie_netfs_data,
 119                                   void *buffer, uint16_t bufmax)
 120 {
 121         const struct nfs_fscache_key *key;
 122         const struct nfs_server *nfss = cookie_netfs_data;
 123         uint16_t len;
 124
 125         key = nfss->fscache_key;
 126         len = sizeof(key->key) + key->key.uniq_len;
 127         if (len > bufmax) {
 128                 len = 0;
 129         } else {
 130                 memcpy(buffer, &key->key, sizeof(key->key));
 131                 memcpy(buffer + sizeof(key->key),
 132                        key->key.uniquifier, key->key.uniq_len);
 133         }
 134
 135         return len;
 136 }
 137
 138 /*
 139  * Define the superblock object for FS-Cache.  This is used to describe a
 140  * superblock object to fscache_acquire_cookie().  It is keyed by all the NFS
 141  * parameters that might cause a separate superblock.
 142  */
 143 const struct fscache_cookie_def nfs_fscache_super_index_def = {
 144         .name           = "NFS.super",
 145         .type           = FSCACHE_COOKIE_TYPE_INDEX,
 146         .get_key        = nfs_super_get_key,
 147 };
 148
 149 /*
 150  * Definition of the auxiliary data attached to NFS inode storage objects
 151  * within the cache.
 152  *
 153  * The contents of this struct are recorded in the on-disk local cache in the
 154  * auxiliary data attached to the data storage object backing an inode.  This
 155  * permits coherency to be managed when a new inode binds to an already extant
 156  * cache object.
 157  */
 158 struct nfs_fscache_inode_auxdata {
 159         struct timespec mtime;
 160         struct timespec ctime;
 161         loff_t          size;
 162         u64             change_attr;
 163 };
 164
 165 /*
 166  * Generate a key to describe an NFS inode in an NFS server's index
 167  */
 168 static uint16_t nfs_fscache_inode_get_key(const void *cookie_netfs_data,
 169                                           void *buffer, uint16_t bufmax)
 170 {
 171         const struct nfs_inode *nfsi = cookie_netfs_data;
 172         uint16_t nsize;
 173
 174         /* use the inode's NFS filehandle as the key */
 175         nsize = nfsi->fh.size;
 176         memcpy(buffer, nfsi->fh.data, nsize);
 177         return nsize;
 178 }
 179
 180 /*
 181  * Get certain file attributes from the netfs data
 182  * - This function can be absent for an index
 183  * - Not permitted to return an error
 184  * - The netfs data from the cookie being used as the source is presented
 185  */
 186 static void nfs_fscache_inode_get_attr(const void *cookie_netfs_data,
 187                                        uint64_t *size)
 188 {
 189         const struct nfs_inode *nfsi = cookie_netfs_data;
 190
 191         *size = nfsi->vfs_inode.i_size;
 192 }
 193
 194 /*
 195  * Get the auxiliary data from netfs data
 196  * - This function can be absent if the index carries no state data
 197  * - Should store the auxiliary data in the buffer
 198  * - Should return the amount of amount stored
 199  * - Not permitted to return an error
 200  * - The netfs data from the cookie being used as the source is presented
 201  */
 202 static uint16_t nfs_fscache_inode_get_aux(const void *cookie_netfs_data,
 203                                           void *buffer, uint16_t bufmax)
 204 {
 205         struct nfs_fscache_inode_auxdata auxdata;
 206         const struct nfs_inode *nfsi = cookie_netfs_data;
 207
 208         memset(&auxdata, 0, sizeof(auxdata));
 209         auxdata.size = nfsi->vfs_inode.i_size;
 210         auxdata.mtime = nfsi->vfs_inode.i_mtime;
 211         auxdata.ctime = nfsi->vfs_inode.i_ctime;
 212
 213         if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 214                 auxdata.change_attr = nfsi->vfs_inode.i_version;
 215
 216         if (bufmax > sizeof(auxdata))
 217                 bufmax = sizeof(auxdata);
 218
 219         memcpy(buffer, &auxdata, bufmax);
 220         return bufmax;
 221 }
 222
 223 /*
 224  * Consult the netfs about the state of an object
 225  * - This function can be absent if the index carries no state data
 226  * - The netfs data from the cookie being used as the target is
 227  *   presented, as is the auxiliary data
 228  */
 229 static
 230 enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
 231                                                   const void *data,
 232                                                   uint16_t datalen)
 233 {
 234         struct nfs_fscache_inode_auxdata auxdata;
 235         struct nfs_inode *nfsi = cookie_netfs_data;
 236
 237         if (datalen != sizeof(auxdata))
 238                 return FSCACHE_CHECKAUX_OBSOLETE;
 239
 240         memset(&auxdata, 0, sizeof(auxdata));
 241         auxdata.size = nfsi->vfs_inode.i_size;
 242         auxdata.mtime = nfsi->vfs_inode.i_mtime;
 243         auxdata.ctime = nfsi->vfs_inode.i_ctime;
 244
 245         if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 246                 auxdata.change_attr = nfsi->vfs_inode.i_version;
 247
 248         if (memcmp(data, &auxdata, datalen) != 0)
 249                 return FSCACHE_CHECKAUX_OBSOLETE;
 250
 251         return FSCACHE_CHECKAUX_OKAY;
 252 }
 253
 254 /*
 255  * Get an extra reference on a read context.
 256  * - This function can be absent if the completion function doesn't require a
 257  *   context.
 258  * - The read context is passed back to NFS in the event that a data read on the
 259  *   cache fails with EIO - in which case the server must be contacted to
 260  *   retrieve the data, which requires the read context for security.
 261  */
 262 static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
 263 {
 264         get_nfs_open_context(context);
 265 }
 266
 267 /*
 268  * Release an extra reference on a read context.
 269  * - This function can be absent if the completion function doesn't require a
 270  *   context.
 271  */
 272 static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
 273 {
 274         if (context)
 275                 put_nfs_open_context(context);
 276 }
 277
 278 /*
 279  * Define the inode object for FS-Cache.  This is used to describe an inode
 280  * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
 281  * an inode.
 282  *
 283  * Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
 284  * held in the cache auxiliary data for the data storage object with those in
 285  * the inode struct in memory.
 286  */
 287 const struct fscache_cookie_def nfs_fscache_inode_object_def = {
 288         .name           = "NFS.fh",
 289         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 290         .get_key        = nfs_fscache_inode_get_key,
 291         .get_attr       = nfs_fscache_inode_get_attr,
 292         .get_aux        = nfs_fscache_inode_get_aux,
 293         .check_aux      = nfs_fscache_inode_check_aux,
 294         .get_context    = nfs_fh_get_context,
 295         .put_context    = nfs_fh_put_context,
 296 };