linux/fs/nfs/fscache-index.c
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   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 */
  30struct fscache_netfs nfs_fscache_netfs = {
  31        .name           = "nfs",
  32        .version        = 0,
  33};
  34
  35/*
  36 * Register NFS for caching
  37 */
  38int nfs_fscache_register(void)
  39{
  40        return fscache_register_netfs(&nfs_fscache_netfs);
  41}
  42
  43/*
  44 * Unregister NFS for caching
  45 */
  46void 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 */
  54struct 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 */
  68static 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        key->nfsversion = clp->rpc_ops->version;
  78        key->family = clp->cl_addr.ss_family;
  79
  80        memset(key, 0, len);
  81
  82        switch (clp->cl_addr.ss_family) {
  83        case AF_INET:
  84                key->port = sin->sin_port;
  85                key->addr[0].ipv4_addr = sin->sin_addr;
  86                len += sizeof(key->addr[0].ipv4_addr);
  87                break;
  88
  89        case AF_INET6:
  90                key->port = sin6->sin6_port;
  91                key->addr[0].ipv6_addr = sin6->sin6_addr;
  92                len += sizeof(key->addr[0].ipv6_addr);
  93                break;
  94
  95        default:
  96                printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
  97                       clp->cl_addr.ss_family);
  98                len = 0;
  99                break;
 100        }
 101
 102        return len;
 103}
 104
 105/*
 106 * Define the server object for FS-Cache.  This is used to describe a server
 107 * object to fscache_acquire_cookie().  It is keyed by the NFS protocol and
 108 * server address parameters.
 109 */
 110const struct fscache_cookie_def nfs_fscache_server_index_def = {
 111        .name           = "NFS.server",
 112        .type           = FSCACHE_COOKIE_TYPE_INDEX,
 113        .get_key        = nfs_server_get_key,
 114};
 115
 116/*
 117 * Generate a key to describe a superblock key in the main NFS index
 118 */
 119static uint16_t nfs_super_get_key(const void *cookie_netfs_data,
 120                                  void *buffer, uint16_t bufmax)
 121{
 122        const struct nfs_fscache_key *key;
 123        const struct nfs_server *nfss = cookie_netfs_data;
 124        uint16_t len;
 125
 126        key = nfss->fscache_key;
 127        len = sizeof(key->key) + key->key.uniq_len;
 128        if (len > bufmax) {
 129                len = 0;
 130        } else {
 131                memcpy(buffer, &key->key, sizeof(key->key));
 132                memcpy(buffer + sizeof(key->key),
 133                       key->key.uniquifier, key->key.uniq_len);
 134        }
 135
 136        return len;
 137}
 138
 139/*
 140 * Define the superblock object for FS-Cache.  This is used to describe a
 141 * superblock object to fscache_acquire_cookie().  It is keyed by all the NFS
 142 * parameters that might cause a separate superblock.
 143 */
 144const struct fscache_cookie_def nfs_fscache_super_index_def = {
 145        .name           = "NFS.super",
 146        .type           = FSCACHE_COOKIE_TYPE_INDEX,
 147        .get_key        = nfs_super_get_key,
 148};
 149
 150/*
 151 * Definition of the auxiliary data attached to NFS inode storage objects
 152 * within the cache.
 153 *
 154 * The contents of this struct are recorded in the on-disk local cache in the
 155 * auxiliary data attached to the data storage object backing an inode.  This
 156 * permits coherency to be managed when a new inode binds to an already extant
 157 * cache object.
 158 */
 159struct nfs_fscache_inode_auxdata {
 160        struct timespec mtime;
 161        struct timespec ctime;
 162        loff_t          size;
 163        u64             change_attr;
 164};
 165
 166/*
 167 * Generate a key to describe an NFS inode in an NFS server's index
 168 */
 169static uint16_t nfs_fscache_inode_get_key(const void *cookie_netfs_data,
 170                                          void *buffer, uint16_t bufmax)
 171{
 172        const struct nfs_inode *nfsi = cookie_netfs_data;
 173        uint16_t nsize;
 174
 175        /* use the inode's NFS filehandle as the key */
 176        nsize = nfsi->fh.size;
 177        memcpy(buffer, nfsi->fh.data, nsize);
 178        return nsize;
 179}
 180
 181/*
 182 * Get certain file attributes from the netfs data
 183 * - This function can be absent for an index
 184 * - Not permitted to return an error
 185 * - The netfs data from the cookie being used as the source is presented
 186 */
 187static void nfs_fscache_inode_get_attr(const void *cookie_netfs_data,
 188                                       uint64_t *size)
 189{
 190        const struct nfs_inode *nfsi = cookie_netfs_data;
 191
 192        *size = nfsi->vfs_inode.i_size;
 193}
 194
 195/*
 196 * Get the auxiliary data from netfs data
 197 * - This function can be absent if the index carries no state data
 198 * - Should store the auxiliary data in the buffer
 199 * - Should return the amount of amount stored
 200 * - Not permitted to return an error
 201 * - The netfs data from the cookie being used as the source is presented
 202 */
 203static uint16_t nfs_fscache_inode_get_aux(const void *cookie_netfs_data,
 204                                          void *buffer, uint16_t bufmax)
 205{
 206        struct nfs_fscache_inode_auxdata auxdata;
 207        const struct nfs_inode *nfsi = cookie_netfs_data;
 208
 209        memset(&auxdata, 0, sizeof(auxdata));
 210        auxdata.size = nfsi->vfs_inode.i_size;
 211        auxdata.mtime = nfsi->vfs_inode.i_mtime;
 212        auxdata.ctime = nfsi->vfs_inode.i_ctime;
 213
 214        if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 215                auxdata.change_attr = nfsi->vfs_inode.i_version;
 216
 217        if (bufmax > sizeof(auxdata))
 218                bufmax = sizeof(auxdata);
 219
 220        memcpy(buffer, &auxdata, bufmax);
 221        return bufmax;
 222}
 223
 224/*
 225 * Consult the netfs about the state of an object
 226 * - This function can be absent if the index carries no state data
 227 * - The netfs data from the cookie being used as the target is
 228 *   presented, as is the auxiliary data
 229 */
 230static
 231enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
 232                                                  const void *data,
 233                                                  uint16_t datalen)
 234{
 235        struct nfs_fscache_inode_auxdata auxdata;
 236        struct nfs_inode *nfsi = cookie_netfs_data;
 237
 238        if (datalen != sizeof(auxdata))
 239                return FSCACHE_CHECKAUX_OBSOLETE;
 240
 241        memset(&auxdata, 0, sizeof(auxdata));
 242        auxdata.size = nfsi->vfs_inode.i_size;
 243        auxdata.mtime = nfsi->vfs_inode.i_mtime;
 244        auxdata.ctime = nfsi->vfs_inode.i_ctime;
 245
 246        if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 247                auxdata.change_attr = nfsi->vfs_inode.i_version;
 248
 249        if (memcmp(data, &auxdata, datalen) != 0)
 250                return FSCACHE_CHECKAUX_OBSOLETE;
 251
 252        return FSCACHE_CHECKAUX_OKAY;
 253}
 254
 255/*
 256 * Indication from FS-Cache that the cookie is no longer cached
 257 * - This function is called when the backing store currently caching a cookie
 258 *   is removed
 259 * - The netfs should use this to clean up any markers indicating cached pages
 260 * - This is mandatory for any object that may have data
 261 */
 262static void nfs_fscache_inode_now_uncached(void *cookie_netfs_data)
 263{
 264        struct nfs_inode *nfsi = cookie_netfs_data;
 265        struct pagevec pvec;
 266        pgoff_t first;
 267        int loop, nr_pages;
 268
 269        pagevec_init(&pvec, 0);
 270        first = 0;
 271
 272        dprintk("NFS: nfs_inode_now_uncached: nfs_inode 0x%p\n", nfsi);
 273
 274        for (;;) {
 275                /* grab a bunch of pages to unmark */
 276                nr_pages = pagevec_lookup(&pvec,
 277                                          nfsi->vfs_inode.i_mapping,
 278                                          first,
 279                                          PAGEVEC_SIZE - pagevec_count(&pvec));
 280                if (!nr_pages)
 281                        break;
 282
 283                for (loop = 0; loop < nr_pages; loop++)
 284                        ClearPageFsCache(pvec.pages[loop]);
 285
 286                first = pvec.pages[nr_pages - 1]->index + 1;
 287
 288                pvec.nr = nr_pages;
 289                pagevec_release(&pvec);
 290                cond_resched();
 291        }
 292}
 293
 294/*
 295 * Get an extra reference on a read context.
 296 * - This function can be absent if the completion function doesn't require a
 297 *   context.
 298 * - The read context is passed back to NFS in the event that a data read on the
 299 *   cache fails with EIO - in which case the server must be contacted to
 300 *   retrieve the data, which requires the read context for security.
 301 */
 302static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
 303{
 304        get_nfs_open_context(context);
 305}
 306
 307/*
 308 * Release an extra reference on a read context.
 309 * - This function can be absent if the completion function doesn't require a
 310 *   context.
 311 */
 312static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
 313{
 314        if (context)
 315                put_nfs_open_context(context);
 316}
 317
 318/*
 319 * Define the inode object for FS-Cache.  This is used to describe an inode
 320 * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
 321 * an inode.
 322 *
 323 * Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
 324 * held in the cache auxiliary data for the data storage object with those in
 325 * the inode struct in memory.
 326 */
 327const struct fscache_cookie_def nfs_fscache_inode_object_def = {
 328        .name           = "NFS.fh",
 329        .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 330        .get_key        = nfs_fscache_inode_get_key,
 331        .get_attr       = nfs_fscache_inode_get_attr,
 332        .get_aux        = nfs_fscache_inode_get_aux,
 333        .check_aux      = nfs_fscache_inode_check_aux,
 334        .now_uncached   = nfs_fscache_inode_now_uncached,
 335        .get_context    = nfs_fh_get_context,
 336        .put_context    = nfs_fh_put_context,
 337};
 338
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