LXR linux/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#include <linux/iversion.h>
  20
  21#include "internal.h"
  22#include "fscache.h"
  23
  24#define NFSDBG_FACILITY         NFSDBG_FSCACHE
  25
  26/*
  27 * Define the NFS filesystem for FS-Cache.  Upon registration FS-Cache sticks
  28 * the cookie for the top-level index object for NFS into here.  The top-level
  29 * index can than have other cache objects inserted into it.
  30 */
  31struct fscache_netfs nfs_fscache_netfs = {
  32        .name           = "nfs",
  33        .version        = 0,
  34};
  35
  36/*
  37 * Register NFS for caching
  38 */
  39int nfs_fscache_register(void)
  40{
  41        return fscache_register_netfs(&nfs_fscache_netfs);
  42}
  43
  44/*
  45 * Unregister NFS for caching
  46 */
  47void nfs_fscache_unregister(void)
  48{
  49        fscache_unregister_netfs(&nfs_fscache_netfs);
  50}
  51
  52/*
  53 * Define the server object for FS-Cache.  This is used to describe a server
  54 * object to fscache_acquire_cookie().  It is keyed by the NFS protocol and
  55 * server address parameters.
  56 */
  57const struct fscache_cookie_def nfs_fscache_server_index_def = {
  58        .name           = "NFS.server",
  59        .type           = FSCACHE_COOKIE_TYPE_INDEX,
  60};
  61
  62/*
  63 * Define the superblock object for FS-Cache.  This is used to describe a
  64 * superblock object to fscache_acquire_cookie().  It is keyed by all the NFS
  65 * parameters that might cause a separate superblock.
  66 */
  67const struct fscache_cookie_def nfs_fscache_super_index_def = {
  68        .name           = "NFS.super",
  69        .type           = FSCACHE_COOKIE_TYPE_INDEX,
  70};
  71
  72/*
  73 * Consult the netfs about the state of an object
  74 * - This function can be absent if the index carries no state data
  75 * - The netfs data from the cookie being used as the target is
  76 *   presented, as is the auxiliary data
  77 */
  78static
  79enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
  80                                                  const void *data,
  81                                                  uint16_t datalen,
  82                                                  loff_t object_size)
  83{
  84        struct nfs_fscache_inode_auxdata auxdata;
  85        struct nfs_inode *nfsi = cookie_netfs_data;
  86
  87        if (datalen != sizeof(auxdata))
  88                return FSCACHE_CHECKAUX_OBSOLETE;
  89
  90        memset(&auxdata, 0, sizeof(auxdata));
  91        auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
  92        auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
  93        auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
  94        auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
  95
  96        if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
  97                auxdata.change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
  98
  99        if (memcmp(data, &auxdata, datalen) != 0)
 100                return FSCACHE_CHECKAUX_OBSOLETE;
 101
 102        return FSCACHE_CHECKAUX_OKAY;
 103}
 104
 105/*
 106 * Get an extra reference on a read context.
 107 * - This function can be absent if the completion function doesn't require a
 108 *   context.
 109 * - The read context is passed back to NFS in the event that a data read on the
 110 *   cache fails with EIO - in which case the server must be contacted to
 111 *   retrieve the data, which requires the read context for security.
 112 */
 113static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
 114{
 115        get_nfs_open_context(context);
 116}
 117
 118/*
 119 * Release an extra reference on a read context.
 120 * - This function can be absent if the completion function doesn't require a
 121 *   context.
 122 */
 123static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
 124{
 125        if (context)
 126                put_nfs_open_context(context);
 127}
 128
 129/*
 130 * Define the inode object for FS-Cache.  This is used to describe an inode
 131 * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
 132 * an inode.
 133 *
 134 * Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
 135 * held in the cache auxiliary data for the data storage object with those in
 136 * the inode struct in memory.
 137 */
 138const struct fscache_cookie_def nfs_fscache_inode_object_def = {
 139        .name           = "NFS.fh",
 140        .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 141        .check_aux      = nfs_fscache_inode_check_aux,
 142        .get_context    = nfs_fh_get_context,
 143        .put_context    = nfs_fh_put_context,
 144};
 145