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  */
  31 struct fscache_netfs nfs_fscache_netfs = {
  32         .name           = "nfs",
  33         .version        = 0,
  34 };
  35
  36 /*
  37  * Register NFS for caching
  38  */
  39 int nfs_fscache_register(void)
  40 {
  41         return fscache_register_netfs(&nfs_fscache_netfs);
  42 }
  43
  44 /*
  45  * Unregister NFS for caching
  46  */
  47 void 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  */
  57 const 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  */
  67 const 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  */
  78 static
  79 enum 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  */
 113 static 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  */
 123 static 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  */
 138 const 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 };