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/* NFS FS-Cache index structure definition
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>

#include "internal.h"
#include "fscache.h"

#define NFSDBG_FACILITY NFSDBG_FSCACHE

/*
* Define the NFS filesystem for FS-Cache. Upon registration FS-Cache sticks
* the cookie for the top-level index object for NFS into here. The top-level
* index can than have other cache objects inserted into it.
*/
struct fscache_netfs nfs_fscache_netfs = {
.name = "nfs",
.version = 0,
};

/*
* Register NFS for caching
*/
int nfs_fscache_register(void)
{
return fscache_register_netfs(&nfs_fscache_netfs);
}

/*
* Unregister NFS for caching
*/
void nfs_fscache_unregister(void)
{
fscache_unregister_netfs(&nfs_fscache_netfs);
}

/*
* Layout of the key for an NFS server cache object.
*/
struct nfs_server_key {
uint16_t nfsversion; /* NFS protocol version */
uint16_t family; /* address family */
uint16_t port; /* IP port */
union {
struct in_addr ipv4_addr; /* IPv4 address */
struct in6_addr ipv6_addr; /* IPv6 address */
} addr[0];
};

/*
* Generate a key to describe a server in the main NFS index
* - We return the length of the key, or 0 if we can't generate one
*/
static uint16_t nfs_server_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct nfs_client *clp = cookie_netfs_data;
const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
struct nfs_server_key *key = buffer;
uint16_t len = sizeof(struct nfs_server_key);

key->nfsversion = clp->rpc_ops->version;
key->family = clp->cl_addr.ss_family;

memset(key, 0, len);

switch (clp->cl_addr.ss_family) {
case AF_INET:
key->port = sin->sin_port;
key->addr[0].ipv4_addr = sin->sin_addr;
len += sizeof(key->addr[0].ipv4_addr);
break;

case AF_INET6:
key->port = sin6->sin6_port;
key->addr[0].ipv6_addr = sin6->sin6_addr;
len += sizeof(key->addr[0].ipv6_addr);
break;

default:
printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
clp->cl_addr.ss_family);
len = 0;
break;
}

return len;
}

/*
* Define the server object for FS-Cache. This is used to describe a server
* object to fscache_acquire_cookie(). It is keyed by the NFS protocol and
* server address parameters.
*/
const struct fscache_cookie_def nfs_fscache_server_index_def = {
.name = "NFS.server",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = nfs_server_get_key,
};

/*
* Generate a key to describe a superblock key in the main NFS index
*/
static uint16_t nfs_super_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct nfs_fscache_key *key;
const struct nfs_server *nfss = cookie_netfs_data;
uint16_t len;

key = nfss->fscache_key;
len = sizeof(key->key) + key->key.uniq_len;
if (len > bufmax) {
len = 0;
} else {
memcpy(buffer, &key->key, sizeof(key->key));
memcpy(buffer + sizeof(key->key),
key->key.uniquifier, key->key.uniq_len);
}

return len;
}

/*
* Define the superblock object for FS-Cache. This is used to describe a
* superblock object to fscache_acquire_cookie(). It is keyed by all the NFS
* parameters that might cause a separate superblock.
*/
const struct fscache_cookie_def nfs_fscache_super_index_def = {
.name = "NFS.super",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = nfs_super_get_key,
};

/*
* Definition of the auxiliary data attached to NFS inode storage objects
* within the cache.
*
* The contents of this struct are recorded in the on-disk local cache in the
* auxiliary data attached to the data storage object backing an inode. This
* permits coherency to be managed when a new inode binds to an already extant
* cache object.
*/
struct nfs_fscache_inode_auxdata {
struct timespec mtime;
struct timespec ctime;
loff_t size;
u64 change_attr;
};

/*
* Generate a key to describe an NFS inode in an NFS server's index
*/
static uint16_t nfs_fscache_inode_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct nfs_inode *nfsi = cookie_netfs_data;
uint16_t nsize;

/* use the inode's NFS filehandle as the key */
nsize = nfsi->fh.size;
memcpy(buffer, nfsi->fh.data, nsize);
return nsize;
}

/*
* Get certain file attributes from the netfs data
* - This function can be absent for an index
* - Not permitted to return an error
* - The netfs data from the cookie being used as the source is presented
*/
static void nfs_fscache_inode_get_attr(const void *cookie_netfs_data,
uint64_t *size)
{
const struct nfs_inode *nfsi = cookie_netfs_data;

*size = nfsi->vfs_inode.i_size;
}

/*
* Get the auxiliary data from netfs data
* - This function can be absent if the index carries no state data
* - Should store the auxiliary data in the buffer
* - Should return the amount of amount stored
* - Not permitted to return an error
* - The netfs data from the cookie being used as the source is presented
*/
static uint16_t nfs_fscache_inode_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
struct nfs_fscache_inode_auxdata auxdata;
const struct nfs_inode *nfsi = cookie_netfs_data;

memset(&auxdata, 0, sizeof(auxdata));
auxdata.size = nfsi->vfs_inode.i_size;
auxdata.mtime = nfsi->vfs_inode.i_mtime;
auxdata.ctime = nfsi->vfs_inode.i_ctime;

if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
auxdata.change_attr = nfsi->vfs_inode.i_version;

if (bufmax > sizeof(auxdata))
bufmax = sizeof(auxdata);

memcpy(buffer, &auxdata, bufmax);
return bufmax;
}

/*
* Consult the netfs about the state of an object
* - This function can be absent if the index carries no state data
* - The netfs data from the cookie being used as the target is
* presented, as is the auxiliary data
*/
static
enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
const void *data,
uint16_t datalen)
{
struct nfs_fscache_inode_auxdata auxdata;
struct nfs_inode *nfsi = cookie_netfs_data;

if (datalen != sizeof(auxdata))
return FSCACHE_CHECKAUX_OBSOLETE;

memset(&auxdata, 0, sizeof(auxdata));
auxdata.size = nfsi->vfs_inode.i_size;
auxdata.mtime = nfsi->vfs_inode.i_mtime;
auxdata.ctime = nfsi->vfs_inode.i_ctime;

if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
auxdata.change_attr = nfsi->vfs_inode.i_version;

if (memcmp(data, &auxdata, datalen) != 0)
return FSCACHE_CHECKAUX_OBSOLETE;

return FSCACHE_CHECKAUX_OKAY;
}

/*
* Indication from FS-Cache that the cookie is no longer cached
* - This function is called when the backing store currently caching a cookie
* is removed
* - The netfs should use this to clean up any markers indicating cached pages
* - This is mandatory for any object that may have data
*/
static void nfs_fscache_inode_now_uncached(void *cookie_netfs_data)
{
struct nfs_inode *nfsi = cookie_netfs_data;
struct pagevec pvec;
pgoff_t first;
int loop, nr_pages;

pagevec_init(&pvec, 0);
first = 0;

dprintk("NFS: nfs_inode_now_uncached: nfs_inode 0x%p\n", nfsi);

for (;;) {
/* grab a bunch of pages to unmark */
nr_pages = pagevec_lookup(&pvec,
nfsi->vfs_inode.i_mapping,
first,
PAGEVEC_SIZE - pagevec_count(&pvec));
if (!nr_pages)
break;

for (loop = 0; loop < nr_pages; loop++)
ClearPageFsCache(pvec.pages[loop]);

first = pvec.pages[nr_pages - 1]->index + 1;

pvec.nr = nr_pages;
pagevec_release(&pvec);
cond_resched();
}
}

/*
* Get an extra reference on a read context.
* - This function can be absent if the completion function doesn't require a
* context.
* - The read context is passed back to NFS in the event that a data read on the
* cache fails with EIO - in which case the server must be contacted to
* retrieve the data, which requires the read context for security.
*/
static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
{
get_nfs_open_context(context);
}

/*
* Release an extra reference on a read context.
* - This function can be absent if the completion function doesn't require a
* context.
*/
static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
{
if (context)
put_nfs_open_context(context);
}

/*
* Define the inode object for FS-Cache. This is used to describe an inode
* object to fscache_acquire_cookie(). It is keyed by the NFS file handle for
* an inode.
*
* Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
* held in the cache auxiliary data for the data storage object with those in
* the inode struct in memory.
*/
const struct fscache_cookie_def nfs_fscache_inode_object_def = {
.name = "NFS.fh",
.type = FSCACHE_COOKIE_TYPE_DATAFILE,
.get_key = nfs_fscache_inode_get_key,
.get_attr = nfs_fscache_inode_get_attr,
.get_aux = nfs_fscache_inode_get_aux,
.check_aux = nfs_fscache_inode_check_aux,
.now_uncached = nfs_fscache_inode_now_uncached,
.get_context = nfs_fh_get_context,
.put_context = nfs_fh_put_context,
};
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