/* 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'
  ",
  		       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
  ", 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,
  };