/*
   *   fs/cifs/cache.c - CIFS filesystem cache index structure definitions
   *
   *   Copyright (c) 2010 Novell, Inc.
   *   Authors(s): Suresh Jayaraman (sjayaraman@suse.de>
   *
   *   This library is free software; you can redistribute it and/or modify
   *   it under the terms of the GNU Lesser General Public License as published
   *   by the Free Software Foundation; either version 2.1 of the License, or
   *   (at your option) any later version.
   *
   *   This library is distributed in the hope that it will be useful,
   *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
   *   the GNU Lesser General Public License for more details.
   *
   *   You should have received a copy of the GNU Lesser General Public License
   *   along with this library; if not, write to the Free Software
   *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   */
  #include "fscache.h"
  #include "cifs_debug.h"
  
  /*
   * CIFS filesystem definition for FS-Cache
   */
  struct fscache_netfs cifs_fscache_netfs = {
  	.name = "cifs",
  	.version = 0,
  };
  
  /*
   * Register CIFS for caching with FS-Cache
   */
  int cifs_fscache_register(void)
  {
  	return fscache_register_netfs(&cifs_fscache_netfs);
  }
  
  /*
   * Unregister CIFS for caching
   */
  void cifs_fscache_unregister(void)
  {
  	fscache_unregister_netfs(&cifs_fscache_netfs);
  }
  
  /*
   * Key layout of CIFS server cache index object
   */
  struct cifs_server_key {
  	uint16_t	family;		/* address family */
  	__be16		port;		/* IP port */
  	union {
  		struct in_addr	ipv4_addr;
  		struct in6_addr	ipv6_addr;
  	} addr[0];
  };
  
  /*
   * Server object keyed by {IPaddress,port,family} tuple
   */
  static uint16_t cifs_server_get_key(const void *cookie_netfs_data,
  				   void *buffer, uint16_t maxbuf)
  {
  	const struct TCP_Server_Info *server = cookie_netfs_data;
  	const struct sockaddr *sa = (struct sockaddr *) &server->dstaddr;
  	const struct sockaddr_in *addr = (struct sockaddr_in *) sa;
  	const struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *) sa;
  	struct cifs_server_key *key = buffer;
  	uint16_t key_len = sizeof(struct cifs_server_key);
  
  	memset(key, 0, key_len);
  
  	/*
  	 * Should not be a problem as sin_family/sin6_family overlays
  	 * sa_family field
  	 */
  	switch (sa->sa_family) {
  	case AF_INET:
  		key->family = sa->sa_family;
  		key->port = addr->sin_port;
  		key->addr[0].ipv4_addr = addr->sin_addr;
  		key_len += sizeof(key->addr[0].ipv4_addr);
  		break;
  
  	case AF_INET6:
  		key->family = sa->sa_family;
  		key->port = addr6->sin6_port;
  		key->addr[0].ipv6_addr = addr6->sin6_addr;
  		key_len += sizeof(key->addr[0].ipv6_addr);
  		break;
  
  	default:
  		cifs_dbg(VFS, "Unknown network family '%d'
  ", sa->sa_family);
  		key_len = 0;
  		break;
  	}
  
  	return key_len;
  }
  
  /*
   * Server object for FS-Cache
   */
  const struct fscache_cookie_def cifs_fscache_server_index_def = {
  	.name = "CIFS.server",
  	.type = FSCACHE_COOKIE_TYPE_INDEX,
  	.get_key = cifs_server_get_key,
  };
  
  /*
   * Auxiliary data attached to CIFS superblock within the cache
   */
  struct cifs_fscache_super_auxdata {
  	u64	resource_id;		/* unique server resource id */
  };
  
  static char *extract_sharename(const char *treename)
  {
  	const char *src;
  	char *delim, *dst;
  	int len;
  
  	/* skip double chars at the beginning */
  	src = treename + 2;
  
  	/* share name is always preceded by '\\' now */
  	delim = strchr(src, '\\');
  	if (!delim)
  		return ERR_PTR(-EINVAL);
  	delim++;
  	len = strlen(delim);
  
  	/* caller has to free the memory */
  	dst = kstrndup(delim, len, GFP_KERNEL);
  	if (!dst)
  		return ERR_PTR(-ENOMEM);
  
  	return dst;
  }
  
  /*
   * Superblock object currently keyed by share name
   */
  static uint16_t cifs_super_get_key(const void *cookie_netfs_data, void *buffer,
  				   uint16_t maxbuf)
  {
  	const struct cifs_tcon *tcon = cookie_netfs_data;
  	char *sharename;
  	uint16_t len;
  
  	sharename = extract_sharename(tcon->treeName);
  	if (IS_ERR(sharename)) {
  		cifs_dbg(FYI, "%s: couldn't extract sharename
  ", __func__);
  		sharename = NULL;
  		return 0;
  	}
  
  	len = strlen(sharename);
  	if (len > maxbuf)
  		return 0;
  
  	memcpy(buffer, sharename, len);
  
  	kfree(sharename);
  
  	return len;
  }
  
  static uint16_t
  cifs_fscache_super_get_aux(const void *cookie_netfs_data, void *buffer,
  			   uint16_t maxbuf)
  {
  	struct cifs_fscache_super_auxdata auxdata;
  	const struct cifs_tcon *tcon = cookie_netfs_data;
  
  	memset(&auxdata, 0, sizeof(auxdata));
  	auxdata.resource_id = tcon->resource_id;
  
  	if (maxbuf > sizeof(auxdata))
  		maxbuf = sizeof(auxdata);
  
  	memcpy(buffer, &auxdata, maxbuf);
  
  	return maxbuf;
  }
  
  static enum
  fscache_checkaux cifs_fscache_super_check_aux(void *cookie_netfs_data,
  					      const void *data,
  					      uint16_t datalen)
  {
  	struct cifs_fscache_super_auxdata auxdata;
  	const struct cifs_tcon *tcon = cookie_netfs_data;
  
  	if (datalen != sizeof(auxdata))
  		return FSCACHE_CHECKAUX_OBSOLETE;
  
  	memset(&auxdata, 0, sizeof(auxdata));
  	auxdata.resource_id = tcon->resource_id;
  
  	if (memcmp(data, &auxdata, datalen) != 0)
  		return FSCACHE_CHECKAUX_OBSOLETE;
  
  	return FSCACHE_CHECKAUX_OKAY;
  }
  
  /*
   * Superblock object for FS-Cache
   */
  const struct fscache_cookie_def cifs_fscache_super_index_def = {
  	.name = "CIFS.super",
  	.type = FSCACHE_COOKIE_TYPE_INDEX,
  	.get_key = cifs_super_get_key,
  	.get_aux = cifs_fscache_super_get_aux,
  	.check_aux = cifs_fscache_super_check_aux,
  };
  
  /*
   * Auxiliary data attached to CIFS inode within the cache
   */
  struct cifs_fscache_inode_auxdata {
  	struct timespec	last_write_time;
  	struct timespec	last_change_time;
  	u64		eof;
  };
  
  static uint16_t cifs_fscache_inode_get_key(const void *cookie_netfs_data,
  					   void *buffer, uint16_t maxbuf)
  {
  	const struct cifsInodeInfo *cifsi = cookie_netfs_data;
  	uint16_t keylen;
  
  	/* use the UniqueId as the key */
  	keylen = sizeof(cifsi->uniqueid);
  	if (keylen > maxbuf)
  		keylen = 0;
  	else
  		memcpy(buffer, &cifsi->uniqueid, keylen);
  
  	return keylen;
  }
  
  static void
  cifs_fscache_inode_get_attr(const void *cookie_netfs_data, uint64_t *size)
  {
  	const struct cifsInodeInfo *cifsi = cookie_netfs_data;
  
  	*size = cifsi->vfs_inode.i_size;
  }
  
  static uint16_t
  cifs_fscache_inode_get_aux(const void *cookie_netfs_data, void *buffer,
  			   uint16_t maxbuf)
  {
  	struct cifs_fscache_inode_auxdata auxdata;
  	const struct cifsInodeInfo *cifsi = cookie_netfs_data;
  
  	memset(&auxdata, 0, sizeof(auxdata));
  	auxdata.eof = cifsi->server_eof;
  	auxdata.last_write_time = cifsi->vfs_inode.i_mtime;
  	auxdata.last_change_time = cifsi->vfs_inode.i_ctime;
  
  	if (maxbuf > sizeof(auxdata))
  		maxbuf = sizeof(auxdata);
  
  	memcpy(buffer, &auxdata, maxbuf);
  
  	return maxbuf;
  }
  
  static enum
  fscache_checkaux cifs_fscache_inode_check_aux(void *cookie_netfs_data,
  					      const void *data,
  					      uint16_t datalen)
  {
  	struct cifs_fscache_inode_auxdata auxdata;
  	struct cifsInodeInfo *cifsi = cookie_netfs_data;
  
  	if (datalen != sizeof(auxdata))
  		return FSCACHE_CHECKAUX_OBSOLETE;
  
  	memset(&auxdata, 0, sizeof(auxdata));
  	auxdata.eof = cifsi->server_eof;
  	auxdata.last_write_time = cifsi->vfs_inode.i_mtime;
  	auxdata.last_change_time = cifsi->vfs_inode.i_ctime;
  
  	if (memcmp(data, &auxdata, datalen) != 0)
  		return FSCACHE_CHECKAUX_OBSOLETE;
  
  	return FSCACHE_CHECKAUX_OKAY;
  }
  
  static void cifs_fscache_inode_now_uncached(void *cookie_netfs_data)
  {
  	struct cifsInodeInfo *cifsi = cookie_netfs_data;
  	struct pagevec pvec;
  	pgoff_t first;
  	int loop, nr_pages;
  
  	pagevec_init(&pvec, 0);
  	first = 0;
  
  	cifs_dbg(FYI, "%s: cifs inode 0x%p now uncached
  ", __func__, cifsi);
  
  	for (;;) {
  		nr_pages = pagevec_lookup(&pvec,
  					  cifsi->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();
  	}
  }
  
  const struct fscache_cookie_def cifs_fscache_inode_object_def = {
  	.name		= "CIFS.uniqueid",
  	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
  	.get_key	= cifs_fscache_inode_get_key,
  	.get_attr	= cifs_fscache_inode_get_attr,
  	.get_aux	= cifs_fscache_inode_get_aux,
  	.check_aux	= cifs_fscache_inode_check_aux,
  	.now_uncached	= cifs_fscache_inode_now_uncached,
  };