/*
   *  linux/fs/9p/v9fs.c
   *
   *  This file contains functions assisting in mapping VFS to 9P2000
   *

   *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>

   *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   *
   *  This program is free software; you can redistribute it and/or modify

   *  it under the terms of the GNU General Public License version 2
   *  as published by the Free Software Foundation.

   *
   *  This program 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 General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; if not, write to:
   *  Free Software Foundation
   *  51 Franklin Street, Fifth Floor
   *  Boston, MA  02111-1301  USA
   *
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/fs.h>

  #include <linux/sched.h>

  #include <linux/parser.h>
  #include <linux/idr.h>

  #include <linux/slab.h>

  #include <net/9p/9p.h>

  #include <net/9p/client.h>

  #include <net/9p/transport.h>

  #include "v9fs.h"

  #include "v9fs_vfs.h"

  #include "cache.h"
  
  static DEFINE_SPINLOCK(v9fs_sessionlist_lock);
  static LIST_HEAD(v9fs_sessionlist);

  struct kmem_cache *v9fs_inode_cache;

  
  /*

   * Option Parsing (code inspired by NFS code)
   *  NOTE: each transport will parse its own options
   */

  
  enum {
  	/* Options that take integer arguments */

  	Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid,

  	/* String options */

  	Opt_uname, Opt_remotename, Opt_trans, Opt_cache, Opt_cachetag,

  	/* Options that take no arguments */

  	Opt_nodevmap,

  	/* Cache options */

  	Opt_cache_loose, Opt_fscache,

  	/* Access options */

  	Opt_access, Opt_posixacl,

  	/* Error token */
  	Opt_err
  };

  static const match_table_t tokens = {

  	{Opt_debug, "debug=%x"},

  	{Opt_dfltuid, "dfltuid=%u"},
  	{Opt_dfltgid, "dfltgid=%u"},

  	{Opt_afid, "afid=%u"},

  	{Opt_uname, "uname=%s"},

  	{Opt_remotename, "aname=%s"},

  	{Opt_nodevmap, "nodevmap"},

  	{Opt_cache, "cache=%s"},

  	{Opt_cache_loose, "loose"},

  	{Opt_fscache, "fscache"},
  	{Opt_cachetag, "cachetag=%s"},

  	{Opt_access, "access=%s"},

  	{Opt_posixacl, "posixacl"},

  	{Opt_err, NULL}
  };

  /* Interpret mount options for cache mode */
  static int get_cache_mode(char *s)
  {
  	int version = -EINVAL;
  
  	if (!strcmp(s, "loose")) {
  		version = CACHE_LOOSE;

  		p9_debug(P9_DEBUG_9P, "Cache mode: loose
  ");

  	} else if (!strcmp(s, "fscache")) {
  		version = CACHE_FSCACHE;

  		p9_debug(P9_DEBUG_9P, "Cache mode: fscache
  ");

  	} else if (!strcmp(s, "none")) {
  		version = CACHE_NONE;

  		p9_debug(P9_DEBUG_9P, "Cache mode: none
  ");

  	} else

  		pr_info("Unknown Cache mode %s
  ", s);

  	return version;
  }

  /**
   * v9fs_parse_options - parse mount options into session structure

   * @v9ses: existing v9fs session information
   *

   * Return 0 upon success, -ERRNO upon failure.

   */

  static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)

  {

  	char *options, *tmp_options;

  	substring_t args[MAX_OPT_ARGS];

  	char *p;

  	int option = 0;

  	char *s, *e;

  	int ret = 0;

  
  	/* setup defaults */

  	v9ses->afid = ~0;
  	v9ses->debug = 0;

  	v9ses->cache = CACHE_NONE;

  #ifdef CONFIG_9P_FSCACHE
  	v9ses->cachetag = NULL;
  #endif

  	if (!opts)

  		return 0;

  	tmp_options = kstrdup(opts, GFP_KERNEL);

  	if (!tmp_options) {
  		ret = -ENOMEM;

  		goto fail_option_alloc;

  	}

  	options = tmp_options;

  	while ((p = strsep(&options, ",")) != NULL) {

  		int token, r;

  		if (!*p)
  			continue;
  		token = match_token(p, tokens, args);

  		switch (token) {
  		case Opt_debug:
  			r = match_int(&args[0], &option);

  			if (r < 0) {

  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?
  ");

  				ret = r;

  				continue;
  			}

  			v9ses->debug = option;

  #ifdef CONFIG_NET_9P_DEBUG

  			p9_debug_level = option;

  #endif

  			break;

  		case Opt_dfltuid:

  			r = match_int(&args[0], &option);
  			if (r < 0) {

  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?
  ");

  				ret = r;
  				continue;
  			}

  			v9ses->dfltuid = option;

  			break;

  		case Opt_dfltgid:

  			r = match_int(&args[0], &option);
  			if (r < 0) {

  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?
  ");

  				ret = r;
  				continue;
  			}

  			v9ses->dfltgid = option;

  			break;
  		case Opt_afid:

  			r = match_int(&args[0], &option);
  			if (r < 0) {

  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?
  ");

  				ret = r;
  				continue;
  			}

  			v9ses->afid = option;
  			break;

  		case Opt_uname:

  			match_strlcpy(v9ses->uname, &args[0], PATH_MAX);

  			break;
  		case Opt_remotename:

  			match_strlcpy(v9ses->aname, &args[0], PATH_MAX);

  			break;

  		case Opt_nodevmap:
  			v9ses->nodev = 1;
  			break;

  		case Opt_cache_loose:
  			v9ses->cache = CACHE_LOOSE;
  			break;

  		case Opt_fscache:
  			v9ses->cache = CACHE_FSCACHE;
  			break;
  		case Opt_cachetag:
  #ifdef CONFIG_9P_FSCACHE
  			v9ses->cachetag = match_strdup(&args[0]);
  #endif
  			break;
  		case Opt_cache:
  			s = match_strdup(&args[0]);

  			if (!s) {
  				ret = -ENOMEM;

  				p9_debug(P9_DEBUG_ERROR,
  					 "problem allocating copy of cache arg
  ");

  				goto free_and_return;
  			}

  			ret = get_cache_mode(s);
  			if (ret == -EINVAL) {
  				kfree(s);
  				goto free_and_return;
  			}

  			v9ses->cache = ret;

  			kfree(s);
  			break;

  
  		case Opt_access:
  			s = match_strdup(&args[0]);

  			if (!s) {
  				ret = -ENOMEM;

  				p9_debug(P9_DEBUG_ERROR,
  					 "problem allocating copy of access arg
  ");

  				goto free_and_return;
  			}

  			v9ses->flags &= ~V9FS_ACCESS_MASK;
  			if (strcmp(s, "user") == 0)
  				v9ses->flags |= V9FS_ACCESS_USER;
  			else if (strcmp(s, "any") == 0)
  				v9ses->flags |= V9FS_ACCESS_ANY;

  			else if (strcmp(s, "client") == 0) {

  				v9ses->flags |= V9FS_ACCESS_CLIENT;

  			} else {

  				v9ses->flags |= V9FS_ACCESS_SINGLE;

  				v9ses->uid = simple_strtoul(s, &e, 10);

  				if (*e != '\0') {
  					ret = -EINVAL;

  					pr_info("Unknown access argument %s
  ",
  						s);

  					kfree(s);
  					goto free_and_return;
  				}

  			}

  			kfree(s);

  			break;

  		case Opt_posixacl:
  #ifdef CONFIG_9P_FS_POSIX_ACL
  			v9ses->flags |= V9FS_POSIX_ACL;
  #else

  			p9_debug(P9_DEBUG_ERROR,
  				 "Not defined CONFIG_9P_FS_POSIX_ACL. Ignoring posixacl option
  ");

  #endif
  			break;

  		default:
  			continue;
  		}
  	}

  free_and_return:

  	kfree(tmp_options);

  fail_option_alloc:

  	return ret;

  }
  
  /**

   * v9fs_session_init - initialize session
   * @v9ses: session information structure
   * @dev_name: device being mounted
   * @data: options
   *
   */

  struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,

  		  const char *dev_name, char *data)
  {

  	int retval = -EINVAL;

  	struct p9_fid *fid;

  	int rc;

  	v9ses->uname = __getname();
  	if (!v9ses->uname)

  		return ERR_PTR(-ENOMEM);

  	v9ses->aname = __getname();
  	if (!v9ses->aname) {
  		__putname(v9ses->uname);

  		return ERR_PTR(-ENOMEM);

  	}

  	init_rwsem(&v9ses->rename_sem);

  	rc = bdi_setup_and_register(&v9ses->bdi, "9p", BDI_CAP_MAP_COPY);
  	if (rc) {
  		__putname(v9ses->aname);
  		__putname(v9ses->uname);
  		return ERR_PTR(rc);
  	}

  	spin_lock(&v9fs_sessionlist_lock);
  	list_add(&v9ses->slist, &v9fs_sessionlist);
  	spin_unlock(&v9fs_sessionlist_lock);

  	strcpy(v9ses->uname, V9FS_DEFUSER);
  	strcpy(v9ses->aname, V9FS_DEFANAME);
  	v9ses->uid = ~0;

  	v9ses->dfltuid = V9FS_DEFUID;
  	v9ses->dfltgid = V9FS_DEFGID;

  	v9ses->clnt = p9_client_create(dev_name, data);

  	if (IS_ERR(v9ses->clnt)) {
  		retval = PTR_ERR(v9ses->clnt);
  		v9ses->clnt = NULL;

  		p9_debug(P9_DEBUG_ERROR, "problem initializing 9p client
  ");

  		goto error;

  	}

  	v9ses->flags = V9FS_ACCESS_USER;
  
  	if (p9_is_proto_dotl(v9ses->clnt)) {
  		v9ses->flags = V9FS_ACCESS_CLIENT;

  		v9ses->flags |= V9FS_PROTO_2000L;

  	} else if (p9_is_proto_dotu(v9ses->clnt)) {

  		v9ses->flags |= V9FS_PROTO_2000U;

  	}
  
  	rc = v9fs_parse_options(v9ses, data);
  	if (rc < 0) {
  		retval = rc;
  		goto error;
  	}

  	v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;

  	if (!v9fs_proto_dotl(v9ses) &&
  	    ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
  		/*
  		 * We support ACCESS_CLIENT only for dotl.
  		 * Fall back to ACCESS_USER
  		 */
  		v9ses->flags &= ~V9FS_ACCESS_MASK;
  		v9ses->flags |= V9FS_ACCESS_USER;
  	}
  	/*FIXME !! */

  	/* for legacy mode, fall back to V9FS_ACCESS_ANY */

  	if (!(v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) &&

  		((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {
  
  		v9ses->flags &= ~V9FS_ACCESS_MASK;
  		v9ses->flags |= V9FS_ACCESS_ANY;
  		v9ses->uid = ~0;
  	}

  	if (!v9fs_proto_dotl(v9ses) ||
  		!((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
  		/*
  		 * We support ACL checks on clinet only if the protocol is
  		 * 9P2000.L and access is V9FS_ACCESS_CLIENT.
  		 */
  		v9ses->flags &= ~V9FS_ACL_MASK;
  	}

  
  	fid = p9_client_attach(v9ses->clnt, NULL, v9ses->uname, ~0,
  							v9ses->aname);

  	if (IS_ERR(fid)) {
  		retval = PTR_ERR(fid);
  		fid = NULL;

  		p9_debug(P9_DEBUG_ERROR, "cannot attach
  ");

  		goto error;

  	}

  	if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
  		fid->uid = v9ses->uid;
  	else
  		fid->uid = ~0;

  #ifdef CONFIG_9P_FSCACHE
  	/* register the session for caching */
  	v9fs_cache_session_get_cookie(v9ses);
  #endif

  	return fid;

  error:

  	bdi_destroy(&v9ses->bdi);

  	return ERR_PTR(retval);

  }
  
  /**
   * v9fs_session_close - shutdown a session
   * @v9ses: session information structure
   *
   */
  
  void v9fs_session_close(struct v9fs_session_info *v9ses)
  {

  	if (v9ses->clnt) {
  		p9_client_destroy(v9ses->clnt);
  		v9ses->clnt = NULL;

  	}

  #ifdef CONFIG_9P_FSCACHE
  	if (v9ses->fscache) {
  		v9fs_cache_session_put_cookie(v9ses);
  		kfree(v9ses->cachetag);
  	}
  #endif

  	__putname(v9ses->uname);
  	__putname(v9ses->aname);

  	bdi_destroy(&v9ses->bdi);

  	spin_lock(&v9fs_sessionlist_lock);
  	list_del(&v9ses->slist);
  	spin_unlock(&v9fs_sessionlist_lock);

  }

  /**

   * v9fs_session_cancel - terminate a session
   * @v9ses: session to terminate
   *
   * mark transport as disconnected and cancel all pending requests.

   */

  void v9fs_session_cancel(struct v9fs_session_info *v9ses) {

  	p9_debug(P9_DEBUG_ERROR, "cancel session %p
  ", v9ses);

  	p9_client_disconnect(v9ses->clnt);

  }

  /**
   * v9fs_session_begin_cancel - Begin terminate of a session
   * @v9ses: session to terminate
   *
   * After this call we don't allow any request other than clunk.
   */
  
  void v9fs_session_begin_cancel(struct v9fs_session_info *v9ses)
  {

  	p9_debug(P9_DEBUG_ERROR, "begin cancel session %p
  ", v9ses);

  	p9_client_begin_disconnect(v9ses->clnt);
  }

  extern int v9fs_error_init(void);

  static struct kobject *v9fs_kobj;
  
  #ifdef CONFIG_9P_FSCACHE

  /**

   * caches_show - list caches associated with a session
   *
   * Returns the size of buffer written.
   */
  
  static ssize_t caches_show(struct kobject *kobj,
  			   struct kobj_attribute *attr,
  			   char *buf)
  {
  	ssize_t n = 0, count = 0, limit = PAGE_SIZE;
  	struct v9fs_session_info *v9ses;
  
  	spin_lock(&v9fs_sessionlist_lock);
  	list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
  		if (v9ses->cachetag) {
  			n = snprintf(buf, limit, "%s
  ", v9ses->cachetag);
  			if (n < 0) {
  				count = n;
  				break;
  			}
  
  			count += n;
  			limit -= n;
  		}
  	}
  
  	spin_unlock(&v9fs_sessionlist_lock);
  	return count;
  }
  
  static struct kobj_attribute v9fs_attr_cache = __ATTR_RO(caches);
  #endif /* CONFIG_9P_FSCACHE */
  
  static struct attribute *v9fs_attrs[] = {
  #ifdef CONFIG_9P_FSCACHE
  	&v9fs_attr_cache.attr,
  #endif
  	NULL,
  };
  
  static struct attribute_group v9fs_attr_group = {
  	.attrs = v9fs_attrs,
  };
  
  /**
   * v9fs_sysfs_init - Initialize the v9fs sysfs interface
   *
   */
  
  static int v9fs_sysfs_init(void)
  {
  	v9fs_kobj = kobject_create_and_add("9p", fs_kobj);
  	if (!v9fs_kobj)
  		return -ENOMEM;
  
  	if (sysfs_create_group(v9fs_kobj, &v9fs_attr_group)) {
  		kobject_put(v9fs_kobj);
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  /**
   * v9fs_sysfs_cleanup - Unregister the v9fs sysfs interface
   *
   */
  
  static void v9fs_sysfs_cleanup(void)
  {
  	sysfs_remove_group(v9fs_kobj, &v9fs_attr_group);
  	kobject_put(v9fs_kobj);
  }

  static void v9fs_inode_init_once(void *foo)
  {
  	struct v9fs_inode *v9inode = (struct v9fs_inode *)foo;
  #ifdef CONFIG_9P_FSCACHE
  	v9inode->fscache = NULL;

  #endif

  	memset(&v9inode->qid, 0, sizeof(v9inode->qid));

  	inode_init_once(&v9inode->vfs_inode);
  }
  
  /**
   * v9fs_init_inode_cache - initialize a cache for 9P
   * Returns 0 on success.
   */
  static int v9fs_init_inode_cache(void)
  {
  	v9fs_inode_cache = kmem_cache_create("v9fs_inode_cache",
  					  sizeof(struct v9fs_inode),
  					  0, (SLAB_RECLAIM_ACCOUNT|
  					      SLAB_MEM_SPREAD),
  					  v9fs_inode_init_once);
  	if (!v9fs_inode_cache)
  		return -ENOMEM;
  
  	return 0;
  }
  
  /**
   * v9fs_destroy_inode_cache - destroy the cache of 9P inode
   *
   */
  static void v9fs_destroy_inode_cache(void)
  {
  	kmem_cache_destroy(v9fs_inode_cache);
  }
  
  static int v9fs_cache_register(void)
  {
  	int ret;
  	ret = v9fs_init_inode_cache();
  	if (ret < 0)
  		return ret;
  #ifdef CONFIG_9P_FSCACHE
  	return fscache_register_netfs(&v9fs_cache_netfs);
  #else
  	return ret;
  #endif
  }
  
  static void v9fs_cache_unregister(void)
  {
  	v9fs_destroy_inode_cache();
  #ifdef CONFIG_9P_FSCACHE
  	fscache_unregister_netfs(&v9fs_cache_netfs);
  #endif
  }

  /**
   * init_v9fs - Initialize module

   *
   */
  
  static int __init init_v9fs(void)
  {

  	int err;

  	pr_info("Installing v9fs 9p2000 file system support
  ");

  	/* TODO: Setup list of registered trasnport modules */

  	err = register_filesystem(&v9fs_fs_type);
  	if (err < 0) {

  		pr_err("Failed to register filesystem
  ");

  		return err;
  	}
  
  	err = v9fs_cache_register();
  	if (err < 0) {

  		pr_err("Failed to register v9fs for caching
  ");

  		goto out_fs_unreg;
  	}
  
  	err = v9fs_sysfs_init();
  	if (err < 0) {

  		pr_err("Failed to register with sysfs
  ");

  		goto out_sysfs_cleanup;
  	}
  
  	return 0;
  
  out_sysfs_cleanup:
  	v9fs_sysfs_cleanup();
  
  out_fs_unreg:
  	unregister_filesystem(&v9fs_fs_type);
  
  	return err;

  }
  
  /**

   * exit_v9fs - shutdown module

   *
   */
  
  static void __exit exit_v9fs(void)
  {

  	v9fs_sysfs_cleanup();
  	v9fs_cache_unregister();

  	unregister_filesystem(&v9fs_fs_type);
  }
  
  module_init(init_v9fs)
  module_exit(exit_v9fs)

  MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");

  MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
  MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
  MODULE_LICENSE("GPL");