/* AFS superblock handling
   *

   * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.

   *
   * This software may be freely redistributed under the terms of the
   * GNU General Public License.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   *
   * Authors: David Howells <dhowells@redhat.com>

   *          David Woodhouse <dwmw2@infradead.org>

   *
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/mount.h>

  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/fs.h>
  #include <linux/pagemap.h>

  #include <linux/parser.h>

  #include <linux/statfs.h>

  #include <linux/sched.h>

  #include <linux/nsproxy.h>
  #include <net/net_namespace.h>

  #include "internal.h"
  
  #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */

  static void afs_i_init_once(void *foo);

  static struct dentry *afs_mount(struct file_system_type *fs_type,
  		      int flags, const char *dev_name, void *data);

  static void afs_kill_super(struct super_block *sb);

  static struct inode *afs_alloc_inode(struct super_block *sb);

  static void afs_destroy_inode(struct inode *inode);

  static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);

  static int afs_show_devname(struct seq_file *m, struct dentry *root);
  static int afs_show_options(struct seq_file *m, struct dentry *root);

  struct file_system_type afs_fs_type = {

  	.owner		= THIS_MODULE,
  	.name		= "afs",

  	.mount		= afs_mount,

  	.kill_sb	= afs_kill_super,

  	.fs_flags	= 0,

  };

  MODULE_ALIAS_FS("afs");

  static const struct super_operations afs_super_ops = {

  	.statfs		= afs_statfs,

  	.alloc_inode	= afs_alloc_inode,

  	.drop_inode	= afs_drop_inode,

  	.destroy_inode	= afs_destroy_inode,

  	.evict_inode	= afs_evict_inode,

  	.show_devname	= afs_show_devname,
  	.show_options	= afs_show_options,

  };

  static struct kmem_cache *afs_inode_cachep;

  static atomic_t afs_count_active_inodes;

  enum {
  	afs_no_opt,
  	afs_opt_cell,
  	afs_opt_rwpath,
  	afs_opt_vol,

  	afs_opt_autocell,

  };

  static const match_table_t afs_options_list = {

  	{ afs_opt_cell,		"cell=%s"	},
  	{ afs_opt_rwpath,	"rwpath"	},
  	{ afs_opt_vol,		"vol=%s"	},

  	{ afs_opt_autocell,	"autocell"	},

  	{ afs_no_opt,		NULL		},
  };

  /*
   * initialise the filesystem
   */
  int __init afs_fs_init(void)
  {
  	int ret;
  
  	_enter("");

  	/* create ourselves an inode cache */
  	atomic_set(&afs_count_active_inodes, 0);
  
  	ret = -ENOMEM;
  	afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  					     sizeof(struct afs_vnode),
  					     0,

  					     SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,

  					     afs_i_init_once);

  	if (!afs_inode_cachep) {
  		printk(KERN_NOTICE "kAFS: Failed to allocate inode cache
  ");
  		return ret;
  	}
  
  	/* now export our filesystem to lesser mortals */
  	ret = register_filesystem(&afs_fs_type);
  	if (ret < 0) {
  		kmem_cache_destroy(afs_inode_cachep);

  		_leave(" = %d", ret);

  		return ret;
  	}

  	_leave(" = 0");

  	return 0;

  }

  /*
   * clean up the filesystem
   */
  void __exit afs_fs_exit(void)
  {

  	_enter("");
  
  	afs_mntpt_kill_timer();

  	unregister_filesystem(&afs_fs_type);
  
  	if (atomic_read(&afs_count_active_inodes) != 0) {
  		printk("kAFS: %d active inode objects still present
  ",
  		       atomic_read(&afs_count_active_inodes));
  		BUG();
  	}

  	/*
  	 * Make sure all delayed rcu free inodes are flushed before we
  	 * destroy cache.
  	 */
  	rcu_barrier();

  	kmem_cache_destroy(afs_inode_cachep);

  	_leave("");

  }

  /*

   * Display the mount device name in /proc/mounts.
   */
  static int afs_show_devname(struct seq_file *m, struct dentry *root)
  {
  	struct afs_super_info *as = root->d_sb->s_fs_info;
  	struct afs_volume *volume = as->volume;
  	struct afs_cell *cell = volume->cell;
  	const char *suf = "";
  	char pref = '%';
  
  	switch (volume->type) {
  	case AFSVL_RWVOL:
  		break;
  	case AFSVL_ROVOL:
  		pref = '#';
  		if (volume->type_force)
  			suf = ".readonly";
  		break;
  	case AFSVL_BACKVOL:
  		pref = '#';
  		suf = ".backup";
  		break;
  	}
  
  	seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->vlocation->vldb.name, suf);
  	return 0;
  }
  
  /*
   * Display the mount options in /proc/mounts.
   */
  static int afs_show_options(struct seq_file *m, struct dentry *root)
  {
  	if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
  		seq_puts(m, "autocell");
  	return 0;
  }
  
  /*

   * parse the mount options
   * - this function has been shamelessly adapted from the ext3 fs which
   *   shamelessly adapted it from the msdos fs
   */

  static int afs_parse_options(struct afs_mount_params *params,
  			     char *options, const char **devname)

  {

  	struct afs_cell *cell;

  	substring_t args[MAX_OPT_ARGS];
  	char *p;
  	int token;

  
  	_enter("%s", options);
  
  	options[PAGE_SIZE - 1] = 0;

  	while ((p = strsep(&options, ","))) {
  		if (!*p)
  			continue;

  		token = match_token(p, afs_options_list, args);
  		switch (token) {
  		case afs_opt_cell:
  			cell = afs_cell_lookup(args[0].from,

  					       args[0].to - args[0].from,
  					       false);

  			if (IS_ERR(cell))
  				return PTR_ERR(cell);

  			afs_put_cell(params->cell);
  			params->cell = cell;

  			break;
  
  		case afs_opt_rwpath:
  			params->rwpath = 1;
  			break;
  
  		case afs_opt_vol:
  			*devname = args[0].from;
  			break;

  		case afs_opt_autocell:
  			params->autocell = 1;
  			break;

  		default:
  			printk(KERN_ERR "kAFS:"
  			       " Unknown or invalid mount option: '%s'
  ", p);
  			return -EINVAL;

  		}

  	}

  	_leave(" = 0");
  	return 0;

  }

  /*

   * parse a device name to get cell name, volume name, volume type and R/W
   * selector
   * - this can be one of the following:
   *	"%[cell:]volume[.]"		R/W volume
   *	"#[cell:]volume[.]"		R/O or R/W volume (rwpath=0),
   *					 or R/W (rwpath=1) volume
   *	"%[cell:]volume.readonly"	R/O volume
   *	"#[cell:]volume.readonly"	R/O volume
   *	"%[cell:]volume.backup"		Backup volume
   *	"#[cell:]volume.backup"		Backup volume
   */
  static int afs_parse_device_name(struct afs_mount_params *params,
  				 const char *name)
  {
  	struct afs_cell *cell;
  	const char *cellname, *suffix;
  	int cellnamesz;
  
  	_enter(",%s", name);
  
  	if (!name) {
  		printk(KERN_ERR "kAFS: no volume name specified
  ");
  		return -EINVAL;
  	}
  
  	if ((name[0] != '%' && name[0] != '#') || !name[1]) {
  		printk(KERN_ERR "kAFS: unparsable volume name
  ");
  		return -EINVAL;
  	}
  
  	/* determine the type of volume we're looking for */
  	params->type = AFSVL_ROVOL;
  	params->force = false;
  	if (params->rwpath || name[0] == '%') {
  		params->type = AFSVL_RWVOL;
  		params->force = true;
  	}
  	name++;
  
  	/* split the cell name out if there is one */
  	params->volname = strchr(name, ':');
  	if (params->volname) {
  		cellname = name;
  		cellnamesz = params->volname - name;
  		params->volname++;
  	} else {
  		params->volname = name;
  		cellname = NULL;
  		cellnamesz = 0;
  	}
  
  	/* the volume type is further affected by a possible suffix */
  	suffix = strrchr(params->volname, '.');
  	if (suffix) {
  		if (strcmp(suffix, ".readonly") == 0) {
  			params->type = AFSVL_ROVOL;
  			params->force = true;
  		} else if (strcmp(suffix, ".backup") == 0) {
  			params->type = AFSVL_BACKVOL;
  			params->force = true;
  		} else if (suffix[1] == 0) {
  		} else {
  			suffix = NULL;
  		}
  	}
  
  	params->volnamesz = suffix ?
  		suffix - params->volname : strlen(params->volname);
  
  	_debug("cell %*.*s [%p]",
  	       cellnamesz, cellnamesz, cellname ?: "", params->cell);
  
  	/* lookup the cell record */
  	if (cellname || !params->cell) {

  		cell = afs_cell_lookup(cellname, cellnamesz, true);

  		if (IS_ERR(cell)) {

  			printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'
  ",
  			       cellnamesz, cellnamesz, cellname ?: "");

  			return PTR_ERR(cell);
  		}
  		afs_put_cell(params->cell);
  		params->cell = cell;
  	}
  
  	_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
  	       params->cell->name, params->cell,
  	       params->volnamesz, params->volnamesz, params->volname,
  	       suffix ?: "-", params->type, params->force ? " FORCE" : "");
  
  	return 0;
  }
  
  /*

   * check a superblock to see if it's the one we're looking for
   */
  static int afs_test_super(struct super_block *sb, void *data)
  {

  	struct afs_super_info *as1 = data;

  	struct afs_super_info *as = sb->s_fs_info;

  	return as->volume == as1->volume;
  }
  
  static int afs_set_super(struct super_block *sb, void *data)
  {
  	sb->s_fs_info = data;
  	return set_anon_super(sb, NULL);

  }

  /*
   * fill in the superblock
   */

  static int afs_fill_super(struct super_block *sb,
  			  struct afs_mount_params *params)

  {

  	struct afs_super_info *as = sb->s_fs_info;

  	struct afs_fid fid;

  	struct inode *inode = NULL;
  	int ret;

  	_enter("");

  	/* fill in the superblock */

  	sb->s_blocksize		= PAGE_SIZE;
  	sb->s_blocksize_bits	= PAGE_SHIFT;

  	sb->s_magic		= AFS_FS_MAGIC;
  	sb->s_op		= &afs_super_ops;

  	sb->s_xattr		= afs_xattr_handlers;

  	ret = super_setup_bdi(sb);
  	if (ret)
  		return ret;
  	sb->s_bdi->ra_pages	= VM_MAX_READAHEAD * 1024 / PAGE_SIZE;

  	strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));

  
  	/* allocate the root inode and dentry */
  	fid.vid		= as->volume->vid;
  	fid.vnode	= 1;
  	fid.unique	= 1;

  	inode = afs_iget(sb, params->key, &fid, NULL, NULL);

  	if (IS_ERR(inode))

  		return PTR_ERR(inode);

  	if (params->autocell)
  		set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);

  	ret = -ENOMEM;

  	sb->s_root = d_make_root(inode);
  	if (!sb->s_root)

  		goto error;

  	sb->s_d_op = &afs_fs_dentry_operations;

  	_leave(" = 0");

  	return 0;

  error:

  	_leave(" = %d", ret);

  	return ret;

  }

  /*
   * get an AFS superblock

   */

  static struct dentry *afs_mount(struct file_system_type *fs_type,
  		      int flags, const char *dev_name, void *options)

  {
  	struct afs_mount_params params;
  	struct super_block *sb;

  	struct afs_volume *vol;

  	struct key *key;

  	char *new_opts = kstrdup(options, GFP_KERNEL);

  	struct afs_super_info *as;

  	int ret;
  
  	_enter(",,%s,%p", dev_name, options);
  
  	memset(&params, 0, sizeof(params));

  	ret = -EINVAL;
  	if (current->nsproxy->net_ns != &init_net)
  		goto error;

  	/* parse the options and device name */

  	if (options) {

  		ret = afs_parse_options(&params, options, &dev_name);

  		if (ret < 0)
  			goto error;

  	}

  	ret = afs_parse_device_name(&params, dev_name);
  	if (ret < 0)
  		goto error;
  
  	/* try and do the mount securely */
  	key = afs_request_key(params.cell);
  	if (IS_ERR(key)) {
  		_leave(" = %ld [key]", PTR_ERR(key));
  		ret = PTR_ERR(key);
  		goto error;
  	}
  	params.key = key;

  	/* parse the device name */

  	vol = afs_volume_lookup(&params);

  	if (IS_ERR(vol)) {
  		ret = PTR_ERR(vol);

  		goto error;

  	}

  
  	/* allocate a superblock info record */
  	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
  	if (!as) {
  		ret = -ENOMEM;
  		afs_put_volume(vol);
  		goto error;
  	}
  	as->volume = vol;

  
  	/* allocate a deviceless superblock */

  	sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);

  	if (IS_ERR(sb)) {
  		ret = PTR_ERR(sb);

  		afs_put_volume(vol);
  		kfree(as);

  		goto error;

  	}

  	if (!sb->s_root) {
  		/* initial superblock/root creation */
  		_debug("create");

  		ret = afs_fill_super(sb, &params);
  		if (ret < 0) {

  			deactivate_locked_super(sb);

  			goto error;
  		}
  		sb->s_flags |= MS_ACTIVE;
  	} else {
  		_debug("reuse");
  		ASSERTCMP(sb->s_flags, &, MS_ACTIVE);

  		afs_put_volume(vol);
  		kfree(as);

  	}

  	afs_put_cell(params.cell);

  	kfree(new_opts);

  	_leave(" = 0 [%p]", sb);

  	return dget(sb->s_root);

  error:

  	afs_put_cell(params.cell);
  	key_put(params.key);

  	kfree(new_opts);

  	_leave(" = %d", ret);

  	return ERR_PTR(ret);

  }

  static void afs_kill_super(struct super_block *sb)

  {
  	struct afs_super_info *as = sb->s_fs_info;

  	kill_anon_super(sb);

  	afs_put_volume(as->volume);

  	kfree(as);

  }

  /*
   * initialise an inode cache slab element prior to any use
   */

  static void afs_i_init_once(void *_vnode)

  {

  	struct afs_vnode *vnode = _vnode;

  	memset(vnode, 0, sizeof(*vnode));
  	inode_init_once(&vnode->vfs_inode);
  	init_waitqueue_head(&vnode->update_waitq);
  	mutex_init(&vnode->permits_lock);
  	mutex_init(&vnode->validate_lock);
  	spin_lock_init(&vnode->writeback_lock);
  	spin_lock_init(&vnode->lock);
  	INIT_LIST_HEAD(&vnode->writebacks);

  	INIT_LIST_HEAD(&vnode->pending_locks);
  	INIT_LIST_HEAD(&vnode->granted_locks);
  	INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);

  	INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);

  }

  /*
   * allocate an AFS inode struct from our slab cache
   */
  static struct inode *afs_alloc_inode(struct super_block *sb)
  {
  	struct afs_vnode *vnode;

  	vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);

  	if (!vnode)
  		return NULL;
  
  	atomic_inc(&afs_count_active_inodes);
  
  	memset(&vnode->fid, 0, sizeof(vnode->fid));
  	memset(&vnode->status, 0, sizeof(vnode->status));
  
  	vnode->volume		= NULL;
  	vnode->update_cnt	= 0;

  	vnode->flags		= 1 << AFS_VNODE_UNSET;

  	vnode->cb_promised	= false;

  	_leave(" = %p", &vnode->vfs_inode);

  	return &vnode->vfs_inode;

  }

  static void afs_i_callback(struct rcu_head *head)
  {
  	struct inode *inode = container_of(head, struct inode, i_rcu);
  	struct afs_vnode *vnode = AFS_FS_I(inode);

  	kmem_cache_free(afs_inode_cachep, vnode);
  }

  /*
   * destroy an AFS inode struct
   */
  static void afs_destroy_inode(struct inode *inode)
  {

  	struct afs_vnode *vnode = AFS_FS_I(inode);

  	_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);

  	_debug("DESTROY INODE %p", inode);
  
  	ASSERTCMP(vnode->server, ==, NULL);

  	call_rcu(&inode->i_rcu, afs_i_callback);

  	atomic_dec(&afs_count_active_inodes);

  }

  
  /*
   * return information about an AFS volume
   */
  static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
  {
  	struct afs_volume_status vs;

  	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));

  	struct key *key;
  	int ret;
  
  	key = afs_request_key(vnode->volume->cell);
  	if (IS_ERR(key))
  		return PTR_ERR(key);
  
  	ret = afs_vnode_get_volume_status(vnode, key, &vs);
  	key_put(key);
  	if (ret < 0) {
  		_leave(" = %d", ret);
  		return ret;
  	}
  
  	buf->f_type	= dentry->d_sb->s_magic;
  	buf->f_bsize	= AFS_BLOCK_SIZE;
  	buf->f_namelen	= AFSNAMEMAX - 1;
  
  	if (vs.max_quota == 0)
  		buf->f_blocks = vs.part_max_blocks;
  	else
  		buf->f_blocks = vs.max_quota;
  	buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
  	return 0;
  }