/*
   * linux/fs/lockd/svcsubs.c
   *
   * Various support routines for the NLM server.
   *
   * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   */

  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/time.h>
  #include <linux/in.h>

  #include <linux/slab.h>

  #include <linux/mutex.h>

  #include <linux/sunrpc/svc.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/nfsd/nfsfh.h>
  #include <linux/nfsd/export.h>
  #include <linux/lockd/lockd.h>
  #include <linux/lockd/share.h>

  #include <linux/module.h>
  #include <linux/mount.h>

  
  #define NLMDBG_FACILITY		NLMDBG_SVCSUBS
  
  
  /*
   * Global file hash table
   */

  #define FILE_HASH_BITS		7

  #define FILE_NRHASH		(1<<FILE_HASH_BITS)

  static struct hlist_head	nlm_files[FILE_NRHASH];

  static DEFINE_MUTEX(nlm_file_mutex);

  #ifdef NFSD_DEBUG
  static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
  {
  	u32 *fhp = (u32*)f->data;
  
  	/* print the first 32 bytes of the fh */
  	dprintk("lockd: %s (%08x %08x %08x %08x %08x %08x %08x %08x)
  ",
  		msg, fhp[0], fhp[1], fhp[2], fhp[3],
  		fhp[4], fhp[5], fhp[6], fhp[7]);
  }
  
  static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
  {

  	struct inode *inode = file->f_file->f_path.dentry->d_inode;

  
  	dprintk("lockd: %s %s/%ld
  ",
  		msg, inode->i_sb->s_id, inode->i_ino);
  }
  #else
  static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
  {
  	return;
  }
  
  static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
  {
  	return;
  }
  #endif

  static inline unsigned int file_hash(struct nfs_fh *f)
  {
  	unsigned int tmp=0;
  	int i;
  	for (i=0; i<NFS2_FHSIZE;i++)
  		tmp += f->data[i];
  	return tmp & (FILE_NRHASH - 1);
  }
  
  /*
   * Lookup file info. If it doesn't exist, create a file info struct
   * and open a (VFS) file for the given inode.
   *
   * FIXME:
   * Note that we open the file O_RDONLY even when creating write locks.
   * This is not quite right, but for now, we assume the client performs
   * the proper R/W checking.
   */

  __be32

  nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
  					struct nfs_fh *f)
  {

  	struct hlist_node *pos;

  	struct nlm_file	*file;
  	unsigned int	hash;

  	__be32		nfserr;

  	nlm_debug_print_fh("nlm_lookup_file", f);

  
  	hash = file_hash(f);
  
  	/* Lock file table */

  	mutex_lock(&nlm_file_mutex);

  	hlist_for_each_entry(file, pos, &nlm_files[hash], f_list)

  		if (!nfs_compare_fh(&file->f_handle, f))
  			goto found;

  	nlm_debug_print_fh("creating file for", f);

  
  	nfserr = nlm_lck_denied_nolocks;

  	file = kzalloc(sizeof(*file), GFP_KERNEL);

  	if (!file)
  		goto out_unlock;

  	memcpy(&file->f_handle, f, sizeof(struct nfs_fh));

  	mutex_init(&file->f_mutex);

  	INIT_HLIST_NODE(&file->f_list);

  	INIT_LIST_HEAD(&file->f_blocks);

  
  	/* Open the file. Note that this must not sleep for too long, else
  	 * we would lock up lockd:-) So no NFS re-exports, folks.
  	 *
  	 * We have to make sure we have the right credential to open
  	 * the file.
  	 */
  	if ((nfserr = nlmsvc_ops->fopen(rqstp, f, &file->f_file)) != 0) {

  		dprintk("lockd: open failed (error %d)
  ", nfserr);

  		goto out_free;
  	}

  	hlist_add_head(&file->f_list, &nlm_files[hash]);

  
  found:
  	dprintk("lockd: found file %p (count %d)
  ", file, file->f_count);
  	*result = file;
  	file->f_count++;
  	nfserr = 0;
  
  out_unlock:

  	mutex_unlock(&nlm_file_mutex);

  	return nfserr;
  
  out_free:
  	kfree(file);

  	goto out_unlock;
  }
  
  /*
   * Delete a file after having released all locks, blocks and shares
   */
  static inline void
  nlm_delete_file(struct nlm_file *file)
  {

  	nlm_debug_print_file("closing file", file);

  	if (!hlist_unhashed(&file->f_list)) {
  		hlist_del(&file->f_list);
  		nlmsvc_ops->fclose(file->f_file);
  		kfree(file);
  	} else {
  		printk(KERN_WARNING "lockd: attempt to release unknown file!
  ");

  	}

  }
  
  /*
   * Loop over all locks on the given file and perform the specified
   * action.
   */
  static int

  nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
  			nlm_host_match_fn_t match)

  {
  	struct inode	 *inode = nlmsvc_file_inode(file);
  	struct file_lock *fl;
  	struct nlm_host	 *lockhost;
  
  again:
  	file->f_locks = 0;

  	lock_flocks(); /* protects i_flock list */

  	for (fl = inode->i_flock; fl; fl = fl->fl_next) {

  		if (fl->fl_lmops != &nlmsvc_lock_operations)

  			continue;
  
  		/* update current lock count */
  		file->f_locks++;

  		lockhost = (struct nlm_host *) fl->fl_owner;

  		if (match(lockhost, host)) {

  			struct file_lock lock = *fl;

  			unlock_flocks();

  			lock.fl_type  = F_UNLCK;
  			lock.fl_start = 0;
  			lock.fl_end   = OFFSET_MAX;

  			if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {

  				printk("lockd: unlock failure in %s:%d
  ",
  						__FILE__, __LINE__);
  				return 1;
  			}
  			goto again;
  		}
  	}

  	unlock_flocks();

  
  	return 0;
  }

  static int
  nlmsvc_always_match(void *dummy1, struct nlm_host *dummy2)
  {
  	return 1;
  }

  /*

   * Inspect a single file
   */
  static inline int
  nlm_inspect_file(struct nlm_host *host, struct nlm_file *file, nlm_host_match_fn_t match)
  {
  	nlmsvc_traverse_blocks(host, file, match);
  	nlmsvc_traverse_shares(host, file, match);
  	return nlm_traverse_locks(host, file, match);
  }
  
  /*
   * Quick check whether there are still any locks, blocks or
   * shares on a given file.

   */
  static inline int

  nlm_file_inuse(struct nlm_file *file)

  {

  	struct inode	 *inode = nlmsvc_file_inode(file);
  	struct file_lock *fl;
  
  	if (file->f_count || !list_empty(&file->f_blocks) || file->f_shares)
  		return 1;

  	lock_flocks();

  	for (fl = inode->i_flock; fl; fl = fl->fl_next) {

  		if (fl->fl_lmops == &nlmsvc_lock_operations) {
  			unlock_flocks();

  			return 1;

  		}

  	}

  	unlock_flocks();

  	file->f_locks = 0;
  	return 0;

  }
  
  /*
   * Loop over all files in the file table.
   */
  static int

  nlm_traverse_files(void *data, nlm_host_match_fn_t match,
  		int (*is_failover_file)(void *data, struct nlm_file *file))

  {

  	struct hlist_node *pos, *next;
  	struct nlm_file	*file;

  	int i, ret = 0;

  	mutex_lock(&nlm_file_mutex);

  	for (i = 0; i < FILE_NRHASH; i++) {

  		hlist_for_each_entry_safe(file, pos, next, &nlm_files[i], f_list) {

  			if (is_failover_file && !is_failover_file(data, file))
  				continue;

  			file->f_count++;
  			mutex_unlock(&nlm_file_mutex);

  			/* Traverse locks, blocks and shares of this file
  			 * and update file->f_locks count */

  			if (nlm_inspect_file(data, file, match))

  				ret = 1;

  			mutex_lock(&nlm_file_mutex);
  			file->f_count--;

  			/* No more references to this file. Let go of it. */

  			if (list_empty(&file->f_blocks) && !file->f_locks

  			 && !file->f_shares && !file->f_count) {

  				hlist_del(&file->f_list);

  				nlmsvc_ops->fclose(file->f_file);
  				kfree(file);

  			}
  		}
  	}

  	mutex_unlock(&nlm_file_mutex);

  	return ret;

  }
  
  /*
   * Release file. If there are no more remote locks on this file,
   * close it and free the handle.
   *
   * Note that we can't do proper reference counting without major
   * contortions because the code in fs/locks.c creates, deletes and
   * splits locks without notification. Our only way is to walk the
   * entire lock list each time we remove a lock.
   */
  void
  nlm_release_file(struct nlm_file *file)
  {
  	dprintk("lockd: nlm_release_file(%p, ct = %d)
  ",
  				file, file->f_count);
  
  	/* Lock file table */

  	mutex_lock(&nlm_file_mutex);

  
  	/* If there are no more locks etc, delete the file */

  	if (--file->f_count == 0 && !nlm_file_inuse(file))
  		nlm_delete_file(file);

  	mutex_unlock(&nlm_file_mutex);

  }
  
  /*

   * Helpers function for resource traversal
   *
   * nlmsvc_mark_host:
   *	used by the garbage collector; simply sets h_inuse.
   *	Always returns 0.
   *
   * nlmsvc_same_host:
   *	returns 1 iff the two hosts match. Used to release
   *	all resources bound to a specific host.
   *
   * nlmsvc_is_client:
   *	returns 1 iff the host is a client.
   *	Used by nlmsvc_invalidate_all
   */
  static int

  nlmsvc_mark_host(void *data, struct nlm_host *dummy)

  {

  	struct nlm_host *host = data;

  	host->h_inuse = 1;
  	return 0;
  }
  
  static int

  nlmsvc_same_host(void *data, struct nlm_host *other)

  {

  	struct nlm_host *host = data;

  	return host == other;
  }
  
  static int

  nlmsvc_is_client(void *data, struct nlm_host *dummy)

  {

  	struct nlm_host *host = data;

  	if (host->h_server) {
  		/* we are destroying locks even though the client
  		 * hasn't asked us too, so don't unmonitor the
  		 * client
  		 */
  		if (host->h_nsmhandle)
  			host->h_nsmhandle->sm_sticky = 1;
  		return 1;
  	} else
  		return 0;

  }
  
  /*

   * Mark all hosts that still hold resources
   */
  void
  nlmsvc_mark_resources(void)
  {
  	dprintk("lockd: nlmsvc_mark_resources
  ");

  	nlm_traverse_files(NULL, nlmsvc_mark_host, NULL);

  }
  
  /*
   * Release all resources held by the given client
   */
  void
  nlmsvc_free_host_resources(struct nlm_host *host)
  {
  	dprintk("lockd: nlmsvc_free_host_resources
  ");

  	if (nlm_traverse_files(host, nlmsvc_same_host, NULL)) {

  		printk(KERN_WARNING

  			"lockd: couldn't remove all locks held by %s
  ",

  			host->h_name);

  		BUG();
  	}

  }

  /**
   * nlmsvc_invalidate_all - remove all locks held for clients
   *
   * Release all locks held by NFS clients.
   *

   */
  void
  nlmsvc_invalidate_all(void)
  {

  	/*

  	 * Previously, the code would call
  	 * nlmsvc_free_host_resources for each client in
  	 * turn, which is about as inefficient as it gets.
  	 * Now we just do it once in nlm_traverse_files.
  	 */

  	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
  }
  
  static int
  nlmsvc_match_sb(void *datap, struct nlm_file *file)
  {
  	struct super_block *sb = datap;

  	return sb == file->f_file->f_path.dentry->d_sb;

  }

  /**
   * nlmsvc_unlock_all_by_sb - release locks held on this file system
   * @sb: super block
   *
   * Release all locks held by clients accessing this file system.
   */

  int
  nlmsvc_unlock_all_by_sb(struct super_block *sb)
  {
  	int ret;
  
  	ret = nlm_traverse_files(sb, nlmsvc_always_match, nlmsvc_match_sb);
  	return ret ? -EIO : 0;

  }

  EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_sb);

  
  static int
  nlmsvc_match_ip(void *datap, struct nlm_host *host)
  {

  	return rpc_cmp_addr(nlm_srcaddr(host), datap);

  }

  /**
   * nlmsvc_unlock_all_by_ip - release local locks by IP address
   * @server_addr: server's IP address as seen by clients
   *
   * Release all locks held by clients accessing this host
   * via the passed in IP address.
   */

  int

  nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr)

  {
  	int ret;

  	ret = nlm_traverse_files(server_addr, nlmsvc_match_ip, NULL);
  	return ret ? -EIO : 0;

  }
  EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_ip);