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/*

 * Project: HARTIK (HA-rd R-eal TI-me K-ernel)

 *

 * Coordinators: Giorgio Buttazzo <giorgio@sssup.it>

 *               Gerardo Lamastra <gerardo@sssup.it>

 *

 * Authors     : Massimiliano Giorgi <massy@hartik.sssup.it>

 * (see authors.txt for full list of hartik's authors)

 *

 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)

 *

 * http://www.sssup.it

 * http://retis.sssup.it

 * http://hartik.sssup.it

 */

/*

 * Copyright (C) 2000 Massimiliano Giorgi

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * 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 the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 */

/*

 * CVS :        $Id: fs.h,v 1.2 2002-11-11 08:40:44 pj Exp $

 *

 * File:        $File$

 * Revision:    $Revision: 1.2 $

 * Last update: $Date: 2002-11-11 08:40:44 $

 */

/***

 This file contains the registration functions for filesystems mudules and the blocking functions

 used internally for filesystem primitive calls.

 ***/

#ifndef __FS_H__

#define __FS_H__

#include <fs/types.h>

#include <fs/mount.h>

#include <time.h>

#include "mutex.h"

#include "semaph.h"

struct super_block;

/*+

 This structure is used to inform the file system manager that a new

 filesystem is ready to bind data on some device:

 name

   It's the name of the filesystem; can be any string.

 fs_flags

   I don't remember what it is

 fs_ind

   It's a unique identifier for the filesystem; it is taken from the

   PC IBM hard disk architecture

 read_super

   It's the main entry point to the fileystem: the mount function call

   this routine to perform the initial binding between a disk device and

   a filesystem; the struct super_block it is the only thing that

   the filesystem manager required to perform a disk operation.

 +*/

struct file_system_type {

  /*+ filesystem name +*/

  const char *name;

  /*+ filesystem flags +*/

  int        fs_flags;

  /*+ filesystem indicator +*/

  __uint8_t  fs_ind;

  /*+ filesystem read_super function +*/

  struct super_block *(*read_super)(__dev_t device, __uint8_t fs_ind,

                                    struct mount_opts *options);

};

int filesystem_register(struct file_system_type *ptr);

struct file_system_type *filesystem_find_byid(__uint8_t fs_ind);

int mount_device(__dev_t device, __uint8_t fs_ind, char *pathname,

                 struct mount_opts *opts);

int umount_device(__dev_t device);

/*

 *

 *

 *

 */

/* define this if you want to debug the synchronization functions */

#define FS_DEBUGSYNC KERN_DEBUG

#undef FS_DEBUGSYNC

#ifdef FS_DEBUGSYNC

#define _printk0(fmt,args...) cprintf(fmt,##args)

#else

#define _printk0(fmt,args...)

#endif

/*+ state of the fs: 0 can accept syscalls - 1 abort all syscalls +*/

extern int              fssysstate;

/*+ number of syscalls in progress +*/

extern long             fssyscounter;

/*+ mutex to update the above two variables +*/

extern __fs_fastmutex_t fssysmutex;

/*+ syncronization semaphore to change fssysstate +*/

extern __fs_sem_t       fssyssync;

/*+ number of task waiting for fs +*/

extern long             fssysinitcounter;

/*+ syncronization semaphore to change fssysstate from -1 to 0 +*/

extern __fs_sem_t       fssysinit;

/*+ prolog for all syscalls +*/

static __inline__ int __call_to_fs(void)

{

  __fs_fastmutex_lock(&fssysmutex);

  if (fssysstate!=0) {

    __fs_fastmutex_unlock(&fssysmutex);

    return -1;

  }

  fssyscounter++;

  __fs_fastmutex_unlock(&fssysmutex);

  return 0;

}

#define call_to_fs() { if (__call_to_fs()) return -ENOENT; }

/*+ release temporally a syscall (very dangerous) +*/

static __inline__ void release_sys_call(void)

{

  __fs_fastmutex_lock(&fssysmutex);

  fssyscounter--;

  __fs_fastmutex_unlock(&fssysmutex);

}

/*+ reaquire a syscall (MUST be tested the return value for abort) +*/

static __inline__ int reacquire_sys_call(void)

{

  int ret=0;

  __fs_fastmutex_lock(&fssysmutex);

  if (fssysstate==1) ret=-1;

  else fssyscounter++;

  __fs_fastmutex_unlock(&fssysmutex);

  return ret;

}

/*+ epilog for all syscalls +*/

static __inline__ int __return_from_fs(int code)

{

  __fs_fastmutex_lock(&fssysmutex);

  fssyscounter--;

  if (fssysstate==1) {

    if (fssyscounter==0) {

      __fs_fastmutex_unlock(&fssysmutex);

      __fs_sem_signal(&fssyssync);

      return (code);

    }

  }

  __fs_fastmutex_unlock(&fssysmutex);

  return (code);

}

#define return_from_fs(code) return __return_from_fs(code)

#define fs_test_cancellation(code) \

{  \

  if (proc_table[exec_shadow].control & KILL_ENABLED && \

      proc_table[exec_shadow].control & KILL_REQUEST ) { \

    __return_from_fs(0); \

    task_testcancel(); \

    return (code); \

  } \

}

/*+ called only one time when the system is ready +*/

static __inline__ void permit_all_fs_calls(void)

{

  _printk0("<pfscall>");

  __fs_fastmutex_lock(&fssysmutex);

  fssysstate=0;

  if (fssysinitcounter>0) {

    __fs_fastmutex_unlock(&fssysmutex);

    _printk0("<pfscall:%li>",fssysinitcounter);

    while (fssysinitcounter-->0)

      __fs_sem_signal(&fssysinit);

    return;

  }

  __fs_fastmutex_unlock(&fssysmutex);

}

#define SHUTDOWNTIMEOUT 6000000

#define SHUTDOWNSLICE    250000

#define SHUTDOWNCOUNTER (SHUTDOWNTIMEOUT/SHUTDOWNSLICE)

/*+ called only one during shutdown to disable syscalls +*/

static __inline__ void block_all_fs_calls(void)    

{

  _printk0("<bfscall>");

  __fs_fastmutex_lock(&fssysmutex);

  fssysstate=1;

  if (fssyscounter>0) {

    _printk0("<bfscallfor%li>",fssyscounter);

    __fs_fastmutex_unlock(&fssysmutex);

    _printk0("<bfscallwait>");

#ifdef SHUTDOWNTIMEOUT

    {

      int counter;

      struct timespec delay;

      delay.tv_sec=SHUTDOWNSLICE/1000000;

      delay.tv_nsec=(SHUTDOWNSLICE%1000000)*1000;

      counter=0;

      while (counter<SHUTDOWNCOUNTER&&__fs_sem_trywait(&fssyssync)) {

        counter++;

        nanosleep(&delay, NULL);

      }

      if (counter>=SHUTDOWNCOUNTER) {

        printk(KERN_NOTICE "filesystem shutdown timeout... aborting!");

        sys_abort(371);

      }

    }

#else

    __fs_sem_wait(&fssyssync);

#endif

    _printk0("<bfscallresum>");

  } else {

    __fs_fastmutex_unlock(&fssysmutex);

  }

}

#endif