/* Remember where we've written the disk to speed up sync

   Copyright (C) 1994, 1995 Free Software Foundation, Inc.

   Written by Michael I. Bushnell.

   This file is part of the GNU Hurd.

   The GNU Hurd 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, or (at
   your option) any later version.

   The GNU Hurd 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., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include "ext2fs.h"

void pokel_init (struct pokel *pokel, struct pager *pager, void *image)
{
  pokel->lock = SPIN_LOCK_INITIALIZER;
  pokel->pokes = NULL;
  pokel->pager = pager;
  pokel->image = image;
}

/* Remember that data here on the disk has been modified. */
void
pokel_add (struct pokel *pokel, void *loc, vm_size_t length)
{
  struct poke *pl;
  vm_offset_t offset = trunc_page (loc - pokel->image);
  vm_offset_t end = round_page (loc + length - pokel->image);

  spin_lock (&pokel->lock);

  pl = pokel->pokes;
  while (pl != NULL)
    {
      vm_offset_t p_offs = pl->offset;
      vm_size_t p_end = p_offs + pl->length;

      if (p_offs == offset && p_end == end)
	break;
      else if (p_end >= offset && end >= p_offs)
	{
	  pl->offset = offset < p_offs ? offset : p_offs;
	  pl->length = (end > p_end ? end : p_end) - pl->offset;
	  break;
	}

      pl = pl->next;
    }
  
  if (pl == NULL)
    {
      pl = pokel->free_pokes;
      if (pl == NULL)
	pl = malloc (sizeof (struct poke));
      else
	pokel->free_pokes = pl->next;
      pl->offset = offset;
      pl->length = end - offset;
      pl->next = pokel->pokes;
      pokel->pokes = pl;
    }

  spin_unlock (&pokel->lock);
}

/* Sync all the modified pieces of disk */
void
pokel_sync (struct pokel *pokel, int wait)
{
  struct poke *pl, *next;
  
  spin_lock (&pokel->lock);

  for (pl = pokel->pokes; pl; pl = next)
    {
      pager_sync_some (pokel->pager, pl->offset, pl->length, wait);
      next = pl->next;
      pl->next = pokel->free_pokes;
      pokel->free_pokes = pl;
    }
  pokel->pokes = NULL;

  spin_unlock (&pokel->lock);
}