void end_asynch_io(struct buffer_head *bh, int uptodate)
{
    register int i;
    ASYNCH_IO *io = (ASYNCH_IO *)bh->b_dev_id;

    mark_buffer_uptodate(bh, uptodate);
    unlock_buffer(bh);

    if (!io)
    {
       NWFSPrint("nwfs:  aio callback has NULL handle\n");
       return;
    }

    if (!test_bit(BH_Uptodate, &bh->b_state))
       io->ccode = ASIO_IO_ERROR;

    io->complete++;
    if (io->complete >= io->count)
    {
       for (i=0; i < io->count; i++)
          put_bh(io->bh[i]);

       if (io->call_back_routine)
          (io->call_back_routine)(io);
       io->signature = 0;

#if (PROFILE_AIO)
       profile_complete();
#endif
    }
    return;
}

ULONG aReadDiskSectors(ULONG disk, ULONG StartingLBA, BYTE *Sector,
		      ULONG sectors, ULONG readAhead, ASYNCH_IO *io)
{
    register ULONG i, j, bytesRead = 0;
    register ULONG bps;
    register NWDISK *NWDisk;

    if (sectors > 8)
       return 0;

    NWDisk = SystemDisk[disk];
    bps = NWDisk->BytesPerSector;

    for (i=0; i < sectors; i++)
    {
       io->bh[i] = get_bh();
       if (!io->bh[i])
       {
	  for (j=0; j < i; j++)
	     if (io->bh[j])
		put_bh(io->bh[j]);
	  return 0;
       }
    }

    io->ccode = 0;
    io->count = sectors;
    io->complete = 0;
    for (i=0; i < sectors; i++)
    {
       io->bh[i]->b_this_page = io->bh[(i + 1) % sectors]; // create circular list
       io->bh[i]->b_state = 0;
       io->bh[i]->b_next_free = (struct buffer_head *)NULL;
       io->bh[i]->b_size = 512;
       io->bh[i]->b_data = (char *)&Sector[i * bps];
       io->bh[i]->b_list = BUF_CLEAN;
       io->bh[i]->b_dev = (int)NWDisk->PhysicalDiskHandle;
       io->bh[i]->b_blocknr = (StartingLBA + i);
       io->bh[i]->b_count = 1;
       io->bh[i]->b_flushtime = 0;
       io->bh[i]->b_end_io = end_asynch_io;
       io->bh[i]->b_dev_id = io;
       clear_bit(BH_Uptodate, &io->bh[i]->b_state);
    }

    lock_kernel();
    ll_rw_block(READ, sectors, &io->bh[0]);
    unlock_kernel();

    run_task_queue(&tq_disk);

#if (DEBUG_AIO)
    NWFSPrint("io asynch read disk-%d lba-%d\n", (int)disk, (int)StartingLBA);
#endif

    bytesRead = (sectors * bps);
    return (bytesRead);

}

ULONG aWriteDiskSectors(ULONG disk, ULONG StartingLBA, BYTE *Sector,
		       ULONG sectors, ULONG readAhead, ASYNCH_IO *io)
{
    register ULONG i, j, bytesWritten = 0;
    register ULONG bps;
    register NWDISK *NWDisk;

    if (sectors > 8)
       return 0;

    NWDisk = SystemDisk[disk];
    bps = NWDisk->BytesPerSector;

    for (i=0; i < sectors; i++)
    {
       io->bh[i] = get_bh();
       if (!io->bh[i])
       {
	  for (j=0; j < i; j++)
	     if (io->bh[j])
		put_bh(io->bh[j]);
	  return 0;
       }
    }

    io->ccode = 0;
    io->count = sectors;
    io->complete = 0;
    for (i=0; i < sectors; i++)
    {
       io->bh[i]->b_this_page = io->bh[(i + 1) % sectors]; // create circular list
       io->bh[i]->b_state = 0;
       io->bh[i]->b_next_free = (struct buffer_head *) NULL;
       io->bh[i]->b_size = 512;
       io->bh[i]->b_data = (char *)&Sector[i * bps];
       io->bh[i]->b_list = BUF_CLEAN;
       io->bh[i]->b_dev = (int)NWDisk->PhysicalDiskHandle;
       io->bh[i]->b_blocknr = (StartingLBA + i);
       io->bh[i]->b_count = 1;
       io->bh[i]->b_flushtime = 0;
       io->bh[i]->b_end_io = end_asynch_io;
       io->bh[i]->b_dev_id = io;
       set_bit(BH_Uptodate, &io->bh[i]->b_state);
       set_bit(BH_Dirty, &io->bh[i]->b_state);
    }

    lock_kernel();
    ll_rw_block(WRITE, sectors, &io->bh[0]);
    unlock_kernel();

    run_task_queue(&tq_disk);

#if (DEBUG_AIO)
    NWFSPrint("io asynch write disk-%d lba-%d\n", (int)disk, (int)StartingLBA);
#endif

    bytesWritten = (sectors * bps);
    return (bytesWritten);

}

ULONG aZeroFillDiskSectors(ULONG disk, ULONG StartingLBA, ULONG sectors,
			  ULONG readAhead, ASYNCH_IO *io)
{
    register ULONG i, j, bytesWritten = 0;
    register ULONG bps;
    register NWDISK *NWDisk;

    if (sectors > 8)
       return 0;

    NWDisk = SystemDisk[disk];
    bps = NWDisk->BytesPerSector;

    for (i=0; i < sectors; i++)
    {
       io->bh[i] = get_bh();
       if (!io->bh[i])
       {
	  for (j=0; j < i; j++)
	     if (io->bh[j])
		put_bh(io->bh[j]);
	  return 0;
       }
    }

    io->ccode = 0;
    io->count = sectors;
    io->complete = 0;
    for (i=0; i < sectors; i++)
    {
       io->bh[i]->b_this_page = io->bh[(i + 1) % sectors]; // create circular list
       io->bh[i]->b_state = 0;
       io->bh[i]->b_next_free = (struct buffer_head *) NULL;
       io->bh[i]->b_size = 512;
       io->bh[i]->b_data = (char *) ZeroBuffer;
       io->bh[i]->b_list = BUF_CLEAN;
       io->bh[i]->b_dev = (int)NWDisk->PhysicalDiskHandle;
       io->bh[i]->b_blocknr = (StartingLBA + i);
       io->bh[i]->b_count = 1;
       io->bh[i]->b_flushtime = 0;
       io->bh[i]->b_end_io = end_asynch_io;
       io->bh[i]->b_dev_id = io;
       set_bit(BH_Uptodate, &io->bh[i]->b_state);
       set_bit(BH_Dirty, &io->bh[i]->b_state);
    }

    lock_kernel();
    ll_rw_block(WRITE, sectors, &io->bh[0]);
    unlock_kernel();

    run_task_queue(&tq_disk);

#if (DEBUG_AIO)
    NWFSPrint("io asynch fill disk-%d lba-%d\n", (int)disk, (int)StartingLBA);
#endif

    bytesWritten = (sectors * bps);
    return (bytesWritten);
}