/*

 * flushb.c --- Hides system-dependent information for both syncing a

 * 	device to disk and to flush any buffers from disk cache.

 *

 * Copyright (C) 2000 Theodore Ts'o.

 *

 * %Begin-Header%

 * This file may be redistributed under the terms of the GNU Library

 * General Public License, version 2.

 * %End-Header%

 */

#include "config.h"

#include <stdio.h>

#if HAVE_ERRNO_H

#include <errno.h>

#endif

#if HAVE_UNISTD_H

#include <unistd.h>

#endif

#if HAVE_SYS_IOCTL_H

#include <sys/ioctl.h>

#endif

#if HAVE_SYS_MOUNT_H

#include <sys/param.h>

#include <sys/mount.h>		/* This may define BLKFLSBUF */

#endif

#include "ext2_fs.h"

#include "ext2fs.h"

/*

 * For Linux, define BLKFLSBUF and FDFLUSH if necessary, since

 * not all portable header file does so for us.  This really should be

 * fixed in the glibc header files.  (Recent glibcs appear to define

 * BLKFLSBUF in sys/mount.h, but FDFLUSH still doesn't seem to be

 * defined anywhere portable.)  Until then....

 */

#ifdef __linux__

#ifndef BLKFLSBUF

#define BLKFLSBUF	_IO(0x12,97)	/* flush buffer cache */

#endif

#ifndef FDFLUSH

#define FDFLUSH		_IO(2,0x4b)	/* flush floppy disk */

#endif

#endif

/*

 * This function will sync a device/file, and optionally attempt to

 * flush the buffer cache.  The latter is basically only useful for

 * system benchmarks and for torturing systems in burn-in tests.  :)

 */

errcode_t ext2fs_sync_device(int fd, int flushb)

{

	/*

	 * We always sync the device in case we're running on old

	 * kernels for which we can lose data if we don't.  (There

	 * still is a race condition for those kernels, but this

	 * reduces it greatly.)

	 */

#if defined(HAVE_FSYNC)

	if (fsync (fd) == -1)

		return errno;

#endif

	if (flushb) {

		errcode_t	retval = 0;

#ifdef BLKFLSBUF

		if (ioctl (fd, BLKFLSBUF, 0) == 0)

			return 0;

		retval = errno;

#elif defined(__linux__)

#warning BLKFLSBUF not defined

#endif

#ifdef FDFLUSH

		/* In case this is a floppy */

		if (ioctl(fd, FDFLUSH, 0) == 0)

			return 0;

		if (retval == 0)

			retval = errno;

#elif defined(__linux__)

#warning FDFLUSH not defined

#endif

		return retval;

	}

	return 0;

}