LXR busybox/e2fsprogs/old_e2fsprogs/ext2fs/flushb.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * flushb.c --- Hides system-dependent information for both syncing a
   4 *      device to disk and to flush any buffers from disk cache.
   5 *
   6 * Copyright (C) 2000 Theodore Ts'o.
   7 *
   8 * %Begin-Header%
   9 * This file may be redistributed under the terms of the GNU Public
  10 * License.
  11 * %End-Header%
  12 */
  13
  14#include <stdio.h>
  15#if HAVE_ERRNO_H
  16#include <errno.h>
  17#endif
  18#if HAVE_UNISTD_H
  19#include <unistd.h>
  20#endif
  21#if HAVE_SYS_IOCTL_H
  22#include <sys/ioctl.h>
  23#endif
  24#if HAVE_SYS_MOUNT_H
  25#include <sys/param.h>
  26#include <sys/mount.h>  /* This may define BLKFLSBUF */
  27#endif
  28
  29#include "ext2_fs.h"
  30#include "ext2fs.h"
  31
  32/*
  33 * For Linux, define BLKFLSBUF and FDFLUSH if necessary, since
  34 * not all portable header file does so for us.  This really should be
  35 * fixed in the glibc header files.  (Recent glibcs appear to define
  36 * BLKFLSBUF in sys/mount.h, but FDFLUSH still doesn't seem to be
  37 * defined anywhere portable.)  Until then....
  38 */
  39#ifdef __linux__
  40#ifndef BLKFLSBUF
  41#define BLKFLSBUF  _IO(0x12,97)  /* flush buffer cache */
  42#endif
  43#ifndef FDFLUSH
  44#define FDFLUSH    _IO(2,0x4b)  /* flush floppy disk */
  45#endif
  46#endif
  47
  48/*
  49 * This function will sync a device/file, and optionally attempt to
  50 * flush the buffer cache.  The latter is basically only useful for
  51 * system benchmarks and for torturing systems in burn-in tests.  :)
  52 */
  53errcode_t ext2fs_sync_device(int fd, int flushb)
  54{
  55        /*
  56         * We always sync the device in case we're running on old
  57         * kernels for which we can lose data if we don't.  (There
  58         * still is a race condition for those kernels, but this
  59         * reduces it greatly.)
  60         */
  61        if (fsync (fd) == -1)
  62                return errno;
  63
  64        if (flushb) {
  65
  66#ifdef BLKFLSBUF
  67                if (ioctl (fd, BLKFLSBUF, 0) == 0)
  68                        return 0;
  69#else
  70#ifdef __GNUC__
  71# warning BLKFLSBUF not defined
  72#endif /* __GNUC__ */
  73#endif
  74#ifdef FDFLUSH
  75                ioctl (fd, FDFLUSH, 0);   /* In case this is a floppy */
  76#else
  77#ifdef __GNUC__
  78# warning FDFLUSH not defined
  79#endif /* __GNUC__ */
  80#endif
  81        }
  82        return 0;
  83}
  84