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