1/* 2 * flushb.c --- Hides system-dependent information for both syncing a 3 * device to disk and to flush any buffers from disk cache. 4 * 5 * Copyright (C) 2000 Theodore Ts'o. 6 * 7 * %Begin-Header% 8 * This file may be redistributed under the terms of the GNU Library 9 * General Public License, version 2. 10 * %End-Header% 11 */ 12 13#include "config.h" 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 defined(HAVE_FSYNC) 62 if (fsync (fd) == -1) 63 return errno; 64#endif 65 66 if (flushb) { 67 68#ifdef BLKFLSBUF 69 if (ioctl (fd, BLKFLSBUF, 0) == 0) 70 return 0; 71#elif defined(__linux__) 72#warning BLKFLSBUF not defined 73#endif 74#ifdef FDFLUSH 75 return ioctl(fd, FDFLUSH, 0); /* In case this is a floppy */ 76#elif defined(__linux__) 77#warning FDFLUSH not defined 78#endif 79 } 80 return 0; 81} 82