flushb.c revision 48e6e81362f264aee4f3945c14928efaf71a06c9
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 Public 9 * License. 10 * %End-Header% 11 */ 12 13#include <stdio.h> 14#if HAVE_ERRNO_H 15#include <errno.h> 16#endif 17#if HAVE_UNISTD_H 18#include <unistd.h> 19#endif 20#if HAVE_SYS_IOCTL_H 21#include <sys/ioctl.h> 22#endif 23#if HAVE_SYS_MOUNT_H 24#include <sys/mount.h> /* This may define BLKFLSBUF */ 25#endif 26 27#include "ext2_fs.h" 28#include "ext2fs.h" 29 30/* 31 * For Linux, define BLKFLSBUF and FDFLUSH if necessary, since 32 * not all portable header file does so for us. This really should be 33 * fixed in the glibc header files. (Recent glibcs appear to define 34 * BLKFLSBUF in sys/mount.h, but FDFLUSH still doesn't seem to be 35 * defined anywhere portable.) Until then.... 36 */ 37#ifdef __linux__ 38#ifndef BLKFLSBUF 39#define BLKFLSBUF _IO(0x12,97) /* flush buffer cache */ 40#endif 41#ifndef FDFLUSH 42#define FDFLUSH _IO(2,0x4b) /* flush floppy disk */ 43#endif 44#endif 45 46/* 47 * This function will sync a device/file, and optionally attempt to 48 * flush the buffer cache. The latter is basically only useful for 49 * system benchmarks and for torturing systems in burn-in tests. :) 50 */ 51errcode_t ext2fs_sync_device(int fd, int flushb) 52{ 53 /* 54 * We always sync the device in case we're running on old 55 * kernels for which we can lose data if we don't. (There 56 * still is a race condition for those kernels, but this 57 * reduces it greatly.) 58 */ 59 if (fsync (fd) == -1) 60 return errno; 61 62 if (flushb) { 63 64#ifdef BLKFLSBUF 65 if (ioctl (fd, BLKFLSBUF, 0) == 0) 66 return 0; 67#else 68#ifdef __GNUC__ 69 #warning BLKFLSBUF not defined 70#endif /* __GNUC__ */ 71#endif 72#ifdef FDFLUSH 73 ioctl (fd, FDFLUSH, 0); /* In case this is a floppy */ 74#else 75#ifdef __GNUC__ 76 #warning FDFLUSH not defined 77#endif /* __GNUC__ */ 78#endif 79 } 80 return 0; 81} 82