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 */ 53 errcode_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
