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