release/src/router/busybox/e2fsprogs/old_e2fsprogs/ext2fs/flushb.c

   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  */
  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 (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 }