1 | /*
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2 | * flushb.c --- Hides system-dependent information for both syncing a
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3 | * device to disk and to flush any buffers from disk cache.
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4 | *
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5 | * Copyright (C) 2000 Theodore Ts'o.
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6 | *
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7 | * %Begin-Header%
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8 | * This file may be redistributed under the terms of the GNU Public
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9 | * License.
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10 | * %End-Header%
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11 | */
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12 |
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13 | #include <stdio.h>
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14 | #if HAVE_ERRNO_H
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15 | #include <errno.h>
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16 | #endif
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17 | #if HAVE_UNISTD_H
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18 | #include <unistd.h>
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19 | #endif
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20 | #if HAVE_SYS_IOCTL_H
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21 | #include <sys/ioctl.h>
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22 | #endif
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23 | #if HAVE_SYS_MOUNT_H
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24 | #include <sys/param.h>
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25 | #include <sys/mount.h> /* This may define BLKFLSBUF */
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26 | #endif
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27 |
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28 | #include "ext2_fs.h"
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29 | #include "ext2fs.h"
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30 |
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31 | /*
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32 | * For Linux, define BLKFLSBUF and FDFLUSH if necessary, since
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33 | * not all portable header file does so for us. This really should be
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34 | * fixed in the glibc header files. (Recent glibcs appear to define
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35 | * BLKFLSBUF in sys/mount.h, but FDFLUSH still doesn't seem to be
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36 | * defined anywhere portable.) Until then....
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37 | */
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38 | #ifdef __linux__
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39 | #ifndef BLKFLSBUF
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40 | #define BLKFLSBUF _IO(0x12,97) /* flush buffer cache */
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41 | #endif
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42 | #ifndef FDFLUSH
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43 | #define FDFLUSH _IO(2,0x4b) /* flush floppy disk */
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44 | #endif
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45 | #endif
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46 |
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47 | /*
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48 | * This function will sync a device/file, and optionally attempt to
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49 | * flush the buffer cache. The latter is basically only useful for
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50 | * system benchmarks and for torturing systems in burn-in tests. :)
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51 | */
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52 | errcode_t ext2fs_sync_device(int fd, int flushb)
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53 | {
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54 | /*
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55 | * We always sync the device in case we're running on old
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56 | * kernels for which we can lose data if we don't. (There
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57 | * still is a race condition for those kernels, but this
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58 | * reduces it greatly.)
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59 | */
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60 | if (fsync (fd) == -1)
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61 | return errno;
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62 |
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63 | if (flushb) {
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64 |
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65 | #ifdef BLKFLSBUF
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66 | if (ioctl (fd, BLKFLSBUF, 0) == 0)
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67 | return 0;
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68 | #else
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69 | #ifdef __GNUC__
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70 | # warning BLKFLSBUF not defined
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71 | #endif /* __GNUC__ */
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72 | #endif
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73 | #ifdef FDFLUSH
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74 | ioctl (fd, FDFLUSH, 0); /* In case this is a floppy */
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75 | #else
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76 | #ifdef __GNUC__
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77 | # warning FDFLUSH not defined
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78 | #endif /* __GNUC__ */
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79 | #endif
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80 | }
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81 | return 0;
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82 | }
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