| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * flushb.c --- Hides system-dependent information for both syncing a
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| 4 | * device to disk and to flush any buffers from disk cache.
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| 5 | *
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| 6 | * Copyright (C) 2000 Theodore Ts'o.
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| 7 | *
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| 8 | * %Begin-Header%
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| 9 | * This file may be redistributed under the terms of the GNU Public
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| 10 | * License.
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| 11 | * %End-Header%
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| 12 | */
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| 13 |
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| 14 | #include <stdio.h>
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| 15 | #if HAVE_ERRNO_H
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| 16 | #include <errno.h>
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| 17 | #endif
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| 18 | #if HAVE_UNISTD_H
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| 19 | #include <unistd.h>
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| 20 | #endif
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| 21 | #if HAVE_SYS_IOCTL_H
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| 22 | #include <sys/ioctl.h>
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| 23 | #endif
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| 24 | #if HAVE_SYS_MOUNT_H
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| 25 | #include <sys/param.h>
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| 26 | #include <sys/mount.h> /* This may define BLKFLSBUF */
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| 27 | #endif
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| 28 |
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| 29 | #include "ext2_fs.h"
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| 30 | #include "ext2fs.h"
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| 31 |
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| 32 | /*
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| 33 | * For Linux, define BLKFLSBUF and FDFLUSH if necessary, since
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| 34 | * not all portable header file does so for us. This really should be
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| 35 | * fixed in the glibc header files. (Recent glibcs appear to define
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| 36 | * BLKFLSBUF in sys/mount.h, but FDFLUSH still doesn't seem to be
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| 37 | * defined anywhere portable.) Until then....
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| 38 | */
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| 39 | #ifdef __linux__
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| 40 | #ifndef BLKFLSBUF
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| 41 | #define BLKFLSBUF _IO(0x12,97) /* flush buffer cache */
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| 42 | #endif
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| 43 | #ifndef FDFLUSH
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| 44 | #define FDFLUSH _IO(2,0x4b) /* flush floppy disk */
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| 45 | #endif
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| 46 | #endif
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| 47 |
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| 48 | /*
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| 49 | * This function will sync a device/file, and optionally attempt to
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| 50 | * flush the buffer cache. The latter is basically only useful for
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| 51 | * system benchmarks and for torturing systems in burn-in tests. :)
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| 52 | */
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| 53 | errcode_t ext2fs_sync_device(int fd, int flushb)
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| 54 | {
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| 55 | /*
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| 56 | * We always sync the device in case we're running on old
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| 57 | * kernels for which we can lose data if we don't. (There
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| 58 | * still is a race condition for those kernels, but this
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| 59 | * reduces it greatly.)
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| 60 | */
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| 61 | if (fsync (fd) == -1)
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| 62 | return errno;
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| 63 |
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| 64 | if (flushb) {
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| 65 |
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| 66 | #ifdef BLKFLSBUF
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| 67 | if (ioctl (fd, BLKFLSBUF, 0) == 0)
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| 68 | return 0;
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| 69 | #else
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| 70 | #ifdef __GNUC__
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| 71 | # warning BLKFLSBUF not defined
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| 72 | #endif /* __GNUC__ */
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| 73 | #endif
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| 74 | #ifdef FDFLUSH
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| 75 | ioctl (fd, FDFLUSH, 0); /* In case this is a floppy */
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| 76 | #else
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| 77 | #ifdef __GNUC__
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| 78 | # warning FDFLUSH not defined
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| 79 | #endif /* __GNUC__ */
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| 80 | #endif
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| 81 | }
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| 82 | return 0;
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| 83 | }
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