blob: 45ed76512d4d99b541589c6061f4601ab296d762
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 | } |
84 |