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-rw-r--r--e2fslib/flushb.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/e2fslib/flushb.c b/e2fslib/flushb.c
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+/*
+ * flushb.c --- Hides system-dependent information for both syncing a
+ * device to disk and to flush any buffers from disk cache.
+ *
+ * Copyright (C) 2000 Theodore Ts'o.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#include <stdio.h>
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if HAVE_SYS_IOCTL_H
+#include <sys/ioctl.h>
+#endif
+#if HAVE_SYS_MOUNT_H
+#include <sys/mount.h> /* This may define BLKFLSBUF */
+#endif
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
+
+/*
+ * For Linux, define BLKFLSBUF and FDFLUSH if necessary, since
+ * not all portable header file does so for us. This really should be
+ * fixed in the glibc header files. (Recent glibcs appear to define
+ * BLKFLSBUF in sys/mount.h, but FDFLUSH still doesn't seem to be
+ * defined anywhere portable.) Until then....
+ */
+#ifdef __linux__
+#ifndef BLKFLSBUF
+#define BLKFLSBUF _IO(0x12,97) /* flush buffer cache */
+#endif
+#ifndef FDFLUSH
+#define FDFLUSH _IO(2,0x4b) /* flush floppy disk */
+#endif
+#endif
+
+/*
+ * This function will sync a device/file, and optionally attempt to
+ * flush the buffer cache. The latter is basically only useful for
+ * system benchmarks and for torturing systems in burn-in tests. :)
+ */
+errcode_t ext2fs_sync_device(int fd, int flushb)
+{
+ /*
+ * We always sync the device in case we're running on old
+ * kernels for which we can lose data if we don't. (There
+ * still is a race condition for those kernels, but this
+ * reduces it greatly.)
+ */
+ if (fsync (fd) == -1)
+ return errno;
+
+ if (flushb) {
+
+#ifdef BLKFLSBUF
+ ioctl (fd, BLKFLSBUF, 0); /* In case this is a HD */
+#else
+ #warning BLKFLSBUF not defined
+#endif
+#ifdef FDFLUSH
+ ioctl (fd, FDFLUSH, 0); /* In case this is floppy */
+#else
+ #warning FDFLUSH not defined
+#endif
+ }
+ return 0;
+}