Re: Flushing buffer and page cache

From: Douglas Gilbert (
Date: Sat Feb 17 2001 - 13:24:38 EST

James Bottomley wrote:

> > Is it possible to flush all entries in the buffer cache corresponding
> > to a single block device (i.e. simply drop them if they aren't dirty,
> > or write them to disk and drop them after this if they are dirty)?
> Yes, just send the BLKFLSBUF ioctl to the device this syncs the device then
> removes all the buffers from the cache. We use it as a tool to move a SAN
> device around a cluster, which is similar to what you want to do.

Last time this question was raised, someone mentioned
a little utility called flushb . Here is its source:

 * flushb.c --- This routine flushes the disk buffers for a disk

 * modified August 2000 by Juri Haberland

#include <stdio.h>
#include <fcntl.h>
#include <linux/fs.h>

#define NOARGS void

const char *progname;

static void usage(NOARGS)
        fprintf(stderr, "Usage: %s disk\n", progname);

int main(int argc, char **argv)
        int fd;

        progname = argv[0];
        if (argc != 2)

        fd = open(argv[1], O_RDONLY, 0);
        if (fd < 0) {
         * Note: to reread the partition table, use the ioctl
         * BLKRRPART instead of BLKFSLBUF.
        if (ioctl(fd, BLKFLSBUF, 0) < 0) {
                perror("ioctl BLKFLSBUF");
        return 0;
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This archive was generated by hypermail 2b29 : Fri Feb 23 2001 - 21:00:15 EST