rename(2) on open file loose unsync data

[manu@xxxxxxxxxx (Emmanuel Dreyfus)]

I have hit a bug in glusterfs on NetBSD, but I wonder if NetBSD FUSE is
the culprit, or if the problem is in glusterfs itself. If I rename and
open file, the unsync data get lost (it is replaced by a chunk of
zeroes).

The test case below exhibit the bug. Does it happens on Linux too, or is
it a problem in NetBSD FUSE?

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <err.h>
#include <sysexits.h>

int
main(void)
{
        int fd1, fd2;
        char buf[] = "abcdefgh";
        char buf2[] = "xxxxxxxx";

        (void)unlink("tmp");
        (void)unlink("tmp2");

        if ((fd1 = open("tmp", O_CREAT|O_RDWR, 0644)) == -1)
                err(EX_OSERR, "cannot open tmp");

        if (write(fd1, buf, sizeof(buf)) != sizeof(buf))
                err(EX_OSERR, "write failed");

        if (rename("tmp", "tmp2") == -1)
                err(EX_OSERR, "rename failed");

        /* No bug if fd1 is closed or fsync'ed before rename */
        (void)close(fd1);

        if ((fd2 = open("tmp2", O_RDONLY, 0)) == -1)
                err(EX_OSERR, "cannot open tmp2");

        if (read(fd2, buf2, sizeof(buf2)) != sizeof(buf2))
                err(EX_OSERR, "read failed");

        (void)close(fd2);

        printf("buf  = \"%s\"\nbuf2 = \"%s\"\n", buf, buf2);

        return 0;
}

-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu@xxxxxxxxxx