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To: freebsd-hackers@freebsd.org
Subject: mount() flags
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Date: Wed, 22 May 1996 11:58:15 -0500
From: Randy Terbush <randy@zyzzyva.com>
Sender: owner-hackers@freebsd.org
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Could someone offer some feedback about the following scenario,
and perhaps some clues about the flags MNT_UPDATE and MNT_RELOAD?
These flags aren't mentioned in the manpage.

I have the following snippet of code. What I am trying to do is
change a read-only mounted filesystem to read-write, change something
on the filesystem, then remount read-only. This seems to cause
a system panic, (details currently unavailable).

Trying to duplicate the problem with a floppy device I am finding
that it looks as though these types of requests don't get queued.
It would also appear that I may be in for a challenge to figure
out how to wait for the first to finish.

Suggestions for the clueless are welcome.


In the case below, the second call to mount will fail
since the first call is still in progress. Is there a
way to wait() on the first call?

main ()
{
    struct ufs_args *ufs;
    
    ufs = (struct ufs_args *) malloc (sizeof (struct ufs_args));

    ufs->fspec = "/dev/fd0a";
        
    if ((mount (MOUNT_UFS, "/mnt", MNT_UPDATE, ufs)) != 0)
    {
	fprintf (stderr, "failed to change mount status\n");
	perror ("mount");
    }

    exec something here.....

    if ((mount (MOUNT_UFS, "/mnt", MNT_RDONLY, ufs)) != 0)
    {
	fprintf (stderr, "failed to change mount status\n");
	perror ("mount");
    }
}