Re: [NOT FIXED] Re: umount2

[Russell King]

Alexander Viro writes:
> Huh? What about more verbose output?

That's about as verbose as this mount gets, sorry.

> Urgh. What about doing the following trick: in fs/super.c::do_umount(),

Ok, added.  When I shutdown to single user mode and try to umount /var,
I get:

umount: busy (/log/wtmp)

If I thien "halt" from single user, I get:

umount: busy (/run/random-seed)
umount: busy (/log/wtmp)

It appears that touching a file creates these.  Eg, on a live system with
you patch in:

touch /var/run/tst
umount /var
 (brings up a list of busy dentries, not including /var/run/tst)
touch /var/run/tst
umount /var
 (brings up a list of busy dentries, *including* /var/run/tst)

The difference seens to be the way touch works.  In the second attempt,
strace reveals:

open("/var/run/tst", O_WRONLY|O_CREAT|O_EXCL, 0666) = -1 EEXIST (File exists)

Looking in fs/namei.c, open_namei(), it appears that the code is probably
following the path:

                dir = dget(nd->dentry);
...
                dentry = lookup_hash(&nd->last, dget(nd->dentry));
...
                if (dentry->d_inode) {
...
                        dput(dir);			/* dir is balanced again */
                        error = -EEXIST;
                        if (flag & O_EXCL)
                                goto exit;
...
exit:
        dput(nd->dentry);
        mntput(nd->mnt);
        return error;
	/* "dentry" is still in-use */
   _____
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  |   |         Russell King        [e-mail]      --- ---
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