kern/152079: [msdosfs] [patch] Small cleanups from the other NetBSD/OpenBSD

[Kostik Belousov]

On Sat, Mar 26, 2011 at 11:58:10AM +0200, Kostik Belousov wrote:
> On Sat, Mar 26, 2011 at 10:09:16AM +0200, Mikolaj Golub wrote:
> > 
> > On Fri, 25 Mar 2011 18:01:39 -0700 (PDT) Pedro F. Giffuni wrote:
> > 
> >  PFG> --- On Fri, 3/25/11, Kostik Belousov <kostikbel at gmail.com> wrote:
> > 
> >  PFG> ....
> >  >> No, I do not want it in our testing framework. I want to
> >  >> see a standalone test that demonstrates the issue.
> >  >> I think the leak is real, but want to have a way to
> >  >> reproduce it before committing.
> >  >> 
> >  >> The diff you pointed out to t_vnops.c does not make much
> >  >> sense to me.
> > 
> >  PFG> I looked a little more in their records and I found this:
> >  PFG> _____
> >  PFG> ...
> >  PFG>         /* rename directory over an empty directory */
> >  PFG>         md(pb1, mp, "parent");
> >  PFG>         md(pb2, mp, "parent/dir1");
> >  PFG>         md(pb3, mp, "parent/dir2");
> >  PFG>         RL(rump_sys_mkdir(pb1, 0777));
> >  PFG>         RL(rump_sys_mkdir(pb2, 0777));
> >  PFG>         RL(rump_sys_mkdir(pb3, 0777));
> >  PFG>         RL(rump_sys_rename(pb2, pb3));
> > 
> >  PFG>         RL(rump_sys_stat(pb1, &sb));
> >  PFG>         ATF_CHECK_EQ(sb.st_nlink, 3);
> >  PFG>         RL(rump_sys_rmdir(pb3));
> >  PFG>         if (FSTYPE_TMPFS(tc))
> >  PFG>                 atf_tc_expect_signal(-1, "PR kern/44288");
> >  PFG> ______
> > 
> >  PFG> There's also this that was removed once the PR was fixed:
> > 
> >  PFG> -        if (FSTYPE_MSDOS(tc))
> >  PFG> -                atf_tc_skip("test fails in some setups, reason unknown");
> > 
> >  PFG> hope that helps.
> > 
> > I suppose doing something like this on msdos fs:
> > 
> > mkdir parent
> > mkdir parent/1
> > mv parent/1 parent/2
> > ls -dl parent
> > 
> > In the case of the leak we should see 4 in hard links number field instead of
> > expected 3.
> No, the supposed leak only affects the vnode usecount, and not the
> inode hardlink count. The later is indeed reported as 1 for FreeBSD
> implementation of msdosfs, AFAIR.
> 
> Probably, the only way to verify the case is to use debugger.
Ok, after rereading the code, I do not believe that we need the
change. The doscheckpath() does vput() on tdvp, and tvp is vput'ed
right before line 1083, so jumping to the label `bad' instead of
`out' will only result in the lock assertion being fired.

Also, the msdosfs mount correctly unmounts after the attempt to
perform a rename that doscheckpath() banned. This is additional
evidence supporting my point.

The question is, why did you decided that the fix is needed for FreeBSD ?

> > 
> > But in FreeBSD it looks like msdosfs always reports link count 1:
> > 
> > /dev/md1 on /mnt (msdosfs, local)
> > 
> > [root at lolek ~]# cd /mnt/
> > [root at lolek /mnt]# mkdir parent
> > [root at lolek /mnt]# mkdir parent/1 parent/2 parent/3
> > [root at lolek /mnt]# ls -ld parent
> > drwxr-xr-x  1 root  wheel  4096 Mar 26 11:56 parent
> > 
> > Tested on 8-STABLE and CURRENT.
> > 
> > -- 
> > Mikolaj Golub


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