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

[Kostik Belousov]

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.
> 
> 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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