kernel panic at quotactl with 5.2-current

Hello All

Steps for reproduce:

1) start with generic kernel.
2) install samba 2.2.8a from ports with quota & ACL support.
3) mount fat32 partition to some mount point, as example mount /mnt/dos
4) add to smb.conf 
[tmp]
   comment = Temporary file space
   path = /mnt/dos
   read only = no
   public = yes
5) mount this share via smbmount from linux box and start mc (i think it
work and with other access to this share)
...

This patch fixed this problem.

# cvs diff -u vfs_syscalls.c
Index: vfs_syscalls.c
===================================================================
RCS file: /mnt/storage/freebsd-cvs/src/sys/kern/vfs_syscalls.c,v
retrieving revision 1.343
diff -u -r1.343 vfs_syscalls.c
--- vfs_syscalls.c      6 Apr 2004 10:05:02 -0000       1.343
+++ vfs_syscalls.c      20 Apr 2004 15:50:20 -0000
_at__at_ -195,7 +195,7 _at__at_
        NDFREE(&nd, NDF_ONLY_PNBUF);
        error = vn_start_write(nd.ni_vp, &mp, V_WAIT | PCATCH);
        vrele(nd.ni_vp);
-       if (error)
+       if (error || !mp)
                return (error);
        error = VFS_QUOTACTL(mp, uap->cmd, uap->uid, uap->arg, td);
        vn_finished_write(mp);

-- 
Alex Lyashkov <shadow_at_psoft.net>
PSoft