svn commit: r348737 - head/sys/kern

[John Baldwin]

On 6/6/19 10:39 AM, Alan Somers wrote:
> On Thu, Jun 6, 2019 at 11:35 AM Rodney W. Grimes
> <freebsd at gndrsh.dnsmgr.net> wrote:
>>
>>> Author: asomers
>>> Date: Thu Jun  6 15:04:50 2019
>>> New Revision: 348737
>>> URL: https://svnweb.freebsd.org/changeset/base/348737
>>>
>>> Log:
>>>   Add a testing facility to manually reclaim a vnode
>>>
>>>   Add the debug.try_reclaim_vnode sysctl. When a pathname is written to it, it
>>>   will be reclaimed, as long as it isn't already or doomed. The purpose is to
>>>   gain test coverage for vnode reclamation, which is otherwise hard to
>>>   achieve.
>>>
>>>   Add the debug.ftry_reclaim_vnode sysctl.  It does the same thing, except
>>>   that its argument is a file descriptor instead of a pathname.
>>
>> Should not this all be wrapped in some #ifdef or other protection,
>> is it really a good idea to have this on every single box running
>> FreeBSD?
> 
> I initially thought so too, but kib thought that it could be useful
> for debugging problems in the field.  The potential downside is
> limited, because only root can write to the sysctls, and the
> worse-case damage is similar to a "umount -f".

A compromise might be to stick this in a kernel module instead of in the
base kernel.  You could still kldload it in the field for debugging but
not necessarily have it directly available out of the box.

-- 
John Baldwin