svn commit: r348737 - head/sys/kern

[Rodney W. Grimes]

[ Charset UTF-8 unsupported, converting... ]
> 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.

Oh, yes, I like this solution, then avaliable on demand at anytime
to anyone, but not present by default.

> John Baldwin
-- 
Rod Grimes                                                 rgrimes at freebsd.org