Date: Thu, 6 Jun 2019 11:01:54 -0700 From: John Baldwin <jhb@FreeBSD.org> To: Alan Somers <asomers@freebsd.org>, "Rodney W. Grimes" <rgrimes@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r348737 - head/sys/kern Message-ID: <c6d9a869-d678-212b-0bc6-d0046f892e76@FreeBSD.org> In-Reply-To: <CAOtMX2iQ=Q9tR2MviXQDRqs_UNW6gQq=BGiDpNwXbpWjG%2BH7CQ@mail.gmail.com> References: <201906061504.x56F4odw034764@repo.freebsd.org> <201906061735.x56HZGIJ058845@gndrsh.dnsmgr.net> <CAOtMX2iQ=Q9tR2MviXQDRqs_UNW6gQq=BGiDpNwXbpWjG%2BH7CQ@mail.gmail.com>
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On 6/6/19 10:39 AM, Alan Somers wrote: > On Thu, Jun 6, 2019 at 11:35 AM Rodney W. Grimes > <freebsd@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
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