Date: Mon, 3 Jun 2019 18:43:54 -0600 From: Alan Somers <asomers@freebsd.org> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: Peter Eriksson <pen@lysator.liu.se>, "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: RFC: should an incremental reload of exports for mountd be optional? Message-ID: <CAOtMX2i-mZfLVuZx5KZ1LJiwMFB7%2BnduF=wtgFJy5x=JnOM0MQ@mail.gmail.com> In-Reply-To: <YQXPR01MB3128E549A195DF4B8DAD191BDD150@YQXPR01MB3128.CANPRD01.PROD.OUTLOOK.COM> References: <QB1PR01MB2643E5186098E2AF14934866DD190@QB1PR01MB2643.CANPRD01.PROD.OUTLOOK.COM> <D685FA4E-0F35-44F8-B341-CF59122E10B9@lysator.liu.se> <CAOtMX2hs-aQgEZaCQjNdMHuL8qxJTqnnvNQ%2BysRcpFFTEtDb1A@mail.gmail.com> <YQXPR01MB31289FF0AC8633D372C814A2DD140@YQXPR01MB3128.CANPRD01.PROD.OUTLOOK.COM> <CAOtMX2i23Gup6EZvVB9rL9HcCRarMroD=-O6W_OfDV_0Uz5n_Q@mail.gmail.com> <YQXPR01MB3128E549A195DF4B8DAD191BDD150@YQXPR01MB3128.CANPRD01.PROD.OUTLOOK.COM>
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On Mon, Jun 3, 2019 at 6:30 PM Rick Macklem <rmacklem@uoguelph.ca> wrote: > > Alan Somers wrote: > >Will a restart of the daemon cause clients to get HUPped if they try > >to access an exported filesystem while mountd is restarting? > >-Alan > I'm not sure what you mean by HUPped, but during a restart of mountd, extant > mounts should continue to work. Perhaps it wasn't SIGHUP, but I recall that a few years ago there was a problem where all NFS I/O would fail while mountd was reloading. I think it's the problem that you fixed in r241568. > > What will fail during the mountd restart is new NFSv3 mount attempts, because > they won't be able to talk to mountd via the Mount protocol. Usually the > failure will be rpcbind not having MOUNTPROG registered. > Then a retry of the mount (which will happen after something like 30sec if you > don't <ctrl>C the mount command) will succeed, assuming mountd has restarted. > Unmounts will complain the MOUNTPROG wasn't registered, but the umount > will work anyhow. > > Then "showmount", which is never guaranteed to return correct info, will report it > as still mounted. Since "showmount" never knows about NFSv4 mounts and just > returns its guess at what is mounted, I don't find it useful anyhow. > > NFSv4 mounts should continue to work when mountd isn't running, since they don't use the Mount protocol. And, since they don't use the Mount protocol, "showmount" > never knows about them. > > So, I restart can cause some disruption, but they are mostly just delays when doing > new NFSv3 mounts on the server. > > rick > > On Mon, Jun 3, 2019 at 5:13 PM Rick Macklem <rmacklem@uoguelph.ca> wrote: > > > > Thanks everyone for your comments. I just committed the patch with > > the incremental reload of exports always enabled. > > If people run into problems, I can add some "backdoor" way to disable > > it, as suggested by asomers@. > > > > A restart of the daemon will always do a full reload to work around any > > reload failures. > > > > rick > > > [stuff snipped]
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