Date: Mon, 7 Nov 2016 22:12:13 +0000 From: Rick Macklem <rmacklem@uoguelph.ca> To: Colin Percival <cperciva@tarsnap.com>, "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: Mount protocol/showmount vs NFSv4 Message-ID: <YTXPR01MB018934F5E99E14021CB62F50DDA70@YTXPR01MB0189.CANPRD01.PROD.OUTLOOK.COM> In-Reply-To: <0100015840bc8135-cc77751d-68f4-48de-af77-b09327d24a0d-000000@email.amazonses.com> References: <YTXPR01MB01893AD86D5F1280DC63CA4BDDA40@YTXPR01MB0189.CANPRD01.PROD.OUTLOOK.COM>, <0100015840bc8135-cc77751d-68f4-48de-af77-b09327d24a0d-000000@email.amazonses.com>
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Colin Percival wrote: >Thanks for bringing this to the list, Rick. (This started with me asking >Rick why unmounting my nfsv4 mount was sending UDP packets.) > >On 11/06/16 12:51, Rick Macklem wrote: >> NFSv4 doesn't use the Mount protocol at all and does everything via the = NFSv4 protocol >> serviced at port #2049. > >It doesn't use the Mount protocol while the filesystem is in use, but our >umount(8) code does send UDP packets (which I understand are for the Mount >protocol) when unmounting an nfsv4 mount. Yes, I should have stated this. At least for NFSv4, it would seem that it s= hould not do any Unmount RPC. For NFSv3 over TCP, maybe it should use TCP instead of UDP= . >> I have never done anything about this, since most were still using NFSv3= , but it seems >> that maybe something should be done now? >> - What do people think of having a new option on mountd(8) that would be= used for >> NFSv4 only servers that disables servicing of Mount RPCs. > >Done in isolation, it seems that this would guarantee that unmounting an >nfsv4 filesystem will result in umount(8) hanging while it waits for >responses to the UDP packets it sends. So I'd think that we should fix >the client side to stop sending those first? Yes, the NFSv4 client should be fixed so that it doesn't do Unmount RPCs be= fore mountd gets changed. (I had thought of this, but neglected to mention it in= the first post. Thanks for bringing this up.) rick >-- >Colin Percival >Security Officer Emeritus, FreeBSD | The power to serve >Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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